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351 build help, straight LPG/ mabey turbo

6K views 16 replies 3 participants last post by  ZK 351 
G
#1 ·
#2 ·
Straight LPG!

Never get tired of seeing that. I can suggest a couple of things...

A roller cam is nice but expect to pay a small fortune ($1500+) to get the cam and lifters only. Depending on how hot you want the engine to be you may be better off just going a solid flat tappet or even a big hydraulic FT. LPG only engines typically need 10% more fuel (bigger cam) to make the same amount of power as a compareable petrol engine. But as a plus, LPG idles better, so the difference is minimal.

Single plane intake manifolds are a much better choice for LPG engines that are going to be running a dual gas research setup. Dual plane will most likely run out of puff at high RPM where a single plain (my favourite is a weiand x cellerator) will keep on going. I'd be going for the dual throttle body, dual converter setup. If nothing else it'll give you room to improve before you start running out of fuel.

I'd also suggest you choose NA or Turbo long before you start building. If you choose the turbo route then your piston choice is clearly going to be different, but your heads will be too. Without too much knowledge of twin turbo clevelands, i'd say 4v heads would be the better choice. Only because 4v's aren't going to have flow problems with 20psi of boost being crammed down their throats.

All 4v's should need is a cleanup and their done. Instead your focus would need to be on making the bottom end bulletproof and of course making sure your drivetrain can handle the power!

Good luck,
Greg
 
#3 ·
How much power do you want and at what price limit? What diff (bw or 9") and trans (FMX or C4) are you running?

Talk to a couple of engine builders/tuners as to what they would suggest. Jakes Performance, Dyno Tune, Gas Tune are possible suggestions in the ACT region.
 
G
#5 ·
well not sure what i can get for what i want to pay, only want to put about $4-5k into it though, so roller cam would be out then, it will be daily driven still,
i can get most things done at good prices as well, so that is a helping factor.

has a FMX, its in good order,

has the b/w, 4 pinion LSD with 28 spline axles, i think with the auto this will last a while, i have a few 9" ones to choose from if this one dies... 2.77 ratio, (i know its not the best ratio for go go, but i do long distances a fair bit)

I want to run straight gas just because i have read a few books on it and i like the sound of it, and it gives me more of an option for a big block or even an older clevo block if i want down the track, and have already forked out the cost for dual fuel and would rather just ditch the fuel that cost nothing to put on than the gas that did cost me if you know what i mean, its easier to go back to fuel later on if i feel so inclined to do so,
and i have heard good things about the gasresearch setups.... so yeah..
 
G
#7 ·
yeah well probaby should scratch the turbo idea, was just a thought, i would splash a few more sheckles towards it but i dont really need it if you know what i mean..... good upgrade later on when i want more power i guess

the plan is to pull the one thats in there and rebuild it (and temp fit a 302 or something because i drive it to work every day), but if i can get a cheap black 351 to start on, thats an option also, either way, i mean if i could get a block that had already been freshly bored and an original black block crank (4mab) that had been ground and stuff that would be a bonus, but yeah.
 
#10 ·
I'd agree with xbgs351, a torquey 351 will be way better for your application than a high HP engine.

With the 2.77:1 diff ratio you won't get to enjoy an engine that makes its power above 5500 anyway.

I'd be looking to build and engine that makes a long, flat torque curve and forget about HP. Have a look at the RPM ranges high HP cams operate in. All of them over 3000 rpm. If you were to put a 3500rpm stall converter behind an engine like that, with 2.77:1 gears, you'll go through an auto every month because even at 110kph your converter will still be slipping. If you use a stock stall and 2.77's with a big cam, by the time your engine has made it to its powerband a stock 6cyl will have torqued away and beaten you.

For a more torquey engine i'd try to have the cam kick in between 1800-2000 rpm so you can run your stock stall converter or even a 2000 rpm stallie. Personally i'd go for wade cams grind 750. Don't bother with a dual gas research setup, it won't be needed for this engine. In fact it'd probably run worse than if you ran a single carb gas research setup or an impco 425. I say this because the dual carby setup is worth over $2500 new. Get the heads cleaned up, stainless valves, unleaded valve seats and don't bother with 4v valves, they'll cost you power down low. Aim for a 10:1 comp ratio, LPG being a 98+ron fuel means decent compression is not going to cause problems.

