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One last possibly contentious point, any input on head cooling mod? Necessary/helpful? There are lots out there, though I would probably order from Cobra Engineering if I were going that route. Also brings up The coolant crossover delete idea. It would be really helpful with the bigger blower and larger intercooler water manifold neck. I could either use the ICT billet fittings and ‘make’ a new crossover, or I could use one of the kits that relocates the thermostat to the top side of the system.

Until next time

Phil
I saw the results of testing done by Accufab that led to the conclusion of the "head cooling mod" being a worthless modification for keeping certain cylinders in a Cobra MOD motor cool because the root cause of a particular cylinder running hot is not due to a coolant flow problem because a coolant flow problem in the Ford MOD motor DOHC cylinder does not exist.

I would suspect that companies offering a head cooling mod product do so with out any testing to prove their worth because why else would people be selling those things? Therefore, as I continue to collect parts for an upcoming 1000+ rear wheel HP 4.6 Teksid engine build, one product that I will defiantly not purchase is a "head cooling mod kit."
 

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The rationale behind all of the issues you have identified has previously been posted Phill so rather than repeating all of the logic I'll just give you the answers

Holy rear end information! I’ll reference that when I get farther along in that direction. I’m hoping that some of you guys can give me a referral to a local (NorCal) shop that can add 9” ends, straighten/brace/weld housing and tubes. I found TRZ 8.8 Fabrication and Tin Soliders Battle Ready 8.8 as two shops to prep an 8.8, but I think shipping would kill me cross-country especially these days.
Check out race car chassis shops within an acceptable driving distance of your home.


I looked around for a bit, found Winberg, Bryant, and Molnar make billet cranks for the 4.6
I imagine if this was a turbo car, Kellogg might be worry-free without stress on the snout like a blower has. I don’t want to buy something I don’t need, but I also don’t want to snap the snout off. I know some have done it, even with the stud mod, including Allen, with the newer Whipples. That concerns me....as I’m not sure what makes my build any different or less susceptible to the same. Something I considered: in order to keep parts cost at a reasonable level, I could use the DB heads I have on the shelf, get those freshened up with better springs, and use the remainder of the “ported heads fund“ and turn that into a billet crankshaft. Especially if I sold the two Kelloggs I have at the house also. Not committing to anything, just thinking aloud.....
Winberg and Bryant are the top two providers. Molnar is somewhere behind them. Molnar's cranks are very good. Winberg and Bryant are better. I used Winberg with a 1.400" diameter snout up from 1.250 and 0.700" longer.


Balancer etc: more and more reading, came across someone who apparently used to build 4+ lowers on the stock crank support. Double-band aid situation with the studded crank? Same logic applies here regarding aftermarket crank supports? That neither type of crank support guards against torsion stresses from rapidly decelerating the big blower rotors?

Crank supports in general are not helpful especially with a billet crank. Aftermarket supports are an absolute waste of money and you are correct about not protecting against torsional stresses which, are the real destroyers of crank snouts.


Thanks for the input on the stationary timing guides. Nice to pay ‘stock replacement prices’ on at least a couple things on this build. Speaking of stock pieces, I can’t remember if I asked, but cam shaft spacers. With the 12mm bolts holding the sprockets to the cams, any risk of shatter in a stock spacer? Opt for the stronger aftermarket pieces?
I have never seen or heard of it.


I ordered the ARP p/n 206-1001 with UHL of 2.085”, though I’ve also seen p/n 256-1001 recommended with 1.800” UHL. If this was an oversight I’ll send em back and replace with the shorter bolts.
That is the right bolt.


Any favorite/special oil pan recommendations for street/strip car? I called both Moroso and Canton, though Canton never got back to me. Steel was recommended in case of any accidental rock strikes on the screen, which makes sense. Not sure on capacity, baffles/trap doors. I have a PA Racing K member… called and left them a message to see if there was any known fitment or interference issues, but never heard back from them either.
Buy one that looks like the Canton/Moroso design.
175541


This was the basic design that Ford used on the 2000R Cobra engines. It works very wetl and only decreases ground clearance by an inch or so. If that is a problem you can modify the pan or ask to have it built shorter.


One last possibly contentious point, any input on head cooling mod? Necessary/helpful? There are lots out there, though I would probably order from Cobra Engineering if I were going that route. Also brings up The coolant crossover delete idea. It would be really helpful with the bigger blower and larger intercooler water manifold neck. I could either use the ICT billet fittings and ‘make’ a new crossover, or I could use one of the kits that relocates the thermostat to the top side of the system.
For a long time the mod was considered essential. With the mods Ford made to the coolant flow in later (DB & DC?) head castings and the newer head gasket coolant passage holes you don't hear as much about the problem — which was exhaust seats loosening and creating a ticking sound.

The best bet is to just have the exhaust seats replaced before using the heads. If you still want to run a coolant mod bypass, the nicest, highest quality one out there is the Cobra Engineering piece.

No matter what I highly recommend locating the T-Stat to the top of the engine like a conventional cooling system. The cooling model Ford uses was emissions inspired, not performance or efficacy inspired.


