Dan/Bob, I hate like heck to call you guy`s out on this and I know we have talked, but i`m in the process of assembling two Hemi`s for the PSMCDR and neither guy wants to order pistons until they hear an "offical announcement" from the leaders themselfs reguarding the new compression rules. Your race is closing in and i know several guy`s who are stuck in this position. I`m respectfully asking to please post something soon. Thanks
I read the message that Bob posted above regarding rules changes. I realize that the revisions are not complete, but I am wondering if you (Dan & Bob) plan any changes to the exhaust system rule ?
So Bob, would the answer to Daves question be....... if building a 10.25 to 1 factory rated street Hemi, you could add 1.5 points for a total of 11.75 to 1, correct? Won't this rule actually give some engines MORE compression than they would've been able to achieve using NHRA blueprint specs??? It's going to help some,hinder others?
This new rule would actually give my '68 RAII engine a HIGHER allowable compression ratio of 12.25 to 1 (10.75 plus 1.5 points) than the maximum NHRA legal ratio of 11.65 to 1! The 11.65 to 1 ratio is based on: 4.190" NHRA max. bore (4.120" + .070" overbore) 3.765" NHRA max. stroke (3.759 + .015" tolerance) 4.190" bore x 3.765" stroke= 51.914 cu. in./ cylinder (415.3 CID) 65cc NHRA min. combustion chamber volume= 3.966 cu. in. .042" NHRA min. head gasket thickness volume= .581 cu. in. .000" NHRA min. deck height volume= .000 cu. in. 5.3cc NHRA min. piston valve relief volume= .323 cu. in. Total chamber volume= 4.870 cu. in. 51.914 cyl. vol.+ 4.870 chamber vol.= 56.784 / 4.870= 11.659 to 1 NHRA max. compression ratio. Does this mean I can run a thinner head gasket and smaller combustion chamber volume to get closer to the 12.25 to 1 ratio?
My point exactly:Smarty: Every 71-74 Buick 455 will now be able to go from 8.5 to 1 advertised up to 10 to 1. WOW a 69 Stage 1 400 was factory rated at 11 to 1:Smarty: I wonder what a stripped down 12.5 to 1 69 GS400 will run:eek2: Now I know what to start looking for:Brow:
Tom/Jim/Tom Our new rule for 2011 states that you will be allowed to run 1.5 points over advertised compression. Yes, some cars will benefit from the new rule, but we feel that our compression chart offers a more equal playing field. And as far as NHRA goes, well lets just say there were a lot of reasons why we had to terminate their guide lines. And were not going to get into a lengthy debut about why we did. Bob & Dan
I'm just looking forward to bringing my 1970 383 Charger that is still in the same configuration that it was in 1986. It may not be the fastest, but when I make the 6-way seat break loose on the launch, I will have a smile on my face ..... just like the old days. If I can break a 15 second pass with it, I will be happy. I must be getting old if I am talking about the "old days" ...... :eek2:
So are you saying every combo can be 1.5 over regardless of deck height etc or are you saying if all your specs are legal you can still only be 1.5 over? Example my 74 360 duster uses a dished piston thats supposed to be .070 in the hole(I think)and has and advertised compression of 8.4:1.With the new rule can I now run a flat top piston with zero deck height as long as I'm not over 9.9 compression?
So now you dont care how we get the compression as long as it is just not more than 1.50 over what stock was? So technically I could run a quench dome piston and be good?
Tom, given Bob and Dan's clear intent for this race and the rules, what makes you think this bold-face rule would be changed: I don't see how adding a dome or improving the piston's quench design could be considered "original."
All this hand wringing and expense just to race someone with a car just as fast as your car....... I'm more concerned with the removal of MSD boxes (and such). Are the tech directors going to be looking under the dashboards of every car??? The four gear guys are going to HATE this rule change taking away their rev limiters.
I'm just trying to understand this rule change. It would seem to me both a 340 and a 440 would pick up another .5 of a point of compression and while "I wouldn't cut my castings" beyond the NHRA engine blueprint spec I'm sure some will. I'm just trying to figure out how they would do such a thing. I personally won't build anything stock stroke that wouldn't be NHRA legal in case this parking lot party goes poof! Having good legal parts just ensures my future racing endeavors are cheaper.
I've just read the "new rule" plus all the responses, and all that comes to mind is... here we go again! :Smarty:
Who needs a rev limiter or a shift light?????? Maybe missed one shift in so many years!!!:3gears: :blast:
Pure Stockers Let us give you example of what we are talking about with the new compression rule. If Jim Mino's R.A.II has a advertised compression ratio of 10.75. At 1.5 over advertised he is allowed to run 12.25. It's up to Jim how he gets to that maximum limit. He could cut his heads, run a thinner head gasket, or use a small dome piston. We hope that clears up the new rule on compression. As for the ignition boxes, we don't need them. Again a small few ruined it for the majority. Were not saying you can't run a rev limiter, but your going to have to switch to the unit that goes underneath your distributor cap. Thanks Tom & Roberta for jumping in with your opinion on rev limiters. Bob & Dan
