Just had an oversized pulley fitted to my SC...

[munter]

Just back from holiday and picked up my car from Woodsport on the way back. Among a few nice little bits and pieces Paul fitted my Fensport oversized pulley and did the ABV mod with blanking plate.

All I can say is wow! A serious performance boost, both in acceleration and torque. Driving back up the A1m the improvement in torque at motorway speeds is very notable especially when overtaking with overdrive engaged. Off the mark acceleration is phenomenal now as well.

Best thing of all? It sounds much nicer. Great rasp from the engine now and the SC unit whir is far more noticeable over the booming exhaust note!

One strange thing is that at certain revs you get a slight fluttering sound - any ideas? Could this be due to there being no harmonic dampner on the Fensport pulley? I do remember reading something about this ages ago.

Paul had mentioned that he hadn't done much work on superchargers and was a little concerned at max boost the engine would run lean. He'd been looking at the grunt boxes which seem to be used a lot in the US but his research seemed to indicate they didn't work with JDM cars and that they weren't needed. Obviously I want to make sure of this and I know many of you have had experience of running the higher boost pulleys on your cars, have you had any problems? Anyone used a grunt box or alternatively have had lean running issues?

Thanks - now off to take it out for a play again!!

Cheers
P

[greglebon]

All MK1 S/c's will run out of puff using the oversize pulley's mainly due to the charge temp being super hot.
This leads to detonation, detected by the knock sensor, which in turn retards the timing.
The ECU also switchs the injectors to 100% duty (basically full on!) to get as much fuel into the cylinders, and acting to cool the charge.
This results in a loss of power and RICH running....

However...IF your fuel pressure is low at high revs, then the engine will run lean and you'll probably blow the HG or worse within a short time, if you're wellying it everywhere...!

The SC 4AGZE engines have a lower power peak than the NA 4AGE (5500rpm S/C compared to 6600 N/A, iirc?), so revving over this will basically not get you any more performance.....
To utilise the extra boost, you need mod the mapping, either using a standalone EMS or a piggyback.
Either way, you need to change settings.....

To run a DECENT oversize pulley setup you NEED to do the following:
1) improve your intercooling 100%, either a larger IC in a DECENT airflow, or a W2A chargecooler setup.
2) make sure you have a rising-rate FPR fitted AND (crucially) that it has been set up on a rolling road.

If you feel "experimental", get hold of a dash mounted fuel pressure gauge.
Try to get an electric one with a sensor rather than one which has the fuel line running into the cabin!

Then watch what happens to fuel pressure at high revs: it should remain at least over 37psi right to the redline (well...5500rpm).

If its less than this, you're gonna have problems...
You could fit an inline fuel pump , or simply upgrade the stock one
This may have been done already, but it pays to be aware......

Been there...done that!

[jon_st205]

The 1st generation 4AGZE doesn't have a knock sensor.

TBH you'll be fine, just make sure car is running well, intercooler is nice and clean inside, and take it easy if ambient temps get very high. Otherwise, enjoy

[ulysess1966]

I've got a SC with a big pulley getting about 11 PSI and I've been investigating building a grunt-style box based on some reverse engineering because the car definitely peaks out just above 5000 RPM. I hooked up a digital voltmeter to the O2 sensor connection on the diagnostic connector and ran that up to the dash to try this out and got a definite lean condition above 5000 RPM, at least based on the fuel/air mixture, as the voltage dropped suddenly to under 0.3V. I'm no expert on these things so you'd need to verify this yourself.

I tried a matched pair of Apexi boxes (S-AFC and S-ITC), but found them hard to set up and took them out again because I didn't know if they could really out-trick the ECU enough to fix the problem.

The Grunt Box triggers the cold start injector when the throttle is near full open (this can be adjusted) and the revs are under a certain point (2000 RPM or something I think). It is a bit of a blunt instrument, but solves some of the fuelling issues. I've built a prototype using a microcontroller (tiny computer) that has a bit more intelligence and can trigger extra fuelling based on several parameters and also adjust the amount of additional fuelling (I think the Grunt Box can only turn the CSI on and off, but if I'm wrong someone let me know) with 4 different fuel levels (quarter, half, 3-quarter and full).

I have a lot more work to do on this, but I'm hoping to make some headway before the end of this summer.

[JMR_AW11]

The SC ECU was one of the ECUs I reverse engineered many years ago. I looked at both the USDM ECU and several of the JDM variants and they all have a curious map in them that prevents the ECU from calculating the air mass above a limit set in a 'limit' vs rpm map in the ROM code. This map switches in with the SC operation.

It basically reduces the limit in a gradual curve from about 4000rpm downwards (from memory) and so the leanoff effect gets worse with reducing rpm.

It also affects the ignition timing as it prevents the ECU from navigating to parts of its 3D ignition map. So it is more than a leanout problem and the gruntbox is a crude solution in this respect as it can't alter the timing to where it is optimal.

I did make a quick and dirty mod board that allowed the JDM SC ECU ROM code to be altered/remapped but it never ever got tested in a real car. It worked fine on a test jig.

I have no idea where it is now, probably in bits in the loft or I may have binned it as I chucked a lot of 3SGTE stuff away a few years ago and probably binned the SC ECUs as well.

But both JDM and USDM ECUs have the limiter map so I would expect them to be very similar. However, I suspect that you have to seriously clog the car at lowish revs to really see this so maybe UK owners are more smooth/sympathetic than US owners in the way they drive the car at lower rpms with the bigger pulley?

[Zirax]

I have recently got an SC with an oversized pulley already fitted.

