Varioram 101 - How It Works

[Mike Feinstein]

For those interested: http://instant-g.com/Products/36Conversion/VRAM.html

Compliments of Dr. Timmins. I have been burying the poor guy with questions and he has patiently answered every one. He just sent me this link and I attach it here FYI.

Enjoy,

[Bill Verburg]

Thanks Mike!

[widebody911]

Interesting - he sez the 10hp is due to the larger valve size - not the VarioRam. So does the VarioRam bit add any HP? It seems it would, but what do I know...

Steve is an amazingly patient guy.

[Bill Verburg]

The v-ramallows the low speed torque to be enhanced, the valves enhance high speed torque, hp is derived from torque therefore also enhanced, displacement enhances torque across the board.

RS has even bigger valves

[widebody911]

Originally posted by Bill Verburg
RS has even bigger valves

It's not the size of the valve that matters, it's the... oh hell, it's the size of the valve!

My browser hadn't finished loading the table at the bottom, hence my seemingly silly question...

[Bill Verburg]

A little extra lift and duration don't hurt the top end either

[beepbeep]

Well extra torque at lower revs will certainly help in-gear accelleration, even if it doesn't yield more horsepower at the top.

[tholyoak]

While on the subject of intakes, another interesting observation is that on the early 964 with the magnesium throttle housing and cast manifolds the throttle body actually contained 2 plates as shown below



but on the later 964 (and pre-Varioram 993) with the plastic center section and manifolds and bolt on throttle body it was a traditional single butterfly:



Any thoughts on this??

Todd

[john70t]

Great link Mike!!

Umm..definitly not an engineer...wild guess in the dark but:

The early version used dual butterflys to keep the manifold pressure up in order to help low end torque (something about keeping the transition of vacuum pulsations to the intake runner consistant to get high air flow through a smaller diameter pipe) and the duel intake runners later expanded on this(?).

The second generation was a realization the dual butterflys were a restriction so a larger idle air bypass valve was used(?).

[Bill Verburg]

The early version used dual butterflys to keep the manifold pressure up in order to help low end torque (something about keeping the transition of vacuum pulsations to the intake runner consistant to get high air flow through a smaller diameter pipe) and the duel intake runners later expanded on this(?).

i didn't know that, thanks for posting

I do know that for any performance update you want the later one or a 993.