jgkurz Posted September 21, 2007 Share Posted September 21, 2007 As some of you may know my car has been out of commission for a while due to some various upgrades. The major upgrade is a new downpipe and wastegate. Last summer, while on the dyno, I found that the car really was done making power after about 5200 rpm. The turbo I have was built for more than 371RWHP which is what the number I put down at the time. This coupled with some other symptoms lead me to believe I had a serious back pressure issue. It may be the turbo but I wanted to first start with the exhaust systems. My turbo is a custom job by Innovative so I don't know much about the compressor side. The turbine side is Nissan .63 with a stageV 10 blade wheel. Supposedly it'll support 500RWHP. The first DP in the picture is a stock L28ET unit. I never actually used it since Scottie-GNZ was making 2.5" mandrel bent DP's for a reasonable price. That is the 2nd DP in the picture and the one I made 371RWHP with. As I did more research I noticed that most everyone who had my setup was using a 3" DP. My original thought was that the 2.5" DP was fine but I now believe I was just asking too much of such a small pipe. BTW, my exhaust was 3" mandrel with one crush bend just under the diff. It's all 3" mandrel now. The 3rd pipe in the picture was purchased from another HybridZ'er. It's 3" but as I looked at it I felt I could make one better yet. I never ran #3. That brings us to the 4th. This is the one I just finished. I haven't started the car yet but I think it'll make a big improvement over the 2.5" DP. I tried hard to use long radius pipes and made sure the immediate exit from the turbo was a quick but with a smooth transition to 3". Lastly, I also wanted straight pipe out of the turbo instead of an immediate bend downward. I also wanted to get away from the internal wastegate. Luckily I found a flange on eBay that was made just for the Nissan turbine housing. I purchased some mandrel pipes and started cutting and welding. DP #4 is the end result. My ultimate goal is to get past that huge mountain of 400RWHP and to run an 11.99 in the 1/4 mile. All on gasoline, no NOS or water/methanol injection. All my other components support my goal but so far it has alluded me. Once I get the car back on the road I will be doing some AFR tuning then off to the drag strip and dyno to see if the new DP made a difference. Wish me luck. Quote Link to comment Share on other sites More sharing options...
Nigel Posted September 21, 2007 Share Posted September 21, 2007 Now that looks nice! Any interest in making more? I'd do it myself, but I doubt I'll ever have time... Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
slownrusty Posted September 21, 2007 Share Posted September 21, 2007 Wow very cool and a beautifully made DP (the last one). good read too...keep us posted on what your next dyno run brings in. Staying tuned. Yasin Quote Link to comment Share on other sites More sharing options...
jgkurz Posted September 21, 2007 Author Share Posted September 21, 2007 Now that looks nice! Any interest in making more? I'd do it myself, but I doubt I'll ever have time... Thanks Nigel. Since this unit took me all summer I think I'll pass on making more. I'm a capable fabricator, just really slowwwwww. Wow very cool and a beautifully made DP (the last one). good read too...keep us posted on what your next dyno run brings in. Staying tuned.Yasin I figured you meant the last one. . Thanks for the comments. Quote Link to comment Share on other sites More sharing options...
hughdogz Posted September 21, 2007 Share Posted September 21, 2007 Looking Good!! If the latest DP doesn't help get you to the 400 HP mark, I don't know what DP would Is that stainless material that is ceramachrome coated? Also, did you weld it all up yourself or did Hutchkins help out? Regardlesss, I really like the design and hope to build one of those soon myself. HorsepowerFreaks is having a dyno day tomorrow (Saturday) 3 pulls for $50. If you are going there, let me know because I definately want to check out your ride close up in person!! Quote Link to comment Share on other sites More sharing options...
