Quickest DSM w/ Stock Exhaust

[jusmx141]

Just wondering if anyone out there has ever tried pushing the stock exhaust to it's limit. I'm not talking about cutouts, or OEM downpipes and cats with a 3" catback.....I'm talking FULL stock exhaust.

I have a buddy who's currently trying to make it into the 12's with a full stock exhaust. His best time so far is around a 13.2 @ 105.xx; the car is a 1995 TSi AWD- 6-bolt swap, TD05H 20G, Tial 38mm gate on the manifold, FMIC, fully modded fuel system, tuning with DSMLink.

You wouldn't believe how laggy the car feels with the 20G feeding into the stock exhaust....and you can imagine the surprise when the wastegate opens

[RedTurboEclipse]

I'm running an MHI big16g with absolutely full stock exhaust system. stock manifold, o2, turboback. no porting whatsoever, except on the turbo. stock smic, just the usual others (filter, pipes, bov). I see 20lbs full boost at 3300-3400. Still pretty quick spool surprisingly enough. And the car definitely feels fast. I however, don't want to start doing launches with the stock clutch setup.

[rhamlinii]

Originally Posted by jusmx141

Just wondering if anyone out there has ever tried pushing the stock exhaust to it's limit. I'm not talking about cutouts, or OEM downpipes and cats with a 3" catback.....I'm talking FULL stock exhaust.

I have a buddy who's currently trying to make it into the 12's with a full stock exhaust. His best time so far is around a 13.2 @ 105.xx; the car is a 1995 TSi AWD- 6-bolt swap, TD05H 20G, Tial 38mm gate on the manifold, FMIC, fully modded fuel system, tuning with DSMLink.

You wouldn't believe how laggy the car feels with the 20G feeding into the stock exhaust....and you can imagine the surprise when the wastegate opens

This is a bad thing your trying here. Making a capable 10-11 second turbo and running 13's with it makes no sence at all. He put all that money into parts, and many other have been 12s with no tuning, act 2100, boost contoller, and a stock 14b. Please dont forget the 3 inch exhaust sustem. Why dont he put an exhaust on the car, and try for atleast 11s. He did trap higher then I did whan I ran 12.83 with the ablove mods on a stock 6 bolt awd car. i was at 104 and some change. I've been 13.50s in an almost stock 1990 fwd eclipse. A boost controller an afc were the only modification in the car. On stock street 205/55R16 all seaon tires, I had a 2.0 60ft that pass and trapped 105.

[GRNDSM]

I hate to point out the obvious, but having an external dump WG defeats the purpose of having "full stock exhaust" because IT ISN'T...

Think about it, he is bi-passing the exhaust, thus require less exhaust to flow thru the restrictive, stock exhaust!

[need2boostpsi]

Originally Posted by GRNDSM

I hate to point out the obvious, but having an external dump WG defeats the purpose of having "full stock exhaust" because IT ISN'T...

Think about it, he is bi-passing the exhaust, thus require less exhaust to flow thru the restrictive, stock exhaust!

bingo! think of all the exhaust gas that is being bypassed is being dumped before the restrictive exhaust.

[rogergoochman]

it could be recirculated guys. He didnt say though.

[GRNDSM]

I highly doubt it, who would spend considerable effort to tap back into a stock downpipe? And recirulated WG does not sound louder when it opens.

Anyway, back to the original question. Back in the late 90's I had to put stock exhaust on my Green Machine to pass emissions (so this was with a stock cat). Since it was on the car, I decided to take it to the track, just for fun.

As I recall, I ran low 13’s, which was exactly 1 second slower than what I was running at the time on the Buschur 3” exhaust. Back then the car was running low 12's , in “Stock Appearing” trim (VPC, 16G turbo and sidemount i/c).

I beleive that with good tuning, high 12's is definitely possible. Plus, others have run mid 12's with stock exhaust and a test pipe.

[ARFWD]

I am running a stock full turbo back exhaust. I will get my car into the 12's with the stock exhaust and intercooler system. The first time I took the car to the track I ran a 13.8 @ 90 MPH. This was on full stock fuel system and 16LBS and 110 octane gas. I am waiting for my engine rebuild cause the engine in this car sits with compression around 115-75-95-110. I am on more boost now and the stock MAS is not over ran anymore (13.8 run hz falling off the charts) so I should be getting close. I may take it to the track one more time before the weather starts getting bad just to see where it is at.

[lasthope05]

A buddy of mines ran a mid 11s on a full stock exhaust. Only thing was the extra back pressure there blew up his turbo.

[BoostFrenzy]

Originally Posted by lasthope05

A buddy of mines ran a mid 11s on a full stock exhaust. Only thing was the extra back pressure there blew up his turbo.

EXACTLY what I was going to say!! Back Pressure is bad people. If you are going to run a bigger turbo that FLOWS more, upgrade to a bigger exhaust that FLOWS more. Too much pressure is going to cause it to fail.

