TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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Wassup guys i'll be building a 1986 305 lg4 block with 416 heads (heavily worked over) and 9.75 to 1 compression.
So exact engine specifics is just a fresh rebuild kit with hypereutectic pistons. All else is factory rebuild parts (cast 2 bolt main crank and cast rods using all stock bolts).
The heads will be heavily modded with a slight decking, cutting down the valve guides in case i feel like a bigger cam, 3 angle valve job and a back cut, valve seat enlargement to run 1.94,1.6 valves (stock is 1.84/1.5), and of course lots of diy porting by a newby so it may not turn out perfect but, it will be decent.
i plan to run an edelbrock performer rpm manifold or weiand stealth with a tuned tbi setup on top of it (using an ebl computer), 1 5/8 by 2.5 or 3 in collector headers with a 3in catback will come off of the sides. (cam must be computer friendly). Behind it will be a 2,000 rpm stall convertor, behind it will be a 700r4, behind it will be a 3.23-3.73 rearend.
Sorry that was realy lengthy. So here comes the selections (btw i do plan to run 1.6 full roller rockers),
Biggest thing is it's my daily driver and i am a first time tuner so i think 112 or higher lsa is probably a must along with not to high of duration, I'd like to have close to around .500 lift at the rockers with 1.6 ratio rocker arms, the goal is to have basially a very street friendly low end/mid range engine with about 300hp and 350 trq at the flywheel...
any questions, just ask btw if you can't decide on just 1 cam give me your top 3 (or if you have other recomendations post them up).
Right now i'm leaning towards the lunati vodoo 262/268 grind or the 268/280 xfi grind. Basically my thoughts were the extra lift should add a couple pony's.
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If it makes any difference comp recomended the xe256 but, i think it's to mild and much to low lift and not a wide enough lsa........
In otherwords i think i could pick a better match.
Right now i'm thinking the lunati vodoo 262/268 grind would be about perfect with the 112 lsa and high lift for it's duration.
Just curious on how hard it would be to tune for a first time tuner, i plan to add the 1.6 rockers to my current engine, and headers and the catback which i will tune before i drop the new engine in but, i will still have a completely different head/cam package so i'm unsure of how bad or decently it will run with an ebl setup with just tuning for rockers and headers/ intake manifold.
will stock 305 injectors be fine at a higher fuel pressure or should i go with bigger injectors? i will need to fuel it until 5,500rpms at say an optimistic 350hp.
Last question is, will a ultimate tbi modded stock 305 tb be a restriction at these hp levels (my guess is yes), but, if not that's even better for me.
Last edited by flaming-ford; 07-17-2006 at 08:47 PM.
Right now i'm thinking the lunati vodoo 262/268 grind would be about perfect with the 112 lsa and high lift for it's duration.
I agree. Good torque, peak power at just over 5500 rpm ...and shouldn't be too difficult to tune. Really nice street cam for a 305 TBI.
Quote:
will stock 305 injectors be fine at a higher fuel pressure or should i go with bigger injectors? i will need to fuel it until 5,500rpms at say an optimistic 350hp.
GM TBI injectors can take up to 30 psi before they start to leak, so your's will be fine with a boost in fuel pressure. If your fuel pump can deliver it, the injectors can take it. 350hp at 5500 rpm is high for 55lb injectors though. You can find the formula on the 'net somewhere (I can't remember it off-hand), but I know that you have to crank 90 lb injectors to 16 psi to support 350 hp. I'd get some bigger injectors at that level of power.
Quote:
Last question is, will a ultimate tbi modded stock 305 tb be a restriction at these hp levels (my guess is yes), but, if not that's even better for me.
An ultimate TBI modded TBI (Rochester 220) should flow somewhere around 550 cfm (a fairly confident estimation), which should be fine for a 305 making 350 hp at 5500 rpm.
I agree. Good torque, peak power at just over 5500 rpm ...and shouldn't be too difficult to tune. Really nice street cam for a 305 TBI.
GM TBI injectors can take up to 30 psi before they start to leak, so your's will be fine with a boost in fuel pressure. If your fuel pump can deliver it, the injectors can take it. 350hp at 5500 rpm is high for 55lb injectors though. You can find the formula on the 'net somewhere (I can't remember it off-hand), but I know that you have to crank 90 lb injectors to 16 psi to support 350 hp. I'd get some bigger injectors at that level of power.
An ultimate TBI modded TBI (Rochester 220) should flow somewhere around 550 cfm (a fairly confident estimation), which should be fine for a 305 making 350 hp at 5500 rpm.
Awesome response just my thoughts! i appreciate you reading the whole thing out and answering everything.
