Hi.

I have started a thread in the LPG section with some specific gas questions, but thought I would post one in here as well.

Im looking to fit a 351c 2v closed chamber into a truck, which will be pulling about 10-11 ton. Straight gas.

I have a few questions about making more torque lower in the rev range. So far I have read so many posts about making more power, but this power isnt where I want it. Im looking at trying to make more / maximum torque from around 1000-3000rpm. I never plan on reving it to 5000rpm.

Any ideas? as I dont have a heap of cash at the present and all parts I will be looking for will be second hand, except for a cam. There are a few swap meets around and always cleveland stuff there, but which stuff to buy.

Inlet manifold. From the posts and articals I have read a single plain manifold is best for gas, but do the runner lenghts make a difference with gas as they do with petrol? and if so which manifold would be good for power lower in the rev range?

Exhaust. So far Im on the look out fro a set of extractors, do longer primaries promote torque lower in the rev range? and I have read so many articals about back pressure, some say its needed, others say no, and then there is a heap on cam selection and tuned lenght Vs back pressure.

As for cam selection, nearly every brand sells cams for towing and others for gas, but anyone had experiance with a cam that would be suitable for both? company, grind etc.

Also looking for a straight gas carbie, any reasonably priced ones that would be suitable?

Any help would be apreciated.

Cam- talk to wade, they can make just about anu grind you want, as long as you know what it is you want.

exhaust- long and/or thin primaries are better for low down torque. this is becaue it keeps up exhaust gas velocity at low rpm. getting your headers and even the parts of your exhaust ceramic coated can help keep the gas hot (less heat loss through the pipe) which means less dense and easier to push out hence more torque. either twin 2 inch exhausts or a single 2.5 inch would be the go for low down grunt. a 2.5 with free flow mufflers on it will start to strangle above 3500 rpm id hazard a guess. but below that would be fine.

Get bigger inlet valves and a longer stroke. (if by heaps of cash you mean heaps of cash).

or bolt on a m112 eaton, or whipple supercharger

Compression helps...Esp with gas..

We've got an F-350 with a 351 in it, and just had a GRA setup installed. Made about 120hp at the wheels, but the motor is burning some oil.
I think with a mild cam and a full zorst we'd be pushing around 150rwhp, but thats still a fair way under what you need.

I'd suggest a blower if you need to move 10 ton.

Forced induction is out of the question, this would cost a bomb. It would be nice though.

I have thought about a stroker kit, but reliability is a must and the whole cash thing again.

I got a diff from a t4000, which lowers the revs to 2400rpm at 100kph in 5th, empty Im sure the truck will pull 110kph no worries, but loaded, im hoping for at least 85-90kph in 4th.

From the factory it came with a 4lt 6 diesel and im sure the 351 will out pull this (well kinda sure). The original engine wasnt the best and has gone off to the wreckers.

Our truck is a 5spd and sits on 2k rpm at 100rpm.
It's goal is to tow up to 5 ton. ATM, with a stock motor on gas, it'll pull about 2 ton pretty easy, but any more and it dies in the a** atm.


A 2nd hand blower will be under $2k pretty easily.

I would look at gearing as well. By going lower in the gearing(from say 3.08 to 3.9) you increase the torque multiplication, so you have more torque, plus the advantage of better pulling power off the line. As for the rest i would look at cubes and comp. So 393 stroker with 10.5 comp for gas on a good single plane manifold with long small diameter primaries in a tri y configuaration.
Brett

Have you thought of a M400 motor ??
460 big block ??
Stroke and gearing..
A blower would mean reliability issues..

Towing 11 tons!! Ouch. Honestly I don't like the thought of a Cleveland in that application.

You need that big block XR9UTE had at his work out of an old bus.

Yeah Dave, the 477 or better still the 534.
I'd get a late EFI 460 and run gas through it. But, if you could afford to, get a Scat 557ci stroker kit.

BTW there was some eastern states mob selling brand new EFI 460's for $5500 in the Just parts mag.

2nd Pete's comments.

Trying to make the torque you need to haul around 12tons from second hand Cleveland parts is begging for disaster...

A big block would be nice too. But they cost money which I dont have, also Castlemain rod shop makes an adaptor now for this aplication, with any other motor I would be stuck making my own, not impossible but very time consuming and a bit risky, as if its not exact there is a real chance of the block spliting itself in two.

Also parts wise I need to be able to access spares asap to reduce any down time and there are many, many cleveland parts floating about and not that many big block parts.

Got to remember that by fitting a 351 into it I dont expect to win any land speed records, it just has to be reliable and I want to lower where torque is produced, I know its a big ask for a car engine, but its a big car engine. Modern truck engins arnt this big, they develope loads of torque and can rev like a petrol though. Im confident that the 351 will move it down the road and I can use the split gearbox, effectivly giving me 10 gears, not the 3 or 4 that the 351 originaly cam with.

Any other ideas about increasing torque lower in the rev range?

Stroke it out a bit more?

Actually there are plenty of 460 parts around and they are cheap but if you must go cleveland..... I'd use a Hydraulic roller cam with more than 114 lobe separation, one of those Torque power high rise dual plane intakes, 4-2-1 headers but I would probably use open chamber heads because they actually flow better in stock form than closed chamber jobs just polish the chambers up nice and smooth. I'd use 4V inlet valves but leave 2V in the exhaust side. I would use a Multistrike ignition like a Crane Hi-6 and also probably do at least a 393 stroker but then how many stock parts do you want to use?