Difference between a 3 and 5 angle valve grind?

[PanamaE30]

What exactly is the difference? Benefits? Drawbacks?

[Jon325i]

I've read a couple of articles about this. It seems that improved airflow is the benefit of the 5-angle approach and the drawback (of the 5-angle) is higher machining costs.

Don't know if there's more to it than that :|

Jon

[PanamaE30]

Hmm.. i've had trouble finding much information as well.

All google seems to pull up is ricer engine jobs :P lol

Anyone else got any information to contribute?

[mgold]

just a shot in the dark, but, 2 angles?











just kidding

[e30Matt]

Bascially, more angles = smoother radius = less disturbances in airflow meaning less turbulence for the mixture entering and exiting the cylinder, meaning better and more efficient combustion.

Stu, care to chime in?

[Jordan]

[Jand3rson]

Awesome diagram, Jordan. I've always wanted to know as well.

[Spaz]

good work man, i was just goning to write it all up :P

many people believe its the valve but its actually the seat....btw the m20 valve seats are replacable for those who didn't know.

[mcgrath]

I don't know if this will relate to car engines, but my dad use to be a tech for a suzuki 750cc race bike team and he said the 5 angle job is what they used but it was only good for about a race then they had to re-cut or replace the valves due to wear. Those bikes were turning well over 10k rpm though.

[PanamaE30]

Thanks for the diagram jordan, that about explained it all :)

Hmm interesting..

more research, must be done, yes.... :)

[fabianyee]

don't think it's good and worthwhile mod for daily car...
it doesn't give value for money...

unless it's a dedicated track/race car...

[bkelsey86]

actually it is worth while because it opens up the airflow of the engine making all those bolt ons and mods mreo effective since the head is a big bottleneck in the m20 at least.

[fabianyee]

you may be right...

my point was that it would not be worthwhile if the engine is close to bog standard. However, if the engine has been thru all the works then it'll yield better power....

For me, that would be the last stage of engine works.

[PanamaE30]

Well, my engine really needs some headwork.. and I was gonna get it ported and polished anyways, i figured i might as well save some time down the road and just do it now.