OK guys, for those of you who are looking for pistons or have looked for pistons, you will be familiar with the problem of finding a manufacturer and then getting the specs correctly communicated and finally getting the piston you wanted. Usually things do not go the way you anticipated at first or the process is painfully long with something always just a little bit different than what you hoped for when you finally get the pistons.
I may have a fix for everyone in the next week or thereabouts.
If things work out as currently anticipated (always a challenge) I'll have a piston manufacturer that will be willing to build the piston, the way we all have wanted them built, and all you have to do is specify bore size and compression ratio. The rest will be already done for you, i.e. heavy wall H-13 pins, supercharged ring land placement, proper radial clearance for the rings, a TotalSeal AP Steel ring package, two country miles of PTV clearance, 0.200" skirts and any bore size your heart desires. All you will have to do is identify the piston by name for example XXXX, bore size and compression ratio - that's it!
The pistons will be individually replaceable if you do have a whoops (lets hope not) and the replacement will not require you to rebalance your crank - it will come within +/- a gram of what the original was. If this comes together the way I am hoping, ordering custom pistons will be sort of like ordering lunch in the old days when you could walk in and just say, "I'll have a cheeseburger, fries and a Coke", and you end up with the exact meal you wanted, the way you wanted it.
In a week or so I hope to have a 3D Acrobat image of the piston I can post up on the site here that will allow you to rotate, turn around and see the piston from every perspective. Stay tuned ...
Do we have the option to add a stainless top ring and a napier cut 2nd ring? If so, is there an up charge for those? The price is damn good for custom pieces and came in well under what I was expecting them to be.
Do we have the option to add a stainless top ring and a napier cut 2nd ring? If so, is there an up charge for those? The price is damn good for custom pieces and came in well under what I was expecting them to be.
The only thing I would like to see is maybe a 0.200 or 0.210 thick guy who is gonna lean on it with their high horsepower forced induction builds. I believed it has been discussed already, these are using offset pins....correct Ed?
The pin wall thickness is not hardwired to the 0.180" dimension you can get them at 0.200 and higher by just asking for them. The Turbo guys who spin the motor up to higher rpms will want to go to a 0.200 wall pin like you were suggesting.
At 7500 rpm and below the 0.180" pins will work fine. Remember the pin material is H-13 tool steel. Our stock pins are really meaty but they are made from a lesser steel. H-13 tool steel is pretty impressive stuff. At 8000 rpm operation or higher with either a turbo or PD blower I would go up a notch on pin wall and start to look at the heavier 0.200" wall pins.
I hope you don't either but if you do or if you decide to freshen your engine, I don't think there is a better piston choice available — anywhere at any price.
You are absolutely correct. The stock deck height for our engines is 0.012" These pistons go in at 0.050" or 0.038" deeper than stock. The reason I chose that route is more uniform crown thickness w/o a dish, virtually unlimited PTV clearance for any cam less than 0.525" lift and decent clearance for cams with greater lift.
The PTV clearance, as you have observed from time to time, frequently is the limiting consideration with respect to where you can set your intake centerline. While these pistons do not give you unlimited cam phasing freedom they do give more than most anyone would attempt to use, yourself and Steve possibly excepted :bigwink:
Like many of the piston's parameters if you really wanted to change this, it is easily accommodated by a 0.038" change in compression height. Compression height, turns out to be one of those metrics that Gibtec can easily manipulate.
I should have commented on c/r and dome considerations with the 0.050" deck configuration Tony, apologies but here is a look at what is possible and what it looks like.
A 9:1 c/r actually has an almost imperceptible dish to it. You actually need to use a straight edge across the top of the piston to see it. The piston below is an 11:1 Modmotor piston that is also 0.050" down in the hole. It was made from a particular forging at Arias before we used them all up.
Top view:
Below is a side view of the dome required for an 11:1 c/r.
Side view:
The dome is very broad, but low. I use the entire crown of the piston to achieve the target compression ratio with the least protrusion possible into the combustion space.
The step to 12.5:1 (for the hale and hearty) is only marginally larger than the 11:1 dome. The intent is to use the natural good combustion characteristics of the pent roof combustion chamber design and simultaneously shoot for the shallowest combustion chamber consistent with the target c/r.
With the 0.050" deck PTV considerations do not become a thing of the past but you do have to work pretty hard to create an issue.
Haha, I just came in here to ask about compression ratios and how you achieved 9:1 with basically a flat top. I figured you moved the piston down in the hole a bit and I like the idea since it keeps the crown thickness uniform for the most part across the top of the piston. I usually play in the 10 to 11:1 range with my boosted applications, so this works out well to my advantage, especially in the PTV department.
