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1.6 to 1.8 swap


RobT

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I need to change my clutch fairly soon which will mean pulling out the mk2.5 1.6 engine. I've had a cunning thought to drop a mk2.5 1.8 in its place as ill get an extra 35 bhp for a few quid.

Do any of the sdv experts know if the engine is any taller or if the wiring and ecu are the same? 

I don't want to start messing with the loom too much as it's a bit beyond me but would like a bit more oomph.

Maybe best to trade up to one already fitted

Your thoughts will be much appreciated 

 

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Vvt doesn't fit under the bonnet

Think your wiring will need a bit of adapting. What's your plan for ecu?

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Yes the 1.8 is roughly 3/4" longer and a similar amount taller than the 1.6.

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How about a high compression mk1 1.8 - 160bhp. I need to rebuild the bottom end though :blush:

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The 1.6 uses smaller clutch, flywheel so saves weight outside the engine itself. I'd stick with it unless you want many powers.

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23 hours ago, darve said:

Vvt doesn't fit under the bonnet

Think your wiring will need a bit of adapting. What's your plan for ecu?

Wanted to stick with the original. Perhaps that's not possible. 

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The mk2.5 1.8 vvt uses a totally different  Ecu from previous versions 

in that it is “adaptive “ so as to control the vvt aspect and includes extra sensors as well it also has to run through the immobiliser and instrument binnacle circuit boards from the mk2.5

i spent a long long time trying to avoid this to no avail on my s/c conversion in the end I used it as is 

sorry for the bad news and as above the vvt actuated is on top of the engine making it significantly taller

 

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The map would be wrong. Doubt MAF would compensate enough. Ecu connectors probably different so doubt could swap ecu due to wiring differences

You'll be able to see here: http://neomiata.com/garage/index.php?path=Wiring+Diagrams%2FWiring+Diagrams+1997-2000/

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Thanks for all the comments guys. Since going through these I've found that I've made a slight boob in that I reckon my car is mk2 and not mk2.5 as its a T reg which is 1999.

I'm sure it doesn't have an immobiliser but as has already shown in this thread - what do I know??

Does this news mean that a mk2 1.8 is a much better option now? I realise that my exhaust will need modifying but will this run on a 1.6 ecu? I think the throttle body, coils and a couple of sensors need fiddling but could this be back on?

Also has anyone tried to lighten a standard flywheel? I wany to use a standard clutch but am considering adding some holes for extra reviness. I think I can get an aftermarket one for about £300 but may be able to mod one for next to nothing so its an attractive mod.

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your 1.6 ecu won't run a 1.8. the map will be all wrong

please don't drill holes in your flywheel :o these need to be well balanced. I had mine very carefully lightened and balanced by a machine shop @Mark (smokey mow) can you remember what it's called

think I have a stock 1.8 flywheel kicking around (unless I took it to the tip after dropping it on my wheel arch.....) you're welcome to have.

you could use the 1.6 flywheel and clutch with a 1.8 if not running lots of power

you really need to think about going aftermarket ecu if you're going to complete engine upgrades / swap. you could of course install a wiring loom and ECU from a mk2 1.8

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Rob if you get a MK1 1.8 it will fit, you will better fitting a ME221 ECU, I have a manifold and down pipe you can have also a very lightly used clutch and flywheel, I think you will do better dumping the MAF and using inlet air temp sender (BMW)  and vacuum pipe back to the ecu.If you get Dave's Blink head the package should see about 160bhp ish can't remember if you need bigger injectors , look on the MX5 forums it's a very popular swap or contact Motorsport Electronics for advice ECU wise..

That will be a big increase for a nominal outlay I'm sure:yes: we will all give you a hand 

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38 minutes ago, darve said:

your 1.6 ecu won't run a 1.8. the map will be all wrong

please don't drill holes in your flywheel :o these need to be well balanced. I had mine very carefully lightened and balanced by a machine shop @Mark (smokey mow) can you remember what it's called

think I have a stock 1.8 flywheel kicking around (unless I took it to the tip after dropping it on my wheel arch.....) you're welcome to have.

you could use the 1.6 flywheel and clutch with a 1.8 if not running lots of power

you really need to think about going aftermarket ecu if you're going to complete engine upgrades / swap. you could of course install a wiring loom and ECU from a mk2 1.8

It was CTM performance in Dagenham :)

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Rob regardless of what engine you go for you will need to change the ECU if you want to up the performance as the standard ECU can't be tuned it's fixed..

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When at similar stages of tune (standard, induction kit, 4-1 manifold), @Mooch's 1.6 was mostly just a quick on track as my 1.8. The power deficit being offset by the lighter weight. Stick with the 1.6, it's a good little engine :)

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