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TBI upgrade

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Fiveminutesinthegarage

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Hey y’all I’m new here..I have 89 k5 on 37’s..700r..5.38 gear..stock tbi motor….about a year ago I added vortec heads intake spacer salad bowl and had chip programmed..question is I want a little more..1102 cam added also..if I go with flat tops..Lunati can 207/213 will it mess with computer?…also have 381 fuel pump..I will do work myself except for chip..5 minute job lol thanks
 
I am not sure if that cam is enough to mess up the tbi computer. I know they don't like bigger cams very much.
Your chip tuner would be the one to ask if that would work.
 
check the injection section here. different forum with fuel injection specific threads. search around in there- lots of TBI info.

might be time to look at your cam profile and see if maybe its time for a different stall torque converter for that 700? could help match the power band and gearing/tires
 
A long overdue project of mine -- is putting a 454 TBI onto a vortec-intake 383. Not stalled because of the setup, just life in general. I have gotten it to fire, but haven't gotten into the tuning aspect of it.
 
SnackPack said:
A long overdue project of mine -- is putting a 454 TBI onto a vortec-intake 383. Not stalled because of the setup, just life in general. I have gotten it to fire, but haven't gotten into the tuning aspect of it.
Click to expand...
from what I remember about this- gonna have some big match up problems unless you have a carb style intake that is wide open under a spread bore carb, and then use the factory TBI adapter that mates the tbi to that intake pattern.

also- some old threads in the injection section? I seem to remember people saying it could be really easy to burn up a healthy 383 with fueling and lean condition problems? maybe that was assuming a 350 TBI unit though?
 
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I used a GM 12496821 intake... the 454 TBI bolts right up, except the bores are a little small. I got those opened up by a machine shop to match the (52mm I think?) TBI bores.

As for fuel, I'm capable of tuning chips for VE, and am also using a wideband o2.
 
scouthead said:
check the injection section here. different forum with fuel injection specific threads. search around in there- lots of TBI info.

might be time to look at your cam profile and see if maybe its time for a different stall torque converter for that 700? could help match the power band and gearing/tires
Click to expand...
 
I didn’t include all info in profile..I have a 2100 stall..locks in 4th only
scouthead said:
from what I remember about this- gonna have some big match up problems unless you have a carb style intake that is wide open under a spread bore carb, and then use the factory TBI adapter that mates the tbi to that intake pattern.

also- some old threads in the injection section? I seem to remember people saying it could be really easy to burn up a healthy 383 with fueling and lean condition problems? maybe that was assuming a 350 TBI unit though?
Click to expand...
ive done all mods and have a aluminum adapter to my intake..injector pod..1” spacer drop air cleani
jake 03 said:
I am not sure if that cam is enough to mess up the tbi computer. I know they don't like bigger cams very much.
Your chip tuner would be the one to ask if that would work.
Click to expand...

scouthead said:
check the injection section here. different forum with fuel injection specific threads. search around in there- lots of TBI info.

might be time to look at your cam profile and see if maybe its time for a different stall torque converter for that 700? could help match the power band and gearing/tires
Click to expand...
 
you are probably at the point of diminishing returns...
I've got one punched out .060, 360 cubic inches baby! -and running right at 9.1 to 1 compression with flat tops. Cam is basically a fancy billet version of the stock vortec 5.7 roller cam. roller tipped rockers (meh) lots of head work on factory tbi heads (if you have the vortec heads you are prob better off)... have tried a factory tbi intake bored out, tried the edlebrock tbi manifold... yes currently running aluminum "tbi power spacer"... larger bore in the throttle body, injector pod spacers... blah blah blah... with the 68lb injectors and a chip it ran HARD - im talking wow what a difference, but it ran hot and I needed a lot of time tuning that I did not have to dedicate. ended up back on 55lb injectors with correct chip for the manual trans.

I live in californistan, and the air research board is a bunch of crooks. there is no way i can do a motor swap. I had to work with what i could, and make it LOOK like a factory motor... and had to make it pass local emissions tests. otherwise I would have never gone to all the trouble trying to ring power out of that type of motor.


How about looking for the old supercharger that used to be avail for the tbi motors???? supposed to block all access to the distributor, and make tune ups a pain in the butt! -but could pack a punch that you wont get anywhere else without changing to a bigger or newer gen motor?
 
I think I'd skip flat tops, unless you just absolutely desire running higher octane fuel.

L31's come with dished pistons, so going flat top may put you into detonation territory on cheap gas. Compression is still 9.1:1, that's pretty healthy for a SBC on cheap gas.
 
dyeager535 said:
I think I'd skip flat tops, unless you just absolutely desire running higher octane fuel.

