Jump to content
SAU Community

Recommended Posts

Hello,

I am going to put a Nissan RB30 in an old Toyota Coaster bus. It seems the best engine for the job, and although I have not yet bought one, I assume I will be fitting something from a late 80s Skyline with the 3 litre EFI motor. (They fit my budget, they will fit in the bus, they seem a nice quiet motor and everything I have heard about them is good so far.)

The bus is currently helped along by a 2.4 carbie motor (a Toyota R22) and it goes ok, but revs it's pants off at 100km/h (4200rpm). The motor is tired, and the gearbox is pretty ordinary too, so I figured I'd just pull the motor and transmission from the Nissan and fit them as a pair. I checked and I can get the tailshaft modded easily enough, which leaves the diff.

There are a heap of ratios to choose from, all the way from the current 6:1 diff (aarrgh!), through to about 3:1 from the diesel model.

The bus is not very hard to push (After all, the current tired 2.4 litre can do 110km/h if you wait a bit), probably a little easier to push than the Nissan Patrol that was fitted with the RB30, but certainly a lot more work than the sedan. The top gear ratios from the current five speed manual and the Nissan's 4 speed auto are about the same, so the 3:1 diff would give me 2100rpm at 100km/h, but somehow I suspect that is a little low.

So, my question is, what engine revs should I aim for at crusing speed? I'd like the engine to be running freely, not lugging, but I don't want it over revving either.

Your thoughts greatly appreciated,

Matthew

you won't want to have it rev too low as that will then decrease how well the motor pulls the bus (which is why the 2.4L is able to move it, because the diff ratio is as short as hell). considering that the rb30 in a commodore ran a 3.45:1 diff, that is the bare minimum you would want. it comes down to tyre size though. the patrols with the rb30 ran about a 3.9:1 diff to take into account bigger tyres, etc. and that is what i would be more inclined to run, or maybe even to around 4.3, depending on how big the tyres are.

now this may sound a bit odd hearing this on a skyline forum, but i would actually look at putting in a slightly later model commodore v6 or falcon straight 6. you can pick them up reasonably cheap from wreckers. there are 2 mains reasons why i suggest these. 1: parts are much more readily available 2: they both put out more torque than the rb30 (especially the falcon motors) and that is what you really need to lugging around something as heavy as a bus.

/\ +1 for the falcon motor. HEAPS more torque, and you could slap in a single rail borg warner box behind it, or even a C6 auto out of the F100 - F150.

If you can find a good alloy headed EFI 250 X flow I would go for that over the later 3.9 / 4lt, although the EF onwards 4tl with the variable length snail shell intake from the EL would be a great goer with a baby towing cam. You could set it up to pull around 2000rpm @ 110km and not worry about clagging up the heads with the high torque loading, and probably use less fuel doing it - eleventy billion taxi drivers cant be wrong

OK, most certainly not the response I was expecting... but really good points.

I do own an EF Fairmont Wagon with the funny intake, and it is the most incredible towing vehicle. The engine is very reliable, it pulls like a beast, but it drinks like a fish and steers like a cow. The stuff like the brakes, suspension and steering are pretty crummy, but I suppose they would not be put in the bus... I just feel like the engine would be almost too big, and the fact that it uses more fuel in the wagon than the bus currently uses makes me just a little nervous of what it would cost to run. Also, those engines have a list of issues a mile long. Each on their own is no big deal, lame head gasket, weak valves, crappy radiator, disposable power steering pump.... but they add up.

My experience of the commodores is only secondhand conversations, but when we did lots of caravan towing (yes, one of THOSE people) I found that the caravan people all stayed away from them. I am told they would crack heads and the transmissions could not handle the load. If you looked around a caravan park a few years ago, it was either Toyota Land Cruisers or Ford Falcons, as far as the eye could see, but this might have changed, it has been a few years.

I have read a lot of good stuff about the RB30, and I FEEL like it would be strong enough. The bus is only 500kg heavier than the patrol, with a much lower rolling resitance and I am unlikely to going much over 90km/h most of the time. I just thought if I got the revs right, it would work. But it seems like you guys have your doubts, and now I am worried.

