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post #1 of 34 (permalink) Old May 23rd, 2019, 11:05 Thread Starter
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SC crank pulley

I am sure that this has been covered before, but I am way late to the party. I have been told that to get a little bit more boost on my 89 SC, I can replace the crank pulley (and associated belt (s)) with an oversized pulley such as HKS, Blitz, Fensport, NST, Cusco, etc. I am having serious difficulty finding these parts. Any suggestions? Used parts are acceptable.
Thanks
Paul
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post #2 of 34 (permalink) Old May 23rd, 2019, 11:49
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post #3 of 34 (permalink) Old May 23rd, 2019, 12:58 Thread Starter
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SC crank pulley

Thanks Mikemo!
I did some more searching and found this: https://www.shopnonstoptuning.com/st...NST04180K.html
Any thoughts on the above NST vs the TTT link you provided? The TTT kit does not include a water pump pulley where as the NST does. Any thoughts?
Thanks and I hope to hear from the forum soon.
Paul
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post #4 of 34 (permalink) Old July 8th, 2019, 06:17
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I’m curious to hear the response. I’ve been saving up to replace my pulleys, but haven’t really settled on the specifics.
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post #5 of 34 (permalink) Old July 9th, 2019, 08:30
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I don't have any experience with the other pulleys. They all do basically the same thing; get the supercharger to spin faster. Make sure everything in the mounting area is clean and in good shape, and use a new woodruff key when installing the new pulley.

You also need to do what's called the "ABV mod" to allow the extra boost to get to your engine. There are lots of posts here that discuss it.

Keep in mind that the stock USDM ECU does a poor job fueling the engine when a big pulley is used. The engine tends to run lean at low RPM and large throttle openings. You can buy a "grunt box" to fix that. I'm also working on an open-source DIY solution for the same problem.

Good luck
Mike M.
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post #6 of 34 (permalink) Old July 9th, 2019, 09:58
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Nevo Pulley 170 or 175mm - Discontinued (I have this 175mm)
HKS
Blitz
Cusco
NST (Non-Stop Tuning)
ELP : Doubt this exists anymore
Ross ? Very pricey but probably worth it if you are concerned about harmonic balancer
Speedchaser Supercharger pulley. (This is an actual smaller SC pulley made in small runs back in the early 2000's. I had one but never used it and sold it.

There are more but those are the ones off the top of my head.
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post #7 of 34 (permalink) Old July 9th, 2019, 10:00
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Quote:
Originally Posted by mikemo View Post
I don't have any experience with the other pulleys. They all do basically the same thing; get the supercharger to spin faster. Make sure everything in the mounting area is clean and in good shape, and use a new woodruff key when installing the new pulley.

You also need to do what's called the "ABV mod" to allow the extra boost to get to your engine. There are lots of posts here that discuss it.

Keep in mind that the stock USDM ECU does a poor job fueling the engine when a big pulley is used. The engine tends to run lean at low RPM and large throttle openings. You can buy a "grunt box" to fix that. I'm also working on an open-source DIY solution for the same problem.

Good luck
Mike M.
Back when my 87SC swap car still ran I think I was looking into finding a JDM ecu. From what I remember it's plug and play and gets rid of the lean out without having to use a Grunt Box. I have the Grunt box but the less custom stuff the better when it comes to things like this.
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post #8 of 34 (permalink) Old August 20th, 2019, 20:59 Thread Starter
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Well, I finally got the pulleys installed (Techno Toy Tuning) and have done the ABV modification. The car runs a little bit stronger but perhaps it is still in the "learn" mode. Or is this a myth?
By the way, don't waste your time with NST (Non stop Tuning). They were very responsive before they got my money. After they got my money, they tried to screw me by sending me nothing. I was patient and then finally cancelled my order. NST ignored my request to cancel (3 times) and would not reply to me. I have filed a dispute with my credit card company and it looks like I will get my money back.
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post #9 of 34 (permalink) Old August 22nd, 2019, 15:31
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Years ago when I did the smaller HKS crank pulley, I had a similar feeling of the power not being significantly more than stock. The reason is because the the boost curve is just about as flat as stock. The butt dyno can't feel the extra power.

I went to the track and suddenly noticed that my entry speeds at all the corners were 20 MPH faster. I needed to move my brake points significantly earlier.

Totally worth it.
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post #10 of 34 (permalink) Old September 6th, 2019, 21:22
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I really wish smaller pulleys were still being sold. If anyone has a 160-170 mm pulley, I'd be very interested in buying it. 175mm from T3 and 180mm from NST seems like a bit too much, especially when Grunt Boxes aren't being made anymore. Plus I hate the idea of using a piggyback system to mess with my fuel ratios, or replacing the entire ECU with a megasquirt system.

