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Discussion Starter #1
Wanted to get yall's opinion on this before I make a change. I lost a rod this weekend at SGMP during the Pony Wars race. The current combination was World Block 4.125 bore 4.250 stroke CHI heads 50cc chamber 2.19int 1.71 exh and 15.3 comp 1080Dominator. Had damage to the #7 cylinder it will clean up at 4.185 from the looks of it and 2 rods and pistons. I was thinking of changing to a 4inch stroke good I beam rod and 4.185 bore or 4.200. This will mostly be run N/A but will see a 200hp shot of nitrous occassionally in a 3040lb Fox with a glide. My heads have been moved .100 to move the intake valve away from the cylinder wall. The question is do you think I will loose any ET from the current setup the best so far was [email protected].

My feeling is the 4inch stroke will be easier on parts and more durable than the 4.250 when we start running the nitrous. The motor should exccelerate faster also. What do you guys think?
 

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I'm putting a new shortblock together for next year as well.
9.5 Deck SBF as well.
4.170" bore and haven't made up my mind on the stroke yet either.

I'm stuck between something in the 3.9-4.1 range.

I haven't put much time into researching rod ratios or pistons yet.
But, I am interested in what some of the pro's have to say.

I see alot of guys going to a 4.100" Stroke and big bore on NOS combo's.
There's got to be something to it.

Good luck with your combination next year
 

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How much converter and where you shift?
 

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Discussion Starter #10
How much converter and where you shift?
5600 stall and I was turning the old motor 7800 out the back shifting at 7000. I will change what I need to change to make the motor happy.
 

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I'd go with a 4" stroke and bump the converter up where you need it.... we are talking 454 down to 440 or 3.2%... you will probably pick up by just the gain in shift point and the upper end of the RPM range heading to the stripe. The 454 is a lot of cubes on a SB head in the 5600-7800rpm range. Are the heads just the BIG out of the box CHI deal?
 

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Discussion Starter #12
No they were done by MPG heads and came off of one of there engine masters motors they are the old 218cc casting. They are small for the cubes I have been running around 238cc.
 

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Less cubes is better for that RPM range then....
 

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4 inch stroke is what I like. Too much side loading with the longer strokes on a small block IMO. I prefer the acceleration rate of the shorter stroke and RPM gained if the induction can handle it.
 

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Discussion Starter #15
I think the 4inch stroke is going to be the ticket with the heads I have. Maybe I will move up to the 55mm cam also. I kicked around going to aluminum rods but I make alot of passes every year (close to 200) and not sure I want to replace rods everytime I do a refresh any thoughts on the rods?
 
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