The Ford solution is so logical, but... so terrrifying from a fuel and maintenance perspective...

nothing wrong with the RB, also there is a diesel variant around which might be an even better choice. RD28 or RD30 which lives in this among other things http://en.wikipedia.org/wiki/Nissan_Cedric_Y31. No idea what they are worth. Guess it all depends on time and money as with all things :D.

A big thanks to Grigor for your 3000 RPM suggestion and the calculation method also.

I tried to reply but I am too new (not enought posts) to be allowed to PM you back. But I would be keen to hear your thoughts on whether the engine is strong enough for the job also.

(5 more posts to go...)

Oh wow! I had completely forgotten the Cedric! And they were a brilliant car, but oh what a disastrous name... Did the diesel ever make it to Oz? I certainly never saw one...

Diesel is interesting. I started out thinking diesel, but the funny thing was, I had to drive about 100,000km to break even, and that was assuming some pretty conservative cost differences in the conversion.

Big upfront cost, but lots of really nice reliable engines to choose from if you have the money. (An Isuzu 3.4 litre turbo was nice, but at around $11K for engine and transmission, I lost interest really quick!)

I don't think the cedric diesel's ever made it to oz... but I think the Nissan Patrols did come in a GQ variant with an RD28T 2.8L Diesel Turbo.

Just looked up the specs on the RD28 (non turbo) and they are almost EXACTLY the same as the current petrol Toyota 22R motor. Not sure how a diesel would enjoy running at 4200 rpm for hours on end... could be messy.

Interestingly, the turbo version has a slight edge on the RB30 for torque, but only a few percent, so overall I would say the RB30 still feels right.

Sounds like fun.

Is this gonna have a turbo hangin off the side busboy?

Not if I can avoid it. Once you add a turbo the whole insurance thing gets tricky. I looked VERY hard at putting a turbo Volvo 740 motor in it (they are a pretty robust motor, I know, mine has 360,000km on it and is still going strong), but the whole parts thing had me worried. Then a bloke at the roads office pointed out the insurance companies would run for miles, so I went back to looking for a good petrol motor. That's when I found the RB30.

what about a 13B? yes I'm being serious. We almost imported a bus for a customer a while back, a Mazda Parkway 28 seater, and it had full log books (as required by the agency) for... wait for it... just over 1 million kms. Still ran the original engine. Needless to say we were bloody impressed.

A recieved a good comment re the RD28 turbo and the cost of getting one right. Yep, for those reading between the lines, this is a price sensitive conversion I am trying for here.

I am wise the fact that by compromising on cost I have to give up some aspect of performance, whether it be speed, reliability, economy etc.

When I looked at what was most important I realised initial outlay had to be low, (which ruled out diesel), then came economy (hence my fear of Ford motors), then came reliability (the RB30 seems to do well here) and finally, speed ( a Ford motor would be better here). So I guess I am resigned to accepting that this little bus is going to be no road burner. Really, if the current 22R motor and gearbox were not so tired, I think I'd happily up the diff ratio a little and live with the performance. But they are pooped, and an RB30 with auto just has to be a better option. Right...?

Two more posts and I can PM!

what about a 13B? yes I'm being serious. We almost imported a bus for a customer a while back, a Mazda Parkway 28 seater, and it had full log books (as required by the agency) for... wait for it... just over 1 million kms. Still ran the original engine. Needless to say we were bloody impressed.

Well, THAT was right out of left field! Nope, I have to admit, I would never have thought of it in a million years.... What's the logic here? Happy to rev at 4200 rpm of course, that would practically idle speed to a rotary.... I don't know much about them for torque etc, time to read a little.

Hmmm.....

Torque seems a little lower than I'd like (except on the turbo version, where it is insane), but then with those sorts of rev ranges maybe torque is not so important. I have never driven one so I can't really imagine how they'd translate.

Falcon or Commodore (Buick 3800) motor IMO...they've been done to death so there's no shortage of knowledge out there regarding conversions. Lots of people have converted Ford Transits to running the 3.8 litre with excellent results...some have even put a T56 behind that for something of a fail safe tow/carry vehicle. It's the Commodore automatic transmission that lets it down as a tow vehicle, they were always a weak item compared to the Ford...that said, my father always towed his speedboats with Commodore company cars and never ever had an issue.

