bkpliskin

Hey guys. All mods are in my sig. I was considering going with 42# injectors but I want to make sure those won't be too big for my setup. I also plan on running nitrous, anywhere from a 75-125 shot. Also, what kind of benefits in terms of performance and reliability will I receive by going with a new MSD ignition?

'94 Bad A Z28

You could probably go with 30lb injectors and be fine, but I am no fuel guru. I have 36lb injectors in my 383 car and have no fuel issues.

n2ceptor

http://www.gtsparkplugs.com/InjectorSizeCalc.html This will give a ball park figure.. But adding nitrous, not sure....

bkpliskin

thanks for the link... it says I'll need 36lb injectors in order to stay at a maximum of 80% duty cycle. Would using 42#ers be too big in that case? I still plan on adding a few small mods to net myself about 15-20 extra hp (pulleys, ewp, ignition)and then I have to take the nitrous into consideration. The nitrous will be used sparingly. Maybe one or two track runs per year and only occasionally on the street when I run into one of the big boys.

WS6T3RROR

36lb will handle most street engines, it takes a bunch of hp to require a 42lb injector. I wouldn't go any larger than I needed, if you have an 80% duty cycle you have plenty of room for your other small mods. Keep in mind the brand and style of injector is every bit as important as having enough flow. A 36lb injector is not a 36lb injector some are way better than others.

Injuneer

My guideline for minimum injector size is to multiply the FLYWHEEL HP by 0.07. Example:

500HP x 0.07 = 35 #/HR

That assumes you don't want to exceed 85% DC and have a tune that will achieve at least an 0.476 #/HR/HP BSFC. Those are both reasonable assumptions. The online injector sizing programs are overly conservative with respect to DC and BSFC.

Going larger does not hurt you, as long as the PCM can turn the injector pulse width down low enough to allow the engine to idle smoothly. The stock PCM seems to be able to handle 42 #/HR injectors with no problems.

With regard to the nitrous, you have to tell us if its a wet or dry system. A wet system doesn't flow the extra fuel through the injectors, so it has no affect on the sizing. A dry system flows the extra fuel through the injectors, but typically raises the fuel pressure when you are spraying, to provide the extra fuel without using a larger injector.

bkpliskin

I'll be running a wet kit with 75hp jets on the street and 125hp jets at the track. I know the wet kit has it's own fuel solenoid but I wasn't sure if the PCM does anything to compensate for the whats going on in the engine while spraying. I appreciate everyones help, you guys have been very helpful over the past few years with my questions. Also, I've got a general question about my bottom end. It's a 2-bolt, completely stock. Stock rods, pistons, block, rod bolts, piston rings, everything is completely untouched. I currently have the 1-2 shift set at 6250rpm and then decreased 50rpms each shift after that. This was recommended by Bryan an PCMforless when I stopped by his place for my tune due to having a bone stock bottom end. (he said he had issues with his CC306 LT1 once he hit 6300 with stock rod bolts) Should I back it down a little and will my bottom end be able to hold roughly 600hp when I'm spraying the nitrous? I've been working on this for a couple years now and have only been able to drive the car 40 miles since June 2007 due to certain issues. (each issue has been the reason for further modification which I think will ultimately be well worth the wait)

bkpliskin

I'm looking for some 36#ers as we speak. What brands would you guys recommend?

bkpliskin

anyone?

'94 Bad A Z28

Man you only asked not even an hour ago... give people some time.


I am running SVO injectors.

Injuneer

Please read the "sticky" at the top of the LT1 forum topic listing regarding "abuse of TTT".

bkpliskin

sorry about that guys... it just seemed like we were having almost an instant messaging session there for a while and then about an hour went by without a response but I saw that you guys were still posting responses to a couple other threads in that time span and I was prepared to place an order before I went to bed tonight so I could get things rolling on the mods by the beginning of next week so everything else is done and ready when I order the tranny.... There have been many occasions that once my thread drops down to about 10th on the list of recent threads that it never gets another look/response.

I was unaware this was abuse or a breach in the threads rules/regs. I'll make sure not unnecessarily bump my threads in the future. I apologize for the inconvenience.

Thanks again for your help guys.

Injuneer

A lot of people opt for the Ford/SVO/FMS/Bosch/Denso pintle style injectors, because they are relatively cheap. I run Bosch injectors, but they are 9 years old, are low impedance, 64 #/HR, so my experieince isn't relevant to your question. But Bosch has a new design for their injectors that looks pretty interesting. I've seen posts by more that a few people who have had problems with the Accel injectors. FAST now makes a very interesting injector, but I haven't seen anyone using them yet.

Look at what is available on the Ractronix site. I think their instructions and tech support may be a little weak, but they do sell injectors specifically for the LT1.

WS6T3RROR

My recommendation is the bosch design 3 injectors. You can tell them by their 'skinny' looking body. The white fast 36lb injectors are this design and I have been using them on stuff for a few years now with great success. This design can be bought any number of places though, fuel injector connection probably is the easiest/cheapest place to get them in various sizes. I also think the ford svo injectors have changed to this design as well.

rskrause

All the brands seem to work ok until you get to very high fuel pressure.

Rich