My fluid dynamics courses are coming back to me!!!

Great thread btw!

 

Any further testing with aftermarket bridges/couples?

 

True enough, this was an informative thread thought there would be more testing going on not much action lately.
Motivated me to drill 4- 1.75" holes in my stock lid and use a foam 3 stage filter, slightly more intake noise but I felt a seat of the pants difference from my restricted lid on my 2000.

 

IMHO - RedHot showed minimal difference in flow gained by going with a different filter material (i.e., K&N vs. paper) and based on tests done by an individual on air filter materials (similar to what RedHot is doing), he showed that there is a considerable amount of dirt that passes through a fabric (K&N) filter or a foam (e.g., Amsoil) filter when compared to a stock air filter. You can link to the air filter tests through bobistheoilguy dot com site. (FYI - I threw away 2 expensive Amsoil filters after digesting the test information). For the amount of gain, it would appear that the dirt ingestion increase wasn't worth it. Like I said, just my humble opinion based on the information I found available on the Internet.

Exhaust Side Question

Kudos, RedHot on the information gained. Thanks for sharing. Confirms my gut instincts. (FWIW, I think the Vararam (and similar) primarily increases power by lowering intake air temp, not by forcing air into the intake...this has been beaten to death in the past) I note that the V.E. used to calculate the flows on the LS1 were 100%. For those that might not know, the actual V.E. of a NA engine decreases as the RPM's go up. It will be around 80% at 5000 RPM and 75% at 5500 RPM for a Chevy small block V-8, depending on intake, cam, head porting, and exhaust design. Decrease the CFM through the intake assembly accordingly for total flow through the engine/air intake (for example, if 500 CFM for 5000 RPM at 100%, in actuality it would only be 400 CFM at 5000 RPM, all else being equal). Header, head, cam and intake design become more important as engine speed increases, in effect, the scavenging capabilities.

That's where this exhaust question comes in for RedHot.

It appears you may have done a lot of flow studies on heads, too??? Have you looked at header/head combinations? I'm curious about the gains one could realize by trying to port match these 1-3/4" primaries to a stock head and what the best way would be to do that. As it appears to me, there's a huge x-sectional increase between a stock port and the 1-3/4" inch primaries in the aftermarket headers which will result in an instantaneous reduction in exhaust velocity and the change of velocity to pressure, i.e., a pressure increase at the exhaust port (which is exactly what we DON'T want). From fluid dynamics, dynamic losses can be expected as the velocity pressure changes to static pressure. Any data or thoughts? My guess is that the header port should be the same size and shape as the head port and then slowly transition to the shape and size of the primary tube. But actual data to show if it were worth the effort to build a header like this.....well, that would be worth lots....or even inserts that fit into the header but transitioned from the exhaust port shape to the round diameter of the primary tube. Thoughts?

And you thought your earlier post was long winded



TopCat

 

Redhotz06; How about a flow test with and without the MAF screen in place....must be some restriction there... or did I miss something in your posts?? Thanks, Dave

 

Topcat,
For what its worth, I agree with you and stopped using a K&N in my Z06 and switched back to paper. But last year, AMSOIL came out with a new filter line that filters extremely well without sacrificing flow and I switched to this: AMSOIL Ea Air Filter
C5 part: EAA83

 

As Elmer Fudd would say, "Vewwy interwesting."
Gotta love that nano-tech stuff!

 

I plan I getting the Z06 lid but where do you drill the holes- lid or box- and then do you have to seal the hood?

If it wouldn't be to much trouble would you flow test a couple of components at a lower pressure to see if the flow curve is linear. Just a thought.

I am a retired test engineer who spent 19 years working in gas and fluid flow testing.

FYI- on production test stands we mounted the throttle body, plugged in the throttle position sensor, connected to the throttle shaft with a servo motor, and shot the throttle plate with a laser gage.
The test was to verify flow at various throttle positions, check the accuracy of the throttle position sensor.

 

Why don't you just drill out your stock lid, the Z06 lid has a slot on the front which let's more air in than a stock C5 lid but if your drilling holes anyway it shouldn't matter which lid you use.
I'll see if I can take a pic of mine.

 

I just ordered the K&M filter for my 98.....now I read this....

 

Hey Gordy M, can you elaborate on what the LS1 engineer told you? Why would a silicone coupler collapse at full throttle? What would the shape of the airbridge would have to do with the adaptive capability of the ECM? Just curious, thanks.

 

RedHotZ06, are you interested in flow testing some stock Z06 Cats versus some high-flow aftermarket metal matrix cats that usually come with all these long tube header setups that everyone runs? I have some.

Also, anoterh question: You mentioned in a previous post that a 346ci engine at 100% VE and 6000rpm would need 600cfm of air (at pressure drop of 10" of water, I assume). The 2.5" cats sold by Random Technology flow 483cfm at 28" of water. So, I assume that means that if you have dual Random 2.5" cats that your cats can flow a total of 966cfm at a pressure drop of 28" of water. If all that is correct, then what is the flow rate of these cats at 10" of water? If this exhaust flow rate is above the 600cfm of intake flow rate, then is it fair to assume that the exhaust is not a bottleneck for the engine?

thanks!

 

Excellant thread, thank you for all the hard work!!!!!!!!!

 

Paul, great thread, Thanks for sharing. Just ran across this post today.
Paul, have a question on what was temp. at the time the test were taken. And what would the flo rates be, saying the temp was increased by 50 deg. Being less dense air. Compaired to pulling outside air. or air from under the hood. Thanks Jerry

 

Excelent Info here. Have you had the chance to complete any of the additional tests mentioned?

 

I do not understand Paul
So no lid and no filter = 409 cfm but if you add a z06 lid with holes and filter you gain 50 cfm ?

How is the lid and filter going to give more cfm as opposed to no filter or lid????

 

The lid and filter will act to smooth the air flow. Without significant turbulance is created reducing air flow.

 

does the velocity stack do anything?

 

I just took my whole air box out, I live in South Florida and never had a problem with the rain getting in so far. It is amazing the difference on a cool night especially on the highway.

 

restriction is too small to make a difference. You actually harm performance removing it. The maf sensor does not operate accurately with the removal.

If it has been already proven that larger throttle body are worthless on a other wise stock car then removing the maf will not help you for sure.


just fyi