What kind of power can a Mighty Max bottom end make?

[uummm]

I have a 91 Mighty Max 6 bolt wideblock 4g64 motor. I plan on using a DOHC head on it and putting a turbo on it (this motor is for my RX7 project). My question is how much power can the stock pistons and rods hold up to? I have seen some cars on here with the SOHC motors making good power on a stock bottom end in galants and eclipses but I think the pistons may be different in the truck motor. I'm hoping to make about 300hp for a while, as I plan on replacing the bottom end with forged internals when my budget allows (my ultimate goal is ~500hp eventually), which is still a possibility before I get the car completely together as it is going to be a long project. TIA for any insight.

 

[jayson427]

I think it could handle 300hp until you rebuild if all the matinence was maintained and runs good.

 

[uummm]

I got it from a junk yard and they said it was used in their yard truck for a couple years and ran good. at the very least it is going to get a set of bearings and rings and a hone. I have the head off and everything looks to be in great shape.

 

[Cdc1221]

The pistons will need changed to run the dohc head as it will bump the compression over 10:1 on the stock 64 pistons. Better off running the sohc head until you can get forged internals. Crank will be fine though

 

[uummm]

What about if I get a cheap set of stock replacement pistons for a galant or eclipse? Would the compression still be too high?

 

[BoostedTalonTS]

The pistons will need changed to run the dohc head as it will bump the compression over 10:1 on the stock 64 pistons. Better off running the sohc head until you can get forged internals. Crank will be fine though

...also the valve reliefs are in different places for the SOHC 4g64 vs a DOHC 4g64 piston.

That and the Mightly Max 4g64 blocks are wider for the RWD trannys vs the trans-mount tranny FWD/AWD motors

 

[Cdc1221]

...also the valve reliefs are in different places for the SOHC 4g64 vs a DOHC 4g64 piston.

That and the Mightly Max 4g64 blocks are wider for the RWD trannys vs the trans-mount tranny FWD/AWD motors

True, because its an 8 valve.

His motor is going in a rwd car so thats ok

 

[uummm]

So what about using a set of pistons for a 16 valve 4g64 galant? It should put my cr around 9.5, but with a good tune, it should be good for a while at 300hp I would think.

 

[Cdc1221]

Youre talking about high comp ratio on cast n/t pistons, with boost. While its been done, its most definitely not a good idea. Best idea is to leave the stock 8 valve head on it until youre in a position to get forged internals, that way youre not building the engine twice, and risking the build. Just my $.02

Or find a wideblock 4g63, throw in some oil squirters, turbo 63 pistons, arp hardware, and a dohc head, and youve got an easily 400 hp capable engine on junkyard internals

 

[uummm]

The problem I'm going to have with the 8 valve head is I'm probably not going to find a turbo manifold for it. It's a good possibility I will just save for the forged pistons, is there any one peticular brand that anyone recommends or are they all just about the same?

 

[Cdc1221]

Wiseco makes a set for around $400 for the 63/64 hybrid build that could be used on your 6 bolt rods

 

[jayson427]

i perfer JE pistions but its all i have used on my builds.