My thoughts are to get one of Woodsports TRD engine lids & fit a fan onto the IC. It may require a little bit of welding on the lid to make the webbing work.

The general temperature of the engine bay is pretty high with the restrictions of the airflow (to force it through the intercooler). The idea is to have some of the heat pass out one side, and a fan to pull air through the IC.

[Charged]

The pulley mod is fantastic, it gives the Mk1 the power and the noise it should have had in the first place.

[greglebon]

The 1st generation 4AGZE doesn't have a knock sensor.

Wasn't aware of that, tbh: just assumed it to be a no-brainer for Toyota...!?

Yeh, the upper end was where the problems are: for general driving / overtaking, etc, it was great!

By the time you're in 5th gear and up to 5k, you're basically going silly-fast anyway.......?

iirc, most people seemed to say that they only saw real-world problems on track, on long straights, etc......?

From 1500rpm up to 4500prm it was much better than my Mk3 V6, and sounded better too.....!

(In fact, WHY did I ever get rid of my Mk1 AE101 "NightHawk"...!?!??! )

[PW@Woodsport]

From 1500rpm up to 4500prm it was much better than my Mk3 V6, and sounded better too.....!

Balls lol

[Lauren]

I have recently got an SC with an oversized pulley already fitted.

My thoughts are to get one of Woodsports TRD engine lids & fit a fan onto the IC. It may require a little bit of welding on the lid to make the webbing work.

The general temperature of the engine bay is pretty high with the restrictions of the airflow (to force it through the intercooler). The idea is to have some of the heat pass out one side, and a fan to pull air through the IC.

Seriously, I wouldn't bother with a fan unless you need the IC to be cooled when the car is standing still. When the car is moving it will be more of a hinderance to air flow tbh.

The best way to efficient intercooling would be to either move the intercooler out of the engine bay or do it MK2 style ie, behind the vent. Or seal it off from the engine bay.

I did this back in 2003, it was very effective:



Also the ABV needs to be removed completely.

[kaiowas]

The 1st generation 4AGZE doesn't have a knock sensor.

Not sure what you mean by "1st generation" but I've had about 5 GZE engines in various states pass through my hands and every one had a knock sensor fitted.

[jon_st205]

In retrospect I think you're right.

[JMR_AW11]

Yes, I had several variants of the SC ECU here and they all had knock sensor MCU chips inside. These were JDM and USDM AFM based ECUs.

[T.F.S.]

I didn't realise the MK1 guys needed WI so badly...800cc of methanol with a 10% water content would make a massive difference on the cars mentioned in this thread.

Lower temps by 30c, increase octane, add fuel...

[Lauren]

Tbh an oversized pulley is fine on the road. The intercooler will heat soak eventually but it will not be an issue on the road.

If you're going on track and I'm sure Paul won't be then it becomes more of an issue.

Water injection works but really is a 'band aid' for inefficient intercooling. Better to get the intercooling sorted if that is the problem.

[T.F.S.]

Tbh an oversized pulley is fine on the road. The intercooler will heat soak eventually but it will not be an issue on the road.

If you're going on track and I'm sure Paul won't be then it becomes more of an issue.

Water injection works but really is a 'band aid' for inefficient intercooling. Better to get the intercooling sorted if that is the problem.

I dont see it like that...I dont even have an intercooler or chargecooler fitted to the cat at all and my inlet temps are lower than most people who have boot mounts.

There is also no such thing as an intercooler that reduces knock and increases octane.

[greglebon]

From 1500rpm up to 4500prm it was much better than my Mk3 V6, and sounded better too.....!

Balls lol

Oh..I dunno, Paul...!

The SC whine was quite addictive......?

Now the 1MZ with a Roots: THAT would be a sound to behold....!

I think I have "Missing-my-Mk1-itis"...?

[greglebon]

WI can replace an IC...but it MUST be set up correctly..!

WI with Methanol 50/50 taeks a LOT of heat energy from th charge, but the misting must be correct, and that means regulating the pump pressure and introducing the optimal amount of liquid into the charge at any given time.

You can't just fit an Aquamist, 0.7 jet and a switch and expect optimal power returns..!

Too much water just robs power...sure, you wont get any detonation, but you'll not get any power increase, either!

Another "hybrid" way to improve things is to use a WI setup squirting a mist onto your IC: if you do this when stationary / slow moving, you can eliminate heatsoak entirely.

You can also experiment with WI fitted PRE-SC.

As the Roots' Achilles heel is the fact that it recycles hot pressurised air back to its inlet, pre-cooling the charge can help massively here.

I reckon that if you fitted a well-calibrated (map-controlled, basically) 2 stage WI setup (pre-SC and pre-cylinder), you could get some really good figures from the SC12...possibly 200hp+..?

All down to minimising the in-efficiencies of the Roots, and eliminating any pressure drop / heatsoak from the p1$$-poor top-mount IC fitted to the MR2 SC...!?

Lauren's setup works too...cheaper and easier than the above....

Basically you just need to sort the intercooling out a little, and adjust your driving style for a slightly lower 5.5k power band...

Job done!

[T.F.S.]

All you actually need is a progressive kit and a nozzle or two, it's not very hard to complete and is a lot easier than fitting a big laggy boot mount intercooler.

But I know that because I have done it.





All that is needed with the car mentioned i the first post is an injector after the intercooler...temps drop by 30c, engine has more power and far less prone to failure.

[greglebon]

I've done it too........


What you say to do WILL offer a marked improvement over nothing...

.......But I KNOW it could be a lot better if you put the work in......