I see Scoggy has a project car for sale on a thread here and it has a 408 with lots of good parts but is running 5.3 heads.

Why 5.3 heads?

Do I have some sort of magic weapon that I didn't know about?

 

Nothing wrong with 5.3 heads as long as they are ported and capable enough to support the 408s cfm requirements...

 

Ok.... nuttin wrong w/5.3 heads but what's good enough about them that they, with all their $$$ and best parts available would build their project truck with 5.3 heads?

I'm especially curious because my plan was/is to put 6.0 heads and a cam of some sort in my 5.3 this winter... while I gather parts for the 6.0/4l80E swap next year. I plan to take a community college head blueprinting and porting class and then an engine blueprinting and performance engine building class this winter and next spring so I can actually build my own engine. Building my own engine is a goal I've had for many years. Fun stuff. Pretty cool feeling to build an engine and then hear it come to "life". (had a new granddaughter "come to life" this weekend.... speaking of cool stuff!!!)

But more to the point....... if a performance shop is using 5.3 heads on their shop project truck then maybe I need to find out what's up and what I can do to mine. I suspect that maybe the 5.3 heads lend themselves to producing torque?? while maybe the 317's are better for hp but maybe lose some torque???

What say you engine builders? Richard @ WCCH???

 

I'd assume that the reason they would do it is to get a certain compression out of the motor with the pistons they had. The smaller the combustion chamber the lighter the piston to achieve the same ratio. A reverse dome piston can save some weight over a flat top sometimes, pending on piston construction of course.

 

I was thinking compression too, alot of the ls1 guys put them on there firebirds/camaros. I know by putting 6.0 heads on a 5.3 you will loose compression so take that into account.

 

Confusion runs rampant. That essay/paper that has been online regarding Gen III engines says that 4.8 5.3 and 6.0 heads all have 71cc chambers. I think I read somewhere else that the 5.3's have 61 cc heads and the 6.0's have 71 cc's. So it makes sense that the 5.3's would, with porting, make good heads for the 408 in the project truck.

I guess I'd want to keep my 5.3 heads while I build the 6 liter engine. I still need a cam. I think the Lingenfelter made for the Radix will be the one for me.

 

You've got my interest up on cc's. I've got a set of 5.3's and a set of 6.0's in the shop. I'll cc them tomorrow. I have some plexiglass and the measuring devices already set up for it. The 6.0's have to be bigger from what little measuring I have done.

 

Hey jackass so when I was asking about the cc on the 5.3s why didnt you do that. Dont screw up either set of MY heads or have you finally decide to use the 6L heads like I told you, you should?

 

I'm going to use the 6.0 heads *******! I figured you would have just asked someone else. It was much easier. Either that or I was in the process of getting another beer and didn't hear you!

Here is the test.
5.3 & 6.0 head cc test

 

I think im confused now, i think we agree on this though...5.3 heads on 5.7 or 6 liter will raise comp because of combustiion chamber size, just how the 6.0 heads drop comp, which is why many 5.3 guys puts 6.0 heads on there FI 5.3s