Cylinder Heads
Thread Starter
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Cylinder Heads
I have been researching heads (and threads associated) on the forum for awhile. I have come to the conclusion that with an older C4 (85 L98) that going above 180 CC intake without major cam or engine mods kills the L98 torque. Based on that assumption I am looking at the AFR 180 heads since they are fully ported out of the box. I am not looking at a magical HP number or torque number. The basic plan would be AFR 180 heads, SR base manifold and going with a front "Y" pipe from exhaust manifold to cat that is 2-1/2". I already am running 1.6 and 1.5 RR (which I would switch to the new heads), Plenum is ported and a 52 mm throttle body. Any suggestions?
BTW - a good head comparison chart that I found is located at:
www.users.erols.com/srweiss/tablehdc.htm
BTW - a good head comparison chart that I found is located at:
www.users.erols.com/srweiss/tablehdc.htm
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Personally I would avoid AFR heads, they are known to have many quality control issues. I've seen some of them first hand, I wouldn't buy them.
I'm also not a huge believer in the split rocker ratio. If you increase the amount of air coming into the engine it only serves to reason that you would need to increase the exhaust going out. If you need to tweak the lift or duration of the intake relative to the exhaust you can do so when selecting the camshaft and then you only have to run one size rocker.
I'm also not a huge believer in the split rocker ratio. If you increase the amount of air coming into the engine it only serves to reason that you would need to increase the exhaust going out. If you need to tweak the lift or duration of the intake relative to the exhaust you can do so when selecting the camshaft and then you only have to run one size rocker.
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by John A. Marker
I have been researching heads (and threads associated) on the forum for awhile. I have come to the conclusion that with an older C4 (85 L98) that going above 180 CC intake without major cam or engine mods kills the L98 torque. Based on that assumption I am looking at the AFR 180 heads since they are fully ported out of the box. I am not looking at a magical HP number or torque number. The basic plan would be AFR 180 heads, SR base manifold and going with a front "Y" pipe from exhaust manifold to cat that is 2-1/2". I already am running 1.6 and 1.5 RR (which I would switch to the new heads), Plenum is ported and a 52 mm throttle body. Any suggestions?
BTW - a good head comparison chart that I found is located at:
www.users.erols.com/srweiss/tablehdc.htm
BTW - a good head comparison chart that I found is located at:
www.users.erols.com/srweiss/tablehdc.htm
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Depends what you want to spend. Ported 113's would work well: for about a grand you should be able to get a real valve job and hopefully flow 240-250. AFR 180's work incredibly well in my opinion. Probably set you back a few more bills; you get the idea. Everyone will have their favorite as you will find out. That's what the board is for! There are other brands out there but I can't comment on them due to the fact I haven't tried them. Good Luck 
Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
You probably already know it but in case someone doesn't,
AFR has unported, 70% ported or fully ported versions.
Have them machine provisions for the temp sensors. Sometimes they forget.
Of course a 4th option is porting by hand by a really good and experienced person.
Are ya keeping the EGR?
There is a internal to external EGR passage change that occurs in 86-87 and you would have to draw the gas from #8 header primary(would mean obtaining 87 up exh manifolds or hooker 2149's)
D113's and AFR's don't have internal EGR because they are aluminum.
AFR has unported, 70% ported or fully ported versions.
Have them machine provisions for the temp sensors. Sometimes they forget.
Of course a 4th option is porting by hand by a really good and experienced person.
Are ya keeping the EGR?
There is a internal to external EGR passage change that occurs in 86-87 and you would have to draw the gas from #8 header primary(would mean obtaining 87 up exh manifolds or hooker 2149's)
D113's and AFR's don't have internal EGR because they are aluminum.
Last edited by pablocruise; Jan 6, 2005 at 03:44 AM.
Race Director
Joined: May 2003
Posts: 10,749
Likes: 41
Originally Posted by John A. Marker
I have been researching heads (and threads associated) on the forum for awhile. I have come to the conclusion that with an older C4 (85 L98) that going above 180 CC intake without major cam or engine mods kills the L98 torque. Based on that assumption I am looking at the AFR 180 heads since they are fully ported out of the box. I am not looking at a magical HP number or torque number. The basic plan would be AFR 180 heads, SR base manifold and going with a front "Y" pipe from exhaust manifold to cat that is 2-1/2". I already am running 1.6 and 1.5 RR (which I would switch to the new heads), Plenum is ported and a 52 mm throttle body. Any suggestions?
BTW - a good head comparison chart that I found is located at:
www.users.erols.com/srweiss/tablehdc.htm
BTW - a good head comparison chart that I found is located at:
www.users.erols.com/srweiss/tablehdc.htm
What about the TFS head. Good head for the price.......Flows 254CFM/195CC/62CC.
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Le Mans Master
Joined: Apr 2000
Posts: 6,341
Likes: 1
From: Shelton CT
I have an '85 vette with stock internals (cam/shortbock/etc..)
I am knocking on 11's doors with the car with a Superram/LPE 1 5/8" headers, dart iron eagles (ported) (200cc runners), 1.52rrs, Dana44 w/3.45 gears, and bolt ons.. (And114K mileson the engine)..
Did notice abit of low-end torque loss after the header/heads swap, but it came back once I tuned the car with my chips, or the ecm relearned stuff. Either way it IS running great..
Next stepis o upgrade to a roller cam/block when I chose to replace the shortbock in the future.. That should be good for another 30-40HP and higher rpm otential (game's over around 53-5400rpms with the stock cam/lifters)
I am knocking on 11's doors with the car with a Superram/LPE 1 5/8" headers, dart iron eagles (ported) (200cc runners), 1.52rrs, Dana44 w/3.45 gears, and bolt ons.. (And114K mileson the engine)..
Did notice abit of low-end torque loss after the header/heads swap, but it came back once I tuned the car with my chips, or the ecm relearned stuff. Either way it IS running great..
Next stepis o upgrade to a roller cam/block when I chose to replace the shortbock in the future.. That should be good for another 30-40HP and higher rpm otential (game's over around 53-5400rpms with the stock cam/lifters)
Last edited by MrNuke; Jan 6, 2005 at 08:12 AM.
Instructor
Joined: Dec 2004
Posts: 142
Likes: 0
I am running TFS 190's on my 355 with the TPI. I absolutely love them (other than the fact that I have to redo the head gasket lol). I noticed a great power increase over my stock heads.
Dont be totally taken by AFR's numbers. They come ported from their factory. A set of TFS heads with the same port job will outflow AFR's. Just dont go too big with the runner sizes. You'll kill your velocity thus hurting your bottom end. 190's is as big as I'd go on a TPI on a 350. Larger displacement engines (383's, 400+'s) like a bit more runner size depending on their cam and intake setup (superram, mini ram, stealth, etc).
Dont be totally taken by AFR's numbers. They come ported from their factory. A set of TFS heads with the same port job will outflow AFR's. Just dont go too big with the runner sizes. You'll kill your velocity thus hurting your bottom end. 190's is as big as I'd go on a TPI on a 350. Larger displacement engines (383's, 400+'s) like a bit more runner size depending on their cam and intake setup (superram, mini ram, stealth, etc).
Instructor
Joined: Jul 2004
Posts: 137
Likes: 0
From: CT
Originally Posted by comp
still not ,,anybody else open it ????
One of the funny links that's happier without the www.
Instructor
Joined: Jul 2004
Posts: 137
Likes: 0
From: CT
Originally Posted by MrNuke
I have an '85 vette with...
dart iron eagles (ported) (200cc runners)...
dart iron eagles (ported) (200cc runners)...