MAGK944

I know there are lots of turbos out there but has anyone modified the 2.5 to 3.0+ on an na?

It seems that there are many cheaper options now on filled iron sleeved blocks, JE/SBC pistons and offset grinds to get in the 3.2 area plus cheap valve options from stock 45 to 48.

V2Rocket

sometime down the road i am considering going for one of the sid/shawn stroker motors...it has almost displaced my V8 thoughts...~2.8L should be enough for some trouble without having to buy a bigger crank.

catamax944

I am also considering this , i already have a 3.0 crank .
Only pobblem here is finding a good machine shop to do the work.

Jfrahm

Without forced induction you would sorely miss the 4v head and might save a lot of money and trouble just buying a 3.0 4v motor rather than building up a 2.5 2v.

MAGK944

I don't know, there are cheap valve options for the 2v to 48mm and that should be ample. But really bigger valves might not even be needed, looking for more velocity with an na rather than more capacity in the head. Mild porting and stock or a little bigger valves = more velocity = more low down torque.

Same with 3L crank, why bother when an 86 stroke can be gained with a 2.5 crank offset grind + cheap Eagle mitsu forged rods and JE small block pistons.

I've seen 108 bores on iron sleeves and 86 offset grinds on 2.5 cranks over on the turbo boards. That's 3.15L

Looking for cheap here, na folk are cheap!

MAGK944

So I have to presume from response that no one has created a 3L+ from a 2.5L SOHC block. Surprised, I would have though with the availability & cheapness of the blocks and parts I would have seen a few here.

Final bump for comments...

Dougs951S

I agree, a 3.1 liter big 8 valve high compression n/a motor would be a lot of fun, but its still not really cheap in the context of an N/A 944. It might be interesting though to do a lower compression 3.1 liter build and supercharge it. To me, you'd have to compare it to a v8 build. I honestly feel I could build a 3.1 liter supercharged car for less money and hassles than a v8 swap, and it would have similar power. I'd fly cut the pistons and then you could have it be non interference as well.

Dougs951

Hit up Michael Mount, if someone has done it , he has.

MAGK944

Yes supercharging would be great but I think a lot of fun could be had with just a 3.1na, high compression and a tuned MAF. Cheap? Well that is relative, iron sleeves, GM pistons, Mitsu rods, custom na-tune, maybe $2.5k, add dfus, maybe another $500, probably around stock early turbo performance in a much lighter car.

Dougs951S

Yes, but once you are MAF'ed and the motor is built, going supercharged only adds another ~350 dollars to the total cost for injectors, a 3 BAR FPR, the blower, metal to make the brackets/plenum, and an old manifold to hack up. Run it on E85 and leave the compression ~10:1 and you could easily make ~350 rwhp. Oh yeah, don't forget the 951 bellhousing/clutch fork/flywheel, tranny, and new clutch you'd then need.

Mueller944s2

This right here, I agree. I think if the power could've been had reasonably from the 8v na then Porsche wouldn't have gone to the 16v. I think overall it'd be cheaper to go with the S2 engine than to build a custom 8v, and the power is already there.

Arominus

I think a stroker 2.5 with the S head would kick *** too. You could also have a lot of fun with a 3.0 block 2.5 crank and the s2 head If you get it to rev more.

blown 944

I can't think of anyone that has done it already, however, Josh has talked about doing a 3.1 with a 94 mm stroke.

I think many would be surprised at how much torque the added stroke makes.

Shawn has driven his stroke 3.0 crank motor and has commented repeatedly about how for a fun, quick car that it really doesn't even need boost.

You could look at his dyno charts to compare his low rpm torque to a 2.5.

I know that my stroked crank made my laggy turbo feel very drive able. And that was only a stroked 2.5 crank. I havnt went with the 94mm stroke yet, but based on my gains I'd say it would make a VERY noticeable difference.

Jfrahm

Can you run longer piston skirts in a stock 3.0 or a stroked one? I am unnerved by the short piston skirts in the 3.0 motors, from the standpoint of knock and boost tolerance.

Van

I think you're low on the price here. It's $2k just to fully rebuild a 2.5 with stock parts (water pump, clutch, gaskets, bearings, rings, belts and pulleys).

944 racers put $5-8k into their engines to get a few more HP...

With your list here, it's about $600-800 to sleeve a block... $1k for a 3.0L crank, probably $800 for custom pistons, another $500-$1k for head work, then the $2k in all the stuff for a stock rebuild! For $6k, you can buy a 951 that already drives... Might as well do nice rods and headers, too. And maybe individual throttle bodies for the intake manifold. So you're at $10k!