19 replies to this topic

[fredrik]

Now the bypass valve is in place, it works well...... it opens on idle and on cruise at all speeds as long as there is vacume

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[OfMini&Men]

Youll find the Bmw Mini r53 bypass valve isnt the best the seal gose hard and can jam shut or open

[fredrik]

which other cars have similar valves? that could be used instead?

[OfMini&Men]

Graham is this only on Carb'd set up?

[OfMini&Men]

 

 

 

 

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.

 

 

With carb setup?