put in a DP and seems the car has lost power???

[1985GN]

hey guys i just installed a Mease DP and test pipe. when i took the car for a ride with the same 20psi and same mods as my sig it feels slower. the car used to spin the bald Drag radials now it seemed to not be able to now. i had the stock DP with stock Gutted Cat and all i did was swap in the DP and test pipe. why could this feel like that?? i can feel the difference just from getting on it. what could i look for?

 

[GN ERGY]

Could you still build boost? I was thinking that maybe the puck wasn't sealing off the wastegate hole on the turbo. I know when I put a bigger exhaust elbow in my turbo it wouldn't seal, it was getting caught at an angle, had to shim the back of the puck. Just a thought. Good luck.
Tarey D.

 

[1985GN]

yeah boost builds up nice and quick and right to 20psi where i have it set. my exhaust note seems to have changed too is this common with a DP? thanks again im gonna go make some passes with the car.

 

[national]

I had the same problem when I installed a THDP !!
It did slow me down at the track also..lost it in the 60ft...my opinion is the big DP is like installing a big cam..it may work better with alot of other parts but isnt a very good investment..if I had it all over again to do..I wouldnt have bought it..THDP claims big increases..like 2-4 tenths in the 1/4..I dont see it & would demonstrate it on my car to prove it..most people that say it rocks..never races it to prove it & after they spend all the money..its hard to admit you got taken...oh well..JMO..hope this helps
Brian

 

[blackbuick87]

I dont have a Mease but it should have quicker spool and maybe a hair more top end. When I put mt 3" on it also made the exhaust sound a little deeper.

You could possibly be running a little leaner now due to the increased airflow capability your engine has now. Try adding a # or two of FP to see if it pulls better

 

[tangofox]

I just put the same 3" Dp on my car and I did pick up 3 tenths in the 1/4. That was actual track measurements. I did have to bump up the fp a # or two since it ran a little leaner. I too had the stock pipe with gutted cat.

 

[Brooks]

For those of you that lost ET/MPH after installing the downpipe. It's possible you're running a little leaner now.

I installed a THDP a couple weeks ago on a mostly stock car with the same results and had to tweak the fueling in my chip. Afterwards there was a significant improvement.

If you can burn your won chips try adding a little fuel. If not, try upping your fuel pressure and see if that makes a difference. If it does, find somebody to burn a modified chip for you.

Good luck.

Charles Brooks

 

[national]

Well i hope 85gn has luck with it..im not a guru on these but consider myself pretty good..i ask & post on here sometimes to make double sure of my actions...When i replaced my downpipe..it was on a different but very similar night..even that i never ran any faster at any point & time..cooler..hotter..less humidity & all with different fuel pressure settings & all than i did with my stock pipe..ive checked it all too..dp is sealing perfect on it..ill tell ya what it did kill on me was my 60 ft..mph might have been the same..but my 60 before the pipe was 1.68..never had better than a 1.78 mostly 1.80's after..even now after inj..downpipe..turbo..front mount..i still havent had a 60 ft in the 1.60's..mostly 1.80's with several 1.70's..my car has run a best of 7.62@92.5 so i know it runs pretty decent for what it is..theres more E.T. in that mph i know..if my 60 ft was where it should be i know it would be in the high 7.40's...when i was all stock but a chip i ran a 7.92..then spent all this money to go 3 tenths faster & so far the front mount was the biggest improvment of them all..after turbo & injectors were put on the car ran almost the same #'s with maybe a .05-.07 increase overall but the DP was my worst so far..I went from 7.92 to like 8.20's..tried different name chips & never did any better..well enough on that..im not slammin the THDP pipe but just stating my experience...good luck to all
Brian
Brian

 

[UNGN]

I did back to back testing of a THDP and a ported elbow/2.5" stock replacement downpipe. I did 5 runs each with the conditions identical. All runs were between 11.74 and 11.95, I threw out the worst two runs of each and averaged the remaining 3.

I found the the THDP only to be quicker by .05 seconds and 1.5 mph than a stock elbow/downpipe. .05 isn't much. If a car isn't consistant, that could easily get lost in other variables. If a car runs slower than this, the actual difference should be less. The THDP does appear to allow slightly more top end power above 5000 RPM given the increased trap mph.

FWIW, I picked up 4 mph when I initially bolted on my THDP and opened the dump (when the car was running mid/high 12's). That wasn't because the THDP was so much better than my stock elbow, but it was because my exhaust was so bad, opening the dump freed up a ton of HP.

 

[TurboJim]

Going from 2.5 to 3" when you dont need or have the flow may have slowed exhaust velocity enough to hurt power at lower RPM's.

Just as header primaries/collectors should be tuned to a car, in our case I'd think a DP should be part of the equation.