Running at 2700 rpm
Hi again. My apologies as this is sort of a repost, but I figured if I asked the question a different way, someone might be able to help me.
I want to put a 3.8 ecotec motor in a small bus, (A Toyota Coaster) and based on the diff and gearbox ratios I would end up with the engine turning over at 2700 rpm at 100km/h.
The drag and windage of the bus are about the same as a large 4WD.
Do cuurent owners of this sort of engine think that is too high?
Help.
Matthew
I think that that is going to be reving to high.Maybe look into getting higher ratio diff gears.You would probably want it to rev around 2000- 2200 revs @100km/h.You wouldnt want to go too high with the gearing though otherwise it will struggle to pull it along.
Hmmm, I feared that. Unfortunately that is the highest ratio availalbe to the bus without doing a seriously expensive diff conversion.
What gearbox are you going to use.
Bloody Richo
dude ask dellows conversions in sydney they do some amazing things for not that much. they propably have done something like this and can mix and match gearboxs cheaply with your engine.
Making and running DUAL CHIPPED ECU SINCE 2010
"..of mice and men.."
Yeah you're looking at 'around' 2000rpm@100km/h, and 'around' 2500rpm@120 in an average V6/auto commodore, that's basically using minimum throttle to hold speed.
On the 7th day, God created Holden, then on the 8th day, God created Ford, to keep idiots out of Holden's.
Originally Posted by destiny
I was going to stick with either the TR5 or the auto that comes with the car. I'll ring Dellows and see if they've got any ideas, but it sounds like I'd either have to find a gearbox with some insane overdrive ratio (0.6:1) or put a stepup on the back of the box. Messy. The whole advantage of the commodore conversion is keeping it simple so if it breaks something in outback Oz I can get the parts.
At the moment the other option is the old 3.0 litre Nissan donk from the VN(?) I think. It has a good rep and according those who know it would like those sorts of revs.
"..of mice and men.."
The Nissan 3.0 is from the VL, and sits at 'roughly' the same revs in a commy as the V6 does at 100km/h.
On the 7th day, God created Holden, then on the 8th day, God created Ford, to keep idiots out of Holden's.
Maybe try to get hold of a six speed manual box.It should have a high enough overdrive gear to drop the revs a bit.I dont know if one of these boxes can be bolted up to a V6 though.As mentioned above,Dellow Automotive specialise in this sort of stuff and would be worth contacting.
"..of mice and men.."
There were 6 speed manual gearbox's that were released with some V6's, from the VN onwards, not as easy to get hold of though..
On the 7th day, God created Holden, then on the 8th day, God created Ford, to keep idiots out of Holden's.
Yes, good point, but apparently it likes the revs, and being smaller, it would probably need them to push the load. I'm told the bottom half of the engine is bullet proof, though the head has to be watched.
Does anyone know the model of this box so I can look up the specs?
"..of mice and men.."
Yeah their bottom ends are pretty tough, only problems you really have to watch with the head is keeping your maintenance up to the oil and cooling system.
They really don't like getting hot at all, but with a good cooling system keeping temps down, and quality oil that's kept clean and changed regularly, they run great.
On the 7th day, God created Holden, then on the 8th day, God created Ford, to keep idiots out of Holden's.
Good advice, thank you. It seems I keep coming back to the 3.0 litre. Pity, the 3.8 would give me a lot more power. I'm just trying to find out more about the 6 speed, but from what I have found so far, it won't help as the ratios are just closer together, and actually, not nearly as tall at the top. They must have run a higher diff ratio instead.Yeah their bottom ends are pretty tough, only problems you really have to watch with the head is keeping your maintenance up to the oil and cooling system.
They really don't like getting hot at all, but with a good cooling system keeping temps down, and quality oil that's kept clean and changed regularly, they run great.
"..of mice and men.."
No worries mate.
Yeah I was having trouble finding info on the 6speed too, but I'm sure there were some as far back as the VN, because a mate used to own a 6speed V6 VN years ago.
On the 7th day, God created Holden, then on the 8th day, God created Ford, to keep idiots out of Holden's.
What the heck, I should just put a rotary in it then the current 6.8:1 diff will be no problem at all. :^)No worries mate.
Yeah I was having trouble finding info on the 6speed too, but I'm sure there were some as far back as the VN, because a mate used to own a 6speed V6 VN years ago.
