Ok sometime this summer I planning to do a major rework of the LO3 in my 91' RS. Here is a list of the mods I'm planning, please let me know if there is anything I could add to improve this setup. Please do not flame me for my choice of intake ( I've heard it all before ).

I will be running a fully ported Crossfire Injection intake with all of the tricks ( basically its version of the ultimate TBI mods ) , this will be run my cars TBI computer, with some custom PROM tuning, ported LG4 heads ( stock valve size for now ), LT1 cam with 1.6 rockers, the usual fuel and ignition upgrades, ported TPI exhaust manifolds with 3" cat and Hooker catback. High stall S10 converter with 3.42s and SLP posi out back. Supsension upgrades planned too.

What do you guys think? I know I could of run headers and and 4 barrel intake w/adapter and ...... but I am trying to go low buck and wouldn't believe how cheap some of the parts listed above are. I'm hoping to get at least 230 hp out of this combo. Then if the 160,000 mile bottom end will take it, throw a 75 hp shot of nitrous in too.

 

you shoudl be able to get a good amount of power out of it. as long as you do a good job on the intake. they are about the worst cast quality intakes gm ever made.
the biggest part of your tuning is gonna be the timing portion of things.
how are you planning on regulating fuel? you have to make sure that both tb's see the same pressure or you are gonna have a hell of a time getting your fuel delivery right.
good luck

later
tim

 

Crossfire? What TBI unit?
The stock one off a Vette or something?
Is this what your car had originally?
L03 Crossfire?
Hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm.
It has possibility IF you are going to create/machine a new crossfire intake....
How far can you really go with it?
I'm just thinking out loud.
(I am imagining a full size, instead of severely bottlenecked, crossfire intake)
(using RamAir or Cowl)
Hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm.
My .02
Another thought:
What IF?
What if you crossed crossfire with runners?
Interesting thought.....
Hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm.

 

Ok, here is a little more info. The CFI setup is out of an 82' Z28. My car was not originally CFI, just plain old TBI. The mods to the intake constist of porting the runners, opening up the ends ( where most of the restriction is ), removing the EGR tunnel, polishing the casting, removing the swirl plates, 2" TBs, and 1/4" lid spacer. For now, the I will be running the TBs in series just like they were originally, using the stock 305 CFI injectors and VAFPR, if I find a set of 350 TBI injectors ( LO5? ) I might run the TBs in parallel with aftermarket regulator. I also going to run a TPI fuel pump. As far as tuning, a local CFI expert has offered to help me tune it after the swap. I hoping the car willl at least run with the stock PROM. I think it will, TOM400CFI is still using an 83' CFI computer in his car and it is much wilder than mine will be. Not sure how the CFI engines like to be timed, but the wimpy stock setting for a TBI car isn't gonna cut it, I thought I would advance the timing to the recommended setting for TBI engines and go from there.

 

Man you've just eliminated all the CFI intake's weak spots. The engine should wind up pretty high and if you shortened the runners on the inside; you could get even more RPM's but with the sacrifice of some torque. I would personally go with 3.73 rear end because the engine will make most of its power up high; the higher stall TC is a good idea. The car should scream if it hooks up right.

 

Hmmmm... interesting point. There is a 4cyl 4-speed car in the local junkyard with 3.73s. Maybe I need to get those gears.

 

Oh as far as runner length, I haven't really shortened them much, but I blended the transitions from plenum to runner, going to work them more, still not satisfied. I also thought about knife-edging the divider between the ports, its pretty thick and I think it would disturb flow. I'm not sure what surface finish I should have, mirror smooth or kinda rough?

Anybody want to guesstimate hp on this combo? I think this will actually be a good all around engine. CFI is a crossram, but even in ported form the runners are smaller than normal xrams so I don't think I'll lose all my low-end torque. Plus I'm not sure how much RPM my 160,000 shortblock will turn safely. One thing is for sure, it won't lay over and die at 4,000 rpm like nearly every original motor in a 3rd gen. Should suprise a Mustang or two .

I want to thank eveyone who has replied so far. I'm glad this thread hasn't become bogged down with "cease-fire" jokes.

 

My guess is about 230-250 HP if everything works. Not counting the Nitrous.
*With engine rebuild.....

 

BTW, what all should I replace? Of course, all the gaskets and such and I need a new timing chain, but what about things like pushrods? What is a good brand timing chain to buy? I see places selling the ones for roller engines for like $80, seems kinda high.

 

Any reputable brand for the timing chain will last a long time and work fine. You dont really have to change the pushrods, but if they seem to be a bit abused then; I heard Comp Cams make good pushrods, but again any reputable company will make a quality pushrod.

 

https://www.thirdgen.org/techbb2/sho...threadid=86748
Check out that thread!!!
Talk about opening it up!
:hail:

 

jsut check teh push rods before you decided to swap them. if you roll them back and forth on your bench and they are still straight, just reuse them. you only really have to worry about rods when they start to go out of true.
things like timing chains and gaskets. just go stock replacement. the only gaskets that i really believe need any real attention are head gaskets, they see a lot of pressure. the chains shoudl only really be like $45, that's how much mine was when i swapped it along with the cam.

later
tim