RB30...sure it'll go better than the current engine but if you're spending the money/time on a conversion you might as well do it for a worthwhile increase in low end torque. Not to mention there's so many buick engines around that if anything ever goes wrong or you kill an engine you will always be able to find a spare / parts.

what about a 13B? yes I'm being serious. We almost imported a bus for a customer a while back, a Mazda Parkway 28 seater, and it had full log books (as required by the agency) for... wait for it... just over 1 million kms. Still ran the original engine. Needless to say we were bloody impressed.

Well, THAT was right out of left field! Nope, I have to admit, I would never have thought of it in a million years.... What's the logic here? Happy to rev at 4200 rpm of course, that would practically idle speed to a rotary.... I don't know much about them for torque etc, time to read a little.

Hmmm.....

Torque seems a little lower than I'd like (except on the turbo version, where it is insane), but then with those sorts of rev ranges maybe torque is not so important. I have never driven one so I can't really imagine how they'd translate.

Falcon or Commodore (Buick 3800) motor IMO...they've been done to death so there's no shortage of knowledge out there regarding conversions. Lots of people have converted Ford Transits to running the 3.8 litre with excellent results...some have even put a T56 behind that for something of a fail safe tow/carry vehicle. It's the Commodore automatic transmission that lets it down as a tow vehicle, they were always a weak item compared to the Ford...that said, my father always towed his speedboats with Commodore company cars and never ever had an issue.

RB30...sure it'll go better than the current engine but if you're spending the money/time on a conversion you might as well do it for a worthwhile increase in low end torque. Not to mention there's so many buick engines around that if anything ever goes wrong or you kill an engine you will always be able to find a spare / parts.

So maybe a manual commodore trans would overcome the main problems with the commodore option? I must say I liked the V6 config as it allowed me to move the C-of-G back a bit further. The bus was designed for a two ton payload on the back axle, and currently it is actually 100kg lighter than when I bought it empty due to removing the seats and doing a VERY lightweight conversion of the interior.

Is there a commodore engine that has a particularly good reputation (except the RB30 VL of course!)

