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Finished up an E85 Tune today on a 94 Supra with a built 2J 1700CC ID. To my knowledge this is the first dyno of this turbo on a 2J. When we posted it this evening there was some back lash on the interwebz saying it didn't make enough torque and that it looked lagy. The car is a riot on the street and pulls hard and smooth all the way to red line.
The only issue I had with the tune at all is that he has a knock off greddy ebay exhaust manifold and the waste gate points straight down and on a smaller GEN 2 Precision it will still make 25 psi on waste gate and controlling the turbo is a little tricky. A very experienced local tuner has had this exact issue on turbos like this. Seems common.
During the tuning process I smooth out A/F at 11.7 under WOT or a touch below (I still tune in gasoline with E85 just makes it simpler for me) and I optimized torque all the way through the RPM band down low and then on power runs. After more timing quit making more power I stopped. Not rocket science.
I tuned on my DynoJet 224XLC with win pep 7.
Do you guys see anything inherently wrong with this dyno? Is my dyno calibrated correctly? Could that be what people are complaining about? Or is this just internet trolls being internet trolls.
I don't really see a problem with the graph, although I don't tune much on Precision turbos. If the boost control was resulting in the boost climbing through the rev range then this would artificially make it look like the midrange power and torque was lower than the peak value would suggest.
The "big number" is impressive for a 6062 even for e85. The response isn't dazzling for a 3ltr especially on e85, there are 2jz results online for 6266s on pump fuel that 'look' better, how they drive is something else. If the fuel, ignition and boost control is optimised "it makes what it makes".
Did you do anything to the cams in terms of different grind or adjustable cam gears? Are you using a divided turbo manifold and twin scroll turbine housing? Assuming the boost control is done correctly, those are the biggest knobs for low end torque: turbine housing/manifold, and valve timing. Consider VVTi head and twin scroll for better low end torque.
Also, you started your pull at less than 2500rpm. Lots of those dyno queen sheets start at 3 grand and then scale each axis to make the low end look a little more flattering.
BC 264 cams...non adjustable. Twin scroll manifold and turbo with a 10:1 motor. We have done VVTI on another build but not this one. Honestly the VVTI didn't make as big of a difference as I was hoping it would.
I started all of the pulls at 2K rpm. Interesting to know that about the 3K runs.... I didn't know people where doing that.
I looked at the cam card for the 264 cams and they are basically moderate cams. It's nothing extreme, but it will definitely hurt your low rpm torque due to the later intake valve closing timing and thus lower effective compression due to the intake valve staying open longer in the compression stroke. The overlap isn't too bad. The problem with 2JZ VVTi is that the 2JZ is old. It's 90s variable valve timing. It's better than nothing, but it doesn't have a good phaser range (30 or 40 degrees I think, compared to state of the art of 70 degrees intake and 50 exhaust). It's intake only. Compared to even a 10 year old BMW N54 engine it's far behind the times.
At what rpm are you making boost? I didn't see boost on the dyno sheet. If you don't add VVTi your main option for more low end is to use a smaller turbine A/R to make more boost come on at low rpm, or to go back to stock cams to raise your effective compression ratio at low end. With E85 in the tank, you're not very knock limited, so I'm assuming you've already added as much spark as you feel comfortable with. Either way none of these options are going to work miracles. Stock cams with VVTi combined with smaller turbine A/R all together will probably be noticeable, but you're going to take a hit on peak power. Adding VVTi to your current setup is the only choice that won't hurt peak power, but as you noticed it will be a modest improvement.
OR be happy with the car and don't listen to people on the internet.
The only thing, that one could argue is that little dip in the torque curve. It looks like, that boost hit's then dips a little below target and then picks up again. But other than that, it doesn't look to bad. I've tuned a number of 2JZs on Precision Turbos, so I'll dig up a graph with a similar sized turbo and compare it to yours.
Can you post a log file of the run, with the most vital information?
Don't listen to internet trolls and bench racers, stick to your sensors and dyno feedback, and you'll most likely get the best result. ;)
I suspect a lot of it is trolls being trolls - most don't know what 'laggy' is and think it is the rpm where the engine starts to spool up - come on boost - when it is the time it take to spool up (and down) when in the 'boost' operating range. That said, it does seem to be a little high before starting to spool up - could be the hot side being a little large? On the other hand, you're unlikely, depending how you drive, to accidentally run into it, which could be awkward at the wrong time.
Could that dip be the ECU pulling timing, or boost, if it is set up to monitor and react to indications of detonation?
So I found out why the dyno looked a little weird. Before this car I had been tuning my Z and used 4th gear. The Supra got strapped to the dyno and from habbit I just used 4th gear....and I should have used 5th.
I made no changes to the tune and re dynoed the car in 5th....results are attached.
When you dyno in a higher gear you are taking away some of the transient effects. You give the car more time to spool the turbo. So it makes sense that you would have higher low end torque shown on the latest dyno sheet. Obviously that doesn't mean your car is actually faster, you're just seeing the effect of a different ramp rate basically.
I agree, wont drive any different. Just more consistent with other Supra dynos....and explains the odd dip that was there.