my car had a bad vibration around 2000 rpm and it turned out to be three bad injectors so i replaced the three and it still has a slite vibration at 2000 rpm. So now ive decided to replace all of them with new bigger injectors. What size do i need? I do have a AFPR and a 255 walbro hp pump. Thanks

 

It would either be 24 or 30 depending on how much hp you are pushing. I believe 30's will handle 500hp max.

 

Also what size of injector will require me to change my prom? Ive read that you can adjust ur fuel pressure for the time being, until you get a different prom.

 

I believe the formula is :
lbs/hr x 16 = horse power output

Depends what you have done, but too much of a good thing can be bad. Although being rich results in lower combustion chamber temperatures it also results in poor fuel economy. Go with 24 or 26 if you can find them. Some people (including me) have high rating fuel injectors but only because we can turn down the duty cycle on them and then turn them back up on the fly.

 

Tibo: Thanks for the formula. I was trying to remember it.

white91Z28: You car is speed density correct? The prom wont take much of any adjustment in injector size. Speed density is not partial to changes like MAF is. Adjusting FP is a temporary fix.

 

if you havn't gotten a custom prom done yet... now's the time. you pretty much need it if you have all those mods and are still running the stock one, you should PM 1bad91z, he did mine he knows wut he's doing, i trust him. you'll see a REAL difference with a new prom if you're still running the stock ecm

 

If he knows what he is doing then why doesn't he even know what to use for an '87 Vette? I can post tons more just like it. Learn how to do it yourself. The people who really know what they are doing are rare.

https://www.thirdgen.org/techbb2/sho...hreadid=226722

Tim

 

Ive been thinking about getting the ones on this site
http://www.slponline.com/view_produc...RTNUMBER=23051
Are these good?

Ill probably do my own prom buring too.

 

yeah, they're good... i was going to go with the slp/bosch ones for $99 but i found a deal on 24# svo's for $150 on ebay and went with those since i trust svo's more than bosch

 

Ahh, I see where this is coming from now.

First, I would like to say that I'm NOT a personal mail order chip company. I have helped a couple of people from time to time.

I don't advertise nor want anyone to advertise for me to tune PROM's.

If you need help tuning related or anything at all car trouble related, feel free to PM (send me a Private Message) or e-mail me at:

ms1badz@yahoo.com

I'm always willing to help someone unlike some people here. (I'm not naming any names or defamating anyone).

Mike (1bad91Z)

 

Unless your carring alot of liability insurance, ie a Million Plus Umbrella Policy, you really might rethink that. Friends are friends and buds are buds up until an accident or a grenaded engine.

Never mind now having admitted publicly, now someone can raise cane with your utility companies, and that can be all sorts of grief.

If you want to do them for anyone, do it legally. Other wise you can lose everything. Just resently a guy spent $25K to fight a lawsuit brought by some real yahoo (not about a chip per se, but close enough for the purpose of this posting). There was no way the clown was going to win, but he had a lawyer on retainer, and just wanted to make life miserable for a small business man. It really hurt the guy.

 

I did not publicly admit anything.

I HAVE helped some friends tune their car. Just like I'm sure you and many others have helped friends with their cars.

Like I said, I'm NOT in business.

I hope this clears things up.


Sorry to the original poster of this thread.

To offer some advice, use a complete new set of 24 lb. SVO injectors (dont just replace the ones you think are bad). This will hopefully eliminate the mechanical worry's (bad injectors). Then tune your PROM for the bigger injectors. If PROM tuning is out of the question, you can always adjust your fuel pressure regulator down to about 39 PSI at idle (with vaccum line off). This will help, but will not be as good as a properly tuned PROM.

 

I will agree with 1bad91z on the subject. He is just trying to help some people out, because we are all here to learn. I know about ECM/PROMs and the troubles they can give a newer person. If he is willing to lend a helping hand instead of just saying "learn it on your own buddy" He is doing a good thing.

 

Does anybody else like bosch injectors? Or should i go with a diff. brand.

 

Yea, of course. Just ask him how much help I have given him. I help anyone who asks me for help. I've taught many people how to do it themselves. I never say "learn it on your own buddy". The problem is when newbs then try to make a buck off of it. That just doesn't float ... especially when they then try to use the PROM forum as their tech support. They get the cold shoulder pretty quickly. I've said it before and I'll say it again: "If you're into programming PROMs for money then bye bye". Most people on the forum are more than willing to help teach people how to do it. You are never on your own. You just need to take the initiative and e-mail and talk to people. Heck - that's how 1bad91z learned. There's nothing wrong with helping people. But, there is a 'situation' when you use other people's hard work to make a quick buck.

Tim

 

I'm just thankful to guys like Trax and Grumpy for the research and information they have posted. These guys sure make it interesting for those of us who don't have the time to invest but would still like to work with the BLACK ART of chip modifying and programming. Please guys keep it up, we have so much to learn.:hail: :hail: :hail:

 

I have learned alot from people like Traxion, Grumpy, and MANY others here on this site. I've also learned alot by doing things myself.

And like I said, I'm not trying to make "a quick buck".

Leave this poor guy's (white91Z28) post alone. He has a question about injectors. If you have a question for me or a problem with me, then PM me. No need to waste anymore of this thread.


White91Z28 -
I prefer to use FMS SVO injectors. They are reasonably priced and I've never had a problem using them. Also, I think the Bosch injectors are pretty expensive, aren't they?

 

I prefer the Accel injectors. They have a few added features that other injectors supposedly don't. They are also that bright yellow color. No mistaking that color in the engine bay. I have a pair of Accels right now.

 

no they're only $100
http://www.slponline.com/view_produc...RTNUMBER=23051

 

probally run 36s you know what they say you can never have too much injector

 

24 lb injectors are PLENTY big enough for what you are doing.

 

24s will never feed a motor like that. You kiddin? Lotsa guys running 13s are using 36#ers. Gotta be something to it otherwise they wouldn't be using them. Just my observacations

 

Anything is better than stock

 

I know a few people that use 36lb injectors with Super-charged TPI small blocks!!

The 25 lb. injectors you were thinking about getting will work fine.

 

So lets see. I posted one of the useable formulas for injector sizing. Once again:
lbs/hr x 16 = horse power output
36 x 16 = 576

Why spend extra money on those injectors when the TPI can not breath enough to warrant the use. That will be running rich. Too big of an injector can hurt volumetric efficency and maybe even part throttle cruising. You can lose some of the atomization and mixing qualities. As said before, go with 24s or 30s.

 

WHAT ABOUT IF YOU ARE SPRAYING, DO I HAVE TO USE BIGGER INJECTORS?, MY CAR HAS HAS ABOUT 450-500HP AND IS CARB, AND SWAPPING OVER TO PORTED HSR, AND I WANT TO SPRAY EVERYNOW AND THEN, SO WHAT SIZE INJECTORS SHOULD I USE, 42,48,50?????PLEASE HELP ME..