Donating Member
My opinion for what it's worth is that 2700rpm @ 100kph would just about be right or possibly even a bit low!. Reason is primarily that the Coaster weights 50% more than a Commodore plus has double the wind drag factor. The Ecotec develops max torque of 304Nm @3600rpm - so 2700rpm is much closer to the max figure than 2000rpm. Also if you use a taller gear with 2000rpm @ 100kph, the slightest headwind, rise or truck overtaking will rapidly wash off speed. Another problem would be that you would only be able to cruise on dead level ground at that speed as the slightest rise would again kill the speed plus create one hell of a lot of strain on the gearbox. Most 4WD's that tow, particularly Patrols and Landcruisers advise against towing in 5th for all of the reasons I've mentioned. My Commuter van (recently sold) sat on 3000rpm @ 100kph in 5th and chewed petrol at this speed.
Most if not all commercial vehicles sit around 3000rpm at 100kph (I know there are exceptions) and for a good reason - less strain = longer life.
Good Luck.
"..of mice and men.."
Very good points there hako.
On the 7th day, God created Holden, then on the 8th day, God created Ford, to keep idiots out of Holden's.
OK, I follow the logic about the weight and drag, and it makes good sense.
My mate just emailed me to say he has been driving his VT around at 2700rpm and he reckons it feels fine. Just run that last bit about the van past me again if you would? Are you saying 3000 rpm IS too high, or at least was in the van?
Having that engine in the van would be pretty much equal to towing a large caravan at 100km/h with a commodore. They do that fairly easily.The auto trans has to be cooled well though because of the extra work.
Real cars are steel cars.
I agree with hako. A coaster is a big heavy lump to shift and hold a decent speed. Only problem is the ecotec is far from smooth at 3000 rpm and above so the vehicle may seem as if its working pretty hard at 100kph. The RB30 (VL) motor is silky smooth by comparison but lacks the low end pull needed for this application.
Perhaps a small V8 would work with a taller ratio? Is there any thing else in the Toyota commercial range that runs the same type of diff gears as the coaster. I used to fit V8s to Landcrusers and a 3.7:1 aftermarket (from std 4.11:1) gears worked really well with the V8. Basically an extra gear but still with good pulling ability.
Would a complete diff conversion be an option? May be cheaper than sourcing a replacement gearbox.
If I told you I was a compulsive liar, would you believe me?
Donating Member
The point about the van was probably not properly explained and I suppose not really relevant except to say that Coasters or Commuters are not high speed cruising machines and will chew the fuel no matter what ratios used.
The Holden Handbook (factory) says about towing "some drivers may prefer to select "3" position in "power" or "economy" modes when towing. This will raise the speed of the engine at 100kph to about 2500-2700rpm.
If I were doing such a conversion I'd use the Toyota gearbox and diff as-is otherwise there are too many hassles and improbables. Fitting a 6 speed box would cost many many thousands and I'd imagine they are pretty fragile unless designed for commercial vehicles. Good Luck.
Donating Member
Not disagreeing with you Brett, but the factory says if towing a van over 1200kg you must have the following fitted: auto trans, large A/T oil cooler, power steering cooler, body side brace package, superlift shocks, centre bearing heatshield, intermediate muffler heat shield, heavy duty radiator, synthetic oil for diff. Also say "The Holden Handbook (factory) says about towing "some drivers may prefer to select "3" position in "power" or "economy" modes when towing."
I've towed a 17 footer with mine....weighed about 1.2tonne and it felt like I was towing an anchor. Needed 2 feet for the brakes most times (mechanical on van NBG) I had none of the essential factory items listed above....maybe I should have. Vanners seem to prefer Falcons for some reason or other???
Ive also towed cars on trailers with mine,its a V6 but has the towing package with the brace thing in the boot and large trans cooler.I towed a car for 400 km and it did it piss easy,up and down a couple of mountain ranges and all ,the car being towed was an XC V8 falcon.I just left the VS in overdrive,didnt have to worry about changing up and down gears or using lower gears etc.It cruised along fine at 100km/h in top gear,the commodore,the XC plus the trailer would easily weigh a couple of tones or more probably similar to the toyota bus.The whole point im getting to is the engine did it easily and a toyota bus would weigh about the same as the commodore and trailer plus the other car on the trailer.The brakes etc already fitted to the bus would be designed to stop that sort of weight already anyway.The engine that was in it originally probably weighs the same or would be a similar weight anyway to a V6.
Although i do not see anything wrong with 2700rpm @ 100kmh for a small bus, an easy way to reduce the rpm @ 100kph would be to run tyres with a larger profile for the rear.
Never be afraid to try new things; remember amateurs build the ark while professionals build the Titanic.
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