Guys with Super Six PP, SC, and turbo's- fuel pressure

[ItalianStallion1]

Here's the situation, and it's sort of funny. I just picked up my first HPP magazine the other day. I do have a Camaro and that's probably why. It's a great magazine and I'll be reading it from now on. Anyway, I was on the can reading it tonight and I was reading about fuel pressure and how a car needs to maintain atmospheric pressure through maximum load. The thing that I was thinking about is that of course big HP cars change to high flow fuel pumps and larger injectors. Of course we're not making a huge jump with 75-100 HP increase but it is relative. Now I know some have not recieved the gains from the Super Six power pack and have said the culpret is PCM tuning. Well, I was thinking that perhaps higher fuel pressure could help. I'm not saying that a huge increase is going to come from this, but, if say we have 275-300 HP on a car then perhaps we should increase the fuel pressure by 4 or 5 PSI over the atmospheric reading. I'm no expert on the technical aspects of our cars, or any cars for that matter. But, I'm learning and I was thinking that this might be something that could help for that little extra bit. Maybe 5-8 HP could be seen, maybe. That's what I hope we could see but I'm thinking the reality might be around 3-4 HP.

So let me know what you think.

[Patrick Javert]

Our computers do this thing, it's called adapting. it wants to keep a air/fuel ratio of 14.7:1 during operation. if you were to increase fuel pressure, the computer would just reduce the width of the fuel pulse, resulting in the same a/f ratio as before. Increasing fuel pressure just increases the amount of fuel an injector CAN spray. It does not adjust the a/f ratio. that requires computer tuning. Our computers learn all the time, unlike other car makers, GM made a "learning computer" that will adapt to environmental factors and adjust things accordingly. if you put little things on one at a time and give the car time to learn the new thing, about 75-100 miles, it'll adjust everything accordingly. doing lots of bolt-on's at once or a major thing, like a sc, turbo, maybe heads/cam, it may get tweaked and throw a ses light at you.

[ItalianStallion1]

<blockquote>quote:</font><hr>Originally posted by Patrick Javert:
Our computers do this thing, it's called adapting. <hr></blockquote>

First don't be a smart a$$. I don't appreciate sarcastic comments regardless of what you think you know about cars. Second, I realize that our cars computers adjust. But you're not understanding my point. My point is that our cars could experience a fuel deficiency when getting better flowing heads, cam, power adder...etc I don't think I've heard of anyone having fuel deficiency problems though. But obviously when increasing the flow of air, you need to increase the flow of fuel, correct?

This idea is a manifest of what I read in HPP magazine. Also, a while back I saw an episode of Horse Power T.V. If I remember correctly they were tuning a fuel injected car and they tuned it just a few PSI and gained a few HP. It wasn't much, just like 4 HP. But, it was something that I thought would be worth a shot to share.

[DominusEtDeusNatus]

You're right. People with heads/cam are running out of fuel. Everyone of them needs bigger injectors. The problem is the programming for bigger injectors hasn't been worked out yet. If you just put the bigger injectors in, it will not do anything. You need programming to go along.

Me and Keith have Walbros intank so they can handle up to 550hp. They are plenty for LS1 H/C cars plus some. This is enough fuel pressure to maintain 50psi up to 550hp. I can hear that pump over my loud exhaust. Stock one would loose psi at WOT, this one keeps it constant. Fuel pressure is not a problem, injectors are.

[Ironman24]

Yup yup, I'm also having some fuel issues. With the blower I couldn't get enough PSI at WOT. I just put an inline pump on to boost the PSI and I also have a Walbro intank on the shelf if needed. I'm still stuck with the stock injectors for now. I haven't done any logging yet with the new pump but my FP gauge says I have plenty of PSI now at WOT. Hopefully we can get some injector/programing solutions soon.

On another note the stock FPR is welded to the fuel rail on the L36 so it would take some modification to put a AFPR in there. But I'm not a big fan of those. Just a pump alone will bump up your FP a few pounds.

[ItalianStallion1]

They say that the fuel pressure should rise one PSI over the atmospheric reading for each pound of boost. I had thought about the fuel pump but I was thinking it would be a bit much. I had already known the injectors wouldn't work because of the computer I was thinking perhaps someone had an idea along with my idea. But, I guess since the FPR is welded then we'll have some issues there.

[bluecmaro96]

Im hoping when keith starts programming he can also program for bigger injectors. dude dont let patrick javert [img]graemlins/rofl.gif[/img] get to you. i suppose hes being a smart*** because he just reads out of books and listens to backyard hick mechanics on how and why a car does something and then replys here. he just feels bad that everytime he posts he gets corrected by the guys who know alot about cars such as magnus, dom, james, bill, and so on

[Patrick Javert]

don't start w/ me. the reason that adding bigger fuel injectors won't work is because the maf will say x amount of air is going into the engine. the computer takes this reading and injects x fuel for y time out of the stock 21.6 lb. injectors. adding say a sc, the maf will tell whatever injectors you have to dump x amount for a new Z time, therefore dumping too much fuel into the cylinders. the computer assumes that the injectors flow at 21.6 lbs. per hour, and will adjust how long to keep them open by how much air is going into the engine. more air=longer pulsewidth of the stock injectors. drop new injectors, say 28 lbs. per hour, and the computer will inject fuel for the same amount of time as beofre, assuming the injectors are still stock for the same time as before, but since mroe fuel can come out of the injectors now, too much fuel will be added, and the car will probably throw a ses light at you. upgrading to 24 or 26 lb. injectors won't cause the car to throw an ses light out, but it's all about giving the car time to adjust to the new flow rate. think of it this way, if you don't clean your injectors, they will flow less than before, but the computer will think they still flow 21.6, so the car could rn lean, but the computer sees that when the o2 sensors come on that you're running lean, so the computer re-adjusts everything based on the new flow rate. since the flow changes are very small, very slowly, the car has time to adapt to the new operating parameters.