RV8 4.6 Induction - Ideas

kiwicar · Post by **kiwicar** » Tue Jul 21, 2015 6:56 am

Hi
I think your choices here are not ones of cost or reliability, you have said the cost is the same and both are reliable. Also well tuned and maintained SUs can be (nearly) as economical as injection, I think your choices are of simplicity of fixing it if something does go wrong and how you want the final set up to look, twin 2" SUs on a 4.6 will look pretty much stock, it is also only really those in the know who will realise the 101 should be on Strombergs. Putting it on injection it will mean if anything does go wrong then you are in for a more complicated time trying to sort it out. It will also look quite different to stock.
best regards
Mike

DaveEFI · Post by **DaveEFI** » Tue Jul 21, 2015 8:11 am

If you use MegaJolt and SUs. you are getting very close to the amount of electronics needed for full injection. Which is why If I were considering this, I'd also look into using a MegaSquirt ignition only, as it gives the choice of going to injection at a later point if needed.

ChrisJC · Post by **ChrisJC** » Tue Jul 21, 2015 6:11 pm

garrycol wrote: 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.

From a functional point of view, there isn't really any advantage. My reasons are:
1 - It will be the only Series IIA Landie with a Thor engine in it. Most people avoid the later fuel injected engines because of their complexity
2 - I've got one in my Range Rover and I quite like how it starts and runs.
3 - I think it has the most interesting under-bonnet look.
4 - It will be a challenge.

So not really very helpful!

Chris.

garrycol · Post by **garrycol** » Wed Jul 22, 2015 4:15 am

ChrisJC wrote:From a functional point of view, there isn't really any advantage. My reasons are:
1 - It will be the only Series IIA Landie with a Thor engine in it. Most people avoid the later fuel injected engines because of their complexity
2 - I've got one in my Range Rover and I quite like how it starts and runs.
3 - I think it has the most interesting under-bonnet look.
4 - It will be a challenge.

So not really very helpful!

Chris.

Very helpful and honest.

Ok - thanks to everyone who posted - for me a very worthwhile exercise as I learned a few things I did not know before

So on the basis of all the information I have gleaned from here and elsewhere I am leaning towards using the Thor injection system with the Mark Adams standalone ECU. Failing that the 2" SU carb option with either Megasquirt or a dizzy (different timing cover) for ignition.

My reasons:
Thor
The Thor does go on the engine I have and I have two full sets of manifolds, fuel rails, injectors and injection harnesses. It does control ignition and I know as a later project injected LPG does go on it.

Some caveats are that the ECU must be completely stand alone and accept throttle cable input via ???? as the 101 definitely does not have TPS. Also it will need to take crank position from something like a MS Trigger wheel as I need to use the 101 flywheel and it does not have the "magnets" in it to fire the crank sensor which I do not have at the moment. There are no speed inputs but I assume the remapped ecu takes that into account.

The Thor manifold provides increased torque below 3500rpm that I want.

SUs
These are available and for a reasonable price. Not sure what the difference is between a 3.5 Landrover manifold and an SD1 manifold is but as people have mentioned specifically the SD1, there is obviously a reason. It will be hard to get one locally but I guess they are reasonably plentiful in the UK so I could get one there.

I can stay with the 4.6 cam and timing cover which definitely means MJ (or ignition on MS) or I can change to the old timing cover meaning I can use my current GM V8 dizzy and electronic ignition - or using MJ.

The cost of getting a new cam to replace the brand new 4.6 cam I have is about the same as building a MJ so is a cost neutral exercise to MJ vs not.

While I am now thinking of these two, the others are still in the back of my mind.

Thor with MS will cost about double the standalone Mark Adams ECU and I have no one local to assist if needed. I could go the Hotwire injection system I have with a Tornado Chip but with MJ starts to become expensive. The Edelbrock Weber 500CFM carb is there but needs a new edelbrock manifold that gets expensive as well as MJ for ignition. Lastly I could just jet the CD 175s and they would work but performance and economy would suffer - as well I need to sort ignition.

So that is where I am at - thanks for the input I appreciate it and if you have more brilliant ideas - lets hear them.

Cheers

Garry

garrycol · Post by **garrycol** » Wed Jul 22, 2015 4:19 am

double post

DaveEFI · Post by **DaveEFI** » Wed Jul 22, 2015 9:04 am

Not quite sure what is more complex about the Thor than the Hotwire to fit to a carb engine. I have both here.
It was my intention to fit the Thor top end to my SD1 3.5,, but was put off the idea by others saying I'd gain at the bottom end, but lose at the top end. Not what I want with a sporty saloon car - but can see the advantage with a 4x4.

But I didn't even consider using it with the Bosch ECU. Might have done if fitting an entire Thor engine. The problem being the cam and crank signals, as well as the immobiliser. And that the Thor is designed for engines with catalytic converters.

