3.5lt or 3.9lt injected v8??? Which is the better engine?

[skyhighcj7]

Hi Guys,
I am after as much info as a man can take! (but no opinions about the Jeep part)

I am looking to buy a Rangie or Disco to salvage the motor, gearbox, transfer and anything else useful to put into a CJ7 JEEP, yes you heard right, a JEEP, I have owned a couple of early mod Rangies and think the motors are great, light and plenty of go for the CJ7.

I have looked at the info posted and it is great, I really thank the guys who listed all the models, engine, g-box and t-fer info.

The real question is 3.5 or 3.9, pros and cons, and if anybody knows if there is realy much HP and Torque differance..
I have very limited knowledge of the 3.9

Thanks in Advance..

Mark

[nottie]

3.9 all the way.
I am pretty shore they are a 4 bolt main instead of the 2 bolt in the 3.5s.
We run a 3.9 in a rockcrawler. We had to run a final stage at cruiser park last weekend with no oil at all in the motor. Took about 5 minutes of abuse before we finished the stage. Motor is a bit noisey now but typical rover it still runs. This is a motor that has spent alot of time upside down aswell.
Either 1 of them is a peice of piss to wire aswell.

[skyhighcj7]

Thanks champ, glad to here they can take a little abuse, I just needed a little reassurancee the 3.9 was good to go, now the fun begins, track down a donour vehicle.. I think it will be a good engine for the jeep, plenty of power to weight and not to heavy being an alloy block..

[armbrup]

3.5s and 3.9s a basically identical except for the bore size of the 3.9.
same heads, same bearings, only 2 bolt mains. As long as you buy one after say 1980 or so.

3.5s are more tolerant of being overheated as there is more meat around the sleeves.
Depends if you want 11% more torque.

I think Jeeps are a lot lighter than a Rangie so it would go OK with a 3.5. If you got a 3.5 from a Disco the injection is the same as a 3.9 Range Rover motor.

Regard sPhilip A

[Hobie18]

Hey Mark

Phone Murray at Jag & Rover Spares at Kelvin Grove, he imports and wrecks both rangies and discos, should be able to help.

[Troll00]

Try Tony at AJG Spares has a few on the shelf and at a good price.

[RRV839]

i dont know if its just me, but i have a serpentine 3.9 (late) and i havnt driven another, but it seems mine has a bit more poke than otheres ive driven with the v belt's (the earlier engine) i dont know if some of the electrical might be different or what. but yeah thats my opinion.

[lokka]

Sounds like a good mod what sorta gearbox and raito's ya lookin for what raito diffs are you runing and what size tyres ???

If ya keen to run bigger tyres id be lookin for a good 4.6 or even a layland 4.4 as both make heaps more tourqe than the smaller rover 8's and if ya turning bigger rubber the tourqe helps tho with the right raito's the smaller donks will do the job with bigger rubber ...

[skyhighcj7]

Sounds like a good mod what sorta gearbox and raito's ya lookin for what raito diffs are you runing and what size tyres ???

If ya keen to run bigger tyres id be lookin for a good 4.6 or even a layland 4.4 as both make heaps more tourqe than the smaller rover 8's and if ya turning bigger rubber the tourqe helps tho with the right raito's the smaller donks will do the job with bigger rubber ...

Will prob stick with 33's until I destroy axles and do an upgrade, they are a pretty good all round fit for a cj7, in saying that we all know what will really happen, b y the time i get to buying tyres it will be 35, 36, 38+ tyres & dana 44's
I agree with more torque the better but my main concern is weight, I have had a couple of Rangie's; 1 with the 3.5 which went ok and the other with a holden 253, it had more grunt but the weight made it really crap to drive, loaded up front suspension and it handled like a whale, bit reluctant to go to heavy, I would like it to drive reasonalbe on/off the road and around corners not just in a straight line. The cj7 is fairly light & not a real big truck, except when you fit the 10''lift and 44''tyres as the do in the US.

Does anyone know the weight of a 4.4 or if its much heavier than a 3.5/3.9?

Thanks Mark

[GRIMACE]

from memory (not a very good one) about 20lbs heavier.

memory is very bad more like 60lbs

[lokka]

If the 4.4 is any heavyer it aint much there near identical the casting is verry similar and so are the internals tho it would be handy to know the difference tho as for drivability the 4.4 in my rangie dont make it any worse tho id say a holden V8 would ...

If ya want lightweight grunt go the LS6

[nottie]

i dont know if its just me, but i have a serpentine 3.9 (late) and i havnt driven another, but it seems mine has a bit more poke than otheres ive driven with the v belt's (the earlier engine) i dont know if some of the electrical might be different or what. but yeah thats my opinion.

We have come to that conclution aswell

[known 2]

isnt the 4.4 becoming rarer and rarer? ....
i've allso ben looking at puting a rover v8 in my lada. and have learned that the series 2 discovery 4.0l v8 used boche electrics wich were far more reliable then the old lucas style in the 3.9.

[armbrup]

I disagree that the 14CUX is unreliable. My 92 has never had a problem, and problems are restricted to sensors in most cases.
Now Lucas alternators are another thing entirely.

Good luck with the Bosch. Remember that the body and transmission functions are included in the ECU, and each ECU is coded to the VIN of the car it is in.
I am not sure ,( as I have never heard of anyone retro fitting a Bosch),but I think that it is not possible to use a coded ECU in another car. I read in a Pom magazine that you have to buy a new ECU with the body functions etc disabled.
This is because the theft problem is so bad in UK.
I would really be interested if anyone has ever retro fitted one.
Regard sPhilip A