[John Langer]

Originally Posted by Stan Weiss

Aaron,
Using a 572 ci engine, Bore = 4.375" Stroke = 4.75" Rod = 6.75 and CR = 15:1. If we say that peak cylinder press is @ 12.5 ATDC and is 1650 psi. This decay graph is based solely on PV changes no heat added or removed. The green line is done using a K- Exponent of 1. Most of the Paper I have seen say it is around 1.38 so the red line is done using K-Exponent of 1.4. I do not know where John's exhaust valve is set open, but a 320 degree exhaust in @ 110 ecl evo 90 ATDC, @ 118 ecl evo 98 ATDC. The Rod and Crank are 90 Degrees to each other @ 70.62 ATDC.

Stan

Parameters are close enough for arguments sake on the bore/stroke/rod and compression but the cam events aren't close. You have to take into consideration the amount of air the piston can cycle in and out of the cylinder with respect to the cam timing events to fully understand what is going on in the hole.

[johnta1]

Stan, what would it look like with the EVO of 84/86º ATDC spec?

[Half-Inch Stud]

So all this boils down to a Rocker strategy to me. Steel on xhaust, aluminum on Intakes.

And good constraints in the design to keep the rockers on their bubble; the valve stem.

[Stan Weiss]

Originally Posted by John Langer

Parameters are close enough for arguments sake on the bore/stroke/rod and compression but the cam events aren't close. You have to take into consideration the amount of air the piston can cycle in and out of the cylinder with respect to the cam timing events to fully understand what is going on in the hole.

John,
That is true. This was just a guess of peak cylinder pressure and where after TDC it happened. The exhaust points were just to get a reference for where one could look on the graph to see cylinder pressure at what might be evo. This graph is solely based on PV change and does not have the exhaust valve ever opening.

Stan

[Stan Weiss]

Originally Posted by johnta1

Stan, what would it look like with the EVO of 84/86º ATDC spec?

John,
The exhaust valve never opened during the cycle that was graphed.

Stan

[johnta1]

Thanks.

You used the 90º spec, figured it was the EVO.

[Aaron Quinton]

We're missing the point why the cam gear/belt failed but you are right. The intake is way short and the exhaust is way long on this type of engine.

But other than ego stroking, why not say what it is? If not just be quiet and rock on? I've never gotten the talk in code deal to keep da's interested. Why not just share what you're willing to share or STFU and say nothing? I don't get it other than stroking an ego.

I respect anyone that has accomplished what you done. Killer to the end. Just either say what you're willing to share or STFU. The ego building on someone else's brain bothers me. We all know you ECM fk's run the same mid west engine guy. Why be such a d(*& when I can buy the power from the same place?

And you can't tell me it's not knocking skirts off the pistons in that set up so WTF? There's no way your engine builder would have went that far. We both know it is unless you're running a tall deck block so wtf?

Originally Posted by John Langer

Parameters are close enough for arguments sake on the bore/stroke/rod and compression but the cam events aren't close. You have to take into consideration the amount of air the piston can cycle in and out of the cylinder with respect to the cam timing events to fully understand what is going on in the hole.

[John Langer]

Originally Posted by Aaron Quinton

We're missing the point why the cam gear/belt failed but you are right. The intake is way short and the exhaust is way long on this type of engine.

But other than ego stroking, why not say what it is? If not just be quiet and rock on? I've never gotten the talk in code deal to keep da's interested. Why not just share what you're willing to share or STFU and say nothing? I don't get it other than stroking an ego.

I respect anyone that has accomplished what you done. Killer to the end. Just either say what you're willing to share or STFU. The ego building on someone else's brain bothers me. And all you ECM fk's run the same mid west engine guy. Why be such a d(*& when I can buy the power from the same place?

And you can't tell me it's not knocking skirts off the pistons in that set up so WTF? There's no way Tony would have went that far. We both know it is unless you're running a tall deck block so wtf?

I have no idea what you are talking about. I will not give out my cam design. I do not have a piston skirt issue. Never have. Have run the same pistons for over 150 passes with this stroke. I do not have a tall deck. 10.100 deck. I don't need me ego stoked @$$ kissed or anything like that at all. Don't know whose brain your referring to, I'm just a dumb construction guy? I know why the belt jumped. I have posted in this post why the belt jumped. Build a max effort na piece and you can use every six sigma tool there is to build a better box. Until then I guess stfu?

[Aaron Quinton]

No one asked you to give out any cam info. Wow

Man if you're not having skirt issues with that pull out you da man. Six Sigma to the front (green belt, black belt, sponsor)! lol Process TTFMF! What does Tony say?

Originally Posted by John Langer

I have no idea what you are talking about. I will not give out my cam design. I do not have a piston skirt issue. Never have. Have run the same pistons for over 150 passes with this stroke. I do not have a tall deck. 10.100 deck. I don't need me ego stoked @$$ kissed or anything like that at all. Don't know whose brain your referring to, I'm just a dumb construction guy? I know why the belt jumped. I have posted in this post why the belt jumped. Build a max effort na piece and you can use every six sigma tool there is to build a better box. Until then I guess stfu?

[mgarblik]

Originally Posted by Half-Inch Stud

So all this boils down to a Rocker strategy to me. Steel on xhaust, aluminum on Intakes.

And good constraints in the design to keep the rockers on their bubble; the valve stem.

I agree to a point. At the higher end of spectrum, I see little reason to use aluminum rocker arms at all. Developments in steel rocker design, contour machining of the rocker profile, produce a much stronger steel rocker arm at near the weight of aluminum. With seat pressures of 400 lb. +, open pressures of over 1000 lbs. and high RPM, steel throughout is the way to go. Eliminates allot of potential headaches.

[Dragncar]

Even with my low end junk steel is the way to go. I run Norris SS rockers. The old advertisement said the reciprocating weight was less than aluminum. I thought that was what mattered, stiffer too.
My lash just never changes. Best 260$ I ever spent.
Tom S says he knows the Norris folks and they would do a Pontiac run if they had a certain amount ordered.
I wonder how many and for how much $ ?

[BruceWilkie]

Last I looked Crower had stainless rockers in both stud and shaft for our Pontiacs. Custom too if you want !

[Aaron Quinton]

Fixed it for you in caps.

Originally Posted by John Langer

I have no idea what you are talking about. I will not give out TONY's cam design. I do not have a piston skirt issue YET. Never have. Have run the same pistons for over 150 passes with this stroke. I do not have a tall deck. 10.100 deck. I don't need me ego stoked @$$ kissed or anything like that at al. Don't know whose brain your referring to (TONY'S), I'm just a dumb construction guy ARE YOU? I know why the belt jumped YOU SURE? I have posted in this post why the belt jumped. Build a max effort na piece and you can use every six sigma tool there is to build a better box 6S ONLY ALLOWS THE DFKS TO SEE YOUR TAIL. Until then I guess stfu? MAYBE