test trial heads...
Thread Starter
Teching In
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test trial heads... Installing a set of P&P heads that flow 303, but theres a catch, the intake valves are 2.08 and 1.60 exhaust. Like I said these are just a trial run, but need to find a good cam, big enough duration to give me the air i need, but not too much lift, cause I know I'm going to have clearance problems.
Here's what I got. 00 Z28 M6 41k stock internals,ls6 intake,mac headers,true dual x-pipe,whisper lid,160 stat,tb bypass,bellow,ngk.
RWHP 360.0
RWTQ 360.4
I need some help finding a cam for this application. If the heads don't work no harm done, but if they do, can't wait to see the results. Thanks for the help.
Here's what I got. 00 Z28 M6 41k stock internals,ls6 intake,mac headers,true dual x-pipe,whisper lid,160 stat,tb bypass,bellow,ngk.
RWHP 360.0
RWTQ 360.4
I need some help finding a cam for this application. If the heads don't work no harm done, but if they do, can't wait to see the results. Thanks for the help.
Launching!
Joined: Mar 2003
Posts: 250
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From: Oceanside CA
Hmm, that's a tough one. The intakes are just flat too large for the CI's you're running, unless you pressurize it. Without enlarging the chamber as you would in a larger bore motor, the intake valve is going to be seriously shrouded.
A GM hot cam might be an interesting place to start. For something a bit larger, but still safe on the lift, a Comp XR281 should work...
A GM hot cam might be an interesting place to start. For something a bit larger, but still safe on the lift, a Comp XR281 should work...
Thread Starter
Teching In
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Originally Posted by Phil99vette
If the cylinder head yeilds good flow #s on a 3.90 bore why would the valves be too big?
Phillip
Phillip
info please......
I'd like to see an answer to Phil's question. I think if the heads perform well on a 3.90 bore, that they would be OK on the car. Drew, I personally don't think cam selection will effect how the heads perform. Either the heads themselves are going to work on a 3.90 bore, or there not. Sure a cam might change the HP results a little, but it is only going to work as much as your heads let it. A 2.08 valve takes up alot of area in the combustion chamber. If it opens and the air is immediatlly slammed into the cylinder wall instead of being allowed to dispurse effectivlly like it would with a smaller valve, then I can't see much being gained from moving camshaft numbers around. A 231/237 would be a good choice, but I don't think you will be able to fit it without P/V clearence. You deffinatlly need to stick with a cam that you know works. This way you will know if the problem is in the heads or not.
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I would first check the bore on the head since it is common for a 2.08 to be in a head made for a bigger bore.ie The gasket could leak if it's not right.
Now for a Cam I would go with a smaller intake duration to help P/V clearence unless you are notching the pistons.
Maybe some thing like 226/234 XE lobe .575/.590 lift on 112.
Now for a Cam I would go with a smaller intake duration to help P/V clearence unless you are notching the pistons.
Maybe some thing like 226/234 XE lobe .575/.590 lift on 112.
how much are the heads cut? The 231.237 might fit, I will discuss it with Joseph.
Jason
Jason
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Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Thread Starter
Teching In
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Heads flowed at boyd's in the okc area, heads have not been milled, not sure on 3.90 flow(I'll find out), it is a stock stroke.
Slowhawk that sounds like something that will work. A 5.7 lift intake was kinda what i was thinking, but if i can go bigger 231/237, and still have the clearance, its on....
Slowhawk that sounds like something that will work. A 5.7 lift intake was kinda what i was thinking, but if i can go bigger 231/237, and still have the clearance, its on....
Launching!
Joined: Mar 2003
Posts: 250
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From: Oceanside CA
Originally Posted by Beast96Z
I'd like to see an answer to Phil's question...
Didn't mean to imply it wouldn't work, it just isn't an optimum use of the design given the engine size.
TECH Resident
Joined: Sep 2003
Posts: 848
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From: Working in the shop 24/7
Originally Posted by Beast96Z
A 2.08 valve takes up a lot of area in the combustion chamber. If it opens and the air is immediately slammed into the cylinder wall instead of being allowed to dispurse effectively like it would with a smaller valve, then I can't see much being gained from moving camshaft numbers around.
Right on the money!
Bigger ain't necessarily better!
Ed
Thread Starter
Teching In
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I guess what I'm asking is this. What is the max lift I could go with, without having p/v clearance issues. The reason I'm so concerned with the cam, is if these heads aren't producing well, they are coming off, and the stocks are back on, and I'm stuck with the cam.(quote: test trial heads)
If you had these heads, what cam would you go with? dur.lift.lsa
If you had these heads, what cam would you go with? dur.lift.lsa
Launching!
Joined: Mar 2003
Posts: 250
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From: Oceanside CA
Originally Posted by drew-00-ls1
I guess what I'm asking is this. What is the max lift I could go with, without having p/v clearance issues. The reason I'm so concerned with the cam, is if these heads aren't producing well, they are coming off, and the stocks are back on, and I'm stuck with the cam.(quote: test trial heads)
If you had these heads, what cam would you go with? dur.lift.lsa
If you had these heads, what cam would you go with? dur.lift.lsa
Originally Posted by Scott Turvey
I can tell you that a .600 lift with the stock valves clear, so .590 should be fine as the valve "looks" only marginally large from the piston's perspective.