Ed
 

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I saw the results of testing done by Accufab that led to the conclusion of the "head cooling mod" being a worthless modification for keeping certain cylinders in a Cobra MOD motor cool because the root cause of a particular cylinder running hot is not due to a coolant flow problem because a coolant flow problem in the Ford MOD motor DOHC cylinder does not exist.
The supercharged engines experienced a problem that was characterized by a ticking sound on the driver's side of the engine. The head cooling mod was created to mitigate the problem. The problem was a relatively loose press fit of the exhaust seats in an OEM head casting. N/A the press fit produced little if any problems. Supercharged the light press fit in conjunction with coolant flow at the back of the diverside head caused exhaust seats to loosen. The head cooling mod was a bandaid. The correct fix was improved seats properly fit to the head and the use of the later head gaskets.



I would suspect that companies offering a head cooling mod product do so with out any testing to prove their worth because why else would people be selling those things? Therefore, as I continue to collect parts for an upcoming 1000+ rear wheel HP 4.6 Teksid engine build, one product that I will defiantly not purchase is a "head cooling mod kit."
The vast majority of the companies in the automotive aftermarket offer products that either duplicate an OEM product or offer some use, install or feature benefit not available in the OEM part. Even the larger aftermarket suppliers do not do the testing you are suggesting. If you like the part, buy it. If you don't then don't.

Th reason a manufacturer makes a part is to sell the part to make money offering what is not otherwise available to those who value the offering. Even OEM Tier 1 suppliers do not test their parts to "prove their worth".


Ed
 

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I saw the results of testing done by Accufab that led to the conclusion of the "head cooling mod" being a worthless modification for keeping certain cylinders in a Cobra MOD motor cool because the root cause of a particular cylinder running hot is not due to a coolant flow problem because a coolant flow problem in the Ford MOD motor DOHC cylinder does not exist.

I would suspect that companies offering a head cooling mod product do so with out any testing to prove their worth because why else would people be selling those things? Therefore, as I continue to collect parts for an upcoming 1000+ rear wheel HP 4.6 Teksid engine build, one product that I will defiantly not purchase is a "head cooling mod kit."
I've seen 4v passenger side heads that were severely discolored, showing a tremendous amount more heat than it's partner on the driver side. While I don't doubt John's testing and what he observed, his test is in a controlled environment and his main concern is racecar operation, not street car. Ford knew they had problems which is why there were several head revisions done to alleviate it. I don't see any reason why it's not something you should do for a real street driven car.
 

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I've seen 4v passenger side heads that were severely discolored, showing a tremendous amount more heat than it's partner on the driver side. While I don't doubt John's testing and what he observed, his test is in a controlled environment and his main concern is racecar operation, not street car. Ford knew they had problems which is why there were several head revisions done to alleviate it. I don't see any reason why it's not something you should do for a real street driven car.
I don't remember the exact details and conclusions of the coolant flow testing done by Accufab Racing that showed the lack of usefulness from a "head cooling mod product". However, the main points that I took away from the MOD motor cooling system testing done by John Mihovetz were that a cylinder overheating problem is the result of the a tuning, fueling issue and not a coolant flow issue.

Furthermore, remember that Robert Yates and Roush campaigned the Ford MOD motor in endurance road racing and the Roush/Yates MOD motor program did not see the need to install a "head cooling mod" in any of their engines.

Finally, in my case, my 2001 Cobra has run a Vortech super charger for over 10 years without a "head cooling mod" and I've never experienced engine cooling issues on the original 2001 short block, however, that could just be due to running a very mild tune up and operating the engine within reasonable limits.

So maybe all of these over heated MOD motor cylinders is the result of a way too aggressive tune up or stock parts operating beyond reasonable limits, but those are just assumptions on my part.
 

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Tony (badcobra) is correct, Jan. Ford issued several TSB's on the problem and spent considerable warranty dollars correcting the problem on customer cars. The passenger side head does not experience the problem because it feeds the heater circuit with the coolant tap on the back of the head. That continual flow of coolant from the back of the head and through the heater plumbing to the water pump (even when the heater is off) provides a different and better cooling for the back of the passenger side head than the dirver side gets.

Lets not forget that the head castings are the same except for cam drive and cam feed oiling which is controlled by using pipe plugs to open and close different oiling circuits depending on which side of the engine the head goes onto. That means the back of the driver side head has the same coolant flow as the front of the passenger side head. Significantly the front of the passenger side head never experiences the overheating problem the back of the driverside head does and the reason is, its coolant exits through the large hole on the intake manifold flange going directly to the radiator

The problem is simply coolant flow and the light press fit of the factory installed exhaust seats. When the head has a continuous flow of coolant there is no overheating and no problem. When it doesn't there is. The problem is not an aggressive tune from the factory. That doesn't exist. The factory tunes are simply optimized for emissions purposes not horsepower purposes. Moreover there is no evidence of the same tune producing the overheating problem anywhere else on the engine or after the use of the later redesigned coolant flow head gaskets.

