toddk911

The biggest limiting factor for hp/boost in this car is octane.

These motors in stock form have proven to be monsters running 25psi and 500+ daily driven hp...with race gas/e85.

So to get 400whp on pump and stock internals becomes the issue. So in regards to only pump gas, yes ported head, intake with equal runners, and matched cam will make 400 on pump MUCH easier.

And the details on those internals can great be expanded on by Chris or Tom.

Of course as also mentioned, the 3.0L is a very easy, but costly, solution to 400 reliable whp on pump.

Tedro951

The reason people keep them at 350 rather than 400HP? This will result in me being flamed, I'm sure, but 350RWHP isn't exactly a grocery getter. 400 is going to be even more hairy to live with.

300RWHP is the fiesty redhead with natural rack that can cook a little and deliver a performance on fantasy night. Some jewelry and spa appointments will suffice.

400RWHP is the fake boobed blonde that has girls night out twice a week, flirts with the pizza delivery guy, and takes half the equity in your house and 401K when her high priced lawyer gets involved. You'll have to pay for his services, as well as your counsel.

toddk911

LOL!!! Perfect!

Clown: It seems, as Tedro points out, that up to about 300-350whp it is some what cost effective and reliable on a 951. But beyond that it quickly becomes the law of diminishing returns in terms of time, cost and hp results from said time and cost.

So then it becomes a question of "how bad do I want that additional 50hp?"

fast951

I don't even want to know what a 450rwhp will do to you! LOL

Own Goal

Wonder why it is when I read that sort of detailed analogy of cars and women it rings with a tone of life experience? Should I ask what kind of P car did you loose in that first adventure or we just move on now?

jtsporsche

maybe he kept the car and got rid of the woman

Tedro951

Neither. Had the same wife for 20years, I stayed with the same employer for 26 years(retired, and a grateful civilian now), I still own the FJ1200 I bought new in 1986. I'm a little boring, I know!

Lets just say I'm pretty good at learning what NOT to do, and most has been using the search function. :-)

George D

Longevity = good tune with boost around 17psi on pump fuel. Getting 400WHP on a 2.5 using pump fuel isn't going to happen without extensive work and money. You will also be slower than a good running quick spooling 330whp car. Maybe not in a straight line, but in corners, where our cars shine, a quicker spooling car with a good tune is really fun and faster than a laggy big turbo small power band 951.

I just got back from a hunting trip with some friends. I drove a friends 951 on the way home (200 miles) with about 330whp running Vitesse software, a very quick spooling Tial mounted Garrett turbo, good suspension, brakes, and it was really fun. The car had about 240K on this motor with nothing but a ring and bearing job. He is also running a 2.5 N/A head. Amazing. Immediate boost is so much better than lag with these cars.

I've learned the hard way that a larger turbo may make good "dyno" numbers, but that doesn't mean it's faster.

One of my favorite 951's had 330whp at 18 psi with similar tq. This was about 10 years ago running a K27/6 turbo, autothority chips, 3" exhaust, test pipe, stock injectors, etc. This car was fast. The dyno showed max tq at 3500rpm and max hp at 6500rpm. Now, that is a great power band. The dyno chart past 3500rpm was flat. The guy that purchased the car from me drove it another 80K without anything but a new turbo and normal maintaince. He was able to beat Vipers with this car in a straight line, and be even with 911 TT cars. It's now a 3.0 built by LR making many exotics feel slow out in LA.

I also had a 89 951 that put down 430whp and similar tq using a LR intercooler, LR chips, LR super 75, large injectors, etc. That car had WAY too much lag and max tq didn't show till almost 5K. Slow track car. I am now finishing up a 3.0 motor for this car that should see close to 500whp on pump gas at 17 to 18 psi. My goal was to have max tq by 3500rpm and max hp at 6800rpm. The work that goes into the entire car to allow reliable hp over 400 to the wheels costs money, time, and talent from folks that know these cars.

I would recommend you first build a good spooling 300 to 350 whp 2.5 and have fun with it for a while. The factory rods and pistons are fine. The most revelant reason you can't turn up the boost on these cars is that you will out flow the head with too much boost. I'm not an engineer, or even a good wrencher, but I do know outflowing any part of a turbo motor will eventually cause costly issues. Even a well prepped 2.7 N/A head that will out flow even a well machined/prepped large valve 951 head can't keep up with a modern turbo that can easily boost to 30+psi.

Good luck with your project.

