exhaust size?

Quote:

Originally posted by GLHNSLHT2 Nope, you weld the 2.5" donut and pipe into the JRB style 3" d'pipe. The Flange I was referring too is the stamped piece of steel that holds the downpipe to the SV.

I see, must have not read your whole post. I read it now and see what you are saying. Wouldn't welding the big flange on be a good idea too? Is there a welder that can weld cast iron?

[GLHNSLHT2]

Quote:

Originally posted by 87DTNA I see, must have not read your whole post. I read it now and see what you are saying. Wouldn't welding the big flange on be a good idea too? Is there a welder that can weld cast iron?

By the time you find a welder, flanges, and pay for it all it'd be easier to just upgrade to a full 2.5" or 3" SV. The thing with going up sizes also is that the whole SV itself is larger internally too, not just the hole.

[GLHNSLHT2]

Quote:

Originally posted by 87DTNA Oh I must have not understood what you were trying to say then. I thought you were taking the large flange off a mitsu SV and welding it onto a garret 2.25'' SV. I know that they do not interchange, garret has 5 bolts mitsu has 4. Plus the garrets wastegate flapper is on the SV, the mitsu has the flapper in the turbine housing.

Nope, you weld the 2.5" donut and pipe into the JRB style 3" d'pipe. The Flange I was referring too is the stamped piece of steel that holds the downpipe to the SV.

[WantSum?]

alrighty i think i have it under control now. i just wish the SC had a t2 in it so i could actually do some work to the motor with out performing heart surgery. I think i just may leave it stock for now then decide what im going to do over my summer break from college. Using the T1 with the tranny thats in it the car will never be nearly as fast i want it to be. I am a bit of a speed freak ( been racing proffessionaly since i was 5) I think i just make keep it stock or close to it and find a T2 or 3 down the road to make into some thing that will get outta its own way. Thanks for all the help guys, i think i might switch the SV out and go that route for alittle gain.

nate

[GLHNSLHT2]

The car is light. With a T2 conversion which is just the intake, turbo, and electronics and add an intercooler, port the exhaust manifold add 3" exhaust, you should have a mid-low 13 second car on street tires with your current motor and tranny at about 15psi. That's pretty quick since the car runs mid-high 15's stock. That should keep you satisfied enough till you can get a commonblock and a better tranny setup

With the lightweight rods you just need to keep the boost around 14-15psi. And No powershifting or peg leg burnouts with the tranny. Other than that things should be fine.

[Pat]

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Originally posted by GLHNSLHT2 I went from 2.5" straight pipe, to 3" with a dynomax Race mag. Pipe lengths stayed the same. The 2.5" was much louder. I am now running 3" straight pipe in the same configuration as the other two. I find it the same volume as the 3" with the dynomax. At idle I can't tell if it's running sometimes. Just a nice deep burble. The 2.5" was like a gun going off all the time. I didn't like it all the time it was too loud and sharp. Also I picked up a good amount of low end grunt going to 3". With the 2.5" I could go from about 10MPH in 2nd and floor it. The tires would be right at their breaking loose point but not cross it. Going to the 3" crossed that point by a big margin. Doing that would result in lots of wheelspin The 1st two systems (2.5" and 1st generation of 3") were with the .48 stock 87 T2 turbo. Going to the 3" was definately worth it and netted a gain in performance. If you have a garrett "Get Real" Get 3" from the beginning. Why spend the cash twice? I believe in the Do it once, do it right philosophy. Plan for future mods. It ALWAYS saves money in the long run. I know someone that had a 3" SV and 3" side exit on a T1 GLH with just a grainger. The Car absolutely screamed for what it had into it. 2.5" exhaust should of (and most of the system was) stock for our cars. 3" is just the next step up. Remember the little tiny sections of 2" and 1 7/8" pipe were from N/A versions of our cars. SAD! But Mopar had to save money somewhere. Now People see me with the oddball stock 2.5 in a 3120lb car that runs 13.8's@101.8 on street tires (2.360ft) and 13.5psi with 5700rpm shift points. So your results may very.

Of course the 3" was quieter, you were not running a muffler on the 2.5"!!!

Based on my track numbers, I've found that a 2.5" will do just fine for quite a while for most people. In the GLHS, I went 12.59 @ 110 with a 2.5" system through a 2.25" swingvalve on a stock garrett. Made some changes and went 12.53 @ 110 through the same exhaust at the same boost but with a 2.5" swingvalve. With both set ups, the car was trapping 110-111 mph consistently. Going to a 3" mandrel bent system and the car still went the same 110-111 mph. The .48 exhaust housing was definitely the cork. My R/T showed similiar results with the stock turbo. Through a 2.5" mandrel bent system, the car went 109-110 mph. Going with an open downpipe, the car still went 109-110 mph. Both cars were basically maxxing out the stock turbos.

If either car had a .63 exhaust housing, I'm sure that the 3" system would be the ticket and that gains would be seen, but the 2.5 does pretty darn well and until you're knocking on the door of 300 hp, it's probalby just fine. Hell, based on race weight, the R/T was putting more than 300 to the wheels through a 2.5" exhaust! In my opinion, until you're nearing or have passed that point, a 2.5 will do just fine.