The head cooling mod simply provides a heater style coolant path at the back of the driverside head to produce a passenger side heater plumbing like coolant flow at the back of the driver side head. If you use the most recent FelPro (and probably other brands also) MLS gaskets you will get the improved internal coolant flow for the driver side head. When you compare the coolant flow holes in the early and later gaskets to the later (SVT Cobra) gaskets, the later design gaskets have more and larger coolant transfer holes in the rear of the driver side gasket.

Irrespective of whether or not you choose to use one of the many bypass alternatives, if you use a PD blower, the exhaust seats definitely should be replaced with aftermarket seats using an improved press fit. The factory seats are OK for a n/a application and unsuitable for a supercharged application — especially a PD blown supercharged application.

PD blown applications experience immediate boost and therefore torque. This produces elevated combustion pressures and temperatures that, for all intents and purposes, are instantaneous. Centrifugal compressors of any type, crank driven or exhaust driven take time to get enough turbine speed to build similar boost levels. That means in a daily driver they are easier, at least on this part of the engine.

If you don't know which head gaskets you are using the easy fix is just use the cooling mod. I highly recommend Cobra Engineering's solution. The next time the heads come off the engine one of the first orders of business should be an exhaust seat replacement. BTW all the Roush-Yates competition mod motors used high dollar race seats and valves not the OEM counterparts and all engines had a race car cooling system not a daily driver cooling system. Attempting to compare the two is an apples and oranges sort of phenomena.


Ed
 

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BTW all the Roush-Yates competition mod motors used high dollar race seats and valves not the OEM counterparts and all engines had a race car cooling system not a daily driver cooling system. Attempting to compare the two is an apples and oranges sort of phenomena.


Ed

According to this article, the mod motor cooling system was stock:

Robert Yates' Electronically Fuel-Injected Four Valve V-8 Engine - Reality Racing
"Also surprisingly stock is the cooling system, including the water pump. An air pocket forms in the cylinder heads during the coolant fill, according to John, and his cure is to drill an orifice between the outside water jacket and the cylinder head, across the top side of the exhaust seats to discharge the air pocket behind the exhaust seat. "If you could stand the engine up when filling it, this would not be an issue," he says."

Of course a road race engine will have a higher capacity radiator than a production vehicle, but Yates saw no need to alter the cooling system on the MOD motor itself. Furthermore, when I was referring to an engine tune up, I was not talking about the factory tune up. I was suggesting that one of many possible cause of a hot running cylinder in a Cobra MOD motor is an overly aggressive tune up that has too much timing and leans out the air fuel ratio to dangerously high levels and the end result of such a tuning error is engine damage such as scuffed pistons, melted exhaust vales, etc.

I do agree that more robust exhaust valve seats are a good idea for a forced induction mod motor and I would take it a step further by considering using heavy duty exhaust vales as well. As a matter of fact, I recently contacted Manley Performance for advise on selecting vales for my supercharged Teksid build and based on my planned operating conditions, Manley suggested their "severe duty" intake valves and "extreme duty" exhaust vales for my application.
 

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According to this article, the mod motor cooling system was stock:

Robert Yates' Electronically Fuel-Injected Four Valve V-8 Engine - Reality Racing
"Also surprisingly stock is the cooling system, including the water pump. An air pocket forms in the cylinder heads during the coolant fill, according to John, and his cure is to drill an orifice between the outside water jacket and the cylinder head, across the top side of the exhaust seats to discharge the air pocket behind the exhaust seat. "If you could stand the engine up when filling it, this would not be an issue," he says."
The article and the engine RYR was speaking about was their first effort at the Daytona Prototype class with a 4.6L DOHC and the engine was using a lot of OEM componentry. The only thing stock about the cooling system however was the water pump style. The coolant flow went from the OEM emissions inspired version Cobra's came with, to a traditional water in the bottom, to the pump down the cylinder banks, up through the head gaskets into the head casting and out the top front of the heads to a thermostat and then the radiator. I have no doubt the exhaust seats were OEM on that first effort.

This is a pic of that first engine out of the article you quoted from;
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They did not win the Prototype event that year, finishing well back in the field. The picture below is the final incarnation of the Daytona Prototype engine that swept the Prototype class. It is a very different, purpose designed and built, take no prisoners, race engine

175555


RYR advertised the engine as a 520 HP engine to the media, pre-race. With only 20 additional horsepower over the previous years effort the consensus opinion was that the cars would finish well back in the field again. The actual RYR webpage for the engine also called out the power as 520 HP, see below;

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There was a wide spread belief, after the race, that RYR had sandbagged expectations by conservatively rating the engine power. The on track performance belied a much more powerful engine because of the way the RYR cars ran away from the more powerful competitors.

This engine did not use OEM seats or valves or porting. The heads were race ported, raised port FR500 style heads, a precursor to the GT500 head. The cooling system was the typical thermostat in the top hose to the radiator. RYR used a technique involving drilling an air bleed hole into the cavity under the exhaust ports that was prone to air locking. The air bleed hole improved cooling and longevity.


