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1991 K5 LO5 Engine replacement PART 2 (The saga gets foggy)...

Rhinodrvr

Rhinodrvr

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OK..the plan was this motor...

http://paceperformance.com/i-648501...mc-full-size-trucks-g-van-up-to-7200-gvw.html

Now JEGS is running a special on GM replacement engines and I know the VORTEC motors produce more HP and torque. So now I have to ask, will this motor and intake work with my 1991 LO5 TBI?

http://www.jegs.com/i/Chevrolet-Performance/809/12530282K2/10002/-1?parentProductId=

http://www.jegs.com/i/Chevrolet-Performance/809/12496821/10002/-1



It looks like it will, but looks and actually are 2 different things. If I do go with this new set up, which is a 1996-2000 engine, do I need to do anything to my 91's current computer (new tune, chip, replace, etc?)

Thanks,
Rhinodrvr
 
It will work in your truck. My boss did one on a k1500 about 5 years ago. Had problems but I am pretty sure they were almost all related to work out tbi and dist. Ran good otherwise.
 
Tune for sure. Vortecs require way less timing, and that compression is up from stock, making timing even more of an issue. Fueling will likely be off quite a bit as well. Might be time for a new fuel pump.

Your intake won't bolt to those heads obviously. You can't easily run EGR if emissions is an issue, see the note on the intake page. Bolting a carbed Vortec intake on and running a TBI adapter is possible, certainly much less than that ~$300 TBI intake.

Vortecs add a lot of complexity to any build. The swirl port TBI heads seem to be capable of just about everything the Vortecs are up to a point. They aren't a bad truck head.

When you start talking about Vortecs and injection, you are often times going to break about even if you start looking at aftermarket heads that fit your existing intake...for under $1000 you can probably get into a set of fast burn style aluminum heads with 10:1 compression (doable on 87 with AL heads) that do everything the Vortecs do, with better springs and studs from the get-go. If you stick with cast iron heads, you can probably get it down to around $800.

A cam, flat top pistons, vortec-style heads and headers will probably get you over 300HP quite easily.
 
dyeager535 said:
Tune for sure. Vortecs require way more timing...
Click to expand...
Fixed it for ya! :waytogo:

Getting a chip to go with a new engine is not that hard, or expensive and will be one of the better choices of money spent for performance gained! One thing I always recommend to guys with an EFI vehicle is to get a cable to interface the truck to a laptop. This will also be your scantool, must own a scantool if you own a EFI vehicle, but also with software available record the data in a way that is usable to fine tune the chip.

I'm not sure if you can use that distributor?

Do they have any others on sale with a little more cam?

The upgrade to Vortec heads and roller cam is huge from what you have so your looking the right direction.

Most of the time when guys do this they go to a Vortec head carb intake and use an adapter to TBI to save quite a bit of money on the intake.
 
For what you're doing I really don't think you need the engine package that you linked to. All you need is the basic L31 longblock. Although you will need to change your distributor gear to the mealonized gear to be compatable with the roller cam. I agree with going with a carb intake and a TBI adapter. If it is within your budget, I would upgrade the cam to the Ram Jet/HT383 cam #14097395. A set of 1.6 rockers would compliment that nicely too.
 
No worries...the motors linked to were Vortec headed, the stock one of course is...and it's a lot of work once you start deviating from stock, so OP just needs to be aware of what it entails keeping injection and changing the engine substantially. Nothing that can't be worked around, just more expense and hassle. Stock replacement drops in and runs as stock, no changes. Anything else, well, starts to get more complex.
 
And use your old distributor with the new motor. The new nylon one is pretty crappy from what I've read.
 
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