Questions About Compression, Domes, and Head

[MJohnson3764]

Im looking to do a few things to my Banshee over the winter and I've been researching and asking around and I think im closing in on what I want to do to it.

 

I was looking at get a timing plate and setting it to +4 for more low end power. I've been hearing that setting the timing plate can cause you to have to change the octane of fuel that you use. Can anyone explain to me what octane it might require with these addons?

 

I'm looking at getting vForce reeds, I dont think that will really affect fuel type right?

 

And I'm also looking at getting a Noss Cool Head and as for the domes thats where most of my questions are. Jeff from FAST Toys suggested a 20 or 21 cc dome. I looked my elevation and it is just about 300ft above sea level. With the timing plate and head and dome, what octane of fuel would I need to run at? And can anyone explain to me what exactly the domes do and what the different sized domes do. Like what would be the difference between at 18cc dome and a 21cc dome?

 

So the basic rundown is

 

-Timing Plate +4

 

-VForce Reeds

 

-Noss Cool Head

 

-Looking at possibly 20-21cc domes

 

300ft elevation

 

Thanks guys

[2001Stroker]

A basic rundown, 18cc domes are for higher compression. 21cc is for lower compression. The cc number is basically for how much volume is in the dome. More compression will help give you a better low end torque, but will lose some top end. More timing will help alot down low, but will also help some through the entire rpm range. Yes, you need more octane for higher compression and advancing timing. Octane ratings are basically numbers for rating when a fuel will detonate. Adding timing and compression both make it easier for fuel to detonate, so you need more octane to prevent that. In a nutshell.

[05.Banshee.SE]

http://www.bansheehq.com/forums/index.php?showtopic=104421

 

http://www.bansheehq.com/forums/index.php?showtopic=96721

 

http://www.bansheehq.com/forums/index.php?...t=0&start=0

 

Check out these topics. I just installed my head, domes, and timing plate.

 

Pro Design Coolhead + 21cc domes, timing +4....definately gave me more punch and power across the entire RPM range. Well worth it.

[MJohnson3764]

http://www.bansheehq.com/forums/index.php?showtopic=104421

 

http://www.bansheehq.com/forums/index.php?showtopic=96721

 

http://www.bansheehq.com/forums/index.php?...t=0&start=0

 

Check out these topics. I just installed my head, domes, and timing plate.

 

Pro Design Coolhead + 21cc domes, timing +4....definately gave me more punch and power across the entire RPM range. Well worth it.

 

Hey Banshee. Do you use premium gas in your quad after those mods or did you have to step it up to higher octane? And what are the standard steps for octane levels? Is it 93 prem, then 104, then 110?

 

What do you guys think I would have to use in terms of octane level with those mods im talking about getting?

[dajogejr]

Every engine is different.

 

Cranking compression is not the tell tale factor in what octane gas you need, compression RATIO is...

However, it's a helluva lot easier to screw in a compression gauge then for the average guy to calculate the compression ratio. It involves several measurements.

 

That being said....

 

In my opinion, 21cc domes and +4 advance and you should be ok with 93 pump gas. Although bumping timing and compression don't usually require a jet change (that small of changes anyway) it's a good idea to make sure you start off a bit rich and jet down.