Experts, which injectors to get? Thanks.

Pokageek · Aug 21, 2005

Hi All,

Just wondering with the combo in my sig which injectors and MAF to get? I do plan on getting edelbrock performer heads with in 6 months to add to the combo and a tune. I would like the car to be able to handle 400 or plus flywheel with the combo. I am figuring I should be around 380FWHP with the heads and all. Thanks all!!

94gts · Aug 21, 2005

i dont think with those mods you will be 400 hp.....but 24's are supposed to be good for 400hp so i say go with them and an 80mm Pro m if you can find one.

Killercanary · Aug 21, 2005

24's will get you by with that combo, but 30's will allow you a little room to grow if you ever decide to re-do that 306 and make a 331/347 out of it, or add some spray to it.

Pokageek · Aug 21, 2005

Thanks guys! Thanks Killercanary. BTW, you are definitely setting the bar! It's nice to know we can eventually get there in a vert with the right combo.

I think I will go with the 30# injectors. I plan on using the 306 for a long time as it only has about 400 miles on er right now. The rest I am doing a piece at a time even though I wish I could do it all ..now, lol.

Also, why 80mm? What is the HP limitation on the 75MAF? Just curious.

ASIDE: Also, I have gotten mixed opinions on the throttle body. Anywhere from 65mm-75mm. Any of you guys actually played with that one and have 1st hand experience as to what is BS and what is not? I have even heard not to waste the money on a TB.

Pokageek · Aug 21, 2005

Also, what does "matched" fuel inj mean? Why is it so much more money?

ponyboy19 · Aug 21, 2005

Pokageek said:
I think I will go with the 30# injectors.

Also, why 80mm? What is the HP limitation on the 75MAF? Just curious.

ASIDE: Also, I have gotten mixed opinions on the throttle body. Anywhere from 65mm-75mm.

30's are a good choice. I've always figured if I need 24's for a H/C/I set up then I'm going right to 30's and I had no trouble doing so.

75mm bullet would work fine, but if it were me, I'd look for a new/used pro m 77mm calibrated for 30's.

I use to run a H/C/I n/a with the stock TB and it ran great. Switched to a 65mm and didn't see any improvements at the track. But if I were doing it, I'd go with a 65-70mm TB on a 306 and leave the 75mm for the strokers that are breathing harder and spinning higher.

Pokageek · Aug 22, 2005

Thanks ponyboy19 for the first hand experience and advice. I am still wondering what matched injectors means. I will post back if I find the answer.

V8302stangs · Aug 22, 2005

Hey guys - I bought used 24lbers a while back and have a while before I am going to use them, but just wondering if anyone knew a way to test injectors without putting them on the motor. I know it's unlikely but might as well ask.

CManT1914 · Aug 22, 2005

Pokageek, I hate to tell you, but I doubt you'll be seeing 380hp with that b-303 combo.

On the other hand, while 24's will work for what you want, you might wanna step up to 30's now so you don't have to redo it in the future. But you might need to get a tune if you go with 30's. I'm having problems with mine, my car is running really rich with them.

281pony · Aug 22, 2005

flow matched injectors are exactly what they sound like. they flow exactly the same amount of fuel to each cylinder.

fwiw, i had 24's on my 331 and ended up going to 30's. runs alot smoother. no issues with mine. im also using a 70mm tb and have been since it was on my 302 and its been good on both.

DarkProphet · Aug 22, 2005

Im running 36's on my engine, which SHOULD hit around 320-340 at the wheels, ill find out on wednesday.
Matched injectors are all tested for their flow against eachother, then ones that are right on the money are selected and packaged together. Most injectors have a certian % of deviation from their said performance. For example if you buy 24lb injectors, some in the box might actually flow somewhere less then they should, some might flow more, some might be dead on, its just fluctuation in the manufacturing. Hope i answered your question, they are more expensive cause your guranteed to get the right flow rate.

Pokageek · Aug 22, 2005

DarkProphet said:
Im running 36's on my engine, which SHOULD hit around 320-340 at the wheels, ill find out on wednesday.
Matched injectors are all tested for their flow against eachother, then ones that are right on the money are selected and packaged together. Most injectors have a certian % of deviation from their said performance. For example if you buy 24lb injectors, some in the box might actually flow somewhere less then they should, some might flow more, some might be dead on, its just fluctuation in the manufacturing. Hope i answered your question, they are more expensive cause your guranteed to get the right flow rate.

Thanks Darprophet and everyone. Yes this makes sense. Any idea of the hp with that combo? reason is, I looked at similar combos and estimated 380FW. Anyone think it is worth getting "matched?" I am guessing no unless there is some reason you are on the edge of the power and need it precise or something. Wonder if factory comes matched?

