MR2 supercharger in a TS

[Biba]

Hopefully I won't get immediately banned, but I'm trying to get information on the MR2 supercharger which I believe is referred to as the 4-AGZE (?).

The TS in the title refers to an Alfa Romeo twin spark engine (2000cc, dohc, 4-cylinder inline).

I have some pretty basic questions such as would a clutch from an A/C compressor be strong enough? I need to use a V-belt/pulley. And could the s/c work as a stand alone unit, meaning could I set it up with an on/off switch to kick in and then activate the bypass items to close, then bypass when off with the pulley freewheeling?

Any info would be much appreciated.

Biba

[MR2Jedi]

The 4agze is one of the engines for the 1st gen MR2.
I own a 2nd gen, so I'm only lightly familiar with the 4agze, but I think the SC is clutched stock.
We have a couple guys here who know the 1st gens very well. I'm sure they'll chime in soon.
Welcome to the forum.

[Biba]

MR2Jedi, thanks for replying. I wasn't sure if the 4-AGZE referred to the engine, the s/c, or both.

Yes, s/c has a clutch, but it appears to be inside the serpentine belt pulley - which won't work for me. I need to use a V-pulley/belt arrangement.

I'm not especially trying to know about the early ones, but was told that a MR2 s/c might work for what I'm trying to do. Obviously the less complicated the better.

Biba

[mr2tim]

4A-GZE Supercharger (SC-12) 1988-89 Mark 1 Mr2- 8PSI

Hi Bee

I'm a 21 year owner of a SC racecar/DD so here goes.

The modification of the output shaft to convert to the Vee pulley setup would be a test of your (or your machinist's) ingenuity. The OEM unit uses a K-5 belt and is NOT a serpentine as there is another belt that powers the AC.

I'd consider re-configuring the K-5 pulley on the existing OEM unit. The K-5 could be cut off and the vee added without sacrificing the entire electomagnetic clutch pulley.

As with all electo-magnetic clutches this one could put on and off with any electrical switch, push-button, toggle etc..

This unit does come equipped with a ECU operated ABV (or automatic blow-off valve) which limits the total boost output soas not to overboost between boosts/shifts. This can be done away with out serious engine damage, and is done occasionally by hot rodders of this GZE engine.

Optional aftermarket pulleys for the SC-12 unit will produce 10PSI (TRD) and 14PSI

You might be advised that there is a 2nd generation of this design, an SC-14, which is available on the JDM 4A-GZE and the 2.4L Sc Previa Van which produces 12PSI but mounting hardware is slightly different.

If you drop me YOUR email as a PM I'd be glad to forward pictures of the individual parts and further discuss your engineering options and ideas.

mr2tim
Construction Technologist BGSU
SupercharZed ToyZ RacZing

***************************
89 SC Race Prepared/Street Licensed
88 SC Street car
87 NA Hardtop Drag Car
87 NA Street Car Sunroof
86 AT NA Parts car
87 V6 Fiero Race Car
95 Camaro Z-28 Race/Street
83 Celica Autocross Prepped
70 Chevy Nova 396/325HP-Drag
64 Olds F-85 Drag Car

[Biba]

mr2tim, I'm very impressed by your credentials and thanks for replying. I must admit I'm a bit up in the air as whether adding a s/c is a good idea or not. I'll add that I want it as simple and bullet-proof as possible without any low speed fussiness from the mod - which definitely includes keeping the engine temp. under control even on a 100 degree So.Cal. day. I'll add here that A/C is more important to me than having a s/c and even it (on my current, non-twin spark engine) is a problem.

Addressing the heat problem, a fellow in Tasmania has built a twin-charge 4-cylinder for his Alfetta GT and he's just installed a considerably more efficient custom radiator - so that most likely would be something I need to do from the start.

Budget is also a major consideration, and my plan is to be able to complete the modification with rebuilding the TS and replacing the pistons with custom 8 or 8.5:1 one's, aftermarket chip for the Motronic, and radiator being the major costs involved.

I'll say upfront that I'm an older guy, that this is my one and only daily driver, and that I'm simply looking for a smooth running engine (which includes idle) with more power on tap when wanted. No plan on racing the car.

A weak point of my GT is that since it has a transaxle, there are three rubber donuts on the driveshaft and their life span will obviously be reduced with the increased hp. This is one reason I want to be able to not have the s/c activated - but the engine still running well at speed.

Regarding the latter, I understand that the bypass on the MR2 s/c's is very small. I assume this is because the bypass normally would only be used at idle. Is there a work-around for this without getting into a major plumbing situation?

The pulley is also a major concern of mine. There is a crank pulley available which has a toothed pulley but it is only 54 mm (2.12") in diameter. I just goggled 'Toyota supercharger MK-5 belt' and your reply to me is the first - and only one that applied of those which came up. So what is a MK-5 pulley/belt? And what is the diameter of the crank pulley on the MR2?

Recently there have been two Previa s/c's on eBay for not much money. One for a $100, but with $100 for shipping (from a place about 40 miles from me).

Tell me what to expect from adding a s/c and let's assume I can get it set up with an on/off switch. Let's say I'm entering a freeway with lots of traffic, going about 30 mph and hit the on button. What will happen with 8psi, and what will happen with 12 psi? Sure, very relative, I know, but please give me some idea.

Biba

[ToyotaTechGeek]

sorry not trying to bust your balls, Tim, but what 4AGZ-E came with a SC14? NONE: not even JDM. Previa, yes; 1GGGZ-E, yes. 4AGZ-E, not so much.

please don't be mistaken as TRD never made a pulley and advertised PSI is variable and is different in every situation. some see higher PSI due to things like heatsoak, so...

an SC14 conversion takes a bit of fabrication skills. custom bracketry and charge piping are necessary. then again this is a custom application, so fabrication is the word of the day.

i don't know that adding a SC for the occasional on-ramp is worth the time and effort. afterall, with all of that work why wouldn't you want it on all the time? i think you'll find that along with some extra heat, fuel enrichment would need to be addressed. also, spark control. those are your criteria for any boosted application. yes, the oem ABV is tiny. does it harm driveability in any way? i don't think so, but then again i addressed this in my own vehicle.

[mr2tim]

The pulley was HKS not TRD.

I never had JDM SC in hand but was given pictures indicating the JDM SC appeared different than our domestic one, I assumed if it was different it was not a Sc-12? Apparently it just moujnts differently huh?

Originally Posted by ToyotaTechGeek

sorry not trying to bust your balls, Tim, but what 4AGZ-E came with a SC14? NONE: not even JDM. Previa, yes; 1GGGZ-E, yes. 4AGZ-E, not so much.

please don't be mistaken as TRD never made a pulley and advertised PSI is variable and is different in every situation. some see higher PSI due to things like heatsoak, so...

an SC14 conversion takes a bit of fabrication skills. custom bracketry and charge piping are necessary. then again this is a custom application, so fabrication is the word of the day.

i don't know that adding a SC for the occasional on-ramp is worth the time and effort. afterall, with all of that work why wouldn't you want it on all the time? i think you'll find that along with some extra heat, fuel enrichment would need to be addressed. also, spark control. those are your criteria for any boosted application. yes, the oem ABV is tiny. does it harm driveability in any way? i don't think so, but then again i addressed this in my own vehicle.

[ToyotaTechGeek]

Originally Posted by mr2tim

The pulley was HKS not TRD.

I never had JDM SC in hand but was given pictures indicating the JDM SC appeared different than our domestic one, I assumed if it was different it was not a Sc-12? Apparently it just moujnts differently huh?

the JDM SC is still an SC12, but with a smaller SC pulley: not a larger aftermarket crank pulley.