Will 99+ intake manifold and injectors work for a stroker?

[K2ZJ]

I have a line on a 99+ intake manifold with fuel rail and injectors. Are those injectors large enough for a 4.7 (accurate power kit), big valve head, stroker? TIA

K2

[gradon]

Manifold yes, injectors no--they're 22.5#s on a 49psi rail, won't fit on the earlier harnesses and will flow less if you have a 39psi rail(<96). The highest flowing stock injectors were the gray tops, at 23.2#, used from 96-98. The gray tops didn't cut it on my 96 stroker. . .

[Comanche91]

Manifold yes, injectors no--they're 22.5#s on a 49psi rail, won't fit on the earlier harnesses and will flow less if you have a 39psi rail(<96). The highest flowing stock injectors were the gray tops, at 23.2#, used from 96-98. The gray tops didn't cut it on my 96 stroker. . .

The 99+ manifold and gray top injectors @ 49# make it just fine for moi. But I think the UniChip has a lot to do with that.

[gradon]

After my West coast trip in May, I'll be visiting the Unichip custom tune shop that's 11mi away, so thanks again Comanche for posting the results. I already maxed out the 25.5# LT1s via PSC1 trying to get 12.8:1afr with a load in 5th b/t 2k-3Krpm(it dropped slowly from 13.3-12.8), so maybe my ported head breathes too much air and needs the bigger injectors(I'm even curious about the 27#ers, just to experience the option).

[K2ZJ]

Thanks

[Comanche91]

After my West coast trip in May, I'll be visiting the Unichip custom tune shop that's 11mi away, so thanks again Comanche for posting the results. I already maxed out the 25.5# LT1s via PSC1 trying to get 12.8:1afr with a load in 5th b/t 2k-3Krpm(it dropped slowly from 13.3-12.8), so maybe my ported head breathes too much air and needs the bigger injectors(I'm even curious about the 27#ers, just to experience the option).

You're welcome Gradon. Will be very interested in your findings. Just curious - what kind of mileage are you getting w. the 25.5 LT1s? And at what FP are you set at?

[mendelmax]

Guys, why are you avoiding adjustable fuel regulators so much? I don't fully understand it- is it a matter of regulator price, or are there any other drawbacks? Because I just swapped the 99+ injectors into a 93 stroker and it runs perfectly fine on 55PSI. Probably I will have to adjust it a little more when we'll do exhaust and it will be able to rev higher, but still, it works as a budget solution.

Not that I don't consider bigger injectors as a better way of doing this, because they are better for sure, but I think these stock ones work too. And if they can be bought cheap, then why not? We got them almost for free with the manifold, so we decided we'll give them a shot.

[gradon]

I have a 96, so no return line w/ regulator that can be modded or swapped out. I haven't looked into adding a fpr, a higher psi fuel pump, nor have I monitored my existing fp(I know I should've already done it, with everything else I've monitored). What I do know is that I have light pinging in closed loop right before open loop(medium acelleration b/t 2.5K-3Krpm w/40-60%tp) and I can't add fuel because the pcm will pull it right back out(it probably needs to be 13.5-14.0:1 there, or else timing backed off 5*), so I don't think it's an issue with pressure, but with my high 8.57:1 dcr that has me a lil over the edge of pump fuel. If I WOT from stop, it's not there. I haven't been to the Sunoco that carries 104 or even seen an e85(maybe use 5 gallons with 10 gallons of 93) station around to see if it's still there. This last trip to PA averaging 70+mph up and down Mts for 202mi took 5/8 of a tank both ways. Normal city driving is 15-16mpg and highway 18-19(cause I don't stick to 55 or 65).

[Comanche91]

I have a 96, so no return line w/ regulator that can be modded or swapped out. I haven't looked into adding a fpr, a higher psi fuel pump, nor have I monitored my existing fp(I know I should've already done it, with everything else I've monitored). What I do know is that I have light pinging in closed loop right before open loop(medium acelleration b/t 2.5K-3Krpm w/40-60%tp) and I can't add fuel because the pcm will pull it right back out(it probably needs to be 13.5-14.0:1 there, or else timing backed off 5*), so I don't think it's an issue with pressure, but with my high 8.57:1 dcr that has me a lil over the edge of pump fuel. If I WOT from stop, it's not there. I haven't been to the Sunoco that carries 104 or even seen an e85(maybe use 5 gallons with 10 gallons of 93) station around to see if it's still there. This last trip to PA averaging 70+mph up and down Mts for 202mi took 5/8 of a tank both ways. Normal city driving is 15-16mpg and highway 18-19(cause I don't stick to 55 or 65).

Ah, forgot you had a 96. I have no pinging whatsoever using regular pump gas, at least that I can hear. It required some tweeking with the adj. FP regulator at the Hesco dyno. I'd definitely throw a gauge on your rail first thing though to be sure the pump is within specs. Your milege is about the same as mine too.