Quickest DSM w/ Stock Exhaust

[slipstream808]

Thinking about it I guess with a larger exhaust there is a greater pressure differential between the gasses before the turbo and after the turbo and the gasses would naturally want to "crossover" and equalize faster putting more force on the turbine.

That's just my train of thought, though.

 

[1qkfwd]

This is a good discussion so don't mind my itch but. . .



This is just not true. A stock exhaust system CANNOT kill a big turbo. It will spool slower. This means it does less work. This also means that everything internal to the turbo doesn't see as much stress as with full 3" exhaust. . .




With my small 16g at stock boost, stock cams, and stock sidemount, I saw a significant increase going from a 3" exhaust (with simply a glasspack and a resonator tip) to an open o2 housing. So I lean to a stock exhaust as being restrictive even for stockish cars.

I would agree with that. I do see a downside of me running the stock exhaust though. Under full load conditions have a smaller diameter exhaust would hold back heat due to the backpressure. I can see this raising EGT's and eventually cracking the manifold or turbo housing.

 

[dsm-onster]

That I can see being possible. . .

 

[ApexVIII]

My friends bone stock 97 tsi awd minus a 16g at 10lbs went 13.0@104

When I say bone stock I mean EVERYTHING minus that 16g.

no way , my car at (ported b16g)12psi felt like a mid 14 sec car.

no way 10psi on a 16g will run a 13.0

 

[PIMking]

My friends bone stock 97 tsi awd minus a 16g at 10lbs went 13.0@104

When I say bone stock I mean EVERYTHING minus that 16g.

HAHAHA I call BS!!!

I had a 16g on 18psi and uicp bov full exhust including tubular manifold and ported o2 housing and I ran 14.00.

I want to see video.

Shoot my 91 has UICP BOV 16g 3' downpipe with a 3" test pipe to a 2 1/2" exhaust. Fresh .20 over motor with a ported and polished head with COMP cam 100200 cams with 750 cc injectors and DSMlink. I also have a stage 3 TRE tranny and act 2600 clutch with a fidanza lightweight flywheel. I was hoping to hit mid to low 12s on racing fuel.

 

[asd_gst]

yes i second that lets see a video or a time slip and i would like to see pics of this "stock" car

 

[dsm-onster]

well I ran a 13.5 with a FWD and stock intercooler and fuel with the stock 14b at the edge of fuel cut which for my car was about 15 psi. the 16g can do better at the same boost as the 14b because of the larger turbine housing, but 10psi does SEAM a little far fetched.

 

[asd_gst]

what was done to the car besides stock intercooler and fuel and turbo? slick? tranny? im just curious

 

[dsm-onster]

Stock fuel, but my fuel pump was rewired. But I had 225 tires. Street radials. Lot's of logging, lots of seat time, and a hacked 1g maf. No exhaust. I ran the exhaust cam retarded 1 tooth and it helped. Spool came in all at once so I could make better time shifting earler than 6500rpms. I swapped to a 7cm^2 turbine hosing from a blown 16g and hit fuel cut at 5K. That's how I know I was VERY close to fuel cut with my setup. The hacked maf helped lean her out a little plus it added some timing. I lost mph advancing base timing at the cas. If I had an safc, she could have done a little more, I guess. But, I never knew my a/f ratio because I wasn't logging a wideband.

I'll tell you this: dropping the exhaust helped tremendously through out the rpm range it widened my powerband.

 

[1qkfwd]

well I ran a 13.5 with a FWD and stock intercooler and fuel with the stock 14b at the edge of fuel cut which for my car was about 15 psi. the 16g can do better at the same boost as the 14b because of the larger turbine housing, but 10psi does SEAM a little far fetched.

What was your MPH on that run?

 

[asd_gst]

Stock fuel, but my fuel pump was rewired. But I had 225 tires. Street radials. Lot's of logging, lots of seat time, and a hacked 1g maf. No exhaust. I ran the exhaust cam retarded 1 tooth and it helped. Spool came in all at once so I could make better time shifting earler than 6500rpms. I swapped to a 7cm^2 turbine hosing from a blown 16g and hit fuel cut at 5K. That's how I know I was VERY close to fuel cut with my setup. The hacked maf helped lean her out a little plus it added some timing. I lost mph advancing base timing at the cas. If I had an safc, she could have done a little more, I guess. But, I never knew my a/f ratio because I wasn't logging a wideband.

I'll tell you this: dropping the exhaust helped tremendously through out the rpm range it widened my powerband.

stock downpipe still? i dropped my exhaust once just had stock downpipe open, but car was running bad due to knock sensor and o2 were bad, i think i might take it off again tonight

 

[dsm-onster]

101.54mph. No exhaust. No down pipe, nothing. Just o2 housing. The o2 housing outlet faces away from the alternator .

