[grandam1979]

The Dyno or track will tell the story until then it’s all speculation all combinations are different and respond differently. I personally have had a few engines built close to the op engine so I know what I thinks going to happen. And it’s still safe to 6000 or less

[pastry_chef]

Originally Posted by Steve C.

"Mean and maximum piston speeds are still valuable calculations for any engine builder making a change to a proven formula. Exceeding 5,000 fpm in mean piston speed should get your attention and prompt rethinking on parts selection.

Old 2007 thread on Speed-talk I made a PDF file from. Pleased to see we can still browse it.
https://www.speed-talk.com/forum/viewtopic.php?t=6211

Sun Apr 22, 2007 comment from Darin Morgan.

It seems to me that the engines must operate between 4500 to 5500fpm mean piston speed to produce the highest overall average VE curve.. I came to this conclusion through a decade of experimental testing and plotting the variables mathematically.

[tom s]

I have had enough street engines on the dyno with stock type dual plane intakes that I know our engines give up in the 5200 range to say that is a safe RPM until you get on the dyno.JMHO,Tom

[Joe's Garage]

Originally Posted by tom s

I have had enough street engines on the dyno with stock type dual plane intakes that I know our engines give up in the 5200 range to say that is a safe RPM until you get on the dyno.JMHO,Tom

^^^^^THIS^^^^^

Just set it at 5200 until you get to a dyno.

Undoubtedly your bottom end will handle more RPMs, but you will be more consistent and it will pull harder thru the gears 'short-shifting'.

Enjoy it!

[Dragncar]

Originally Posted by grandam1979

Nothing you just said has anything to do with his combination Again his combination is safe to 6000 or less.

Yes it does. If I can not get enough air into a far better flowing head with a much larger cam shifting at 5500RPM he does not have a snowballs chance in you know what getting his engine to truly pull to 6K.
5200 it is.

[Dragncar]

Originally Posted by Stan Weiss

I find it hard to believe someone as smart as Dan would say something as foolish as that.

Stan

That is exactly what he told me, we we friends and talked a lot over 20+ years.
Pontiac ports are puny. 455s have a ton of piston speed.
There is nothing you can do with a iron D port head. Port it, helps a little. They can only take so much cam before they go into tumble.
Hands are tied, not much you can do besides tune for mid range torque.
Its not like a BBC where we can get 455ci with a 4" stroke crank, they can. They also have much better head design. Simply out flow us.
Its why they rev and we are stuck being a tq monster.
Put a big time aluminum head on the Pontiac and it changes it all but that is not what were are talking about.

[grandam1979]

Originally Posted by Dragncar

Yes it does. If I can not get enough air into a far better flowing head with a much larger cam shifting at 5500RPM he does not have a snowballs chance in you know what getting his engine to truly pull to 6K.
5200 it is.

Ok for the last time I personally have never ever had a 455 combo go faster shifting at 5200 over 5500-6000 from stock to a .700 lift roller. Again his personal track or dyno time will give the answer not you not being able to have someone not agree with you. Also the op got his answer 20+ post ago get over it.

[Qball]

Originally Posted by grandam1979

Ok for the last time I personally have never ever had a 455 combo go faster shifting at 5200 over 5500-6000 from stock to a .700 lift roller. Again his personal track or dyno time will give the answer not you not being able to have someone not agree with you. Also the op got his answer 20+ post ago get over it.

I did get my answer and a whole lot more great information!

Thanks to all who took the time to reply. I sure do appreciate it.

Mods, you can lock this up.


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[grandam1979]

Qball, sorry about having your post go off topic like that.

[Qball]

Originally Posted by grandam1979

Qball, sorry about having your post go off topic like that.

Eh, it happens. No worries.


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