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jgkurz last won the day on June 12 2018

jgkurz had the most liked content!

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About jgkurz

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    Slowest Indian
  • Birthday 11/17/1968

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  1. jgkurz

    Turbine size matters

    Thanks for the comments and re-assurance. The dyno chart is before and after (old turbo vs new turbo). Different dyno's but the same DynoJet model. The fact that the lines match up so perfectly at the starts leads me to believe the data is good. No other changes to the air flow of the engine other than a large 4" inlet to the turbo and a equally large K&N filter. The downpipe is new and all mandrel 3" like before. Here's a pic of the flange we made for the v-band and the new DP. I'll work on the AFR, boost, and timing graphs. P.S. How do you shove 34psi in a 10:1 engine on 93 octane? I know the EVO engines are state-of-the- art but the compression at 34psi would be about 18:1. Just curious how that is even accomplished. I have a friend who gets similar power out of Toyota MR2 engines. Simply astounding your engines stay together. P.S.S. I am pleased you are working on another Z project. I can't wait to see how it comes together.
  2. jgkurz

    Turbine size matters

    I did a full leak-down and compression test recently just prior to the turbo upgrade. All cylinders checked out. I do need to check the plugs as well. I have ordered my new .82 housing and will report back as soon as it is installed and re-dyno'd.
  3. jgkurz

    Turbine size matters

    Excellent info James. Thank you. That EVO has to be a handful at those power levels. It's amazing the drivetrain doesn't fly out of the car. You probably don't remember, but my car was built with much of your advice. You guided me through several build questions on email and over the phone. It's been a LONG time. I think you had your yellow 240 back then. The only thing I regret on my engine is my choice to run low compression. Oh well. I can just run more boost.
  4. jgkurz

    Turbine size matters

    I read through the Perrin link again and it is interesting for sure. Notice the Dynapack dyno is showing flywheel HP and TQ which is different. I initially saw his GTX3582R with the .63 turbine housing reach 497hp so I figured I'd be able to make 455hp again with my old L28. WRONG! His 487 is flywheel. My 455 is rwhp so not the same. 487 crank hp will be in the neighborhood of 414rwhp if 15% drivetrain loss is used. The weird thing about my issue is that the new GTX3576R is worse all around, not just top end. If it was just worse at top end I'd be super confident that the .63 was the issue. I am going to try a .82 but I also may have boost leak issue that needs to be resolved although I have no idea where. On a postive note. if the .63 housing is indeed choking the HP as low 3000rpm there may be significant gains possible across the whole RPM range with the larger .82 housing. I call it pent up demand. Just a theory at this point.
  5. jgkurz

    Turbine size matters

    Hi Bernardd, I have been stubborn about keeping the .63 due to spool but I think it's time to make the change. The dyno shop I work with wants to tap my exhaust manifold to check back pressure, which would prove all this scientifically, but that adds even more cost and time. My turbine is a Tial v-band setup. Is that what JeffP uses? I have not checked my BOV and WG because they seemed to be working as they should. My Tial 44mm wastegate has springs that put me at 13psi with the boost controller off. It is controlling boost well until 22psi. I am bleeding boost after the "stonewall" occurrs. Boost is super stable until then. How would I check my BOV? Just increase BOV spring pressure and run it up to max boost again?
  6. jgkurz

    Turbine size matters

    Thanks for the the link from 2009. It certainly seems to apply here. I even commented haha. I think I'm going to swap in a .82 exhaust turbine after I check for the obvious issues. I was worried about spool so I went with the .63. My guess is that the new (larger) compressor is choked earlier than I expected. Looking at the dyno graphs, the engine goes worse as early as 3K RPM. My hope is that the .82 get's me back to my older dyno results plus a bit better.
  7. jgkurz

    Turbine size matters

    I have read parts of that article in the past. It is an excellent piece. It's amazing that a street 4-cyl can support a GTX3582R.
  8. jgkurz

    Turbine size matters

    The 27psi was with my old turbo. The new turbo hit a wall after 22psi. I tried higher than 22psi but it made no more more and boost would drop back top 22psi again. Changing the Tial v-band turbine housing from a .63 to a .82 might be worth a try but it will cost me ~450.00. That's a lot better than a new turbo I guess. I could sell my .63 for 150-200.00 or so which would help.
  9. jgkurz

