Help ! 997 GT3 BHP

[pip333]

Hi guys, took my 997 GT3 Gen 1 to a well known rolling road today, but something rather strange/worrying came up .

The car was running really well, actually showed a few horses over the stated 409 BHP , BUT there's a significant dip in power at 7600 where the peak power is supposed to be.At 7600rpm it's showing under 370 BHP :-(

Any ideas and help appreciated.

Thanks :-)

[edc]

What did the dyno operator say? Was it wheel spin? What about the afr plot?

[pip333]

Hey EDC, thanks for your reply.

The operator was pretty flummoxed too, didn't really much of a clue. It wasn't wheel spin though.

Afr plot shows the same dip :-(

[arcamalpha]

How many pulls did they do? Might be heat related.

[pip333]

Hey arcamalpha, he only did 2 and this graph was the first run...:-(

Quite worrying really, a lot of lost horses where the peak should .

Edited by pip333 on Tuesday 23 September 20:23

[nightwalker]

Probably ignition being pulled for some reason, perhaps not enough air flow cooling things?

[Vixpy1]

edc said:

What did the dyno operator say? Was it wheel spin? What about the afr plot?

Twas me, AFR is a straight 12.

Bit flummoxed as I've not done many 997 GT3's and cannot remember what the curve is supposed to look like!

[pip333]

Hey Charlie :-)

To be clear I'm sure it was nothing wrong with the rolling road session : I'm really after any info on what might be wrong with the car ... :-)

[Cunno]

Google images will give you some reference curves. Standard power on a Gen 1 is 415hp. How was the car cooled when on the RR?

[Cunno]

Google images will give you some reference curves. Standard power on a Gen 1 is 415hp. How was the car cooled when on the RR?

[pip333]

Hey Cunno, I tried looking up the curve but there's such a confusing amount on google .....

The cooling was pretty good I think , massive fan cooling the car...

[Cunno]

http://www.6speedonline.com/forums/gt3-gt2-gt/1059...

Power curve on this thread. Cooling 911s on rolling road is always an issue were the fans at the front? See what Manthey do on this thread
http://rennlist.com/forums/997-gt2-gt3-forum/47953...

Do you have after market air filter or exhaust?

[Cunno]

http://www.6speedonline.com/forums/gt3-gt2-gt/1059...

Power curve on this thread. Cooling 911s on rolling road is always an issue were the fans at the front? See what Manthey do on this thread
http://rennlist.com/forums/997-gt2-gt3-forum/47953...

Do you have after market air filter or exhaust?

[pip333]

Hey Cunno,
Many thanks for the links , will have a read.

The car is bog standard no after markets mods of any kind .

The massive fan was blowing over the front of the car so I assume would be ok?

Even if not wouldn't it affect more of the curve than just that part around 7000-8000 rpm ?

Edited by pip333 on Tuesday 23 September 21:39

[Cunno]

Don't disagree there appear to be a big leap in power at the very end which is odd. Can you feel this when driving? If not more likely to be RR than the car.

[Cunno]

Don't disagree there appear to be a big leap in power at the very end which is odd. Can you feel this when driving? If not more likely to be RR than the car.

[mollytherocker]

Do you feel it when driving?

[996TT02]

Will the real Cunno please post once?

[pip333]

Hey guys, tbh I haven't had it long enough to really be able to say that I can or cannot feel it.

Will be quite tricky I imagine to be able to feel anything unless I'm on a track I guess.....

[Steviebeee]

I had mine on a dyno early this year. Bit of a dip before the vario cam starts at 4800rpm, then a straight run up to the limiter. Will try and post tmr. Had a dip in power with my old 996tt up the range before and was timing chain related.