Does anyone know how much power the stock fuel system can support? With larger 440cc injectors. Thanks.

 

Well there are limits, and there is safety. I would say limits would be mid to high 300whp range. Anything above that should a return fuel system kit installed. Its better to be safe than sorry, even if your goal is a 400whp car. Also makes tunning much easier and more reliable. Hope this helps!

-George
GT Motorsports

 

Do you think it would be safe to run a Vortech on the stock fuel system and larger injectors. This way, I can get rid of the Vortech FMU and not have the high fuel pressure at idle associated with the Walboro. I will definitely be under 400whp, more like 360whp at the most.

 

Hmm, hard to say. It all boils down to your budget and how safe you want to be. I can tell you that the best/most cost effective way to run a return fuel system with the walbro, and the 440CC injectors. This way you will have a nice stable fuel pressure at idle and throughout the RPM range. Let me know if there is anything I can help you with.

-George
GT Motorsports

 

Well, with the Walboro, I'm going to have a high 80psi fuel pressure which will kill my gas mileage. Is there any way I can take the Fuel Pressure Regulator from the CJM or AAM Fuel Return System and add it to the stock fuel system?

 

I have the set up you refer to and mileage is controlled by your A/F ratio which you should control by reflash for the larger inj's and tuning it to around 11.5 / 11.8...

 

Do you have the high fuel pressure idle problem? What's your gas mileage? Have you checked you FP after the install? This high fuel pressure is caused by the Walboro flowing too well at idle, but when the car goes WOT, it comes back down to normal.

 

Normal driving and idle the FP is around 80psi...At boost the FP initially drops some and when the FMU/Aux FP comes on it rises above 80 psi as it should..As to mileage I dont check it since the car is for fun and pleasure AND not a DD.. I would guess its around 20 mpg..

 

That's going to be a problem for me because my car is a DD. Normal idle fuel pressure is 52psi, so I am trying to keep it there. As a reputable tuner suggested to me, I could just go with 440cc injectors and dump the Vortech Fuel System and stick to the stock system. With under 400whp, the stock system should be able to handle it and be more reliable then the Vortech fuel "booster" system. This would solve my dilemma with the high idle FP and then I would not have to opt for the $1k return fuel system. I just wanted to confirm this information with other knowlegeable FI people.

 

Couple thoughts: With my FP dropping at boost and coming back up with the FMU/Aux pump I am not sure the Walbro and 440 will be sufficient w/o the FMU/Aux pump...A return system in my humble opinion is an overkill for our set ups...Whatever you do you should plan on a dyno tune and make sure the A/F is sufficient.. Be a guinea pig and let us all know if it works.. Thanks

 

Haha, ok. Of course I have to retune. But if it doesn't work, I will be out a decent amount of $$$ on the labor and retune. Just wanted to make sure this was possible to do. So, are you running 440's, Walboro and the Vortech fuel system(aux bosch pump and fuel booster) all together?

 

Yep...

 

That really doesn't make sense. You can get rid of your Vortech Fuel Booster parts and have a much more consistent A/F without it. The Walboro makes the Vortech fuel stuff unnecessary.

 

Please re read what I said earlier.. The FP drops and recovers with the FMU..Try it and report back..

 

The fuel pressure is suppose to drop in the 50's when you get on the gas. I believe, it should be in the 50's at idle and WOT. Someone correct me if I am wrong.

I mean, the whole point of people with Vortech's going with larger injectors and aftermarket fuel pump is to get rid of the Vortech supplied fuel system, since it is unreliable and inconsistent.

 

Bump on this. I am hearing conflicting reports on the stock fuel pump limits. Some say 360whp and some say 400whp, both with first hand experience. How can it differ so much?

 

fuel pump capacity can depend on a lot of the fuel system. for example, if all your lines and rails are nice and free flowing, the pumps capacity will actually go up a little. If your running all stock stuff, it will be at its lowest.

basically when running things on the edge, you will find inconsistencies that can greatly vary based on small changes in conditions.

 

This has been on my mind as well. I've got the Vortech kit with the fuel regulator and booster pump, but I am switching to 440cc injectors. Do I need a replacement in tank fuel pump or will their booster pump do the trick? Can I scrap the vortech fuel system (which seems shoddy to me) and just put a bigger in tank pump in with the stock lines? Is fuel pressure with a bigger pump and 440cc injectors enough to support 400whp? Also, will I need a reflash to make the injectors work right or can it be tuned to work using the SS box? Lots of questions sorry.

 

how much hp can 440cc + intank walbro with return line hold up to?

 

400rwhp or so.