Clown

I am rebuilding a 951 engine and am seeking 400HP to the wheels. What kind of Internal Modifications are needed to atain this goal while keeping the stock 2.5 displacement? This is a street car and race fuel will not be used. Is there any one who has gone down this road and can lead me in the right direction? Thanks!

95ONE

I ran 400 WHEEL hp for a while before blowing a very old headgasket. But.. I would prefer to use a 3.0 liter block since it has a thicker deck. Which of course.. I am doing.

hevquip

i'd say use the search function, but i'm too lazy to use it myself to find out info on this as well because it's something i've become interested in lately. i will be buying a 2.8 or 3.0 liter conversion, but if that falls through, i'm going to stick with a 2.5 and mod it.

User 41221

None. A stock shortblock will support 400hp. The trick to longevity will be controlling your A/F mix.

Van

I'm sure Chris White or Lindsey or SFR could set you up with a crank, rods and pistons. They all take credit cards.

kev951

wossner pistons for alusil bore(made in germany and cheaper than mahle, got mine from Karl @ racers edge, recondition rods and use arp rod bolts, balance the entire rotating assembly, oil pan baffle and pickup mod, and crankscraper. if your going to track her hard, also use arp head studs, you can also get calicoo coated rod bearings if you want to as well as the mains, you can cross drill the crank as well, for the main and the rod bearing journals, and if you want to, you can knife edge and nitride your crank , but thats more for making serious power and turning hight rpms, its really comes down to how deep your pockets are, and it can get really really insane once you start talking about sleeving and going dry sump.

what turbo setup are you using?

Chris White

That’s a trick question!
You need to tell us how you want to use the engine. 400rwhp for the street requires no internal mods. There are some that can make the engine work better but they are not ‘required’

400rwhp for a track engine is a very different thing. That would require a lot of mods to make it work for more than 30 minutes!

Dea_944t

Interesting, what would you consider to be max rwhp and rpm for a car used as track-day car (each session max 40 min) with stock internals (camshaft not counted as internal).

/Dea

toddk911

+1

I am about 400 and bone stock internals other than ARP head studs.

Own Goal

Starting with right question. Know what you are going to use it for and what target for power is. I was here about 2 years ago and before the tear down and read a lot on here. Chris above is the guru I think on builds. My goal was street car with 350+ just fine. For what it's worth; stock pistons but steel cyl ( had to do something, they were worn), ARP rod bolts, everything balanced, friction coated, new stock head studs, deck and heads surfaced, stock gasket but invest in a Lindsey steam vent kit to avoid (hopefully) the #4 head gasket issue. No windage tray or scraper since don't intend to track. Vitesse stuff up top. Do have a wideband AF and Tial wastegate has a very weak (3#) spring should I get stupid on break in.

Clown

Let me first say Thank You for all your responses. My first posting here and did not think I would get any responses. What a great Porsche 944 community we have here!!!!

Sorry for the TRICK QUESTION...I take back the word "REQUIRED". How about "what is recomended for longevity of the engine?"

I have read each post and have taken everything into consideration. Let me try to help you all understand where I am headed with this project.

1. I have a pretty much bone stock low mileage 951 with 50,000 original miles. The number 2 bearing spun as they often do and I have the engine in my basement and am preparing for the rebuild.

2. I plan on useing regular pump gas not race gas as this will be a Street Car and not taken to events.

3. With that said, I do have a lead foot and tend to drive my cars hard on the street when I am safely able to do so of course.

4. So with the above factors into consideration I am looking for reliability and strength.

Also is it just me or do most 951 owners max out there cars around 350hp to the wheels? Linsey also offers a 350 RWHP kit why do they not turn the boost up and run 400HP? What I am getting at is, in order to turn the boost up won't the internals need upgrading to keep reliability?

I am getting different opinions here: Some say Stock is fine others say different?? I don't have an unlimited budget but am looking to fix things while I have it apart. Remember I am seeking 400 to the wheels not crank.

I was planning on stock pistons, new stonger aftermarket Rods , Knife Edge and cross drilled crank, Oil pan baffle and a stronger aftermarket head gasket. Are the ARP head studs necessary? Also any of you cement your block?

As of yet I have not settled on the Top end performance upgrades such as the turbo, AFM, etc. as of yet and any suggestions would be greatly appreciated!! One step at a time right???

David Floyd

[QUOTE=Chris White;8131548]That’s a trick question!
You need to tell us how you want to use the engine. 400rwhp for the street requires no internal mods. There are some that can make the engine work better but they are not ‘required’

400rwhp for a track engine is a very different thing. That would require a lot of mods to make I
t work for more than 30 minutes![/QUOTE

Agreed.....and 400rwhp on pump gas is a harder to reach than most think.IMHO

Clown

Ok, ok, all you who say Stock Internals for 400rwhp is just fine (95ONE, sh944,Chris White,toddk911) let me ask you these questions....

What is the max HP for stock internals?

Where would you dare to go with your boost?

Maybe my goals are too low for the 2.5 Turbo. Should I be shooting higher with the modifications I am currently planning?

Thanks again for your input.

Own Goal

suggestion; I think that 350 deal is about getting the "easy" horse power. some have gotten a lot more but you want a driver. Before ever got into this project did a lot of research. Go to the HP/Weight/performance webb site (sorry, new computer and lost the link). Figure what you want it to do in terms of 0-60, ET / trap (must define performance even if not for drag). You know the weight wet with driver and it will tell you what you need to the ground. I think you will like 350 just fine if run the numbers. Must also remember stuff like 93 octane is about best we get now days, really don't want more than 1 bar for a driver (do we?) etc. Plan the build before spend $1. Then watch on here for deals. Except for the short block and machine work most of what I have collected has come from Rennlist members. Slow but great savings and helping out folks that are needing to dump some extra stuff. Never got anything but straight deals from Rennlisters.

Own Goal

Oh, one more. Once go past that 350 level most suggest a really serious clutch like a Kennedy or such. A stock Sach is way easier to drive on the street. The guys that really build those cars could probably tell you more but made my decision easier. FYI: went with new 951 spec Sachs, after market 930 disk (Zimms) and Aluminum flywheel. Hope like the flywheel, better rev but not so much fun in traffic I hear. A lot of decisions once start the rebuild to consider.