Were are ya'll getting your check valves from? Also just to make sure the only places I need to use check valves are to the brake booster and to the fuel pressure regulator. Correct?

 

I get mine from NAPA.

You need one for brake booster, and the interior HVAC controls. Dont need one for fuel regulator, or else it wont raise pressure in relation to boost. that is a bad thing.

 

I have an AEM so I don't want the FP regulator to see pressure. But I though I might want to do ahead and let is take pressure out at idle ( ie with vacuum ). Or I could just not let it get a vacuum source at all and use the AEM to adjust for everything.

 

word.

 

what's the reason behind this? I'm not familiar with AEM though.

AEM controls FP too?

 

With the AEM, I can control the pulse width of the injectors based on rpm and boost/vacuum. So I don't need the FP to raise as I see boost. I can just have the AEM increase the pulse width of the injectors as boost comes in.

 

This doesn't make sense...is it something that AEM told you to do, or did you get the suggestion from somewhere else? You will need the fuel pressure to increase with boost in order to maintain flow. Let's say that your base fuel pressure is 40 psi at zero vacuum (WOT naturally aspirated). That is with the atmospheric pressure outside and inside the manifold being equal. Now, if you shove 10 psi of boost into the engine, the manifold pressure is 10 psi, which is fighting that 40 psi of base fuel pressure (as measured relative to the atmosphere, not to the manifold pressure)...and the result is that the injector is only performing at its flow rate at 30 psi, which will be reduced from its 40 psi rate. By increasing the fuel pressure 1:1 with the boost pressure, all you're doing is letting the injector keep up with the boost (fuel pressure relative to manifold pressure, not fuel pressure relative to atmospheric pressure). To take this to an extreme, if your base (zero vacuum) fuel pressure is 40 psi, and you run 40 psi of boost, and you don't have a 1:1 increase in fuel pressure with the regulator, then you won't get any fuel into the engine at all, since the manifold and fuel pressures will be equalized. Of course, you'll probably blow the engine up long before this exact scenario takes place.

But if you want a relatively large check valve, get a Purolator PCV valve number 10001. It has ~1/4" barbs on each end, and is metal. It is very similar to the one that Incon used to sell for something like $20, but you will only pay about $3 at a local parts store.

Mark

 

you must have ALOT of injector capacity (reserves) on your engine if you are not boosting FP 1:1 vs manifold pressure.

 

Okay, I stepping a little bit out of my field of expertise( assuming I have one ) here, but this is my thought. Look at all the pro 5.0 and SSO cars, they have no boost/vacuum reference to there regulators. And they run 20+ psi, easily. The reason you can do this and get away with it, is because air pressure will not cause the effect you think on fluid under pressure. A fluid will not compress, where as air can continue to compress indefinately. So 10psi of air pressure pushing on 38psi of fluid pressure does not equate to 28psi of fuel pressure. It would be more like 36psi of fuel pressure, if that.

 

i am pretty sure you want to put boost on the regulatur. if you increase fuel pressure, your duty cycle will go down. you would need something 70# injectors and some good tuning to do it otherwise.

 

You'd better stock up on head gaskets...lol

Mark

 

Here's some photo proof that you're doing your homework WRONG. I have taken these pictures over the last 2 nights at the World Street Nationals here in Orlando. This first photo is of the pair of fuel pressure regulators on Mike Moran's sick twin turbo Chevy, which has gone 6.26 @ 239 (but certainly not at this track). NOTE THE BOOST REFERENCE HOSES GOING TO THE REGULATORS FROM THE MANIFOLD.

Mark

 

More incorrect homework...here's a photo of the fuel pressure regulator on Lance Styck's car. I think he's running in the 10.5" tire class, which is basically a bunch of SSO cars. NOTE THE BOOST REFERENCE HOSE GOING TO THE REGULATOR FROM THE MANIFOLD.

Mark

 

And yet another photo of how to do it right. This a photo of a random turbocharged car, but keep in mind that the "slowest" qualified car on the property is running mid 8s. NOTE THE BOOST REFERENCE HOSE GOING TO THE REGULATOR FROM THE MANIFOLD.

I have more fuel pressure regulator photos if you need more evidence of how to do it right...but posting pics with this dial-em-up connection is almost more effort than it's worth lol. It's interesting to note that every car that I looked at is running a Weldon regulator. There must be something to it.

Mark

 

Yes, I've yet to see a pro mod, pro 5.0, or sso car without manifold ref to the regulator. Can you say boom?

Mark, I have first hand knowledge of why to use a weldon regulator. With the aeromotive pro regulator, I couldn't get the fp down below 53psi once I switched from a 2025 to a 2035. We weren't sure if it was the reg or the -6 return. So we tried a Weldon 2040 that Ed had on his car. Voila! We could now get the fp down below 35. This tells me two things............ -6 return is all you need to make an a$$load of power and the 2040 is a far better regulator.

 

I got mine from a pet store! I bought four of them... at $2.00 each(canadian)

 

I agree with all of the above, your FP must be referenced to manifold absolute pressure.
You must maintain a constant pressure difference between your manifold and fuel pressure.

There's actually no difference between vacuum or boost, its all pressure - just depends on your starting point - us humans exist at approx 14psi, so less than that we call vacuum and more than that we call pressure!

eliot.

 

Okay people. I conceeded a while ago, LOL. I really didn't do any homework on the subject, just went on an assumption ( a wrong one ) of no FMU no boost reference required. I hooked up the vacuum hose to the requlator the day this post happened.