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TBI 350 Power Upgrades
- Thread starter aglinks
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The previous owner installed a new 3" pipe from the Y-collector back and deleted the cat (not my choice). I was thinking headers and a better Y-collector.
fuel psi up to 12-15 range . most stock have been found at 10.5-11psi .
cam is lawn mower size thing . even a basic cam for efi is way better . if you have a roller cam block then swap in the lt1 cam and roller parts . any cam swap = chip burnt .
some say timming is checked and set at zero with wire unpluged . but others say they found great results at 4* and locked down .
i dont care much for heat / noise / crappy fit of most headers . so your exhaust sound free now . unless you do a custom y-pipe with a unit like flowmaster or other for y-pipe builder parts .
stock tbi intake manifold is bit restrictive . some say good 4 barrel intake and adaptor plate back to tbi works good . but this is a fab job for brackets and other things .
as said find away to bump the compression up a bit . there weak in the stock form .
there is some good info here on how to play with them . and few threads have good feedback on the stuff used .
cam is lawn mower size thing . even a basic cam for efi is way better . if you have a roller cam block then swap in the lt1 cam and roller parts . any cam swap = chip burnt .
some say timming is checked and set at zero with wire unpluged . but others say they found great results at 4* and locked down .
i dont care much for heat / noise / crappy fit of most headers . so your exhaust sound free now . unless you do a custom y-pipe with a unit like flowmaster or other for y-pipe builder parts .
stock tbi intake manifold is bit restrictive . some say good 4 barrel intake and adaptor plate back to tbi works good . but this is a fab job for brackets and other things .
as said find away to bump the compression up a bit . there weak in the stock form .
there is some good info here on how to play with them . and few threads have good feedback on the stuff used .
rampage
3/4 ton status
Surprised no one mentioned this: http://m.ebay.com/itm/Tornado-Air-Intake-Management-System-KI-85-FREE-SHIPPING-/122386983943
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I just finished an LS swap in my CJ7 using an engine package from Tilden Motorspors. I'm looking to keep the burb as original as possible (wiring and plumbing and such) and upgrade the existing engine to put out a little more power. Maybe intake and exhaust? I'm not searching for huge gains, just that little extra bump to help the old burb up the steep grades.
And the cam.
superbuickguy
1/2 ton status
a 2 barrel tbi max hp is 350..... the best thing you can do once you get it breathing better is swap for an FI tech... that said, 454 TBIs are larger/high fuel capacity. You can port the TBI to get more flow but you will always fight the low fuel pressure. To get more fuel you have to turn up the pressure 9 is stock, 12 you can get away with 15 and you'll have nice little fuel rockets popping off the top of your nicely ported TBI bowl that or you'll start dribbling past the seals.... the injector is surrounded by fuel and the fuel is kept in place with some pretty unsubstantial seals... that's why the first step in diagnosing problems with TBI is "watch fuel flow, fix drips". Note I haven't even started about the 4 bit computer that requires burning chips.... as I said, spent $700 on an FItech system.
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350HP is far more than I'm looking for. I was thinking 15-20HP gain. After I regeared to 4.56 the truck does great for 90% of my driving. It's just when I'm trying to keep 75 MPH on the freeway up a 6% grade that it gets strenuous. And do spacers really work? I've always been told they were more of a snake oil type product.
superbuickguy
1/2 ton status
I'm not a believer - spacers tend to move the power band further up on the rpm range.... it can 'create' more power but you also tend to lose a corresponding amount on the other end - which is great if you're racing dynos.
crazy money and still some fab work to make it function with throttle cable and tv cable correctly .
superbuickguy
1/2 ton status
the way to more hp is lose the ramp heads. Replace them and the intake with Vortec heads and intake - gain 100 hp, real, 100 hp gain. I'd leave the cam and lower end alone. I'd even leave stock, Vortec cast iron manifolds on it. Of course, that's why I mentioned the max hp of the TBI - with those mods you'll be bouncing very close to that 350 hp limit.... how do I know? see that FJ40 in my avatar - it has a TBI system in it over Vortec heads. Granted, I have a slightly warmer Comp Cam, but it really isn't much to write home about...
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Ok that sounds like a plan. I'll start hunting for a used intake. The new ones are SPENDY! Do you use the same push rods with the vortec heads?
Have you considered a GM crate L31 replacement? Good heads, roller cam, warranty. Under $2k.
You will still need either a Vortec-specific TBI intake, or a carbed Vortec intake and TBI adapter, plus a chip burn, and those won't be cheap either.
I doubt 10-15HP is going to get you what you want. Just my thinking. Would be nice to do a dollar per horsepower comparison, which is going to be arbitrary because most HP numbers are bunk, but it would be something.
Can never help myself when it comes to numbers:
L05 Crate: $10.14/hp
L31 Crate: $7.84/hp
L31 Heads: $25.60/hp
Headers: $4.80/hp
Cam: $4.13/hp
Intake: $23/hp
The two crate engines were just what I found quickly as an advertised price, and they sound about right. The heads are summits price for a pair. The headers were the cheapest small block long tubes summit listed for a Suburban, the cam was the second cheapest with no regard for performance, just cost. intake is the only TBI one Edelbrock makes. You can get cheaper by running carb+adapter I expect. Probably half that?
The numbers I used were based on generally accepted numbers, at least by me. Respectively, 190, 255, 25, 25, 15 and 15HP. Just don't forget, the L05 starts at 190HP. Adding 40HP doesn't get it to the L31 HP level.
Of course,to keep it simple, that ignores everything else that will skew those numbers. Gaskets, chip burning, exhaust work, timing chain, bolts, etc.
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I hadn't looked at the L31 but I have looked at Westcoast engines. I don't need the extra power so until this engine dies, it won't be coming out of the truck. If the engine were to come out of the truck I would likely spend the money to build a 383 stroker of the engine HAD to come out.
