i have a 355 sbc going to make about 430hp, cam is 224/230 dur 112 ls, 9:1 compression, headers, world products 200cc sportsman II w/ 64cc chambers.
i'm purchasing a used HSR with adjustable fuel pressure and twin 58mm throttle body. It comes with 42# injectors, will these work with my current setup if i turn the fuel pressure down some? because i want to allow for expansion also.

 

I think they are too big. I'd look at 36s. That will give you room. 42s are good for close to 600 HP. YOu have a long way to go to get there.

 

Your going to have to burn a chip for the new combo anyways so you might as well use them.

 

you need 24-27max on that. stock for a TPI 360 is 22lb. /When they're way too big like that you can/will run into trouble getting it to idle right as the computer will have trouble sending a short enough pulse at idle.

The heads are way too big for 355 size and cam you've got.

 

The issue is getting the tune at idle, those injectors are a bit hard to control, they are low impedance.

 

There's no such thing as a 27# injector, we were recently through that.

430 HP would require 30 lbs. 36 if he wants room to grow.

 

Until he actually tries them you can't say there will be a issue, there are lot of cars running around with 42Ibs or bigger without problems. I'am using 60Ibs at the moment and idles good, if that myth was true I would be having a hell of a time right now.

 

There are plenty of 42# injectors that are high impedance.

 

OOPS you're right, they are high impedance. My mistake. Typo. In fact, it's what I have in my car.

I meant they are hard to control because they are HIGH impedance.

Low impedance injectors are a bit easier to tune for idle.

 

Are those 60s low impedance? Probably Seimans right? Yes, they are easier to control at idle.

I agree, for the most part, the issue is these old style 42s aren't so easy to tune. You have a better injector. The Bosch III design are a bit better, but I am assuming since they are hard to come by, he's running the older style, they are far more common.

I aslo agree there's a lot of cars running around with 42s or bigger, that's a bulk of my business. 160s, 220s, 80s, 90s, etc... But those are different builds, not his. We're talking a relatively mild 355.

 

High impedance, would have fried the computer long ago if it was the other way around.

Yes it's a mild build but might as well use what you got.

 

I wouldnt say they are that big if he could bump his compression up he will be in good shape and will allow room to grow. there is a guy on here running the xfi 268 and 195 and an hsr putting down 350 at the wheels, he has a bigger cam so....

 

the cam i'm using is an xtreme energy 276hr hydraulic roller 224/230 duration at .050 and i remembered wrong its 110 ls

 

I would knock them down to 30s IMO. I'll give you something back on the 42s if you want, PM me and we'll work something out. I'll do a set of 30s rebuilt and credit for the 42 cores, assuming they are good.

 

I agree to use them if they are coming with the intake. My 350 is even milder and idles fine with 60lb injectors. Just get the tune right and you'll be fine.

 

You have a turbo, not the same thing.

Yes, if you have a good tuner and can work around it, they will work. I'm just saying sometimes it can be a bitch with a high impedance injector.

 

My fuel requirements at idle and cruise is less than what the OP's engine will need, so being turbocharged is irrelevant when debating whether an injector will be too large to tune around.

 

42 lb / hr would probably work well for a flex fuel or E85 application. I'm getting ready to replace my injectors on my 331 with 36 lb /hr ones to be able to feed enough E85, and still be able to de-tune them for plus unleaded. I'm running a Megasquirt I so I can directly control the pulsewidth and fuel required. Once I upgrade to the Megasquirt II daughter card, a computer controlled distributor, a wide band O2 sensor, and install a GM flex fuel sensor it will be self-tuning and on-the-fly flex fuel capable. I already have an MSD 2225 high volume pump, and a tank and lines rated for ethanol, plus the computer controlled HEI that came with my TPI setup.