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how to calculate engine displacement and horsepower
https://www.slantsix.org/forum/viewtopic.php?t=10530		 Page 1 of 1
Author:  Engine Calc... [ Thu Sep 30, 2004 12:13 am ]
Post subject:  how to calculate engine displacement and horsepower
does anyone know how to do engine calculations?

a stock 225 is 3.7L

and my pistons are .040 over. but my head is going to be shaved .060 under.

i found out i have a cast crank thats been turned 20/30

i would like to know the real displacement and compression.

and i have no idea how to figure an estimate on HP

comp cams is grinding me an "Xtreme Energy" cam with a peak of 6500 rpm

what else isnt stock? hmm the intake valves are oversized. and im going to be using a sual carb setup, yet to be determined.. and custom headers, doug got me ont he idea to make some headers, each cylinder is going to end up with its own tip :D
Author:  Super6 [ Thu Sep 30, 2004 9:36 am ]
Post subject: 
.040 over gives you 230 cid.

Compression ratio is a crap shoot without some measurements. Need to know how far the piston in 'in the hole' (piston-deck clearance), combustion chamber volume (cc the head), and compressed thickness of the headgasket you will be using.

Making the following assumptions, I come up with 9.69:1 comp ratio (like I said, this is guess at best)

'Stock' head -- 54 cc combustion chambers
'Stock' piston-deck -- .140 in the hole, -.060 mill = .080 in the hole
.039 compressed thickness head gasket.

I do not know if I would rev a cast crank slant to 6500 rpm... :shock: I have had my cast crank to 5500 with no problems to date, but I will likely never surpass that rpm because I do not want a rod (or the crank) taking vacation from its home IN the block :wink:

-S/6

Forgot to add, I have a spreadsheet that does all these calculations for you. I forget who, but another member has made one as well...and it looks a little easier to use than mine. If you want a copy of mine, PM me your email addy.
Author:  kesteb [ Thu Sep 30, 2004 12:29 pm ]
Post subject:  Re: how to calculate engine displacement and horsepower
Quote:
and custom headers, doug got me ont he idea to make some headers, each cylinder is going to end up with its own tip :D
If you poke around long enough you will eventually run across a picture of a \6 powered slingshot dragster. They tried the one pipe per cylinder header idea. The pipes were something like 6' long to get the setup to work correctly, I don't think that would be a vaild setup for a door slammer.

If my understanding is correct, some of the faster \6 cars are using the cast crank engines. To post the times they are getting, they would need to sping the engine considerably faster the 6500 rpms.
Author:  Dart270 [ Thu Sep 30, 2004 1:26 pm ]
Post subject: 
Many people have run the cast crank motors with success. Any of the racers will tell you that 6500 rpm is pushing the limit, but is possible with a well built motor. Most of the racers stay below 6500.

The fastest time for any Slant doorslammer, 9.85 @ 131 (MPH?), was done all below 5500 RPM on 12psi of boost (Drakes). The fastest times on N2O were done in the neighborhood of 6500 max. Mike J may have hit 6700 w/ his car (cast crank with custom pistons), and the Cox boys would spin 7000 (forged crank). Mike J now uses forged cranks exclusively.

Rodney Hargis (1998 Champ and this year runner up) has been using a cast crank motor (6200rpm redline?) in his '62 Lancer for years with no troubles, running in the high 12s. Car is about 2700lbs with him in it.

Lou
Author:  Baron [ Fri Oct 01, 2004 11:04 am ]
Post subject: 
thanks guys.. i was just wanting ballpark figures, im going to use stock sized connecting arms. and i dont really plan on pushing past 6000, allthough it will be well capable, and i thought 6500 was a little high when i first heard it.. but those guys at comp cams can be damned convincing.

and my bike SHOULD weigh in around 500-600 when everything is done.
Author:  panic [ Fri Oct 01, 2004 9:05 pm ]
Post subject: 
Author:  Baron [ Sat Oct 02, 2004 9:19 pm ]
Post subject: 
yeah its going in a motorcycle, and maybe i have no clue what its going to weigh and its just wishfull thinking?

you can find more on this site here
http://www.slantsix.org/forum/viewtopic.php?t=10391

or on my site here
http://www.hardymotorcycles.com


and i totally wasnt logged in when i posted this topic lol
Author:  panic [ Sun Oct 03, 2004 4:42 pm ]
Post subject: 
What's an appropriate quote to insert here?
I know: "everyone knows you're an idiot".
Author:  Baron [ Sun Oct 03, 2004 11:16 pm ]
Post subject: 
I think the only "wrong" here is your lack of imagination.
if you need help then here, read this

http://www.bacomatic.org/~dw/hdv8/hdv8.htm

the drive setup wil be almost the same as what these guys are using.
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