Of course a road race engine will have a higher capacity radiator than a production vehicle, but Yates saw no need to alter the cooling system on the MOD motor itself. Furthermore, when I was referring to an engine tune up, I was not talking about the factory tune up. I was suggesting that one of many possible cause of a hot running cylinder in a Cobra MOD motor is an overly aggressive tune up that has too much timing and leans out the air fuel ratio to dangerously high levels and the end result of such a tuning error is engine damage such as scuffed pistons, melted exhaust vales, etc.
RYR did alter the cooling system to a conventional style in both engines but they maintained the OEM water pump.

The many, many daily drivers that were never raced which also experienced the driver side "ticking sound failure" were all OEM tunes and were all serviced by Ford under their warranty program. While it is true that a poorly crafted aftermarket tune could produce a similar failure — it was not necessary to produce the failure. Hundreds if not thousands of non-performance vehicles with OEM tunes experienced the failures. Poorly crafted aftermarket tunes would only accelerate the failure. The failure was a Ford design issue addressed in ECO's for later head castings and head gaskets.


I do agree that more robust exhaust valve seats are a good idea for a forced induction mod motor and I would take it a step further by considering using heavy duty exhaust vales as well ...
We do agree on this.


Ed
 
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To clarify the party line, then, a HCM is still considered to be of value, especially on a DA or DB cast head?
So I was able to find a response from John Mihovetz at Accufab Racing concerning the value of a head cooling modification product:


“The 7-8 problem is mostly an airflow issue that favors those cylinders. Because of this those cylinders generate more heat. In order to reduce the heat you need to improve the coolant flow to the back of the block and also address the airflow distribution. The rear of both heads are fed with the same waterpump in the front. There is no force on either side of the rear of the head which causes the water to go either direction unless that hose is connected to a tee and the water goes somewhere else. A simple loop head to head at the rear doesn't do anything except waste money. This is very simple but hard for everyone to grasp. The water is going to take the path of least resistance. Other than the size of the holes in the head gasket there is nothing to direct the water in the block to the rear. Those holes can be changed to alter the flow to correct issues like this. Also to note is the use of an electric pump in the stock location typically makes this problem worse because those pumps to not generate pressure anywhere near what a stock pump does. This is research I did 20 years ago. I still have the block out in a container with 10 pressue sensors and 4 flow meters attached.Nothing has changed except HCM fantasy that came along. All done by con artists with no data to demonstrate it works. There is no data because it doesn't do anything. Go buy a flow meter. See for yourself.”
 

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So I was able to find a response from John Mihovetz at Accufab Racing concerning the value of a head cooling modification product:


“The 7-8 problem is mostly an airflow issue that favors those cylinders. Because of this those cylinders generate more heat. In order to reduce the heat you need to improve the coolant flow to the back of the block and also address the airflow distribution. The rear of both heads are fed with the same waterpump in the front. There is no force on either side of the rear of the head which causes the water to go either direction unless that hose is connected to a tee and the water goes somewhere else. A simple loop head to head at the rear doesn't do anything except waste money. This is very simple but hard for everyone to grasp. The water is going to take the path of least resistance. Other than the size of the holes in the head gasket there is nothing to direct the water in the block to the rear. Those holes can be changed to alter the flow to correct issues like this. Also to note is the use of an electric pump in the stock location typically makes this problem worse because those pumps to not generate pressure anywhere near what a stock pump does. This is research I did 20 years ago. I still have the block out in a container with 10 pressue sensors and 4 flow meters attached.Nothing has changed except HCM fantasy that came along. All done by con artists with no data to demonstrate it works. There is no data because it doesn't do anything. Go buy a flow meter. See for yourself.”


John has certainly made many significant contributions to the ModMotor space and so has RYR. The original overheating and exhaust seat failure phenomena was directly attributable to the Ford casting design of the 4 valve head in the area of the exhaust ports. Depending on the location of the cyclinder you were observing the problem was or sometimes was not significant, here's why.

The origin of the problem was a casting design that would allow a trapped air pocket under the exhaust ports and prevent coolant from entering. The problem was worst at the rear most pockets on the driverside head because of reduced coolant flow velocity. At higher coolant flow velocities, like the head saw closer to the front of the engine, the water pump produced enough turbulence that the air pocket was eventually filled with coolant.

The problem was most apparent at the back of the driver side head where coolant flow was lowest. On the passenger side head the heater coolant feed, off the back of the head provided the necessary flow velocity to properly purge the air bubble and cool the back of the head. The driver side of the engine had no similar feed to duplicate the events seen on the passenger side head.

Without a way to purge the air bubble from below the exhaust ports, the casting would eventually overheat enough to loosen the OEM exhaust seat(s) and the owner now had the 'head tick' problem requiring a new head. Ford warranty, brought Ford Engineering into the situation because the problem was costing warranty dollars that had not been forecast.

Through a series of incremental modifications to the head casting's coolant core around the exhaust ports, Ford Engineering eventually produced an improved cooling jacket design that fixed the overheating that produced the 'tick problem' and also the warranty cost escalation problem.

