HEAD GAMES

[ou812]

Not sure the Indy heads will like the steeper seat...from what I've seen anyway.

[RevTheory]

Do you happen to know the top cut of your existing seats and how well it transitions into the chamber?

[CGT]

I think knowing how the engine is run would be useful info, drag car 6000 converter? Besides all that. I think the lift mentioned would be worth some power (more so than the change in duration listed)..., the compression mentioned also(I get that you don't want to change pistons), the valve job could be also if done correctly...depending on what you have now and what you go to. I probably wouldn't do anything drastic different with the valve size either.

Are you running a vacuum pump?...if not adding one could get you a good start towards your 30 hp without getting real crazy with anything.

[moparian]

ou812 there not a indy head just old set w7 s, Not sure on the top seat angle,knightengines the seats might be a job for you after xmas. Here is a pic of the head

[RevTheory]

I'd leave the cam & valve size.
Switch to 50 deg seats & rework the ports a little to suit.
50 deg seats will make the motor 'see' less seat to seat duration while bumping up available flow time/area.

What, if anything, would you do to the valve back cut to complement the new seat configuration?

[KnightEngines]

ou812 there not a indy head just old set w7 s, Not sure on the top seat angle,knightengines the seats might be a job for you after xmas. Here is a pic of the head

Those chambers look good for 50 deg seats, will work nice.
Are you in Australia? I can do it in January no probs, back in the shop after the 6th.

I'd change the valve back cut, likely to 38 deg, but a bit of experimenting with junk valves will tell the story.

[moparian]

ou812 there not a indy head just old set w7 s, Not sure on the top seat angle,knightengines the seats might be a job for you after xmas. Here is a pic of the head

Those chambers look good for 50 deg seats, will work nice.
Are you in Australia? I can do it in January no probs, back in the shop after the 6th.

I'd change the valve back cut, likely to 38 deg, but a bit of experimenting with junk valves will tell the story.

No problem,i am in vic,i will contact you in the new year mate

[Fatman]

I'd leave the cam & valve size.
Switch to 50 deg seats & rework the ports a little to suit.
50 deg seats will make the motor 'see' less seat to seat duration while bumping up available flow time/area.

Sounds good what would i pick up in cfm? should i try and lift more?If the seat see's less duration would cranking comp increase a little too .cheers

I don't think the engine sees less duration seat to seat. And i don't think it bumps up available flow time/area either.

[steve cowan]

I'd leave the cam & valve size.
Switch to 50 deg seats & rework the ports a little to suit.
50 deg seats will make the motor 'see' less seat to seat duration while bumping up available flow time/area.

Sounds good what would i pick up in cfm? should i try and lift more?If the seat see's less duration would cranking comp increase a little too .cheers

I don't think the engine sees less duration seat to seat. And i don't think it bumps up available flow time/area either.

any chance you could share you opinion on steeper seat angles and what they do ?

[KnightEngines]

I'd leave the cam & valve size.
Switch to 50 deg seats & rework the ports a little to suit.
50 deg seats will make the motor 'see' less seat to seat duration while bumping up available flow time/area.

Sounds good what would i pick up in cfm? should i try and lift more?If the seat see's less duration would cranking comp increase a little too .cheers

I don't think the engine sees less duration seat to seat. And i don't think it bumps up available flow time/area either.

If you reduce flow at low lift & reduce reverse flow at low lift your flow reduction in both directions at the start and end of the lift curve is reduced - effectively making the motor see less duration.
The improved high lift flow increases the available flow at higher piston demands, effectively increasing the available time/area (although not actually increasing time/area the effect is the same).

[Fatman]

Sounds good what would i pick up in cfm? should i try and lift more?If the seat see's less duration would cranking comp increase a little too .cheers

I don't think the engine sees less duration seat to seat. And i don't think it bumps up available flow time/area either.

any chance you could share you opinion on steeper seat angles and what they do ?

Seat to seat duration isn't going to change with a seat angle change. With a seat angle change, the duration seen at the same valve seat gap changes (as the valve initially starts to open). I'm referring to the distance between the seat on the valve and the seat on the head when I say valve seat gap. Not referring to valve lift. For example, the gap between a 50 deg seat at .040" valve lift is less than the gap between a 45 deg seat at the same .040" valve lift. Valve timing stays the same regardless of seat angle but the gap seen between the seat is different at the same timing points. At very low lift anyway. Not sure whats happening as the valve gets further away from the seat. So I think a steeper seat angle will have less area under the curve when plotting duration and seat gap. Just my opinion.