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.The Merlin are expensive but i do not want to swap from Stage 2 to Stage Merlin's later. That would be even more expensive.kiwicar wrote:If you have the budget to change to Merlins then yes they are a very good base for further modifications and will give you more power straight off, I would also renew the cam at the same time, however this is a little tricky to advise on wether you want an upgrade of cam or stick with the standard one as you haven't as yet said what sort of use you put it to.
One issue here is the LPG, this requires more CR than petrol, and merlins will let you run more CR with petrol without detonation, they are also a high swirl head wich will also help the LPG burn quickly, however you can't increase this much without a change of piston.
I am not the best person to advise on LPG as I hate the stuff
Best regards
Mike
Kevin,CastleMGBV8 wrote:Florent.
The Merlin heads are made by Real Steel in London and they are around £1200.00 direct from them and not the silly price RPI are quoting in case you have seen them there.
If you get advice from RPI always get a second opinion!!!
One of our guys is using them with a semi race cam which I wouldn't recommend for your vehicle and off road use, but the engine is producing a peak of aroung 325BHP with a good wide and fairly flat torque curve.
The 4.6 engine is very head restricted which was not important in a heavy vehicle which requires good low down torque but it does respond well to being modified with free flowing heads and a fast road cam.
One point, does your engine have the Gems EFI with the large square plenum or the later Thor system with the throttle body on the front right hand side?
The later system is torque optimised and will restrict breathing at high RPM even with the above mods.
Second point is that the Merlin heads have I think, 37cc chambers and the late Rover heads are 28cc which means that you will REDUCE the compression ratio unless you use the earlier tin head gaskets or have the Merlin heads skimmed to regain the compression ratio.
For a further increase in compression ratio the rover V8 4.0 pistons can be used.
Kevin.
.Mike,kiwicar wrote:Hi Florent
Kevin is spot on here as usual, and especially with the warning about RPI. Your general aproach of spending money once buying the best components for the job you should keep in the front of your mind at all times.
As a piece of general advice you are better spending time designing your modifications as a packace and not changing bits one at a time it is much cheeper in the long run and you get where you want quicker.
With these principles in mind consider where you want to end up.
Do you want a range rover with a Chevy LS in it? if this is the case then forget modifying the rover engine and save for the LS, your choices are the 4.8/5.3, the 5.7 ally block and the 6 litre engine. The 4.8/5.3 engine comes as an ally block or as a lightweight iron block all versions are cheeper than the 5.7, can easily exceed the output of the 5.7 with a cam change (over 320 bhp for the 5.3 on a well manered road engine) .
The 5.7 is a very good base engine for 420+ bhp and once you get over the extra £500 for purchasing the capacity pays off if you want over 420bhp.
Finally the 6 litre it is the strongest engine by far, lightweight iron block (about 60 lb heavier than the ally block) has about the best heads for porting and the bottom end is good for over 1000bhp as is and braced it can handle over 1600 but they are more difficult to get and over in europe they are more expensive.
If you are going to go rover then for a car like the Range rover the merlins will give you a better engine than stage 4 heads, they breath better at low lift which suites a torque orientated cam better, if it were me I would probably base the engine around the 4 litre pistons with the tops skimmed, using the blower cam from real steel or their stump puller cam, a set of long 4 into1 tubular manifolds of modest bore and a mapable ECU with hotwire manifold set up all ballanced with a standard flywheel should give 250 to 280 real bhp and good torque.
Best regards
Mike
Eliot,Eliot wrote:As noted, the biggest challenge to swapping the engine in the P38 is the BECM connectivity.
The earlier non-thor one would probably be easier due to the fact that the signals from the engine to the BECM are on discrete lines, wheras the later thor(bosch) system used CAN.
My understanding of the overfinch conversion is that they remapped or bodged the gems ecu.
I thought of putting a 36-1 trigger wheel on the front to run both my aftermarket ECU (megasquirt) and also to provide a signal back to the GEMS ecu to think something is still "there"
Kevin,CastleMGBV8 wrote:Florent,
It would help to know where you are based.
You have Gems which is helpful, you could dump the standard ECU and airflowmeter and fit a Megaqsuirt ECU mapped for dual fuel, which would recover a lot of lost power when using LPG.
Compression ratio is stamped on the block next to dip stick just before engine number.
ie. CR 9.34.1 or possibly 8.313.1 for low comp engine.
If low comp then a change to 4.0 pistons would be a big help especially on LPG.
Any idea of how much you are prepared to spend?
Is vehicle used for towing?
Or another alternative similar to the current Range Rover Sport engine, all parts should be available for the swap.
http://cgi.ebay.co.uk/JAGUAR-S-TYPE-S-T ... 20b4f19171
Regards
Kevin.
Looks like Overfinch may have used something like the CANEMS :Eliot wrote:As noted, the biggest challenge to swapping the engine in the P38 is the BECM connectivity.
The earlier non-thor one would probably be easier due to the fact that the signals from the engine to the BECM are on discrete lines, wheras the later thor(bosch) system used CAN.
My understanding of the overfinch conversion is that they remapped or bodged the gems ecu.
I thought of putting a 36-1 trigger wheel on the front to run both my aftermarket ECU (megasquirt) and also to provide a signal back to the GEMS ecu to think something is still "there"
