Valves and compression
Thread Starter
Racer
Joined: Aug 2011
Posts: 343
Likes: 10
Valves and compression
I was surfing throughout the internet earlier this week and I was reading an article were I guy was porting his heads. He was opening up the combustion chambers around the intake valve. He stated that it would help them flow a little better, but you will lose a little compression. He also stated that putting in a larger valve would help boost the compression a little. He didn't mean a larger diameter valve, but a stock size valve just a little thicker on the face of the valve to create compression. Anyone ever heard of this? Or tried this?
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
Maybe getting the valve higher up on the seat.
Okie guy from Youtube?
Some good stuff and a lot of hackery on the web imo head mods are dependent on application. Without being expert or having access to a bench really hard to tell if youre going in a + or - direction.
Okie guy from Youtube?
Some good stuff and a lot of hackery on the web imo head mods are dependent on application. Without being expert or having access to a bench really hard to tell if youre going in a + or - direction.
Thread Starter
Racer
Joined: Aug 2011
Posts: 343
Likes: 10
Maybe getting the valve higher up on the seat.
Okie guy from Youtube?
Some good stuff and a lot of hackery on the web imo head mods are dependent on application. Without being expert or having access to a bench really hard to tell if youre going in a + or - direction.
Okie guy from Youtube?
Some good stuff and a lot of hackery on the web imo head mods are dependent on application. Without being expert or having access to a bench really hard to tell if youre going in a + or - direction.
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 112
From: Michigan
A thicker valve head would reduce cc of the chamber, but now your valve is heavier. Polishing the chamber and deshrouding the valve will increase cc of the chamber. You can offset either by milling the head some, using a thinner gasket or a dome piston.
Race Director
Joined: Apr 2003
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From: moraga ca
I was surfing throughout the internet earlier this week and I was reading an article were I guy was porting his heads. He was opening up the combustion chambers around the intake valve. He stated that it would help them flow a little better, but you will lose a little compression. He also stated that putting in a larger valve would help boost the compression a little. He didn't mean a larger diameter valve, but a stock size valve just a little thicker on the face of the valve to create compression. Anyone ever heard of this? Or tried this?
Last edited by 383vett; Feb 13, 2014 at 01:39 PM.
Thread Starter
Racer
Joined: Aug 2011
Posts: 343
Likes: 10
Essentially what the guy is saying is true. Anytime material is removed from the compression chamber, the compression is decreased, although the gains from the cleanup will outweigh the near negligible decrease in compression. Using a thcker valve will increase compression, but as noted above, the valve will be heavier and the amount of compression gain would be negligible. An increase in compression of 1 point is worth approximately 3-4%. On a 300hp motor, that is about 10-12hp. The amounts you are talking about probably won't change compression more than a tenth or so.
Race Director
Joined: Apr 2003
Posts: 17,697
Likes: 1,666
From: moraga ca