jgkurz Posted September 21, 2007 Author Share Posted September 21, 2007 Looking Good!! If the latest DP doesn't help get you to the 400 HP mark, I don't know what DP would Is that stainless material that is ceramachrome coated? Also, did you weld it all or did Hutchkins help out? Regardlesss, I really like the design and hope to build one of those soon myself. HorsepowerFreaks is having a dyno day tomorrow (Saturday) 3 pulls for $50. If you are going there, let me know because I definately want to check out your ride close up in person!! Thanks Hugh. It's the Cermachrome which was done by RM Engineering. I'm a little worried about the coating if my EGT's get too high. My last DP had the same coating and had no trouble so we'll see. The welding was done by myself, my friend Bruce who has an awesome MIG setup and Hutchen's for the stuff I wanted TIG'd. Horsepower Freaks is a cool place but I prefer to spend time on a dyno where I can take my time analyzing data and adjusting parameters without a crowd of people watching over my shoulder. Maybe I'm bashful but it's what works best for me. I usually go to RRev Motorsports on Hayden Island. They have a DynoJet Model 224xLC with Eddy Current, wideband and boost reference. You are welcome to come over to the house if you'd like. I live in OC now. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted September 22, 2007 Share Posted September 22, 2007 Looks nice. I have done modded/tuned enough cars to know that you should make 400 whp with 2.5", though. Restrictive? Maybe a little but it shouldn't cork the engine; especially a 2.8L with a supposed 500 whp turbo that put down 374. Still very nice numbers. It's hard to tell, but if pipe #2 is an internally gated non-bellmouth pipe I am surprised you didn't have creep issues. Anyways you slice it, though, I think you have your downpipe sorted. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted September 22, 2007 Author Share Posted September 22, 2007 Looks nice. I have done modded/tuned enough cars to know that you should make 400 whp with 2.5", though. Restrictive? Maybe a little but it shouldn't cork the engine; especially a 2.8L with a supposed 500 whp turbo that put down 374. Still very nice numbers. It's hard to tell, but if pipe #2 is an internally gated non-bellmouth pipe I am surprised you didn't have creep issues. Anyways you slice it, though, I think you have your downpipe sorted. I also thought my 2.5" DP would have supported 400RWHP. I tried for a long time to find HP in other parts of my setup. I just couldn't get there. Yes it did have the factory internal wastegate. I did modify the turbo outlet to 2.25" and ported the wastegate. However, boost creep was never the issue. Strangely, boost would always bleed off as RPM and HP went up. This symptom still occurred even with an extraordinarily strong spring in my custom wastegate actuator. Finally I attributed the boost bleed to backpressure pushing the internal wastegate flapper open. The 2.5" DP may have gotten me to 400RWHP if I could just keep the wastegate from blowing open. Like you inferred, my new larger DP with the Tial wastegate should cure some or all of my problems. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted September 22, 2007 Share Posted September 22, 2007 I also thought my 2.5" DP would have supported 400RWHP. I tried for a long time to find HP in other parts of my setup. I just couldn't get there. Yes it did have the factory internal wastegate. I did modify the turbo outlet to 2.25" and ported the wastegate. However, boost creep was never the issue. Strangely, boost would always bleed off as RPM and HP went up. This symptom still occurred even with an extraordinarily strong spring in my custom wastegate actuator. Finally I attributed the boost bleed to backpressure pushing the internal wastegate flapper open. The 2.5" DP may have gotten me to 400RWHP if I could just keep the wastegate from blowing open. Like you inferred, my new larger DP with the Tial wastegate should cure some or all of my problems. Hmm, that sounds like the turbo isn't sized or balanced to match your engine and your requirements. What boost/timing/airfuel were you running? How much torque did you make? Quote Link to comment Share on other sites More sharing options...
jgkurz Posted September 22, 2007 Author Share Posted September 22, 2007 Hmm, that sounds like the turbo isn't sized or balanced to match your engine and your requirements. What boost/timing/airfuel were you running? How much torque did you make? You may be right about the turbo sizing but the DP and exhaust upgrade needed to happen anyway. My plan is to go to a GT35R maybe next summer. Check out post #4 on the below thread for my dyno sheet and EFI parameters. http://forums.hybridz.org/showthread.php?t=122406&highlight=dyno Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted September 22, 2007 Share Posted September 22, 2007 John, very nice design. When I designed my 2.5" DP, I really did not have any max HP target in mind. I designed it to be a good, budget upgrade for the stock turbo or a t3/t04 upgrade. Best HP numbers I knew of using that DP was in a '71 with a stock n/a L28 and a t3/t04 @ 23psi that went 11.7 @ 119+ on 225 street tires. I would say on a dyno that would be about equal to what you saw. Amazingly close power output for both cars. He never had any boost creep issues but the external WG and larger diameter is the way to go if you are looking to go beyond 400. Just make sure you have a good 3" mandrel exhaust and free-flow muffler behind it. Quote Link to comment Share on other sites More sharing options...
