aah.. being unemployed there is just too much time over to think about the car :)
Has anyone relocated the dump valve? IMHO it is in a pretty crapy place right now. Dumping hot air right after the turbo back into the inlet pipe just doesn't seem like a good idea. Maybe not by much, but wouldn't this cause heatsoaking to the intercooler which has been discused here before? Most turbo cars have the dump valve after the IC, and "by the book" it should be pretty close to the throttle body. Anyone tried it? What do you think? I am concidering it, but before I do, I want to see what the Jabbasport kit includes :)
Carl
max_torque
05-01-2003, 23:03
Once again it's swings and roundabouts with dump valve location:
close to the turbo is best for maximising compressor rpm on a gear change, because there will be less wall friction from moving air through intercooler etc and then back to compressor, but as you say the air will be hotter, however as the compressor is doing no work at this point the air temp will not rise again as it passes through the compressor. The biggest problem with post compressor return, rather than post intercooler is in the transient filling time of the intercooler and piping, which if you've got a big boost car will actually see a reversal of air flow direction when the dv opens and the throttle shuts. It takes time to both reverse the airflow, and refil the ic and system back to full boost pressure. If this is a bigger negative effect than loosing some compressor speed depends upon the system it's installed in. with a large capacity FMIC and pipe work it can be better to have the DV post IC. The other big problem with Internal DV's is the reverse flow through the MAF meter. typically on a ME7 ems system we would resort to a calculated airflow value during extreme throttle tip-outs as the MAF signal is unreliable. Changeing the DV position may screw up the FMEM MAF calibration and cause some funny drivability issues on big tip-outs.
Also remember while all that hot air goes round in circles in the compressor the static air in the ic will have longer to cool, and you'll get a nice blast of cold air next time you open the throttle, although actually this doesn't really happen because, a) it all happens too quickly for serious IC heat transfer to occur, b) the plenum is practically at a vacuum so there is no heat transfer from it's walls.
The simple answer is - try it!