So I'm building my 1le's L98 up since winter is here (northern fricken Vermont!) and am looking at 42 lb Holley injectors for my TPI. I just got in SLP runners but will stay with the stock upper plenum and heads for now. If I burn my own prom for 42lb injectors (1) is 42 lbs alright and (2) can I remove ATI's' FMU? I'm running 9lb pulleys I believe on my P1SC

 

42's are huge, then again thats what ford uses on the lightnings, andthey are not huge motors but do make decent boost.

 

I guess I really want to know is if I get a decent deal on these (which I will) is 42lb injectors, stock L98 intank pump and ATI's inline pump going to work? I realize I will have to reprogram the prom. Also, can I nix the FMU?

 

Sounds like these are some large injectors for your boost level. Also, it will be difficult to get these tuned for normal driving and for boost conditions.

You need to read some posts on the 749 ECM which can read boost and adjusts the fuel intake accordingly. However, even with this computer the injectors will probably be too much.

Talk to rooster433. He worked with me on my boosted set up.

 

A tad large considering the Syclones made 14 PSI and used 30s.
Yes, the last thing you want to risk an engine on is a FMU.

Personally, I'd rather run a lil too large of injector then be caught with too little of injector.

I'm running the equivalent of 60s in my little 231, so I don't see where you'd have any problem with 42s.

 

From what I understand, AC will need more than a reprogrammed prom to handle the larger injectors, though.

What alternatives do you recommend that he can use to eliminate the FMU?

My experience is to go with the 749 ECM set up or a superfueler like Willie has used. However, he is currently planning on going to the new ECM set up too.

 

I swear almost all mustang guys go for 42 Ib injectors when upgrading there boosted little 302's, now I'am sure if these guys can do it with there stock computers and matching MAF meters then we could do it with are fine tuning of are proms.

 

I use 55's on my 9lb boosted combo. should be good for 700 hp @the crank. But I use a dfi.

 

The 749 has some code in it to switch to quasi if the injector pulse widths get too low. This makes me feel that the 42# would work ok.

-- Joe

 

Hmm, I thought it was asynch.

Anyway, I'm running 60 PPH injectors on my lil v6, with a 749.

 

The hack said Quasi. But I dunno.. I havn't really looked at the code much. I work in C all day long, and then I go home and tinker with the car and assembly just makes me sick..

-- Joe

 

I'm calibrating a ZZ4 right now with 42pph "green"/Bosch/Ford Lightning injectors. Pulsewidths get a little low, but they are consistant enough. I know the ZZ4 doesn't need these, 30's would be fine, but this is for a company project, and I'll be switching it to 30's soon, and checking the calibration with a multiplier.

I second the notion that it goes to Quasi-synch with small PWs - injects once per intake stroke, rather than twice.

42s should be safe to 500+ HP with a high BSFC. So, they could stay with the engine with mods up the yang.

 

I may not be able to convert right...but DSM's run 450cc injectors on their stock engines(2.0) and that converts to around 42lbs. And they only boost 10psi from the factory.

The ford 2.3t That I built for a friend got 55lb injectors, and it runs fine at low boost (stock 10psi) med boost (18psi) and high boost (25psi)

on the other hand, me and my uncle used some 44 lb mopar injectors on his c4 with a vortech, and we pulled those very fast and put in ford *edit*brown tops (35lb). afr was like 10:1 on the wideband before dropping the injector size.

 

91rsklown - was that with tuning for the injectors or was that just sticking big injectors in it and hoping the ecm figures it out?

Someone care to explain quasi vs asynch? From the discussion it sounds like "normal" or synch is once per revolution (2x per power stroke), quasi is once per power stroke and asynch is not synchronized with anything?

 

Crossfire read the turbo P4 document it will explain the use of diff. injector firing modes which is applicable to the $58 setup.

 

Huh, no ****… someone actually gave me some useful GM ECM info (usually it's either a complete BS guess or "read the ___" without actually specifying what ___ is).

Thanks Yenko... :hail: (I don't think that I've ever used that smilie before, generally I think it's kinda stupid, but for once appropriate). Wanna point me at anything else useful along those lines while you're at it?

 

First, everything that I know about injectors is based on my work with turbo Buicks and the stock 1227148 ECM

42# injectors are not really that big and should work fine as long as you are burning your own proms or are working closely with your prom burner, they are high z so they'll work fine with stock injector harness/drivers - and they should support aprox 670hp on a V8 at 100% duty cycle(they are good for about 500 on a V6 at 100%). On turbo buicks they sometimes give minor driveability and spoolup problems (too rich in lower rpm's) and they have been giving chip burners problems for years.

If I were selecting injectors for a high power V8 I'd go with the MSD/Delphi 50# injectors which have proven to be very linear aqnd work well on turbo buicks from bone stock cars all the way to aprox 600hp at 100% duty cycle. They should be able to support 800hp on a V8 at 100%(and 640hp at 80% duty cycle for those wanting to stay on the safe side).And they are high z so again no injector harness/driver modifications needed.

I'm of the opinion you can never have too much injector as long as you tune for them and what your motor needs.Last year I was running my 55# low z injectors at 100% which was limiting me to about 650hp, or about 50-75hp short of what this motor should make.While I know 72# injectors would probrobly be all I need to get there I went with 83# injectors instead and the only problem I've had is having to raise the idle up to about 850-900 from 750rpm with the 55# due to instability at very low pw.

HTH,
Steve

 

Actually that is about the only doc I have found that is supposedly strait from GM. It makes tuning with the $58 a breeze, and it really helps one to figure out what the ecm is doing without looking at hacks.

 

the 2.3t was tuned with eec tuner, wb02, and has an egt on it all the time. The vette we used just a wb02