Gt4088 Dyno Numbers
03-16-2004, 01:25 PM
#1
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Sorry for the cross-forum post...I did it to them last time :-)
http://www.rx7club.com/forum/showthread.ph...threadid=283479
http://www.rx7club.com/forum/showthread.ph...threadid=283479
03-17-2004, 11:00 PM
#2
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Discussion is getting pretty interesting on this on the other forum. I've posted my leading/trailing timing maps and I'm hoping to acquire some worthwhile feedback. So if you have any, or just want to read, stop by! 
03-24-2004, 10:00 PM
#6
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For ease of following the progress, my first report on the installation of the GT4082 can be seen here:
http://www.rx7club.com/forum/showth...threadid=278226
with some additional points/observations at https://www.nopistons.com/forums/ind...showtopic=36931
So. On to business. I had the chance to dyno tune the car today. The dynamometer is a Clayton dynojet capable of inertial as well as peak hold style (it stops the car from accelerating and measures hp/air fuel, etc..). I chose to go with inertia style runs as they're much easier on the car but not the best way to tune. In total, I spent about 1.5 hours on the dyno and made 10 runs. Conditions were about 80 degrees with high humidity (S. Florida). Old plugs, old oil, pretty much how I run her on the street. Car was kept running between runs, no ice, just the fans and nothing funny. The Clayton DOES NOT correct for temperature, humidity, barometer, altitude or anything else. All numbers are raw. As such, the Clayton reads close to but not exactly like a Dynojet, typically about 10% low. It's also a double roller setup and the rollers were quite noisy (new bearings needed?). So with all that I managed an ok 406RWHP at 15-16psi of boost (1.1kg) on pump gas. My air fuel ratios were 11:1 pretty much across the board from 5.5K on up, richer below, in the 10's (need more work there!). Max advanced timing was 15 degrees and my split was 7 degrees. I started out at 12 degrees total advance and 9 degrees split.
My first run was 390 (with a cold intercooler/car) so I didn't improve hp wise a great deal but I did smooth the curve out and fatten up the midrange. Full boost is at 4K rpm on the dyno in 4th gear (all pulls in 4th.) I'll post a few dyno runs here. The printouts are huge and take up a full page so they're a little hard to read. If you'd like a full-size version in high res format, e-mail me and I'll send it to you.
Anyway, the bottom row shows speed on the first 6 runs starting at 50mph and increasing by 5mp, topping out at 150. The HP runs along the left side, starts at 60 and increases by 10hp per line, maxing out at 400. The first runs are the ones with the weak midrange. All mods are listed in my sig (but not quite up to date turbo wise :-)
http://www.rx7club.com/forum/showth...threadid=278226
with some additional points/observations at https://www.nopistons.com/forums/ind...showtopic=36931
So. On to business. I had the chance to dyno tune the car today. The dynamometer is a Clayton dynojet capable of inertial as well as peak hold style (it stops the car from accelerating and measures hp/air fuel, etc..). I chose to go with inertia style runs as they're much easier on the car but not the best way to tune. In total, I spent about 1.5 hours on the dyno and made 10 runs. Conditions were about 80 degrees with high humidity (S. Florida). Old plugs, old oil, pretty much how I run her on the street. Car was kept running between runs, no ice, just the fans and nothing funny. The Clayton DOES NOT correct for temperature, humidity, barometer, altitude or anything else. All numbers are raw. As such, the Clayton reads close to but not exactly like a Dynojet, typically about 10% low. It's also a double roller setup and the rollers were quite noisy (new bearings needed?). So with all that I managed an ok 406RWHP at 15-16psi of boost (1.1kg) on pump gas. My air fuel ratios were 11:1 pretty much across the board from 5.5K on up, richer below, in the 10's (need more work there!). Max advanced timing was 15 degrees and my split was 7 degrees. I started out at 12 degrees total advance and 9 degrees split.
My first run was 390 (with a cold intercooler/car) so I didn't improve hp wise a great deal but I did smooth the curve out and fatten up the midrange. Full boost is at 4K rpm on the dyno in 4th gear (all pulls in 4th.) I'll post a few dyno runs here. The printouts are huge and take up a full page so they're a little hard to read. If you'd like a full-size version in high res format, e-mail me and I'll send it to you.
Anyway, the bottom row shows speed on the first 6 runs starting at 50mph and increasing by 5mp, topping out at 150. The HP runs along the left side, starts at 60 and increases by 10hp per line, maxing out at 400. The first runs are the ones with the weak midrange. All mods are listed in my sig (but not quite up to date turbo wise :-)
03-24-2004, 10:02 PM
#7
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here's runs 7-10. Same start point for speed (50) and hp (60) but the speed goes up to 155mph and the hp up to 410. Last run is the highest where I revved it out to 8200 (chickened out going to 8500) and it was a bit rich. I could have probably made 410 pretty easy.
03-24-2004, 10:10 PM
#10
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There was some discussion about my EGT's being at about 1000 celcius with some feeling they're too high and some feeling they're fine given my a/f ratios. On the street I have yet to see above 900 celcius. Regardless, I'll repost my timing maps. I've had a discussion with Chrispeed and a few other individuals who think my timing is not advanced enough in the bottom and midrange and the transition is not smooth. So I'm working on both. Steve Kan is coming into town some time in April to hopefully tune some cars and I've signed up to go to him as well.
I looked at the log on my last run and timing was 13 degrees, not 15 like it's set on the PFC...RETed mentioned that one should calibrate your EGT. Once you've established a safe a/f ratio (which I have), you can establish a safe EGT. I'm going to post a screen capture of my timing maps. Leading, trailing and split. Let me know what you think! My a/f ratios were about 11.1:1.
I've done a bit more research about potential differences between the particular Clayton I dyno'd on and a Dynojet. They do lots of BMW/Porsche stuff. M5's tend to put down about 330rwhp on the clayton, 345 on the dynojet. So my numbers are definitely lower than what they would read on a dynojet.
I looked at the log on my last run and timing was 13 degrees, not 15 like it's set on the PFC...RETed mentioned that one should calibrate your EGT. Once you've established a safe a/f ratio (which I have), you can establish a safe EGT. I'm going to post a screen capture of my timing maps. Leading, trailing and split. Let me know what you think! My a/f ratios were about 11.1:1.
I've done a bit more research about potential differences between the particular Clayton I dyno'd on and a Dynojet. They do lots of BMW/Porsche stuff. M5's tend to put down about 330rwhp on the clayton, 345 on the dynojet. So my numbers are definitely lower than what they would read on a dynojet.