Offroad-Express

Here is one of several interesting little problems I had to overcome when converting from my 1980s carbeurated engine to a 1990s fuel injected computer controlled engine.

I decided to go with the stock computer on my install both because of cost, and because of the wealth of wiring/computer information regarding conversions using LT1 350 chevs (thanks to all the US hotrodders). Stock engine computers are also ALOT more sophisticated than aftermarket computers which usually means better fuel economy and more functionality, the downside being you have to deal with extra sensors if you want to retain this functionality.

A bunch of these sensors have not been used in my install, but one that I retained was the vehicle speed sensor. The VSS tells the engine computer how fast the vehicle is going and uses this to calculate fuel mixtures and other operating parameters. For example at highway speeds the computer turns the engine fans off and when not under hard acceleration will adjust the fuel tables for economical highway driving. The VSS has a magnetic pickup and is usually located inside the gearbox, reading 40 pulses for every single turn of the driveshaft. This meant that to run the sensor on my install I had to somehow also read 40 pulses per rev of the driveshaft.

I was reading up how to tackle this problem on the US hotrod forums and found a guy named Paul Sutton who has an LT1 in his 80 series cruiser who was asking the same questions. I emailed him to see if he had managed to solve the problem and wouldnt you know it he lived in Auckland! He had dealt with the VSS by adding a 40 tooth reluctor wheel to the output flange of his transfer case, and mounted the sensor using the transfer case cover bolts. Wouldnt you know it he had a spare wheel having originally milled up two and being a kind fellow sent me the spare one for the price of a bottle of whiskey

I then had an alloy sensor mount tigged up which bolts to the rear of my transfer case (alloy to avoid signal interference with the magnetic pickup). The setup is shown in the below pics, after programming diff ratios and tyre sizes into the computer my ecu now knows how fast Im going

In terms of other computer stuff for the conversion, the same kind chap who gave me the VSS reluctor wheel offered to reflash my engine computer as well

The vehicle anti theft system (VATS) was programmed out of the ECU along with air conditioning and auto transmission codes. Although the LT1 uses a mass airflow sensor and a manifold absolute pressure as a backup, I chose to just run the MAP sensor.

Being a US engine there was a bunch of emissions equipment on the engine and in order to try and simplify the install I removed these. The exhaust gas reflux (EGR) system recycles unburnt exhaust gases from the exhaust back into the intake manifold. This function was deleted from the ECU and I made up some stainless plates to cover the holes left in the intake manifold. I didnt need to plug up the holes on the exhaust manifolds since I was having new custom headers made

In terms of tuning I ordered an email 'power tune' from MADZ28.com, a camaro/corvette tuner that came highly recommended from the V8 crazy americans on the US hotrod forums. I gave him all the specs of my engine, quoted the length of the header primaries etc and he emailed me back the tuning file and some software to flash the ECU. I also ordered a USB to serial data cable off the net and wired it into the serial data and ECU earth at the back of the ECU.

I mounted the ECU in the glove box and now have a USB port on the dash, I can plug in my laptop and get real time data re engine operating parameters using data logging software. Below is a screenshot...

OK last post hopefully so here's a summary of the remaining mods, cert process and a few action pics.

So with the engine in, suspension sorted, little rust removed and body work painted, it was time to install the exhaust, wire the bitch up and drive the sucker! I used a relay box from a nis*an sylvia (braces for flame) and used the relays and fuses in this for all the chevy related stuff, the lights/remaining toyota electrics stayed in the original toyota fuse box.

I had custom mandrel headers made for the donk since this was an easy way to get some extra ponies and if you're gonna spend money on an engine and tyres and bellhousing kit and...errrrrr you get the idea...

The headers run 4 into 1 and have oversize, midlength primaries that run into 3" collectors. They are HPC'd and definitely look the business, wish I hadve taken pics outa the truck but alas never got around to it. The exhaust is also 3", full mandrel with a single muffler, the bitch is LOUD, not shitty loud but kickass thundery setoff car alarms loud. Its not overly droney on the open road but is definitely capable of making babies cry and scaring old people.

I had a coldair box tigged up for the passenger side and am running a large pod close to the passenger guard. I want to eventually build a snorkel for that side (off the shelf ones plumb to the drivers side) and then plumb this to the sealable cold air box. I also didnt want to put on a 3" snorkel given that the minimum diameter of the stock intake is 3.5", so future mods may include a 4" custom snorkel.

Cooling wise I used the stock cruiser rad and picked up a ford taurus electric fan off ebay for about $100 IIRC. These fans flow MASSIVE amounts of air for an electric fan and Id definitely recommend to anyone who is having problems with cooling. They are two speed fans and flow more air on low than most (more expensive fans) do on high. Other cooling stuff...the camaro radiator has multiple inlets and oulets so I had to tap the water pump housing of the LT1 to plumb back in one water line that otherwise had nowhere to go.

