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What fuel pressure with whipple SC 6psi

Joined
31 May 2006
Messages
786
Location
Hazerswoude, The Netherlands
My car is now running again after finally finding out the igniter was malfunctioning (see my topic on this) causing it to run on 5 cil.

As I am working on the car anyway and as with a dynorun some time ago the A/F was too lean, I checked the fuelpressure: with vacuumhose connected to the FPR I got about 36 psi at idle.
I turned the adjustment screw on the FPR in about 1 1/2 turns and am now getting 40 psi at idle.
What is recommended fuelpressure value as I can't find anything on this in the Comptech installation manual.
 
Tried to use my Mityvac on the FPR to test fuelpressure at 6 psi and found out I couldn't get the FPR pressurized.
So took off the FPR.
Found out that next to the vacuumhose connector on it, there is a hex blanking bolt blocking off a 2nd connector hole. This bolt has been drilled with a small (probably 1 mm) hole, I know this is not the way it came from Comptech, the FPR comes from Comptech with the blind hex bolt.

The hole is probably made to flatten out the fast rise and fall of boost/vacuum to the FPR and in this way flattening out the fuelpressure somewhat (I know this is sometimes done with Turbo engines).

Did some testing with and without the bleedhole:
With FPR as dialed in by the CTSC installer at idle:
-with vacuumhose connected, with bleedhole open 36 psi, bleedhole blocked 39 psi
-with the vacuumhose disconnected 50 psi/50 psi

With the FPR screw in 1 1/2 turns so raised the pressure somewhat:
-with vacuumhose connected, with the bleedhole open 39 psi, bleedhole blocked 42 psi
-with vacuumhose disconnected 53 psi/53 psi
At 6 psi boost with the Mityvac (obviously with the bleedhole blocked) 85 psi

So what should I do, keep it as it is with the drilled blanking bolt, as this is clearly done by the workshop who did the install in the US so probably with the purpose as described above, or should I return it to stock so put a new blind hex bolt in??



Anyone??
 
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What.... that is a low reading....36 to 40.
If you are running the low boost whipple on a 3.0 litre obd 1, then you should be around 48 to start I would believe and is true for me.
I am turned up to 50-52 at idle without the a/c running just to be safe.
I have video and posts of this in this section.
Video of my fuel pressure regulator on the dyno.
My RRFPR is the Big Blue Vortex.
Are you running the stock injectors?
Are you running this same RRFPR?
What is the diameter of your pulley on your whipple?
Trev
 
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What.... that is a low reading....36 to 40.
If you are running the low boost whipple on a 3.0 litre obd 1, then you should be around 48 to start I would believe and is true for me.
I am turned up to 50-52 at idle without the a/c running just to be safe.
I have video and posts of this in this section.
Video of my fuel pressure regulator on the dyno.
My RRFPR is the Big Blue Vortex.
Are you running the stock injectors?
Are you running this same RRFPR?
What is the diameter of your pulley on your whipple?
Trev

Trev,

My car is a '98 3.2L OBD2

I have left the fuel pressure adjustment screw turned up 1 1/2 turn as compared to how it was before and am now quite close to the values you posted in a earlier topic I think.
You wrote there:
I have the following readings with stock engine.
At idle anyways!!!
Here are my readings at Idle.
45 psi with the vacuum hose attached to the fuel pressure regulator.
The manual shows 36-44 psi.


I am now at 39/42 psi

52 psi with the vacuum hose disconnected to the fuel pressure regulator.
The manual shows 46-53 psi.


I am now at 52 psi

Where did you find these values as by the manual? My CTSC manual doesn't give any fuel pressure values.

I am however still unsure as to if I should block the bypass leak hole or not, with this hole the vacuum and boost is slowed down and thus the fuel pressure rises and loweres slower as compared to when the bypass hole were blocked.
 
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Stock fuel pressure is:
263 & 264 of the 91 manual that is on line. (11-87)
That is what I was told to set my base idle at.
From there the pressure rises vs boost psi.
To get further help with your system you should call the CT-Eng group or maybe
Shad @ Driving Ambition @ 1-916-861-0032.
I would not mess with the RRFPR until talking to them.
They can confirm your starting psi as well.
I started with 48 psi and left it on the third dyno run at 52 psi.
Better safe than sorry for me.
Let us know.
Trev
 
Trev,
Thanks a lot for sharing Shad's number.
Just called him and he was like a fountain of knowledge on the NSX and CTSC :biggrin:

When telling him on my 5 cil running ignition problem, he immediatly told me that the igniter giving up is a known cause:frown:, told me sorry that he didn't see my topic on that and failed to advise.

As far as the A/F at my dyno is concerned, he wasn't surprised that it showed quite lean, as it was measured at the exhaust tip and that is quite commonly showing lean as a result of the cats he told me.

As far as the AFPR bleedhole is concerned: he told this is as it should be on a low boost 3.2L setup, only on the high boost setup it should be blocked.
He advised me not to look too much at the A/F from the dynotest, but to concentrate on the fuel pressure, as this does seem low on my car.
He advised about 44 psi at idle with vacuum hose connected and close to 60 psi with vacuum hose disconnected. On full boost of 6 psi I should see about 90 psi.
So it seems I will have to raise the fuel pressure even a bit more than I already did.:rolleyes:
 
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Yah, just what I thought.....lol
Trev
 
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