Convert 12 valve to 24 valve. Idle musing......

[Lorin]

Just thinking about options.....

I assume it is possible to convert a 12v to a 24v but what is involved other than swapping the head?

I know the fuel pump is also different. Would this require changing the timing bits (technical speak) as well. Would it even be necessary to change the pump....?

I suppose the obvious question is would it even be worth the hassle compared to just doing a full engine swap....?

 

[Roger Fairclough]

Pistons will be different. Cheaper to get a new engine and sell your old one.

Roger

 

[Jon Wildsmith]

Why would you want to? Whatever bits are needed I can't see them being cheap.

 

[Lorin]

Why would you want to? Whatever bits are needed I can't see them being cheap.

It really was just an idle muse..... I was just curious as to what it would involve as I ponder options for getting the 24v I wish I'd got in the first place! I just can't justify getting rid of the current 80 with the rather substantial financial loss it would entail, just to start again with another truck.

 

[Geert]

Why would you go to a 24v?
I've heard that in the 'rally' world they used to swap 24v to 12v because a 12v has less moving parts...

 

[Jon Wildsmith]

what are you trying to gain by getting a 24v though? Wouldn't you be better spending the money on the engine you have?

 

[Lorin]

It's the improved economy the 24v offers that I'd like. Not sure there's any room for improvement with my engine as the injectors and pump have been reconditioned. We're doing a 3500+ mile trip this year and are planning a couple of 5000+ mile trips over the next couple of years. Our 17-20mpg at best hurts a fair bit more than the 25+ mpg the 24v appears to offer. I know it's probably a false economy to consider any sort of engine change, hence why it was just a curious thought....

 

[AndycruiserguyLomas]

Just to add my bit Lorin, I doubt you would get 25+ mpg with a 24V engine with a overland loaded truck, I get around 25 to the gallon in my GS with alloys so its probably the lightest variant, extra weight really knocks the fuel consumption.

Andy

 

[stumog]

If its just the fuel you are trying to improve wht not covert to a manual box. i am getting about 26 on mine with km2 and loaded with 3 longboards on the roof. Does the 24 v have a different auto box in it? If so can you change that or add a overdrive unit?

 

[Rob]

Lorin's 80 is already a manual Stu.

Lorin, when my 80 is loaded up for overlanding I have only ever got 25 mpg or more on a couple of occasions and that was a long, slow and boring drive each time. I don't really bother to check my MPG unless the light is still not on after 400 miles which happens rarely. Now I know my injectors and pump could do with some TLC but that is serious money which you will have to spend on almost any 24v you will buy these days if you want amazing fuel economy. Also take into account the amount of time and effort into getting the 24v baselined and transfer all the nice bits over to your new one.

Just stick with the 12v you have, especially if you have spent the money on injectors and fuel pump. Also the difference in cost of fuel over 20000 miles at £1.4 between 18mpg and 22mpg is £1284. You will have to travel a lot further only to break even on the vehicle purchase price alone.

 

[Jon Wildsmith]

Tyre choice and size of lift will be factors I'm sure but now you've had the pump and injectors rebuilt what about the pump timing, valve clearances, condition of the turbo / boost level and fine tuning of the pump fuel settings? There's probably room for some improvement without spending a fortune, less than an engine swap

 

[Scott]

17-20MPG at best! Ouch. So you get worse when loaded on a trip?

I agree with the others that I think it would be a false economy changing vehicle or engine, but I would be expecting better. If my memory serves me correctly, you have spent a fair bit of time and money making sure that the truck is in good condition, but if it was mine I would be checking everything closely to see if something was causing the poor consumption.

What lift are you running these days? (I know the truck had big lift when you bought it) Lift causes drag and yours seems tall.
You have a bodylift, which compounds the problem.
Is the tent on when your getting 17-20mpg? The traditional style roof tent aren't that aerodynamic.
What size are your tyres? I see that they're muds, when I put my KM2's on with the OEM steels I really notice the difference. There's a lot more mass to rotate (and stop). When I put my alloys and road tyres on, the truck comes alive again and feels like a go cart. Do you have any roads tyres and alloys that you could use to make a comparison?

I hope I'm not stating the obvious to you, but if the truck isn't doing what you want it to do, then it must be worth the effort to adapt it so that it does.

