SS 5.3 ls combo

[JRyan]

Don't know about the block situation. But the heads flow great. We've had a couple sets on the bench that we've done flow over 300cfm @.700 without getting really crazy with them with the stock size valves. Could be a pretty interesting combination I think.

Rick

[Bryan Broaddus]

Removed

[Henry S]

I think the aftermarket block would be my choice on this build. and the heads have great potential. I am just not sure if the throttle body can support the airflow demands. Maybe a sheet metal intake can overcome the throttle body size. I would like to see the motor make between 680 to 700 hp. I think the heads can support that, the question is the other components. I think peak power may be in the 7800- 7900 range.

[Mike Taylor 3601]

If you are talking 300@28'', if throttle body and intake don't cut back air flow, I calculate around 611 HP @ 8759 rpm, this is calculated using superflow's formulas for HP and peak rpm for HP based on airflow and cubic inch.

Mike Taylor 3601

[Henry S]

Thanks Mike, I forgot about those calculations. I have used those in the past and I have found that you may have to multiply the horsepower by the volumetric efficiency to get close to real world numbers. The rpm side was usually close. I didn't think with the longer stroke of the 5.3 that it would need to rpm that high.

[Dwight Southerland]

Originally Posted by Henry S

I didn't think with the longer stroke of the 5.3 that it would need to rpm that high.

You're kidding, right?

[Mike Taylor 3601]

Those formulas make real world numbers on the superflow I use,stock configuration heads using stock valve locations and angles about 99% of time will make within 5 hp of formula.
When you get into raised runners,18 degrees etc, spread ports,big chief style etc. then they make more than calculated.
LS engines I don't have any dyno info on them,don't know if will just make calculation or more.
I always check head on flow bench when I know I will run a engine on dyno,so I know what hp to expect.
as example a small block i had heads went 275 @ 25'' calculates 594 made it made 596.

Mike Taylor 3601

[Adger Smith]

Mike,
I have found the LS heads make more power than the formulas for traditional heads. More like RR and spread port heads. I have a fudge factor when doing LS engine models. I believe his concerns with the T-Body air flow are justified, but not as important as with traditional heads. I've never done a carb or injected restricted LS engine. The closest I done to a restricted one is a 5.7 bracket deal with a good 750.