Quote:
Originally Posted by SStockDart
This entire conversation affects our car. However, it seems that everyone is making a bigger deal out of it than it really is. Their is no difference in using the low deck block than using a decked tall block except the main bearings and distributor. Unless NHRA starts measuring crank CL to the deck (for everyone!!!) Expect to see decked 440 blocks. So, the end result is it will cost us more money to change our engines and add about 20 pounds to the front of the car. I don't understand NHRA's logic, except that it will cost us more money to get the same result in a combination that hasn't run within a tenth of a second of the SS/FA record, set by a Chevy.
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With all due respect, this simply isnt true. One of the "natural" advantages of a 455 Pontiac is that it has a 6 5/8 rod 10.200 deck. This allows a 455 Pontiac to have a piston with a 1.500 compression height. With a single ring motor we have short piston skirts allowing a piston to be 380 grams without the pin. I now have a pin that goes about 53 gms. This makes a complete piston with two rings pretty freaking light. (one of our only true advantages) Our stroke is 4.223.
What if you have on the contrary a 3.75 stroke motor like a 440 or a Hemi with a 10.750 deck? This is a terrible disadvantage. It makes your piston like an air compressor. I measured Rick Allison's SS/AA piston about 20 years ago and it weighed over 1000 gms. Of course he didnt have a killer light set, but if you add 1/2 the additional stroke (4.223 - 3.75 = 0.473 then 1/2 = 0.2365 inches), then you add the difference between the Pontiac's 10.200 and the Mopars 10.750......that is another 0.550.
So you get a piston that is at least 0.550 plus 0.2365 or 0.7865 shorter. Not only does this take weight out of the piston it takes weight out of the crank to balance. We always used 0.300 compression height as worth a tenth. Maybe with piston technology it isnt that much, but it isnt zero. If you want to read some good info go to Wiseco's website about piston technology and power. It is a good read.
http://www.wiseco.com/TechTips.aspx click on "forged piston technology 101"
We have been talking to Wiseco about their strutted piston. We can get a compression height of 1 inch with this new strutted piston design with a single ring motor no problem. Pontiac has a block 9.200 deck. With our shorter stroke 9.200's we can get a 3.75 stroked 400 motor pretty killer. Like I said, if NHRA wants to go there we are going to have some weird looking motors out there. Like I said, I have no problem with the BBMopar guys getting it, but we should get it too. 400 Chevy guys would have a killer short block.
Rocket block's posts I agree have been excellent! Rocket, you dont know the 1/2 of it, the truth would shock you to the core!
Lynn