The only problem i see with this is running larger injectors than are actually needed is potential drivability issues. I would think that running say a 750cc injector would cause drivability issues on stock block cars because most people who are running a stock block would be running something along the lines of a utec. This is all based on my understanding that the utec has trouble running injectors larger than 650cc.

Not saying I disagree with you Jeremey, just pointing out something I see as a potential problem. Hell i hope i'm wrong because i know i would like to save that 1 grand.

 

Now thats how we roll!!

 

My tuner runs 750cc injectors with the utec. i'll be using their base map to break in my engine. they spent quite a few hours on the tuning aspect trying to get the drivability 'just right'. heres the link to their buildup.

http://www.carv2.com/site/project_detail.cfm?id=247

 

I still haven't fully grasped the concept of a return fuel system and why or when it's needed

 

Is there any easy, proven way to raise fuel pressure on the stock system with walboro?

 

I've been running RC550cc injectors with no fuel return with absolutely 0 issues. I'm glad I saved that $1000 plus install. Now that money will be going to my new clutch/flywheel setup.

 

Great job Jeremy . I love an honest vendor !!!!!

 

+1

I have never do any bussines with Jeremy, but I talked to him on the phone and I can tell that he is a honest person. I am glad that I have people like him and Roger (JAPTRIX) in Florida. Honest vendors are in extinction!

Cesar
Orlando Fl

 

you'd have to remove the stock reg. in the tank and put one of CJ's pieces in there. Then you'd have to hook up some sort or external reg. (aeromotive, etc.)

 

I must say you are talking a big risk. We have logged fuel pressure without RFS's, and the trend on each pull on the dyno is slightly different. You are replying on an electric pump to maintain your dropping fuel pressure trend....rather than a mechanical FPR, raising fuel pressure 1:1. There is no way I would do an engine build without an RFS, IMHO.

In addition, with larger injectors you will experience 70psi plus fuel pressure at idle, which makes getting a clean start and idle very challenging with 750cc injectors. Sure, you can drill out the fuel pump housing as TN suggests with their kit, but its still a guess, basically. I could see doing this with 440cc-550cc injectors and low boost (5-7psi), but not with high boost on built engines.

When we build cars, our #1 goal is reliabilty and consistency. Making some good dyno numbers is not enough. We want a customer car to run consistently from day to day, and last a very long time.

I admire your desire to try new things, but this is not a good idea.

Edit, i see you are just suggesting this on stock blocks.....but stock blocks require even MORE due dilegence to keep them in one piece.

 

I've been saying this for a long time now... but then again what do I know?

Sure a fuel return line makes it EASIER, but it's in no way required.

 

Another less expensive option, is to use the AAM mini return fuel system which is $499 instead of $999. It seems that the majority of people that go FI, eventually intend to build the motors, making an RFS of some kind, a pretty good idea.

 

Subscribing!

This is the situation I am in currently. I have a TN kit with 440cc, looking for 400Whp, That $1000 return is really holding me back. I am leaning to the side of safety because $1k is much cheaper than a new motor.

 

JT, do you do the Turbonetics Walbro install steps like drilling out the factor FPR and drilling the three large holes in the plastic surge tank?

 

I really would like to know what this whole safety thing is concerning a RFS

 

I am not debating your claims, but if a $1K RFS if delaying the install of someones ST or TT kit because they can't come up with the money then they really shouldn't be going FI. Chit happens and motors go boom. If they don't have $1000 for a RFS then they certainly won't have the $5K to rebuild the blown motor or even replace it with another stock motor. Also if they don't have $1K for a RFS I am willing to bet they don't own a beater or can't afford to buy one when the stock motor goes.

 

Really the only thing you loose with out a RFS is the 1:1 rising rate of fuel pressure. For example if your fuel pressure is 50psi base and you run 10lbs of boost your fuel pressure at the injector nozzle is reduced by the manifold pressure of 10psi. So at 10psi boost your working with 40psi of fuel pressure not 50psi, and thats enough pressure to work with and do a proper tune for sure. Even at part throttle say 5psi of boost you can tune for 45psi. Sure the fuel pressure not being a fixed variable makes the tuning a bit more involved, but we aren't landing on Mars here.

 

I am not sure on the details, I have researched that a few times, it always comes back to "You Need It to keep the motor intact"

I do know that on aircraft engine, the fuel returns regulate pres. and alleviate excess in the fuel distribution.

I am assuming it is something along those same lines.

-Don

I may really look into the AAM mini return.

 

Well, not exactly. If you simply drop a Walbro into your fuel pump assembly, two things happen:
1) Fuel pressure and idle and cruise will be 70-80psi. The TN fix drops the pressure down to about 52psi, from what we've seen.

2) Fuel pressure under boost actually drops, and it drops by varying amounts. Some cars, we've seen drops of just 5psi, and others have dropped 20psi. Without the TN fix, the pressure drops like a brick...down to 30psi by redline at 8psi boost pressure.

So your differential fuel pressure is even lower.
All these unkowns and changes result in inconsistencies in the tune.

 

^+1 without a fuel return or some sort of FPR in your system tuning willbe tough specially anything over 8 psi, it can get tuned but it wont be consistent.