I had a customer drop off one of Richard's L92 heads from West Coast Cylinder Head along with and L76 intake and a prototype sheet metal intake that he may market. I thought I would post the flow sheets and photos of the sheet metal manifold.

I flowed the head first with a radius plate, then with the L76 manifold followed by the sheet metal manifold. The exhaust port on this head flows quite well. Note that I used a fairly large straight tube on the exhaust port to straighten the flow.

The flows that matter are the flows through the intake and the flows with header attached. That is what the engine sees in operation.

I'm going to recommend a few changes to the sheet metal manifold. The plenum can be made larger and the runners can be made slightly shorter. As is the runners are 6.5" long giving an opening to valve length of 12". The L76 manifold has a runner length of 12.5" resulting in an opening to valve length of 18".

This L92 head flows almost with an LS7 head through the manifold. I tested an LS7 head a few months back with the LS7 manifold. I attached a comparison graph comparing the L92 with the LS7.

The L92 as ported by West Coast Cylinder Head has 2.160" intake, 1.602" exhaust valves, 265cc intake runner volume, 99 cc exhaust port volume and a chamber volume of 72.6 cc's. I did not CC the intake on the LS7 head but it was stock factory CNC ported.

 

Nice info, thanks!

 

Great work. I'm loving my WCCH L92's from Richard. Now we need an intake for the street that will fit under the hood of a C5.

 

That is a much appreciated project!

 

Thank you for sharing this data Steve.
I tend to agree with you about the plenum size and perhaps the runner length. I'd like to know what the runner cross section is just under the radiused entry.
Any idea if when this intake will get tested on an engine?


Richard

 

Richard,

The runner appears to be formed from 2.25" aluminum tube about .050" thick. So the ID at the runner entrance should be somewhere around 2.150". There is no way to get inside to measure any better.

There is some taper in the runner but not as much as I would like.

I don't know if Mark intends to run this manifold on his engine or if he brought it over for me to take a look at and test. I did an LS2 dry sleeve block for him for his 427 which your heads will be going on. I'll ask him what he intends to do when he picks up the block.

I need to take a run up and see you one of these days.

Steve

 

Thanks for adding the info on the runners Steve. I'd like to see this intake flow a bit closer to the port only flow curve. There must be a pinch point somewhere in the plenum/runner entrance or the runner itself. Still it's a nicely fabbed intake and no doubt will make for some nice upper rpm power.

You're welcome to come by anytime. If they'd ever cut my chain loose I'd like to stop by your place too........

Richard

 

Thanks for posting, Steve. I think we both had some ideas for improvement on the sheet metal piece, this was the first physical testing on it to my knowledge. Another knowledgable colleague of mine had similar ideas on some moderate changes. Nice to see the comparison with the L76 plastic piece, obviously the hopes were a bit of a more dramatic improvement.

Richard, I had intended to send this piece up to you as well, just a bit swamped and it never trickled up to the top of the to-do list. I intend to put this on my 70 Camaro, as Steve mentioned, he did the major block work for me so it'll come together a bit faster now, but the car is lagging big time (being held hostage in the paint shop), so it's going to be a short while before it's pounding pavement. Having very little patience as a personal virtue is not helping my mood! Now that we have specific flow numbers though, it's basically time for you guys to recommend the cam(s), so with all of your free time (joke), might be worth thinking about in the back of your mind.

Mark

Edit: spelling.

 

I think it's a good starting point and you've gotten some good quantified information here. I'll be interested to see how this evolves.

 

I thought the article below was interesting, it seemed to say that the compression wave is reflected into the runner off the opposite plenum wall (such as a round tube plenum). Is runner length and plenum volume the only factor? Wouldn't a pressure wave from an intake valve closing reflect off the plenum wall?

I also always wondered why intake manifolds were not more like headers, I thought it was odd that runners don't point towards the throttle body. I've also wondered why plenums didn't taper down away from the throttle body. The whole thing about how air makes a 90degree turn into a runner at 90mph just doesn't compute in my little brain, especially when looking at the last pic you posted looking inside the plenum. Obviously I have no idea how airflow works, otherwise all plenums are 'wrong'.



http://uanews.org/cgi-bin/WebObjects...KI7X2ksS2jlCa0

Senior Design Project Squeezes 50 Extra Horses from a Mini Cooper Engine

By Ed Stiles
May 11, 2006

..."Depending on the length of the runner, the wave gets reflected back at a certain time," Crozier said. "So you want it reflected back at precisely the time when the valve opens, maximizing the mass flow into the cylinder head. Power is optimized in a particular rpm range, based on the runner geometry and length."...

 

This is an interesting thread. Good info to have saved.

 

Thank you very much for this information. Man how good is that factory L76 intake?