Stroker Kits

[civic_ferio]

hi. i was just wondering how does it work? can you cange the displacement just by changing the crank shaft?

 

[Slo86GT]

it's all about the math.

If you increase the stroke on the crank, the piston will push further upward, so you either:

A: get a shorter rod and shoot the rod/stroke ratio to shit

or

B: Move the wristpin in the piston upward, possibly causing oil management or compression issues.

It's really a tradeoff, but alot of companies are making some nice stroker kits now for B series cars that have a decent Rod/Stroke ratio, while they increase displacement .1-.2 liters.

 

[civic_ferio]

so you can just increase the displacement of the engine without reboring it?

 

[phunky.buddha]

Yes, but at the cost of a lot of those stroker kits on the market, it might be cheaper (or the same price) to bore out larger and run custom pistons. Your engine will be stronger with a new sleeve built to handle the larger bore too.

 

[K2e2vin]

heres the equation for displacement: (B/2)²*pi*S B=Bore, S=stroke. if you change the stroke, the total would be greater.

ie. B16a2.. (8.1/2)²*pi*7.7= 397.78*4 (for 4 cylinders)= 1587cc
r/s= 1.74
throw in a b17 crank... (8.1/2)²*pi*8.14=419.45*4= 1678cc
your r/s ratio will decrease though, r/s= 1.62 (this is still pretty good)
or you can change the bore.... b16a2 84mm rebore=
(8.4/2)²*pi*7.7=426.72*4= 1707cc, you get same r/s ratio but more displacement.

combine them... b16a 84mm rebore, b17 crank=
(8.4/2)²*pi*8.14=451*4= 1804cc

 

[saturn_boy96]

how are you getting the rod to stroke ratio?

 

[NoJokE]

Originally posted by K2e2vin@Apr 5 2003, 01:46 PM
(B/2)²*pi*S B=Bore, S=stroke.
(8.1/2)²*pi*7.7= 397.78*4 (for 4 cylinders)= 1587cc

why do you represent bore as 8.1 and stroke as 7.7?

 

[phunky.buddha]

Originally posted by saturn_boy96@Apr 5 2003, 01:25 PM
how are you getting the rod to stroke ratio?

Know the rod lengths, divide by stroke length.

 

[phunky.buddha]

Originally posted by TypeRcivic+Apr 5 2003, 01:32 PM-->

K2e2vin

@Apr 5 2003, 01:46 PM
(B/2)²*pi*S B=Bore, S=stroke.
(8.1/2)²*pi*7.7= 397.78*4 (for 4 cylinders)= 1587cc

why do you represent bore as 8.1 and stroke as 7.7?

Centimeters... since we calculate displacement as cubic centimeters, not cubic millimeters. It's just easier to start with the right measurement scale than try to convert it later and get confuzzled.

 

[K2e2vin]

Originally posted by Calesta+Apr 6 2003, 10:38 PM-->

Originally posted by TypeRcivic@Apr 5 2003, 01:32 PM
K2e2vin

@Apr 5 2003, 01:46 PM
(B/2)²*pi*S  B=Bore, S=stroke.  
(8.1/2)²*pi*7.7= 397.78*4 (for 4 cylinders)= 1587cc

why do you represent bore as 8.1 and stroke as 7.7?

Centimeters... since we calculate displacement as cubic centimeters, not cubic millimeters. It's just easier to start with the right measurement scale than try to convert it later and get confuzzled.