Does anyone run a 175 mm pulley with no additional fuel mods? Besides a wideband of course.
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post #11 of 34 (permalink) Old September 7th, 2019, 19:54
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I have looked over the website for the Gruntbox and it looks like a very simple circuit using an ATtiny microprocessor. Back when the gruntbox was created, you probably needed to be a fairly sophisticated electronics hobbyist to design and produce the gruntbox. But today you can buy almost all the parts in one package for as little as $3 (that's slow boat from China, $5 to $10 if you want it 2 day amazon prime).

It's called a Digispark and it looks like this:

Basically you would have to add a few resistors, a potentiometer, a MOSFET and a transistor that drives the MOSFET to duplicate the Gruntbox. You could even eliminate the potentiometer and just reprogram the chip if you were willing give up on-the-fly throttle trigger adjustment. The Gruntbox has one ignition input for RPM detection, one throttle position input for boost trigger detection, two inputs from the cold start sensor relay and one output for the MOSFET to turn on the cold start injector. The program running on the microprocessor would detect when the engine is running between a minimum and maximum RPM and the throttle is above some threshold. If true, turn on the cold start injector. Also it would sense when the cold start would normally have been on and turn on the cold start injector. (if you wanted to triple the cost for more accuracy, you could use a MAP sensor instead of throttle position)

Any electronics hobbyist could probably build one for under $10. Any clueless idiot would probably need to spend between $50 and $100 to buy the tools and learn how to do it themselves.

Unfortunately, I have no need for a Gruntbox and I have no desire to sell one (also my car is unavailable for testing right now). However I would be happy to help anyone who wants to do it themselves. First the cold start sensor relay needs to be tested, then the simple details like the correct resistor values, which MOSFET has the right voltage and current limits, the RPM range, and throttle trigger value need to be worked out. (the Arduino Nano microprocessor is overkill at about 3 times the size and cost of the Digispark but would be MUCH easier for design and testing - the Digispark does not allow live USB printout/configuration during testing)

I also get the feeling that very few people are even interested in a Gruntbox these days. But it would be nice if an open source gruntbox existed for those few people.
Attached Images
File Type: jpg Digispark.jpg (192.6 KB, 48 views)

Last edited by edmcguirk; September 9th, 2019 at 11:05.
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post #12 of 34 (permalink) Old September 8th, 2019, 20:23
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In early 2018 I did pulley's on my SC, and decided to come up with my own fueling solution. I bought multiple circuit boards from amazon and spent about $35. After using it for 2 seasons I trust that it would work for others. What I used was one DC 12V 2-Ch Voltage Comparator, Frequency To Voltage Conversion Module 0-200Hz To 0-10V F/V Conversion Module Digital To Analog Converter Module, and a DC 12V Coil 8 Pin Dpdt Power Relay. A handful of wire and a set of crimp connectors. It turns on the cold start injector based on RPM and throttle and the transition set points are adjustable. I can get photos and draw up a circuit diagram if anyone is interested.
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post #13 of 34 (permalink) Old September 8th, 2019, 20:48
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Quote:
Originally Posted by bob45228 View Post
In early 2018 I did pulley's on my SC, and decided to come up with my own fueling solution. I bought multiple circuit boards from amazon and spent about $35. After using it for 2 seasons I trust that it would work for others. What I used was one DC 12V 2-Ch Voltage Comparator, Frequency To Voltage Conversion Module 0-200Hz To 0-10V F/V Conversion Module Digital To Analog Converter Module, and a DC 12V Coil 8 Pin Dpdt Power Relay. A handful of wire and a set of crimp connectors. It turns on the cold start injector based on RPM and throttle and the transition set points are adjustable. I can get photos and draw up a circuit diagram if anyone is interested.
What size pulley? I mean... if you're willing to sell a plug and play one... name your price
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post #14 of 34 (permalink) Old September 8th, 2019, 21:11
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What size pulley? I mean... if you're willing to sell a plug and play one... name your price
It's an older boost junke pulley with the harmonic balancer. I think a 175mm. Not looking to make these, but it is really simple DIY project just running wires from board to board, no soldering. I'll take a pic tomorrow and post.

Last edited by bob45228; September 8th, 2019 at 21:31.
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post #15 of 34 (permalink) Old September 9th, 2019, 08:09
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Originally Posted by edmcguirk View Post
I also get the feeling that very few people are even interested in a Gruntbox these days. But it would be nice if an open source gruntbox existed for those few people.
Good timing.
Hardware and software are done. I was going to release the design after I tested it in my car, but if someone wants to jump ahead, I'm game. I won't be getting the engine installed until fall.

Mine also has an output for an externally mounted LED, and a disable switch can be added if desired (while still keeping the CSI functioning).

Parts cost is well under $10.