(Good point about not skimping on cost to the point of silliness too.)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Any update on this one? did you manage to get it fixed?    i'm having the same issue with my r34 and i believe its to do with the smart entry (keyless) control module but cant be sure without forking out to get a replacement  
    • So this being my first contribution to the SAU forums, I'd like to present and show how I had to solve probably one of the most annoying fixes on any car I've owned: replacing a speedometer (or "speedo") sensor on my newly acquired Series 1 Stagea 260RS Autech Version. I'm simply documenting how I went about to fix this issue, and as I understand it is relatively rare to happen to this generation of cars, it is a gigantic PITA so I hope this helps serve as reference to anyone else who may encounter this issue. NOTE: Although I say this is meant for the 260RS, because the gearbox/drivetrain is shared with the R33 GTR with the 5-speed manual, the application should be exactly the same. Background So after driving my new-to-me Stagea for about 1500km, one night while driving home the speedometer and odometer suddenly stopped working. No clunking noise, no indication something was broken, the speedometer would just stop reading anything and the odometer stopped going up. This is a huge worry for me, because my car is relatively low mileage (only 45k km when purchased) so although I plan to own the car for a long time, a mismatched odometer reading would be hugely detrimental to resale should the day come to sell the car. Thankfully this only occurred a mile or two from home so it wasn't extremely significant. Also, the OCD part of me would be extremely irked if the numbers that showed on my dash doesn't match the actual ageing of the car. Diagnosing I had been in communication with the well renown GTR shop in the USA, U.P.garage up near University Point in Washington state. After some back and forth they said it could be one of two things: 1) The speedometer sensor that goes into the transfer case is broken 2) The actual cluster has a component that went kaput. They said this is common in older Nissan gauge clusters and that would indicate a rebuild is necessary. As I tried to figure out if it was problem #1, I resolved problem #2 by sending my cluster over to Relentless Motorsports in Dallas, TX, whom is local to me and does cluster and ECU rebuilds. He is a one man operation who meticulously replaces every chip, resistor, capacitor, and electronic component on the PCB's on a wide variety of classic and modern cars. His specialty is Lexus and Toyota, but he came highly recommended by Erik of U.P.garage since he does the rebuilds for them on GTR clusters.  For those that don't know, on R32 and R33 GTR gearboxes, the speedometer sensor is mounted in the transfer case and is purely an analog mini "generator" (opposite of an alternator essentially). Based on the speed the sensor spins it generates an AC sine wave voltage up to 5V, and sends that via two wires up to the cluster which then interprets it via the speedometer dial. The signal does NOT go to the ECU first, the wiring goes to the cluster first then the ECU after (or so I'm told).  Problems/Roadblocks I first removed the part from the car on the underside of the transfer case (drain your transfer case fluid/ATF first, guess who found out that the hard way?), and noted the transfer case fluid was EXTREMELY black, most likely never changed on my car. When attempting to turn the gears it felt extremely gritty, as if something was binding the shaft from rotating properly. I got absolutely no voltage reading out of the sensor no matter how fast I turned the shaft. After having to reflow the solder on my AFM sensors based on another SAU guide here, I attempted to disassemble the silicone seal on the back of the sensor to see what happened inside the sensor; turns out, it basically disintegrated itself. Wonderful. Not only had the electrical components destroyed themselves, the magnetic portion on what I thought was on the shaft also chipped and was broken. Solution So solution: find a spare part right? Wrong. Nissan has long discontinued the proper sensor part number 32702-21U19, and it is no longer obtainable either through Nissan NSA or Nissan Japan. I was SOL without proper speed or mileage readings unless I figured out a way to replace this sensor. After tons of Googling and searching on SAU, I found that there IS however a sensor that looks almost exactly like the R33/260RS one: a sensor meant for the R33/R34 GTT and GTS-T with the 5 speed manual. The part number was 25010-21U00, and the body, plug, and shaft all looked exactly the same. The gear was different at the end, but knowing the sensor's gear is held on with a circlip, I figured I could just order the part and swap the gears. Cue me ordering a new part from JustJap down in Kirrawee, NSW, then waiting almost 3 weeks for shipping and customs clearing. The part finally arrives and what did I find? The freaking shaft lengths don't match. $&%* I discussed with Erik how to proceed, and figuring that I basically destroyed the sensor trying to get the shaft out of the damaged sensor from my car. we deemed it too dangerous to try and attempt to swap shafts to the correct length. I had to find a local CNC machinist to help me cut and notch down the shaft. After tons of frantic calling on a Friday afternoon, I managed to get hold of someone and he said he'd be able to do it over half a week. I sent him photos and had him take measurements to match not only the correct length and notch fitment, but also a groove to machine out to hold the retentive circlip. And the end result? *chef's kiss* Perfect. Since I didn't have pliers with me when I picked up the items, I tested the old gear and circlip on. Perfect fit. After that it was simply swapping out the plug bracket to the new sensor, mount it on the transfer case, refill with ATF/Nissan Matic Fluid D, then test out function. Thankfully with the rebuilt cluster and the new sensor, both the speedometer and odometer and now working properly!   