[MidShipCivic]

I've never ever heard ''back pressure'' blowing up a turbocharger. A turbocharger generates back pressure and you won't make any efficient power unless you have higher inlet pressure (T1) vs outlet pressure (after turbine wheel) (T2).

[JayRolla]

High flow exhuast lets a lot of hot gases get out the motor faster. Why run lots of boost and keep all the heat in the motor. This just sounds like a dumb idea to me.

[spyderturbo007]

I was pushing about 34lbs/min on the stock cat back running a 2.5" DP and high flow cat. After installing a ported manifold, ported O2 sensor housing and a 3" cat back, I saw no increase in flow. So, at 34lbs/min, the stock catback isn't a restriction. That was at 20psi.

I know that isn't a full stock exhaust, but I thought I would throw it out there anyway.

[jusmx141]

Originally Posted by GRNDSM

I hate to point out the obvious, but having an external dump WG defeats the purpose of having "full stock exhaust" because IT ISN'T...

Think about it, he is bi-passing the exhaust, thus require less exhaust to flow thru the restrictive, stock exhaust!

I thought about it....and I didn't believe that a 38mm wastegate opening 1/8" to 1/4" allowing boost from runner #1 to be dumped to the ground through an 1-1/4" pipe could really add much in the way of performance.

I could understand if an electronic exhaust cutout was wired to open up once the engine reached full boost.

[Hideki]

I just don't know why you'd want to do this, but then again I'm just an ignorant tuner

[spyderturbo007]

I hung onto the stock exhaust for so long because I hate loud, obnoxious exhausts. I wanted to keep my car as quiet as possible, but I finally gave in and upgraded. Well, I wouldn't call it an upgrade in my case, but maybe if you're pushing 40+lbs/min.

[daren_p]

Originally Posted by spyderturbo007

I was pushing about 34lbs/min on the stock cat back running a 2.5" DP and high flow cat. After installing a ported manifold, ported O2 sensor housing and a 3" cat back, I saw no increase in flow. So, at 34lbs/min, the stock catback isn't a restriction. That was at 20psi.

I know that isn't a full stock exhaust, but I thought I would throw it out there anyway.

Hmm thats interesting, I use to run the Apexi N1 system which is basically a 3" system, except I found out it probably necks down to about 2" inside the resonator. When I switched to a complete 3" system from the cat back (always ran the 3" HF CAT), I gained 4 lb/min or slightly more with no other changes. This was origionally making around the 40-41 lb/min range & then after in the 45 lb/min range, once I reduced the boost to make things equal (as the exhaust also added about 2 psi to my origional boost setting).

[spyderturbo007]

Maybe we are beginning to dial in the airflow at which the stock exhaust becomes a restriction. My cat back is the Greddy EVO 2, which is pretty much 3" all the way back to a disgusting 37" tip on the back.

So you were at 40lbs/min and saw an increase, whereas I was at 34lbs/min and saw no increase. Anyone around here at 36 - 38lbs/min that happened to do what Daren and I did?

Then again, I'm still running the SMIC, so that could be causing the restriction, but I doubt it. From what I've seen, for my boost pressure, the airflow is normal. Also, everytime I've turned up the boost, I've seen a proportional increase in airflow. So at this point, I'm not thinking the SMIC is a flow restriction.

[daren_p]

Originally Posted by spyderturbo007

Maybe we are beginning to dial in the airflow at which the stock exhaust becomes a restriction. My cat back is the Greddy EVO 2, which is pretty much 3" all the way back to a disgusting 37" tip on the back.

So you were at 40lbs/min and saw an increase, whereas I was at 34lbs/min and saw no increase. Anyone around here at 36 - 38lbs/min that happened to do what Daren and I did?

Then again, I'm still running the SMIC, so that could be causing the restriction, but I doubt it. From what I've seen, for my boost pressure, the airflow is normal. Also, everytime I've turned up the boost, I've seen a proportional increase in airflow. So at this point, I'm not thinking the SMIC is a flow restriction.

Yes was at 40-41 lb/min before & doing multiple other logs on the exact same stretch of road & when I reduced my incresed boost after the new system to match exactly my origional boost (AVC-R 4 bar logged via DSMLink), my airflow was up to the 45 lb/min range. The outside air conditions were very similar, actually the air was abit cooler with my old system logs, so they should in theory read abit higher. I will also add the new system looks 100% stock

Your airflow does seem to be inline with that setup but would be interesting to know if Greddy uses these extremely necked down internally resonators, like Apexi? I would imagine this is strictly for sound control (Apexi N1 was very quiet on my setup)

I'm also running cams, an evoIII intake mani & the nice flowing FMIC so this may come into play as well, about where the actual restriction is. Yes, your airflow should basically always increase in relation to boost but that defently doesn't mean you don't have some restrictions. I would bet your stock SMIC is posing some restriction, as when I swapped from my SMIC to a FMIC I still had stock cams & intake mani & I saw atleast a 2lb/min increase, running the same boost. This was also vs a HRC SMIC which should flow much better then the stocker, so your results could be even greater .

Your doing headstuds anyways, might as well add a short route FMIC to the shopping list