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View Full Version : Alky cam -vs- gas cam

358T
09-07-2006, 10:52 PM
I read in a different thread where Jay said an alky cam is way different than a gas cam. Would Jay or anyone else care to elaborate more on this subject??

Let's assume that someone has an race only NA drag engine (things like 14+:1 cr, etc) and changes to alky. What is different in the cam specs assuming the gas cam was optimized for gas??

Scott
Jay Allen
09-08-2006, 10:38 AM
I read in a different thread where Jay said an alky cam is way different than a gas cam. Would Jay or anyone else care to elaborate more on this subject??

Let's assume that someone has an race only NA drag engine (things like 14+:1 cr, etc) and changes to alky. What is different in the cam specs assuming the gas cam was optimized for gas??

Scott
We are talking optimized vs optimized. Max effort.

The alcohol displaces more volume than the gas. There is less room for air. If you want the same volume of air, the cam is typically bigger in duration and tighter in the lobe centers.

Again, typically.
358T
09-10-2006, 03:32 PM
What does that mean in terms of IO, IC, EO, EC?? Depending on where it is installed and the differences in durations it could mean different things.

Thanks,

Scott
Jay Allen
09-11-2006, 07:35 AM
What does that mean in terms of IO, IC, EO, EC?? Depending on where it is installed and the differences in durations it could mean different things.

Thanks,

Scott
The IO/IC is the duration and where they happen is the intake lobe center.

The same is true about the exhaust.

The events need to go further apart making the duration bigger. And the events need to pull ahead to tighten the centers up.

The lobe lift plays a huge key in this as well.

This is as specific as I can get with the limited information being presented.
358T
09-11-2006, 12:23 PM
I understand the relationships between LSA, duration, IO, IC, EO, EC, ICL, ECL, etc. I realize that each specific combo will have different numbers. I'm not lookng for a cam recomendation. I'm just looking for a general answer that covers the typicall changes in the timing events. Agian this is just the typical changes that are made assuming the gas cam was optimized for any particular combo.

For example:

The intake opens earlier but closes at the same time. The exhaust opens later but closes later.

You're previous answer could mean this but at the same time could mean something totally different.

Thanks,
Scott