Last edited by mikemo; September 9th, 2019 at 08:13.
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post #16 of 34 (permalink) Old September 9th, 2019, 19:57
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Here is what i put together using existing boards from amazon.
In the first attachment.
Right board converts frequency, from the igniter pulse, to voltage.
Left board has 2 circuit relays that trigger when the voltage goes above a threshold value, one reading TPS signal, the other the voltage output of the frequency board.
When both are true, throttle at 60% and greater(or whatever voltage you choose) and RPM below 3500 RPM or again what ever you choose, it triggers another relay that selects 12v to send to the cold start injector.
In the second attachment.
Not nearly as simple and elegant as your solution.
Attached Images
File Type: jpg 20190909_183714.jpg (113.8 KB, 9 views)
File Type: jpg 20190909_183722.jpg (88.0 KB, 6 views)

Last edited by bob45228; September 10th, 2019 at 18:56.
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post #17 of 34 (permalink) Old September 9th, 2019, 22:36
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I like the off-the-shelf circuit mix and match to recreate a gruntbox but I am not sure I understand how your solution works.

When I first started looking at the gruntbox, I thought that all you had to do was supply voltage to the cold start injector but after reading the installation instructions on the gruntbox website I realized that something more complicated is going on with Toyota's MR2 cold start implementation.

I dug deeper into the workshop manual and electronic manual and found that one side of the cold start injector is directly hardwired to the starter motor solenoid. If you supply voltage there without first cutting that wire, the starter motor will engage. The other side of the cold start injector is attached to some sort of temperature sensitive relay that only allows a connection to ground if the engine is cold. If you cut both of those wires and supply switched voltage and ground to the cold start injector, everything will work when the car is at speed but the originally intended startup cold start injection will not function. If you do not cut those wires, the injector will not work when the car is warm and the starter motor will engage when the car is at speed.

Or at least that is the way simple addon electronic controllers would work. Smart routing of DPDT relays would leave the stock wiring intact in the default relay position but disconnect the stock wiring while supplying isolated power and ground to the CSI when the relay is activated.

Maybe a relay is slightly better than a solid state electronic circuit. (us electrical guys often do not consider mechanical relays)


edit:

Using a Digispark and a DPDT relay would cut the part count to a Digispark ($3), a dual SPDT relay module (10Amp? $1.50), and I think less then 3 resistors, maybe none. The wires, connectors, and container would be the most expensive parts. Hmm...

Last edited by edmcguirk; September 9th, 2019 at 22:57.
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post #18 of 34 (permalink) Old September 10th, 2019, 06:56
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bob45228,
That is a clever solution using off-the-shelf stuff. Nice work! I think that the way yours is set up that you've lost normal CSI function, but if you live where it's warm that's probably not an issue. Also, it looks like your CSI will fire if the engine isn't running and you open the throttle. Not a big deal since that's not normally what you'd do, but it is a drawback.

edmcguirk,
The "thermo-time" switch has two functions. It senses the coolant temp and doesn't allow the CSI to fire if it is above a certain level. Also, it only allows the CSI to fire for a short period of time before disabling it. That's likely to prevent flooding, and maybe to protect the CSI. Powering the CSI on the bench it was too hot to touch after only being open for a few minutes. Fuel in the line would probably cool it a bit, but that was alarming.

When you turn the key and the starter cranks, that is the +12v signal that is fed to the CSI and thermo-time switch. If you wanted to make this work without splicing into the thermo-time / CSI circuit, you'd have to steal the coolant temp signal, the starter signal, and you'd have to emulate what the thermo-time switch does mechanically in software. No doubt that could be done, but I think the most elegant way to do this is having to cut and splice a few wires (just like the original grunt box)

Maybe I wasn't clear, but all this work has already been done and I'm willing to share with whomever wants to play.

Instead of using a Chinese "digispark" I used my own circuit which uses a 8 pin DIP package Atmega ATTiny85, the same processor in the Digispark but without the clunky bootloader. The bootloader takes five seconds to start before the program runs, so the CSI function would be lost when the car is first turned on. That's no good. Also, the DIP package in a socket makes it easy to swap processors. The 6 pin programming header is on the board and can be programmed with an ISP. I used the Arduino development environment to write the software. There is a significant amount of available codespace and memory for enhancements. The custom PCB was designed with KiCAD and a small lot of boards were manufactured for about $2 each. There is a strip to solder the wires to, or you can load a screw terminal if you want to make it easy to remove later. You can (if you want) also run three wires up to the dash to provide an LED that shows when the CSI is being fired, and a disable switch if for some reason you want to deactivate the function but leave the CSI functioning as stock. I thought it would be cool to replace the supercharger LED on the dash with a bi-color one that would change color depending on if the CSI was enriching or not.

