'88 TBI Suburban - Engine Overhaul - Help me plot this out

[ekulggats]

After establishing that my engine is probably completely fine-

**I want to do some mods to step up the power, possibly get a little MPG bump along with it. Get it more in line with the L31 'Vortec, maybe a little above without drastically reducing engine life, for 1500 or less preferably. **

STARTING WITH - a really solid 88 TBI engine, almost stock, 85k miles and pretty perfect maintenance. has the 'salad bowl' air cleaner mod with an aftermarket K&N air filter. Has a 21"magnaflow on the back, stock Y pipe, modern cat. Stock Oxy sensor. Stock exhaust manifold. Stock Cam. No chip yet. Stock V belt setup.

How would you guys go about getting the biggest improvements for 1500 or so? I'm willing to do the work, my buddy knows these in and out and will be able to assist me if I get stuck. We just did the valve seals on it but he's got a lot more experience than that. Not looking for monster power, just to update it somewhat and get a little more top end when called for.

I might just LS swap it sometime years in the future, for now I just want to open up this solid running engine a bit.

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[TreeGeared]

I think this also depends on the amount of time that you want to put into it. The TBI system does not respond well to significant engine mods such as a cam change. If you are willing to take the time to learn to tune then that opens up more options. A new EFI system could net more power through a bigger TB and more tunability but that will brake your budget.

Sounds like you have made some attempt at opening up the intake side. A set of long tube headers would be good start. I could feel some improvement when I added those to my 88.

To match a L31 the quick easy answer is L31 heads but then we are back to the fuel injection/tuning conundrum. Ultimate TBI mods and try your hand with a little port and polish on the existing heads could get you a small improvement but still not going to be a bit of a stretch to match an L31.

Start by thinking about what you want to do with and how long you are going to keep the truck. Then think about how much power you will need, fuel effieciency, and reliablity. You may find what you need/want can't be accomplished with a 1500 budget. Maybe better to just do some maintenance on the current engine and save for bigger upgrades down the road.

 

[Das Hatt]

Y pipe is probably the biggest restriction right now. You you could do shorty headers and a mandrel bent Y pipe to the cat as long as it's in the stock position. Bolts right in. Or you could do long tube headers and a custom pipe to the cat.

 

[ekulggats]

I'll probably start with Y pipe by the sound of it, Do I need to change to a heated sensor for that?

If I were to do a cam, what might be a mild - mild+cam I should look at? I have considering putting the Vortec heads on - The TBI cam is apparently notorious for being the sh!ttest cam that came in any small block -

How difficult is it to swap to rollers? Would valve springs be needed to get to an L31 ish spec?

I will be getting a chip from Harris tuning I believe if I go through the major engine mods. I've put a lot of blood sweat and tears into this thing, did a complete interior gut, and rebuild, soundproof, sound system install, valve seals, cleaned up and undercoated, been through months of roadtrips, cliff roads etc I will likely keep this thing a long time.

 

[PlayingWithTBI]

The TBI system does not respond well to significant engine mods such as a cam change.

Oh, IDK about that. I'm running a "383" with a TBI throttle body and putting out over 400HP with a 230/236° @ .050", .510/.520" lift cam and 10.3:1 compression but, it was a lot more than $1500

If I were to do a cam, what might be a mild - mild+cam I should look at?

The best thing to do is call your favorite cam company and tell them what you have and what you want out of it.

 

[Das Hatt]

I'll probably start with Y pipe by the sound of it, Do I need to change to a heated sensor for that?

The O2 sensor is located on the driver side manifold, not the Y pipe. So I guess technically you could leave the O2 sensor alone.

If you're thinking about going to a roller cam or some different heads, I would suggest new headers along with the Y pipe.

It says in your first post that it's a stock oxygen sensor. Does that mean original? From 1988? I would definitely change if that was the case, lol. But yes, if you decide to swap out the manifold for headers a heated O2 sensor is suggested.

 

[ekulggats]

The O2 sensor is located on the driver side manifold, not the Y pipe. So I guess technically you could leave the O2 sensor alone.

If you're thinking about going to a roller cam or some different heads, I would suggest new headers along with the Y pipe.

It says in your first post that it's a stock oxygen sensor. Does that mean original? From 1988? I would definitely change if that was the case, lol. But yes, if you decide to swap out the manifold for headers a heated O2 sensor is suggested.

My understanding of the O2 Sensor is that it is an unheated model, that the Y pipe on the TBI's is deliberately slow flowing to 'warm up' this unheated sensor, and that a heated sensor would be needed or preferred as a mod in this case

 

[PlayingWithTBI]

a heated sensor would be needed or preferred as a mod in this case

IDK if it needs a heated O2 but, I would always recommend one. That'll help keep your engine in Closed Loop at idle too.

 

[TreeGeared]

The TBI system does not respond well to significant engine mods such as a cam change.

Oh, IDK about that. I'm running a "383" with a TBI throttle body and putting out over 400HP with a 230/236° @ .050", .510/.520" lift cam and 10.3:1 compression but, it was a lot more than $1500

Are you running the 383 with that cam with the stock tune? I am guessing not. If the OP was willing to buy the tools to burn chips and learn the tuning then I would say go for heads and cam.

 

[evilunclegrimace]

The heated O2 will depend on the headers that you by some have the O2 close to the stock position and it does not cause any issues. If I was doing engine mods for that heavy beast I would be more concerned about bottom end torque as opposed to top end rpm and install an RV or cam designed for a plow truck.