Fuel pressure readings - NA1 with Whipple CTSC

[nsxto]

Hey guys

Can someone confirm what FP readings should be expected for an NA1 with the old Whipple, no fuel pump resistor and 'bumped' stock FPR ? I have read that it should be around 40 psi, but then again, the wiki SC section says that it should be 100?

Thanks

 

[goldNSX]

100 psi under full boost.

 

[jwmelvin]

What is a bumped stock FPR? The original kit came with a rising-rate FPR, which I believe is linear to atmospheric and then increases at a higher rate in boost. I believe you may be asking about the idle pressure, i.e., at full vacuum? That’s the most convenient pressure to measure and should be at the stock level, 36-40 if I’m remembering right. The “full boost” pressure depends on how much boost you are running but can be 100 psi or more. Less if your fuel pump is dying and trying to destroy your engine.

 

[goldNSX]

That's correct. If the system is low-boost, without an AEM it should have the CT FPR which is preset to 40-45 psi at idle. At WOT under full boost it raises the fuel pressure to 80-100 psi. The value at idle determines how high it will go at WOT which determines AFR.

 

[nsxto]

Thanks for the input guys. I am waiting for my gauge to arrive - I will be installing it this weekend after I rebuild the fuel line going from the filter to the injector rail. So I just want to make sure the pressure is up to spec.

As I mentioned, I have the old whipple, no fuel resistor and the stock ecu with a Comptech sticker on it. I have seen a lot of old pictures of the first whipple setups and it seems that most of the kits at that time shipped with a big ugly red FPR. I don't have one of these fancy FPRs. Mine appears to be 'stock' but with a little ding in it. I spoke to one of the local NSX techs here and he said that back in the day, some preferred using the stock FPR so they modified it by bumping the top side with a socket. Sounds weird, but thats the story as far as i know

BTW, regarding boost, its the stock pulley with the old setup, not the enhanced high boost pulley. So I guess for this setup, idle pressure should be around 40psi and full throttle up to 100psi?

Thanks

 

[goldNSX]

Much more essential than the base fuel pressure at idle are the readings of AFR under boost.

 

[jwmelvin]

I couldn’t agree more, having bought a car with the original setup, gone through a process of getting it working “right,” and then ultimately replacing all of the fueling arrangement with a piggyback. You need to know what your AFR is, not just the fuel pressure. Weak fuel pressure is certainly a symptom of issues but can’t be used to adequately tune in the absence of knowing AFR.

I can’t say the primitive CTSC fueling caused my engine issues but I can say it’s a lot more expensive to rebuild an NSX engine than to add a controllable fueling system and AFR monitoring.

 

[goldNSX]

+1

An AFR gauge is mandatory in the CTSC setup because it's all about fuel with this system.

 

[nsxto]

Thanks guys, I do have an AEM Series 2 and a UEGO upgrade waiting to be installed - that comes after I get this thing back up and running so I can drive it to the shop lol
I will put up a detailed post on my fun with the previous setup one of these days haha
cheers