Sorry for the cross-forum post...I did it to them last time :-)



http://www.rx7club.com/forum/showthread.ph...threadid=283479

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! https://www.nopistons.com/forums/pub...#>/BURNOUT.gif

I try not to go there unless the traffic is down here. https://www.nopistons.com/forums/pub...DIR#>/wink.png



Oh, and I'm banned from some of the sections like the one your post is in.

Somebody must be talking out their yin-yang and can't stand the heat when they get called out for it. https://www.nopistons.com/forums/pub...DIR#>/wink.png

No ****, really? I'll post everything here as well then!

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 :-)

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.

Here are the same 7-10 runs but with rpm. Starts at 2500 rpm and goes in 500 rpm increments up to 8500. Hp goes to 410 again.

Here's just the last dyno run by itself.

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.

Please note that I am not using P19/20. 1.1kg falls under P18. I use P19/20 as a safety net for unwanted overboost situations. I've since decided that I need to tune P19 a bit closer to optimal as the PFC takes P19 into account as well.



Trailing map.

Here's the split between front and trailing.

Here's the Settings 3 table so you can see what the map reference is. I start at 1000 rpm and top out at 8800 rpm. P10 is vacuum. P18 is 1.1kg

yeah i think your tuning around peak is nice and safe (just read the both threads), but next time on the dyno id work on the rpm before peak hp and the transition into boost. i was amazed at the difference cleaning up the map going into boost made on the street

I'm scheduled for a Steve Kan tuning session some time the middle of April I believe when he's flying into Florida. Going to let the master take over! https://www.nopistons.com/forums/pub...1047683894.gif

Cool. Hopefully you will get some much higher #s..

406 at 1 kilo isn't bad first time on the dyno IMO, I think Kan will pull out a lot more, like you said, let the master take over. Good **** man.

I loaded in a more agressive timing map and the low-end midrange seems to have improved. I may take her to a local dynojet for a few runs here soon as well. I have several full timing maps for leading/trailing with different split that I can load quickly and try out on the dyno. I think if I get my tuning sorted a bit more and take care of some of the anciliary items like exhaust (higher flowing unit), plugs, etc., I'll be quite happy. It's pretty easy as it is to blow most cars off the road. 996's only require part throttle. https://www.nopistons.com/forums/pub...#>/BURNOUT.gif 996TT's get full throttle. https://www.nopistons.com/forums/pub...1047683473.gif

I wish everyone would frequent the dyno. Nice to see hard #s on modifications etc.

Where is torque peak in RPM and column? Looks like you're leaving about 30-40rwhp on the table. Tell me when she peaks and what the EGT is doing there and after.

Couldn't get the torque reading to work for some reason so there's no data. EGT peaks about 8K rpm and stays there. Had a brief run-in with a new M3 on a deserted stretch of road. Managed to get up to about a buck 40 and saw 950 on the EGT gauge. Was at 1000 on the dyno. And yes, I left the M3 pretty hard https://www.nopistons.com/forums/pub...#>/BURNOUT.gif



On the dyno, she pulls quickly to about 7500 rpm and slows down a bit from there to 8200. I chickened out and didn't run her all the way to 8500. Power doesn't seem to be falling off much and I think it would pull a bit harder up there with more consistent timing. I need to go in and tune at P19.

Looks good Michel, glad to see some of your hard work and devotion pay off. Thanks for not making me go to 7club to read it.

Michel, I might have missed them, but what are the specs on your turbo? I've found a new GT4088 for 815. A reman GT40 for 589. Opinions on either?



Also, what are your spool characteristics? When does it come on during street driving? I'm currently running a Garrett 60-1 (.70/1.15) with an HKS cast manifold on a 13B-RE 1/2 BP. When I go to a new turbo, I'll be using a tubular manifold with 15" runners, so I expect to get somewhat better spool up from that.



Basically, my main concern is keeping a decent spool up, as I use the car for autocross, some drift, and the occasional drag strip run.



Thanks,



Reese

I'm able to get 17psi by 4K rpm on the dyno, a bit sooner on the street. Good response down low and on the highway in 5th where I'm able to just punch it and go. I have the smaller version of the GT40, the 4082. My rear housing is a .94. I believe the smallest stock rear housing on the 4088 is 1.19.



I'd go with the new turbo hands down. I've heard that the GT stuff is dynamically balanced in two planes (for lack of being able to explain the more technical answer) and only the Japanese have perfected this technique. At least two machines are headed (or are here) in the US currently that will be able to balance the GT stuff.



The GT turbines are so much more agressive than anything else out there that spool up vs. size is really good. Transient response is also very good.

Reese is trying to be sneaky and upgrade without telling his family!! BUSTED!!



Rx7tt95, I'm glad to hear that everything is working so well. Did you have a chance to get back on the dyno after you adjusted your timing yet?? I'm really interested to see what you put down after that. Good luck!!



Zach

Haven't hit the dyno yet to fiddle more. I may try to spend more time and get my pump gas maps looking great and have Steve Kan tune the car on race gas at higher boost levels. Right now he's coming out to Florida on April 24 to tune a bunch of cars.

Michel