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#1 madaboutcherry

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Posted 19 December 2020 - 11:20 AM

finally after 12 months of blood sweat and ill health my new engine is running. it's specialist components rotrex supercharger and as it's my first forced induction engine i'm quite pleased with it, i cant wait to get it on the road

my question is, the dump valve seems to open slightly even at tickover and is venting air. is this normal?



#2 madaboutcherry

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Posted 19 December 2020 - 11:44 AM

also the boost gauge doesn't show a positive reading, if you blip the throttle it shows a negative reading.



#3 mini13

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Posted 19 December 2020 - 07:52 PM

It depends in the dumpvalve spring, but it's not impossible. The thin pipe is connected to the manifold, so at idle it will have about -7 psi trying to suck the dump valve open, when it's boosting it will have boost plus yhe spring pressure holding it shut.

Just reving it, probably won't see boost, or not much, you'll need to get yhe engine under load.

#4 Turbo Phil

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Posted 20 December 2020 - 10:32 AM

The dump valves can often be open at idle, I bought a group A type valve with a built in K&N type filter for this reason.

Phil.

#5 mini13

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Posted 20 December 2020 - 12:45 PM

Come to think of it, this is why I used a bypass type, so I could stick a filter in it!

#6 madaboutcherry

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Posted 21 December 2020 - 12:24 PM

anything like this,

 

Piston Ram Dump Valve (With Filter) | FMDVF005 | Forge Motorsport



#7 Daddy Elfrod

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Posted 28 December 2020 - 02:15 PM

I have the rotrex kit and use a blow off valve from forge. It will vent at idle or partial throttle as the engine does not need all the air that is being provided. At full throttle the blow off valve will close giving you full boost. The rotrex is relatively low boost anyway as can be fitted to the stock Mpi without mods.

#8 madaboutcherry

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Posted 29 December 2020 - 12:09 PM

I have the rotrex kit and use a blow off valve from forge. It will vent at idle or partial throttle as the engine does not need all the air that is being provided. At full throttle the blow off valve will close giving you full boost. The rotrex is relatively low boost anyway as can be fitted to the stock Mpi without mods.

thanks for that!






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