Is this worthy of Advanced tech or not? It doesn't really fit the LS1 forum anymore...

flow sheet

 

May not be advanced but I'm glad you posted it. 2.2" intake valve- HOLY COW! 350+ CFM of intake flow- mind bending for a stock head. Mind bending for just about any "small block" head. The exhaust flow doesn't really keep up with the intake in that magic 75+% territory, but still it outflows the INTAKE side of many earlier factory SBC heads!

I wonder if that engine will ever be made in enough volume to be affordable to the average (or above average) hobbyist. I'd love to find out you could dig one out of a junkyard full sized truck a few years from now.

 

It would have to flow that just to keep up with the displacement. Outrageous flow numbers though - another great design by GM.

 

Pretty killer set of heads. Maybe Chevy knows something regarding the 75% ratio. For the most part the power is in the intake flow.

 

The fact that they are using Del West valves and Titanium rods is what surprised me the most.

 

Yeah, the exhaust side doesn't really keep up with the intake. I'm thinking maybe there is physical size limitations on the exhaust side of the head that prevent better flow numbers. Because the exhaust port is really worked from GM. Popular Hot Rodding published the cam specs. GM makes up for the poorer flowing exhaust with significantly more exhaust duration, 211/230. Lift strangly is less on the exhaust side, .595/.588. I don't have an explanation for the lift numbers. Anyone?

 

perhaps the exhaust lift isn't as high because if you run into valve float it is much more crucial to the exhaust valve as chances are it will get hit first, and with that durration maybe GM wants to be extra safe.

Are those stock head flow numbers????

 

Yup 7100RPM red line

http://www.motoring.co.za/index.php?...icleId=2404643

 

I would guess and say there is little point lifting the exhaust valve any higher than that because the port is basically maxed-out at that much lift anyway. More lift would only work the valvetrain that much harder without any power benefit.

I'll bet GM did a VERY careful dance with the intake lift, though. That port obviously just keeps right on flowing better and better the higher you lift the valves. I bet if they could have reliably lifted it .700" without beating the snot out of the valvetrain they would have done it.

 

With the money GM has you had better bet your booties they tried a few different cams and not just with Performance Trends software either.

How sure are the cam spec's? To make 500 hp even with those killer heads and 427 cubic inches I'd say you would need more intake duration. A little bit of lift here a little bit of duration there on exhaust.... doesn't make a whole lot of difference one way or the other.

Only 211 intake duration makes a huge difference. If you made the intake 230 degrees it would probably pick up 30-35 hp and increase the peak hp by 500 rpm.

 

The cam specs were printed in an LS7 article in the April, 05 Popular Hot Rodding. I did mis-type in my 1st post. The intake lift is only.593, not .595.

Everything else was accurate. The lobe seperation isn't listed.

 

The lift is porportional to the valve size.The smaller the valve=smaller lift to get the valve out of the airflow or the curtain area.

 

1racerdude

Trying to figure what you’re saying here. Are you saying a larger valve likes more lift than a smaller valve? Or that higher lift is necessary to overcome some inherent characteristics of larger valves? Or that lift over a certain point with a smaller valve doesn’t help or in fact, may be counterproductive?

I thought what Bret posted regarding Joe Sherman and the engine masters competition was extremely interesting. He chose a cam with what I consider a very modest lift (Think it was like .565??) for the competition using a 2.10 intake valve.

Again….. I’m not a big fan of virtually engine building and my experience is the software that us laypeople buy for the most part is inaccurate. If you play with Performance Trends software, it automatically increases power every time you increase lift. Particularly on the intake side.

I don’t have a handle on the true value or true relationship between valve size or lift and would enjoy some enlightenment. Nor for that matter, how much lift is too much lift and what’s the downside besides valve train wear?

The program penalizes you for larger valves and rewards for more lift regardless of flow. However I see a clear trend these days for putting in larger valves and ya know what….. the cars ain’t getting any slower.

Signed:

Dazed and Confused in Dallas

 

That's pretty amazing for an off the floor package. GM really wants to shoot
down the Viper and re-claim their king of the hill status.

Would anyone happen to have stock LS1 head flow data?

The closet I have come after several searches is:
http://www.tbyrnemotorsports.com/ls1heads.html

How close are the Mongoose #'s to stock?

 

not very...

i think they are in the 240-250ish area, but not postive.