993_Pilot

The 4.0 liter sounds promising. I am mostly interested in the 9M version with their heads. 400 na hp sounds like a very worthy goal to me. Now, if only it sounded like a great thing to the wife, I'd pull the trigger tommorrow! I am sure that I will revisit this topic in a few years when my car is due for a top end and the wife is buying her third car since I got my 993.

Geoffrey

The 4.0l engine would be great for PCA club racing since it would run in a class where it would run against anything over 3.4l and would NOT run against any of the 996 bodied cars. It would be quite competitive there.

TCallas

If a F6 (flat six) air cooled 4.0 liter motor was an option then Porsche Weissach (R&D) would have done it. The air cooler F6 is not a good base to handle the 4.0 liters. When I worked with Roock back in 1997, they were trying their best to come up with a larger (than 3.8 liter) motor for the GT2's and let me tell you. I have never replaced and removed so many race car motors at the track in my life. It was like 4 removal and installs a day including some repairs. I was told by the guys at Porsche Weissach that this power plant was not capable of handling those type of forces thermodynamically and something else was on the way. In December of 1999, Joel Reiser and I were invited to Weissach to see our new GT3R which had the water cooled unit. Now that's capable of handling the 4.0 liters. Back to the 993's, I have been studying up on the 9m units and they appear to be a very high quality part and have a good reputation to far, let's see after some track use comes to play. Don't think that that would have nothing to do with a street car because everything on the track happens later on the street hence the old Porsche saying, "Race on Sunday and sell on Monday". OK Rich, nice meeting you. I would research the Supercharger aspect but make sure that it's a good option first. I like Chris' idea of the gearbox work, that's one of my choices but most of all I would recommend either a GT3 or a Turbo in the end to save you a lot of money.

Martin S.

the truth as I perceive it. If you want 400 reliable HP, get a 993/996TT or a GT3. I believe that nearly every $ you put into an engine mod, other than a factory 3.8 kit or one of Steve Weiner's chips, will decrease the value of the car when it is time to sell.

The gearbox solution is excellent, it ain't cheap either....here is how I have addressed the need to mod my 993 engine and tranny. It is very simple: I won't do it, period. I have learned to live with what I have. Not to say that I didn't put coilovers and big bars on with monoballs...I had to get rid of the SUV ride height.

I do take my 993 to the track from time to time, and I have learned that the car is not the limiting factor, I am. As I get better skilled at driving, voila, the car gets faster...what a concept! Note: I have made great leaps forward with Hoosier and Hankook tires...its the tires that are the major improvement over the RA-1 tires. They inspire confidence.

For those that want to mod their engines and trannys, more power to them. Any mods I do will be reliability mods, the ones that Tony recommended at his recent 993 Tech Session. When I can drive the car to its maximum potential...then maybe I'll move up to a GT3...I don't see that happening for a while

Rick Lee

When I was at Ruf in Germany I saw them working on a 3.2 Carrera engine that they said they were making into a 4.0 engine. I probably have a photo of it around here somewhere. I doubt it's cheap.

NineMeister

The theormodynamic issues with respct to a turbocharged aircooled engine are completely different to those of a naturally aspirated engine, so just because a 3.8 litre turbo race engine is not reliable does not mean that the atmo engine will suffer with the same issues. Specifically these 600hp 800Nm GT2 engine suffered with head leakage problems due to the high cylinder pressure, the effect of which produces said 800Nm of torque. In contrast, if a 4.0 litre atmo engine produces say 500Nm, surely this just means that the cylinder pressures are 5/8 of that of a GT2 race engine? Similarly if you looked at two identical torque turbo and atmo engines, the thermodynamic loads on the turbo would be significantly higher per cycle than the atmo, one reason being that the temperature of the intake and exhaust are higher. To me this a classic case of misinformation "proving" that something is not possible for the wrong reasons.

In our experience a 4.0 litre aircooled n/a engine is not only possible, it is reliable as well, and here is the dyno result (in comparison with our standard 964 Cup car) to prove it.

