Hi,

Can anyone think of a problem in putting the 4.0ltr EFI onto a 3.9ltr

Ta

Darren

Nope... not at all, since they're both exactly the same engine.. both have a displacement of 3950 CC. The only real difference is in the compression ratio, 8.1:1 for the 3.9 versus 9.34:1 for the 4.0 engine. There really should be no problems whatsoever...

darrens, if you havent got the efi already have a look for the weber 500 conversion as its spot on for the 3.9 and much easier to cope with any performance mods in the future as all the pre gems systems are 10 years old now and the bits aint cheap

Not an easy conversion sorry....

The gems or later thor systems require the following:

Later timing cover, sump, cam shaft cam sensor, oil pickup etc.

You will also need the flywheel with timing ring and sensor. the hardest part will be fitting the sensor as it pokes back to the flywheel under the exhaust manifold so will need some tricky cutting and drilling.

Coil pack.

Afte that you will then need to replace the V fanbelt with a flat ribbed belt and ponce around with tensioners etc.

Not worth the effort unless its a complete engine and EFI swap out, Its much easier to go backwards !

I ran a 4.6 rover with 3.9 front cover and cam using megasquirt, thats the way to go... Its under my bench now as I,m building a blade engined BEC, tempting to V8 it but I think it will end up being slower to 100.

Regards Mark

I'm in a bit of a diallema at the moment as to whether to go for Injection or Carb, I don't mind the additional work involved in injection, but getting doubts as to whether the benefits are worth it (if there are benefits)

Anyone got anyother views on injection vs carb, btw I curently have a holly with 3.9 RV8

Regards
Darren

I like injection, its clean an reliable these days. If you run a holley then you want to look at modified floats as your cornering ability may cause surge issues.

Horses for courses...

You can pick up the RV8 3.9 complete inlet manifold with pleneum, injectors etc on Ebay for £25, build up a basic megasquirt for £115 and away you go.

You can also lower the top or turn the inlet ala westfields so make the lump a better fit under the bonnet.

There is nothing special about later gems or thor RV8 injection, just get a standard 3.9 for the same power results.

Regards Mark

Hi All,

New to the Locost forum, just spotted this thread.

I am currently in the process of converting my 3.5 RV8 from Carbs to EFi using the V3 Megasquirt and a throttle body unit which replaces the carb - un bolt one and bolt the other in - it uses the same air intake as on the carbs.

This seamed to me the easiest first step, having looked at all the other options. It also allows for the conversion to be done in easy steps.

Interested in others conversions and is any one here running Megasquirt on RV8


Melf

Melf

I managed to get ahold of a 3.9 injection, but am thinking of using the V3 Megasquirt system and retaining the 3.9 plenum chamber, airflow meter etc. Would be interested to here how you get on. I think I'm probably gonna go the megasquirt route, one thing I noticed about the Megasquirt is that it only allows one Lambda sensor or two but switching between either or.

Which supplier did you get your Megasquirt from btw

Cheers
Darren

Hi Darren

I used Bill Shurvinton for all the MS stuff - he has most of the stuff of the shelf, loads of help. If you need his contact details let me know and I will mail them to you.

As for the lambda sensor - to start with I will be running with out this, as I understand it you only need it to fine tune the settings. I am trying to keep things very simple to start. In fact I will only be using temp sensors and Throttle Position sensor to start. Taking the timing from the existing coil etc. Once I have all that running, then I will look at the coil pacts and electronic timing from the MS unit and develop on from there once I understand how it all works.

I will keep you posted of progress - if you want any other information, let me know


Melf