Toyota MR2 Message Board - View Single Post - 4A-GZE MK1 Engine Supercharger questions

englishmike · 10-28-2009, 10:47 AM

I have not yet checked to see if the switched is hooked up to anything. It doesnt seem to change anything.

I was reading the 1987 car and driver review and it states

"If you're cuising along with the supercharger disengaged, a little pressure on the accelerator will summon full boost in just a fraction of a second. The supercharger makes the little motor feel much bigger than it is, from the liftoff right up to the 7500 rpm redline. Compared with the normally asporated engine, the blown motor has only one drawback (besides higher fuel consumption, of course); a groan from the supercharger at any speed beyond 4000 rpm. The melody just isn't as sweet."

From this text it seems the supercharged engages as soon as you press down on the gas pedal and then disengages when you take your foot off.

I was under the impression the supercharger only comes on over 4000rpm AND when the gas pedal is pressed.

It also says"Boost level is set at 8 PSI and achieved at 4000 RPM and higher, however the supercharger creates usable boost from idle through redline."

Does this mean max boost comes on at 4k rpm? Does this mean the supercharger runs from idle and comes on whenever the accelerator is pressed? If so then why is the sc light needed on the dash to tell me the supercharger is running?

I then read an article in grassroots motorsports 1988 "the supercharger is disengaged at cruising speeds by an electromagnetic clutch and air bypass system" This seems to contradict the above information.

Can someone explain this in simple terms.

With regards to the air bypass valve being blocked on my mr2, does this mean the car will use more fuel because boost is being sent? Why did Toyota fit the ABV in the first place? If its to prevent overboosting, should I unblock it? Is it dangerous for the engine?

10-28-2009, 10:47 AM	#10 (permalink)
englishmike Some Skills Join Date: Sep 2009 Location: Birmingham, Alabama Posts: 85 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	I have not yet checked to see if the switched is hooked up to anything. It doesnt seem to change anything. I was reading the 1987 car and driver review and it states "If you're cuising along with the supercharger disengaged, a little pressure on the accelerator will summon full boost in just a fraction of a second. The supercharger makes the little motor feel much bigger than it is, from the liftoff right up to the 7500 rpm redline. Compared with the normally asporated engine, the blown motor has only one drawback (besides higher fuel consumption, of course); a groan from the supercharger at any speed beyond 4000 rpm. The melody just isn't as sweet." From this text it seems the supercharged engages as soon as you press down on the gas pedal and then disengages when you take your foot off. I was under the impression the supercharger only comes on over 4000rpm AND when the gas pedal is pressed. It also says"Boost level is set at 8 PSI and achieved at 4000 RPM and higher, however the supercharger creates usable boost from idle through redline." Does this mean max boost comes on at 4k rpm? Does this mean the supercharger runs from idle and comes on whenever the accelerator is pressed? If so then why is the sc light needed on the dash to tell me the supercharger is running? I then read an article in grassroots motorsports 1988 "the supercharger is disengaged at cruising speeds by an electromagnetic clutch and air bypass system" This seems to contradict the above information. Can someone explain this in simple terms. With regards to the air bypass valve being blocked on my mr2, does this mean the car will use more fuel because boost is being sent? Why did Toyota fit the ABV in the first place? If its to prevent overboosting, should I unblock it? Is it dangerous for the engine?