    Turbine size matters

    Awesome stuff seattlejester. Thank you for thinking about this with me. My old turbo did not have any anti-surge ports or any surge issues that I could notice. It would jump up to 27psi without too much issue. 27psi was the limit as I was clearly going outside the map on the right at that point. The new turbo does have anti-surge so if I am surging I am not hearing it.
  10. jgkurz

    Turbine size matters

    I really debated between the GTX3076R and the GTX3576R. I thought my engine could support the GTX3576R based on some basic compressor map plotting and my previous dyno results. My intercooler outlet pipes are all 3". The inlet pipes are 2.5" which match the turbo outlet. The intercooler itself is large and seems to be working well based on inlet/outlet heat tests and previous power levels. I've never done a pressure differential test. I will be verifying some basic things like, throttle opening, turbo damage, air cleaner flow and such before I do anything too radical.
  11. jgkurz

    Turbine size matters

    Gollum, Thanks for putting thought into this. Here are the specs to my car: http://fstrnu.net/z/specs.htm I went with the GTX3576R because I thought the GT35R (or the newest version GTX3582R) would be too big. Several Turbo L28 folks run the GT35R with great success. I went smaller than the GT35R, but larger than my old turbo for the exact reasons you mentioned. I wanted to be well inside the surge line. I did the math a while back to plot my compressor map. I will do it again now that I have real world dyno info. I sure hope you are wrong. Other than low compression, the biggest issue with my setup is the intake, head, and exhaust manifold. It would take big $$$ to fix all that properly. The goal of the project was not more peak power, but a more efficient turbo so I could run more power under curve on pump gas. I didn't think for one second I would be going backwards since my old turbo was a such a terrible design, at least on paper.
  12. jgkurz

    Turbine size matters

    Circling back to this thread. I've been working with some people a lot smarter than me and have learned a few things. My GTX3576R is larger than my old turbo in all respects. Garrett claims it will support 600RWHP. Even if that's optimistic, 500RWHP should be possible on a well built/tuned engine. Notice in the below dyno comparison that the GTX3576R (red lines) fell off significantly starting at 4000rpm and was negative at 3000rpm. The old turbo is represented by the blue lines. I have been focused on exhaust pressure and the turbine housing size. Based on the dyno chart, the experts I mentioned above believe the issue is on the intake side air flow. I'm surprised by this since everything is the same as the old turbo, but with a MUCH larger turbo inlet and K&N air cleaner. The investigation continues.
  13. jgkurz

    Turbine size matters

    Yes, on the dyno I always like to use race gas for the safety factor. Cheap insurance. I can safely run 15psi on 92 octane. My recent coolant bypass on cyl 4,5,&6 seems to have helped keep the head much cooler.
  14. Hi all, I had an interesting result on the dyno recently. Years ago I made 455 rwhp @ 27psi boost with my old non-ball bearing customized T4/T3 hybrid. It had a small .50 compressor housing with a 3" inlet and what Innovative called a GT58 wheel. The hot side was a T350 stage V wheel with a .63 housing. I recently upgraded to a very expensive dual ball bearing GTX3576R with a 4" inlet and a Tial vband .63 housing. Nothing else changed on the engine. I like the quick spool so I stuck with a .63 turbine housing. The new turbo made 366rwhp and was done at ~22psi. Adding more boost did not raise HP. That is a 89hp difference. On a modern engine like in an EVO or STI, my GTX3576R turbo could support close to 600HP. Obviously my old L6 can't flow enough air. What I learned is that the old turbine wheel has a 71mm Inducer/62mm Exducer @ 76 trim. The GTX3576R turbine wheel has a 68mm Inducer/62.3 Exducer @ 84 trim so a bit smaller. Another interesting point is that the new ball bearing turbo had a mirror image dyno curve to my new turbo up to 4500rpm or so. The myth that a ball bearing turbo spools sooner is not true, at least with my engine. I am amazed that the slightly smaller turbine wheel caused the 73HP drop. I may try a .82 housing and see if that helps although I am confident it will add turbo lag. -John
  15. The car is on the street most of it's life. I occasionally participate in track days, autocross, and even drag racing on a rare occasion. If I find my self doing more track days I'll add more neg camber. The caster @ 3.5deg is already getting close to my front fender. I might be able to get to 4deg but that's probably the max. How much neg camber would you run for a car like mine that sees both street and track time? Just curious. This weekend I have been invited to a drift event which will be entirely new for me. I will probably be the oldest one there at 50. Ha! I don't plan on ragging on my car too much but I might enjoy sliding around a bit with some friends and family doing the same. I need new tires anyways so I figured why not give it a try.