I'd still be inclined to go for a weiand x-cellerator, but an edelbrock performer rpm would also be an excellent match. A reco'd and recurved bosh electronic dizzy with 8.0mm leads and a bosh coil would do for ignition.

A totally stock 4mab setup with a freshen up would handle this type of running, forever.

I'm sure this isn't what you wanted to read, but a big HP engine and the budget you have put up is not likely to happen. Even with more money you'll still need a high stall, shift kitted c4/c10/c6 and 3.9:1 or shorter gears and totally defeated the purpose of a daily driver.

A good torquey engine that can slaughter a hsv with 2.77 gears and a stock stallie, but still get 400+kms to a tank of LPG, now thats a true daily driver clevo!
 
G
#11 ·
well that insnt against what i wanted to hear :) i know if i wanted a high HP beast i would have to spend at least $8k (on engine alone) and not be able to drive it every day :( that would be sad to me... all that $$ spent and not being able to enjoy it every day...

hmm i only get about 250 to 300km out of a tank of gas anyway, out of 60-65 litres (only currently got a 80L tank fitted, although i know i can fit a 100L but just dont have one)

well anyway i like the sound of what you have put forward. sounds like just what i would be happy with.

i sit on about 2300 to 2500rpm at 110 so i would go for the 2000stall option, is it still ok to drive it around town in top though? like when you are doing 80km odd doing bugger all RPM??i guess even the stock convertor would be slipping anyway hey?

so for what you mentioned above i wouldnt be up for many $$ would i? would a set of closed chamber heads be good? as i can get a set that already have been done up for LPG, stainless valves, hardened seats, good springs etc.. only a few thousand km work.. or would that bump the compression too high??

yeah well ok, so you thing the stock rods/pistons will be fine also then?

what are the prices on an impco 425 mixer? and where to get one? actually i am unsure of which mixer is already hanging off it, think its an impco, been a while since i last looked at it.
 
#12 ·
With a properly built engine suited to straight LPG your fuel economy will (should) increase over the dual fuel setup (depending on how your right foot acts)!

The heads you've mentioned sound very good, if you can pick them up at a good price then I would go for it. Then have the combustion chambers opened up and de-shrouded to lower compression.... which actually improves the flow with closed chamber heads, just as a bonus. I personally reccomend roller rockers on any decent engine but there are plenty of people who disagree. Your choice on that one!

A 2000rpm converter would be right on the money for that cam, would give you excellent pickup when taking off and working through traffic too.
Standard 351 bottom end would not have a problem with this setup.
Impco 425 mixer is around $400 new, but you should be able to pick up a good second hand one for around $150-200, even less in some cases!

Now if your looking to get a bit more go, which it seems you are, then just ponder this:
Upgrade to a 3.23 or a 3.45 (borg warner ratios) or a similar 9" ratio.
Bump the stall speed up to 2500
Go for the wadecams grind 869 or similar and get some anti-pump up lifters too.
Everything else as above, including the bottom end setup. Though I would go for the x-cellerator.

A 3.45:1 diff gears will give you waaay more off the line, only bump your 110kph cruise RPM up to 3000 or so. The 2500 rpm stallie will still be OK traffic and when you hold the boot in you should be making power all the way to 6000rpm and get there a hell of a lot faster than with 2.77's.

With every engine/drivetrain there is a compromise. There isn't any way around that. The best thing to do is work out how much your willing to compromise and what you can live with. Many people on these forums drive with 3.45 and shorter gears and don't have problems. My 351 has 4.11's and it'll happily cruise at 110, close to 3600rpm, and because i'm only just touching the throttle it barely uses any fuel at all.

Even my 6cyl daily driver has a 2500 stallie and 3.45 gears... although it runs fuel and the carbie is far to big, I still get 350kms to a tank of PULP. No overheating @110 even on stinking hot days either.

