Pneumatic paddle shift system considerations

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mefmotorsport
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Pneumatic paddle shift system considerations

Post by mefmotorsport »

Hi All,

I have a pneumatic paddleshift system on my rally car controlled by an S100 ecu.

The system worked fine but recently a scrutineer objected to the compressed air vessel in the back of my car exposed to the occupants! Its a hand held fire extinguisher pressurised to 10bar.

I decided to make a box in the boot floor and box it in along with the compressor which results in a much neater installation, all hidden away from prying eyes of scrutineers!

Anyway I've done all that now and just about the try it all out again after completely re-piping the system.

The thing I need to discuss is to do with the air solenoid valves and their location in respect to the gearbox operating air solenoid.

Previously I had the two solenoid valves very close the operating solenoid, say 300mm pipe lengths (6mm o/d plastic push fit tube). Now I have relocated them to the new box with the compressor and the air feed pipes are now 2500mm long.

The question is, do you think the longer length of the pipes will cause the operating solenoid to be more sluggish/slower operating the gears?

any comments welcome!

martin
steveslowboy
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Re: Pneumatic paddle shift system considerations

Post by steveslowboy »

In the few systems I've setup, the advice was always to keep the air hoses from solenoids to actuator as short as possible.
I'm sure some tweaking of your setting should reduce any sluggishness to manageable levels.

I'd swot up on the blue book If I were you so next time you can "Discuss" with the scrutineer where he thinks it says you can't have the bottle in the cabin.
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mefmotorsport
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Re: Pneumatic paddle shift system considerations

Post by mefmotorsport »

steveslowboy wrote:In the few systems I've setup, the advice was always to keep the air hoses from solenoids to actuator as short as possible.
I'm sure some tweaking of your setting should reduce any sluggishness to manageable levels.

I'd swot up on the blue book If I were you so next time you can "Discuss" with the scrutineer where he thinks it says you can't have the bottle in the cabin.
OK, yes I suspected that would be the case.

I've learned from past experience that its best not to argue with scrutineers, just take on board what they're saying and either act upon it or not!

I did ask the scrutineer how I stand with 3 fire extinguisher bottles pressurised to similar or more pressure being inside the car, he said they were OK !


I'll try it first and see how it performs.
katana
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Re: Pneumatic paddle shift system considerations

Post by katana »

Example on pipe length effects - we used an air shifter on a dragbike and having a sequential gearbox needed a shift kill to unload the gears to allow shifting. Its was accomplished with a air switch that was teed off the shift soli to ram line - it had to be precisely 6" longer hose length compared to the soli / ram hose. this allowed pressure to build on the ram with delay to the ign kill so it killed exactly as the ram moved the gears. I think you'll notice the extra length of hose!
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mefmotorsport
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Re: Pneumatic paddle shift system considerations

Post by mefmotorsport »

OK thanks, well if that's the case and it noticeably slows down the shift I can quite easily relocate the 2 air solenoid valves back by the gearbox where they were originally. the same 2 pipes will be always charged with compressed air but on the input side of the valves as before.
stevieturbo
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Re: Pneumatic paddle shift system considerations

Post by stevieturbo »

mefmotorsport wrote:
steveslowboy wrote:In the few systems I've setup, the advice was always to keep the air hoses from solenoids to actuator as short as possible.
I'm sure some tweaking of your setting should reduce any sluggishness to manageable levels.

I'd swot up on the blue book If I were you so next time you can "Discuss" with the scrutineer where he thinks it says you can't have the bottle in the cabin.
OK, yes I suspected that would be the case.

I've learned from past experience that its best not to argue with scrutineers, just take on board what they're saying and either act upon it or not!

I did ask the scrutineer how I stand with 3 fire extinguisher bottles pressurised to similar or more pressure being inside the car, he said they were OK !


I'll try it first and see how it performs.
A wise decision ! And often the rules and scrutes are not so wise in their implementation.

I'd imagine the shift uses very small blasts of air in operation so a 2.5m long pipe will hold a substantial volume that needs filled before anything happens.
I'd defo get them as close to the box as possible.

Unless you could add some sort of check valve that might hold some residual pressure in the line, although that then might reduce actual pressure available at the shift mech too.
Rob Stevens
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Re: Pneumatic paddle shift system considerations

Post by Rob Stevens »

Don't forget that the actual shift cut time is determined by the gear position sensor not the start of air like the system mentioned by katana above.
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mefmotorsport
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Re: Pneumatic paddle shift system considerations

Post by mefmotorsport »

Rob Stevens wrote:Don't forget that the actual shift cut time is determined by the gear position sensor not the start of air like the system mentioned by katana above.
yes, he seems to have a non-electronic cut system based on air speed which is very different.

Hopefully I will get a chance to drive it today and see how it compares shift wise with how it was before. Its no big deal to put the solenoids back where they were before, its just that they are exposed to the elements since they are not enclosed in a container, thats why I moved them into the new compressor/air receiver housing in the back.
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Re: Pneumatic paddle shift system considerations

Post by stevieturbo »

Even just move them up inside the car beside the tunnel and just route the hoses out through ?
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Re: Pneumatic paddle shift system considerations

Post by Mr Drew »

steveslowboy wrote: I'd swot up on the blue book If I were you so next time you can "Discuss" with the scrutineer where he thinks it says you can't have the bottle in the cabin.
My guess would be a miss interpretation of section j rule 5.2.1
mefmotorsport wrote: I've learned from past experience that its best not to argue with scrutineers, just take on board what they're saying and either act upon it or not!
True, they're always right, even when you get the blue book out and prove them wrong!
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