I got bored and started calculating different cranks in a b20a block.

Heres what I came up with:

Block Crank Rod r/s Disp
B20A B16 151.75 1.97 1587076.3755cc (1.6L)
B20A B17 149.55 1.84 1706814.648 (1.7L)
B20A B18B 145.75 1.64 1834412.9535 (1.8L)

this is with the stock 81mm bore.
A 1.97 r/s ratio is temping.... because you can run more boost on it safely (read my r/s debate thread for more info on this). So ummmmm 10k rpm + 25 lbs of boost on pump gas =

Hell, ,even if u kept the b18b crank, u still get a 1.64 r/s ratio! Yes I realize you need custom rods, but it cant be THAT much money. Imagine a b20a block with a GE step deck

but.. will a b20a block bolt up to a regular b-series tranny?

 

good info, at first i thought you were doing the b20b, and i remembered that crvtec.com used to have that info.
-joanthan

 

good luck getting 25psi on pump gas.
good info though thanks for doing the math

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b16ahybrid &raquo;</TD></TR><TR><TD CLASS="quote">good luck getting 25psi on pump gas.
good info though thanks for doing the math </TD></TR></TABLE>

If a chevy 350 with longer rods can run 11:1 on 87 octane, I can run 25 psi on 93

You can probly get 20 psi on pump gas with 1.97:1 r/s. part of the theory is, the piston dwells at TDC longer, so the window of oppurtunity to ignite the fuel mixture is larger. So you can retard timign w/out losing as much power as you would with a smaller r/s ratio. Also the speed of the piston is decreased near the top of the stroke, so the mixture isnt compressed as quickly, which probably helps prevent detonation a little bit.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by UberTeg &raquo;</TD></TR><TR><TD CLASS="quote">

If a chevy 350 with longer rods can run 11:1 on 87 octane, I can run 25 psi on 93

You can probly get 20 psi on pump gas with 1.97:1 r/s. part of the theory is, the piston dwells at TDC longer, so the window of oppurtunity to ignite the fuel mixture is larger. So you can retard timign w/out losing as much power as you would with a smaller r/s ratio. Also the speed of the piston is decreased near the top of the stroke, so the mixture isnt compressed as quickly, which probably helps prevent detonation a little bit.</TD></TR></TABLE>

There is a big difference between a chev 350 runing 11.1 compression and a honda runing 25psi of boost. Sure your logic helps but you have to accont for the compression under boost. I doubt that the 350 was a stock engine (probably had different heads,cam,manifold,etc) so sure it can handle 11.1 compression..stock (heads,etc) no you'll detonate like crazy.....
Then again i can be talking out my ***.....so i'f i'm wrong...so be it........i just think that there is a big difference between the two engines.anything is possible with the rite amount of money


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by UberTeg &raquo;</TD></TR><TR><TD CLASS="quote">
Also the speed of the piston is decreased near the top of the stroke, so the mixture isnt compressed as quickly, which probably helps prevent detonation a little bit.</TD></TR></TABLE>

Explain this in a little more detail.

your hypothesis is interesting though

 

http://www.airflowresearch.com...1.htm

That the website. I may try to put a b16 crank in a b18 block and test this out

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by UberTeg &raquo;</TD></TR><TR><TD CLASS="quote">http://www.airflowresearch.com...1.htm

That the website. I may try to put a b16 crank in a b18 block and test this out </TD></TR></TABLE>