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Old 07-19-2003, 08:55 PM   #1
lotusTT
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Default turbo and voltage clamp questions

question #1. For running 4-10 psi, what turbo do you recommend? I currently have a VF34 (not installed yet), but this seems like overkill. Is there something smaller that would provide better results?

question 2. Has anyone ever built their own voltage clamp for the MAP? Any leads as to where to find the voltage it needs to be clamped at? If not, where's the best place to buy one?
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Old 07-19-2003, 09:07 PM   #2
boysetsfire
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I have a split second voltage clamp i can sell you. Let me know.

-Marc
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Old 07-23-2003, 10:56 PM   #3
ImprezaRS dot com
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I have had great results with VF22 kits for the RS turbos, and we got 202whp at 5.8 psi from one with air water IC and 2.5" downpipe with 2 cats. This was at 6000 feet which gives us thinner air and less power.

On my car boost started as low as 2000-2200 rpm, and was 5 psi by 2600rpm, and I got 14 psi by 3000rpm on mine, with the 3" dowpipe!

My personal VF22 kit with AWIC is actually for sale now, email if interested. I could work out a trade for your VF34 and cash, or keep the VF22 and have you use your VF34.

Also, don't bother making your own MAP voltage clamp - ProECM and I tested a zener diode clamp against their voltatge clamp, and the zener diode clamp is unstable - the longer it clamps the MAP voltage as you stay on the gas, the lower the voltage going to the ECU and the leaner you run! AFR and EGT went bad.

A ProECM powerchip comes with the voltage set to limit MAP signal to 34 inches of mercury and will allow the ECU to retard timing and raise injector duty cycle for the low boost it is seeing. So, in testing when I ran normal fuel pressures the EGT's stayed under 1500 in a WOT run to 120mph at 5-7 psi, with just a proECM, walbro fuel pump and stock FPR. This is at 6000 feet so your results may vary, but certainly with 70-75 psi of fuel pressure from a RRFPR you should be fine at sea-level for 5-6 psi with stock timing.

Larry
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Old 07-23-2003, 11:45 PM   #4
akcel
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i too have an ADJUSTABLE voltage clamp split second
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Old 07-24-2003, 02:27 PM   #5
cRayZee
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I think the voltage clamp holds somewhere ~5V. I don't recall the exact voltage. If you're a skilled Electrical engineer, you can probably figure out how to make your own voltage clamp. Having a Zener Diode alone as a clamp probably drew too much current from the signal line, thus reduced the voltage the ecu sees.
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Old 07-24-2003, 02:45 PM   #6
Wedge
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4.75v - 4.8v is around where we had ours.
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Old 07-24-2003, 09:23 PM   #7
akcel
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Quote:
Originally posted by akcel
i too have an ADJUSTABLE voltage clamp split second
and it is for sale...for got to mention that part hah
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