It's true that diesels need to have bigger parts to put up with the extra compression. The fact of the matter is that when air compresses rapidly, it heats up. When a diesel engine compresses the air charge, it is heated enough to light off the fuel when it is injected. Basically it's neccessary to have that much compression in a diesel or it would not have enough heat to light the charge. Glow plugs give a little extra heat when the engine is cold to help the process along.

 

21:1 compression...."alky cant handle those kind of numbers"

Super stock tractor pullers run alcohol in their diesel engines when the rules allow. They are above 20:1 compression and are turbo charged on top of that.


MrHorsepower

 

That's not quite right sandneck. Compression ratio is total volume at BDC divided by total volume at TDC ie: 397+43.6=440.6 /43.6 =10.10:1
Methanol should handle 21:1 however I have not personaly run methanol at more than 18:1 but we run C14+ at 16+:1 on 2 strokes
Dynoray

 

I recall a 16:1 piston being for sale On that Dune site. My head porter said that he ran alky on sprint cars running 16:1 compression with no problems.

 

V and H bike is 2800cc...... The crotch rockets are limited to 1600cc.... The Pro Stock bike do NOT run Nitro....

 

Yep ... Here is the accepted fuel list:


NHRA Accepted Fuel List
COLOR
CITGO
CITGO 110 Light Red
ERC
A19DL Pink
A19DLR Pink
DLX Pale Blue/Blue-Green
KOCH
Power 110 Light Blue
TORCO
Mach 110 Purple
Mach 112 Blue
Mach 114 Light Purple
Mach 116 Light Green
Mach 118 Red
UNION 76
76 Competiton 110 (Stock) Red
76 Super Stock 114 Orange
76 Pro Stock 118 Yellow
VP
VP-110 Purple
C-10 Clear
C-11 Yellow-Orange
C-12 Green
C-14* Yellow
C-14+ Clear
C-15 Green
C-16* Blue
C-19* Yellow
C-23** Blue
C-25* Yellow
PHILLIPS 66
B25 Clear
B32 Light Blue
B33 Light Green
B37 Red
SUNOCO
Standard Purple
Supreme Light Blue
Maximal Light Red

 

Compression ratio is simply the volume above the piston at Bottom-Dead-Center divided by the volume above the piston at Top-Dead-Center.

Most Pro Stock bikes are running 13:1 compression ratio. The spec sheet was probably mis typed. Heck, the commentators don't know what c.r. they're running and most of the riders don't even know. Now, they would like to run more, but the trade off on horsepower isn't worth it. The valve pockets in the pison are the limiting factor, and higher lift cams are worth more horsepower than more compression ratio. The horsepower gains beyond 16:1 get smaller and smaller. It's just my opinion that your money is better spent on other things to get faster than trying to go above 16:1 compression and all the complications that go with it.
Good to be able to answer something!
222

 

Well I agree that CAM profiles,and port work is where the real H.P. is

Soooo it sounds like the a race engine should be biult around the CAM?? atleast on natural aspirated engines.


Ever notice how engine biulders are like Majicians? They NEVER tell thier secrets


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True power lies in the head - cams and valves. The rest should be kept at a decent compression ratio and as light as possible so they rev like mad.

As a reference, think about the difference they can gain from pulling a stock head off a 11:1 SBC and going to a say Edelbrock aluminum head. The % gains are incredible. Add a nice cam and even more so.