jgkurz Posted October 29, 2004 Share Posted October 29, 2004 Hi all and Scottie-GNZ, For those of you running the famous "Scottie downpipe" please chime in. For those of you who are wondering what I'm talking about, I have a custom turbo downpipe on my Z made by Scottie-GNZ several years ago. I believe he made several for folks who may hang out on this list. It is a quality unit and has served my well. Here's a picture: http://pg.photos.yahoo.com/ph/jgkurz/detail?.dir=583a&.dnm=c19e.jpg&.src=ph The pipe is 2.5 inches which may be limiting my HP potential. I have 3 inch mandrel bent exhaust so having the smaller downpipe changed out to a larger size may give me a couple ponies. Does anyone have experience making near or over 400RWHP with this downpipe? So far with an extremely rich 10:1 mixture I've made 360RWHP and 424RWTQ with the 2.5 inch pipe. Quote Link to comment Share on other sites More sharing options...
pallnet Posted October 29, 2004 Share Posted October 29, 2004 I have one on my car at the moment. I just got her running and somewhat tuned about a week and a half ago just to find that the stock turbo clutch setup will not hold the torque at all. So she is sitting and waiting on clutch parts to arrive. I have 2.5" exhaust all the way back and when I goto 3"(very soon, 2.5" was what I had on the car already) I will upgrade the DP as well. You are right though. It's a VERY NICE pce of work. The quality is top shelf... I do not know it's limits yet. A tool you might want to look into getting is the LM1 wideband O2 setup. I have one and it's awsome. That's if you don't have one already. Quote Link to comment Share on other sites More sharing options...
z-REX Posted October 29, 2004 Share Posted October 29, 2004 when either of you gentlemen choose to upgrade, let me know... i can think of a turbo 240 that would LOVE one of those! Quote Link to comment Share on other sites More sharing options...
GrayZee Posted October 29, 2004 Share Posted October 29, 2004 I can't comment on the limit of horsepower you can get with that DP (although I'm sure it's pretty high) However if you think you need something better I can tell you that it is possible to get a 3" DP with two 45degree bends to fit in a early Z. The outlet flange on the turbo is only 2.5 but mine has a cone that flares out to 3" before the first bend. When I first got my turbo engine running I had a 2.5" DP with mandrel bends but the rest of the exhaust was crush bent with a plain old run of the mill muffler. It was a completly stock turbo engine and boosted to 7psi. Last spring I got a complete 3" mandrel exhaust with flow through muffler and the difference was AWESOME! Now there is pretty much no lag at all and it runs 9psi and I've never messed with the wastegate. here is a pic: http://members.shaw.ca/icecube/DPclose.jpg Also if anyone is interested to know, I gave my old DP to a buddy with a turbo 240 with a borg-warner transmission. We were able to figure out that it is possible to have a 2.5" DP like Scotties even with a B/W tranny. All we had to do is grind a bit of one of the aluminum "fins" on the side of the tranny. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted October 29, 2004 Share Posted October 29, 2004 That DP was designed specifically for the stock T3 and T3/T04 hybrids. With the T3 wastegate having a 2 1/8" id outlet I never gave much thought to exceeding the HP limit you are at now. You have to wonder if a larger diameter pipe would help but you also have to look at how much HP is being extracted from a 3" pipe and wonder if the 2.5" limit has been reached. The most HP I personally know of is a buddy here who ran a 240Z with a j/y L28ET, hybrid turbo, SDS, Spearco and with 22psi on street tires the car went 11.7 @ 119. That factors out to 337RWHP but since that is derived from a 1/4-mile and not peak like on a dyno, we were estimating it would closer to 350+ on a dyno. Based on how the car ran we never gave any thought to the DP being a restriction. I am at 520RWHP based on my 1/4-mile (how much on a dyno???) and plan sometime in the future to up that about 10% and going bigger than the 3" I now run is not even a consideration. If you are just looking for a couple more HP, I say instead of spending $$$ for a 3" mandrel SS DP, do some more tuning to get the A/F from 10.0:1 to around 11.2. You might be amazed what that will gain and of course cost you nothing. I say take it out and spend a couple of $$$ to polish it to a miror finish :D j/k. OTOH, go for it if just must have it. Nothing worse than having a nagging feeling that something isnot right. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted October 29, 2004 Author Share Posted October 29, 2004 Nothing worse than having a nagging feeling that something isnot right. I don't have that "nagging" feeling yet, but I would like to make an honest 400 RWHP without changing the downpipe. The AFR's definitely need work so I should pickup some power on my next dyno run. At 360HP I was running about 18psi so correcting the AFR and running a bit higher boost might get me to my goal. Thanks everyone for your comments. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.