VMP 67mm vs 69mm Throttle Body

[CD07GT500]

Yeah...that is also correct. My point is that the VMP67MM is within a very close margin in cfm potential to the larger monoblades, which is impressive. A rep at VMP made 1088whp with a 67mm but explained that in the context of my application the 69mm is meant to be for guys who dont want to run a monoblade but want the same flow characteristics. The monoblade has its advantage and he even admitted that the twin could be a restriction as his power level. For me, I'm not making 1000 wheel, so the point is moot for me.

My point is the twin 67 becomes a restriction well before 1000 wheel. In fact the restriction starts well before 700 wheel and they are not close in CFM.

 

[CaliGT500524]

My point is the twin 67 becomes a restriction well before 1000 wheel. In fact the restriction starts well before 700 wheel and they are not close in CFM.

Yeah maybe, but there appear to be a ton of folks that run the 67mm with closer to 800 wheel, more so than those who find it to be a restriction at 700 wheel.

I have seen several folks quote flow tests that indicate the VMP being within only 50cfm to some of the monoblades. That's pretty darn close. More than just about size, that TB has a different port design and shape.

 

[CD07GT500]

Yeah maybe, but there appear to be a ton of folks that run the 67mm with closer to 800 wheel, more so than those who find it to be a restriction at 700 wheel.

I have seen several folks quote flow tests that indicate the VMP being within only 50cfm to some of the monoblades. That's pretty darn close. More than just about size, that TB has a different port design and shape.

They become a restriction well before 700. Here is a 11 GT500 with a basic Gen 2 2.3 TVS combo. It picked up ~25hp same day, same dyno, same conditions, with only a t/b data change in the tune.
Twin 67 vs CJ mono

 

[CaliGT500524]

Buy a 67 and call it a day. It is proven.

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OK, but is that still the case if the 67 and the 69 are the exact same price? That is my dilemma, I may also some day upgrade the blower but am not certain.

 

[Catmonkey]

I have seen several folks quote flow tests that indicate the VMP being within only 50cfm to some of the monoblades.

Don't believe everything you read on the internet. VMP made a 72mm at one time that was supposedly a stones throw from the CJ monoblade flow rating. I'd speculate the 67mm is a good 200 cfm shy of that. There's a lack of credible cfm data out there, and even then they aren't necessarily at the same pressure differential. Kenne Bell claims the OEM 60mm twin, the CJ 65mm and the CJ momoblade measures 1,128 cfm, 1,322 cfm and 1,701 cfm, respectively, on their flow meters. KB claims 1,850 cfm on their own 75mm twin. Just interpolating the data, I'd estimate the 67mm and 69mm at approximately 1,400 cfm and 1,500 cfm respectively.

To put all that into perspective a 2.3 TVS with a 2.4" upper and stock lower would pump 1,442 cfm at 6,000 rpm if it were 100% efficient. Typical cfm formulas for a 5.4 will compute a 1,156 cfm requirement at 200% volumetric efficiency. The fact remains bigger throttle bodies usually make more peak power. It may have more to do with the air flow needing to turn ~120 degrees from inlet to rotors than actual air flow requirements. But there comes a point of diminishing returns. 10-15 hp at peak doesn't mean a great deal if fail safes and/or drives like crap.

 

[VNMOUS1]

OK, but is that still the case if the 67 and the 69 are the exact same price? That is my dilemma, I may also some day upgrade the blower but am not certain.

Bigger isn't better.

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