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Discussion Starter · #1 ·
Can someone tell the difference between the 4 mil +5 rod and the 4 mil stock rod. Logic tells me moving the rod 4mm is 4mm no matter how long the rod is. A longer rod will raise the piston but still have the same stroke. Then you put stroker or blaster pistons in it to lower the top of the piston down. I'm confused!
 

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Can someone tell the difference between the 4 mil +5 rod and the 4 mil stock rod. Logic tells me moving the rod 4mm is 4mm no matter how long the rod is. A longer rod will raise the piston but still have the same stroke. Then you put stroker or blaster pistons in it to lower the top of the piston down. I'm confused!


well to my understanding it increases life by correcting the geometry with the long rod shorter piston
 

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well to my understanding it increases life by correcting the geometry with the long rod shorter piston




Really Quick:



Long Rod = less stress on the piston

Short Rod = More Stress on the piston



Longer Rod = Piston will come closer to the top of the Bore and Accelerate away slower than a Short Rod. (longer rod will have more dwell)



The Smaller the centerline angle the less the side loading on the cylinder.



Basically, The longer rod will have less centerline angle for the same crank angle than the shorter rod and therefore has lower side loadings



mechanical stress is less with the longer rod length
 

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they're pros and cons with both, i perfer the short rod, you can just use ur banshee pistons no need to bore to 66mm(blaster piston std. size), now the rod angle imo does not really come in to play, ive dynod both plenty of times with no power gain bwtn the 2 as long as the set-ups are similar, its really a toss up if your at a stk banshee bore now and wanted to go with the long rod youd need 2 new pistons(573 or 795), 2 9 degree domes, and of course the crank. you go with the standard length rod u really just need the crank and the spacer it comes with , recommended that you get an aftermarket head but its up to you on what kinda of compression and squish you want, the plus is that if your pistons were in good condition you could still run them. theres more to it then what ive said but imma try to keep it pretty general.
 

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thank you dave, obviously with a 4 mm crank long or standard rod its moving the piston up 2mm and down 2mm we use a gasket-spacer-gasket... 2-.020 and 1-.060 spacer roughly like 2mm when torqued down, its a little on the safe side of things with the squish but it'll work, on personal motor or on a motor id set-up i might use a .012 and .020 gasket to tighten the squish some. i also cut domes for some apps. but the combo of spacer(s) and gaskets works real well.
 

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i also forgot to mention that our crank is made to more of a drop in and go with the gaskets and spacer. but if your setting the motor up for drags and somthing along those lines...port heights, durations, squish etc. etc. could/should be tweaked for maxium performance.
 

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Discussion Starter · #11 ·
Thanks Bill for all the info, I'm not looking to build a 4 mil. I had bought a bottom end for the cases for my 7 and that was a bonus inside. It is a fully rebuildable 4 mil short rod. I think i will put it on the shelf until i rebuild the 350.
 
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