NineMeister

In total output (i.e. absolute engine power rather than specific hp) it outperforms all the standard GT3's & GT3RS engines that we have tested on our dyno.

The engine made its power through 100 cell cats and is just about UK emissions compliant and in actual power is actually up there with a typical GT3RS Cup engine, which of course runs with open exhaust and is not emissions compliant.

You are correct, if used flat out all the time it will not last 200 hours, however neither will any engine that Porsche have ever made. This raises a valid point regarding rebuild costs for race teams though. Typically in the UK teams are being quoted £14000 a time ($20,000 ish) to rebuild GT3 race engines every 24hrs, whereas this motor can be rebuilt by anyone who can assemble an aircooled engine, a typical interim 24hr rebuild (bearings, valve springs, rings) and will thus cost less than £5000 a time.

It's not a road engine and was never designed to be one, but it will make a very effective club race engine for someone wanting to be as fast as the GT3 boys and not have to pay the price. As an aside, we are actually considering fitting the engine into a GT3 chassis in order to save weight gain overall performance.

akolodesh

Colin -
I understand that no engine can perform at full capacity for an extended period of time without a rebuild but how do you think you parts stand up to OEM? If I use the car on both the street and track (DE's) (70%/ 30%) - how long can I expect to go before needing to open it up again?

NineMeister

Unfortunately this engine is really more like 90% track and 10% street. If you can live with it depends on how you define radical, certainly it does not lack street driveability (can the moderators let me know if I can post the dyno result?) since it easily outperforms the stock RS engine in every way from 2000rpm up. I can and do drive it to the occasional event with a 4-puck sintered clutch with no issues, with a standard clutch it would be a breeze.

That said I doubt that many regular 993 drivers would be happy to commute with it on a daily basis because the radical short skirt piston design is noticeably noisy during warm up and idle and you cannot use more than 60% throttle below 2000 rpm in order to avoid piston slap. Incidentally the individual throttle bodies cause no problems whatsoever, we use a vacuum balance plenum with the original idle air valve and find that the engine will drive the car on idle in 1st & 2nd gear. Maybe you could live with it, the only downside is that you will need to work with someone talented on the engine management in order to get the emissions acceptable for your own country/state.

The engine has proved that the heads are working effectively, so the next stage of the plan is essentially to dumb-down the design to use conventional length pistons on standard length rods and then re-tune the cams/intake to make peak power below 7000rpm. Since the engine still makes over 400bhp at 6900rpm, even with a compromised piston and 100/102mm bore it should appeal to the club racer as I suspect that a 3.6 will still make 370bhp. In this form with a sub 7000rpm limit it should last as long as any other 3.6 aircooled engine since there are very few modified moving parts and the bulk of the power is coming from the matched head & piston. At the moment we are using chilled-iron forged cams from the original supplier to Porsche, standard 8mm stem 993 valves, and lifting them with standard 964 followers. The only custom items in the engine are the valve springs & Ti retainers, new sintered valve guides (last way longer than copper-berylium type alloys), Carillo conrods and the 103mm pistons & cylinders.

Red rooster

Colin ,
Thanks for that. "vacuum balanced plenum " is a std 272 993 inlet?Sorry to keep firing questions at you but this is interesting.
Geoff

Toga

Very interesting! Thanks for all those explanations.

NineMeister

The engine runs individual throttle bodies, which as we all know traditionally the adjustment sensitivity of this set up causes idle smoothness issues. We got around this problem by linking each intake stack under the throttle plate to a small tank (the idle plenum) using large enough diameter tubing. This balances out individual cylinder flows and with the stock idle control valve feeding into the plenum allows regular control of the idle speed. The engine on Motec idles smoothly between 830-850rpm.

NineMeister

Since there is a little scepticism about the power level achieved, maybe someone out in Rennland could translate these performance figures I obtained at this weekends sprint meeting. I ran a GPS datalogger for one of the runs (Race Technology DL1) which gave the following GPS mph data from a standing start:

0-60mph 4.53s
0-100kph (62mph) 4.70s
0-100mph 9.53s
0-200kph (124mph) 14.52s
1/4 mile (actually 1321ft nearest measurement) 12.74s @ 116mph

As you know the car is a 993RS Clubsport which weighs in at approximately 1250kg with driver (me), runs Kuhmo soft compound road legal tyres. I should add that the conditions were less than favourable, there being occasional drizzle that moistened the track frequently, so I would expect in normal dry conditions that the o-60 time would be of the order of 4.0 secs rather than the 4.5 recorded because the 64ft time was measured at 2.45s rather than my usual 2.20.

