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

[T.F.S.]

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......

Do you have the logs that I can have a look at and compare to mine? Didn't realise there was someone else on the board that removed the intercooler/chargecooler and uses WM alone.

What injected amount did you end up with and what % of methanol, what was the temp difference on boost?

[greglebon]

I have a load of scribbled stuff somewhere....

I only really got 30% into the research, but enough to be sure there's a LOT of mileage with a WI-only setup.....

Off the top of my head, I ended up with a 0.7mm nozzle pre-cylinder, a 0.5mm pre-S/C. I started with 30% Methanol, but went to pure water soon after.
I figured that I would wait until I had the control side perfected before introducing Methanol to the equation..? That way, I would have got some good figures with water, and would be able to gauge the improvement with Methanol more accurately..?

I played around with the water pressure to adjust flow rate. Plan was to use a Megasquirt 2 (I was into them at the time!) to control the WI totally, with a map, based on boost pressure, charge temp, ambient temp and throttle position.

Even in the early days, I saw a virtually instant 40C drop in charge temp.
When I started experimenting more, I was getting around 55C drop on average.
Bear in mind, though, that my SC12 on full boost was forcing temps up to 110C with no I/C: thats enough to shag any engine fairly rapidly.....

The well-known "drop off" of power at high revs vanished instantly with WI: I put this down to the fact that the ECU never detected any knock, and thus did not switch in the "safety mode" (100% fuel, timing cut, etc)..?

Car was a different beast with no IC.....instant response, fantastic sound, etc....

I WISH someone would see this through properly, as there is loads of potential, ESPECIALLY with the 4AGZE in an MR2....
If there was an application for a WI-only solution, that is it!

I don't have time anymore, and the MS community were not very "accomodating" when it came to my plans for UK market domination 4 years ago.....!

Of course, the ultimate solution is to ditch the SC12 and fit a twin-screw SC.....

[coanda]

This sounds very interesting - and the advantages are very appealing to me.

How fast do you get through water? a litre every 50 miles or something?

[elbon50]

Would water injection be any advantage with an N/A engine ?

[T.F.S.]

This sounds very interesting - and the advantages are very appealing to me.

How fast do you get through water? a litre every 50 miles or something?

Depends how often you go full throttle.

Injecting 250cc with a 2 liter tank gives you about 10 mins of full throttle time and you rarely use more than a few seconds at a time in a fast car.

An N/A car will not really gain any advantage from injecting water but they do get gains with methanol

Kits are available in the traders section from myself and if you want to know more technical stuff just have a look at my build thread.

[greglebon]

Interestingly.....yes, an NA car DOES benefit from WI......

If you drive your NA car at 5am on a summers day, and then at 2pm, the car will feel much more responsive in the morning, so injecting a very fine mist into the airstream on a hot summers day will show some noticeable improvement....

This is due to the amazing ability of water to absorb energy at the point of evaporation, yet show no raise in temperature.
It takes a lot of energy to evaporate water, and this energy comes from the heat in the charge...Net result? Some steam and a noticeably cooler charge......

It could be argued that in an NA application, the steam is displacing a very tiny amount of air volume, but in practice it is not as B+W as this.

If you think about it, our early morning air is only cooler because it contains millions of very tiny water droplets...WI emulates this at midday!

Add Methanol, the effect is accelerated.....

The smaller the droplets, the better the effect, so you need a tiny nozzle / high pressure pump (or both).
If the drops are too big, then you're basically just heating water, which DOES displace air and give no benefit.
What you need is for the atomised water to evaporate on contact with the charge, absorbing heat energy.

So you need to vary the amount / droplet size according to the charge temp: this requires some form of control.....

But, if you just want to prevent detonation at high boost, then you can have an on/off system, but it still ideally needs some form of setting up.....

[T.F.S.]

Yea that is all that but in the real world when a customer spends near £200 on a kit they want more than a 1bhp difference on a dyno and in this country they wont really see it, if we lived in Arizona things might be different.

With methanol injection that starts to change though, you do see gains on the dyno with N/A.

[greglebon]

You dont need a dyno to feel the difference........and thats in Sussex, UK...!

Dyno's...

£200..!? That'll barely buy the pump, nozzles and tank...!?

