My turbo project is up and running... need help with fine tuning
12-14-2003, 11:29 AM
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My turbo project is up and running... need help with fine tuning
Hi Folks, i finally got the ur-q running with the bigger T04E and IC. Still working on some fine tuning and would appreciate some help.
Problem 1:
3rd gear and up the car runs great... at 10 psi the car is much, much faster than the stock turbo at 17psi. Now when i turn up the boost via MBC, any thing past 15psi (in 3rd gear and up) results in a very nasty boost spike in 1st and 2nd gear. Basically the car runs great 3rd 4th 5th gear @ 15psi, but in the first two gears the car spikes to 18 psi and goes lean. Thinking that the wastegate could not react fast enough when my ball and spring MBC opened, I turned down the spring tension on the back of the wastegate using the 6mm allen bolt and that helped a bit.. 2nd gear no longer spikes but first gear still spikes to 18psi.
Any suggestions? is my wastegate simply too small?
Problem 2:
I am really interested in learning how to get more fuel. I am running the stock CIS set to factory specs, and in addition i have an SDS AIC running two 44lbs injectors before the throttle body. at 15 psi @ 6000 rpm I have to run the additional injectors at 100% duty cycle to keep the engine running rich (monitored via A/F guage). This turbo is big enough to run at +22 psi all day long if i can get enough fuel (ya ya in know the air flow meter will be a major restriction). I know the easy answer is to install bigger supplemental injectors (like 80 lbs/hr) but is there any other way? Before anyone suggests... I don't have the budget to convert to EFI at this moment.
All your suggestions and comments are highly appreciated, thanks
Problem 1:
3rd gear and up the car runs great... at 10 psi the car is much, much faster than the stock turbo at 17psi. Now when i turn up the boost via MBC, any thing past 15psi (in 3rd gear and up) results in a very nasty boost spike in 1st and 2nd gear. Basically the car runs great 3rd 4th 5th gear @ 15psi, but in the first two gears the car spikes to 18 psi and goes lean. Thinking that the wastegate could not react fast enough when my ball and spring MBC opened, I turned down the spring tension on the back of the wastegate using the 6mm allen bolt and that helped a bit.. 2nd gear no longer spikes but first gear still spikes to 18psi.
Any suggestions? is my wastegate simply too small?
Problem 2:
I am really interested in learning how to get more fuel. I am running the stock CIS set to factory specs, and in addition i have an SDS AIC running two 44lbs injectors before the throttle body. at 15 psi @ 6000 rpm I have to run the additional injectors at 100% duty cycle to keep the engine running rich (monitored via A/F guage). This turbo is big enough to run at +22 psi all day long if i can get enough fuel (ya ya in know the air flow meter will be a major restriction). I know the easy answer is to install bigger supplemental injectors (like 80 lbs/hr) but is there any other way? Before anyone suggests... I don't have the budget to convert to EFI at this moment.
All your suggestions and comments are highly appreciated, thanks
12-14-2003, 03:05 PM
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Do your additonal injectors have their own FPR or are they using the CIS's.
Basicly I'm curious how much fuel pressure your additional 44lb injectors are running at. Stock system pressure or are they regulated lower?
12-14-2003, 07:34 PM
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Re: EFI fuel injectors at 80 psi!??? talk about a fire hazard!!
And where did you get that info?
Why does it seem everyone's throwing out this fire hazard thing. I know of many high hp EFI cars with system pressures in the 80's and at full boost that's over a 100psi.
Why does it seem everyone's throwing out this fire hazard thing. I know of many high hp EFI cars with system pressures in the 80's and at full boost that's over a 100psi.
12-14-2003, 09:01 PM
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Stock UrS4 fuel pressure at 22psi of boost = 80.8 psi
S4 fuel pressure regulator 4 bar = 58.8psi+22psi of intake manifold pressure=80.8psi system fuel pressure. Sorry to come off a little harsh but man it seems like ever post I reply to about fuel pressure is followed up by a post with the words "fire Hazard" HAHAHA LOL
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12-15-2003, 05:48 AM
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OK, I am going to try the following... do you think I am on the right track
1. Check main fuel pressure to make sure its about 92 psi
2. Check supply voltage at the fuel pump
3. If voltage is low, install a relay so the fuel pump gets power directly from the battery
4. if that still doesn't work, install an additional inline fuel pump, a la Porsche 930.
2. Check supply voltage at the fuel pump
3. If voltage is low, install a relay so the fuel pump gets power directly from the battery
4. if that still doesn't work, install an additional inline fuel pump, a la Porsche 930.
12-15-2003, 05:53 AM
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Re: Bigger CIS injectors
That sounds promising, but I don't know how i would tune the car to run well off-boost... it would be rich all the time as opposed to when boost is high. I suppose i could tweek the CIS air flow sensor plate spring, but wouldn't that add even more intake restriction?