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N/A Build now Forced Induction

2K views 3 replies 2 participants last post by  eschaider 
#1 ·
As the title suggests I'm going F/I as opposed to the N/A build originally discussed in another forum thread.
So, I purchased a Termi setup with an H122 GT500 take off from another forume site.
https://www.modularfords.com/threads/250434-4-6-4V-to-5-4-4V-H122-kit
My goal is not a max effort race car, but a streetable, fun car. My car is a Factory Five cobra replica. Wet weight is right aound 2200 lbs. The essentiaally stock 98 cobra motor was fun, but lacked low end punch.

What I have already

-98 Teksid block
-Boss Rods
-Speed pro forged pistons. (stock dish)
-C heads, mild port job (gasket match) with 98 Cobra intake cams, cooling mod.
-Red Monster COP Conversion

-High Volume oil pump, Billet gears.
-Composite windage tray
-ARP head studs

The plan..

Here is the plan thus far..

Stock Term intake, intercooler,Cobra Engineering H122 adapter plate, H122 GT 500 take off
Stock Termi fuel rails, 39 lb injectors.
Kenne Bell BAP
Custom intercooler tank, rear mounted, heat exchangers (from snowmobile) to and from tank, with a suitable rad in front of car.
Custom intake using accufab or bbk throttle body(anyone have one?) And adapter plate to blower snout.
Stock mass airflow.. Suggestions here?
My initial thoughts are to route the intake down in front of the engine to cool air, but that will be decided later.

I want to use the 98 front cover as everthing is pretty much custom anyway. I will need some 8 rib pulleys, and specifically an 8 rib harmonic balancer.

SCT tuner with custom tune

Questions for now?

What is a good balancer option?
How do I deal with the return vs non return(termi) system.
Cuurently have 5/16" fuel supply line. Will that be enough?

A quick note about myself... I am a machinist/millwright/welder and love a challenge. Especially when it involves internal combustion!

That is all I can think of for now. There will be MANY more questions as this project progresses.
Thanks to all for your help and ideas.

Cheers

Tom
 
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#2 · (Edited)
...I'm going F/I as opposed to the N/A build originally discussed in another forum thread.
... The essentiaally stock 98 cobra motor was fun, but lacked low end punch.
The use of a Centri will give you more torque than the n/a engine did but not until the centri comes up to sufficient impeller speed to build boost. Until it does the engine is basically n/a. That said the incremental boost that the engine sees as the engine speed comes up will be slightly better than the n/a equivalent but a very far cry from the boost and low speed torque a positive displacement (PD) blower will provide. With a manual transmission you will want to be using a PD blower to produce the seat of the pants effect you are looking for.

What I have already

-98 Teksid block
-Boss Rods
-Speed pro forged pistons. (stock dish)
-C heads, mild port job (gasket match) with 98 Cobra intake cams, cooling mod.
-Red Monster COP Conversion

-High Volume oil pump, Billet gears.
-Composite windage tray
-ARP head studs.
I am not certain what you mean by Boss Rods. The connecting rod you should be using is one of the H-Beam Manleys or equivalent. The speed pro pistons you are planning to use will cost you more than you would spend if you went to a set of custom billet Gibtecs. Gibtec has built a special piston package for the Modmotor that comes with tool steel pins (you need them on the blown version of the engine), TotalSeal piston rings, locks of your choice and c/r of your choice for $1,200 total. Check out this Article => Gibtec Pistons. There is another excellent build thread in the Terminator Table of Contents (TToC) that you ought to review before spending money on parts. It is Joe Goffin's Aluminator Gibtec Build (<= clickable) thread

Joe's thread will give you chapter and verse, with excellent pics, on the correct way to approach and execute your build. Not to pick on your parts choice but most people think of the Cobra pump as the high volume oil pump. It is higher than the 2V pump but the pump you want is the GT500 or 3V pump with the Boundry Billet gears. Joe covers that in his build.

ARP makes two different head stud packages for our engines, one is 8740 and the other is 2000 steel. You do not want the 8740 studs you do want the 2000 studs. There is a complete listing of the ARP fasteners needed for a Modmotor build in the TToC under the Engine builds thread. It is the first entry in that section. Download the pdf it will save you from buying the wrong stuff.

The plan..

Here is the plan thus far..

Stock Term intake, intercooler,Cobra Engineering H122 adapter plate, H122 GT 500 take off
Stock Termi fuel rails, 39 lb injectors.
Kenne Bell BAP
Custom intercooler tank, rear mounted, heat exchangers (from snowmobile) to and from tank, with a suitable rad in front of car.
Custom intake using accufab or bbk throttle body(anyone have one?) And adapter plate to blower snout.
Stock mass airflow.. Suggestions here?
My initial thoughts are to route the intake down in front of the engine to cool air, but that will be decided later.
The Cobra Engineering adapter plate will allow you to use the GT500 M122 Eaton blower. This is an excellent low cost alternative that can easily get to well over the 600 WHP threshold with about the same torque for essentially idle all the way up the engine operating range and still maintain a stock idle with good driving manners. Your injector choice is way too small you should be looking at 60# injectors. KB BAPs have always worked well. For a street driven vehicle I would opt for a Killer Chiller and save the expense and plumbing of all the rear mounted intercooler tank hardware (more on that in a later post).

If you can find one of the Dragon SBTBs they were the largest of the original 03/04 Cobra SBTB that could be fit onto the first generation intake plenum flanges. Some of the nicest SBTB today are available from Justin at VMP but the big ones will require an adapter to fit to the 03/04 plenum flanges. The exception to this is the aftermarket GT500 SBTB's that will fit the GT500 M122 blowers.