I know exactly where you are coming from Jim. There were a number of guys who used my older forging based pistons until I ran out of forgings. One of the early design issues I faced was exactly what Tony has pointed out so often - cam phasing limitations driven by PTV clearance limits. By dropping the piston down to get an 0.050" deck height your ability to position the intake cams where you would like them to be is substantially enhanced. Even better it has no impact on my ability to target virtually any c/r.
Many decades ago when I first transitioned from n/a engines to supercharged engines my first one was bought from a professional engine shop up in Taylor Michigan. Although I was smart about n/a engines, at that time I was totally uninformed about blown engines. That shop actually would not build the engine for me until I 'apprenticed' on their F/C for an entire season. As one of the owners and crew chief for the car said, 'you'll kill yourself unless someone shows you what to do and how to do it correctly.' So I got a 1yr crash course on how to build and maintain the engines and car. Imagine trying to buy that today and it was just given away back then!
When I first saw the engine with the heads off, the pistons did not come all the way to the top of block. I was told the reason was exactly what you had picked up on - uniform crown thickness and target c/r. Over the years Detroit has done repeatedly the same thing time and again. In the Ford camp the engine that everyone would recognize that comes with its pistons 'way down in the hole' is the 5.4L 4V. Yup, the big brother of our 'little' 4.6L Terminator engines.
The ability to optimize piston geometry for a performance application and still run the cams where you want to run them makes the increased deck height very attractive. While it can be done for any engine, it is most attractive on pentroof and hemispherical combustion chambers. Both chamber designs have very attractive combustion spaces that lend themselves exceptionally well to this approach.
Update: talked with Nick again yesterday and my pistons should be done this week. Hoping they ship right away and will arrive when I'm not out traveling. Pics definitely will be posted soon!
I was talking with Nick a day earlier and he told me the same thing, Joe. I am as pumped as you are to see the first pieces. Even better in your case, you get to use them
Thanks, Ed - gad you are keeping tabs on them as well. Am definitely looking forward to seeing them and getting plenty of pics. Hope Nick will hook me up with a shirt too, since I was the first order
You want to contact Gibtec directly. Ask for Nick Plantus and tell him you want the blown Modmotor piston that he and Ed designed for the guys on the ModFords website. The phone # is (303) 243-3340. You need to tell him bore size and compression ratio, the rest of the work is already done for you. Nick will check to make sure you have a stock stroke crank and stock length rods and the deal is done.
Because these pistons are true custom pistons you do not have to order in 0.010 or 0.020 bore sizes. You can order any size you want. That is going to provide you a much increased block life over the off the shelf 0.010 and 0.020 bore size limitations.
Exactly what Ed stated. I ordered mine in a 3.555" bore (going in a new Aluminator block), 9.0:1 C/R and that was it. I do vaguely recall mentioning the stock stroke crank and rods, but it couldn't have been easier. You also will have snap rings with the wrist pins, but I didn't ask what the additional cost may have been with the spirolocks. These are promising to be works of art, and I'll have pics up as soon as mine arrive.
Wire pin locs or Spiroloc[SUP]®[/SUP] style locs are the same, cost-wise. I think the operational differences between the two today are all but indistinguishable. The Spiroloc[SUP]®[/SUP] alternative will cost you a little skin and blood in assembly/disassembly and the wire locs will be decidedly easier to disassemble. Pretty much six of one half a dozen of the other. In the end it comes down to personal preference and your personal pain threshold for piston /rod assembly and disassembly.
Here's an update for everyone as the first set of Gibtec S/C Mod Motor pistons have arrived - and they are beautiful! Thanks to Ed for all his efforts since these are everything he promised, and then some.
Here's the box as I opened it up (they also included a nice T-shirt, but it isn't shown) - talk about nice packaging:
I only snapped a few pictures with my phone, but almost didn't want to take one out of the bag. No matter, they are too nice not to share.
The spec card:
Have to make this short since I'm in between some errands but will be happy to answer any questions (although Ed would know the most about these) or get better pictures later. Anyone serious about building their engine really needs to check these out. They'll be on their way to my Aluminator block soon, so stay tuned!
Those turned out just like Nick said they would. That is the finest Modmotor piston you can buy anywhere at any price, bar none! I am quite pleased and at the same time happy for you.
For anyone that needs pistons and you are sitting on the fence this is what you are looking for. There are none better, anywhere at any price.
Those turned out just like Nick said they would. That is the finest Modmotor piston you can buy anywhere at any price, bar none! I am quite pleased and at the same time happy for you.
For anyone that needs pistons and you are sitting on the fence this is what you are looking for. There are none better, anywhere at any price.
Will definitely do that, Brandon. They are deserving of a background nicer than my garage floor (although it is a sweet floor), so I'll snap some better ones when I get home this weekend!
Nice! Three pics is a tease - we need more. Piston porn FTW! Lol.:ilovemf:
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