RV8 4.6 Induction - Ideas

garrycol · Post by **garrycol** » Sun Jul 19, 2015 2:25 am

I have put similar threads on other forums but am looking for different ideas from different groups with relevant information. I am in Canberra Australia.

I have a Landrover FC 101 with the mid 70s version of the 3.5 V8 with twin strombergs CD 175s and has the oil pump driven from the cam shaft. It is dual fuel with an old LPG system that works well.

I want to replace the 3.5 with a 4.6 – the 3.5 has enough torque at slow
speeds but runs out of puff at highway speeds and uphill – 2500rpm and up. The change will initially be just on petrol but later I will add LPG but
as a separate project.

I obtained a top hatted low km 4.0 Thor engine with no ancillaries (I do
have thor inlet, fuel rail and injectors) and put in a 4.6 crank and rods but left the 4.0 low comp pistons so compression in the 4.6 works out about 9.2:1. The heads have been deburred and port matched but not polished. It has a new hi-torque cam.

My initial intention was to go MS using the Thor manifold but I am bit daunted by the installation process and setup and its cost when everything is taken into account. I would really prefer an off the self product that can be put on and work with minimum mucking around. Forum discussion on MS is very confusing with a lot of vested interested at play.

So I am looking at options.

In addition to the old 3.5 and all its ancillaries and the fully rebuilt 4.6, I also I also have a dead 3.9v8 with its timing cover and 4CUX manifold and injectors in place.

So options considered.

- Thor Manifold and MS - a bit complex for me and expensive.

- RPI suggested the 3.9 hotwire induction system with their ECU mod - is very very expensive and I will either need megajolt to work ignition or change to a dissy (I have the timimg covers - just need the cam)

- Some Americans have suggested the Holly injection system that replaces a holly carb but is very very expensive - but is install and forget as it learns - ignition issue as well

- RPI also suggested as an alternative to the hotwire system their Edelbrock Weber 500 CFM conversion - expensive if I buy from the UK but cheaper locally - not sure about offroad use - ignition issue as well.

- Americans also suggested the Holly Truck Avenger 670cfm carb but it is too big for a 4.6 but their 470CFM would suit better - locally sellers advise that it is an offroad carb and not suitable for onroad use or towing due to high fuel use - ignition issue as well.

- Rejet the CD175 Carbs - will work but power will be down and fuel consumption will still be high. ignition as well.

My preference is still to go injection - either Thor or Hotwire and if there was a local expert on MS I would go that route but there are none.

So the Edelbrock Weber 500 would seem to be the most cost effective and easiest with a dissy providing ignition. Not sure how much worst fuel consumption and torque will be with a carby setup vs an injection setup.

So given the above, I am open to suggestions or comments. Costs are a consideration as some of the options cost more than the rebuilt 4.6 itself and afterall the 101 is not a sports car.

Thanks

Garry

Canberra
Australia

ChrisJC · Post by **ChrisJC** » Sun Jul 19, 2015 7:39 am

Millions of options - everybody will have a different opinion.

You could stick with a 100% factory Thor setup, and run it from a Discovery II ECU + extra dongle to defeat the immobiliser. The ECU will cost you about £50 from eBay, Having it remapped and getting the dongle is about £500 from Mark Adams.

Chris.

Robrover · Post by **Robrover** » Sun Jul 19, 2015 9:04 am

How about twin SUs and inlet manifold off an SD1? They can work well on a 4.6.

You still need to sort the ignition. As you're in Oz, I highly recommend Performance Ignition Systems in Melbourne who make the Scorcher dissy with machined Ford Falcon body and all Bosch Holden/Ford internals and cap. You just need to provide the Rover drive gear.

DaveEFI · Post by **DaveEFI** » Sun Jul 19, 2015 10:22 am

Pretty well all those options are going to increase the peak torque considerably. Is the transmission going to be up to it?

If the standard engine was fine at lowish revs but fell of as they rose, easy enough to bring it up to car spec which didn't.

garrycol · Post by **garrycol** » Mon Jul 20, 2015 12:59 am

Thanks for those comments.

Chris - I was not aware that the Bosch Motronic ECU could be made to run in isolation. While the cost is high ultimately given the stuff I have is certainly an option - I will contact Mark Adams to see what the options are. I knew that he chipped/remapped ECUs but where they were being used in their original vehicle - not as a stand alone ECU - thanks

Rob - thanks for your suggestion on the SUs - I hadn't seriously considered that option - looking at it more closely it would seem 2" rather 1 3/4" would be needed to provide appropriate CFM at higher revs. Would the SD1 manifold be able to flow enough air for the 4.6"??

As far as the Dizzy goes I currently have a Holden Bosch V8 dizzy and Bosch electronic ignition system on the 3.5 so it will be up to a 4.6.

Dave - the gearbox is the Rover LT95 so more than a match for the 4.6. The current engine is judt too small to lug a 101 around at highway speed. It was never designed for it, particularly when the brick aerodynamics kick in. Torque low down is masked by the gearing but in top gear on the highway it starts to run out of steam as speed increases and when hills come up - the engine needs more torque up around 3000rpm where it lives most of the time on the highway and a 4.6 should deliver this.

