Mazda Rotary Club

General => General Technical => Topic started by: GaseJo on April 13, 2009, 03:07:32 PM

Title: A few queries
Post by: GaseJo on April 13, 2009, 03:07:32 PM
Hi,

I have just finished doing a few bits & pieces on my 94 Rex so now she is ready for a mapping session.  It has been over 2 years since i first got the car & in that time i have only driven it to & from MOT & respray. So i have just taken her out for a spin to see if there is any problems which could effect the mapping session.

1st. When the first turbo spools up it sounds more like a party blower than a whistle

The boost gauge goes to just under 1 & on the commander reads 0.72 & holds there does not seem to lose boost so is this the normal sound of a rex spooling up?

2nd the second turbo seem to kick in at about 6000 & when it comes on it pins me into the seat alot more than when the first kicks in

does this sound about right or should it kick in earlier in the rev range?


Thanks for any info Garith..
Title: A few queries
Post by: lee mills on April 13, 2009, 03:26:32 PM
the second turbo should kick in around 4500 iirc
Title: A few queries
Post by: GaseJo on April 13, 2009, 03:54:23 PM
Thanks Lee

seems to be kicking in late then.. Anyone any ideas why this would happen??
Title: A few queries
Post by: neil_jdmr on April 13, 2009, 05:55:38 PM
Standard boost on fd\'s is 0.68 bar so your commander is reading correct and depending on condition there is always a bit of fluctuation so 0.72 is perfectly normal.
 
Your boost pattern in bar will go as such 0.7  -  0.5  -  0.7 with the 0.5 being the transition from first to second turbo.
 
When the second turbo comes on at 4500rpm you should feel a definate increase in power. Both the first and second boost to the same 0.7bar boost pressure but the surge from the second is due to it being a larger turbine on the second unit.
 
If the second is coming on late its likely a solenoid/check valve issue, try reading up on the robinette site through the troubleshooting section