Engine upgrade 993
Three Wheelin'
Joined: Mar 2002
Posts: 1,548
Likes: 16
From: Belgium
Robin 993, Monique thanks for the infos! Merry Xmas to all!
I'm not sure I would change my car for an RS. If I was single, well may be... The 4S is a good comfort/ hp compromise to have fun and see my wife accept to travel with us. But the same car with more...should I write MORE power! Mmm very tempting! Ok today the price is still a serious obstacle, but I will never say never.
My plans are: next spring test it on rollers and see what are the outputs. Then depending on the value of these, probably go for a valve fine tuning like 993RS talked about a while ago.
This winter, I'm tooooooooooooo busy to work on the car.
I'm not sure I would change my car for an RS. If I was single, well may be... The 4S is a good comfort/ hp compromise to have fun and see my wife accept to travel with us. But the same car with more...should I write MORE power! Mmm very tempting! Ok today the price is still a serious obstacle, but I will never say never.
My plans are: next spring test it on rollers and see what are the outputs. Then depending on the value of these, probably go for a valve fine tuning like 993RS talked about a while ago.
This winter, I'm tooooooooooooo busy to work on the car.
AutoX
Joined: Apr 2005
Posts: 13
Likes: 0
These figures sound great, but I can't help but be skeptical about the torque figure. I believe in the last thread about this build I saw 311 lb-ft?
That's 86.3 lb-ft / liter, an astoundingly high output for an unboosted motor. The best normally aspirated production car (in terms of torque / liter) is the Ferrari F430, which is extracting 79.8 lb-ft / liter. And that's with 4-valves per cylinder. Formula 1 cars, which arguably have the most efficient normally aspirated engines only seem to be able to extract ~90 lb-ft / liter. Any thoughts on how Colin is extracting such world-beating torque from a 2-valve per cylinder 3.6?
That's 86.3 lb-ft / liter, an astoundingly high output for an unboosted motor. The best normally aspirated production car (in terms of torque / liter) is the Ferrari F430, which is extracting 79.8 lb-ft / liter. And that's with 4-valves per cylinder. Formula 1 cars, which arguably have the most efficient normally aspirated engines only seem to be able to extract ~90 lb-ft / liter. Any thoughts on how Colin is extracting such world-beating torque from a 2-valve per cylinder 3.6?
Burning Brakes
Joined: Nov 2004
Posts: 1,169
Likes: 544
From: UK
I was always of the impression that multivalve engines lacked torque, a good example being most Honda engines (no questioning their HP figures, but the torque figures are laughable)
If Colin dares wade in here, I think you will find torque is heavily influenced by gas speeds etc. But I ain't no expert
If Colin dares wade in here, I think you will find torque is heavily influenced by gas speeds etc. But I ain't no expert
Instructor
Joined: Jun 2001
Posts: 216
Likes: 0
From: UK
Colin got as much torque as the GT3 out of my NVR 993 and it doesn't just show this on the dyno, but also on the track using not just my butt dyno but also other drivers butt dynos, pulls like a train, feels like my tuned Golf GTI diesel which is a real torque monster.
Don't know how he does it but the performance is there in the real world (circuit)!
Don't know how he does it but the performance is there in the real world (circuit)!
Rennlist Member
Joined: Sep 2002
Posts: 3,279
Likes: 21
From: Bucks, England
I thought part of our amazing torque was due to the boxer configuration as it's not like we develop much power given the capacity compared to other engines? I am always getting confused as to which gear I am in as it pulls so well.
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Thread Starter
Instructor
Joined: Dec 2005
Posts: 102
Likes: 2
From: UK, Essex
Some of you are asking about torque, the new build feels very strong, i have not lost the ability to trundle arund town in 5th or 6th gear, and from 3000 rpm or so it just takes off. It feels stronger throughout the speed range.
The numbers should say it all;
RPM Old torque New torque
3000 231.9 252.9
4000 251.7 308.0
5000 261.4 314.7
6000 243.3 302.5
6600 222.3 287.5
The numbers are in lbft.
it feels like a super charger.
I will post some photos as soon as i can.
Robin
The numbers should say it all;
RPM Old torque New torque
3000 231.9 252.9
4000 251.7 308.0
5000 261.4 314.7
6000 243.3 302.5
6600 222.3 287.5
The numbers are in lbft.
it feels like a super charger.
I will post some photos as soon as i can.
Robin
Addict
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Rennlist Member
Joined: May 2001
Posts: 4,465
Likes: 129
From: UK
FWIW I don't believe the torque numbers which Colin's dyno (or some other chassis dynos) come up with.
I can only really speak for 993tts here, but when the torque numbers his dyno comes up with for a lightly modified 993tt runing under 1.1bar boost are higher than my engine dyno tuned RS Tuning heavily modified twin plug motor running over 1.2bar (at peak torque) then I can't quite understand it.
Anyway, this is a subject which will be resolved when I get to run against one of his uber torque 993tts
I can only really speak for 993tts here, but when the torque numbers his dyno comes up with for a lightly modified 993tt runing under 1.1bar boost are higher than my engine dyno tuned RS Tuning heavily modified twin plug motor running over 1.2bar (at peak torque) then I can't quite understand it.
Anyway, this is a subject which will be resolved when I get to run against one of his uber torque 993tts
Addict
Rennlist Member
Rennlist Member
Joined: Nov 2001
Posts: 554
Likes: 3
From: Herefordshire
Originally Posted by TB993tt
FWIW I don't believe the torque numbers which Colin's dyno (or some other chassis dynos) come up with.
For a normally aspirated 2 valve, SOHC, single throttle body 3.6 litre flat six to get close to 100 bhp per litre for road use is good in anyone's terms, and I'm as big a sceptic as anyone !
cheers, Maurice
Thread Starter
Instructor
Joined: Dec 2005
Posts: 102
Likes: 2
From: UK, Essex
I too was concerned about dyno claims, that is why i had the car tested before the modification. The only thing that is not fair is that when Colin tested the car before he found that it only made 260 HP becuse one of the vario ram solenoids was not working, he fixed it and the car posted 282 hp. That was on shell optimax. So i am now 100 hp up, so it sould feel fast to me, but the low down pull is also great.
I am convinced that the gain is genuine, and looking at the principal of the dyno, it is difficult to imagine how it could be wrong. It relies on the mass of the rollers, the rotarty version of F=MA (force= mass x acceleration), T=I Alpha (Torque= Inertia x angular acceleration)..... so unless the chaps at Bosch got their sums wrong and my seat of the pants meter is wrong the gains are true.
Robin
I am convinced that the gain is genuine, and looking at the principal of the dyno, it is difficult to imagine how it could be wrong. It relies on the mass of the rollers, the rotarty version of F=MA (force= mass x acceleration), T=I Alpha (Torque= Inertia x angular acceleration)..... so unless the chaps at Bosch got their sums wrong and my seat of the pants meter is wrong the gains are true.
Robin
Rennlist Member
Joined: Sep 2002
Posts: 3,279
Likes: 21
From: Bucks, England
Sorry Maurice, I misread your post. 100bhp per litre is not bad going and a lot of engines acheive it nowadays. I've always thought the 911 to be relatively under-tuned as they come out of the factory.
Cheers,
David
Cheers,
David