I called comp cams when I was building this yet told me to use the beehive springs so thats what I went with

 

Did anyone consider the fact that maybe the dyno operator let off early?

 

Its seems that the dyno operator shut off at 5800rpm when the power decreas.
Well its hard to see whats going on.

The beehives should do the job if they arnt broken.
Its hard to see whats realy going on graphs you show.

 

Well you have to assume that the dyno operator have the knowledge or talk
with the customer who hopefully knows at what rpm you approximately see
the peak rwhp.

 

Have it leaned out to 12.8-13:1 air fuel and it should pick up a bit.

 

Looks like you need to rev it out further to be sure its not just falling off. Graph should extend a good ways beyond peak hp with that cam. Should pull to well over 6300 rpm so I'd try again and see where that gets you. Does look like he let off early.
Nothing wrong with the combo of parts, it just may need abit more tuning/rpm to see if that helps, then move on to other things. Maybe play around with the cam advance to see if that helps anything. The heads may need abit more work to get more power. Abit larger valve size would help. Good valve job would work too

 

LT1 heads don't like outdated bigger is better, valve thinking. Many of the most powerful LT1 head setups out there use 2.00/1.56 valves. Like 9s NA with GM casting heads and intake.

 

That may be the case due to small LT1 factory casting chambers, but alot of powerful sbc's in the same bore size respond well to 2.02-2.08 valves. Its all in the head port and cam details. And its not "outdated" Not sure where you get your information from. Look at all the other sbc heads and aftermarket LT1 heads. Bigger valves Once you get into ultra high lift cams in race applications, you need more valve to pass air flow required.

edit: AI's claims of 530whp I thought was misleading for 138 mph but I realize that is a 5500 stall unlocked converter which never put down true numbers like a locked converter or 6 spd car. They are doing well with a 2.0 valve, but switched to TFS heads with 2.08's i believe and he went mid 9's Making more power with more air from more valve. Casting is different. I'm sure with some work you can get abit better results with abit larger valve on stock castings.

 

Apples to apples. For stock castings, a 2.0" - 2.02" valve is just fine. My 383 seems to be doing just fine with 2.0" valves and 560fwhp.

And the OP is only looking for 20whp - a bigger valve won't deliver that.

 

Thats hard to say...Just by itself a larger valve doesnt mean more power/flow. You have to look at the entire port, and shape it to work with the valve. Whoever did the porting could have messed up the port. The velocity profiles could be all wrong, it may be going static at some lift point, etc. We dont know, we dont have information on the heads. To correct the port shape, it may actually need the larger valve and different bowl/throat dimensions and seat angles to go with it. It may not, impossible to know for sure.

Its likely he just needs to optimize cam events to work with the heads he has but he would need flow data for all the lift points and also look at the velocity profiles. Custom cam matched to that setup likely can find another 20hp.

Like I said above tho, AI is doing well with 2.00 valves, and just about every AI setup i see over the years have made great numbers and ran great times. You cant go wrong with a proven setup.

 

The mid 9s setup also uses a completely different intake manifold. How much power came from that?


The GM LT1 heads don't seem to want any more than a 2.00 valve, if an aftermarket casting does then fine but that isn't what we were talking about. Many have put 2.02 valves in LT1 heads some even put in the bigger seats necessary to open the throat right, they haven't run convincingly though.

 

Good question too, intakes make alot of difference in some cases. Could have been a combination of things, but going from high 9's to mid 9's takes alot of power. More so than going from mid 11's to low 11's lets say or even high 10's to mid 10's. Some of that was in heads. Some in the rest of the combination

 

Corey Harris, semed to do agreat job in the tuning of this. Where is he located?