90 Suburban TBI to L31 swap

[Brett68]

I used the search function and did not find the exact answer to my quandry.

Can I install a L31 Vortec long block with GM TBI intake p/n 12496821 into my 90 V2500 Suburban? Other than a new PROM what else would I need to do?

My apologies if this has been beaten to death. I've seen plenty of vortec head swap topics. But none on the entire long block using the tbi vortec intake.

Thanks in advance.
Brett in Boise

 

[dave w]

I used the search function and did not find the exact answer to my quandry.

Can I install a L31 Vortec long block with GM TBI intake p/n 12496821 into my 90 V2500 Suburban? Other than a new PROM what else would I need to do?

My apologies if this has been beaten to death. I've seen plenty of vortec head swap topics. But none on the entire long block using the tbi vortec intake.

Thanks in advance.
Brett in Boise

I did something similar for my 93 GMC, well similar as in upgrading to a roller camshaft and keeping TBI. I reused the factory 93 TBI heads and upgraded to a 454 throttle body with 350 injectors.

Yes, the PROM will need reprogramming.

What I'm not sure about is the L31 long block timing cover, harmonic balancer, and oil pan. I don't know if the oil pan, timing cover, and harmonic balancer from the 90 V2500 Suburban will work on the L31 long block.

dave w

 

[Brett68]

It would be a long block swap so the oil pan, timing cover and balancer would be on it. I would have to find out if my accessories bolt up or not.

Or would it be simpler to just do the vortec head/intake swap on a tbi bottom end with a computer friendly cam?

 

[dave w]

It would be a long block swap so the oil pan, timing cover and balancer would be on it. I would have to find out if my accessories bolt up or not.

Or would it be simpler to just do the vortec head/intake swap on a tbi bottom end with a computer friendly cam?

The accessories from the 90 Suburban will swap onto the Vortec engine.

dave w

 

[63chevyll]

I may have to look into the prom thing, but i have done a vortec long block into a tbi engine with the stock computer and prom and it worked real well.

the balancer is slightly different on the vortec engines, it just depends if the crank sensor ring is on the crank or not.

if its new i hope they put the right one on it.
good luck

 

[Brett68]

I may have to look into the prom thing, but i have done a vortec long block into a tbi engine with the stock computer and prom and it worked real well.

the balancer is slightly different on the vortec engines, it just depends if the crank sensor ring is on the crank or not.

if its new i hope they put the right one on it.
good luck

I'd like to hear more about your swap!

I've got around 150k on the current motor. I've only had it a little over a year and put about 8k miles on it. It runs ok. Strange oil consumption problem, drinks about a quart every 200-300 miles. No oil leaks. The plugs look perfect. The passenger rear corner of the intake is leaking coolant(oil consumption?).The timing chain is worn. The balancer is seperating. There is no rust and the AC and four wheel works great. Locally it is only worth $1500 no matter what I do to it. If I do an engine change I'll be married to this suburban. So I would like to do an upgrade if I do.

Thanks All
Brett in Boise

 

[Brett68]

Passed on a 93 ifs rig. So I'll stay with the 90.

Still interested in tech tips on installing a L31 engine.

thanks
Brett in Boise

 

[bronc3buster842001]

I did something similar for my 93 GMC, well similar as in upgrading to a roller camshaft and keeping TBI. I reused the factory 93 TBI heads and upgraded to a 454 throttle body with 350 injectors.

Yes, the PROM will need reprogramming.

What I'm not sure about is the L31 long block timing cover, harmonic balancer, and oil pan. I don't know if the oil pan, timing cover, and harmonic balancer from the 90 V2500 Suburban will work on the L31 long block.

dave w

The timing cover, oil pan, and balancer will interchange from any SBC as long as it the one piece rear main. The timing cover will be minus 2 bolts, IIRC, but works fine.

 

[dave w]

The timing cover, oil pan, and balancer will interchange from any SBC as long as it the one piece rear main. The timing cover will be minus 2 bolts, IIRC, but works fine.

Here are a couple pics I have a L31 Vortec timing cover, harmonic balancer, crank position sensor and and reluctor. According to my calipers, the old SBC and L31 Vortec harmonic balancers ARE NOT interchangeable because the of the reluctor ring used for the crank position sensor. In God I Trust, everything else gets measured!

dave w

 

[bronc3buster842001]

Everything else should interchange. I forgot about the reluctor ring.

 

[Brett68]

Looks to be a lengthy, lot of thinking kind of swap. I may just do the vortec head upgrade with a suitible cam, ecm chip upgrade.

 

[dave w]

Looks to be a lengthy, lot of thinking kind of swap. I may just do the vortec head upgrade with a suitible cam, ecm chip upgrade.

You hit the nail on the head with the above comment.

I've done several engine / performance upgrades. A few things that always need to be considered when doing EFI performance upgrades.

1. Budget - Sometimes the budget can get out of control if planning is not detailed enough. Sometimes the initial budgeting will not include things like a starter motor, alternator, belts, hoses, plugs, wires, filters, oil, anti-freeze, gaskets, torque wrench calibrations, and several other low cost parts / services that can really add up fast? Sometimes the budget only considers just the "go faster" parts list?
2. Time - Sometimes an engine performance upgrade can take more time than first thought? Maybe an assistant who has obligated time to help has a change in plans and is not available? Somehow the vehicle got disabled until the helpful assistant can re-schedule time to get back on task and help out?
3. Skill Sets - How much can be done without the help of others? Maybe a trip to the machine shop is needed? Maybe some tutorial time with EFI tuning software / hardware is needed? The general rule is, the more you can do yourself, the better the overall performance gain / per dollar?
4. Expected Performance - Is the expected performance gain really worth the time and expense? I often wonder, could the money from selling the proposed project vehicle be sold "as is": then add the money for proposed budget to get another vehicle with the performance expected? I've seen a vehicle owner install a crate 502 into an 87 K2500 4x4, then spend even more money to get it to "run right". But I always wonder, maybe that used 2001 K2500 4x4 with the 8.1 Liter / Allison Transmission might have been a better performance upgrade after all?

dave w

 

[Brett68]

I like your #4 point. I would agree. That is why last thursday I bought a 93 k2500 Suburban with a 454/4l80e combination. Just upkeep and replacement of high mileage parts. Not much modding necessary for the job it will do.

The 90 just became relegated to trail duty in the Idaho mountains. No longer the road trip, family truckster. Optimizing the engine with appropriate upgrades in the future no longer require it to be completed in a weekend.

Thanks Dave w

Brett in Boise