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Old 05-08-2007, 04:17 PM   #1
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Default Should I be able to turn up the boost more?

I put in green top Supra injectors a couple months ago thinking I could turn up the boost from my 7psi with stock 1.8 injectors. My air/fuel was around 13.5-14 with stock injectors and is now 11-11.5 at full throttle. I've read that I want it around 12.5, so I can turn up the boost a little, but I thought I'd be able to boost up to around 10psi at least. My afpr is adjusted all the way in and I have a 190HP fuel pump.

I'm just going through the plans for my car when I go home next week and want my car to be a little faster as I save up for megasquirt.
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Old 05-08-2007, 05:59 PM   #2
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What AFPR do you have?
Sammy, you've got to get a fuel pressure gauge too. I'm was running 10-12psi on my 1.8's and probably still rich with the fuel pressure I'm getting of 100-120psi. You're probably good to at least 12psi if you can get that fuel pressure up. Are you running a restrictor in your boost line to the AFPR? If so, you can remove it to get some serious fuel pressure and feed the injectors more than enough for at least 10psi, probably more along the lines of 12-14psi. Check out my two latest threads about my 305's and Fuel Presure Gauge install. This weekend in Deleware at the dyno day, I'm gonna see if I can safely fuel up to 14psi with 1.8's and about 120psi of pressure. I still have no way if verifying injector duty cycle, but guys say they as much as 90%.

I just did the numbers here http://www.rceng.com/technical.htm
At 80%IDC, should fuel enough for 200whp at 100psi on 305's... that makes for about 12psi of boost... with plenty of room left for an increase in fuel pressure and IDC.

Get a Fuel Pressure Gauge, turn up the pressure, and turn up the boost... then watch your A/F's and pull an extra degree or two of timing. Does anybody else see a problem with my logic... I don't want the guy frying something.
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Old 05-08-2007, 06:08 PM   #3
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other Sam-

it's a BEGi 2025 afpr

no restrictor in boost line

I have a pressure gauge i'll install next week, maybe I'll even try to find your crazy compression lines
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Old 05-08-2007, 07:17 PM   #4
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That's the exact model I use. Dude, with no restrictor, even at 7psi, I bet you're spiking to 100psi and holding 80-90psi of fuel pressure on the top end. If you turn up the boost more, you'll see more fuel pressure. At this point, just dial it up to 10psi and go for a spin. ****, I found out on my first dyno run that I was hitting near 18psi with decent AF's with the exact fuel/timing setup I'm running now. Too bad my clutch wasn't ready. Next Sat will be a different story!

You can ease into the boost slowly for a few runs and watch your AF's... after your happy, try a WOT run.
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Old 05-08-2007, 07:22 PM   #5
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Now THAT's what I wanted to hear! I bought mine from FM in a lapse of judgement, not realizing they were made by BEGi and of course cheaper from BEGi. I even paid the extra $15 for the "installation kit", which, among other things, did not include a restrictor. Anyways, thanks for the good news, Sam (I'm going to call you Sam #2, #2 for short :gay: ).
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Old 05-08-2007, 07:22 PM   #6
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Why do you *need* a FP gauge? Who cares what the FP is, as long there is sufficient fuel?

Yes, I'm sure you easily have enough fuel to get 10 psi out of a T25.
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Old 05-08-2007, 07:24 PM   #7
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That was my rationale for not installing it in the first place. I just keep my WB on the a-pillar and keep an eye on it.
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