best comp engine

[zardos]

V8 petrol (3.9) -

less gear changes just use the right foot for more revs (about 1.5 times the speed range in the same gear compared to a diesel, so it has some advantages of an auto)

instant response (no turbo lag)

Nice sound

Manual gearbox with underdrive (just practice the 1st -> 5th)

[Hamish Grundy]

3.9 cams are different, it depends if you're counting the cam as being part of the 3.5 block or the 3.9 top end you were going to use really. The 3.9 heads are a different part number, as are the 3.9 exhaust valves (inlet are the same), but exactly how much better that is I've no idea. The heads are the same casting and frankly I doubt there's much in it that would warrant the hassle of swapping.

i was planning on using 3.9 cam, heads and injection on my 3.5 block, as i have a 3.5 that needs a top end rebiuld, and a 3.9 with a porous block so it wouldnt involve much hassle realy as the engines are both out o vechicles so should be a nut and bolt job......i hope!!

[timmymac]

hi all thanks very much for all the replies but still i dont feel there has been many replies saying use this because so could i change the original question to

for a challenge vehicle

what engine/ gearbox setup are people currently using or have used, and found suits them and if you could explain why?

if it helps i like the idea of 3.9 v8 , auto with megasquirt (maybe! so any feed back on this setup would be great) good or bad

thanks again tim

[Dave W]

hi all thanks very much for all the replies but still i dont feel there has been many replies saying use this because so could i change the original question to

for a challenge vehicle

what engine/ gearbox setup are people currently using or have used, and found suits them and if you could explain why?

if it helps i like the idea of 3.9 v8 , auto with megasquirt (maybe! so any feed back on this setup would be great) good or bad

thanks again tim

I've run a 3.9 auto in challenges for about 8 years before switching to my current setup. It's a very good all round package, nice and easy to drive and performs really well. Prior to that I was running a 3.5 auto for trialling and that was also a good setup but, being on carbs, was slower to respond and not as reliable on steep inclines.

In 2004 I 'squirted the 3.9 and never had a problem with water since - just don't forget you now need a snorkel !

It's been a good reliable package other than requiring a recon gearbox in 2006.

I've run both the viscous transfer box and the LT230 in various ratios. The 1.2 of the viscous is a bit high geared for the setup when you go up to larger wheel sizes and at 35" or above the 1.6 transfer box is preferable, especially if you're doing any motorway mileage.

The LS1 package is much better but it's in a different league money wise too.

[A Twig]

2.25 Diesel is the only sensible option, if you run the numbers:

Cost to buy: £0

Reliability: Good

MPG: Good (and you can run on veg oil, margarine, mud, sticks, etc.)

Choice of gearbox: Anything LR 4-pot

Likelihood of breaking drivetrain components: 0

Likelihood of speeding ticket: 0

Ease of maintenance: Good

Cost of parts: Very low

Insurance: Cheap

On the BHP/£ calculations it achieves approximately infinite value, which is pretty hard to beat. It loses out on the BHP/Kg a tad but the rest of the numbers are strong.

I just snorted coke out my nose in the middle of a library

[rope runner]

2.25 Diesel is the only sensible option, if you run the numbers:

Cost to buy: £0

Reliability: Good

MPG: Good (and you can run on veg oil, margarine, mud, sticks, etc.)

Choice of gearbox: Anything LR 4-pot

Likelihood of breaking drivetrain components: 0

Likelihood of speeding ticket: 0

Ease of maintenance: Good

Cost of parts: Very low

Insurance: Cheap

On the BHP/£ calculations it achieves approximately infinite value, which is pretty hard to beat. It loses out on the BHP/Kg a tad but the rest of the numbers are strong.

[/u special stages are done with a stopwatch though not a calender !

[Shaunus]

I do winch challenging and Auto is the way to go, a few years ago I was the only one in 4x4 Adventures challenges with Auto but now more and more are changing from Manual to Auto. There is a lack of engine braking but the big pedle sorts that out or use your rear winch.

My challenge 90 truck has a V8 3.5 with 3.9 top and sounds sweet with plenty of grunt, I also have another project with a V8 3.5 manual, but you can feel the difference with 3.9 top and is much better.

Having said all that I'm "selling" my challenge 90 truck with 3.9 top which won the Strd+1 series with 4x4 Adventures 2008 and with my new project removing the V8 manual and replacing it with 300 Tdi Auto, this should sort out the bogg sectoins.

[tblandy]

Challenge trucks ive had:

2 door bobtail 100" 3.5 v8 manual

1994 defender 90 300tdi (tweaked pump and boost, straight through zaust) Manual

200tdi 100" r380 box (Tweaked pump and boost, no intercooler, straight through)

1998 300 Tdi Auto defender 90 (Tweaked pump and boost, BIG intercooler, Stainless with 1 smallbox)

And current 300 TDI defender 90 Auto (tweaked pump and boost, straight through zaust)

AUTO IS THE BEST ALL ROUND! Any whos used an auto for any amount of time wouldnt have a manual if the choice was there!

As for v8's why??? there ****e in water, are getting rarer and harder to replace with a good one, they expensive to run, they all boil at some stage!!!

The 300tdi is cheap to replace, full discos come at £500 and there bullet proof!

In CHALLENGES YOU NEVER WANT MORE POWER. ONLY MORE TRACTIION!!!

Anyways just my opinion

[Daan]

Diesel manual all the way for me. Bear in mind I run the lowest diff ratio available for landy diffs (4.75), with a TDI and 35" tyres, the combination gives so much control and simplicity, its what I prefer. I can see it not working well with 3.5 diffs though, in which case an Auto would be better.

I have seen a lot of Auto boxes fail (probably badly setup and worn out but still) and if your power isnt massive, why throw more away in the cooler?

Daan

[FridgeFreezer]

As for v8's why??? there ****e in water, are getting rarer and harder to replace with a good one, they expensive to run, they all boil at some stage!!!

Mine runs underwater it's not hard, they're also more flexible with power, you don't have to spin the turbo up, they're cheaper to buy & fix, don't do timing belts, heads, turbos etc. like TDi's do and were still built until not so long ago, unlike the 200 & 300TDi which died before the V8 did... I can't understand why anyone would run a TDi

[zardos]

Mine runs underwater it's not hard, they're also more flexible with power, you don't have to spin the turbo up, they're cheaper to buy & fix, don't do timing belts, heads, turbos etc. like TDi's do and were still built until not so long ago, unlike the 200 & 300TDi which died before the V8 did... I can't understand why anyone would run a TDi

Mine sort of runs under water with only a 9 finger rubber glove and good ht leads, the deepest water I've been in was up to the wing tops.

It ran for 5 minutes sat in the water before dying (cause of death was probably a combination of no battery power / water in the fuel due to the fuel filler and vent in the fuel cap being under water, so as it ran under water the vent pulled in water not air).

Both of these problem will affect a diesel (no power - the stop solenoid will cut off fuel, and diesels won't run on water just as much as a v8)

Note my 90 was a diesel before the engine died at around 70k, it got replaced with a v8 and the engine now has 220k on the clock (replacement was done by a previous owner).

The only problem I really have when going in water is seeing where I'm going due to the big steam cloud :-)

[CosZuki]

I just snorted coke in the middle of a library

never thought i would see that in here

[will_warne]

From the results so far I can conclusively show the results are inconclusive

[FridgeFreezer]

never thought i would see that in here

As long as you do it quietly you won't get kicked out

I also note there's no option for a 2WD LT230, which is what some of us are running.

[LittleBlue88]

Gonna be running 3.9 on either 3speed Torqueflite or 4speed ZF in the 109..........eventually!