The final head design in the progression of ECO's was what we today refer to as the DC head. In addition to the DC head Ford also modified the number, location and size of the coolant passage holes in the head gaskets. The FelPro part numbers for the modified gaskets with these new and larger coolant passage holes are,
  • Driver side: : 26187 PT
  • Passenger side: 26222 PT
The driver side gasket looks like this from the bottom side. The two arrows point to the huge increase in coolant port area made to the gasket adjacent to cylinder #8. Note the tiny 'pin hole' provisions elsewhere.

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This is a top view of the corresponding gasket for the passenger side head.

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Notice the difference in water passage port areas.

Neither the DC head nor the modified gaskets for improved coolant flow were in existence at the time the Daytona Prototype engines were built and raced. Roush-Yates did things I am sure they did not publish but they also did things they would share.

One of those "things" was to drill an air bleed hole from the head's deck surface into the center of the trapped air pocket on the exhaust side of the head, effectively venting the trapped air pocket into the water jacket. This allowed the trappod air bubble to escape to the coolant cavity and get purged from the system.

This is what an GT500 style head modified with the air bleed looks like on the head's deck surface.

175559


If you ever saw one of those heads and wondered what those holes were about, now you know.

For anyone reading this thread, before you begin drilling willy-nilly on your high dollar heads get a junk head cut it open look at the air pocket under the exhaust ports, look at the exhaust ports, and remember you have to place that little air bleed hole through the air pocket without breaking through to an exhaust port!

Once you have correctly located the position and angle for your heads, go for it. If you can't, then don't! You don't need to ruin a pair of pricey and increasingly difficult to find heads.

A properly installed set of the Felpro gaskets, a HCM and a vacuum fill gizmo will do the same thing. BTW, while I don't know with certainty, I would not be surprised to discover RYR also modified the coolant transfer holes in the head gaskets that were available back in the day similar to what it sounds like John did also.

John's supposition that, "The 7-8 problem is mostly an airflow issue that favors those cylinders ..." may or may not be true. His heads used a proprietary race manifold that from outward appearances did not appear to favor any one port.

More significantly however, the right and left heads are identical castings. That means port 7 and port 8 on the driverside are the same as port 1 and port 2 on the passenger side.

Because the ports are in fact the same, then when placed on opposite banks of the engine those ports would still flow the same. That means the problem can not be a port flow problem because the exact same ports on the passenger side head do not overheat. The problem has to lie elsewhere.

The problem, as Ford Engineering discovered, and subsequently modified their casting design to correct, was related to an air pocket under all the exhaust ports on the 4V head that trapped an air bubble at coolant fill time. The back two cylinders on the driver side had such poor coolant flow that this became a an overheating and reliability problem.

So what to do?

If you are unable or unwilling to begin drilling holes in your high dollar heads then do the following;
  • Install the latest head gaskets,
  • Use DC castings whenever you can,
  • Install an HCM that does not dead head into the passenger side head. Both sides need to go to either the radiator or the water pump inlet,
  • Forget burping your cooling system,
  • Fill your cooling system using one of the cooling system vacuum fill kits.
The vacuum fill kit will eliminate the air bubble under the exhaust ports. Once all cooling system air is evacuated the water will fill all parts of the cooling system. These gizmos are cheap, usually coming in around $30 or $40 depending on whose you get and where you get it.

This stuff is not rocket science and it is not a black art. It is an unemotional and even handed observation of the problem, the causes and the formulation of a suitable fix — of which there can be more than one. Just keep the black magic unexplainable solutions out of your engine because more often than not they don't work and will cost you parts down the line.

Almost forgot to mention, John's comments about electric water pumps were spot on. The best one out there is the Davies Craig pump and it is a shadow of what the OEM mechanical pump is capable of producing flow-wise. If you run an electrical pump be sure you do everything possible to optimize the coolant flow at the back of the driverside head.


Ed
 

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This stuff is not rocket science and it is not a black art. It is an unemotional and even handed observation of the problem

Ed
I kinda like that. Takes away any bias. I have the newer gasket set you linked Ed, and I’ll get the HCM from James as discussed. I’ve found a vacuum fill kit, the Airlift 550000 550000 | Airlift™ Kit & Replacement Parts | CPS Products. Read some good reviews and watched a couple videos, figure I can use it for the intercooler system, on our other cars, and loan it to buddies so it’ll be a good investment. I’ll call it good for head cooling at that point.

Appreciate you guys adding some tech discussion to the thread. Makes it more useful for the next guy who comes along, especially while I stagnate in the parts-gathering phase.

I called Metco today, nice discussion with a guy named Rick there. Really knows his stuff. I’m going to go with their interchangeable crank pulley kit Interchangeable Crank Pulley Kit, : Metco Motorsports
They will swap the standard hub for the ATI-specific hub at no charge. Eliminating the stock caged lower will drop ~16lbs from the nose of the car as well, apparently, which is a nice bonus. Still undecided on upper/lower pulley size combo. Interestingly, they recommend a larger alternator pulley when upsizing the crank pulley, but offer one only for the stock alternator. I called Nations - they offer a 3.0” alternator pulley as an alternative to their standard 2.75” piece.

