rx7tt95

For ease of following the progress, my first report on the installation of the GT4082 can be seen here:
https://www.rx7club.com/forum/showth...hreadid=278226
with some additional points/observations at http://www.nopistons.com/forums/inde...howtopic=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 :-)

rx7tt95

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.

rx7tt95

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.

Badog

Solid numbers from a Clayton dyno. Thank you for not adding in a correction factor for us and letting us see the raw results.

rx7tt95

Here's just the last dyno run by itself. Last one. Have to run!

CCarlisi

I have to say I thought you would have produced more peak power or had better low end response. For comparison Zoomzoom made 400rwhp at 6,000 rpms (above that had boost control issues) and 300rwhp at 4,000 rpms on a reman motor with a 3540. Comparing his KD dynojet chart to your chart that lists rpm it appears he made over 100hp more at 4,000 without giving anything up in terms of peak power. Also I tend to think he would have had an even higher peak number if he was able to get the boost controller to hold above 6000rpms.

What was your timing like at 15psi?

In any event, that's a lot of power

vosko

iTrader: (4)

the last chart looks nice.....very smooth! he has a big turbo. i'm surprised you got it that smooth. the GT35/40 is much better for low boost. wait till he turns up the boost....

IRPerformance

iTrader: (41)

considering gt40

rx7tt95

Total advance was 15 degrees up top. My EGT maxed out at 1000 degrees Celcius with the EGT IN FRONT of the turbo, not behind. Pretty damn safe so perhaps I could get more agressive with my tuning. I'll be posting my map on the Datalogit forum. I will have to say I'm no expert tuner, competent, but not expert. Also the 40 hot side is larger than the 35/40 and I have an undivided manifold which hurts low/midrange response time. And remember, unlike a dynojet, all my figures are uncorrected.

Naturally, with stock ports, you're going to have a stronger low/midrange. There's almost no way around it.

Looking at my first comment above, also realize I wanted things pretty safe. I have no doubt in my mind a better tuner such as Tony or Steve Kan could make things MUCH stronger. I left the bottom end of things alone and really concentrated on the top. If you look at my first post, I made the comment that I was still in the 10's from about 3500 to 5500 or so. Work to be done there undoubtedly. And lastly, I ported this engine myself and I've never felt it was very strong just judging by the power pulses coming out the tailpipe. Then again, I did have a slight run-in with a chunck of concrete in the middle of the road. Managed to dent my Borla XR1 quite heavily and crack the aluminum cross brace just behind it. Maybe that's an issue?

Here's the way I see it. Put in fresh plugs. Change the oil. Get a real tuner. Change out some of the suspect items on my car (exhaust from the downpipe back) and tune on a dynojet with a correction factor. I see well over 406hp at a fairly sane boost level, definitely numbers that would squash a 35R. Switch to the 88mm GT40 wheel which flows more air and is more efficient at lower boost levels. There's probably another 20-30hp in that alone. I'd have to compare the GT40 82mm compressor with that of the 35R. The 82 really likes high boost levels and I am actually contemplating finding someone to tune the car for me on race gas at say 25psi. THAT should be interesting.

Wargasm

It would be great to see the next set of dynos on a Dynojet just because that's what most of us use on here. It would make it a little easier to compare setups.

enzo250

I hate using dynojets. Their HP readings are inflated. And there really no good for anything besides WOT pulls. But yet this is what most people use.

rx7tt95

That's pretty true, Enzo. Lots of people get caught up in the Dynojet hype. There is one in town so I may go and do a bit more tuning in the low/midrange after I get some feedback on my maps. Not sure what the hp diff would be between say 11.1:1 and 11.8:1 but I would guess another 15-20hp or so. It's easy to get caught up in a numbers game but with so many variables it's really hard to comparet two cars.

The Clayton I tune on is in need of new bearings so there may be more parasitic drag than normal for that unit (it has two rollers and an electric brake) and it'll also do the peak hold style runs which are incredibly effective for tuning. I did all my runs inertia (dynojet) style. Regardless, the Clayton does load the car more than a dynojet.

Poweraxel

amen.. eddy current units such as Dyno Dymanics,Mustang Dyno are much better for overall tuning... Dynapacks are also great units

Jason

iTrader: (5)

If they had loading turned off on the clayton dyno then its not putting any load on the car and simply spinning the rollers like a dynojet. The only difference is the weight of the rollers which they can compensate for in the software. Usually if the bearings are loud they just need to grease them and not replace them.
You would pickup around 5-10 HP from leaning it out to 11.8.

Jason

SPOautos

Dude 1000C is NOT safe, thats over 1800F. Even in front of the turbo thats not safe.

You sure its not 1000F

STEPHEN

rx7tt95

Yes, guage is a GReddy in celcius. Behind the turbine it's about 750-780 celcius. Exhaust is ported as well. I've been told anything under 1100 is safe.

SPOautos

Have you actually measured it behind the turbo? I've heard its only around a 150 difference at most.

The melting point of alum is like 1400F

STEPHEN

rx7tt95

There is inherently more friction in the Clyaton design than the dynojet, loaded or unloaded. This isn't your average run of the mill Clayton either. It's only one of three in the world currently and is somewhat different in design/operation from other Claytons. They've been having to replace bearings on a regular basis. I'm sure it wasn't "optimal".

If I use any sort of a realistic correction percentage factor that most others use for Clayton/Mustang dynos, I'm at about 460hp. And this is the smaller of the GT40's. The BB GT40R will more than likely be an awesome turbo on a 7.

rx7tt95

Well let's just say there are no knock readings and no other issues with those exhaust temps. I was actually running hotter with the old turbo. I've dropped about 50 degrees celcius switching turbos.

The official melting point of aluminum is 660 degrees celcius or 1220 degres Fahrenheit. My cruise temps before the turbo are around 700 C at 80mph. The Aluminum housings are surrounded with coolant passages. The aluminum never reaches anywhere near the exhaust gas temps.

http://www.noblemind.com/search.exe?...ng+Point&var=2

SPOautos

Well, different people have different opinions I guess but I'd hardly call 1100C egt's safe. I wouldnt want mine more than 900ish C before the turbo, I'd even consider that on the hot side and wouldnt want to run it for more than a few seconds but to each thier own

STEPHEN

Jason

iTrader: (5)

Not to argue with you but I own a Mustang dyno and you can turn off the loading so the only load on the car is the rollers, similar to a dynojet. From what I have heard of the clayton is does the samething. There will still be a % difference between the two dynos and from what I have seen its 3-5%.

Jason

onenrg1

Are you using the GT40 or the GT40R. Your signature says GT40R so thats what I assume that you are using. Thanks

rx7tt95

I would agree with you Jason. But the Dynojet numbers are all corrected and the Claytons are not. Thus the difference :-)

onenerg1, sig isn't updated. Was planning on a GT40 R but could not get a hold of one in time. So as sort of an experiment, I got my hands on a plain bearing GT40 with the smaller 82mm compressor wheel. Check out my first post about the GT4082 (link at the top of this thread), has all the details :-)

Stephen has me worried. Anyone else want to chime in on EGT's? I've had several people on this forum comment they were producing EGT's in the range of 950 degrees celcius AFTER the turbo.

enzo250

you should be absolutely fine with your egt's.
Maybe stephen is thinking piston motor.(shame on you!)

I have seen rotory's survive with over 2000 F

pluto

mainfold temperature is usually around 150C-200C above the downpipe location so I wouldn't go over 1000C before the turbo.