Crankcase vent.

[ELLESS]

Hi, what do you think about crankcase venting? Is there any Hp gains to be found there? 

[bluedog59]

Yes, not only in venting but also in aiding airflow below the pistons. Anything that helps more of the power made at the piston crown get to the rear wheel is effectively free bhp.

[ELLESS]

Do you know how, to aid airflow below the pistons?

[bluedog59]

Basically it's helping the volume displaced by a falling piston move into the volume created by a rising piston. I think the best people to ask would be those that build race engines where the rules limit what you can do. You're not going to find huge gains but lots of little bits that give you a bhp or 2 soon add up.

[ELLESS]

Allwright, i made my pistons shorter,and cut off 7mm of the cyl.Weigtsaving app.210 grams.

[bluedog59]

What engine ?

[ELLESS]

Its a 87 1054 with + 0,5 mm. bore.

[ELLESS]

Sorry, this is the one.

[baldrick]

I don't know why the Japanese factories spend so much on R & D, when clearly some bloke in his shed knows better.

why would you shorten the pistons?

why would you shorten the liners?

did you weight match them?

Are you aware that they are a specific length to prevent rocking etc?

[ELLESS]

To make them lighter, yes ,yes. This is for racing only,and no need to survive + 100000 km.

 

[bluedog59]

Are those the pistons you're using ? I'm presuming you've shortened the liners because the piston skirt no longer goes there. Do they still spigot into the cases ?

You can improve on the standard R+D where time/cost made it not worth them doing but there is nearly always a shifting compromise.

[ELLESS]

5 minutes ago, bluedog59 said:

Are those the pistons you're using ? I'm presuming you've shortened the liners because the piston skirt no longer goes there. Do they still spigot into the cases ?

You can improve on the standard R+D where time/cost made it not worth them doing but there is nearly always a shifting compromise.

To make them lighter, yes ,yes. This is for racing only,and no need to survive + 100000 km.

No i just shortened the standard ones.If you want more power you dont go standard anything.

[bluedog59]

Any chance of pictures ?

[ELLESS]

Sorry I dont want to take the cyl. off. Maybe next year after they gone kapuut. He He

[dupersunc]

I've got an ex Mistral racing 1216cc side car motor in my slabbie.

The cases have a huge amount of work to help pumping losses. The bottom if the liners have big cut outs to allow flow between cylinders and the webs have been de bured corners radiused. I've also added a big -10 breather to the clutch casing and opened up the cam cover breather.  They both go into a large catch tank/ seat support. which is vented to atmosphere via a big air filter.

I've seen healthy gains on race car engines from a good breather set-up and one engine that  lost  25bhp,around 10% ,because of a partially blocked breather.

[kingofvenus]

Prostock dragbikes use vacuum pumps. 

[ELLESS]

Very intr. info, I will fix two 1/2" holes in the covers for the starter and alt.

[Gixer1460]

1 hour ago, ELLESS said:

Very intr. info, I will fix two 1/2" holes in the covers for the starter and alt.

May not be of much benefit there due to lack of air movement! Better places are clutch chest / cover and cam cover / chain tunnel. Any blow-by (and those pistons look plenty prone) needs venting - bigger bore the better.

[dupersunc]

38 minutes ago, Gixer1460 said:

May not be of much benefit there due to lack of air movement! Better places are clutch chest / cover and cam cover / chain tunnel. Any blow-by (and those pistons look plenty prone) needs venting - bigger bore the better.

alternator blank plate and clutch cover vent the same area...

[Racer-X]

The more crankcase venting the better, as already said, I looked hard at reducing rotational mass in my race engines, including external rotation, anything the engine has to use power to turn. Food for thought may be ?

[ELLESS]

I will remove the whole starterapp. from the crank,have you tried that? Will i have problem with the balans,vibration?

[Racer-X]

Yes current engine (1127) runs with no starter clutch. No vibes from removal. Picks up revs much quicker..... if you are running total loss and removed the alternator, if you think out of the box, there's still rotational mass to lose there too!!!! That's all that I can give, can't give all my secrets away! 

[ELLESS]

13 hours ago, Racer-X said:

Yes current engine (1127) runs with no starter clutch. No vibes from removal. Picks up revs much quicker..... if you are running total loss and removed the alternator, if you think out of the box, there's still rotational mass to lose there too!!!! That's all that I can give, can't give all my secrets away! 

Yeah,I did some adj. too the bits that drive the gen.Give away all your secrets,there are only nice Suzuki fans here!

[Suban12]

On 11/1/2019 at 5:02 PM, dupersunc said:

I've got an ex Mistral racing 1216cc side car motor in my slabbie.

The cases have a huge amount of work to help pumping losses. The bottom if the liners have big cut outs to allow flow between cylinders and the webs have been de bured corners radiused. I've also added a big -10 breather to the clutch casing and opened up the cam cover breather.  They both go into a large catch tank/ seat support. which is vented to atmosphere via a big air filter.

I've seen healthy gains on race car engines from a good breather set-up and one engine that  lost  25bhp,around 10% ,because of a partially blocked breather.

Interesting info here dupersunc.Do you have any pics for reference?3 breathers on my turbo bandit but never thought about crankcase mods..food for thought for next build.....

[dupersunc]

9 hours ago, Suban12 said:

Interesting info here dupersunc.Do you have any pics for reference?3 breathers on my turbo bandit but never thought about crankcase mods..food for thought for next build.....

No sorry. The engine is built up and in my race bike now.