What size injector for 4.6/blower

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bandon
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Stroker Displacement: 4.6
Vehicle Year: 91-4
Vehicle Make: JEEP
Vehicle Model: YJ

What size injector for 4.6/blower

Post by bandon »

Okay Ive been searching for about a week now and cant decide, I have 30lb injectors now and thinking about getting the Bosch 42lb green injectors. Ive done the formulas but it still seems too high.
My specs are 4.6 stroker, auto, 4.56, 35" , Hesco head, 99 intake, avenger blower w/7psi,inter cooler, 68mm F&B throttle body,vortech super FMU, apexi neo, msd btm boost retard, kenne bell boost a pump, and two walbros, no cat, all borla exhaust. Horsepower 400-450 ?? Stumbles a little when I really get on it then takes off. Is 42lb too big ?
YJ is the shop for ring and pinion ( broken locker) for three weeks!!!!
So Im working on my shopping list. Also looking at the Split second controller, and getting rid rid of my "Jules Verne" vacuum controllers.

Thanks
YJ,4.6 stroker/blower,Hesco Alum head,SOA SYE D44, 35" ,PSC ,Borla,AEM FMU, apexi neo, bap,2 walbros,2 Optimas, btm MSD, hydroboost, pw, PICS: http://photobucket.com/albums/b207/bandon_/
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SilverXJ
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Stroker Displacement: 4.6L
Vehicle Year: 2000
Vehicle Make: Jeep
Vehicle Model: Cherokee
Location: Radford, Va

Re: What size injector for 4.6/blower

Post by SilverXJ »

I'd stay with the 30s.... unless you have proof that it is going lean at the top end. I didn't see a wideband in your list there.

BTW, from my experience those injector calcs are crap for our engines.
CobraMarty
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Re: What size injector for 4.6/blower

Post by CobraMarty »

It sounds like you really need to get it on a dyno and get a real HP number and A/F ratio. Without it is just too hard to guess.
1998 XJ 2D AW4 32"MTR 3.55 4.5"RC JCR Slider Magnaflow 150rwHP/174rwTQ=> Sprintex SC Gibson Header 6lb 120-140*IAT 211rwHP/274rwTQ WasherFluid Inj 70mmTB 7.5lb 100-120*IAT=>Now 12 pounds Boost=> +BV ported head
99 XJ M62 S/C
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SilverXJ
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Location: Radford, Va

Re: What size injector for 4.6/blower

Post by SilverXJ »

You don't need to go to a dyno to figure the correct sized injectors.
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bandon
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Re: What size injector for 4.6/blower

Post by bandon »

Thanks for the quick responses, Ive got a wideband/ AF/ and EGT. It just seems to wind up kind of slow. If I punch it it will go lean then go rich, Thought it could be a flow issue. My pressure could be a little higher runs about 36 psi. With 2 inline walbros and a boost a pump, I thought the only restriction was injectors. Cant wait to get rid of the Vortech super FMU seems to stick a litle. I will try to up the pressure see what happens.

Thanks
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YJ,4.6 stroker/blower,Hesco Alum head,SOA SYE D44, 35" ,PSC ,Borla,AEM FMU, apexi neo, bap,2 walbros,2 Optimas, btm MSD, hydroboost, pw, PICS: http://photobucket.com/albums/b207/bandon_/
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SilverXJ
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Posts: 5790
Joined: February 14th, 2008, 7:14 am
Stroker Displacement: 4.6L
Vehicle Year: 2000
Vehicle Make: Jeep
Vehicle Model: Cherokee
Location: Radford, Va

Re: What size injector for 4.6/blower

Post by SilverXJ »

Oh right... I forgot that was your aircraft panel. Does the fuel pressure do anything odd when you punch it and it goes lean then rich?
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bandon
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Vehicle Model: YJ

Re: What size injector for 4.6/blower

Post by bandon »

The fuel pressure usually goes up (and down) as I depress and release the accelerator,as if directly proportional to each other.( It idles at about 39 psi) THEN the FMU and boost a pump kick in and pressure jumps to
50psi or more until I come out of boost. Lately fuel pressure stays at 39psi and might increase 10psi in boost. I suspect the FMU as every spring coming out of storage it has some kind of sticking issue.
Why the FMU allows the pressure to fluctuate with the throttle I don't know. Hopefully a new piggy back system will smooth things out.

For my OBD1 system should I go with Split second or AEM ?? About six years ago I contacted split second and they said their FIC controller may or may not work with my 91 OBD1 system. Since then I have seen numerous posts about it working just fine. I think I just wont have all the bells and whistles that it provides for the OBD2 systems.
Bottom line: for a stroked blower OBD1 whats the best controller?
Thanks for reading my ramblings.
YJ,4.6 stroker/blower,Hesco Alum head,SOA SYE D44, 35" ,PSC ,Borla,AEM FMU, apexi neo, bap,2 walbros,2 Optimas, btm MSD, hydroboost, pw, PICS: http://photobucket.com/albums/b207/bandon_/
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