ivtriedeveryusername

Hi everyone.
New to this forum and heaps of questions.
Im a previous driver of many Valiants, all sixes, a few VG pacers, VH and VJ regals.
This is partly the reason for picking the 318 engine. As well as the price.

The engine is to be fitted to a Mazda T4100 truck. The truck will be used as a car carrier (4 cars) and tow truck (lift on the rear to tow other trucks). Over the past few months I have been modifing the truck, lengthened and widened the chassis where the engine will go, second deck fitted above the cab and a 2 car trailer is nearly finnished.

The original 4L diesel is gone, I was looking for a 351 Cleveland to power it along, but this 318 came up for the right price, and is now going to be the powerplant.
The original 10speed gearbox is being used and an addaptor is being made.

All up the truck will be pulling nearly 10 ton fully loaded.

Reliability is a must, the engine will be running straight gas.
The motor was sourced from a dodge truck, not a truck motor as far as I can tell as it has a edelbrock inlet manifold, the truck motors had a 4 bolt main, different heads and noone makes aftermarket manifolds for them.

Now for the question
How do I make the maximum torque from this engine? HP isnt a factor as it wont be reving over around the 5K mark ever. It will be doing 2,400RPM at 100kph.

Any ideas or tips would be greatly appriciated.

BossHoggett

Different heads ?? Maybe Magnum ?

First thing i would advise is the Flywheel, this needs to be heavier, as youll need the engine momentum, this is critical. it gives the feeling that a larger engine would give you in Torque....Try Dellow Automotive or Castlemaine Rod shop.... dont know today havent done one in 20 years, or a machinist can make one too ?? whatever.

2 biggest things id look at are camshaft choise and compression but dont scrimp on the ignition either, you still have to burn fuel to make power.

Camshaft is small small small.... and keep your lobe centres closer to 108 if you can. this will give a very narrow powerband but give you a very good vacumme off idle and promotes high torque....if it runs out of puff at 4000-4300 that will give maximum torque then around 2000-2400 so youll get good milage around 80ks.
Mostly youll find available cams are around 110-112 so youll be looking around as brocures and written material is aimed moreso at the 340 and 360 engines.
112 centres are a better choise in a larger engine, as it fattens the torque curve a little, but with 10 speed box and your opperating RPM range your not interested in a torque spread, thats what gears a for.

The other thing is LPG is wonderfull stuff, it come out freezing cold and cools your combustion chambers reducing the tendancy to Pre-ignite. or ping or rattle. so you can give the engine unbelievable amount of compression before it does. so with some decent hypereutectic pistons and 11.0:1 compression and honestly i would be suprised with a combustion chamber polish it went more but they have 4 head bolts per cylinder so gasket seal becomes an issue after... if you have a head with 6 and the blocks been modified to suit your a lucky man other than that O ring the block or heads to keep the gas in . If you want to run it on AVGAS as well for that extra torque for hill climbs (year right) it will take to it like a duck to water, but forget pump fuel..

Also im guessing that youll be needing custom exhausts.... yea you can use standard... but i cant tell you enough that thats a poor choice. Rule of the thumb, The longer your primarys are the greater the emphisis on torque production lower in the RPM range. and since your looking for 2000 as around maximum. Then id be making them 4 foot before entering into a collector.

I balance all motors, they just run smoother regardless of what its for.

Then youll have a 318 litre that will pull a house down. or go from a 3.310' inch stroke to the 360 3.580' crank for a cubic inch of 344 (youll need the small journal 360 crank) and rebore the block from 3.910 to 4 inch and its a 360.. Also remove the 318 windage tray when useing the 360 crankshaft. also use Full grove main bearings.