L31's come with dished pistons, so going flat top may put you into detonation territory on cheap gas. Compression is still 9.1:1, that's pretty healthy for a SBC on cheap gas.
Click to expand...
need to check all the volumes and measure your head gaskets... I think if he started with a 5.7 that was in his '89 -he has an LO5 that is now wearing vortec heads... so who the heck knows what the current compression ratio is???? Also I actually see L31 listed for sale from dealers and several places @ 9.3:1 with factory iron heads... I assume the L31 had different versions based off of GVWR and emissions requirements just like the LO5 did?

both of the last 2 LO5s that I cracked open had the factory dished pistons and were around 8.5:1 with the factory heads.

in my K5, now as a 5.9 liter @ 9.1:1, with the flat tops and with the factory timing back in the chip, I've never run anything other than 87 octane
in my case I was building from the block up, and needed new pistons anyway. also, the particular flat tops I have have valve reliefs cut into them... compression ratio with flat tops of two different brands with the same deck height can still vary with style/shape/depth of any relief cuts for the valves...

-would I take a running motor and tear it down to swap from dished to flat top pistons thinking that was going to make a noticeable power increase all by itself??? heck no that's nuts, and if the rest of the engine wasn't built around those flat tops? anybody just sayin a prayer and crossing their fingers better hope they don't bend a valve or end up with a motor that pings itself to death prematurely?
 
also, reducing internal friction in an LO5 should be "free horsepower" right???

well, turns out it can be really expensive lol

but, without making changes to the engine type/design... I have a double row "roller" timimg chain on my current TBI motor. supposed to be stronger than stock and less friction ? -sure/great... i had to shave the face of the block to make that fit, but does fit inside the factory timing chain cover.

I started with a block that had factory roller cam provisions. The cam I'm using has specs almost identical to the factory Vortec/L31 cams... the L31 is a noticeable step up in power from a LO5, but I think a lot of that was the heads themselves, and not having a corked up intake system like the TBI motors? anyay, lets just say im running a factory vortec roller cam instead of the hydraulic tappet style that it originally had.

I have self centering roller tipped rocker arms... not sure I can recommend those. I had thought maybe it would reduce friction and wear on the valves. I was in this engine recently and had a look at everything after about 65,000 hard miles... cant say as if they accomplished anything, and I'm probably approaching the need for new valve guides. cylinder compression is still fantastic, so I'm sure the valves are seating, but a few of them felt a bit looser in the guides than the others. REAL roller rockers with a rolling pivot are supposed to reduce quite a bit of friction, and Ive even heard of TBI guys having problems getting their idle down into the correct range after installing them.

If I have to build another TBI motor, I will probably do real roller rockers and look into various coating options on the piston skirts... but anyway, just having the vortec heads and your chip tuned and corrected as you said in your first posts, you have probably eclipsed the power output of any TBI motor I'm interested in building. I will stay within my emissions compliance needs and just live with it, or move on to another platform if I decide I really cant live with it.
 
I've got some Comp Pro Magnum Guided Roller Rockers in my current engine that are 20 years old this year actually! Been through two motors with them, including one a stud broke off in.

Nothing bad to say. When I swapped engines I checked the roller bearings, and while some might have a tiny bit of play in them, they were good to go I felt. Especially since I put so few miles on them each year. They MIGHT have 50K on them at this point.

I did contact Comp, they can rebuild them if someone felt they wanted to.

Doubt they freed up any power I would notice, my fuel economy didn't get substantially better or anything, but that they've lasted me this long, they were probably worth the cost. I can't recall what I paid back then, but I wouldn't be surprised if it was $3-400.
 
scouthead said:
need to check all the volumes and measure your head gaskets... I think if he started with a 5.7 that was in his '89 -he has an LO5 that is now wearing vortec heads... so who the heck knows what the current compression ratio is???? Also I actually see L31 listed for sale from dealers and several places @ 9.3:1 with factory iron heads... I assume the L31 had different versions based off of GVWR and emissions requirements just like the LO5 did?

both of the last 2 LO5s that I cracked open had the factory dished pistons and were around 8.5:1 with the factory heads.

in my K5, now as a 5.9 liter @ 9.1:1, with the flat tops and with the factory timing back in the chip, I've never run anything other than 87 octane
in my case I was building from the block up, and needed new pistons anyway. also, the particular flat tops I have have valve reliefs cut into them... compression ratio with flat tops of two different brands with the same deck height can still vary with style/shape/depth of any relief cuts for the valves...

-would I take a running motor and tear it down to swap from dished to flat top pistons thinking that was going to make a noticeable power increase all by itself??? heck no that's nuts, and if the rest of the engine wasn't built around those flat tops? anybody just sayin a prayer and crossing their fingers better hope they don't bend a valve or end up with a motor that pings itself to death prematurely?
Click to expand...
Appreciate what you’ve said based on the information given I would’ve said the same thing..lol..blazer motor does have dished pistons and the TBI heads I measured were 65.4cc..my intake is a dual plane JEGS kinda reminds me of a 2101..as far as tearing down a running motor the answer is a big fat no!..I’m building another motor that has a little more power than what I have..this thing has a 6” lift 8 lug and disc brakes probably a million miles..when I get together I will make swap on a weekend I’ll be driving Chevelle in summer these are just daily drivers ..1094 head gasket is being used and will continue to be used..thanks for the comments
 
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