993TT -V- 993GT2 power plants

[sleep envy]

I'm following the pissing contest on the other threads with great interest.

One thought which has crossed my mind is what are the differences between the power plants of the 993 tt and the gt2?

Speaking to VS a while back he was getting around about 450bhp from his tt with a different ecu, modified exhaust and std turbos. I understnad that to breach 500 bhp the bigger K24s are needed (along with high flow rate injectors) but what are the other spec changes to make this leap?

I'm asuming that the basic spec of the engine is the same for both variants.

[993rsr]

Difference between my 1998 GT2 and a 993TT engine are:

Manual tappets (some 993GT2's had hydraulic tappets)
Different camshafts
Different timing gear
Lower compression ratio (to be able to run more boost)

Everything else is stock 993TT.

[flamespitter]

I always understood there was rather more 'commonality' between the 993 tt and the 993 GT2 powerplants than most GT2 owners would care to admit.

1.ie basic 993 tt=408 bhp
2.Factory power increase=430bhp consisting of second oil cooler and new ecu (standard k16 turbos)
3.Final factory upgrade , 450 bhp consisting of the second oil cooler oil cooler (unless car already in 430bhp spec),new ecu, k24 turbos, gasket set and cosmetic quad exhaust pipes.

1995-1997 993 GT2, as point 2 above,ie 430 bhp
1998 YM GT2 sometimes referred to as an 'evolution' (but not by the factory), 450 BHP as point 3 above.
The 450 bhp 'upgrade'kit was readily available from the factory at a cost of around £5000 for the earlier gt2's or 993TTs for that matter.

I would be very surprised if there were any other significant differences in the engine bay between the two models, since the road GT2 was not specifically built to race itself, but as a homologation special for Le Mans etc.

Once on the racing track, the differences between the engines are MAJOR!

[clubsport]

Agree....I thought the '98 model Gt2 shared the K24 turbos along with the X50 450 lump of the Turbo S...where as the '96 model had the 430 bhp lump with the smaller blowers.
No doubt the imminent "Big Boxta" owner will be along soon to clarify

[flamespitter]

clubsport said:

Agree....I thought the '98 model Gt2 shared the K24 turbos along with the X50 450 lump of the Turbo S...where as the '96 model had the 430 bhp lump with the smaller blowers. No doubt the imminent "Big Boxta" owner will be along soon to clarify

Absolutely right!
When the 993 TURBO S came out in 1997 sporting 450 bhp, 'aggrieved' GT2 owners contacted the factory to ask why their vaunted cars were less powerful than the Turbo S.The factory confirmed this was merely the earlier model year GT2s and the 450 upgrade kit was readily available for those cars. The early GT2s including all the RHD models were originally 430 bhp motors sharing k16 turbos with the 993tt, although at least one was upgraded to 450 bhp with the kkk24 turbos etc.

[sleep envy]

That's surprising for 2 reasons, I thought the GT2 would be a bit more 'exotic' and secondly just goes to show how engineered the tt lump is.

[MOD500]

Its interesting regards the 430 vs 450 kit, did the reviews 'back in the day' not prefer the 430 for its less laggy, more progressive nature opposed to the rather logic gate-esque hit of the K24 equipped car?

[silver993tt]

sleep envy said:

That's surprising for 2 reasons, I thought the GT2 would be a bit more 'exotic' and secondly just goes to show how engineered the tt lump is.

Well, the GT2 was alot lighter and this was helped by the 2wd and more basic interior.

[flamespitter]

I think the 993 turbo engine must surely rank as the finest Porsche turbo engine so far.Its derivatives raced with great distinction in the GT2 classes, it has been tweaked to obscene power levels, and I am not aware of any horror stories on these engines.I dont think the same can be said about the water cooled versions.

[glenn mcmenamin]

flamespitter said:

I think the 993 turbo engine must surely rank as the finest Porsche turbo engine so far.Its derivatives raced with great distinction in the GT2 classes, it has been tweaked to obscene power levels, and I am not aware of any horror stories on these engines.I dont think the same can be said about the water cooled versions.

what about the GT3 lump ????

[flamespitter]

glenn mcmenamin said:

flamespitter said: I think the 993 turbo engine must surely rank as the finest Porsche turbo engine so far.Its derivatives raced with great distinction in the GT2 classes, it has been tweaked to obscene power levels, and I am not aware of any horror stories on these engines.I dont think the same can be said about the water cooled versions. what about the GT3 lump ????

Sorry, didn't realise the GT3 lump was turbocharged.

[glenn mcmenamin]

flamespitter said:

glenn mcmenamin said: flamespitter said: I think the 993 turbo engine must surely rank as the finest Porsche turbo engine so far.Its derivatives raced with great distinction in the GT2 classes, it has been tweaked to obscene power levels, and I am not aware of any horror stories on these engines.I dont think the same can be said about the water cooled versions. what about the GT3 lump ???? Sorry, didn't realise the GT3 lump was turbocharged.

Oh yes, d'oh !!!


G.

[flamespitter]

And to nicely round of the point so we all remain friends,surely the GT3 in all its forms will go down in history as one of the all time greats !!

[abarber]

flamespitter said:

I think the 993 turbo engine must surely rank as the finest Porsche turbo engine so far.Its derivatives raced with great distinction in the GT2 classes, it has been tweaked to obscene power levels, and I am not aware of any horror stories on these engines.I dont think the same can be said about the water cooled versions.

Is that really the case? I thought the 965/Turbo II had a much stronger bottom end??

[flamespitter]

Much of the lower end is actually 964, if you look at the engine parts!

[domster]

abarber said:

flamespitter said: I think the 993 turbo engine must surely rank as the finest Porsche turbo engine so far.Its derivatives raced with great distinction in the GT2 classes, it has been tweaked to obscene power levels, and I am not aware of any horror stories on these engines.I dont think the same can be said about the water cooled versions. Is that really the case? I thought the 965/Turbo II had a much stronger bottom end??

I believe the stock 964s had stronger bottom ends than the stock 993s, but IIRC the 993 Turbo and GT2 used the 964 bottom end, as does the GT3 these days. Could be wrong tho'; I'll try and check with the tech.

[abarber]

Dom,
Looks like it's been discussed at length on this thread: www.pistonheads.com/gassing/topic.asp?t=231907&f=48&h=0&hw=rods

Cheers,

Al

[bergmeister]

Gt2 engines also have differant cams with higher valve lift and longer duration/overlap.
Also slightly larger throttle body.
I have the cam profiles of standard and gt2,can see if i can post on here if interested.
Its not only the engine power,the gearing is differant also,if anything a little too close together and could do with a taller 6th.