LD340 v/s Edelbrock Air Gap

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mgoblue9798

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Have any of you done flow testing comparing these two intakes with one another? Also interested in Edelbrock magnum air gap as well. How do they compare after a entry level port job? @pittsburghracer
 
mgoblue9798 said:
Have any of you done flow testing comparing these two intakes with one another? Also interested in Edelbrock magnum air gap as well. How do they compare after a entry level port job? @pittsburghracer
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I’ll try to find my flow sheets after a short Power Nap. I haven’t had the occasion to do any magnum testing. All I own are LA based engines and I haven’t had any magnum customers.
 
John may be able to speak better to this but the LD340 has large volume runners compared to the RPM.
I suspect the narrower cross section of the RPM runners better maintains velocity under low flow (low to mid rpm and part throttle) situation. FWIW it has been reported that the RPM made for brand C favors certain runners at high rpm.

I have an RPM to try out instead of the LD340 but never get around to actually doing it....
 
Mattax said:
John may be able to speak better to this but the LD340 has large volume runners compared to the RPM.
I suspect the narrower cross section of the RPM runners better maintains velocity under low flow (low to mid rpm and part throttle) situation. FWIW it has been reported that the RPM made for brand C favors certain runners at high rpm.

I have an RPM to try out instead of the LD340 but never get around to actually doing it....
Click to expand...
The "favoring" of certain runners at different rpms is what all dual plane manifolds are designed to do. Longer runners help lower to mid rpm torque, and shorter more direct runners favor mid to high rpms.
Article writers seem to think the air gap is the end all be all. I am wondering if it is because it is what their advertisers currently have available for sale and whether or not the LD340 can hold its own.

I like that the LD340 can be modified to use a thermoquad for street duty. Just wondering what if anything is being given up using it on a stock stroke 340 or 360 in a high compression build with headers, cam, and a decent set of heads.
 
Mattax said:
John may be able to speak better to this but the LD340 has large volume runners compared to the RPM.
I suspect the narrower cross section of the RPM runners better maintains velocity under low flow (low to mid rpm and part throttle) situation. FWIW it has been reported that the RPM made for brand C favors certain runners at high rpm.

I have an RPM to try out instead of the LD340 but never get around to actually doing it....
Click to expand...


For sure on the runner size. No dual plane is easy to port and in one split second I can break a 25.00 cable on my Foredom grinder are bend a 50.00 burr. But there for sure is more space in the runners compared to an Airgap or especially a Speedmaster intake.
 
mgoblue9798 said:
Have any of you done flow testing comparing these two intakes with one another? Also interested in Edelbrock magnum air gap as well. How do they compare after a entry level port job? @pittsburghracer
Click to expand...


Ok the only two LD340’s I’ve tested was this one I just did and the one I reposted the link to in 2012. I have some past Victor340, old school Torquer intake, and RPM that I can post up. The only problem is was this customer was going to be running a TrickFlow head so I grabbed mine to test on and found two bad ports. One was so bad I couldn’t use it at all so I unbolted the head and moved to another runner. It was bad too but good enough to test with. Trouble is with the head not being right it affects the intake numbers. I hope you can get some info from these.
 
Ok here’s a stock TrickFlow head tested with a stock Victor340 and a ported Victor340. You can see where the TrickFlow head stalled and it in turn stalled the intake.

IMG_0087.jpeg
 
pittsburghracer said:
Stock TrickFlow head with issues and a stock RPM then ported RPM intake.

View attachment 1716157960
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This is why I try to talk guys out of shipping dual plane intakes to me. Do I believe they will work better??? Yes I do. But if I charge someone 300.00 and they spend 150.00 dollars each way shipping it to me I can’t justify the gains for the money spent. Now in
Chris’s case with an LD340 I cut him a little price break because he’s patiently waiting for me to port his heads. He’s also limited to that intake so horsepower gained is horsepower gained. He is also taking a road-trip to Pa to pick up his heads and intake saving me a lot of packaging.
 
pittsburghracer said:
This is why I try to talk guys out of shipping dual plane intakes to me. Do I believe they will work better??? Yes I do. But if I charge someone 300.00 and they spend 150.00 dollars each way shipping it to me I can’t justify the gains for the money spent. Now in
Chris’s case with an LD340 I cut him a little price break because he’s patiently waiting for me to port his heads. He’s also limited to that intake so horsepower gained is horsepower gained. He is also taking a road-trip to Pa to pick up his heads and intake saving me a lot of packaging.
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Have you done a stock speedmaster air gap intake vs a stock Eddy air gap ?
 
pittsburghracer said:
It was real small runners compared to the LD340. The price was right during the 40% off sale but I wouldn’t buy another one.
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I was thinking SM vs the Eddy RPM air gap .. but I'm sure the RPM would flow more as well. I think the SM intake (I've used 2, have another new in the box still) is great for a stock or near stock engine. A great, cheap way to put a carb on a magnum, or a 4bbl on a LA. But I do not think it's the intake of choice once you start North of 400 hp
 
Mattax said:
I suspect the narrower cross section of the RPM runners better maintains velocity under low flow (low to mid rpm and part throttle) situation.
Click to expand...
I agree. I noticed a difference in plug colouring on the Weiand stealth manifold that has the large variations in runner CSA between plenum sides.
 
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