Clown

Thanks for the HP+Woman analogy I am still mulling that one over in my head wonder what kind of woman I want to drive. I guess the general consensus is happiness is somewhere between the fiery red head and the blond with the fake *****.

George D and others: Thanks for the tips about staying around 350HP to the wheels. I will consider taking the less exspensive more stock route. I would like to avoid major lag if possible and that is a good point you bring up. I just figured I maybe could get away with more if I upgraded the internals that are over 20 years old and upgrade with newer and stronger components since I had the engine apart anyway. I would think this would make it possible to reach the 400hp threshold.

Thanks for all the tips so far. Yes I plan on staying with the stock 2.5 since it is cheaper. I will look into porting the head. What kind of cam would you guys suggest and where can I pick one up? Any reason to cement the block or anyone tried this?

JDS968

Just think...living with this girl on a daily basis.



Sure, taking her to get the groceries will be fun, but you'd better not mind the awkwardness, you'll get funny looks, and you're gonna be sore by the time you get home

jjmudd

Where did you find a picture of my wife??!!

Own Goal

That's a nice "ride".

Chris White

Ok, here is some info you can use for your decision making – some of it is straight forward and some will get peoples undies in a bunch – its all just my opinion!
Crank – the stock crank is very strong, no need for any mods. Cross drilling won’t ‘cure’ anything. Knife edging will make it lighter (so will an aluminum flywheel)
Rods – The stock rods are very strong – possibly too strong (meaning that they are needlessly heavy). Aftermarket rods are lighter and will stress the engine less at higher RPMS.
Pistons – stock pistons are also very strong…and too heavy. Aftermarket pistons are lighter and will stress the engine less at higher rpm – you can also change the compression ratio.
Pan baffling – next to useless. If you run your oil low enough to expose the pick-up you deserve what happens (this is over two quarts below the bottom of the dipstick).
ARP studs – not needed if the engine management is good.
Cometic head gasket – don’t try it unless you have machined the head and block flat.
Bearing coatings – a good idea with no down side.
Windage tray / crank scraper – both are good ideas – the full windage tray takes a bunch of labor to fit it right.

Stuff you did not mention –
Oil cooler – mandatory for 350+ rwhp. The stock cooler has a hard time keeping up to the heat from a stock engine.
Real Engine Management – once in to the 300rwhp range engine management becomes critical – high output 944 turbo motors do not last long if they are not tuned well.

Other stuff that was mentioned –
“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” sure, why not turn it up to 500hp? 600 hp?

That is because a well-designed system is made up of parts that were designed / selected to run at a certain boost/rpm. ‘Cranking up the boost’ will cause the turbo to operate outside of its peak efficiency range – this will cause the intake air temps to go up and eventually lead to detonation and the need for a new engine.

In reality you should think about 350whp as a reasonable max goal. You can get to that with the right turbo, injectors, wastegate and engine management. You can certainly get more – but you will be playing with a time bomb – one wrong move and it will convert its self to a lump of scored and steaming parts.

George D

Special Tool tried this (cement) on one of his blocks. ST was a guy that showed dyno's in the 600hp range. Granted, at one event he hit around 400whp, and he lost to a 300whp 951 at a 1/4 mile event. If you search, you may see the race. A better option, if you are looking for a stronger designed open deck block is to add a deck plate. I think Garrity has one of his old ones at his shop for his race 951 motors.

I think ST went through two or three bottom ends trying to overcome the fact that his head couldn't handle the flow of air at those boost levels. It's not the ability of us to make a bottom end strong enough to handle 1000hp, it's the ability of our head design to flow the air. EVO bottom ends aren't as strong as ours as stock. Look at our cranks, forged rods, forged pistons as compared to the modern stock EVO or STI. It's their heads that flow enough air to allow nutty dyno runs. This DOES NOT mean a 600WHP EVO is faster at the track than a well sorted 350whp 951. I've owned a 400+ WHP EVO. My old blue 89 951 with 330whp was faster once moving.

Sent out a post to see if anyone in your area will let you drive a well set-up Porsche 951. I think you will have some fun in a 300 to 350 WHP 951 with modern suspension mods. Offer them free pizza and beer. You might have have a few folks show.

Own Goal

That was very good, thanks Chris. So one item you mentioned got my attention. Did most on my build already (motor in connecting lines and more lines now. Goal run and license next month. 25 yrs = no cat in Texas). However, got my attention on the oil cooler thing. I've cleaned and check my stock one but it's Texas, a street car and I am keeping my AC. Might care to suggest a replacement oil cooler?