I think that these are similar figures to the GT3 RS, does anyone have definitive test data available?

Felix

Colin,

I don't have any figures for a NA car but from another Rennlist thread (https://rennlist.com/forums/993-turbo-forum/173419-60-130-mph-new-performance-measurement.html) I've extracted the following times:

For Car and Driver 60-130 MPH:
993TT: 13.4 sec
993TTS: 12.2 sec

Your 60-124 mph time is 9.99 secs which compares rather favourably with the above times.

From another post in the same thread 100-200 kph:
911 3.8L RSR 12,3
968 Turbo S 11.9 sec
964 3.6 L Turbo ( factory tuned at 0.93 bar boost) 10,4 sec
buggati EB 110 10,4 sec
F 355 11,5 sec
993 TT 10,8 sec
Mc Laren F1 6 sec
Heavily tuned 968 Turbo (RS) 7.95 sec (at 40 degree celsius)
Viper SRT 10 (505 HP) 9,5 sec
GT3 RS 9,3 sec (factory car with more HP)
911 GT1 6,6 sec
Tech art 996 TT 530 hp 8,5 sec
Carrera GT 6,4 sec

Your 100-200 kph time is 9.82 which puts you in the right part of the above crowd.

Well done me thinks. Do you have a 60-130 measurement from the DL1 that you can post to the above thread?

NineMeister

Thanks Phelix, good work there.
Unfortunately I have not got times for 130mph since on the one run I logged I lifted at 124.7mph in order to negotiate the first bend (Avon Rise for those who know Castle Coombe). I should also mention that there is a flat-out right kink 2/3 up the main straight at approx 110mph which may affect the time slightly.

Since you appear to be on a roll, these are the full times to 120mph (should anyone wants split data in km just ask):

30mph 2.25
40mph 2.84
50mph 3.47
1st to 2nd change at 50.6mph
60mph 4.53
70mph 5.43
80mph 6.38
2nd to 3rd change at 81.5mph
90mph 7.93
100mph 9.37*
110mph 11.60
120mph 13.56
*mis-calculated the data in last night's post.

I think I will accept a gracious defeat to the Maclaren F1 and the Carrera GT, although I suspect that the factory GT3 you mention was on wide slicks and hence posted a 0-60 time of 3.2 seconds, whereas I has wheel spin all the way through first on road tyres and could only hit full throttle in 2nd.

Rassel

Check:
http://www.spezialmotorer.com/
There you'll find a 3.2L with 418hp, with carbs and mufflers.

Jean

Colin,

I have been following this thread with a lot of interest. I think that what you have achieved with this 993 is simply great.. I do have a few questions, I will try not to make this post VERY long.

I have hard time understanding why you dyno your cars in 6th gear. The most accurate measurement for your car is in 5th gear, the closest to a 1:1 ratio. Since you have a rolling dyno, not engine dyno, doing a dyno run in 6th could change your conversion factors by up to 15% when taken back to FWHP, other than the transmission correction factor, which is already there..

Now to numbers. Your accelration numbers are indeed excellent. One thing we have to keep in mind is that your gearbox is not standard, therefore comparison to a 993 Carrera would not be accurate. If HP is shown through like to like acceleration comparison, let us discuss it:

If you have the stock Clubsport gearbox which has shorter 3rd, 4th., and 5th gears, then you have your speed limiter set at 7700RPMs at least (you said you achieved 190mph on your dyno). This will make a big difference when it comes to acceleration figures, as you have a killer combo for acceleration figures, here is why:.

Assuming you have a stock Cubsport gearbox, Your have reached 0-200KPH in 4th gear (1.241:1 ratio) instead of 5th gear. If you rev limiter was set at 7200 RPMs, you would be shifting to 5th, loosing around 0.5sec and getting around 15 seconds to 200 KPH (125mph) and 10.3 seconds 100-200kph.