[T.F.S.]

You dont need a dyno to feel the difference........and thats in Sussex, UK...!

Dyno's...

Yea people use dynos to see exactly where the gains are made mate, they work far better than your placebo effect runs.

[greglebon]

True...but anyone putting their N/A on the rollers after fitting WI is a tool anyway, lets face it...!?

I dont reckon that ANY dyno could accurately measure <1hp anyway....?

Most are accurate give or take 20%, after transmission losses, etc.....
McLaren or Ricardo, etc, may be able to measure 1hp on a static system, but any garage-based setup...forget it...!

Having seen your YouTube vid, are you using the Link to control the WI..?
If not, why not!?

[T.F.S.]

True...but anyone putting their N/A on the rollers after fitting WI is a tool anyway, lets face it...!?

I dont reckon that ANY dyno could accurately measure <1hp anyway....?

Most are accurate give or take 20%, after transmission losses, etc.....
McLaren or Ricardo, etc, may be able to measure 1hp on a static system, but any garage-based setup...forget it...!

Having seen your YouTube vid, are you using the Link to control the WI..?
If not, why not!?

I just wouldnt like to sell something to someone if they expected "good" results only to find nothing has changed on the next RR day they have with their clubs...bad press for WI. (and bad press for me)

The link G4 cant really control the solenoid/pump the way I would like it to so I am using a rather nifty progressive controller from coolingmist..this does make tuning the ECU harder though as my mapper keeps complaining lol.

[munter]

Thanks for all the replies folks. Given the car is an auto I doubt I'll ever be doing trackdays in it so I'm not too worried about going crazy on water cooling etc. Also because I'm in Scotland where the ambient temperature is rarely in double figures (well nearly) I don't think I'll have too many problems in day to day driving.

I might look at improving air flow through the IC but I think that should suffice. Based on the comments before it doesn't seem there is any easily available electronics that will be suitable either and I'm not keen to run experiements on my car until I know what I'm doing with the basics!

Since getting the mods done I have noticed a belt slip when at full boost so will need to get that tightened up. Also when at idle there is a noticable high pitched rubbing sound from the supercharger pulley area (not the cam pulley) which sounds like the pulley needs oiled. It's quite loud and noticeable. Anyone else had this after fitting the larger pulley? Just sounds like it isnt smooth... sure its not a big deal but want to check.

Cheers
P

[Fab4MR2]

A few points regarding the initial discussion that I have learned over the years:

The usdm and jdm ecu's for the AW11 4agze do have different mapping, as pointed out earlier. The USDM having a far greater number of map points probably due to smog control related issues.

A large 175mm crank pulley causes the usdm ecu much more of a problem than the jdm ecu, for reasons not fully diagnosed as yet. Smaller crank pulleys cause less of an issue, with the HKS (157mm) or Blitz (160mm) ones causing little if any.

A large crank pulley on a 1st gen. usdm 4agze causes a lean-out issue between 3.5-4k rpm only. The Grunt Box was built to overcome that by utilizing the CSI during that part of the rpm scale, and it works very well since it is a limited rpm issue. There is no need for it to also adjust timing, and dyno plots have shown that it reliably creates very smooth torque/hp curves.

Large crank pulleys on 1st gen. usdm 4agze's create a relatively rich upper rpm reading, but not usually so much that it is a major concern. Torque, and hp readings continue upwards quite smoothly with the large crank pulleys, and only roll-off due to the stock cams, which is to be expected. Aftermarket cams, if used properly, provide expected rises in upper hp, and can actually take advantage of that rich upper rpm issue.

Per my discussions with several Toymod.org.au members large crank pulleys, on 1st gen. jdm 4agzes, do not cause the low rpm issues that they do on the udsm versions. None of their jdm 4agze's have ever needed a Grunt Box or standalone to use the large pulleys properly.

Additionally, none of the Aussie jdm 1st gen. 4agze's have upper rpm issues either, whether lean or rich. Not to say that a standalone wouldn't improve things, but they are not a requirement.

There are a number of Aussie m/t and a/t owners that use the large pulleys, and there do not appear to be any significant differences in how the large pulleys affect either a m/t or a/t.

USDM 1st gen. 4agze's definitely have knock sensors, and I was pretty sure that the rest do as well, but it's been awhile since I checked into that.