The reason I put this together is that I have a failed grunt box for my 88SC. The failed grunt box is likely the reason that the engine blew, but I can't prove that (happened to the previous owner). I did prove that the grunt box was not working and that the processor inside had failed. I don't know what type of processor it was as the guys who made it sanded the labels off of all the parts. I tried to contact someone to get a replacement chip, but never got a response. I figured that $150 saving was worth doing the work and that it might help some others in the MR2 community. It was also an interesting exercise.

If someone who is mechanically and electrically inclined needs to fix the lean condition after installing a big pulley, and wants to give this solution a try, let me know. Cover my cost (maybe $10?) and I'll send you a board ready to go. Just please feedback to me on how it works. We can always make software changes to tweak things.

I will post the code, hex, schematic and circuit board gerber files somewhere once this is all tested and proven. That way anyone can build one.

By the way, I called this "LCC", for Lean Condition Correction.
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post #19 of 34 (permalink) Old September 10th, 2019, 15:06
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bob45228,
That is a clever solution using off-the-shelf stuff. Nice work! I think that the way yours is set up that you've lost normal CSI function, but if you live where it's warm that's probably not an issue. Also, it looks like your CSI will fire if the engine isn't running and you open the throttle. Not a big deal since that's not normally what you'd do, but it is a drawback.
Actually, the relay is a double pole double throw and common is connected to the cold start injector. Flips to hot when engaged and re-connects to the thermo-time wiring when not. The relay is also wired so that it will not fire during start cycle as I grabbed a circuit that is dead on start and the control circuit feeds ground to the relay. You could, technically, turn the key to on and with the engine not running hit the accelerator and it would fire the CSI. So it could fire when not intended, but that really would not be a common situation.

Mike, I would be interested in trying your solution, but I would not be working on it for a couple months. If you still have it when the weather starts getting cold out I may buy one from you, but I would hate to take it if it is the only one and someone has the time to try it sooner.

Last edited by bob45228; September 10th, 2019 at 15:18.
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post #20 of 34 (permalink) Old September 10th, 2019, 16:13
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Oops, I wrote all this while bob45228 was replying. It may be all wrong.






I don't mean to disparage the LCC you have created. It looks like a very clean and functional design. Simple cheap parts and no dependencies on anyone else's products. Definitely the best choice if available.

I was thinking more along the lines of something that a novice could build for himself without having to get too deep into the electronics hobby. That's why I suggested the Digispark. The voltage regulator and USB are already there in one part. Once you publish the gerbers and code, anyone could duplicate your product but I think it would require someone maybe a notch or two above a novice electronic hobbyist. Not too hard but not super easy. I guess realistically, the learning curve from a Digispark to an ATtiny programmer is not that large. Maybe my preference for the Digispark is not significant.

I also like the idea of using a DPDT relay. You can just unplug or otherwise disable the ATtiny and the CSI will work exactly as a stock CSI should.

Different ways to skin a cat. Your product exists but my product is just an idea. I would purchase your LCC if I had a need for it and you were available. But a few years from now, if you were not available, I don't know if I would use your gerbers to order custom circuit boards or just solder a few wires between a Digispark and a relay module. (I think the chinese knockoffs of the Digispark make it a likely long term "generic" part)

Frankly, if bob45228 wired his relays the way I think he did, he has a functional product that requires no programming and no purchase of any electronics hobbyist tools. It's a little more expensive but it is simple. It seems to be a worthy second choice.

Let me describe the way I think bob45228's relays might be set up.

1 The frequency to voltage box is tapped into the ignition signal on the frequency side and output to one SPDT relay on the voltage side.

2 The tap from the throttle position sensor is input to the other SPDT relay.

3 Each relay input is adjusted so that it activates above a trigger throttle position and a trigger RPM.

4 One relay has the common pole attached to the CSI wire and the NC pole attached to the original starter solenoid wire. The NO pole is attached to 12V

5 One relay has the common pole attached to the CSI wire and the NC pole attached to the original "thermo-time" switch wire. The NO pole is attached to ground.

6 When starting a cold engine, the CSI will act normally as long as neither the throttle or RPM are above their triggers. In the unlikely event either one is above threshold, CSI will fail.

7 If either throttle or RPM is above threshold and the engine is warm, nothing improper will happen.

8 If the running engine is cold and only the throttle is above threshold (or the RPM is above threshold depending on which relay is attached to the starter solenoid wire), The CSI will improperly fire.

9 If both throttle and RPM is above threshold, the CSI will fire.

10 If the RPM is above the range of the lean condition and the throttle is above the threshold, the CSI will improperly fire but the amount of fuel coming from the CSI will be a smaller percent of the required fuel and the percent will be decreasing as RPM rises. Probably not a big deal.


Three wrong CSI modes but all of them are pretty minor.

Last edited by edmcguirk; September 10th, 2019 at 16:16.
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