So which 4.1 piston is the best????

jason mizel

New Member
Joined
Nov 20, 2007
Hi, I need more information on which piston to run in this 4.1 (291 block) im having built. I've seen guys using the hypers which is what I'm considering too, but i don't seem to know how reliable those things are gonna be
Im just not lookin to spend a bunch of money on custom forged pistons if i can be fine running the h471p's. I know they may work ok but haven't seen much feedback on expected longevity or reliability of them. When its done, the setups gonna have te49,3300 stall,alky for starters. I already have pretty much everything else covered int the fuel pump, injectors,exhaust department. I'm mainly focused also on getting a really good tune for it using plx wideband, scanmaster,and translator. I feel like if i get it running PROPERLY that the hypers should be ok. O only plan on running up to 25lbs probably since its only gonna be a mildly built motor. I know my choices are slim probably, i just dont feel confident goin with the 471p's since they were never really MADE for a turbo application. I know there are other areas on the 4.1 to focus on beefin up so im just goin arp rod bolts, arp main studs, and countersunk the deck for the arp head bolts. Any input would be greatly appreciated, just looking for some opinoons from people that might have run a similar setup before.
 
You know what the bore size is?
Factory 3.965 right now. But we were gonna bore .030 over because those 471p's only come standard and then they start at .030 over. Theres only a slight shadow ring on the cyl. wall so i depending on the piston selection we'll go from there. Not that i think boring out .030 is too much. Its just that the mileage on the block was VERY low or so i was told and im not sure what that faint shadow in the cyl bore makes any difference so i was only lookin to bore it minimally. But at the end of the day its the piston that will determine that due to the lack of choices, or so it seems.
 
Nick Micale has some new J&E's at 3.970 bore. If you could use them he would probably give you a great deal. They are for a 3.625 crank and 5.960 rods.
 
I've run the hypers but you are much better off with some forged ones. That is alot of stall for that small turbo and motor. Spool was crazy on my old TE-62 with a 3200 stall. Running 13psi of boost I was smacking down new Mustangs.
 
I've run the hypers but you are much better off with some forged ones. That is alot of stall for that small turbo and motor. Spool was crazy on my old TE-62 with a 3200 stall. Running 13psi of boost I was smacking down new Mustangs.
Agreed, ive only put 1000 mi on car with the converter and the spool is very fast. I want to run a larger turbo because of the increased displacement as well. Ive ran the 49 for years on the street now and have had good success with it ( never ran at the track) but thonking of going to a 67 possibly.
 
Agreed, ive only put 1000 mi on car with the converter and the spool is very fast. I want to run a larger turbo because of the increased displacement as well. Ive ran the 49 for years on the street now and have had good success with it ( never ran at the track) but thonking of going to a 67 possibly.

If you are even considering going to a turbo bigger than your current one or even running 25psi on your current turbo, pony up the $ and get forged and don't worry about it. The extra $ is cheaper than opening the motor up again. Just my .02

I've seen three TRs opened up in the last two years with fresher rebuilds because of hypers breaking. Wit a perfect tune, you'd probably be fine but one bad tank of gas or an alky bubble in the line and you are toast.
 
I would consider the forged pistons and at least the two billet main caps. They will help insure the longevity you are seeking. You make no mention of a cam choice, and the before mentioned options would allow more flexibility as well.
 
I would consider the forged pistons and at least the two billet main caps. They will help insure the longevity you are seeking. You make no mention of a cam choice, and the before mentioned options would allow more flexibility as well.
204/214 cam
 
Muffin tops are the best to use..
muffin.jpg
muffin.jpg
 
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