[GLHNSLHT2]

Quote:

Originally posted by Pat Of course the 3" was quieter, you were not running a muffler on the 2.5"!!! Based on my track numbers, I've found that a 2.5" will do just fine for quite a while for most people. In the GLHS, I went 12.59 @ 110 with a 2.5" system through a 2.25" swingvalve on a stock garrett. Made some changes and went 12.53 @ 110 through the same exhaust at the same boost but with a 2.5" swingvalve. With both set ups, the car was trapping 110-111 mph consistently. Going to a 3" mandrel bent system and the car still went the same 110-111 mph. The .48 exhaust housing was definitely the cork. My R/T showed similiar results with the stock turbo. Through a 2.5" mandrel bent system, the car went 109-110 mph. Going with an open downpipe, the car still went 109-110 mph. Both cars were basically maxxing out the stock turbos. If either car had a .63 exhaust housing, I'm sure that the 3" system would be the ticket and that gains would be seen, but the 2.5 does pretty darn well and until you're knocking on the door of 300 hp, it's probalby just fine. Hell, based on race weight, the R/T was putting more than 300 to the wheels through a 2.5" exhaust! In my opinion, until you're nearing or have passed that point, a 2.5 will do just fine.

On the 1st 3" I was running a dynomax bullet which is just straight through. If you read down a bit further you see I've taken that out of the system and the car is still no where as loud as it was with the 3" Just a nice deep burble all the time. The 2.5 was deafening even at cruise.

The boost came on sooner, harder, and gave me more under the curve hp and torque witnessed by me know being able to roast the tires from a 2nd gear roll. A noticeable gain in my book. Upgrading from that 1st 3" system to one with a 3" donut instead of the 2.5 and taking out the muffler (I don't think the muffler hurt flow too much hehe) I also noticed a gain which was 1-2" more vacuum at cruise, and at throttle settings that gave me 0psi before were now giving 5psi of boost.

Can you give us some more specs on your cars?? Boost levels? Mods? weight? 60ft times? Auto? Manual? Just curious.

I think these cars are alot like real estate. Except instead of Location Location Location, it's Exhaust Exhaust, Exhaust.

Also, like I said earlier if you're gonna do something like exhaust do it once. It's not like 3" is gonna hurt the motor or driveability of the car. If it's too loud add a cat, muffler or two of them. My 3" is no louder than an SRT.

[Pat]

Quote:

Originally posted by GLHNSLHT2 Can you give us some more specs on your cars?? Boost levels? Mods? weight? 60ft times? Auto? Manual? Just curious.

GLHS - Bone stock 2.2 T-II, stock garrett with 2.25" swingvalve dual core cooler, +20's w/5th injector, 2.5" exhaust, 18-19 psi, but of race gas 12.59 @ 110.8, ST was around a 1.90. Did make some 111 mph passes.

Changed to the top end to an '85 G head that I cleaned up the runners a bit, ported exhaust manifold and matched upper/lower half of 2 pc intake, same turbo with 2.5" swingvalve, +40's with RRR, pump gas, 18-19 psi, 12.53 @ 110.3, ST was about the same 1.90. Did make some 111 mph passes.

Same set up with 3" exhaust and S60 turbo/.48 exhaust housing w/clipped wheel, same boost netted 12.5x @ 110. Turning the boost up further resulted in very little gain, best was 12.45 @ 111 with a 1.8x ST.

GLHS was not lightened at all, so with me in it, I'm guessing a race weight around 2600 lbs. Passes were all around 18-19 psi. Going higher on the boost did not make me any faster.

Common denominator in all GLHS runs..... .48 exhaust housing.


R/T - Stock rebuilt bottom end, back cut valves, ported exhaust manifold, 2.5" exhaust, dual core cooler, +20's, stock 568. Ran 12.67 @ 109.4 with a 1.86 ST. Later the same day, ran on an open downpipe and ended up running 12.44 @ 110.3 with a 1.76 ST, 12.48 @ 109.5 w. a 1.74 ST and 12.48 @ 109.8 w/a 1.77 ST.
ET's were better, but I tried a new launch technique which resulted in much better ST's. The 60 ft times make up the ET differences. MPH pick up was next to nothing.

R/T also has no lightening done at all, so based on Larry and Wallace's weights, I'm guessing it was about 3350 or so with me in it. Boost that day at it's peak would run to 20 and very quickly drop to 16.

I'm definitely not saying not to get a 3" system put on the car. It definitely will flow better than a 2.5", but with all else being equal (pipe lenghts, mufflers, cat's, etc), a 2.5" is definitely going to be quieter and will flow more than enough for a car making under 300 hp. If you're seeing some gains, that's great, but from what I've seen based on my track numbers, there's little gain to be had with a stock turbo. IF noise is a concern and you don't think that you're going to be going for a low 12 second car, 2.5" works fine. If you don't mind the noise and/or you think you're going to really go for it down the road, definitely go 3".