What size injectors should I be using?

[1bad92lx]

Mods are as follows:
8.5cr 306
Ported E7's
E or B cam
GT40 upper and lower
70mm throttle body
Paxton Novi 1000 6lbs boost
Built AOD with 4.10's


The car currently has stock injectors in it and I'm thinking that might be a little lean. I'm debating on putting a set of aluminum heads on it in the near future and I don't want to buy too big of an injector. I was going to go to 24's and still use the paxton fmu. Is this going to be ok?

 

[88 Fox GT]

24s or 30s, I would say.

 

[CRASH7772]

24's N/A and 30's forced induction and 255lph pump on either even though a 190lph would work on the N/A set-up.

 

[1bad92lx]

I've got a set of 24lb injectors with a 75mm ProM mass air meter that I might try. I'm wondering if I don't go with aluminum heads if the 24lb injectors will be enough. I'm driving the car now with the stock 19lbers in it and it drives real good and seems to have good power. I'm just scared that it might be a little lean on top end. I'm gonna pull some plugs tomorrow and see if they are white from being lean. I know the paxton supplied fuel control unit is supposed to boost the fuel pressure when it senses boost to compensate for the needed fuel. But I'm still scared that it might be somewhat lean. Anyone with a similar combo have any suggestions?

 

[bmo37]

30's and ditch the fmu

 

[1bad92lx]

So if I got rid of the fmu, then the car wouldn't have added fuel pressure under boost right? I thought that running the fmu helped you get good gas mileage while still delivering more fuel when needing it. I'm confused. Can someone please explain the pros and cons of using an fmu versus not using one.

thanks,

Matt

 

[Grn92LX]

Use a 42lb injector. You can grow into it and you can completly ditch the FMU. If your regulator is boost sensative it'll add 1psi for ever 1lb of boost. Don't settle for mediocrety put what is BETTER and will take you FARTHER. You already broke your 331 (not your fault) so if I were you I wouldn't wanna chance a lean isse and blowing up car #2

I'd hope your using a tuning device!

 

[5spd GT]

Only get 42lb injectors if you can get a dyno tune. If not get 30lb injectors because of the added boost. 24lbers would be almost perfect IMO N/A.

Good Luck!

(Go with the 30's)

 

[Matts89LX5.0]

Use a 42lb injector. You can grow into it and you can completly ditch the FMU. If your regulator is boost sensative it'll add 1psi for ever 1lb of boost. Don't settle for mediocrety put what is BETTER and will take you FARTHER. You already broke your 331 (not your fault) so if I were you I wouldn't wanna chance a lean isse and blowing up car #2

I'd hope your using a tuning device!

42# inj, get a tune...mike said it perfectly

 

[5spd GT]

42# inj, get a tune...mike said it perfectly

Do you live by him or something

 

[Grn92LX]

Mike said it perfectly

Do you expect anything less from me

David, yeah he's a friend of mine and he knows how I do it

 

[88GT17MA]

We need a sub forum, "Grn92lx vs 5spd gt." lol, everytime I see one of you disagree with eachother im like "oh great, here we go again" haha

Its all good info from the both of you though. Def. some good reading, for once.

I'd say the answer depends on your future plans.

 

[Grn92LX]

David's a good guy in my book. Just some internet disagreeing. Its not like we have real personal beef. That'd be stupid, since its only the internet

 

[5spd GT]

David's a good guy in my book. Just some internet disagreeing. Its not like we have real personal beef. That'd be stupid, since its only the internet

Exactly

We just have different ideas on things...it's all good "in my book" too...