CManT1914, thanks for the input. I am also wondering, shouldn't your car be running a lot faster with that combo? Is something off? ... EDIT: oops just saw that was b4 tyhe HCI

"But you might need to get a tune if you go with 30's. I'm having problems with mine, my car is running really rich with them."

I think you are right. I am prob way past need for a tune already considering our stock tune is for only 220HP.

CManT1914 · Aug 22, 2005

Pokageek said:
CManT1914, thanks for the input. I am also wondering, shouldn't your car be running a lot faster with that combo? Is something off? ... EDIT: oops just saw that was b4 tyhe HCI

"But you might need to get a tune if you go with 30's. I'm having problems with mine, my car is running really rich with them."

I think you are right. I am prob way past need for a tune already considering our stock tune is for only 220HP.

lol, yea, 14.1 with just the intake, gears, h-pipe and throttle body. Hopefully I will surpass 13's all-together and hit 12's when I get it running right and hit the track.

Oh yea, it's really not worth it to get matched injectors on street setups, usually the only guys that run those are pure drag cars. Something to think about.

That, and the computer is always gonna think it has 19lb injectors in there until you retune it. Even recalibrating a maf to "trick" the computer is only gonna do so much.

Pokageek · Aug 22, 2005

Nice write up on the car-domain too. Looks like it is spot on. That is amazing that the intake took your times down to 14.1 from 14.8. It may have been that the intake was the bottle neck in the combo. Just goes to show how restricted our cars are from the factory.

Killercanary · Aug 22, 2005

Pokageek said:
Nice write up on the car-domain too. Looks like it is spot on. That is amazing that the intake took your times down to 14.1 from 14.8. It may have been that the intake was the bottle neck in the combo. Just goes to show how restricted our cars are from the factory.

Don't be mislead though, the difference in ET is obviously due to his 60' times more than anything else, he went from a 2.4 to a 2.1, that alone is worth around 5 tenths or more typically. The intake is still a good mod though for a stock headed car.

Pokageek said:
Thanks Killercanary. BTW, you are definitely setting the bar! It's nice to know we can eventually get there in a vert with the right combo

Thanks! Its great to see other convertible owners that are stepping it up! Good luck with the new setup and keep us posted on your times.

CManT1914 · Aug 22, 2005

Killercanary said:
Don't be mislead though, the difference in ET is obviously due to his 60' times more than anything else, he went from a 2.4 to a 2.1, that alone is worth around 5 tenths or more typically. The intake is still a good mod though for a stock headed car.

But I did gain nearly 4 mph.

EDIT: I just noticed I'm missing one of my best runs in there (before the intake). I went from a 14.89@94.71 to a 14.80@95.27 with just practice. I pulled a 2.3 I think on that run.

ponyboy19 · Aug 22, 2005

here is a work sheet to help you figure out what you need. You have to remember there are different factors like, psi, duty cycle, and BSFC that all factor into how much hp an injector can support. This may help you out. http://www.rceng.com./technical.htm#WORKSHEET

Killercanary · Aug 22, 2005

CManT1914 said:
But I did gain nearly 4 mph.

That is true and THAT is a good indication as to what to expect from an intake swap. I went from a 14.6 at 94.89mph to a 14.3 at 97.2mph with an intake and TB swap, then to a 13.83 at 98.55mph with nitto DR's and a homemade CAI, you definitely had 13's in your car with just a little more traction too!

rockin_rick · Aug 23, 2005

I use flow matched 24's with my combo, and the 24's are right at their limit. 24's should be fine with your combo, but 30's still aren't a bad idea.

My flow matched injectors all flow within 0.004 lb/hr of each other. If your intake was (air) flow matched, then it may make a real difference, but otherwise, not really. BUT they certainly can't hurt. What I like is that I know exactly what they flow, and can enter that value into the tweecer.

Check out gene evans ford for good prices.

Rick

BlackVert · Aug 23, 2005

rockin_rick said:
I use flow matched 24's with my combo, and the 24's are right at their limit. 24's should be fine with your combo, but 30's still aren't a bad idea.

My flow matched injectors all flow within 0.004 lb/hr of each other. If your intake was (air) flow matched, then it may make a real difference, but otherwise, not really. BUT they certainly can't hurt. What I like is that I know exactly what they flow, and can enter that value into the tweecer.

Check out gene evans ford for good prices.

Rick

good point about knowing EXACTLY what they flow ... takes that part of the guess work out of the tuning process.

if you go to 30#ers, i have dibs on your 24#ers!

Experts, which injectors to get? Thanks.

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