33 replies to this topic

[Nev]

Ok, so who knows how the clutch is engaged on the Eaton SC'ers please? Full details please, with any "foibals" it may have in practice.

 

Firstly, is it electronic or vacuum based?

 

Secondly, can the clutch be semi engaged, I.e. 25%, 50%, 75% etc etc depending on either variable electrical trigger signal or variable vacuum signal.

 

Thirdly, if the signal is electrical, what's the min/max (off/on) voltage range please?

 

Has anyone got a compressor map for the M62 or a slightly smaller Easton SC please?

 

Thanks.

Edited by Nev, 20 July 2015 - 10:23 AM.

[Rosssco]

There is no clutch on an Eaton M62, only a bypass valve to allow air to free cycle and reduce parasitic loss under low loads conditions.

 

The bypass valve / actuator is vacuum operated.

[Chris P Duck]

This shows it quite well.

[steve-m-uk]

The old merc eaton m62's had an electrically actuated clutch on the pulley, i have one somewhere , i'll dig it out.

[slindborg]

could probably change the snout to get the merc clutch in

[Scuffers]

As said, Merc had clutched ones (not sure ever on the 62's though?) the SL500 was one, suffered clutch slip and failures if driven hard though.
 
Compressor maps (these are the 5th gen ones, as in later than the ones used on the VX)
 

[fezzasus]

The same as the clutch in an air conditioning compressor, however as noted above not all of them have them. The LSJ Eaton M62 doesn't, neither does the 1320 LSJ Harrop, it's really only included to minimise parasitic loss where there's a drive for fuel economy.

Edited by fezzasus, 20 July 2015 - 12:41 PM.

[Rosssco]

could probably change the snout to get the merc clutch in

 

Means you could have a Mad Max style red pull button to activate the SC..

 

Saying that, with the unit de-clutched, how would the engine breath normally? You'd just have some very restrictive rotors in the way..  

[Nev]

Thanks for the input so far.   Is the bypass valve integral in the casting or is it a separate part that fits into a housing on the casting? If so is there access/ability to change the opening spring setting on it presumably?    From those maps, the M45 would suit better, as I'd be bypassing it by 4000 RPM. What I want is masses of boost at 1000 to 4000 RPM, after which the SC will be bypassed and the  turbo will be doing the puffing. With this in mind, how much vertically higher can I expect the pressure ratio to go up on the Y axis if I select a very small pulley?

Edited by Nev, 20 July 2015 - 12:52 PM.

[fezzasus]

It's a separate vacuum driven actuator, just like a turbo actuator. However it doesn't reduce parasitic loss much (if at all) because it doesn't declutch the rotors from the pulley. It's mainly there for NVH as it prevents boost surge when off throttle. Therefore it is binary in action.

Edited by fezzasus, 20 July 2015 - 12:48 PM.

[Rosssco]

Thanks for the input so far.

 

Is the bypass valve integral in the casting? If so is there access/ability to change the opening spring setting on it presumably? 

 

The actual bypass butterfly valve is integral to the SC casing, yes.

 

The vacuum actuator is external obviously. If you wanted to change the actuation point, you would just fit the standard solenoid as fitted in the original LSJ engine application (we don't use it on VX220 applications as the ECU can't operate it). This would mean you could electrically control the bypass actuation as you would with a turbo.

[Nev]

The actual bypass butterfly valve is integral to the SC casing, yes.

Does anyone know the diameter of the aperture please, I need to estimate the flow calc at full chat. Am I right in thinking the hole is perpendicular to air flow (ie mounted on the side wall of the casting)?

Edited by Nev, 20 July 2015 - 12:57 PM.

[Rosssco]

I'm not able to directly post photos, but see link below where you will see the underside with bypass port / valve.

 

http://www.cobaltss....9_5017912_n.jpg

[The Batman]

Nev,

Bypass valve bolts on here and uses that outlet for the pressure





Hole size is 39mm

[Nev]

I'm not able to directly post photos, but see link below where you will see the underside with bypass port / valve.   http://www.cobaltss....9_5017912_n.jpg

Thanks Ross. Unfortunately that aperture looks far far too small for compound charging. I'd have to supplement it with some other larger bypass system.

[CocoPops]

Would a Rotrex SC not be better suited to compound charging rather than the Eaton?

[fezzasus]

Would a Rotrex SC not be better suited to compound charging rather than the Eaton?

 

Yes, and at that point you may as well throw away the turbo and just fit a massive Rotrex SC as you've already got past the issue of inertia. 

[Nev]

If someone could answer my previous question please, I'd be grateful: RE: M45 "How much vertically higher can I expect the pressure ratio to go up on the Y axis if I select a very small pulley?". What is the smallest pulley that can be driven by the 5 point belt without it slipping BTW? Whats the normal diameter of the drive pulley for the crank also. And lastly, does anyone have an old M45 they could lend me please? It doesn't even need to work, just need it for estimating fit potential. Thx.

Edited by Nev, 20 July 2015 - 01:25 PM.

[fezzasus]

No one uses M45s on VX220s, you'll be best searching some Mini forums. Belt slip isn't the issue, it's max rated bearing speeds. I know JLR have had problems pushing superchargers too far.

Edited by fezzasus, 20 July 2015 - 01:25 PM.

[Scuffers]

 

I'm not able to directly post photos, but see link below where you will see the underside with bypass port / valve.   http://www.cobaltss....9_5017912_n.jpg

Thanks Ross. Unfortunately that aperture looks far far too small for compound charging. I'd have to supplement it with some other larger bypass system.

 

some notes:

 

if your looking to compound charge with a M62, then using the by-pass to turn-off the SC works just fine, remember, your not trying to move all the air-mass though the by-pass, only to 'spill' the overcharge.

 

this is what I did with Jamie's Exige, worked very well, and it-s by-pass is only 34mm (external to the SC - the MP62 that's used on the VX it's internal).

 

one difference of it being external is that the by-pass air still goes through the intercooler core, this can be a good and bad thing, depending on what the thermal loading is like.

 

Last thing, if you're going to do this setup, the turbo compressor needs to be picked carefully, as the PR you're expecting it to work over is much wider than for a simple turbo install.