Just an outside thought, does you speedo read correctly/accurately? I know some have used inaccurate speedos before and got artificially poor MPG results.

(Edit - Jon beat me to it!)

 

[Chris]

I dream of 17 mpg

 

[Lorin]

I dream of 17 mpg 

Ahh perspective

You're all right, I know. If I took off the 2" body lift, swapped out the 2.5" suspension lift, went from 33" muds to 31" ATs and took off the tent, it is reasonable to assume mpg would improve.... However, that isn't going to happen

Having already wasted substantial funds doing things that either didn't need doing or added nothing of benefit, I am resolved to NOT repeating my mistakes. It was just an idle thought anyway but engine swap is out and I'm not starting again with a new truck (at least not yet )

Jon, I think I will as you suggest look at getting the valve clearances done and the pump properly set up.

 

[pugwash]

In a similar vein I've often wondered about the difficulty of converting it to common rail diesel injection. There are now aftermarket diesel ECU kits, and Diesel injectors are easy to find- you could strip the parts from any 6cyl diesel bmw or merc passenger car.

At the same time you get also fit a pair of Variable nozzle turbos- you'd probably end up with 350bhp!

marine spec engines with exactly the same block and piston can be bought at 360bhp!

 

[Towpack]

marine spec engines with exactly the same block and piston can be bought at 360bhp!

I guess you're talking about the Yanmar variant which is essentially a marinised 1HD-FT. The problem with extracting this much power for a land based application would be cooling, not a problem in a boat of course!

 

[IRLGW]

It's the improved economy the 24v offers that I'd like.

Not sure where you get that from. My 12v does 29mpg all day long and it has 200k on the clock with 265/85/16. The brochure from 1993 quotes the manual as offering 31mpg. I would have thought that under normal driving that a 12v would use less than a 24v, although under load or acceleration the 24v would be more economical. Max torque for a 12v is at 1400rpm but for a 24v is at 2100-2200rpm so the 24v will have to be worked harder in some situations. I think a lot of people think 24v are much superior but the gains are marginal other than the truck is generally going to be newer......just my 2c

 

[Towpack]

The advantage of a mutlivalve configuration (and the reason for moving to such a setup) over a simple 2 valve setup is better gas flow which, ultimately means more power & torque due to the greater efficiency of the cylinder head. In the case of the 1HD-T vs FT, the FT does produce it's max torque figure (in 'standard tune') at higher revs but it has more of it, plus, will ultimately give more power/torque if you go down the tuning route. The lowdown torque of the FT from just off tickover can be greatly improved by the well documented pump tweaks which will match or even better the figure of the 12v IMO. Manual box as opposed to auto and driving style will be the two biggest influencing factors which dictate economy but, all things being equal, the 24 valve will be more economical due to the greater efficiency of the engine. Whether or not the difference would be noticeable in real world, every day driving is questionable. Personally, if I owned a good, well running 12v, on which I'd spent ££££ 'personalising', I wouldn't be bothered about swapping it for a 24v model. JMO

 

[IRLGW]

The advantage of a mutlivalve configuration (and the reason for moving to such a setup) over a simple 2 valve setup is better gas flow which, ultimately means more power & torque due to the greater efficiency of the cylinder head. In the case of the 1HD-T vs FT, the FT does produce it's max torque figure (in 'standard tune') at higher revs but it has more of it, plus, will ultimately give more power/torque if you go down the tuning route. The lowdown torque of the FT from just off tickover can be greatly improved by the well documented pump tweaks which will match or even better the figure of the 12v IMO. Manual box as opposed to auto and driving style will be the two biggest influencing factors which dictate economy but, all things being equal, the 24 valve will be more economical due to the greater efficiency of the engine. Whether or not the difference would be noticeable in real world, every day driving is questionable. Personally, if I owned a good, well running 12v, on which I'd spent ££££ 'personalising', I wouldn't be bothered about swapping it for a 24v model. JMO

Agree Totally.

 

[Ian Rubie]

One of the best back to back comparisons I have done was a trip to Libya with Toby. He was in a 12v auto and I was in a 24v manual. We had very similar loads and were running identical tyres. Because we were travelling together we were obviously going similar speeds and distance. Over the 3 week trip the 24v manual used 10% less fuel than the 12v auto. The gap would have been smaller, in my opinion, if the 12v was a manual.

Ian