Let us see how your numbers compare to the cars with closest accelration and for which we know the weight:

9Meister: 414 BHP, 1190 Kgs (est.): 9.8 Seconds: (2.87Kgs/hp) in 4th gear
964 Turbo: 381 hp (est.@0.93bar), 1470 Kgs: 10.4 seconds: (3.9Kgs/hp) in 4th
993TT: 408 BHP, 1580 Kgs: 10.8 Seconds: (3.9 Kgs/hp) in 5th. gear

Obviously the numbers above do not match up. 2.87 Kgs/hp vs. 3.9 Kgs/hp (36% better) and 1/2 second difference (5%)? Let me explain:

The 993TT will reach 124mph (200KPH) in 5th gear, which is one gear change more than the 964 Turbo, if we can agree that a gear change is around 0.5 seconds, then the 993TT and 964 T are very close, 10.3 vs. 10.4 seconds from 100-200 kph each. The weight/hp difference is quite similar and the accelration numbers are the same. If you had a normal rev limiter, you would have hit the 200 kph in 5th, which would be around 10.3seconds.

Based on the above, I estimate your car to be having a ratio of around 3.5Kgs/hp at best, therefore your BHP is around 340 hp. I know it sounds low, but acceleration numbers are hardly wrong. Some factors can affect them of course, slipping tires, not perfect shifting etc.. but they cannot be very far off with similar cars.

I might be wrong, but I don't think I am far off, based on all the numbers we have seen on that acceleration thread that was linked.

Please take this as a healthy debate and not a criticism, I might be missing something.
Regards,
Jean

NineMeister

Jean,
I appreciate your thought and interest in the figures and will take your comments constructively.

The car has a stock RS CS gearbox and is running 285/30 18 rear tyres, the rev limiter is set to begin at 7800 and I was using all the revs. As mentioned I suffered severe wheelspin in 1st gear due to a damp track, from experience I would guess that this cost around 0.3-0.5 seconds to 60. In addition to this I also negotiated a 0.6g bend at 100mph during the run. I am also running a CS wing at full downforce.

Dyno testing is done in 6th gear to minimise rear wheel torque, in 5th gear it lights up the tyres and I prefer not to strap the car down to the floor as we see inconsistent results. Three weeks ago I tested a 2001 996 GT3 Cup car on the same dyno in 6th, it recorded 385bhp, similarly a 2004 GT3RS tested in 6th posted 407bhp back in March. Comparing like for like, I am comfortable quoting the figures I have measured.

Jean

Colin,

Thanks for confirming that the rev limiter is set above 7700RPMs, then my theory of 4th gear holds.

I am just going strictly by the acceleration numbers you posted, I was conservative to take into consideration the issues you posted as well during your run. My actual numbers would show 320BHP.

As far as the dyno, a stock GT3 RS is 380 BHP (DIN)@7,400RPMs, if you saw 407BHP then it means you were 27BHP optimistic. Still a dyno run in 6th gear does not make sense, and you would not be comparing like for like as the gear ratios are different between the GT3 and the Clubsport (by about 5%). The GT3 RSR is 445BHP for a 3.6 Ltr.

After all the effort you put on the engine, wouldn't it be a better idea to take it to an engine dyno, not a chassis dyno with uncorrected figures, which (again IMHO) don't mean much?.

In any case I think the acceleration numbers show it.
After all Colin, it is not my engine, and what matters is what you believe is correct, I thought I would post my feedback.
Many thanks for sharing all this info, which is much more than what some other share, and being so transparent.

Jean

Christer

I guess if anyone has a standard car with the same gearbox, it could be dynoed as a baseline?

Jean, as an aside - most GT3 owners that have dynoed their cars are actually getting RWHP figures close to what the factory quote as FWHP....

As far as the 'acceleration figures show it' - I do not have the knowledge to agree or disagree. Do you have the acceleration figures for your car? It would be interesting to see how you compare.

Jean

Christer, Some GT3s do have better numbers others don't. I think not enough info to make a decision. I might be wrong. Dyno in 6th gear is incorrect, and comparing cars based on different gear ratios is not very accurate either. Colin should take his engine to a MAHA dyno, or engine dyno.

As far as acceleration numbers, my post above I think shows it, and Colin having the 7800RPM means he is reaching 200KPH in 4th gear.. IMO the numbers of acceleration and weight match up perfectly...

My car did a 6 second run 60-130mph, which would be closer to 5.5 seconds 100-200KPH I think. on pump gas (I estimate around 600+ hp). My engine is not part of the topic however.

I don't have any interest or affiliation with any tuners, I am just trying to debate numbers. Sorry if I sound negative.