901aero

Atta boy Colin!

Rick Sylvestri

Simple soulution.........
Get a used GT3 for 75-80k
No brainer if you want to track / street

Red rooster

Colin,
That is bloody impressive ! Whats it doing under 3000 ? Not a criticism but is that a race motor with no sensible bottom end ?

Geoff

NineMeister

I would not exactly call 470Nm at 4000rpm "no bottom end".....

Obviously this engine with its 8000rpm limit is designed for track use, but we already have made some significant improvements to the exhaust system which has pulled around 100Nm more in the 2000-3000rpm range. In conjunction with a more "sensible" cam we should be looking at a flat 500Nm torque curve from 3500 to 6500rpm.

The engine has a 103mm bore with an 80mm stroke to give exactly 3999.5cc using exactly the same pistons that I have run for over 2 years in my 993RS CS with some success. The crank has been designed as a direct replacement for the GT3 engine as well, so hopefully once the 103 GT3 piston is finished we should be trying a 4.0 litre wasserpumper soon. Whilst on the subject of the GT3, I'll post another dyno curve later of the 9m 4.0 litre 964/993 engine against the GT3 and GT3RS measured on the same dyno.

Monique

I feel the same. The 993 is now a collectible... just note how the prices are firming.

The GT3 is a fab value given it is a kettle Porker

ZombiePorsche44

If you guys want to talk to someone who has done it, call Ken Rumbaugh at Scott's Porsche Parts in National City, CA. Back in 1998, he built a 95 Non-vario 993 motor into a 400+ hp NA 4.0L and stuffed it into a semi-tube frame 1800lb 914 race car.

I drove the car at Holtville (radar gun got me at 172mph down the straight/runway) and can say it's a monster motor with instant throttle response and huge grunt, but it turned out to be very unreliable in the long run with Ken finally switching back to a 3.8L for endurance events.

He now has two 97' Factory Supercup 993's with 3.8's and I drool every time I get near them.

ChrisW. has a very valid point regarding gears & performance increases, back in the old days if you wanted to go faster in your 911SC or early 3.2L Carrera, especially short race courses, you just installed a 7:31 ring gear in your 915 tranny lowering all of your ratios and allowing you to get off the corner faster than any stock tranny.

But unfortunately our trannys cannot be done the same way and gears for these G50's are way way expensive when compared to earlier Porsche tranmissions, but one thing for sure is, the differences in performance are huge and maybe better spent money than a 4.0L upgrade.

ZP44

Red rooster

Colin,
In this part of the world , on ordinary roads 2-3000 is the most used rpm area .

Thats why I look hard at anything that improves torque , especially at the bottom ( 1500-4000 ).

OK, how about emmissions compliance for the British MOT on a cat car ? or is that where the milder cam version swings in ?

Geoff

Martin S.

I have stock gears, my neighbor has close ration gears and a PMS LSD and nearly identical cars. We both are at a similar level of driving. We have been together at CaliSpedway and Buttonwillow...there was only one spot at Cali where he seemed to get out quicker than me. On the remainder of the track, I was as quicker or quicker. There was no difference at Buttonwillow.

A few months later, my neighbor then did a drag race with another 993 Rennlister who had stock gears, down the front straight at Willow Springs International Raceway...there was no difference in performance one car over another.

What I have concluded is that the short gears make the car more fun to drive around town...you are in the "sweet spot" more often. At the tracks we run in the West, the short gears don't seem to provide the dramatic break through that Urban Legend makes them out to be (The one place where the gears could really help, it would seem to me, an Auto-Cross)

I would think a change in the ring and pinion would be more dramatic...ANDIAL was selling one for about $2,000 + $$$ to install it. But its not my place to make recommendations, only to report what I have experienced.

If one has the budget to do the short gear box and PMS LSD, it is a mod I am certain they will love....I am doing the LSD (Guard) and will live with the stock gears....it's all about the money at my house.

chris walrod

Martin, do you know Eric's 2nd and 3rd gear ratios?