3"downpipe

[pwhite]

My muffler shop quoted me a price of 150 to make and install a 3"downpipe from the turbo .My question is is their that much diff between his and a premade one from a vendor such as postons.

 

[c&cgn]

There isn't that much to be gained from a 3" DP if it does not eliminate the stock elbow. The elbow is where most of the restriction is. IMO you are better off with a THDP in that case. I found that a 3"DP doesn't make that much difference on a stock setup, but sure helps alot when you ahave a bigger turbo.

 

[d0n_3d]

mmmm actually i switched from a stock downpipe to a 3" downpipe with the stock elbow and that completely woke my car up...turbo spools like nothing now and i can boost 20 lbs easy if i want to...plus the sound of the turbo whistling louder is priceless

 

[UNGN]

I posted a wanted add in the parts wanted section for an ATR SS 2.5" downpipe and test pipe. I bought one for $110 shipped. No need for a muffler shop, it bolts on in about 1/2 hour to the stock elbow. SS lasts forever and a lot of people have switched to THDP style Downpipes so there are a lot of these gathering dust out there.

With a turbomike ported elbow (I needed a slightly bigger puck for my TA49) I did back to back testing between a THDP and the stock elbow, stock replacement 2.5" DP at BOP@B 2001. Here is the results:

Ported elbow/2.5" ATR downpipe/testpipe:

11.840 @ 113.08
11.859 @ 114.66
11.836 @ 114.72

Average:

11.845 @ 114.15 (avg 60 ft 1.680)


Terry houston 3" DP/Capped dump pipe:

11.745 @ 115.36
11.788 @ 116.05
11.838 @ 115.62

Average:

11.790 @ 115.67 (avg 60 ft 1.687)

Difference = .055 seconds and 1.52 mph

The results surprised me. I thought the THDP would be worth more. These weren't even all the runs. If I factored in the others (made it an avg of 5 runs each) the stock elbow ET would be a little closer (though the mph would stay about the same).

You can't knock a 1.5 mph increase, but it appears to help the top end charge more than the ET. The rest of the combo is stock driveline, stock intercooler with a neck, bluetops, TA49, 275/60 BFG's weather was in the mid 60's, track elevation 1400 ft or so. Your results may vary.

Based on this I would make the following recommendations:

1. Port your stock elbow
2. Don't have a muffler shop make a downpipe for you.
3. Look for a good used, vendor made SS downpipe (2.5" is fine)
4. Make sure you have a good exhaust system after the Downpipe (2.5" duals with straight thru performance mufflers, minimum)

 

[WarpSpeed]

Wow! I'd expect more of a difference too. I'd bet a dozen dunkin donuts, you'd gain that mile per or so with a 3" DP instead of that 2 1/2".

 

[Slo86GN]

Hmmmm, interesting info. I'm wondering what my 87 will do when I switch from the ported elbow/3" dp to my new Mease Eng 3" dp..... Think it'll pick up any without raising the boost....heheheh... Actually, I'll post the results once I switch them out for everyones info. Should be an interesting comparo, especially with the mods I have.

 

[UNGN]

A TE45 with a stock Elbow? I didn't even think they would mate up cleanly without the elbow walls having to be blended paper thin. Definately let us know what it runs with the Mease pipe. I would think you would pick up more than I did, with your set-up for higher rpm HP.

 

[Grumpy]

pwhite....is it a 3" mandrel bent?????

we run a crummy ported elbow on all my cars here with a 3" mandrel pipe...only gone 11.5s with it @ 118 in street trim..

oh this is with a Buick....everyone knows TTA's are even faster with this set up

 

[Slo86GN]

It mates up, but just barely. One thing I do hate is the slight exhaust leak between the elbow and dp. That's one reason I bought the ATR dp for the 86. I'm very anxious to see how much it picks up going from the ported elbow to the Mease dp....Don't get me wrong, the car pulls hard as heck now, but I'm getting antsy to see how much more is lurking in the combo.... It also might eliminate some errant knock that pops up now and then. It can do nothing but help with power and tuning.