G13 cranks? whats the difference?

[built4thrashing]

Can anyone tell me the differences between the G13a and G13b cranks?

Does the G13b (1324cc) have a longer stroke?

And will using a G13b crank in a G13a block with G13a pistons increase compression and if so by how much?


cheers B4T

[Santos]

g13a 77mm crank
g13ba 75.46mm
both about 7kgs

g13b 75.46mm about 10kgs

i havent been able to confirm it but apparently the a/ba pistons have different pin spacing,which would mean that ba pistons with a 'a' crank you would be getting like 0.2 points or so by cramming that extra 6.5cc's per cylinder

still if you chasing compression why not just get 9.5:1 flat tops
(which might be closer to 9.7)

[built4thrashing]

not after more compression just curious as to the differences.

Have just rebuilt a G13A but the crank was stuffed so i used a G13B crank instead. And the first test drive it it is pinging alot on acceleration. so thought it might have up'd the compression slightly.


B4T

[Santos]

on teamswift heaps of people run 10:1 shaved heads etc type compression.

i 'd say the pinging is somehing else.

you may have just shifted the g13a powerband up 500rpm by using the g13b crank ( Cast/forged?) its something i noticed when comapring engine specs g13a had peak power at 5500rpm and g13ba at 6000rpm.

[built4thrashing]

so where does the G13B get its increased capicity? can only be in the stroke as bores and rods are the same. I know the pistons are different but what sits higher up in the bore on TDC

[Santos]

your mixing the numbers up

g13a is the 1324cc
g13b, g13ba is the 1298cc motors

so if you put a g13b crank in a g13a engine you are downsizing it. (and if its a forged gti crank your adding 50% more weight to the spinning parts)
inshort anyone tossing a g13a bottom end, i want your damn crank

[built4thrashing]

oops my bad
had too many scotches already....
we put the 1324cc crank into a 1298cc motor. what is the end result in CC's and compression. just a guess?

[Santos]

at a guess standard bore
with dished pistons? 9.1
with flat tops? 9.7

(not talking about the valve notches)

which means you may have shifted your powerband down and gained yourelf a massive 2 to 3nm peak torque

hey in a suzuki 1.3l everything counts

[zook4fun]

are the plug gaps right? is it timed right? to advanced will make it ping

they are the to main things (plugs and timing) to make a engine ping under light load (not flat to the floor)

the little bit of extra comp you might have to go the next step up plugs or open up your gaps a little bit

[built4thrashing]

it pings on medium to heavy accel.

apart from the flat top and dished pistons is the longer stroke the only difference in the two motors or are the pistons different heights?
B4T

[zook4fun]

pistons have different heights as well can't remember what one has the lower pins. i think its the a pistons