Thanks to everyone for your thoughts and if you think of anything else I would be like to hear them.

Garry

unstable load · Post by **unstable load** » Mon Jul 20, 2015 6:41 am

garrycol wrote:Rob - thanks for your suggestion on the SUs - I hadn't seriously considered that option - looking at it more closely it would seem 2" rather 1 3/4" would be needed to provide appropriate CFM at higher revs. Would the SD1 manifold be able to flow enough air for the 4.6"??

Garry, I certainly wouldn't go bigger than 2" carbs. There's a bloke on The Classic Rover Forum that has a 4.6 running SU's, go and have a rummage on there with the search engine, or join up and ask about it. I tried to find him, but my search skills are rubbish.

The manifold will be fine, as far as I understand.

kiwicar · Post by **kiwicar** » Mon Jul 20, 2015 9:29 am

2" sus and a tidied up and port matched (not gasket matched) SD1 manifold would be a very good match for a the 4.6 in a vehicle like the 101.
do you have the auxilery drive winch fitted to the 101? If you don't have one you might consider finding one of the GKN/Fairy overdrive units for the LT95 box and transfer case like this http://www.ebay.co.uk/itm/Landrover-Fai ... 3cfe5fb895 they act as a 3/4 gear splitter which can make highway driving a lot more pleasant. I would also consider going over to a crank triggered ignition system like the MSD 6 digital series or megajolt.
Best regards
Mike

garrycol · Post by **garrycol** » Mon Jul 20, 2015 9:49 am

Thanks for those comments - actually I had a look on ebay Aust tonight and there are two Jag 4.2 2" SUs on there.

Mike - yes I have the Noken winch fitted but I also have a Fairy/Superwinch Overdrive fitted as well. The overdrive works well in the flat outback but is no use in anything but flat country as you are constantly changing in and out with the terrain. The 3.5 really doesn't have the torque to pull an overdrive.

I googled MSD 6 digital series but it seems it still needs a dizzy to fire it with adjustments in the unit. Familiar with Megajolt.

Cheers

Garry

kiwicar · Post by **kiwicar** » Mon Jul 20, 2015 10:46 am

Hi
you may well find with the 4.6 the extra torque lets you make more use of the overdrive you probably will not be free of changing gears because of the narrower power band of the larger engine but it should be better. I didn't realise you could have a winch and an overdrive!
The MSD units are just a control box, but a very good one, you need a locked dizzy with one, and crank trigger kit like this http://www.ebay.co.uk/itm/MSD-Ignition- ... 5d4c3adbc1
this set up has a big advantage over the megajolt in that the wheel has high power magnets in it that give a big fat signal to the sensor, the magajolt uses a toothed steel disc and a phase locked loop circuit to synthesise a trigger once per rev.
best regards
Mike

DaveEFI · Post by **DaveEFI** » Mon Jul 20, 2015 12:58 pm

Though MegaJolt basically used EDIS? The toothed wheel and VR sensor on EDIS has been fitted to many millions of vehicles or all sorts. And is extremely reliable.

How many magnets does that wheel have?

EDIS uses a 36-1 toothed wheel. Fewer pulses gives poorer resolution.

ChrisJC · Post by **ChrisJC** » Mon Jul 20, 2015 5:14 pm

For reference, I have a 4.6 in my Landie. It runs on 2x 2" SU's, suitably modified to be handed. The manifold is ported out at the carb end.

I run Megajolt Lite (+EDIS8) for my ignition system.

I had the carbs rolling roaded to ensure they were set up properly.

It runs very well.

It is also coming off in the not too distant future as I am going to switch to Thor + standalone ECU from Mark Adams.

Chris.

DaveEFI · Post by **DaveEFI** » Mon Jul 20, 2015 5:22 pm

Have you already got all the Thor bits, Chris? Have a pretty well complete top end which I'll never use. Everything except the ECU.

ChrisJC · Post by **ChrisJC** » Mon Jul 20, 2015 8:23 pm

DaveEFI wrote:Have you already got all the Thor bits, Chris? Have a pretty well complete top end which I'll never use. Everything except the ECU.

I purchased a complete Range Rover P38

Thanks for the offer though.

Chris.

garrycol · Post by **garrycol** » Tue Jul 21, 2015 12:25 am

kiwicar wrote:I didn't realise you could have a winch and an overdrive!

Mike

The 101 LT95 has a power take off (PTO) at the bottom of the transfer case that goes out sideways to drive the winch. This leaves the rear standard PTO to have the overdrive fitted.

Garry

garrycol · Post by **garrycol** » Tue Jul 21, 2015 12:29 am

ChrisJC wrote:For reference, I have a 4.6 in my Landie. It runs on 2x 2" SU's, suitably modified to be handed. The manifold is ported out at the carb end.

It is also coming off in the not too distant future as I am going to switch to Thor + standalone ECU from Mark Adams.

Chris.

To help me understand what to fit as I do have options - if you are happy with the SUs and megajolt what advantages to you expect to achieve with the Thor system given the costs involved over what you currently have.

I can go SUs but I also can go straight to do what you intend for about the same cost.

Cheers

Garry