Low power on a 427
You know Martin, there is a TON of room for a set of 35Rs under a CTS V, and there is a 3bar map HPT can do 
72cc chambers seem awfully big. I dont think static compression is 11:1, almost seems it would be lower.
FWIW, AZ power and Sound is out of business last I heard. What color is this car? Buy it off ebay?
Louis ( on NABR too )
72cc chambers seem awfully big. I dont think static compression is 11:1, almost seems it would be lower.
FWIW, AZ power and Sound is out of business last I heard. What color is this car? Buy it off ebay?
Louis ( on NABR too
)The heads on my car have 72cc chambers and the compression is 11.7 :1.
( not the car in my sig,lol.) If it was small, it would make more Tq.... if it was big, it would make more power. Its just a pooch all around. most anything ,especially with an AFR, with a 4" arm should make 400 rwtq from the dig, it doesnt.
Maybe it was built for boost? Maybe if you pull a plug you can see into the cylinder with something (I know they make fibre optic cameras) to see if the pistons are dished.
-Geoff
-Geoff
Just did a compression test on a cylinder and came up with 190psi. I'll do the rest tomorrow along with a leakdown test. While I'm at it I'll pull the intake manifold and check out how the intake runners were ported.
Tony, how can I tell what type of AFR head it is without pulling it off, chamber cc, runners, I see a serial # on the front of the head, will that help?
Tony, how can I tell what type of AFR head it is without pulling it off, chamber cc, runners, I see a serial # on the front of the head, will that help?
I would encourage you to do the leakdown test ASAP....I feel you might have a bent valve so your down a cylinder and possibly blowing compression back up the intake manifold (disrupting the flow from all other cylinders) causing the flutter and the spitting you were describing in the lower RPM's. That would hurt power output significantly leaving you with numbers similar to what your producing.
Its just a theory of course but something is holding that engine back....
Your cranking pressure is good kind of ruling out a cam installed wrong so we can eliminate that as a possibility.
If your leakdown is good then its time to really start scratching your head and diagnosis from there gets a bit more difficult.
I have a hunch it wont be good....maybe someone over-revved the engine and slightly bent a few valves....you never know.
Tony
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Did a leakdown test and came out really good, 4-5% for each cylinder
Pulled the head and measured bore and stroke to verify it's a 427, bore 4.125" and stroke about 4" so that checks out.
I'm looking at the pistons right now and checking piston deck clearance and dish. I'll post some pics up of the pistons.
Pushrod info - 7955 comp cams - 7.400" .080
Head Serial# 00016670 then it's stamped #1660 in the head
Height from valve cover surface to head surface - 4.780"
Headgasket thickness .044"
Some pics of the disaster
Next step is pulling the cam and throwing it on my cam analyzer.
Pulled the head and measured bore and stroke to verify it's a 427, bore 4.125" and stroke about 4" so that checks out.
I'm looking at the pistons right now and checking piston deck clearance and dish. I'll post some pics up of the pistons.
Pushrod info - 7955 comp cams - 7.400" .080
Head Serial# 00016670 then it's stamped #1660 in the head
Height from valve cover surface to head surface - 4.780"
Headgasket thickness .044"
Some pics of the disaster
Next step is pulling the cam and throwing it on my cam analyzer.
Sound like you are getting there. I'd check the required pushrod length and what type of lifters it has in it. To much preload and you might hold the valves open, to little and lift might be sacrificed. I'd think you would hear to little though.
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Verdad Gallardo The 1660 is a small bore 225....(meant for 3.900 bore engines)
Measure across the chamber bore to confirm. It should be 3.900 (or very close to it)....not exactly ideal on a 4.125 bore engine.
Thats part of the problem but doubt that is all you will find....
I could port the heads you have to the correct spec if you have the time but you would have to lay the project up for awhile.
Anyway....keep digging....the skeltons are starting to fall out of the closet....LOL
Tony
PS...How did the FAST look?....was it stock or was someone in there as well? Send me pics of the port outlets if your not sure. A badly ported intake will make less power than a stocker.
PSS....I can tell looking at the pics its a small bore 225....at least Im 80% sure but the angle of the pic could be throwing me off. It also looks like the gasket ring is an eigth inch outside the chamber itself also confirming that but once again the pic is a bit blurry and at a bad angle to be completely sure.
