Gun Drilling

[Anonymous]

I was reading an article about the new Mitsu Evo, and it mentioned that the cams and valves were hollowed out, or gun drilled. While this didn't decrease weight noticably, it decreased rotating mass. They said the thing revved up faster than a sportbike because of it.

I was wondering if it would be a wise investment to have the cams/valves on my new top end gun drilled???

[Guest]

gimme em i got a 12 guage to do gun drill em' u'll run 9's

[SappySE107]

You are a clever boy....go away.

The cams are half hollow already to retain some oil after the engine is shut down. Drilling out the center of the valves will weaken them, so thats up to you if you wanna try it. I would get the SIvalves over drilling the centers out, especially on a street driven car. Maybe drilling it out will help out but its a risk right now since it is untested in our engine. Thats up to you, but I would leave the cams alone for sure.

[Anonymous]

I forgot about the oiling system.

What are SI valves, valves out of a Civic SI???

I don't plan on doing the valves, I want this motor to last.

[SappySE107]

https://www.sivalves.com

[dykz34]

Si Valves appear to only be available in stock/OEM replacements. What would be the benefit of those over GM pieces? I noticed that the Si Valves were one-piece, how many are the GM pieces?

[SappySE107]

they are also lighter. Chris weighed the stock 3.1 valves compared to the SIvalves and they were considerably less. I have no idea what the diff is for us but I plan to find out when I have no debts and can afford to blow money.

[Anonymous]

I plan to find out when I have no debts and can afford to blow money.

Haha. When that happens gimme a call and I'll help you spend some cash.....

[dykz34]

Can you buy just ONE valve? I'd be curious how much the weight difference is... then, you only have to buy 23 more.

[SappySE107]

yeah, you can do that.

[dykz34]

What does one cost?

[SappySE107]

5.95 last I checked.

[dykz34]

Buy one then. Or, I can buy one... but I dont have precise weighing instruments OR a stock one to compare with.

[SappySE107]

Ill buy 24 when I can afford it. Shipping for 2 then 22 is more than shipping for 24 at once.

[GPXSS]

Stock 3.1 valve = 102.15grams
SI 3.1 replacement= 88.2g

so basically a 13 - 14% weight savings