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RV8 3.5 > 4.6 + stroker advice
Posted: Thu Dec 07, 2017 11:00 am
by Kit
Hi all,
I'm after some advice, I want to build a 4.6 to go into a Defender but ideally I want to avoid all the 4.6 electrics sensors...etc as it's going onto a comp safari racer which will have some rough and tumble.
I have a 4.0 P38 and 3.5 EFi RRC which are laid up, so I can take parts off them?
What would you recommend?
Posted: Thu Dec 07, 2017 12:59 pm
by garrycol
Start with the 4.0 as it is the same block as the 4.6. Just put the 4.6 crank in, use the 4.6 conrods and for a higher compression ratio us the 4.0 pistons and go from there.
Garry
Posted: Thu Dec 07, 2017 5:15 pm
by Kit
Thanks for confirming Garry, where can get a 4.6 crank/conrods for a good price new/used?
What parts would you recommend to manage the ignition?
Ideally I would like to run it on EFi:
Would it be a massive pain to keep the 4.0 EFi?
Would I be better using the EFi off the 3.5?
Webber 500?
Posted: Thu Dec 07, 2017 7:14 pm
by DaveEFI
If you intend going EFI, what sensors are there you wish to avoid?
Posted: Thu Dec 07, 2017 7:23 pm
by Kit
Mainly the MAF, I'd probably replace it with a air temperature sensor if I ran a MS2
Posted: Thu Dec 07, 2017 9:26 pm
by ChrisJC
The 4.6 sensors will be much newer than the 3.5 sensors.
I would do as suggested above to get a 4.6 engine. I would probably ignore the 3.5, but I would research what sensors are needed for your preferred fuel injection system, and choose the inlet / ignition system that suits you best.
Chris.
Posted: Fri Dec 08, 2017 2:26 am
by garrycol
Kit wrote:Thanks for confirming Garry, where can get a 4.6 crank/conrods for a good price new/used?
What parts would you recommend to manage the ignition?
Ideally I would like to run it on EFi:
Would it be a massive pain to keep the 4.0 EFi?
Would I be better using the EFi off the 3.5?
Webber 500?
Note that I am in Australia so I cannot help where you would get a crank etc - noting how are you going to get a 4.6 engine without a 4.6 crank.
If you are confident with Mega Squirt then go with that for ignition and injection but if you are new to it, it is not as simple and people make out
You can run the 4.0 EFi system but work will be required on the ECU to make it run stand alone (I have assumed it it a Thor system - not sure about a GEMs system. It will run the ignition as well.
I would forget anything off the 3.5. I have heard the Webber works OK but you will still need something to run the ignition.
Garry
Posted: Fri Dec 08, 2017 9:40 am
by DaveEFI
Kit wrote:Mainly the MAF, I'd probably replace it with a air temperature sensor if I ran a MS2
Ah - right. But a MAF is common to most factory injection systems including most RV8s. The first RV8 EFI used a flapped AFM, which is definitely to be avoided.
As you say, MS doesn't generally use a MAF, but uses a combination of engine vacuum and throttle position for much the same thing.