Compression ratio.

[Alex]

Hello all. I have a bandit turbo , it’s a 1216 with hayabusa pistons in. The engine is apart at the moment waiting for rebuild. My question is, what is the standard compression ratio for a mk1 hayabusa? My reason for asking is at the moment genuine Suzuki busa pistons are more expensive than e.g Wisco or je . From my understanding busa pistons drop the compression down to 8.5-1 ? This is not a race bike it’s just for the road, so looking for around 220-240 bhp only. What pistons are you guys using and where to get them? Thanks alex

[Arttu]

I think gen1 Hayabusa has about 11:1 compression ratio. But what's the point of your question? When you fit the Busa pistons into a Bandit engine the resulting compression ratio will be something completely else any ways.

[Duckndive]

The answer is called Maths ...You can do it here 

https://www.summitracing.com/newsandevents/calcsandtools/compression-calculator 

[DAZ]

So you basically want to know if you can fit a set of  je or wiseco aftermarket pistons to your bandit turbo to save a bit of cash? And can you get away with using higher compression pistons eg 13:1 in a busa would it be 10.5:1 in your bandit..... Many(most?) Use the busa pistons up to 220-260bhp @clivegtohas a couple that have been dynoed so can give you real world numbers 

26 minutes ago, Duckndive said:

The answer is called Maths ...You can do it here 

https://www.summitracing.com/newsandevents/calcsandtools/compression-calculator 

I think there is more to consider than cost and compression, such as crown shape and squish, weight, balance  etc, if I were you I'd ask someone who deals with turbo bikes like Mr Dunlop at fast by me.... He's been doing it long enough to know what works and what doesn't 

Edited December 18, 2023 by DAZ
Fat fingers vs small phone

[Gixer1460]

No one buys 'new' Busa pistons - virtually every build uses s/hand ones even retaining old rings in some cases. Keep searching Eblag and forums, they come up fairly frequently. But if going aftermarket route due to cost - why not spec the right turbo piston for what you want and not the 'wrong' one and hoping to get the right CR. And yes high comp pistons can be used with a turbo . . . . . . just add a decomp plate. I used 1186 12.5:1 pistons with a 2mm plate - very turbo friendly!

[clivegto]

Yes I used 2nd hand busa mk1 pistons and conrods with a 2mm spacer on the bottom of the block. From memory the compression was just less than 10 to 1. Last one is making 260hp, 147 ft-lbs torque at 14 1/2 lb boost. 

Bad memory 8:1

Edited December 21, 2023 by clivegto

[slayer61]

On 12/18/2023 at 9:56 AM, clivegto said:

Yes I used 2nd hand busa mk1 pistons and conrods with a 2mm spacer on the bottom of the block. From memory the compression was just less than 10 to 1. Last one is making 260hp, 147 ft-lbs torque at 14 1/2 lb boost. 

Because I don't know, and I'm not afraid to ask... with this combo of parts, what did you end up for a deck height after adding the 2mm spacer?   

[clivegto]

3 hours ago, slayer61 said:

Because I don't know, and I'm not afraid to ask... with this combo of parts, what did you end up for a deck height after adding the 2mm spacer?   

0 busa rods are longer than B12.