Intake losses

[Andrew Robertson]

Hi all, got a bit bored today and did a science experiment measuring intake system losses with filters off and on - this was because I'd observed some losses in previous datalogging and I wanted to verify which part of the system was contributing and by how much. Engine is a cammed LS3, induction is EFI 50mm ITBs, test procedure was a quick look for the plod followed by a WOT run from 3k to 6.8k in second gear, which is about 37-92mph. ITBs are fully sync'd and fully opening. I thought the results might be of general interest.

#1 - Filters on, atmospheric reading (Baro) 95.2KPa, Wide open MAP reading 93KPa @ 3k rpm, 88KPa @ 6.8k rpm

#2 - No filters, atmospheric reading (Baro) 95.2KPa, Wide open MAP reading 93KPa @ 3k rpm, 89KPa @ 6.8k rpm

Conclusion: The restriction is reasonably significant (about 4-5%) and is mostly in the intake system itself. 50mm ITBs appear about tapped out at 500-525hp. Upside is punchy/torquey mid range.

Hope all is well!

Cheers, Andrew

 

[Brian]

I like hard data like this. You're filters are a lot less restrictive than what many put on IBTs trying to look cool.

I think you would be hard pressed to not see 5% below theoretical. And truth is, even with a little manifold vacuum, if you have the right length runners for the RPM, you can still get better than 100% VE.

 

[Ian Anderson]

Thread 'Webber inlet flow study'

Jan 25, 2004

Since I am basically snowed in, and recently got acces to a CFD package, I thought I would do a little investigation into the inlet side of everyones favorite form of fuell addition, the webber carb.

CFD stands for Computational Fluid Dynamics, or as one of my proffessors likes to call it, Colorful Fluid Dynamics, because of the pretty pictures it generates. Basically CFD is a way to simulate fluid flow. This can be internal flow, like in pipes, junctions, etc., or can be external flow, like around a car body (hmmm, possible future topic?).

What we are going to investigate is the...

• christian.39
• Replies: 13
• Forum: GT40 Tech - Engines/Induction/Exhaust

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[Jean-Marc]

Excellent, thank you.

 

[joe]

 

[Randy V]

Great video Joe!