I decided I’m going to run the stock Kellogg crank. I’m going to have the snout tapped for the stud, have one full-length 3/16” key, a second 3/16” key placed but only as far back as to engage the damper, and no further. I’m using a dual-keyed Accufab wheel and will have the Cloyes crank sprocket milled. That should just about do it as far as the crank is concerned.



Phil
 

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I kinda like that. Takes away any bias. I have the newer gasket set you linked Ed, and I’ll get the HCM from James as discussed. I’ve found a vacuum fill kit, the Airlift 550000 550000 | Airlift™ Kit & Replacement Parts | CPS Products. Read some good reviews and watched a couple videos, figure I can use it for the intercooler system, on our other cars, and loan it to buddies so it’ll be a good investment. I’ll call it good for head cooling at that point.
That one is very nice! It fits into the Rolls Royce category from both a quality and a price perspective.


Appreciate you guys adding some tech discussion to the thread. Makes it more useful for the next guy who comes along, especially while I stagnate in the parts-gathering phase.

I called Metco today, nice discussion with a guy named Rick there. Really knows his stuff. I’m going to go with their interchangeable crank pulley kit Interchangeable Crank Pulley Kit, : Metco Motorsports
They will swap the standard hub for the ATI-specific hub at no charge. Eliminating the stock caged lower will drop ~16lbs from the nose of the car as well, apparently, which is a nice bonus. Still undecided on upper/lower pulley size combo. Interestingly, they recommend a larger alternator pulley when upsizing the crank pulley, but offer one only for the stock alternator. I called Nations - they offer a 3.0” alternator pulley as an alternative to their standard 2.75” piece.
Metco folks are a pleasure to do business with and their products are all top shelf. When you begin to noodle out the pulley combinations you want to use it will help to use the Fuel System Calculator, in the Terminator Table of Contents (TToC) sticky at the top of this forum, I think I pointed you at it earlier. Go down to Fuel Systems and you will find it as a downloadable XL spreadsheet for either PC or Mac's. Be sure to download the pdf instructions, although it is pretty straight forward.

Your blower overdrive ratio should be selected to put the blower rotor pack at approximately 19 no more than 20 thousand rpm or so at peak engine rpm. Once you find the ratio, you will probably use either an 8.1 or 8.6 inch diameter lower pulley. Metco calls the 8.1" pulley their 2 lb pulley and the 8.6 inch diameter their 4 lb pulley. Try to keep your top pulley between 3.25' and 3.5" for good belt wrap.

To keep belt slip to a minimum you want to run the largest diameter lower and upper you can, that will get you to your 19/20 thousand rpm rotor pack target rpm at peak engine rpm. Seems pretty simple and it is, except (seems like there is always an except hiding somewhere) the larger the lower the faster you will spin your alternator — which has a speed limit pretty similar to your blower rotor pack if it is a race alternator. The bigger alternator pulley that Rick was talking about is designed to prevent killing the alternator by overspending it — that's the good news.

The bad news is that as you increase alternator pulley diameter to protect it, you slow it down at normal driving speed which is no big deal until you slow it down below its turn on point. Once it falls below the rpm the field windings activate at, it stops charging or charges intermittently if it is wandering slightly above and then below turn on rpm. The fix is either a slightly smaller pulley on the alternator and don't shift at peak engine rpm or go to an aftermarket unit that can safely run up to 20/22 thousand rpm so you can spin it a faster to get idle charging and still not grenade it at peak shift rpm.

My recommendation is stick with the stock unit initially. Take it down to your local alternator rebuilder and ask him to test it on his machine to see what rpm it turns on at and what it puts out. That will tell you what size alternator pulley you need, to have it charge normally as you are daily driving the car. If and/or when the rpm finally does it in, then you can search for a high-performance aftermarket unit with a high peak operating rpm limit.


I decided I’m going to run the stock Kellogg crank. I’m going to have the snout tapped for the stud, have one full-length 3/16” key, a second 3/16” key placed but only as far back as to engage the damper, and no further. I’m using a dual-keyed Accufab wheel and will have the Cloyes crank sprocket milled. That should just about do it as far as the crank is concerned.

Phil
Good decisions and good crank. You will be quite happy with it.


Ed
 

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By using the stud and a non aggressive clutch you can substantially extend the life of a stock crank snout even better than the original OEM support.

Ed
Hi there, when you say aggressive Clutch are you referring to a twin disc? I'm currently on a single disc with an old 3.4 Whipple at about 28 to 29 pounds and was thinking of going with a RXT 1,000 HP twin disc. I have a caged 4 pound lower and shift at about 6,500 RPMs so my blower is at about 17,500 max on RPMs. This whole thread is interesting but this perked my ears and I was just curious, thanks Ed.

