Mazda Rotary Club

Cars by Model Type => 3rd generation RX-7's => Topic started by: D1 WTF on June 08, 2006, 11:41:49 PM

Title: How about dump valves
Post by: D1 WTF on June 08, 2006, 11:41:49 PM
i often ask questions as everyone seems to be able to answer me.
i am running stock twin turbos, what is the deal with dump valves.  i thought the rex was a recirculating system therfore thought DV\'s would mess this up.
and now i have been told that there is dump valves on there just standard just silent.

can some one enlighten me please, how many other people are running them on twin t\'s.
cheers  :wave
Title: How about dump valves
Post by: vxer on June 09, 2006, 01:48:18 PM
The RX7 has a recirculating dump valve, but the ECU does not measure air mass, so it doesn\'t matter if the dump valve is redirected to vent to atmosphere.

Arguably, there is a performance drop associated with dumping to air, because you\'re losing pressure - however, its hot air that you lose, so maybe it doesn\'t matter.

Cheers, Paul.
Title: How about dump valves
Post by: D1 WTF on June 09, 2006, 08:28:26 PM
well that is what i thought, it would produce a pressure drop.  but i wondered what effect this has on performance etc
Title: How about dump valves
Post by: Grizzly on June 09, 2006, 08:46:12 PM
I always thought the only diffrence between Oe and aftermarket BOV\'s is the amount of Boost presure it can handle without leaking?

BOV\'s are an Old subject, Its said the Bov helps the soften the blow when the throtle is Shut during gear changes and provides an exit for the extra boost that would still be pushed in by the Turbo, But if you have one of the Big shaft single turbo\'s you can easy run your car with no BOV fitted... Plus if your just after the BOV noise running no BOV you can hear the wastegate Chatter :)
Title: How about dump valves
Post by: Rixio on June 10, 2006, 12:52:23 PM
Iv got recirc valves and was wanting to change to an aftermarket one but didnt know if it would make any difference because Pip said youd rather have recirc over BOV as they work more efficiently. I like the sound of a BOV though  :Laugh
Title: How about dump valves
Post by: D1 WTF on June 11, 2006, 02:19:43 PM
Quote from: RixioIv got recirc valves and was wanting to change to an aftermarket one but didnt know if it would make any difference because Pip said youd rather have recirc over BOV as they work more efficiently. I like the sound of a BOV though  :Laugh

so how do we find out the power loss etc or the real advantages/ disadvantages

some one on here must know?  "help please"
Title: How about dump valves
Post by: McCARTHY on June 11, 2006, 02:33:42 PM
the only way to see the power differences would be on a dyno. one run with stock, then run re-cerc and then run  then atmospheric all on the same car so no other factors can change the readings
Title: How about dump valves
Post by: D1 WTF on June 11, 2006, 04:02:15 PM
yer but will end up being a little expensive.  wonder if any one knows this already such as dragon etc
Title: How about dump valves
Post by: McCARTHY on June 11, 2006, 04:11:32 PM
yeh it would be a pricy test.
Title: How about dump valves
Post by: D1 WTF on June 11, 2006, 04:12:36 PM
but i could keep the results a secret and sell them to people wanting to know, lol
Title: How about dump valves
Post by: Grizzly on June 11, 2006, 06:22:53 PM
I can\'t see there being a power diffrence? i think it just helps the Responce of the turbo, basicly the turbo is spinning alot slower when you open the throttle again after a gear change, But!! when the Turbo is spooled up having a BOV will make no diffrence at all to the amount of air the Turbo is pushing out.

I have driven a Single turbo with no BOV and tbh there was not alot of diffrence. But you hear of people having problems with the Turbo\'s Shaft snapping on cheap Turbo\'s due to the extra loads.