lbs/hr to cc's

[Redline240]

Can someone give me the formula for converting metric injectors to imperial? Or even suggest eqivalents, like 370cc are close to 52lbs/hr, etc...

Redline

[Jeff240sx]

Divide by 10.5 . 370cc/10.5 is around 35#/hr. 50# injectors = 525cc. -Jeff

[TrunkMonkey]

cc / 10.5 = lbs/hr

or

lbs/hr x 10.5 = cc

-demetrius

[Redline240]

Ok, see if you can help me out with my math here. I'm goin to use a hacked maf and safc, along with a mustang fuel rail(if it fits) and some 50lbs/hr(or close to it) injectors. The maf will run with 370cc(35lbs/hr) injectors with little adjustment to the safc. So 50lbs/hr injectors are 30% larger than 35lbs/hr injectors so if i set my safc around +30% it should be somewhat close right? Of course i'm goin to tune this with a wideband but i wanna be sure i have plenty of room to compensate with the safc. Now, i'm probaly missing something so please tell me whats wrong with my theory...

Redline

[huguetpj]

50# injectors are around 525cc as someone said. So, if I'm not mistaken:

(525-270)/525 = .48 ~ -50%

So u should be able to compensate with the SAFC.

[Redline240]

Thats why i want to use the hacked maf, which would mean the ecu would think 370cc injectors are 270's. So it would be;

(525-370)/525 = 0.29 ~ 30%

Redline

[huguetpj]

Yes

[Def]

Your maths are wrong...

For a stock ECU + 370cc inj you want a MAF diameter of 37% larger in theory(in practice people have found this is lean, searching yields more info).

Maths (370cc = new size, 270cc = size ECU is tuned for)-

(370-270)/270 = ~34%

You would want to then make small adjustments to the AFC to fine tune the A/F curve after using a wideband O2 on a dyno or street test.

You seem a little confused on what a Hacked MAF actually is, so some searching would help you plan this out some more(it has to do with changing the cross sectional area of the MAF instead of tuning straight off with an AFC device). I suppose you could straight tune with an S-AFC, but it would be more difficult as you are using fuel and ignition tables farther and farther from the "actual" conditions represented in the ECU which adds in a bit more of a "fudge factor" compared to the Hacked MAF setup(which isn't even that spot on in the first place...).

Feel free to correct me if any of my info is wrong, but this is a "hacked MAF" as I understand it, and I hope I can do simple algebra with all the freakin' math courses I've had in my days.

[huguetpj]

What he wants to do, or at least what I understood, is run 550cc injectors with a 370cc injector hacked MAF... so our math is ok (I think :pface ) since instead of having to adjust the AFC by -48% he just needs -30%.

[Redline240]

What he wants to do, or at least what I understood, is run 550cc injectors with a 370cc injector hacked MAF... so our math is ok (I think :pface ) since instead of having to adjust the AFC by -48% he just needs -30%.

You got it! I don't want to max out my safc, say if i needed -51% i'm screwed...so the hacked maf gets me in the 30's and i have tons of room to play with!

Redline

[huguetpj]

I don't thik you'll need to used any setting near the +-50% mark, cause my friends turbo eclipse is using 660cc injectors with the SAFC (I believe stock are 320cc or something like that)

(660-320)/660 = 51%

And I can tell ya the lowest setting is like -30/40% at idle. This is tuning using the EGTs, still haven't taken it to the dyno. Anything lower than -30/40% would increase EGTs a bit too much when cruising.

[Def]

Oh gotcha - that seems a weird way to do it though. Why not put the MAF in a slightly larger tube to have to correct less with the S-AFC? It would be a more elegant "ghetto" solution if that makes any sense.

Seems like you're taking one step forward and two steps back with your proposed plan.

[Redline240]

Oh gotcha - that seems a weird way to do it though. Why not put the MAF in a slightly larger tube to have to correct less with the S-AFC? It would be a more elegant "ghetto" solution if that makes any sense.

Seems like you're taking one step forward and two steps back with your proposed plan.

I didn't mean to seem ghetto, so i'll explain. I'm goin to be mounting my intercooler and rad as a v-mount setup. This will give me enough room to run 3" intercooler piping. I'm making a aluminum intake manifold and mating a Q45 90mm throttle body to it. So every part of my setup will be 3" or bigger so unless i hack the maf to make it 3" it'll be a bottle neck...eventually i'd like to replace it all with a stand alone and map sensor but thats a long way off...

Redline

[huguetpj]

So every part of my setup will be 3" or bigger so unless i hack the maf to make it 3" it'll be a bottle neck...eventually i'd like to replace it all with a stand alone and map sensor but thats a long way off...

Now you're plan makes sense :pface

By the way, stock 1g turbo eclipse injectors are 440 so:

(660-440)/660=33%

So I withdraw my previous statement. 550cc injectors in a 240sx with a SAFC is working on the edge. But I believe somebody has already done it, so it should work.

[Redline240]

Now you're plan makes sense :pface

By the way, stock 1g turbo eclipse injectors are 440 so:

(660-440)/660=33%

So I withdraw my previous statement. 550cc injectors in a 240sx with a SAFC is working on the edge. But I believe somebody has already done it, so it should work.

Yeah i could use dsm injectors too since they'll handle over 300hp on a KA and can be had pretty cheap. Are they top feed?

Redline

[huguetpj]

Are they top feed?

Yep. Someone here was talking about using EVO injectors which are bigger. I would go with the 550s anyway, to have ample growing space. Actually I've already have them... need to revive my beast and have a custom fuel rail made.

[Def]

I'm pretty sure the MAF hacked to work with 370cc's is less than 3" ID. Something like 2.6" give or take.

Or am I remembering this wrong.

[huguetpj]

I'm pretty sure the MAF hacked to work with 370cc's is less than 3" ID. Something like 2.6" give or take.

Or am I remembering this wrong.

2.75" or 2.8" if I remember correctly. It's somewhere on the forum, searching would help.