Silverback

Those of you with a turbo setup, how fast have you gone or how much horsepower have you made with how small a down pipe? I want to hear from those of you that are running singles with 3 or 3.5” down pipes (<4”), and maybe some dual setups with <2.5” down pipes? A brief description of the setup would help keep the answers in context.

To give you some idea of why I’m asking, I originally set out to find a body/shell to build a turbo project in that I pretty much had all the running gear for, wanting to build a “race car” that could see some street time. What I ended up finding/getting a good deal on was a TA that was lot more complete than I hoped for, it even has working air conditioning and cruise control, it’s actually a really nice driver. So I’m thinking more like “Ok, street car that is going to see a lot of race time…” Looking at it, I think I can see how to wedge everything in it but I’m just not sure about the down pipe. 3” looks tight, and it looks like it would take a minor miracle to fit a 3.5”

Silverback

So no one has run fast/made a good deal of power with a turbo setup using a 3" or 3.5" down pipe?

RW99

I have the PT* kit with a T67; I'm pretty sure this is a 3" downpipe. It's a very tight fit. Numbers in sig.

Beaflag VonRathburg

iTrader: (176)

You can go really fast on a small downpipe. Jose at forced inductions went low 10s or so I think with a 3 inch downpipe in the 1997 SS on their site. I'll be running a 4 incher once I get mine finished. I'm guessing this is a third gen car?

engineermike

9.9 at 146 mph on a single 3" downpipe at 17 psi. I'm pretty sure there's more in it too.

Mike

Silverback

Well, the current car in question is an 87 TA, why, what made you guess that?

Engineermike, I’m pretty sure that your combination was one of the ones that I was thinking about, but I might be mixing it up with someone else, I thought that you measured some excessive hot side pressures, E/I pressure ratio and were going to go with something bigger. What hot side are you running on that 76 and what headers/manifolds are you using?

engineermike

I'm running a 3" log-style manifold feeding a .96 AR T76GTS. 3" downpipe to a 3.5" exhaust system with a Magnaflow muffler. At 17 psi boost the exhaust pressure is 34 psi. I had numbers as high as 48 psi at the same boost with an Aerochamber muffler and smaller intercooler (yes, it matters). I think it would benefit from a 3.5" downpipe, but it would be a real challenge to fit it.

Mike

Silverback

hum... what size intercooler did you have and what did you go to (suddenly becomming a pertinent question since I'm rethinking all that to work with AC)?

engineermike

I was running a vortech aftercooler that had over 2 psi drop across it. Now, I'm running a custom Bell unit that's 2.5 times the size of the Vortech unit and the pressure drop is <1 psi.

Mike