I was going to use the existing MegaSquirt 2, and stay with the batch injection I was using with the modified flapper system. But that was several years ago before the MS3 was common, and sequential injection is easy with that.

The snag as I see it with a generic re-mapped Bosch ECU is going to be is it re-mapped for your exact engine specification? A programmable one like MS etc can be for any engine spec, and by yourself.

garrycol · Post by **garrycol** » Wed Jul 22, 2015 10:04 am

Hi Dave - the engine I am building is not a carb engine - it is a Thor engine and I already have most of the gear that is needed to operate it. The issue was always how to induct it given the standard ECU need to talk to its parent vehicle. The Mark Adams stand alone ECU option which I was not aware of make using the Thor gear so much easier.

I will just have to get a suitable fuel pump to charge the fuel rail and sort the crank shaft position sensor - it has the camshaft sensors already in place.

The standard Thor map with its links to the Body Electronic Control Unit removed will work fine.

The carb 3.5 is the engine coming out - it is not being taken up to 4.6 spec. It will not be used and will be surplus to requirements.
The 4.6 is a completely different engine.

Cheers

Garry

DaveEFI · Post by **DaveEFI** » Wed Jul 22, 2015 12:55 pm

Yes - I'm aware of what you want to do.

Just not convinced the route is ideal.

Are you keeping the catalytic converters?

jjsaul · Post by **jjsaul** » Wed Jul 22, 2015 1:44 pm

I've got an RPi 4.6 in a range rover classic - that's running the factory 3.9 efi setup with a tornado chip on the ecu. Everything else induction / ignition etc is factory. Not sure what differences there are on the Thor lump but maybe some options there?

DaveEFI · Post by **DaveEFI** » Wed Jul 22, 2015 2:17 pm

The Thor has mapped ignition. The injection is Bosch Motronic, so pretty well state of the art at the time. The ECU talks to both the air suspension and the gearbox CUs, and has a sophisticated anti-theft system.

I'd guess there would be little advantage in 'chipping' a standard Thor engine. Or going for an aftermarket ECU. The difficulty is getting it to work 'stand alone'.

However, some aftermarket ECU makers do a conversion kit for Thor engines. Not cheap at about £1500.

ChrisJC · Post by **ChrisJC** » Wed Jul 22, 2015 6:07 pm

One issue with making the Thor engine run 'stand alone' is that you need a manual flywheel. There were no UK market vehicles fitted with Thor + manual transmission, so a suitable flywheel is a rare beast (there were export markets with that option).
The trigger pattern is 60-2, so totally different to the 36-1 setup.

I found a flywheel, and I also found two companies who will make you one:
TTV Racing
Rakeway - http://www.rakeway.co.uk/page28.html

The throttle is via a cable, so no issues there.

I plan to keep the cats on my install, so that should be fine.

It is just the emissions control on the fuel tank that I haven't worked out yet.

Chris.

garrycol · Post by **garrycol** » Thu Jul 23, 2015 7:43 am

Thanks for the comments - I am in Australia where manual D2s are relatively common and we do not have cats.

The current rate for a standalone Motec Bosch ECU conversion is about £500. This is about the same cost as getting a 4cux ECU modified to run a 3.9 Hotwire injection system on a 4.6.

Garry

DaveEFI · Post by **DaveEFI** » Thu Jul 23, 2015 8:43 am

Other bit that interested me when I looked at using the Thor top end as a conversion is the fuel rail. It is much smaller than the hotwire one and has no return. So guessed it uses a PWM controlled high pressure pump. The pump on mine is external - the RR internal to the tank. So did wonder if there was a suitable external one? I've read if you control the speed of one designed to run continuously with a return, it may overheat?

SimpleSimon · Post by **SimpleSimon** » Thu Jul 23, 2015 4:19 pm

DaveEFI wrote:Other bit that interested me when I looked at using the Thor top end as a conversion is the fuel rail. It is much smaller than the hotwire one and has no return. So guessed it uses a PWM controlled high pressure pump. The pump on mine is external - the RR internal to the tank. So did wonder if there was a suitable external one? I've read if you control the speed of one designed to run continuously with a return, it may overheat?

Not so much PWM pump more likely FPR at the rear of the vehicle or at the pump end (most are nowadays) this fuel filter may give you another way of doing things these sit in the middle of the car with flow and return and built in FPR 2.5 BAR IIRC

you just need to run a vacuum hose to the reg https://www.google.co.uk/search?q=bmw+e ... BfXdI3M%3A

DaveEFI · Post by **DaveEFI** » Thu Jul 23, 2015 4:38 pm

Interesting, Simon. Was intrigued by the tiny pipe on the Thor, so assumed it ran at much higher pressure.