head flow numbers.

[gtxrt]

not sure why the flow went bad after .300 lift. the stock intake valve was 1.87 new one 1.94. want to get another 10 cfm after .300 lift. with a stock intake valve on stock heads they make 190 cfm at .500 lift.

 

[vance.dykes]

carb spacer ?

 

[pnora]

They obviously are restricted. Need to talk to the Buick gurus.

 

[gtxrt]

carb spacer ?

am not worried about flow with the intake on.

 

[gtxrt]

They obviously are restricted. Need to talk to the Buick gurus.

heads are heads. not trying to get high flow numbers just inline with the low lifts.

 

[pnora]

Quick google search.

 

[gtxrt]

looks like Koffel was a better nail head porter then the nail head porters

 

[gtxrt]

looks like the 400 lift is good just after that gets bad.

 

[pnora]

looks like Koffel was a better nail head porter then the nail head porters

Could be. Flow benches just like dyno's have been known to vary from shop to shop. Porting is a science and some porting can take away if not done right.

 

[gtxrt]

just weird how it nose dives even going down at 550 lift.

 

[pnora]

just weird how it nose dives even going down at 550 lift.

If the head can not flow it most likely creates a turbulence imbalance is my best guess. The intake could very well play into it. The numbers show that there is a flow restriction or corruption of flow with the intake.

 

[RemCharger]

It's a low performance, low rpm motor. No surprises with the low flowing ports .

 

[gtxrt]

It's a low performance, low rpm motor. No surprises with the low flowing ports .

they already been ported with bigger valves the flow numbers are good to .400 lift. koffel get the right numbers

 

[pnora]

they already been ported with bigger valves the flow numbers are good to .400 lift. koffel get the right numbers

Koffel's numbers are someone else's porting and a different flow bench. So send your head there and see if his numbers are different than what you have now.

 

[PRHeads]

Aaahhhhhh yes…….. racing flow benches.

 

[gtxrt]

what ever flow bench the .500 lift above numbers will never be good

 

[gtxrt]

wondering if the intake valve just needs to be more un shrouded. the exhaust numbers are good

 

[gtxrt]

Aaahhhhhh yes…….. racing flow benches.

any advice ?

 

[PRHeads]

But……if the numbers were in the 220-230 range, would you still be worried about it?

I had some heads here not long ago that had been ported.
I had flowed the heads on my bench before they got shipped off to be ported.
The post porting numbers supplied by the porting service showed nice gains thru .700 lift……with a significant jump in flow from .600 to .700.

When I flowed them after porting, the big number was over 10% lower than the supplied numbers, and they stalled at .600, and slightly dropped after that.

If you carefully compare the Koffels numbers…….to pretty much anyone else’s numbers, for most any cylinder head running a similarly sized valve(1.94), you’ll find something that raises a red flag(for me anyway………and is something I have never come across in flow testing heads for 32 years).

 

[PRHeads]

any advice ?

I have zero experience with those heads.
But my suggestion is see if there is consensus as to whether or not the numbers you have for your heads are close to “normal” for that level of work.