zguy36 Posted September 22, 2007 Share Posted September 22, 2007 #3 looks like a turd! Nice work on the downpipe, I'd love to see you make your goals. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted September 23, 2007 Author Share Posted September 23, 2007 #3 looks like a turd! Nice work on the downpipe, I'd love to see you make your goals. You would know huh.. . Quote Link to comment Share on other sites More sharing options...
jgkurz Posted September 23, 2007 Author Share Posted September 23, 2007 John, very nice design. When I designed my 2.5" DP, I really did not have any max HP target in mind. I designed it to be a good, budget upgrade for the stock turbo or a t3/t04 upgrade. Best HP numbers I knew of using that DP was in a '71 with a stock n/a L28 and a t3/t04 @ 23psi that went 11.7 @ 119+ on 225 street tires. I would say on a dyno that would be about equal to what you saw. Amazingly close power output for both cars. He never had any boost creep issues but the external WG and larger diameter is the way to go if you are looking to go beyond 400. Just make sure you have a good 3" mandrel exhaust and free-flow muffler behind it. Thank you Scottie. The 11.7 on street tires is encouraging. I'm guessing that was in a 240z so I'll settle for 11.999 with my heavier 280z. Part of my summer project was to improve my exhaust system. I now have a full 3" mandrel system with a straight through muffler. Due to the turbo it's actually quieter then I thought it would be. Quote Link to comment Share on other sites More sharing options...
JustinOlson Posted September 23, 2007 Share Posted September 23, 2007 Good Work John!!! I'm glad to see that you got your car up and running. Are you going to try and run it before rain sets in? I'd love to take a ride in it if you're ever downtown portland. I live near PGE park now. Regards, Justin Quote Link to comment Share on other sites More sharing options...
jgkurz Posted September 23, 2007 Author Share Posted September 23, 2007 Good Work John!!! I'm glad to see that you got your car up and running. Are you going to try and run it before rain sets in? I'd love to take a ride in it if you're ever downtown portland. I live near PGE park now. Regards, Justin Thanks Justin. Looks like PIR is closed already. Woodburn is racing till 10/14. If I can get the car tuned I'll try and make one of the October dates. The fall air should make big HP. Woodburn Drag strip Schedule: Sept. 30 Sun ET Racing & JDRL (Jr. Points End) 9 am Oct. 7 Sun ET Racing / Jr. Fun Day / Powder Puff 9 am Oct 14 Sun ET Racing & Jr. Dragsters 9 am Quote Link to comment Share on other sites More sharing options...
draga240z Posted September 25, 2007 Share Posted September 25, 2007 That is one bad ass Dp, will you be making any more? Quote Link to comment Share on other sites More sharing options...
jgkurz Posted September 25, 2007 Author Share Posted September 25, 2007 That is one bad ass Dp, will you be making any more? Sorry draga240z but this is the only one I'll be making. I'm just too slow at fabricating for it to be worth while. Thank you for the comment though. I would be happy to provide information on where I got the parts and which ones to buy if it would help. BTW, I'm flattered that this post was worthy of your first HybridZ showing. Welcome. Quote Link to comment Share on other sites More sharing options...
ben280zx Posted November 10, 2007 Share Posted November 10, 2007 I would like to have those info "provide information on where I got the parts and which ones to buy if it would help." Quote Link to comment Share on other sites More sharing options...
jgkurz Posted November 10, 2007 Author Share Posted November 10, 2007 I would like to have those info "provide information on where I got the parts and which ones to buy if it would help." I've had great luck with these folks for all my mandrel and exhaust needs. Columbia River Mandrel Bending http://store.racing-solutions.org/ First you would need two 45deg bends. They come in 4" or 6" radius so you have to pick the ones that fits your car the best. 6" is better for flow. The hard part will be finding a flange that mounts to the turbo that you can weld the pipe onto. I lucked out and found my flange on eBay. I don't know of a retail location to buy a flange for the Nissan style turbine hosing. Most likely your turbo outlet will not be 3" so you have to have some sort of taper to the 3" pipe. Columbia River Mandrel also has the 3-bolt flanges to bolt up your exhaust after the downpipe. For the wastegate pipes I used all mandrel 1.5" pipes. There wasn't room for a bellow. I got the wastegate flanges came with the Tial wastegate. Hope that helps. Quote Link to comment Share on other sites More sharing options...
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