The V8 Owners Forum -

Hi, new to the V8 sciene, please bare all the dum questions....

I have a 3.9 Discovery Auto, which I use for Off roading/green laning and during the week it pulls my 3.5Ton trailer.
Im looking to improve the Torque band, from idle to 3000rpm.
Im goin to change the cam to achieve the above...
I will be running LPG soon, and was told that force induction works great with LPG.
Now, Im not sure what size blower to look for, I had a quick look on ebay and saw the following: Eaton M45, M90, M112, Merc SLK200 blower.

Is any of then any good to use on the 3.9V8. Im not looking to run hi boost, some thing around 6-9psi, Im just after torque


I will appreciate any info/guidance

Regards
Tiaan

The M90 may work, but the M112 is better and fitted to the 4l V8 Jags & Range Rovers so more suited to your engine. Not sure about the lpg with boost bit as never seen it before!

Will work fine with LPG but Id should go for a M112 as a M90 is to small for your engine needs.

Bosvark wrote: Im not looking to run hi boost, some thing around 6-9psi, Im just after torque

Torque will come from the boost you run, more boost = more torque.8-9 psi will give you approximately 50% more torque. But definitely use a roots or screw type blower. The boost curve on a centrifugal blower will deliver all of your torque and hp right at the top end of the rpm scale, and that is not really where you want it! It makes for impressive dyno numbers, and they are generally easier to fit, but don't go there.

Conrad

Thanks for all the info.

I will start looking for an Eaton M112.
Is it the pulley size that determine the boost pressure? Is there a table that give relation between x Boost @ Y speed with Z pully size???


TopCat.
what cam did you use in the end. According to some of your other posts, you are also aftr low down torque.

Hi, I used the proper blower cam, available from real steel or V8 tuner. Not that I have had a lot of driving experience with the car or other blown cars yet but I'm happy with how it runs at the mo!

And yes- boost is determined by pulley sizes, I take it your 3.9 is on efi? If so I cant advise you any further with fuelling as I'm on a carb!