-Justin
 

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Hi there, when you say aggressive Clutch are you referring to a twin disc? I'm currently on a single disc with an old 3.4 Whipple at about 28 to 29 pounds and was thinking of going with a RXT 1,000 HP twin disc. I have a caged 4 pound lower and shift at about 6,500 RPMs so my blower is at about 17,500 max on RPMs. This whole thread is interesting but this perked my ears and I was just curious, thanks Ed.

-Justin
When I use the aggressive clutch moniker to describe a clutch it specifically refers to how grabby or slippery the clutch engagement is, Justin. That is normally a function of the disc material and the pressure plate load and to a lesser extent the number of discs.. The coefficient of friction for the disc material is a direct indication of how aggressive the clutch is.

To use a brake pad example, organic brake pads provide a very smooth grip on the disc and slow the car with minimal brake pedal pressure. A sintered iron (metallic pad) when cold requires considerable pedal effort to produce the same stopping experience. Once the pads and discs heat up the metallic pads require a normal sometimes even light pedal pressure to stop the car.

The hot metallic pad has a higher coefficient of friction than the cold metallic pad and certainly the organic pad. Same thing in clutches. The organic discs will provide the smoothest engagements but can not handle high torque loads like a blown motor can produce. As the disc material progresses from Kevlar to ceramics to sintered iron the aggressiveness of the clutch engagement increases also.

A Cobra T-56 has a 2.66:1 first gear and a 1.78:1 second gear. That means on a gear change you will experience a 33% reduction in engine speed. For easy math I am going to use a rotor pack rpm of 18,000 rpm at the shift. That means your rotor pack will go from 18,000 rpm to 12,000 rpm in a microsecond as the clutch locks up.

A rotor pack at 18,000 rpm has stored kinetic energy just like a flywheel. When you instantly reduce that rotor pack rpm to 12,000 all that stored energy trys to twist the crank snout off the front of the crankshaft. The damage is a torsional event not a bending event.

If you have a clutch that slides a bit on the gear change the impact on the crank snout is measurably reduced. That's the good news. The bad news is the clutch, which is already a consumable, becomes even more consumable. Another aggravating issue is the actual rotor pack rpm when you finally release the clutch in the next gear. Because we can not manually shift like an automatic the real rotor pack rpm is more like 20,000 rpm or higher when the clutch re-engages, which means even more damage to the crank snout,


Ed
 

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Something to keep in mind about progressive transmissions is that the gear changes always have to follow the preprogrammed / designed sequence 1-2-3-4-5-6 that the transmission was designed with. They do not make provisions for skipping a gear for example in the downshift sequence because the vehicle speed is too low for the next lower gear ( a road race environment) or the traffic situation requires the use of first gear because of the presence of a stop sign or light.

The traffic scenario is an everyday phenomena and the road race style scenario is also an everyday experience, admittedly at a lower performance level than the road race variant but every bit as real. A stop light or sign would cause you to need to downshift through all lower gears to get to first gear to accelerate from a stop. Similarily traffic conditions have an ebb and flow to them that can require a downshift of two or more gears.

The sequential shifting mechanism transmissions bring with them a sequential gear selection mandate that can quickly become unattractive in a daily driver. I suspect the buyer remorse factor for purchases made for daily driving is going to be high. For drag racing likely no remorse factor, for everything else varying degrees of remorse depending on gear change characteristics and frequency for the particular usage and how quickly the sequential gear change capability ages in the owner's hierarchy of important characteristics for the transmission.

Another consideration is the PPG replacement gears that are installed in the T-56 case. The transmission has multiple gear sets available from 700 ft lbs torque capacity up to over 1000 ft lbs in some representations and 1000 HP in other representations in four or five different ratio combinations.

If there are only four different torque capacity gear sets in only four different ratios that means there are sixteen different internals combinations possible. I tend to doubt that.

Additionally, the torque ratings are suspect. If you compare the photographic images of the gears to the T56 Magnum gears rated at 700 ft/lbs of torque or the specialized Transzilla gears that are rated substantially higher, The PPG gears look like first generation T56 gears.

Photographic appearances not withstanding, you really need to view the PPG gear set next to a Magnum or Transzilla gear set in the same photo. The PPG gears none the less do not appear as robust as the Magnum or Tranzilla gears — strength claims to the contrary not withstanding.


Ed
I do not doubt the torque ratings that PPG rates their gear sets at when you compare a PPG T56 gear seat to a stock Tremec gear set.

Stock Tremec gear on the left and a replacement PPG T56 gear on the right. Notice that the gear teeth on the PPG part are larger to handler bigger torque loads.
 

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Interesting pics, Jan. The input shaft on the right that I believe you identify as the PPG unit appears smaller than the shaft on the left. Additionally the bearing appears smaller also. Although the teeth are visibly larger the strength is not as easily determined. Material and heat treat will play significant roles in the strength of the finished part.

PPG may well have tested all the various gear sets on a transmission dyno to determine their various torque capacities. only PPG can tell us how they came up with their torque ratings.. The transmission dyno approach, while accurate, is not insignificant either in time or required effort. The best way to find out, if someone really wants to know, is simply to ask PPG. I am sure they would volunteer the information.

