Changing engine

[Seagull81]

I have been thinking about changing my 302 (19 lb injectors) for a 347 (24 Lb. injectors). I was wondering if I have to change to another computer or buy an aftermarket chip.
Thanks,
Steve

[cwhoofgator]

Originally Posted by Seagull81

I have been thinking about changing my 302 (19 lb injectors) for a 347 (24 Lb. injectors). I was wondering if I have to change to another computer or buy an aftermarket chip.
Thanks,
Steve

Need more info on set up. I have 24lb on my 306 so I am sure you would need more inj. What is your ECU?

[Seagull81]

My 302, harness and computer came out of an'89 Mustang. The guy I am talking to about the engine has some 35 lb. injectors he would sell with it, but I wasn't sure if I needed them or if my 24 lb. injectors would do.

[cwhoofgator]

Yes take him up on it for sure,what TB do you plan on using? ECU is fine but should get a tune.. OH fuel pump needs to be up-graded to, never ends...

[Seagull81]

I have a 70MM TB right now and I'm thinking I need a 155 pump.

[Bob Cowan]

With a stock computer, 24# injectors are good to around 300 or so HP. I would expect a good 347 to make considerably more power than that. 35# injectors should be good to about 450hp, with a stock computer.

I would expect you would need a new tune with the new engine. If you're upgrading, you'll probably use a "bigger" camshaft, bigger heads, and more compression. Your current tune will be fairly with your bigger injectors. But it will only be fairly close.

A custom engine needs a custom tune. There's no off the shelf or out of the can tune that will work for you. If you want to get the most from that new expensive engine - and you want it to last - pony up the bucks for a dyno tune at a good shop.

[AC Bill]

Might have to upgrade the tranny too.. like he say's it never ends..

[JKleiner]

You can keep the stock A9L ECU if you use a MAF matched to the injectors.

Jeff

[UrQ]

We are running the Trickflow topend package (stage 1 cam, upper/lower intake, heads) with RWHP in the ~330HP range and run stock A9L computer, 24lb injectors with MAF to match and 70MM TB. You will need a variable fuel pressure regulator.

[turbodon]

Steve

It all depends on a lot of variables.

Are they 24 lb 3 bar injectors or 24 lb 4 bar injectors?

24 lb 3 bar (45 psi) will run 29 lbs at 4 bars (60 psi) pressure. Hence adjustable regulator and fuel pump rated to 60 psi.

24 lb (45 psi) will be maxed at 100% duty cycle @ 430 HP.

Upping the fuel pressure to 60 psi gives you a 20% margin. This will allow injectors to operate at 80% duty cycle Max. Much better...

32 lb 3 bar injectors would need to have the fuel pressure dropped to maybe 30 if a low HP 347 build.

So as cwhoofgator mentioned "Need more info on set up."

Time on a steady state Dyno and chip curve matching will be required? Depends on a lot of variables.

Maybe a stock cam and heads on a 347 with 24 lb injectors would run with a stock computer tune and a special MAF. Other than that Chip re-curve.

[Seagull81]

Crap! The guy sold it out from under me today. But I'm still going to buy a 347, so all this info. helps in my decision making and parts gathering.
Thanks, guys.