LS1 ECU to 240SX S13 speedo

There has been a lot of mis-information on the web about exactly how the S13 gauge cluster operates.  Hopefully this article clear things up.

First of all, everyone that said 2k, 4k or 8k ppm for the gauge cluster is wrong. 60Hz AC sine wave, ~3V p-p into Y/L with Y/B grounded gave me 13mph.  This means the gauge cluster needs 16,000 pulse per mile by the following calculation:

60Hz * 3600 sec/hour * 13 mile/hour = 16,000 pulse / mile

You also don’t really need a Dakota Digital box, unless you like to blow $70.  Reason being the LS1 ECU can be configured using HP tuners to give the correct 16,000 PPM output.  (VSS Output Pulses per mile)



However, the LS1 ECU send out a DC square wave, 12v p-p.  It looks like this:




The s13 gauge cluster needs to see 0 crossing on the Y/L line.  Instead of using a dakota digital box, go to radio shack and build this.




The  circuit is not all that complicated.  I crammed it all together, put some heatshrink tube around it and tied it into the main dash harness.














Voila!  Although it is not a perfect sine wave, the s13 gauge cluster will happily give you an output using the following waveform.




I will be spending the next 3 weeks (or since I am writing this in retrospect, spent) on some un-disclosed activity (fingers crossed). Not having the mount kit from Sikky gave me a good reason to take a break also. This is the way the garage will sit for about a month…

Clutch Slave

It is interesting going from a 20 year old car to a 10 year old car – so many things change. For example: the 240 clutch hydraulics run off simple brake hoses and flared fittings, while the T56 clutch utilizes a combination of braided lines and proprietary fittings (what is this needle-ball fitting that cost $12?). To mate the 2 together, one not only need a new clutch MC, but a series of -3 and -4 AN lines to pipe it all together.

Pressure side – 36″ banjo to -3AN, connected to the mysterious and expensive needle ball Russell fitting
Bleed side – 12″ -4AN, to 10mm female flare, to 10mm bleeder valve

You can buy everything together in a kit, but this was my first opportunity to work with AN fittings and I was not about to give up the fun. Sourcing all the parts together from summit and Pegasus was rather like playing lego (or ochem for the real nerdy type).

A closeup of the finished slave cylinder:

Hope it don’t leak

New bench vise!

No workshop is complete without a bench vise. I recently acquired the addiction of buying things dirt cheap on ebay, but for some reason 40lb of metal don’t seem to lose their value. After 2 weeks of searching I gave up and pulled the trigger on a new one:

Wilton 63302 6-Inch, $149.99 shipped from Amazon. I don’t know how Amazon gets away with it, probably cost them $30 to ship this. Maybe I should buy couple bags of concrete with Prime just to break the system. Anyhow, the vice is outstanding. Wilton made the jaws and leadscrew with tight tolerance, the package almost feels like a Kurt CNC vice. I’m going to feel bad hammering on the handle when I do use the vice as a press 🙂

To top things off, I got me some Aeroquip soft jaws to go with. Crimping AN fittings = so easy, a caveman could do it

Fuel pump upgrade

Who would know 5.7L of dino juice burning power would outrun the original fuel pump that came with the 240. It seems that I too, can’t avoid the most common upgrade – the infamous Walbro 255 fuel pump.

Make sure you buy the whole kit for the specific car! Sometimes the pump will come as just the pump, without the rubber isolator at the bottom. This will make the pump hang by the hose, probably not a good idea. Quick eBay search gave the appropriate kit for the S13.

The process went smoothly, since I’ve previously pulled the pump just out of curiosity. Mark the pressure and return hose on the pump housing before you disconnect it (they look exactly the same).

I was quite surprised to find every part inside of the fuel tank to be in pristine order – apparently things don’t rust in gas fume! The pump, hoses and clamps all look like the day they were made. Felt like I was working on a 1 year old 240.

Not a big fan of using crimp noodles to join wires, would have preferred to solder the wires onto the pump cover terminals directly. At this point the gas fume was getting out of control and I simply wanted to close it up.

Beware of people, not eBay

It used to be cool to roll with the windows down in 100 degrees of heat, knowing that saving 40lb from not having AC is awesome. Not anymore. How can I drive when I’m sweating faster than the US budget deficit increase?

Unfortunately, some idiot decided to yank out all the HVAC pieces and sent them to the dumpster in St. Louis. No worries. People are parting out 240s all the time. I bought me all the interior HVAC stuff from a dude on eBay for $175 shipped. For $175, you would think the guy could at least throw some newspaper in there to pad the box. I guess someone is cheaper than I am

Naturally, the pieces got a little beat up. I thought no sweat, a little duct tape never hurt anyone. It was before I spotted these little critters crawling around

Good god, what kind of person let fleas infest his car? This really put me over the edge. Damaged parts ok, I can deal. Fleas crawling everywhere? No. Homeboy total refused to fund me the $175, stating that damaged shipping is not his fault, and one can expect fleas from “slightly used parts”.

You might say wait, you bought this through eBay / Paypal, aren’t you covered under their buyer protection program? Well yes, but lets remember eBay / Paypal only makes money if you complete a transaction. I filed a complaint and am still waiting to hear back after a week! Ended up picking the phone and calling Visa. Got my money back with in a day. What did you learn?

Do not trust anyone
Never pay paypal transactions by bank transfer. BOA can care less about how you got screwed