And there you have it. About 5-6 weeks of headaches wrapped up in a 15 minute photo essay. As I was told it is rare for sensors of this generation to die so dramatically, but you never know what could go wrong with a 25+ year old car. I HOPE that no one else has to go through this problem like I did, so with my take on a solution I hope it helps others who may encounter this issue in the future. For the TL;DR: 1) Sensor breaks. 2) Find a replacement GTT/GTS-T sensor. 3) Find a CNC machinist to have you cut it down to proper specs. 4) Reinstall then pray to the JDM gods.   Hope this guide/story helps anyone else encountering this problem!
    • So this being my first contribution to the SAU forums, I'd like to present and show how I had to solve probably one of the most annoying fixes on any car I've owned: replacing a speedometer (or "speedo") sensor on my newly acquired Series 1 Stagea 260RS Autech Version. I'm simply documenting how I went about to fix this issue, and as I understand it is relatively rare to happen to this generation of cars, it is a gigantic PITA so I hope this helps serve as reference to anyone else who may encounter this issue. NOTE: Although I say this is meant for the 260RS, because the gearbox/drivetrain is shared with the R33 GTR with the 5-speed manual, the application should be exactly the same. Background So after driving my new-to-me Stagea for about 1500km, one night while driving home the speedometer and odometer suddenly stopped working. No clunking noise, no indication something was broken, the speedometer would just stop reading anything and the odometer stopped going up. This is a huge worry for me, because my car is relatively low mileage (only 45k km when purchased) so although I plan to own the car for a long time, a mismatched odometer reading would be hugely detrimental to resale should the day come to sell the car. Thankfully this only occurred a mile or two from home so it wasn't extremely significant. Also, the OCD part of me would be extremely irked if the numbers that showed on my dash doesn't match the actual ageing of the car. Diagnosing I had been in communication with the well renown GTR shop in the USA, U.P.garage up near University Point in Washington state. After some back and forth they said it could be one of two things: 1) The speedometer sensor that goes into the transfer case is broken 2) The actual cluster has a component that went kaput. They said this is common in older Nissan gauge clusters and that would indicate a rebuild is necessary. As I tried to figure out if it was problem #1, I resolved problem #2 by sending my cluster over to Relentless Motorsports in Dallas, TX, whom is local to me and does cluster and ECU rebuilds. He is a one man operation who meticulously replaces every chip, resistor, capacitor, and electronic component on the PCB's on a wide variety of classic and modern cars. His specialty is Lexus and Toyota, but he came highly recommended by Erik of U.P.garage since he does the rebuilds for them on GTR clusters.  For those that don't know, on R32 and R33 GTR gearboxes, the speedometer sensor is mounted in the transfer case and is purely an analog mini "generator" (opposite of an alternator essentially). Based on the speed the sensor spins it generates an AC sine wave voltage up to 5V, and sends that via two wires up to the cluster which then interprets it via the speedometer dial. The signal does NOT go to the ECU first, the wiring goes to the cluster first then the ECU after (or so I'm told).  Problems/Roadblocks I first removed the part from the car on the underside of the transfer case (drain your transfer case fluid/ATF first, guess who found out that the hard way?), and noted the transfer case fluid was EXTREMELY black, most likely never changed on my car. When attempting to turn the gears it felt extremely gritty, as if shttps://imgur.com/6TQCG3xomething was binding the shaft from rotating properly. After having to reflow the solder on my AFM sensors based on another SAU guide here, I attempted to disassemble the silicone seal on the back of the sensor to see what happened inside the sensor; turns out, it basically disintegrated itself. Wonderful. Not only had the electrical components destroyed themselves, the magnetic portion on what I thought was on the shaft also chipped and was broken. Solution So solution: find a spare part right? Wrong. Nissan has long discontinued the proper sensor part number 32702-21U19, and it is no longer obtainable either through Nissan NSA or Nissan Japan. I was SOL without proper speed or mileage readings unless I figured out a way to replace this sensor. After tons of Googling and searching on SAU, I found that there IS however a sensor that looks almost exactly like the R33/260RS one: a sensor meant for the R33/R34 GTT and GTS-T with the 5 speed manual. The part number was 25010-21U00, and the body, plug, and shaft all looked exactly the same. The gear was different at the end, but knowing the sensor's gear is held on with a circlip, I figured I could just order the part and swap the gears. Cue me ordering a new part from JustJap down in Kirrawee, NSW, then waiting almost 3 weeks for shipping