 

[asd_gst]

oh ok i see

 

[1qkfwd]

So I just got back from the track this weekend. i was on the hunt for 12's but I didn't get it. I am going to try and hit 12's with the stock downpipe back exhaust and all the stock intercooler pipes off a 1G. I will start off by saying this car needs a lot of work. The 4 bolt howls, I am running a 90 single syncro trans, and the engine compression goes from 75 to 115 on the high side. This is at a 4500ft elevation so the numbers are roughly 25-30psi per cylinder lower than most of what you guys see. So I managed a personal best time of a 13.3 @ 100.9 MPH with a 1.778 60ft time. I was having problems with boost all day and ould not get it right where I wanted. I was able to keep the trap speeds 100 mph after the 13.3 run but could only get a best of a 13.5 to back everything up. I am getting together a beter engine so the car should run a lot faster. I want this 12 sec time slip on most of majority of the stock mitsu parts no nitrous and 100 octane pump gas.

 

[talon187]

Im going for 11s...ive got a pte57 trim huge 02 hosuing full apexi exhaust twin disk clutch built trans ported 2g exhaust manifold with a tial 38mm on it and a full bushur race core with a tail bov and a eagle wesico motor with arp everything and mitsu 4 layer head gasket. and a custom intake manifold with a 75mm throttle body the head is totally stock. im running like 23ish psi on pump im using a maf pro im almost tempted to put a jdm intake manifold on and a stock throttle body but i dno think i could hit 11s? im alittle neverous on geting it out of the hole because i just broke a rear axle and replaced it dont want to do it again. i doubt i could find another one . stupid 3bolts

 

[1qkfwd]

You say that you have Apexi exhaust thats not what we are talking about here in this thread. I am talking about keeping the stock downpipe, cat, and catback exhaust.

 

[wancsta]

Well ide say your best bet would be to unbolt the downpipe and swing it to the side then you'll still be running your full stock exhaust otherwise I don't really see a point to this. You will probably just end up burning something up imho but to each their own

 

[JusMX141]

Here it is, a 12-second pass with the full stock exhaust:

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The stock downpipe was repaired where the OEM flex section broke out, but it was replaced with a section of 2.25" piping and a new flex....all are the same size as stock. The stock cat is in place and not gutted. The 1G 6-bolt has somewhere around 180k on it and has never been disassembled.

 

[dsm-onster]

There was a dump tube. Was the stock o2housing used? It's hard to see it in the video.

Reinserting the wastegated exhaust gases disrupts flow a LITTLE bit. Well a little more for a turbo that isn't being pushed hard. More gases are gated and disrupting the flow out the turbine wheel.

 

[ZenkaiRacerDsM]

Damn nice run on that stock exhaust. Is that an ebay wastagate?

 

[JusMX141]

Was the stock o2housing used? It's hard to see it in the video.

Stock 2G o2 housing- no portwork. Still has the sealing ring between the o2 housing and the downpipe.

The wastegate flapper was tacked shut on the turbine housing to allow the use of the external wastegate off the manifold. The 20G's turbine housing is ported and matches the inlet dimension of the SBR Stainless exhaust manifold.

Is that an ebay wastagate?

I believe it's a XS Power 38mm wastegate. I've seen these gates used on numerous DSM's- they've worked perfectly at controlling boost, and I have yet to personally see one fail due to a hole in the diaphragm or other mechanical malfunction. I wouldn't hesitiate to buy one.

 

[GRNDSM]

Congrats on a pretty quick car! But I am sorry guys, calling this a "stock exhaust" is just not right!

# 1 As you can hear from the video, the WG is wide open much of time! That means that certain percentage of exhaust gasses bi-passes the restrictive, stock exhaust!

#2 What is the point of "stock exhaust"? IMO, the biggest advantage is that you remain stealthy to cops. And clearly, this thing is anything but stealthy once you reach set boost.

To claim this a "stock exhaust car" you need to route the WG back into the exhaust! Otherwise, it is just a relatively quite (off boost), quick car.

 

[turboglenn]

I"d like to build a 3" DP to a 2.5' exhaust with a quiet (and surely restrictive muffler) then have a cutout at the DP so when i wanna show a vette where he stands I can just flip the switch.. Then the rest of the tim i can pass by cops without getting the punk kid eveil eye from them

I couldn't see stock exhaust though.. Kevin Drapen had a 60 trim t3/t4 on his wifes new style VW bug with a stock exhaust. And although it was quick, you could feel that a good exhaust with no cat would would really bring it to life. It's the model that started as a turbo in case you're wondering

 

[JusMX141]

#2 What is the point of “stock exhaust”? IMO, the biggest advantage is that you remain stealthy to cops. And clearly, this thing is anything but stealthy once you reach set boost.

To claim this a “stock exhaust car” you need to route the WG back into the exhaust! Otherwise, it is just a relatively quite (off boost), quick car.

I spoke to the owner earlier and he said for the upcoming season he'll gladly reroute the wastegate into the downpipe to quiet all the naysayers. I don't expect the timeslips will suffer one bit from the wastegate gases that are bypassing the turbine housing through a 1/4" gap being rerouted. It was previously dumped because it was simpler to fab than a reroute pipe.

There was no point to this project other than to see if it could be done.