DavidBoren

Would any of the factory rectangle port castings have a distinct advantage over the others for use with a 328ci destroked ls2 quasi-COPO build?

I'm thinking the l92 heads offer the best performance per dollar, but if another ls3 head would be better for a supercharged 5.3 please let me know.

Right now the plan is:
Ls2 block and pistons, genIV 4.8 crank and rods, LSA blower/accessories/cam.

KCS

iTrader: (20)

The LSA heads and a different blower would be more optimal, but it looks like you actually do grasp the concept of performance per dollar.

Dyno Junkie

Tuskyz28

When I saw the title of the thread I knew it was David

DavidBoren

It's still going to have cometic head gaskets. Lol.

But yes, I do understand performance per dollar spent. That's why I'm on an LSx forum, and not a mustang forum.

I was originally looking at the $1800 fully assembled cnc ls9 heads, but I can get the blower AND a set of l92 heads for that.

I know that there are better cams, as well. But I figure the tiny lsa cam would actually do pretty good in a tiny 5.3L engine. Easy on the valvetrain and literally designed for use with the blower I will be using. If I can ever afford to have the blower and the heads ported, then I will get a custom grind cam from Martin.

KCS

iTrader: (20)

I only think the LSA heads are great because of the better casting process and it has more reinforcement around the rocker bosses. The smaller port volume may be good for a smaller engine like a 5.3L as well. You can certainly get away with L92 heads with the solid valves, especially with a stock camshaft. I think I paid about $900 for the L92 heads and LSA blower I got off the classifieds.

I am really curious to see what happens when you put a smaller engine under a PD blower like the LSA stuff.

DavidBoren

I would definitely prefer the rotocast heads and either hollow stem or titanium valves, but I just don't think I can afford it.

The $900 l92 heads AND lsa blower just seems so much more achievable. I can daydream about badass heads and whipple superchargers and not accomplish anything...or I can "settle" for l92 heads and a lsa takeoff blower and actually drive the F'ing thing.

Tuskyz28

Destrokers are nice!!
Here is a cool build that you might like David.

http://www.superchevy.com/how-to/engines-drivetrain/1408-1113-hp-destroked-ls-build-heavy-hitter/

DavidBoren

Any time you mention "destroking" something, it tends to alert the vultures/trolls, and then you have to listen to people **** and moan about decreasing displacement.

I like to think of it as overboring the 4.8L to a displacement of 5.3 liters. Just so happens that GM already offers a block with the "overbore" I desire. Nobody ever bitches about adding displacement.

But thank you for the article. I have read a couple of similar articles on the subject, and I'm convinced that it (the quasi-COPO 328) will be loads of fun.

KW Baraka

iTrader: (7)

We had a couple guys on the Impala SS Forum de-stroke LT1 engines. Didn't make a lot of low-end power....but they were mated to M6 trannys and they rev'ed like crazy! And yes.....they were "loads of fun" to drive!

KW

DavidBoren

I'm hoping that the lsa blower will provide the low end grunt.

I haven't done the exact math yet, but I think that the lsa blower, using the same upper/lower pulleys as the 6.2L lsa, will provide a good amount of boost for the 5.3, being as how it will be feeding a full 15% less cubes.

KCS

iTrader: (20)

Destroking isn't always a great idea NA, but it's not a bad idea with a power adder. The increased crank overlap from the shorter stroke adds much needed strength to the crank and reduces flexing. I was really leaning toward doing the same with the 4.060" iron block I have but it looks like I'm going in the opposite direction *evil laugh*

What I couldn't wrap my head around was whether or not less displacement in a PD blower setup is really a good thing or not. If you have a twin screw type blower where compression takes place in the rotor helix, then it's probably not a big deal. In a roots blower, where the air basically compresses by "backing up" in the manifold, I suspect that a smaller engine gets into higher boost sooner and creates more heat. I dunno, I digress. I'm more of an NA guy to be honest.

DavidBoren

The heat exchanger will be connected to a large reservoir, actively chilled by the a/c, so I'm hoping for the added boost sans the added heat. I know the heat comes with it, I'm just saying I have a pretty good idea to combat the heat.

I chose this combination to hopefully give an awd drivetrain a fighting chance of survival. I figured the short stroke limits torque by limiting displacement, and also delays the torque delivery/production until later in the rpms, where everything in the drivetrain will have a running start to deal with the torque. The rectangle port heads also seem to delay torque production. Rectangle port heads also have cavernous intake runners, and I figured that the large volume runners would be better with the positive displacement blower, being as how it is a volume device. And I chose the positive displacement blower to give back a little early torque production lost by the short stroke, and because positive displacement blowers seem to handicap max power. All of this is beneficial to keeping an awd drivetrain alive at the upper edges of its torque capabilities. Regardless of the short stroke and positive displacement blower, this little 328 is still going to max out whatever the astro/bravada awd system can reliably handle.

Sssnake

Why not just run a boost controller? Throttling the bypass valve should let you roll into the power more smoothly and decrease driveline shock while still maintaining the additional hp and torque offered by the larger displacement. This would also be infinitely more adjustable than just reducing displacement and therefore could be tuned to provide max hp and torque across a broader rev range.