Hope this helps,

Greg
 
G
#13 ·
well i do have a 3:1 9" LSD that i could put in, but would rather not put it in unless i start breaking Bw's, but its an option, i really wouldnt want to go much more than the 3:1, but i guess if i found a cheap 3.23 i would try it out, u know of any?? or the rough prices they go for? can i get a 3.23 center that has the 28 spline axles so i can just put it in the housing i have?? (i know you can change them, its just the question of weather i can get a 28 spline one)

its all sounding pretty good to me so far,

so at what kind of cost can i expect to pay for all this??
its more or less
Cam+lifters?? (new pushrods as welli guess)
New mixer+convertor, up to say 2-400?
heads, possibly quite cheap, will ring the guy later.
intake?? dont know what they are worth
dizzy recurve? $100-150 for memory

bottom end work
grind/balance?? $$
probably wont need to be bored, its only done 50,000 odd km since it was put in, was a reco replacement from what i was told.. my whole car has only done 170,000 odd km anyway...

um, roller rockers, $500odd

standard sump?
still go for an oil restrictor kit?

2000 to 2500 stallie??$

i can do all assembly myself, so that will save some costs i guess,

good tune up?$ dyno tune, and where is a good place in the ACT for that
 
#14 ·
I would put in the 9" and get a new 3.25:1 ring and pinion from VPW for $300, only because I hate BW's.

Cost for the cam/lifters/pushrods? I would speak to the cam makers directly. Wadecams are at www.wadecams.com, any other brand is of course up to you.
New mixer/converter? New, expect $700 or so, second hand you should be able to get them much cheaper.
Manifold - Weiand x-cellerator from VPW: $570, Edelbrock performer $430.
Dizzy? Some places charge completely ridiculos prices (ie $400), my local bloke charged $175 to make my mutant late/early combination dizzy and regraph it.
Crank regrind/balance: couldn't say.... i'd suggest to ring around.
Rockers: Yella Terra Street $560, adjustable $650
Sump is up to you, I wouldn't bother with a restrictor kit.

The 2500rpm stall converter for the XF was made by TCE in Ringwood Vic.... I would strongly reccomend them over dominator. Call them for a price once you have settled on the cam, diff ratio and the stall speed you want.

So, say you get the new diff gears, new gas equipment, adjustable rockers, dizzy reaph recurve for $175 and x-cellerator manifold thats about $2400.

So with the $2600 left (if your budget is $5000) you should be able to get crank, cam, heads, bearings, gaskets and stallie. If you shop around and drive a hard bargain you could save at least $700-800 on the prices i've listed.

Doing the assembly yourself will have this whole thing on the road under $5000 i reckon. No idea on ACT tuners though... i'm from vic.

Cheers,
Greg
 
G
#15 ·
yeah i meant 2nd hand mixer convertor,
i know a guy that knows a bloke that i can get a dizzy done for $100-$120 for me.
and have a good mate that can buy most every new part at trade prices where available, so that should help my finances even more

i do actually have a stage 3 C4 with a 2500rpm stall, but after getting it decided not to put it in, i like the strength and reliability of the FMX, i keep hearing too many stories of people blowing up C4's, lol

why wouldnt you bother with a restrictor kit? are they mainly for high revving hot engines or??

oh and should i bother with fitting 4 bolt mains or not?
 
#16 ·
Mate I would use the C4 and stallie over the FMX any day of the week. FMX's are fine behind standard engines but tend to die fairly quickly with any serious power going through them. Some of them are abnormally strong but its hard to tell. I've actually seen one explode on a dyno, never seen a C4 do that! Just keep the FMX and put it back under the car if the C4 can't take the power.... but I seriously doubt it'll have a problem.

What LPG converter do you have at the moment? it may not need upgrading. As far as the impco 425, you'll have to look around. I can't give any prices because I havn't looked for one in a while.

Restrictor kits and 4 bolt mains are only needed in hot clevos, I really wouldn't bother with either unless your doing high RPM drag racing. Ford main caps are very strong from the factory.

I saw a kit today that might be of interest.... also from VPW: Only $840 for a 351C, not a bad price at all if you ask me. Part no is EKA-351C

"Our best engine kit with premium Keith Black pistons (hypereutectic) and moly rings, premium cast pistons with moly or cast regular rings. You also get Michigan main, cam and rod bearings, a Mellings high volume oil pump, top quality Fel-Pro gaskets, a set of oil and freeze plugs, and assembly lube to finish the job."

There are cheaper kits, but i'd spend the extra $150 and get this one.
 
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