Measure across the chamber bore to confirm. It should be 3.900 (or very close to it)....not exactly ideal on a 4.125 bore engine.
Thats part of the problem but doubt that is all you will find....
I could port the heads you have to the correct spec if you have the time but you would have to lay the project up for awhile.
Anyway....keep digging....the skeltons are starting to fall out of the closet....LOL
Tony
PS...How did the FAST look?....was it stock or was someone in there as well? Send me pics of the port outlets if your not sure. A badly ported intake will make less power than a stocker.
PSS....I can tell looking at the pics its a small bore 225....at least Im 80% sure but the angle of the pic could be throwing me off. It also looks like the gasket ring is an eigth inch outside the chamber itself also confirming that but once again the pic is a bit blurry and at a bad angle to be completely sure.
Last edited by Tony Mamo @ AFR; Feb 9, 2008 at 04:47 PM.
If its a 72cc chamber, thats less than 11:1 CR. A flat top with a 2cc relief and 70cc chambers is a tick over 11.2:1, thats a big dish, and its a bigger chamber.
Whats the cam say, got that out yet?
5% leakdown is a little high IMHO, I like to see 1-2 tops on a quality engine.
Whats the cam say, got that out yet?
5% leakdown is a little high IMHO, I like to see 1-2 tops on a quality engine.
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I just measured them and they are the smaller bore combustion chamber.
In interest of time I'll probably go with something designed for the bigger bore. LS7 heads?
Louis, the AFR PN 1660 is a 65cc chamber.
In interest of time I'll probably go with something designed for the bigger bore. LS7 heads?
Louis, the AFR PN 1660 is a 65cc chamber.
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From: Seattle area
Is your EVO a 2.3 stroker car or stock displacement?
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1050whp, It's silver with the WWII fighter plane scheme.
http://youtube.com/watch?v=EvfJG1qJdZY
we've gone 8.5's but the t-case ***** the bed on every hard launch so now we baby it off the line, sucks...
My car is 2.0L , the drag car is a 2.1L (longer rod bigger bore 4G63).
I really want to boost an LS so badly, but the CTS-V just isn't the right platform.
http://youtube.com/watch?v=EvfJG1qJdZY
we've gone 8.5's but the t-case ***** the bed on every hard launch so now we baby it off the line, sucks...
My car is 2.0L , the drag car is a 2.1L (longer rod bigger bore 4G63).
I really want to boost an LS so badly, but the CTS-V just isn't the right platform.
You could use the ls3/l92 6.2L heads, but you will have to use the factory intake till a Fast is released to fit the different style ports.
Yes you could go with some LS7's ported or not and a stock ls7 intake. I'd probably clean up the intake before install, but I bet it would make a lot of power with the right cam setup.
I'd keep the AFR's since you already have them (or sell them to get the ls7's sorry Tony
and Let Tony open the bore up to match the larger 427 block. Those 225's should get you well into the 500+ range even with a mild cam.
Yes you could go with some LS7's ported or not and a stock ls7 intake. I'd probably clean up the intake before install, but I bet it would make a lot of power with the right cam setup.
I'd keep the AFR's since you already have them (or sell them to get the ls7's sorry Tony
and Let Tony open the bore up to match the larger 427 block. Those 225's should get you well into the 500+ range even with a mild cam.
1050whp, It's silver with the WWII fighter plane scheme.
http://youtube.com/watch?v=EvfJG1qJdZY
we've gone 8.5's but the t-case ***** the bed on every hard launch so now we baby it off the line, sucks...
My car is 2.0L , the drag car is a 2.1L (longer rod bigger bore 4G63).
I really want to boost an LS so badly, but the CTS-V just isn't the right platform.
http://youtube.com/watch?v=EvfJG1qJdZY
we've gone 8.5's but the t-case ***** the bed on every hard launch so now we baby it off the line, sucks...
My car is 2.0L , the drag car is a 2.1L (longer rod bigger bore 4G63).
I really want to boost an LS so badly, but the CTS-V just isn't the right platform.
That would be great. I would love to see you guys see how far you can take a ls motor