Whenever I see transmissions rated by horsepower it always makes me cautious. Transmissionis are rated by torque for a reason. A 1000 horsepower engine that gets its power at 11,500 rpm, like the old Prostock engines before the rules changes, only needs 460 ft/lbs of TQ to get that horsepower number. On the other hand the engine that gets its1000 hp at 6500 RPM needs 800 ft/lbs of TQ to do the job. Both produce 1000 hp but the engine that makes that power at 6500 rpm needs a dramatically stronger transmission.

Don't misunderstand, the sequential shifting technology they developed and employ is very impressive. For some applications it is just what the doctor ordered. For others, probably not so much. There also appears to be special requirement, identified in some of their literature, for the engine to be flat shifted, which sounds like what we call power shifting.

Their literature says, "Flat shift is a term used to describe a gear shift where the throttle remains at 100% and the gear change is completed. This is achieved using ECU calibration that allows very accurate ignition and fuel cuts to allow the gearbox to reduce the torque and load on the gearbox. Once the ignition cuts take effect the gear can be moved into the next higher gear. Flat shift can be very complex in modern ECU systems with lots of data and sensors contributing to this import(ant) phase of a sequential gearbox".

Their commentary about requiring the ECU to participate, and the fact they think flat shifting can be very complex in modern ECU systems with lots of sensors etc. leads me to believe there is considerably more to implementing one of these transmissions in a car than, at first, meets the eye.

In other places they suggest that down shifts require equalizing the speed differences between gears on a down shift by correctly blipping the throttle, They go on further to say that, "Failure to have correct matching gear speeds, lead(s) to wheel lock up ..." This sounds like an unsynchronized, racing transmission with the ability to engage two gears at the same time!

Just a lot of, as yet, unknowns and operational quirks that need to be clarified, torque capacity and sequential shifting not withstanding. ...


Ed
 

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I have a similar build to what you are planning, but with unported heads. I would definitely go ahead and get the heads and intake ported while you have it apart, it's expensive, but will be worthwhile if you want reliability (less boost). I really do regret not doing it.

My car put down 964rwhp on pump E85 through a TH400 and 9" rear, 30#'s of boost and didn't play with timing much, kept it really low at 15* (I look forward to having tuning room at the track with this). Your goal is more than reasonable, but reliability is never "simple" at 1000rwhp on these cars. You will have drivetrain issues, belt issues, and random parts failures.

FWIW, I run the MS3 p&P and am more than happy with it. It does everything I need it to do, is insanely simple, and retains the stock gauges.
 

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I have a similar build to what you are planning, but with unported heads. I would definitely go ahead and get the heads and intake ported while you have it apart, it's expensive, but will be worthwhile if you want reliability (less boost). I really do regret not doing it.
Another option for head porting if you are worried about costs is to do it yourself. If you can build your own mod motor and degree cams yourself then I don't think it will be difficult to port heads yourself, just time consuming more than anything. Now somebody might cook up a giant word salad of a response to discourage you from porting heads yourself, but I think its a viable option and racers and professional engine builders such as Accufab Racing have been successfully porting heads by hand for decades with excellent results.

Do It Yourself Head Porting
 

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If you have never ported heads before you are in for a surprising experience. The physical effort required is not for the weak or timid. The biggest improvements will come from a clean up of the bowl area right behind the valve. Many newcomers to head porting will be seduced by ultimate flow numbers. More seasoned porting impresarios will recognize the important numbers are the low and mid lift flow numbers.

During a complete cylinder fill the valves will only be at maximum lift (and therefore flow) one time. However they will visit every other valve lift point two times per cylinder fill or exhaust event. Most importantly the lowest lift figures represent the largest contributors or alternatively discounts to volumetric efficiency.

If your port flow is lazy at low lift your engine will behave similarly. Poor low/mid lift flow numbers will make the engine want a later inake valve closing point in an effort to recapture the volumetric efficiency and performance that was lost to the uninformed head porting effort. As you've probably already guessed, that does not work.

Even long standing well respected porting shops will show significant differences shop to shop in terms of low lift air flow. If the head porting process was easy to do they should all come up with the same sterling low lift flow numbers and they don't. Take a moment to look at the table below;
175618

All the heads come in at about 330 cam at .500 lift. Up through .400 lift one head, Livernois, outperforms everybody, including ported Coyote heads!

This kind of performance is not achieved by duplicating YouTube porting video clips. Remember when you hurt the low lift flow you profoundly injure all but wide open throttle high rpm performance. You can turn an OK performer into an unhappy and unpleasant to drive engine / car.

If you still want to take a shot at doing your heads yourself, spend $25 and buy Dave Vizard's book on How to Port & Flow Test Cylinder Heads. Dave does an excellent job of teaching what is important. This ought to be a must have book in your performance library. The $25 price tag is much less than the cost of the welding repairs necessary to fix that well intentioned but il informed and incorrectly executed head porting event in your garage or basement.


Ed
 
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