No Bov, And Turbo Life-span

[Gazee]

See what user "the Maffia" has to say about GT30, stock bov and 300rwkw.

is that a modified stock bov?

or a stock bov with the little hole at the bottom as it was from factory?

[TTT]

i'm pretty sure it's as stock as the day it left the Mitsubishi factory.

send him a PM and ask him..

He won't hurt you..

he's not REALLY the Mafia...

*horses head not included in his reply*

[discopotato03]

Me too , I've got 2c to spend .

Lets just say you have your engine running on boost and for whatever reason you leap off the go pedal . Inlet manifold and exhaust flow drops like a brick and for a very short time the turbos innertia will prevent it from stopping dead . What you now have is an area of higher pressure between the compressor outlet and the throttle plate/s and nowhere for the compressed volume to vent other than back towards the compressor . Rotary compressors are designed to be efficient in one airflow direction so they react badly when you get the reversal happening . Cavitation/hissys call it what you like but the compressor is definately in not happy Jan mode .

Like some others I got to see the the technology change (84-96 era) going from a std engined Skyline DR30RS (FJ20ET) to a similar state R33 GTS25T . Like the RB30ET the FJ had no throttle closed recirculation valve (I'll call it TCRV) and it did make the flutter noise even with its std boost pressure of ~ 7 PSI . The thing I really did notice was the DR30 felt a little strange going from a loaded state ie 1/2 throttle to ALMOST closed , the residual pressure in the system gave a sort of delay to the engine unloading or backing off - unless the throttle was closed . The R33 does none of this and is quite responsive to rapid on/off throttle inputs . Now the load sensing devise is different in these cars the older being gate type AFM and the later Hotwire MAF . Unlike a MAP sensor these both react to mass air flow so are obviously upstream devices . If anything the MAP sensor is the one kept mostly in the dark because it can't see whats happening on the outside of the throttle plates so pressure out here means nothing to it .

When you have a TCRV it becomes the "compressed volumes" escape route but I'd say its critical how its fed back into the system upstream of the compressor housing . A MAF sensor can only react to airflow throught it - so if it gets a sudden pressure rise on the engine side flow through it could slow or even pause . No airflow means no load signal so the ECU probably thinks fuel off and siesta time . I think it would pay to look at how Nissan set out their TCRV systems so that you can copy the positive aspects and avoid the stalling or fuel off antics .

I think the bottom line is later RB powered cars use them so until they create a problem leave it as it is . Even the std one does the hiss thing with non std filters ie pods fitted . If I was going to do anything to mine I'd fit the twinned RB26 ones and call it a day , I believe it comes back to the airflow for power instead of boost for power because extra pressure brings extra dramas IMO .

Almost forgot , later era cars are using higher boost pressure than FJ20ET/RB30ET cars did so the TCRV would have more potential to correct drivability glitches with rapid throttle inputs .

2c gone cheers A .

[TTT]

should have kept the DR30 disco..

http://www.powerplayimports.com/repository..._DR30-Front.jpg

teh sexy

[discopotato03]

Nope no regrets . In a car of that weight strut front/semi trailing arm IRS and can't steer straight link steering is a real downer . Just about every aspect of R30's paints you into a corner and FJ20's are very crude electrically speaking . You learn to hate two twin row timing chains and the dizzy type CAS . We won't go into 4 stud hubs and disks that bolt behind them will we ...

I didn't like to hear it at the time but someone here made it clear that the overall technology jump from R30/31 to R32 and later was "a quantam leap" . Very good advice .