and customs clearing. The part finally arrives and what did I find? The freaking shaft lengths don't match. $&%* I discussed with Erik how to proceed, and figuring that I basically destroyed the sensor trying to get the shaft out of the damaged sensor from my car. we deemed it too dangerous to try and attempt to swap shafts to the correct length. I had to find a local CNC machinist to help me cut and notch down the shaft. After tons of frantic calling on a Friday afternoon, I managed to get hold of someone and he said he'd be able to do it over half a week. I sent him photos and had him take measurements to match not only the correct length and notch fitment, but also a groove to machine out to hold the retentive circlip. And the end result? *chef's kiss* Perfect. Since I didn't have pliers with me when I picked up the items, I tested the old gear and circlip on. Perfect fit. After that it was simply swapping out the plug bracket to the new sensor, mount it on the transfer case, refill with ATF/Nissan Matic Fluid D, then test out function. Thankfully with the rebuilt cluster and the new sensor, both the speedometer and odometer and now working properly!   And there you have it. About 5-6 weeks of headaches wrapped up in a 15 minute photo essay. As I was told it is rare for sensors of this generation to die so dramatically, but you never know what could go wrong with a 25+ year old car. I HOPE that no one else has to go through this problem like I did, so with my take on a solution I hope it helps others who may encounter this issue in the future. For the TL;DR: 1) Sensor breaks. 2) Find a replacement GTT/GTS-T sensor. 3) Find a CNC machinist to have you cut it down to proper specs. 4) Reinstall then pray to the JDM gods.   Hope this guide/story helps anyone else encountering this problem!
    • perhaps i should have mentioned, I plugged the unit in before i handed over to the electronics repair shop to see what damaged had been caused and the unit worked (ac controls, rear demister etc) bar the lights behind the lcd. i would assume that the diode was only to control lighting and didnt harm anything else i got the unit back from the electronics repair shop and all is well (to a point). The lights are back on and ac controls are working. im still paranoid as i beleive the repairer just put in any zener diode he could find and admitted asking chatgpt if its compatible   i do however have another issue... sometimes when i turn the ignition on, the climate control unit now goes through a diagnostics procedure which normally occurs when you disconnect and reconnect but this may be due to the below   to top everything off, and feel free to shoot me as im just about to do it myself anyway, while i was checking the newly repaired board by plugging in the climate control unit bare without the housing, i believe i may have shorted it on the headunit surround. Climate control unit still works but now the keyless entry doesnt work along with the dome light not turning on when you open the door. to add to this tricky situation, when you start the car and remove the key ( i have a turbo timer so car remains on) the keyless entry works. the dome light also works when you switch to the on position. fuses were checked and all ok ive deduced that the short somehow has messed with the smart entry control module as that is what controls the keyless entry and dome light on door opening   you guys wouldnt happen to have any experience with that topic lmao... im only laughing as its all i can do right now my self diagnosed adhd always gets me in a situation as i have no patience and want to get everything done in shortest amount of time as possible often ignoring crucial steps such as disconnecting battery when stuffing around with electronics or even placing a simple rag over the metallic headunit surround when placing a live pcb board on top of it   FML
    • Bit of a pity we don't have good images of the back/front of the PCB ~ that said, I found a YT vid of a teardown to replace dicky clock switches, and got enough of a glimpse to realize this PCB is the front-end to a connected to what I'll call PCBA, and as such this is all digital on this PCB..ergo, battery voltage probably doesn't make an appearance here ; that is, I'd expect them to do something on PCBA wrt power conditioning for the adjustment/display/switch PCB.... ....given what's transpired..ie; some permutation of 12vdc on a 5vdc with or without correct polarity...would explain why the zener said "no" and exploded. The transistor Q5 (M33) is likely to be a digital switching transistor...that is, package has builtin bias resistors to ensure it saturates as soon as base threshold voltage is reached (minimal rise/fall time)....and wrt the question 'what else could've fried?' ....well, I know there's an MCU on this board (display, I/O at a guess), and you hope they isolated it from this scenario...I got my crayons out, it looks a bit like this...   ...not a lot to see, or rather, everything you'd like to see disappears down a via to the other side...base drive for the transistor comes from somewhere else, what this transistor is switching is somewhere else...but the zener circuit is exclusive to all this ~ it's providing a set voltage (current limited by the 1K3 resistor R19)...and disappears somewhere else down the via I marked V out ; if the errant voltage 'jumped' the diode in the millisecond before it exploded, whatever that V out via feeds may have seen a spike... ....I'll just imagine that Q5 was switched off at the time, thus no damage should've been done....but whatever that zener feeds has to be checked... HTH
×
×
  • Create New...