School Me on LS Motors

[OutlawDrifter]

I found this article the other day. It's a bit old, but it narrowed my search a bit.

https://helpcenter.jegs.com/hc/en-us/articles/115012012407-Junkyard-LS-Engine-Builds

Our prime candidates for engines are LQ9s or LY6s. Currently our goal is to keep the bottom end stock and unmodified other than new bearings and ARP rod bolts. The LQ9s have a 10.0:1 compression ratio. The LY6s have a 9.67 compression ratio, but came from the factory with the L92 heads. The L96 is also a contender, but it's newer and harder to find cheap.

Actually finding the engine is another matter. I'm going to have to beat the bushes and pester friends to see if anyone knows of an engine for sale. Here in Oklahoma it's a seller's market for trucks and truck parts. Complete engines with harnesses and accessories are $1500-$2000. The heavy duty trucks that have these engines command a premium, even wrecked.

LQ9's have ALWAYS drawn a premium. Fastest way to build an iron LS2. LY6 will have the added cost of deleting VVT if you're not intending to keep it.

 

[RDF1]

I would go for the LY6 or L92 engines with the 821 heads. THey flow better with rpms than the 317s of the LQ4/LQ9 heads.

Do you have a budget in mind on this project?

 

[RDF1]

LQ9's have ALWAYS drawn a premium. Fastest way to build an iron LS2. LY6 will have the added cost of deleting VVT if you're not intending to keep it.

They wouldnt use the stock cam so its just a timing cover and a sprocket to delete VVT.

 

[Erik the Awful]

L92 heads are the plan, no matter the bottom end. They're the only affordable head that might get us in the 650 hp range.

An LQ9 would be the ideal bottom end because it has 10.0:1 compression ratio. The LY6 has nearly as much compression but comes with the L92 heads.

The L92s are aluminum block and command a premium, so they're out of consideration.

They wouldnt use the stock cam so its just a timing cover and a sprocket to delete VVT.

I haven't really studied the VVT delete yet, but yes, if this comes to fruition we'll absolutely be calling a cam company and ordering up something tailored to purpose.

 

[L31MaxExpress]

L92 heads are the plan, no matter the bottom end. They're the only affordable head that might get us in the 650 hp range.

An LQ9 would be the ideal bottom end because it has 10.0:1 compression ratio. The LY6 has nearly as much compression but comes with the L92 heads.

The L92s are aluminum block and command a premium, so they're out of consideration.


I haven't really studied the VVT delete yet, but yes, if this comes to fruition we'll absolutely be calling a cam company and ordering up something tailored to purpose.

The rectangle port heads have larger chambers hence the compression drop on the newer engines compared to the LQ9.

 

[RDF1]

L92 heads are the plan, no matter the bottom end. They're the only affordable head that might get us in the 650 hp range.

An LQ9 would be the ideal bottom end because it has 10.0:1 compression ratio. The LY6 has nearly as much compression but comes with the L92 heads.

The L92s are aluminum block and command a premium, so they're out of consideration.


I haven't really studied the VVT delete yet, but yes, if this comes to fruition we'll absolutely be calling a cam company and ordering up something tailored to purpose.

Talk to Martin Smallwood about a cam. Just have all your info for him to figure out what you need.

 

[Erik the Awful]

The rectangle port heads have larger chambers hence the compression drop on the newer engines compared to the LQ9.

From what I'm reading the LQ9 heads have 71cc chambers while the L92 heads have 68cc chambers.

Talk to Martin Smallwood about a cam. Just have all your info for him to figure out what you need.

We're nowhere near that point. This is still a pipe dream at the moment.

 

[RDF1]

From what I'm reading the LQ9 heads have 71cc chambers while the L92 heads have 68cc chambers.

Ive measured 317 heads from 70.3 to 71.8cc and also 823/821s from 68.0 to 69.3cc. So they are pretty close.
Now the 243/799 heads have a 64cc chamber so those on the LQ4/LQ9 help with compression. But wouldnt use them for a higher hp N/A Setup.

 

[L31MaxExpress]

Sorry gentlemen, I stand corrected. Perhaps the sole set of 317 heads I have had my hands on in the past had been previously milled on as they were about 66-67cc. The LQ9 I had also had pistons about 0.005" higher than the block deck surface.

 

[RDF1]

Yea prolly milled enough to get a good surface. and .005 is normal for Piston out of the hole.