HEAD GAMES

[moparian]

I was thinking of doing some upgrades on my heads,ATM the combo makes 750 hp at 7700 rpm with 750 net lift with 355 cfm on a 45 degree seat 2.100 valve and 365@900 lift,bore size is 4.100 x 4 inch stroke 422 ci 12.6 comp 190 cranking comp 278/284@050 on a 109 l/c now there are 3 things i was thinking of changing to pick up a extra 30 hp may be,what do you guys think?
1 May be go to a 52 degree seat
2 a bit less @050 say 270/278 on a 111 l/c and 850 net lift would increase cylinder pressure and access to more air
3 a 2.200 valve with the new seat angle
interesting to see the feed back. Cheers

[econo racer]

I vote for a little smaller cam on 109 -110 lobe. maybe 5-8 degrees less.

[mag2555]

I would first want to know what vacuum the motor is pulling now at peak rev's, as if it currently close to 1" Hg then reworking the heads to pass more air will not make you more HP.

[CGT]

I would first want to know what vacuum the motor is pulling now at peak rev's, as if it currently close to 1" Hg then reworking the heads to pass more air will not make you more HP.

Which would suggest that gross airflow is the only path to making more power...definitely not the case. Anyway...can you tell us more about the heads, 2.8ish CSA?, timing requirements, how much peak torque does it make and where?

[RevTheory]

I think a net valve lift of .357/D with the overlap area a 278/284, 109 cam provides is a prime candidate for a steeper seat configuration. I *think* I'd try that, assuming you have someone in mind who can do it well (more than just three new cuts on the seats), before pulling duration out or widening the lobe centers.

[mag2555]

No, I am just saying that it will always pay to know where the cork is before potentially wasting time and money on a mod/ change.

[moparian]

Minimal CCA is 2.88 i think that is just behind the seat area,i am not sure on vacuum at peak power total timing 33. Here is the old dyno sheet

[moparian]

I think a net valve lift of .357/D with the overlap area a 278/284, 109 cam provides is a prime candidate for a steeper seat configuration. I *think* I'd try that, assuming you have someone in mind who can do it well (more than just three new cuts on the seats), before pulling duration out or widening the lobe centers.

I know what your saying not many people i trust to do it lol,what do you think it would pick up in cfm and hp power?

[ou812]

I was thinking of doing some upgrades on my heads,ATM the combo makes 750 hp at 7700 rpm with 750 net lift with 355 cfm on a 45 degree seat 2.100 valve and 365@900 lift,bore size is 4.100 x 4 inch stroke 422 ci 12.6 comp 190 cranking comp 278/284@050 on a 109 l/c now there are 3 things i was thinking of changing to pick up a extra 30 hp may be,what do you guys think?
1 May be go to a 52 degree seat
2 a bit less @050 say 270/278 on a 111 l/c and 850 net lift would increase cylinder pressure and access to more air
3 a 2.200 valve with the new seat angle
interesting to see the feed back. Cheers

Up compression to as close to 15:1 as possible, 2.125 Ti intake valve, rework the ports and bowl/VJ some for larger intake valve, possibly re work the intake manifold...keep the 45 seat angle. Should pick up 30HP.

[moparian]

I was thinking of doing some upgrades on my heads,ATM the combo makes 750 hp at 7700 rpm with 750 net lift with 355 cfm on a 45 degree seat 2.100 valve and 365@900 lift,bore size is 4.100 x 4 inch stroke 422 ci 12.6 comp 190 cranking comp 278/284@050 on a 109 l/c now there are 3 things i was thinking of changing to pick up a extra 30 hp may be,what do you guys think?
1 May be go to a 52 degree seat
2 a bit less @050 say 270/278 on a 111 l/c and 850 net lift would increase cylinder pressure and access to more air
3 a 2.200 valve with the new seat angle
interesting to see the feed back. Cheers

Up compression to as close to 15:1 as possible, 2.125 Ti intake valve, rework the ports and bowl/VJ some for larger intake valve, possibly re work the intake manifold...keep the 45 seat angle. Should pick up 30HP.

What do you think the ti valve at 2.125 over the ti 2.100 valve that is in it is worth? i would have to get new slugs to up the comp in it,i am not sure i am willing to do that at this stage.

[RevTheory]

How much valve area do you need at TDC and how much valve can you stuff in a 4.100 bore? I'd try to make my existing valve as efficient as possible at mid/high lifts at the expense of low lift. I could definitely be wrong here.

I bet you're pushing .300 lift with the piston parked at TDC. I'd be curious to know just for shits and giggles.

[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.

[moparian]

How much valve area do you need at TDC and how much valve can you stuff in a 4.100 bore? I'd try to make my existing valve as efficient as possible at mid/high lifts at the expense of low lift. I could definitely be wrong here.

I bet you're pushing .300 lift with the piston parked at TDC. I'd be curious to know just for shits and giggles.

162 cam lift at TDC x 1.75 rocker= 283 at the valve on a 109 c/l but i am at 103 c/l so lift at TDC at the valve from memory 308 may be a bit more i have to check but lash would bring it down a little too

[moparian]

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

[KnightEngines]

Should pick up from .500 up about the same at .400 & loose a little below that.
Up to 10cfm or so at .700" & up, maybe a tad more.