Just me thinking agian....

I was watching the Pro-stock bikes run on TV this weekend,and they gave a quick Spec sheet on the Motors. These bikes are normally aspirated,and the run 21:1 compression!!! WOW!


How in the heck are they doing that?? and is it possable to get a DS motor close to that??





BIgger.

 

somone correct me if I'm wrong, but I think diesel engines are running in that vicinity or more. But as far as the 4-cycle engines, I've never heard of that, but I guess it's possible.

 

Most modern turbocharged 4 stroke diesels that I've seen specs on are around 16:1 compression ratio. The old 2 stroke Detroits were more like 21:1. With that much compression what fuel are they useing? With gasoline I would think the heat caused by the compression would ignite the fuel long before the spark plug did. So I'm thinking you would need a fuel that ignites at a much higher temp. But I haven't researched it so I could be wrong.

 

Bigger, did it say whay kind of fuel they were running?

 

I just assumed they were runnig Alky, but I dont know if NRHA allows the Bikes to run Alky or not.



I just cant seem to comprehend how one could get the piston that far up into the head to get such High compression . I wonder what the Piston to valve clearances are???




Bigger.

 

Bigger,
Whos bike was it? Was it a Suzuki or a Harley?

 

That was for all racers, but I dont know if the Harleys were Running that high or not. The Guy was just giving the Spec on all the motors in Prostock. He gave BORE, STROKE and Compression. and it sounded like all in-line 4 motors had to be all the same. I'm sure the the Harleys were differnt though. those Harleys are IMPESSIVE!!!



Bigger.

 

Antron Brown runs VPC25 in his. I don;t know what the spec is on that, but I am sure somebody can look in to it.

 

I know those top fuel harleys run insane amounts of compression. Guess thats why they run the NitroMethane.

 

don't think i'd want to sit on top of that, the pop might have some bad side effects.