Certification was pretty easy (I was FARKN nervous cause I was moving islands in 1 week at the time). The new extra wide/low backspacing wheels stuck way outa the guards so I imported some 3" flexi flares from the US to pre-empt that cert issue, only thing I got picked up on was that I needed to brace the longer shackles. An excursion around Chch metal retailers and a couple of hours in the shed and the fix was done, had it back at the certifiers and signed off the same day. One thing I was worried about was the brakes. Id heard that the big heavy 60 series were prone to getting picked up on brakes during certification, but fortunately the surf callipers passed the cruiser with flying colours. Oh yeah did I mention the KZN130 ('95 surf) callipers and new rotors? Id definitely recommend this bolt-on calliper upgrade to anyone with an 80s cruiser or hilux, the difference is night and day.

One final mod that came after cert and after my move/roady to the NI was a diff regear. My truck originally came with ultra poo 3.7 diffs, and with the 35"s one thing I was kinda dissapointed with was the gearing. Even though I had doubled my horsepower, with the WAY larger than standard tyres I pretty much had a 4-speed, since in 5th at 100kmh I was doing about 1500 rpm. I came across some (needle in a haystack) 4.56 stock landcruiser diffs in a truck being wrecked (the very same HJ60 being advertised for parts on ORE at the moment). Unfortunately the rear was a semifloat and my rear is a fullfloat, so I ordered new ring and pinions from the states for the rear (which means there is a semifloat 4.56 landcruiser diff up for grabs if anyone is interested...). A mate of mine happened to be in the states at the time so I added a lockright locker to the order and he brought the whole lot over with him free of charge Setting up a diff was starting to stretch my level of mechanical expertise so I enlisted the help of my dad (the mechanic) and we spent the weekend removing, setting up, and replacing the diffs. I have JUST finished running in the new gears in the rear and the truck now drives awesome. The truck pulls alot harder and 4wd low is nice and crawley. I now sit at about 2.5k rpm at 100 kmph and my speedo is back to stock to boot.

Other neat little mods/fixes off the top of the head...tach correction was achieved via a 50c 200ohm potentiometer from jaycar wired inline from the coil (vs. $140 AUD kit from MARKS 4wd adaptors), speedo correction (pre diff regear) pull the needle off and pretension the spring.

Right piccies of the final product!!!!!!


Front and rear rainy pics....


















New flares and wheels








Engine bay bling








Left header bling pre coating









Right header








OK action pics tomorrow I got to hit the sack

LT1-62 wrote: Other neat little mods/fixes off the top of the head...tach correction was achieved via a 50c 200ohm potentiometer from jaycar wired inline from the coil

Thats the piece of info I never had, read somewhere about shun (shunt?) resistors accross the tach but wasn't sure and just left it in the too hard basket

I'll give it a try next time I've got a list of things to fix on the truck
.....thanks for the info!

Hey sadam, check out this link:

http://forum.ih8mud.com/showthread.php?t=20777

The reason you use a pot instead of a resistor is so you can calibrate it with an aftermarket tach. In my case I used the real-time rpm readout from me laptop.

Heres a few dirty pics of the functioning end product, nothing too challenging...

































The final pic is of me mates Jack Russel pup, he looks a bit different these days....

coming soon....stowable double bed, safari rack canvas cover/tarp.

LT1-62 wrote:Hey sadam, check out this link:

http://forum.ih8mud.com/showthread.php?t=20777

The reason you use a pot instead of a resistor is so you can calibrate it with an aftermarket tach. In my case I used the real-time rpm readout from me laptop.

Got that link stashed away in my favourites now,
My engine dosent have any RS232 ports on the side to download data so I guess I'll have to stick a 8 cly calibrated tacho (just gave one away) onto it and determine the speed/RPM and then try and calibrate the 6 cly one to the same with the pot?

Hmmmm..... or maybe I could do a tempory 2 way switch to keep switching between tacho's (don't know if you can run 2 simultaniously) to calibrate the 6 cly off the 8 cly one?

Thanks for the info LT1-62.

Just get hold of an 8 cylinder tach and wire it straight to the coil, the pot will have a little adjustment screw on it and turn it clockwise/anticlockwise til both tachs read the same

oh yeah, couple more pics while I remember: coated headers...

great work, can i ask wot the engine conversion cost ya? it would go nicely in a swb truck with coils, simexes and difflocks.. wot sort of horsepower is she putting out?

what clutch are you running with your LT1, I have the same engine in my Nissan Safari and yes Paul Sutton is a very kind guy. I run Tunercat for my programming, same as Paul
Looks like you have done a great job there

Hi Worthog, I used a high rated pressure plate (PBT) and performance chevy disc. PBT clutches (ie repco clutches) are apparently super duty, the guy at clutch systems in christchurch tested the repco pressure plate on his machine and basically said he couldnt get any stronger, he then sold me an uprated SBC disc to suit.