dump valve

[colinrx7surrey]

hi i own a mazda rx7 2nd gen could anyone help me out! i want to change the standard bosch dump valve to an upgraded one!
does any one have any ideas,plus ,where to get one,and how much it  would cost ,and how easy it is to fit!!cheers colin

[grinder]

i think there is a cue forming for a nice shiney dump valve - but im not paying the 120+ that people want for a new one

[Brett]

I\'m tempted to make my own tbh.  Just a question of finding a spring that will do the job.

[grinder]

didnt think it would be that simple

you could make a killing though if you could

does the valve have to be rx7 specific - or can you use any - im not really clued up on these things

so if some ( cough brett ) could explain what you need ( ie pipe work and the such like ) - it would be a huge benefit !

[colinrx7surrey]

surley there must be some company some where that makes a dv upgrade for a 2nd gen r7!!!anyone doing any research lol

[grinder]

i think pip @ WGT can get them for about £85 or something like that

could be worth a call to him ?

[colinrx7surrey]

anymore details on that 1,like a web address or contact number cheers grinder....colin

[grinder]

errrrrrr  ....

runs off to check favourites ...

http://www.wgtautodevelopments.co.uk/rx7.htm

[Brett]

Technically its a very simple device.  Its simply a one way valve placed in line with the high pressure side of the induction system.  When the pressure reaches a set point it overcomes the force of the valve spring, this opens up a vent to the atmosphere where the stored pressure can escape instead of back pressurising the intake route to the pooint of stalling the compressor.  :cool

 All I need to do is find out the maximum psi I want in the High pressure side of the intake system, find a suitable place to fit the BOV (turbo to intercooler hose sounds like a good place), get hold of a suitable poundage spring, turn and mill a suitable diameter body, polish it up and fit it to the car.

 Its almost too easy....

[colinrx7surrey]

sounds good brett if u  come up with one let me know cheers colin

[Thud]

I\'ve never been too sure about BOVs in rotaries. The stock valve vents back into the air intake system and BOVs vent to the atmosphere.

This means that with a BOV the fluel mixture to your engine becomes temporary rich when it vents. Not sure if this is a problem our not but it\'s always made me shy away from them.

[Brett]

True, but I\'m talking about fitting a BOV that will only operate at pressures that I consider iffy, not sure what those are going to be yet, I\'ll have to do some more research.  I may have to wire up a n/o switch on one side of the BOV which is closed when the BOV operates, that will give me an input signal I can use if fueling during the BO cycle becomes an issue.

[rx7veilside]

vent to atmo valves will not cause a problem on a rotary as u are not running a maf sensor..on cars with maf air is metered as it enters and on lift off the measurement is altered so the maf immdlty injects more fuel screwing up the mixture...any dump valve will work on a rx7 just depends on how ur car is plumbed in ie twins or single aftermarket intercooler or standard

[Brett]

STandard single turbo on the FC.  

 Anybody know what the upper safe limits are, in regard to what bhp you can run with the stock turbo?

[travellinbob]

The bloke who built a few engines for me whilst I was in oZ designed and built his own blow off valve. I think he only ever made 2 of them and they worked reasonably well. I dont think he fully developed them as most of his customers wanted to supply known brabd names. And plus as we all know development takes alot of time. Something of which he never had too much of!
 Hi sname is Kevin webb and his buisness is South coast Rotaries.