I am not sure what you mean by adapter plate to blower snout. I strongly encourage you to use one of the Pro-M 92 MAFs (<= clickable) they are simply the best MAF that you can buy at any price.

I want to use the 98 front cover as everthing is pretty much custom anyway. I will need some 8 rib pulleys, and specifically an 8 rib harmonic balancer.
If you go the PD blower route the 03/04 Cobra cover will make life easier. The second best cover to use is the 4.6 Navi cover although it will require some fabrication work to fit the front blower drive pieces on. The 98 cover will work also but again some additional fabrication work is required.

SCT tuner with custom tune
I highly recommend you use the Binary Editor Software from Core Tuning if you stay with the OEM ECU. A better choice is to go to the aftermarket on the ECU and get away from the limits of the OEM electronics. Check out MSPro-Ultimate Standalone (<= clickable)

Questions for now?

What is a good balancer option?
How do I deal with the return vs non return(termi) system.
Cuurently have 5/16" fuel supply line. Will that be enough?
BHJ makes an excellent 8 rib balancer for the Modmotor click here => BHJ balancer that will accept Metco interchangeable pulleys. BHJ lists it as a 5.4 damper but it fits perfectly on a 4.6 and gives you the 8 rib support you were looking for.

I have a personal preference for returnless style fuel systems for the street and return style for the track. Both work in either application but require a tuner and fuel system designer that knows what he is doing. Most guys default to the return style because it is easier for them to understand and implement. The returnless style is easily better for the street and the return style is easily better for the track. The fuel system decision is down the road and will take a great deal more discussion.

A quick note about myself... I am a machinist/millwright/welder and love a challenge. Especially when it involves internal combustion!

That is all I can think of for now. There will be MANY more questions as this project progresses.
Thanks to all for your help and ideas.

Cheers

Tom
Your fabrication skills will play to significant advantage for you Tom. What you are building is going to make use of them extensively. The fit in the '65 engine compartment is tight but absolutely doable just take your time. The replica manufacturers sometimes position the Modmotor, particularly in these cars for easy exhaust header routing. When you place your engine in, position it so the TKO 600 (I am assuming that is what you're using) tailshaft mount sits directly on the chassis crossmember for the mount. When you install the engine like that you may have to redo your header adapter pipes form the engine to your side pipes.

If you have not already purchased side pipes you might want to consider the under chassis exhaust routing. The reason for the under-chassis routing is the exit on the side pipes is 24 inches below your left ear. If you already have the side pipes you know what I am talking about. You can reduce the level of exhaust noise your ear is subjected to by slightly canting the side pipe exits towards the ground. The challenge with this fix is the dust that the sidepipes will kick up on a dusty surface when the car is idling and not moving. Sort of a six of one half a dozen of the other sort of problem.

Ed
 
#3 ·
Hi Ed. Thanks so much for all the great info. All good stuff. I will be checking out the gibtec aluminator thread for inspiration for sure.
The boss rods I mentioned are actually Coyote boss rods. Much beefier than the 4.6 rods. Got then from Tasca. They are a cracked powdered piece, but look to be shot peened as well (don't quote me on that though). All the parts listed are part of the current shortblock. Unfortunately, family life, kid going to university, etc, dictates I be as frugal as possible with my build. That being said, I want it to all work properly when done. Ideally, 450 whp is all I need for my car. Any more and things can get scary very quickly. 2200lbs with a 92" wheelbase and 5:1 lbs/hp commands a lot of respect.
I have already driven my car for a season with the stock 98 with C heads. An absolute blast to drive, but it need the extra torque and a little more hp to really bring it alive. And yes, thos sidepipes are LOUD AS HELL! I did turn the tips down and put some bafffles, but it still requires earplugs. Before the baffles it was actually painful.
Again, i truly appreciate your help. Looking forward to posting my progress. So you know, things happen slowly... Family comes first. I've been told😁
Cheers
Tom
 
#4 · (Edited)
Tom,

Those powdered metal rods are unusable in a supercharged 03/04 style Modmotor. You should sell them while they are still new. Your 450WHP is easily achieved with the original 03/04 Cobra Eaton.

As loud as your n/a engine was, it will will be mild compared to the exhaust note of the blown version of the engine. FWIW, if I am not mistaken, the FFR Cobra's use a 90" wheelbase as I recall.

The big difference between the n/a and the blown version of the two engines is the low speed torque of the PD blown version - it is stunning! BTW the Eatons (either one) can be had much less expensively than the Centri and all the pieces needed to make it work. In as much as you already have a Cobra Engineering Blower Adapter Kit for the M122 GT500 blower you can easily find one of the GT500 blowers on eBay in the $600 / $700 range or so if you are willing to look and wait. The Blower Adapter plate will also accept a TVS blower if you stumble across one of those at an attractive price. Bang for the buck the M122 GT500 blower is extremely hard to beat and it will easily eclipse 600 WHP so it is not necessary to turn the wick up to hit your power goals.

Here is a link to a clean GT500 blower for under $800 => GT500 Blower.

Because the auction will eventually close and the image will disappear I added the screen shot below for future readers;

Product Font Screenshot Parallel Technology


When you build a blown version of these engines you can but should not cut corners on internals like fasteners, rods, pistons, pins, rings etc. If you do they will come back and bite you hard, right in the wallet.

Ed
 
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