i own a 97 yukon 5.7, everything is stock except exhaust system, flowmaster cat back system, easy mod.

anyhow, i want to change the motor or have it done, to order a high performance crate engine, where would i go and what would i ask for. i want something with no hassle, bolt in easy engine swap.

 

The key to making any engine modifications work well on these engines is the computer tuning. There are companies like fastchip, and others that to custom tuning. How much power are you actually looking for? Just a light wakeup, or a certain track time or power level? You might consider supercharging also.

 

what is the official name for the engine in this truck? ls?? not sure, and if not recommend me to a place to buy a high perf crate engine. its not out of the question, i am looking for 350 horsepower or better.

just need to know what to ask for when getting it.

 

the 5.7l in that body style is the l31.

 

Use this 383 Shortblock:

http://store.summitracing.com/partde...5&autoview=sku
The only part in the above you cannot use is the timing cover, everything else is bolt-and go.

It will need to be tuned for the increased displacement.

If you are looking for a high-performance true no-hassle bolt in replacement, get a ZZ4 shortblock. Same thing with the timing cover, but this one won't require tuning since it's 350.

 

if he changes from the l31 to a zz4 short block he is really only getting a cam change.
check scoggin-dickey for a crate engine. or you could get the zz383 and install the lt1 hot cam. that should get you @ 425-450.

if you just add the hot cam to your current engine i think you will have retainer to guide interferance.

you could always just add a cam and ported heads.

kevin

 

i would get the fast burn heads work great and do a search someone used 918 for the guide problem

 

Actually the ZZ4 has a forged steel crank, the L31 doesnt.
The ZZ4 has 4 bolt mains, the L31 doesnt (unless its from an over 8600 gvrw truck).

I would get the GMPP shortblock that James suggested and slap on your Vortec heads. Us ethe stock L31 cam if you want a torque monster.

You cant go over 400 hp with teh stock 19 lb/hr injection and intake.
So this means not much cam on the 383. 1 guy I know has used the LT4 hotcam on a Vortec headed 383 and dynoed 330 rwhp with the stock injection. Anything over that and you will need the Marine intake, lik eme and James have. http://www.sfatek.com/images/efi.jpg and use some larger fuel injectors.

Teh Fastburn heads require D-port exhaust manifolds or headers. The Fastburns on a 383 would starve the stock injection for fuel with the stock L31 cam, let alone the ZZ383 cam.
You might be able to get away with Fastburn heads on a 350.

happy shopping
peace
Hog

 

I read that he specifically wants to swap the engine to a high performance crate motor. Not much else was specified. Either of my suggestions are that. Also keep in mind that either one of those shortblocks will spin to 5800 with the stock PCM and better valve springs. The stock L31 is good to 4800 RPM after which power falls off badly. I'd say another 1000RPM of range is "high-performance."

 

hog -- does a 4 bolt main block and forged crank make more hp? i understand there are more differances, but i was referring simply to hp gains.

it is also not specified whether he wants 350 fwhp or rwhp.

james b. -- just add ls6 springs.

regardless, there is still a lot of grey area as to what he wants.
why does he want a crate engine vs. some simple mods?