The lack of upper rpm power sounds a lot like what happens on the 2nd gen. 4agze's. They use different knock sensors, and ecu's and there is a confirmed problem where the knock signal, at approximately 5k rpm (with a large pulley), starts retarding the timing significantly, and kills off power. The only real workaround to this so far has been to either swap out the knock sensor and ecu for different/earlier versions, or to install a standalone.

As to the upper rpm hp loss discussed by the OP, I am guessing that it may well be due to the belt slippage that they have now apparently discovered. SC lobe wear could also be an problem. Both of those will cause more of an issue at high rather than low rpm.

As for the WI discussion, many over here have tinkered with it (on their 1st gen. 4agze's), but I haven't read of any that have perfected it yet. Sure it will greatly reduce the intake temps on a 4agze w/o intercooler, but so does an intercooler. It won't heat soak like an intercooler, but is it worth the hassle, and alterations for many users? Most people here find that a simple ic fan, on an oem intercooler, provides more than enough cooling when using a large pulley. A good ic fan setup will probably neither impair nor improve 'at speed' ic temps, but will greatly improve slow speed/idling ic temps. For heavily driven daily drivers they can be very useful, and cost effective.

[PW@Woodsport]

Thanks for all the replies folks. Given the car is an auto I doubt I'll ever be doing trackdays in it so I'm not too worried about going crazy on water cooling etc. Also because I'm in Scotland where the ambient temperature is rarely in double figures (well nearly) I don't think I'll have too many problems in day to day driving.

I might look at improving air flow through the IC but I think that should suffice. Based on the comments before it doesn't seem there is any easily available electronics that will be suitable either and I'm not keen to run experiements on my car until I know what I'm doing with the basics!

Since getting the mods done I have noticed a belt slip when at full boost so will need to get that tightened up. Also when at idle there is a noticable high pitched rubbing sound from the supercharger pulley area (not the cam pulley) which sounds like the pulley needs oiled. It's quite loud and noticeable. Anyone else had this after fitting the larger pulley? Just sounds like it isnt smooth... sure its not a big deal but want to check.

Cheers
P

Hi Paul, the belts should have been sufficiently tight, perhaps the new one has stretched slightly since fitting, i don't like to over tighten these belts as it puts unneccesary strain on pulleys/bearings etc.

You have two belts, one for SC and one for Alt/AC, take the Alt/AC one off (5 minute job) and see if the sound goes away, also try some Wd40 or oil on the V6 idler pulley bearing, it may be a little dry.

Pulley noises can be annoying so if you need anything just ask.

[Lauren]

It's very common for SC belts to slip with a big pulley. Some dress the belt and that can help. You normally need to do them pretty tight to stop the slipping.

It's the bane of having a big pulley I'm afraid.

[PW@Woodsport]

After Laurens post i probably haven't tightened it enough, i have a good feel for how tight a normal belt should be, so it would appear the oversize pulley needs the belt tighter than normal, can't say i approve of overly tight belts but if needs must....

[Lauren]

It's not ideal and tbh I hate over tightening them, but they really do have a tendency to slip which is just because the pulley is so big and it was never designed to have this.

Others have reported good results with belt dressing to help increase the grip on the pulley.

The only permanent solution is to have a toothed belt and corresponding pulleys, but that won't be cheap!

[PW@Woodsport]

I may have to rethink the alternator mounting on that 86 SC conversion Lauren, i've run the alt from the SC belt, so less of the belt is running around the oversize crank pulley now, so that will probably slip.

I knew there was a reason to keep the alt on the front pulley by itself... back to the drawing board!

[Fab4MR2]

You might also want to look into getting something like a Gates racing belt, which is made with a slightly better friction material in the rubber (epdm), and also uses aramid/kevlar fibers for non-stretch reinforcement. Don't know how available they are over there though.

Power Enterprise used to make one of those just for the 4agze, so that the Japanese could run they're small 106mm TBS sc pulleys without slippage, but that has been discontinued for a bit, and was more a normal belt size.

[pk_090]

HKS do harcore super kevlar belts for the 20V i know for definate, notsure about the 16V, and how much differance in belt lenght there is between the 20V and the 16V.
Alex