VAN454

A blower? lol other than that, the above advise is very sound, but I wouldn't expect it to be a huge issue, they are pretty torquey to begin with, then you put a 10 speed behind it, it should climb the side of a mountain..........just maybe kind of slowly

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Cougar

I'd argue against high compression in a heavy vehicle. Can't quite remember the reasoning right now, but something to do with pinging when lifting off the accelerator for example on a down-hill. I think there was more to it as well. My dad's a mechanic with 30+ years experience, and he (along with his engine-builder) decided on a maximum of 9.5:1 compression when building an LPG-powered 460 for his bus/motorhome. I think we ended up at around 9.3:1 when we built it, and it certainly pulls well, although it likes a drink, never been able to get better than 2.5km/litre, no matter how gently it's driven, and if you give it a bit, it's worse than 2km/litre.

ivtriedeveryusername

Thanks for the tips.
Pulled the engine down and some bad news, the heads have coroded away to dangerously thin thicknesses, the engine will need a complete rebuild, which equates to lots of $ which I dont have at present. So have decided against using this engine.
I am on the look out for a 351 again! There are some advantages in using the 351, more power and torque, an adaptor is now available for it and availability of parts.
I will take on board all the advice and ask the question on the ford v8 forum.
Thanks.

BossHoggett

351's arent the engine for torque. unless your going to opperate in the higher rpms. a 350 chev is better choise. and so would the 360 Chrysler.

allports

Flywheels making torque????? What tha. how so when they are outside the powerplant?
Newtons 1st law for every force there's an opposite and opposing force or for every action there's and equal and an opposing reaction.
Now if your talking kinetic energy that's different again, he'll need to be able to turn this large flywheel and if it takes effort to turn it, then it will take fuel to turn it as well. Albeit once its up there it will be able to remain spinning easier, but you gotta get it there 1st. And remember you've told him to choke it back with a small small small cam and a narrow lobe centre will give you less vac due to the higher lift @ TDC so actually spreading the lobe centre out to 112-114 degree will increase vacuum. A small small small cam will be the best way to limit everything.
Now correct me if Im wrong here but isnt passing CFM of air through the engine the whole reason of making torque?
tsk tsk tsk.

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BossHoggett

Larger / heavier flywheels carry momentum, to break rolling resistance and help to maintain momentum on road. I considered the lobe centre argument and went for the tighter centres due to the narrower opperating range. so idle vacume isnt a consideration nor is top end horsepower. its the peak torque band that is in interest in a towing vehicle with 10 speeds. if it was a power glide transmission then the importance of 114 centres to promote a wide torque band with good idle and fuel economy i would have said so. and as i also stated most literature for Chrysler small blocks are aimed at 340 to 360 engines, not 286s or 318s so the dynamics of a camshaft designed for a larger displacement that promotes a balance will typically be more aggressive in a smaller engine.

CK_318

not normally one to nit pick here, but i have to this time.

i'm sure you meant 273 not 286.

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BossHoggett

hahah yea

allports

29/06/08 9.42am "Camshaft is small small small.... and keep your lobe centres closer to 108 if you can. this will give a very narrow powerband but give you a very good vacumme off idle and promotes high torque...."

12/07/08 7.51pm "so idle vacume isnt a consideration nor is top end horsepower."

So which one is it? Is or isnt. I would suggest that you should actually try what your suggesting him to do! Have you done it before??????? Your results may not be as you surmise. Im speaking from exp here. And who in their right mind would use a wheezy 318 for pulling big weight successfully anyway? Like hello A 400 Chev, Clevo, Mopar but a 318 pfftt. If your talking small blocks.
LPG ay ok then but a tighter lobe centre, you should know that an engine put on LPG will lose torque with that lobe centre!

__________________
If you plant a cucumber, you get a cucumber!
Two things are infinate,the universe & human stupidity, and Im not sure about the universe.
Albert Einstein
Without deviation from the norm, progress is not possible. Frank Zappa

Cougar

I don't think a 351 would be lacking in torque for the job. My dad put one in his old Landrover. We gave it a hard time, such as towing a trailer with another Landrover on it, and parts for two more complete Landrovers stacked wherever they'd fit on the trailer and in the tub. (We'd bought a Landrover wreckers, and were transferring all the stock). It'd pull hard enough to wrinkle the rear tyres dragster style when climbing hills, and was still overtaking Isuzu's and the like on the hills.