19 replies to this topic

[fredrik]

Is anybody using one? thought it might make fuel economy a bit better by bypassing the supercharger on part throttle and make the car role on a bit better when you let off the throttle,

 

the eaton mprange has them and most other cars seem to have seperate one?

 

 

[hustybusty]

Would be handy for noise checks at tracks too.

[Gr4h4m]

In suck through cars, a bypass would help with sucking too much fuel on over run and asking the car to stall when come to a junction after giving it some...

[hustybusty]

So how does that work. Off the shelf part? Fitted where?

[fredrik]

search supercharger bypass valve, its on the bmw mini r52, and built in to the eaton mp45s as in thte moss kits, it opens on vacuum so om idle and small throttle amounts the intake air is bypassed the supercharger,

[Waitey]

In suck through cars, a bypass would help with sucking too much fuel on over run and asking the car to stall when come to a junction after giving it some...

 

Wouldn't work in suck through as you never create enough vac pressure in the inlet manifold.

 

search supercharger bypass valve, its on the bmw mini r52, and built in to the eaton mp45s as in thte moss kits, it opens on vacuum so om idle and small throttle amounts the intake air is bypassed the supercharger,

 

Just buy the R53 item from a mini, its only around £40.

[Gr4h4m]

In suck through cars, a bypass would help with sucking too much fuel on over run and asking the car to stall when come to a junction after giving it some...

 
Wouldn't work in suck through as you never create enough vac pressure in the inlet manifold.

 
I beg to differ , the sc causes massive vac at the inlet (between the carb and the charger) as its still pulling why you shut the throttle.the net effect is it draws a huge amount of fuel making the engine cut out... The eaton has one built in. My sc12 doesn't and I had to install one....

[hustybusty]

This makes sense to the fuel pooling, air filter side of the butterfly on the carb of my suck through set up. I'll have to have a google as I can't think how the bypass works

[Waitey]

 

 

In suck through cars, a bypass would help with sucking too much fuel on over run and asking the car to stall when come to a junction after giving it some...

 
Wouldn't work in suck through as you never create enough vac pressure in the inlet manifold.
 

 
I beg to differ , the sc causes massive vac at the inlet (between the carb and the charger) as its still pulling why you shut the throttle.the net effect is it draws a huge amount of fuel making the engine cut out... The eaton has one built in. My sc12 doesn't and I had to install one....

 

 

I'm talking about vac in the inlet manifold. Which is where you would normally draw the vac from to open a bypass valve. A bypass valve is not built in on a M45. Its designed to stop the charger making pressure when the throttle is closed on either a post charger TB or dual TB set up. Thus prolonging charger life, lessening parasitic draw and keeping the whole thing a lot cooler as well as eliminating idle droop. As pushing air at a close throttle plate doesn't get you far on over run.

 

Suck through has a whole host of issues that a bypass couldn't fix, you couldn't use the vac between carb and charger as vac exists there all the time, regardless of plate position, you'd end up with a bypass locked open.

 

See here:
http://www.mx5forum....mg_0031_189.jpg

The mini valve uses inlet vac to open the valve (black thing) to take air from post charger and dumps it post TB but pre charger. Bare in mind there will also be a 2nd TB post charger to to limit throttled volume. So this allows the charge to turn with minimal resistance during closed throttle situations.

Edited by Waitey, 09 October 2013 - 09:05 PM.

[Waitey]

The ideal mini set up with carb would be:

 

Air filter, Dummy carb/Throttle body, Bypass valve, Charger, Bypass outlet, carb, inlet manifold.

 

So essentially a blow though but with a second tb before the charger and a bypass valve fitted.

 

This system would allow for most efficient use of the charger, although you'd have to mount it at the front of the bay. It'd also give you an option to intercool the charge. 

[fredrik]

ive ordered a bmw mini one and will see if it works or not and will mount it where the bov is and test taking the vacuum from the inlet manifold where the vacuum advance and the boost guage is connected

 

 

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[Waitey]

I'm unsure what the purpose of the current blow off valve is?

[Gr4h4m]

In suck through cars, a bypass would help with sucking too much fuel on over run and asking the car to stall when come to a junction after giving it some...

 
Wouldn't work in suck through as you never create enough vac pressure in the inlet manifold.

 
I beg to differ , the sc causes massive vac at the inlet (between the carb and the charger) as its still pulling why you shut the throttle.the net effect is it draws a huge amount of fuel making the engine cut out... The eaton has one built in. My sc12 doesn't and I had to install one....

 
I'm talking about vac in the inlet manifold. Which is where you would normally draw the vac from to open a bypass valve. A bypass valve is not built in on a M45. Its designed to stop the charger making pressure when the throttle is closed on either a post charger TB or dual TB set up. Thus prolonging charger life, lessening parasitic draw and keeping the whole thing a lot cooler as well as eliminating idle droop. As pushing air at a close throttle plate doesn't get you far on over run.
 
Suck through has a whole host of issues that a bypass couldn't fix, you couldn't use the vac between carb and charger as vac exists there all the time, regardless of plate position, you'd end up with a bypass locked open.
 
See here:http://www.mx5forum....mg_0031_189.jpg
The mini valve uses inlet vac to open the valve (black thing) to take air from post charger and dumps it post TB but pre charger. Bare in mind there will also be a 2nd TB post charger to to limit throttled volume. So this allows the charge to turn with minimal resistance during closed throttle situations.

To other readers of this post
I take the vac feed from the inlet manifold. I have an LPG petrol valve that it operated by the megajolt at high vac that switches a 6mm line between the inlet manifold and the carb manifold. This stops the heavy draw of fuel when you snap the throttle shut and come to a stop. This heavy draw was causing the engine to flood and stall. I found this issue after a load of testing and a wide band on the road. It only happens on the road and not on the rollers, but then that's due to the differance between real driving and simulated. I run a Toyota sc12 suck through kit.

I did wonder why the eaton kits never seem to have this issue. After some googling I read that they have a built in valve.

Anyway not intrested in getting into a technical argument about , I can only state what has worked in my setup.

[fredrik]

The blowoff valve does nothing but i did try running blow through and it was there as a precaution only..,

Graham, its only the MP45 superchargers that have the bypass valve built in so i dont know what happens on the jonspeed and vmax kits.

mp45s are found on the moss kits, mossmotors.com and look at the mgb's and sprites

[Spaceibiza]

The ideal mini set up with carb would be:
 
Air filter, Dummy carb/Throttle body, Bypass valve, Charger, Bypass outlet, carb, inlet manifold.
 
So essentially a blow though but with a second tb before the charger and a bypass valve fitted.
 
This system would allow for most efficient use of the charger, although you'd have to mount it at the front of the bay. It'd also give you an option to intercool the charge.

What's the benefit of having a dummy throttle body before the charger?