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Went for a drive tonight, boost set at 16 psi, T66 .70 P-trim, cast manifold, FJO wideband, 93 octane and a Palm'n'stein OBD2 data logger. BONE stock fuel system, down to the fuel pulsation dampener and MAF.

First off, I think there is incorrect information on MKIV.com about what the turbo pressure sensor does. In my car, it does NOT effect fuel pump voltage. We tested this with a voltmeter. I had sold my BCC, but then realized I might want the 9/12v operation for the loud walbro pumps. I looked at the repair manual, and it states that fuel pump voltage is based on airflow, and doesn't mention the TPS anywhere. So I unplugged the turbo pressure sensor and when for a drive. No boost cut and fuel pump voltage was fine, going to 12.8v at around 3.5k in 2nd. Or maybe this was because I unplugged the electrical connector for the TPS, and not the pressure source?

Secondly, I believe there is a misconception as to how much power the stock fuel system can support. At 16 psi, a/f was ~10.4 decreasing to 10.3 or 10.2 at redline. I currently don't have a fuel controller, I'm waiting on a GReddy E Manage. The only reason it wasn't running even richer than that is my O2 sensor is fouled, causing negative fuel trims at WOT.

Anyways, lets suppose WOT duty cycle was 100% at 10.2:1 and fuel pressure wasn't dropping at all (I won't know for sure what it is until I get my E Manage). Then if I leaned it out to 11.5:1, duty cycle would be 88%. While that is still too high for extened pulls (supposedly the injector drivers themselves can overheat and fail - side-mount injcetors don't overheat), an increase in fuel pressure could easily bring it down to 80% at 18 psi. I know the cast manifold won't flow as much as a header, but based on other people's experiences I should be making at least 500 rwhp at 18 psi on the stock MAF (I do have a FMIC).

Of course, I DON'T recommend pushing the fuel system unless you had an accurate way of monitoring a/fs or at least knock. And EGT gauge won't cut it.

If anyone cares, the highest airflow the logger reported was 49 lbs/min (highest at BPU was 43). After a few pulls, timing got as low as 20 from 5200-5700, increasing to 23 at 6000+. By contrast, the base timing map (no knock, assuming the turbo is already spooled) _appears_ to be 19 @ 4k, 20 @ 4.25k, 22 @ 4.75k, 23 @ 5.5k+. This is way better timing than I ever got BPU.

Hope this helps someone,
Grant
'97 T66 6-speed
 
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good info, thanx!
how do you like the FJO BTW? did you get the regular display or that LED display?

also, I guess you are still using stock MAF, would that be sufficient for the power you're making? would VPC help? I'm thinking of getting one cuz I plan to go single later.
what is this E-manage unit? what does it do? is it like the Apex AFC?
 

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Discussion Starter #3
I have the regular digital display for the FJO. Its the bomb. Only problem is I oringally bought one hoping to cover the cost by renting it to a few people, but now everyone was one, lol.

The GReddy E-Manage a piggy back controller, but it has some of the resolution and functions of a stand alone. It can control 16x16 fuel and timing correction maps, as well as an additional injetor 16x16 map which I am going to use for water injection. It can also datalog all of it's inputs and outputs (so it can log injector duty cycle). It can also be calibrated for larger injectors and mass air sensors. With all the harness it was about $400 shipped from Mohd. It would be difficult wiring it up without a Field's harness though. LOTS of wires to cut and splice.

I think the stock MAF is probably pretty big restriction, I'm going dual MAF with the help of the E Manage.
 
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W/ the e-manage, can you run larger injectors and just buy a speed density meter? This would delete the necessity for those overpriced VPC's
 

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I put a T66 RPS kit on a '97 Auto... I believe the owner dynoed 521RWHP(could have been 524) with stock fuel...

He had a wideband on the car while dynoing and the A/F never went above 11:1...
 

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Discussion Starter #7
MaxPrime said:
W/ the e-manage, can you run larger injectors and just buy a speed density meter? This would delete the necessity for those overpriced VPC's
It cannot do speed density, but it is designed to be easily calibrated with larger MAFs and injectors.
 
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