Ok... brief history here. We bought a new to us 2011 TTS back in July oh last year, with a Europipe and Sporttec tune installed. We took the car to Cobb Plano shorty after buying the car to have it dynoed. Car made decent power, but we wantred a custom tune... post tune the car made 546awhp and 626lbs/ft of torque! Started drag racing it and times were pretty good, not great, but not bad. Best pass was a 10.98 at 129 mph. Wife's best pass was 11.57 at 130mph!!! In the hot Texas heat in August/September l

Fast forward to this past week. We bought new AMS I/C's and had another tune done at Cobb Plano... car was baselined again BEFORE the new I/C's were installed. (I'll upload the dyno graph)


We took the car to back to Ennis yesterday for our first run of the season at a test and tune post I/C's and new custom tune installed. Weather was amazing with negative DA and cool temps so I was expecting great times from the car. My first pass was a 10.74 at 128 mph... decent et but mph was waaaay lower than I expected it'd be with new found hp and torque. My wife's pass was what piqued my curiosity though. She ran an 11.13 at only 126 mph. She had ran consistently 129-130mph last year, now it slowed down this much? Not saying the tune is the issue, but does it seem on the low side based on our numbers? I think it does.

SIDE NOTE... Yes, I KNOW I RED LIGHTED!!! The guy next to me took forevvvvvvver to stage and I let my frustration get the best of me. Besides, reaction time has ZERO to do with et or mph. Opinions welcome. My pass
Wife's pass

 

Hey Lawrence! So if i understand correctly, before the intercoolers you made 546 whp and 626 wtrq. But looking at the dyno graph you posted it shows a baseline of 502 whp and 609 wtrq. Then the new numbers with intercoolers and tune are at 545 whp and 634 wtrq. If so it seems you were right back to the same numbers previously. Was a boost leak test done before and after installation of the intercoolers?

 

Yes sir, you understand correctly. According to their new owner, former GM... they had their dyno fully rebuilt from the time I had my car custom calibrated last August to now. It supposedly reads much lower numbers now.. obviously from my newly posted dyno sheet it does. Like 40plus hp lower.

As far as checking for boost leaks, they actually broke the plastic inlet pipe ring on installing the new I/C's and epoxied it until we get replacements. Initial dyno it blew the boost inlet pipe off under full load. 😖 Anyway, to honestly answer your question, I can't say I know for sure they did post I/C install. According to their assessment, car is solid on dyno and road tests.

 

Here's the dyno from last August... after purchasing Access Port and having the car custom calibrated. The dyno has since been rebuilt resulting in lower numbers.

 

Ah that makes more sense. I am not 100% but i think i read somewhere that the updated lower intercooler hot side hoses are only available for the 997.1 models. But Sam would know best. Either way, i have a few of the plastic rings left in case you want to have some spare ones for a rainy day. Let me know.

 

Thank you very much! The last conversation I had with Sam and AMS was they're redesigning the hoses and plastic ring issue.... as soon as they're released to market they're gonna send me an updated hose setup. In the meantime, I'm getting new plastic rings sent to replace the broken ones.

Still trying to figure this lower mph issue out, I'm not sure the new tune is making anymore power than before? I supposedly have a peak 23psi boost up from 19.5 lbs I had before the new I/C's. That and moving more air, should make more hp which translates to more mph in the 1/4 mile. Anyway, the journey to find the answer continues. Thanks, again. Talk soon.

Lawrence

 

Did you datalog during your dyno runs?

I did this with my logger during my dyno runs (and also I do it frequently on the street so I know what looks normal) so I could see what the data said.. you should be able to verify boost, lambdas, see how your IATs look and timing, etc. etc. This would go a long way toward figuring out whats up.. I don't know much about the Cobb, but with my tune/logger it's easy to capture.

Also, I had my dyno shop give me the raw Mustang Dyno data files so I could see ALL the collected data, including the WCF, so I could create my own plots of HP & TQ vs my collected data...

Also by logging I could see instantly the changes in my tuners revision (slightly increased load, higher max boost, etc.)

 

This.

I have had perhaps 25+ tunes on various turbo cars over the years,.. and NEVER when done on a Dynojet,.. and only a few times when tuned on a Mustang dyno has have the cars ever held full timing on the road. A check with the tuner in the car,.. on the freeway after is mandatory.

My current 997 was tuned on the road, remotely, by one of the top couple of recommended tuners on this board,.... and even it pulls 5+ degrees of timing sometimes.

That increase in boost you mentioned sounds WAY too big for just inter-coolers. I would have thought 1 psi more,.. and 2-3 degrees of timing.

Nearly all of your power gain would come from the timing,.. and the fact that the air is now denser going into the engine (so you'd pick up MAF grams).

Anyway,.. I'm no expert,.. but my first step wold be to datalog your ignition timing in 4th gear on the freeway. Perhaps romp on the gas pedal a few times in third,.. wind out third and power-shift,.. then hold 4th as long as you can,.. and see what the data says.

The higher gears after being beaten through 1-3 is when the engine is MOST likely to pull timing. It may be that your car pulls nice on the street,.. but falls over in the second half of the drag strip.

 

I did data log at the track... I'm going to send file to Cobb today and have them double check everything. I really appreciate the feedback so far. Btw... this is a TTS, PDK, not a stick car. I hope it's not that I expected too much from this new found "horsepower" but to me if it's making more power, it should translate to more mph on the track. It's definitely not!

 

Feel free to send logs over L. I will help anywhere I can as we have tuned/tracked lots of these and the 991's.

 

Thanks, Sam. As always, I appreciate your input and help.

 

So a couple of guys attribute the lower trap speed to my lower tire pressure... not sure I buy the theory that the car would lose 2 mph on my pass and 4 mph on my wife's pass. Anyway, still sorting this out, I'll keep this thread posted in case anyone is interested...

 

Changes in tire pressure over a very short 1/4 mile shouldn't do much of anything from my testing. I've been all over the board on tire pressure. Numbers didn't change much.


Just throwing something out there....curious, did Ennis change it's timing equipment? That place was notorious for showing trap speeds higher than vBox results. Just like Sacramento dragway who eventually re-calibrated to read lower. Maybe Ennis did the same thing but is now reading too low???


Brother I would invest in a vBox. That thing in conjunction with a logger is the best thing for figuring out what issue you are experiencing real time. For example this weekend at shift sector I was laying down 139-140mph 1/4 mile mph and 6-second flat 60-130's and then all of a sudden my vBox is showing 136 1/4 mile traps and 6.7 60-130's. So I then stopped racing looked at logs and it showed a massive spike in IATs. Figured my meth stopped flowing and there is otherwise no way to tell. Filled up the meth tank and then after a couple more runs viola the tank was still full so there was my issue. There's a lot of debate on the accuracy of the vBox but it has been instrumental for me in early-identifying problems and getting them rectified quickly in conjunction with logging.

 

+1
Idem

 

^
THis, which is why I bought mine about a year ago.. and also learning to read my logs allowed me to do the same..

I had a similar issue a few months back, 60-100 time was slower and boost seemed a little off.. checking the logs showed a decent delta between desired and actual boost.. Did a pressure test and found a small leak on the drivers side diverter valve..