Ted B

iTrader: (6)

It's not a matter of engineering, but rather how the ECU responds to increasing fuel pressure that renders this option relatively useless. Why? If the fuel pressure is raised, it causes an unexpected richened mixture across the board. The ECU simply resorts to its adaptive strategy while in closed loop and shortens the injector pulse to bring everything back to stoich. It applies this correction globally, and recalculates its WOT fuel extrapolation to bring everything back to where it was.

So long as the pressure differential between the injector pressure and manifold pressure stays relatively constant (and it is designed to do so), there is nothing to be gained by altering the fuel pressure. So long as injector capacity is properly sized, the ECU settings rescaled, and the fuel pump adequate, there should be no tuning issues, and there are plenty of EVOs here making well in excess of 400hp without any fuel pressure related tuning issues.

TrinaBabe

iTrader: (3)

Ted... I think we all understand how the system works. Im not trying to be mean to anyone, you obviously seem to know yer ****. The point of the matter is I would much rather give myself an option if I need it later. I know many people that have maxxed out 660s and get around it by raising the fuel pressure. Also, if you want to get so technical I assume you know the difference of the dead time between injectors size of 660 compared to larger? I would rather have quick spurts of gas frequently as apposed to very large squirts of gas slowly. We all understand how it works... for some reason you are trying to tell people that have built many many 10 second cars that it is worthless for them to have a FPR but for some reason they all do it.

I was asking for help, I don't care to know how much any person here knows compared to myself. I am trying to reach a goal. I do understand the fundamentals of building a well built car. I was trying to see how difficult or easy this mission would be. I will never stop with this car... either it will become a straight track car or a drag car. For now I want a track car (Hence the stock turbo). The only other reason I want to keep the turbo stock is I like to make sure I am challenged. To get 400hp on any turbo I want would be incredibly easy.

Please just let it go. I dont want you to get pissed or anyone else (Including myself).

Also, please let me know what the stock fuel pressure is

Ted B

iTrader: (6)

No one here is telling you that you're an idiot, but you are definitely going a ways toward alienating yourself by posting some rather pointed comments, which IMO is not exactly the best approach for someone seeking advice. There are varying degrees of expertise on this board, and you'll just have to sort it out for yourself like the rest of us.

Regarding FP, the design criteria is typically ~39-45psi and it rises proportionally to the manifold pressure to maintain that differential.

Ted B

iTrader: (6)

Actually, many persons don't know how the ECU works, and let's face it, this isn't exactly self-explanatory. What I am trying to tell you is the only way increasing FP will be effective is to do it only during open loop operation.

Now, as far as they all do it, to the best of my knowledge this is just not true. There are many persons in this forum who are making far more power than your target that have not touched the fuel pressure...and don't need to do so.

My philosophy has always been that if something is not an issue, then don't attempt to make one out of it. Others may not agree.

TrinaBabe

iTrader: (3)

Thank you for your help. Like I said before, I am sorry if I offended anyone or made anything think anything bad of me but when people tell me that by doing something will not do anything at all I will make sure they understand how it would do something. I figure it may bother them at first but at least now they know. I have been wrong and everyone has, it sucks to figure out you are wrong but when you do you learn from it. This post now helped anyone reading it know exactly how fuel pressure and the relation to injectors works to a degree. By the way... you should look up the dead time between different sized injectors. The smaller ones are MUCH quicker (Which obviously makes it MUCH easier to tune for non-WOT times and helps smooth out your curve the whole time). Usually when I post a question I am looking for someone with extensive knowledge of the question, I hate to be answered by people that saw it on a movie and this is how it works kinda crap. Thanks again for your help!

TrinaBabe

iTrader: (3)

There arent many people running 10 seconds passes on this forum.. at least I didn't think so. 400hp will not get you near a 10 second pass. I would rather overbuild a car as opposed to underbuild it. I would in best case scenerio have the turbo my limiting part. I will make use of everypart I put in the car, and if I don't, who cares... its $150, looks "bling" and you KNOW it will be better than it was and if you ever need it you got it. This is my opinion which is obviously different than yours and thats the good thing about cars... everyone can do it thier own way.

Just for the hell of it, show me a few examples of 10 second 4g63 powered vehicles that are using thier stock fuel pressure regulator Might as well keep the topic going right?

Ted B

iTrader: (6)

No worries. Discussions yield rewards of knowledge, pissing matches yield, well, **** everywhere.


Now, regarding injector duty cycle, it's easy to select an injector that is too large for an application, but there are those running around with 780cc units (and greater) that are not sacrificing much in the way of streetability...so long as everything is properly rescaled.

Ted B

iTrader: (6)

In that case, just perform a search for those with GT3037 and GT35 kits and you'll find dyno figures certainly capable of 10 second ETs and a list of mods to match. Aftermarket FPRs are not a necessity.

One important note you should make is what I am saying pertains to the factory ECU strategy, which is maintained via reflashes and piggyback computers. Standalone units used by Buschur and 'DSM Motorsports' may behave differently because they have very little adaptability. Therefore, what applies to one does not necessarily apply to the other.

Porsche518

iTrader: (5)

No he is gonna use the fpr to get around maxxed out injectors by raising the fuel pressure to some astronomical number

TrinaBabe

iTrader: (3)

Well Ted it seems we have come to a gret understanding. Everyone has thier own way to do everything which is perfect! I meant the 10 second class by people running 10's... not capable of it... big difference there

700cc injectors arent too bad but there is still a huge difference from the 660s.. once you get to 800+cc they get kinda bad but I wont be near there for a while.

Now on the other hand, It seems more people have come to bash on me Mr. Porsche man... oh well. And yes, If I get close to maxxing out my injectors I will raise the fuel pressure... it would be non-sense to do anything else. Oh well Flame on my friend!

BadazzCR

iTrader: (5)

1000cc injectors are overkill for the stock turbo, but I never planned on keeping the stock turbo. With the upgraded turbo on my car at full boost on race gas I was seeing injector duty cycles of 72% will not being anywhere close to maxed out. With the EMS you can afford to run bigger injectors and tune for them, IE: no reason to buy a smaller CC injector only to have an upgrade them later.

Edit: On the stock turbo with the 1000cc injectors my duty cycles where around 53-55%

VTECH8TR

iTrader: (70)

good luck on your Goal .