Thor Engine - Pros and Cons

adarmo · Post by **adarmo** » Sun Jun 21, 2009 8:16 pm

I have been offered a rebuilt and balanced 4.0 Thor engine - the owner had it all done and then crashed the car (I know the engine builder).

I'm looking to install it in a sportscar.

I believe this engine gives excellent torque but is it at the expense of bhp (although I'm only looking for 240ish) I presume the Motronic (?) is a bugger to transplant so I'd stick a Megasquirt on which I presume would work better as I'd want a high lift cam fitted.

Is there any pros / cons with this engine as opposed to any other ?

Thanks

topcatcustom · Post by **topcatcustom** » Sun Jun 21, 2009 8:32 pm

I'm sure you could just swap the inlet manifold for something with shorter runners to get some more top end bhp easily enough....

mgbv8 · Post by **mgbv8** » Sun Jun 21, 2009 9:06 pm

Why are you worried about bhp when torque is the fun part??

RoverP6B · Post by **RoverP6B** » Sun Jun 21, 2009 10:07 pm

The Bosch Motronic engine management system as I understand it is designed to maximise torque and fuel economy at the expense of horsepower. The inlet manifold was designed to accompany the system.

As such the system runs with a continual ar/fuel ratio of 14.7 : 1 under all conditions and in all situations, and is designed not to allow changes to be easily made.

Ron.

adarmo · Post by **adarmo** » Mon Jun 22, 2009 8:22 am

Is it easy to swap to a Hotwire type intake though, I was told it wasn't.

Torque is for tractors, bhp for sportsbikes, I'm building a Sportscar so I want enough of both.

From what I've seen of Adams's prices I wouldn't be willing to pay to keep the std inj. so has anyone played with aftermarket on the Thor to see what results ?

Thanks

paul c · Post by **paul c** » Sun Jun 28, 2009 9:39 am

my plan is to modify the thor manifold for running a hotwire system, several guys in Australia have done it to use the thor manifold on 3.9s in Rangerovers.

topcatcustom · Post by **topcatcustom** » Sun Jun 28, 2009 7:48 pm

Sure it would be do-able, but there's no escaping the fact that the thor manifold is far more suited to torque and will leave it a bit breathless at the top end! But if you're not too interested in revs it should be no problem

adarmo · Post by **adarmo** » Mon Jun 29, 2009 9:31 am

Has anyone done the swap (either way around) or got a link to see whats involved ?

badger · Post by **badger** » Tue Jun 30, 2009 12:11 pm

I run a thor manifold modified to use a hotwire injector, afm and ecu (with a Mark Adams "Tornado" chip) setup on my 4.6 landrover 110. I used a Lund LE1 cam, but to be honest I've never been all that impressed with the power delivery. Stonking torque at 3000rpm however. The engine should, on paper at least, be making 250bhp and 290lbft (with it's modified heads etc), but it doesn't feel like it's even coming close. One of my thoughts was to change to a Viper Hurricane or Cyclone cam and a 3.9 plenum and see what that gives me, when I find the time!

Be warned, there's a lot of work required to fit a hotwire efi to a thor manifold, here's some of what I can remember off the top of my head...
1. Front face needs machined to allow fitment of a thermostat housing.
2. Rear needs a coil pack mounting lug removing to allow clearance for hotwire fuel rail and pressure regulating valve.
3. No facility for temp gauge sender (hotwire one for ecu fits ok though), I modified the heater outlet pipe to take a sender, gives a slight delay in readings but works fine.
It clears the efi dizzy ok (I was told it wouldn't by a so-called specialist near Norwich!), and you have to use the 3.9 injectors as the 4.0/4.6 "green" ones are different flow rates and not even Mr Adams does a chip for the 3.9 ecu to use them, or at least he didn't at the time.

Eliot · Post by **Eliot** » Thu Jul 02, 2009 2:56 pm

How about Fitting a hotwire manifold and plenum and then use megasquirt. The engine should have a 36-1 wheel on the flywheel already.
Get it running and tuned on that, then look at shorter / bigger trumpets and throttle body etc.

I looked at a thor manifold once with a view to twin throttle bodies on a TVR 500, but it was pretty clear that it wasn't suitable for high power. The long thin runners are best for torque and the purpose intended (a 4x4):
Here's a cutaway:
http://www.mez.co.uk/rovermanifolds/thorcutaway.jpg

desertrover · Post by **desertrover** » Tue Jul 14, 2009 5:41 pm

I´ve changed my 3.9 cam in my 4.6 to a PIPER 270/110 and this was the worst I did to the engine.
Power comes much higher in revs.
Before I just had to floor the throttle in the dunes of Tunisia and beated everything that was in the group with me, and now with the Piper on tarmac a LR 110 Td5 ( standard, no chip tuning, showed me his pipe on a road in Ethiopia ). I change back to the 3.9 cam, that I was satisfied with, I just changed in the stupid look for more power even the engine ran great.