rustylugnuts

I'm receiving conflicting information about using 24 lb injectors in my 89 - L98. Has anyone used them successfully? If so, what pressure is best? I was given a re-manufactured set of 1996-97 24 lb Delphi Multec LT1 injectors and need to get my car back on the road asap.

I appreciate it, rustylugnuts

TJM

First advice is to read the FIC sticky above, this is an expert on C4 Injectors.

I am not sure about the LT1 part? but I have a set of Bosch 24 lb in my '89. So this is not quite "Apples to Apples" .

The results may differ, as I have an adjustable regulator and run 40PSI , but also have TPS runners, modified Throttle body, tuned headers, and barely tolerable mufflers, and it is an " SUBSTANTIAL" improvement.

I would compare the performance to a stock C5 automatic car [ but more low end torque].

Injectors alone? I would guess there is some benefit. Again the LT1 part is not something i can speak too, ask FIC!!!


TJM

WW7

According to Jon of Fuel injection connection the 24# injectors are for the 300hp to 375hp engines. I believe the 85 Vette and all the Lt1 corvettes used the #24 lb injectors, but they are rather large for the other L98 engines. Im not saying they positively can't be used but they are not made for these motors unless they have had modifications to raise the hp. FIC sells sets of Bosch 3 injectors in the proper poundage both (new and rebuilt) for your 89, and this is a much better injector according to everyone on this site that has used them....WW

BADDUCK

They should work fine. Put in an adjustable FPR for fine tuning.

rustylugnuts

I have spoke to Jon by email, I haven't the funds to buy another set of injectors right now.

BADDUCK, what would be a good but inexpensive AFPR, that would be a direct fit without modifications. Also does this regulator come with a new diaphragm?

I appreciate everyones input, the more the better in helping a decision, please keep this alive.

rustylugnuts

RetiredSFC 97

It is best to use the 22 lb but they will work.

Yes the AFPR should come with the diaphram. But they ain't cheap. If you have the money for an AFPR you need to just go ahead and buy the 22 lb. IMO

Well I looked them up and you can get an AFPR for a c note. And you would save one c note. So go for it.

rustylugnuts

RetiredSFC 97, my 89 has 178,000 miles on the original injectors and fuel regulator. Whether I use the 24 lb injectors or not, the regulator needs to be replaced. So if I were to purchase the 22 lb injectors the cost would be double. So the difference in cost would be a fixed regulator vs. an adjustable, because I already have the 24 lb injectors.

rustylugnuts

Aardwolf

I had a set of the LT1 injectors like that in mine. I wouldn't say you would need the AFPR if you could edit the chip. Change the stock injector rate to the new one. That's what I did. Either way can work though.

RetiredSFC 97

I agree, that's what I said after I looked up the cost of the reg. I would get an AFPR and go for it. You should be OK. I have read of others using them.

Kool88vette

I installed Trickflow 24 lb. injectors in my L98 with an Accel adjustable fuel pressure regulator. I tried setting the pressure at every setting between 35 to 55. I couldn't get it perfect until I did a custom tune.

I did a few other mods too. So my L98 may not be a good comparison.

rustylugnuts

What is a custom tune? It already has a stage 3 Hypertech power chip, hi-po dual cats, K&N, and flowmasters. With a AFPR would that help run the 24 lb injectors without any further modifications, or re-programs?

Thanks guys,
rustylugnuts

cv67

Used Bosch II 24s on a stock 89 ran great. No datalogging so if it was "off"some and needed tuning I never would have known, sure it could have been improved.

Because it feels good doesnt mean its right.

rustylugnuts

Looks like the 24 lb are going into the 89. I will install a AFPR and I'm assuming 36 to 40 psi fuel pressure should put me in a good starting position, then will make one or two lbs changes if needed over the next 100 miles. Any other suggestions, before I get started, anything!

I want to thank all for your suggestions,

rustylugnuts

RetiredSFC 97

Come back and let us know how they work, if you would, for future reference!

rustylugnuts

Most definitely will, That's what this forum is all about..... Helping each other.

rustylugnuts

Kool88vette

With a custom tune your injectors will be fine tuned to fit your engine. They look at the blm, pulse rates, and a bunch of other stuff that I don't understand. The ecm controls all that stuff. The ecm is adjusted to accept the new injectors.

A custom tune, If done properly will mean optimum performance for your Vette. You should have a smooth idle and acceleration plus an increase in HP and better mileage.

Your Vette is basically stock so you should be able to get it running OK with an adjustable fuel pressure regulator. I did 1.6 RRs, Superam and a few other things.

cv67

imo alll you need is the stock FPR, cranking that around or timing isnt going to fine tune it as you dont know where its at to start . Talk to someone who knows tuning if its a concern and ask them the particulars.

Kool88vette

I removed the adjustable fuel pressure regulator and put the OEM unit back on. I just installed a new diaphragm on the stock regulator. Then I had it tuned. It starts in a split second and runs like new. A good tune is important when you make mods to the engine.

WW7

Even Jon says on his FIC site if your going to use 24# injectors in an L98 you will have to get your chip reprogramed for it to be right,and inless you hook it up to a scanner you may think its running ok, but your air/gas mixture can be way off, which can cause engine damage over time. Im a firm believer in using the right part, not putting in something thats close then having to compensate... Is all this really worth the trouble to use 24# injectors??? If you pay for a custom tune, plus an adjustable FPR its going to cost more than just buying the right injectors ....WW

Below is from FIC site...

Product Information

If your car came with anything but 24's the ECU will need recalibration

http://fuelinjectorconnection.com/sh...&productId=166

Vett-eight-nine

You will be running rich and your exhaust will smell.