Is it worth replacing the rings?

[offroading.net]

Have a 1.6 that needs new piston rings (result of having water sat in the bores after HG failiure before i got it)
Now is it worth the effort of doing the work (would do it myself) on a 110k mile engine or should I just get a low milage motor from a breakers and swap it out? Just that the new rings may end up new pistons and a rebore if the pitting is too bad and more ££ on an old engine

[MX-5 Lazza]

A replacement engine will probably cost no more than new rings and all the other parts you'll find you need to replace while you're in there.

[franv8]

Whip it apart and get the measuring sticks out to decide if you need the new parts?

A second hand motor can be a risk if bought hastily...

[MX-5 Lazza]

The engine has to come out before you can get to the rings. If I had to do that I wouldn't bother refitting a 110k miles engine that has already suffered HGF unless I replaced the pistons, rings & bearings along with any other parts that might be worn. It would be cheaper to replace and wouldn't cost too much more to fit a 1.8 engine

[offroading.net]

thing is the engine has a brand new head and water pump on it (ebay bargains) so could just be a ring swap or a load of hassle.
TBH I am thinking of getting another engine and supercharging it. BUT it is an auto which I want to keep, will a manual engine be the same as an auto (apart from TC/flywheel differences?

[MX-5 Lazza]

The auto engine is different from a manual engine in that it has lower compression and softer cams which give less peak power but more torque at lower revs which better suits an auto-box.
If you are considering supercharging, the auto engine (with a manual head or cams from a manual) is actually a good choice due to the low compression but you will also want to be sure the engine is strong.
Don't take this as gospel though. The lower compression is a fact but I'm only 75% sure about the cams

[franv8]

Might be worth posting on MX5ocforum lookng for the specific answer - there's at least 1 Mazda tech on there.

[offroading.net]

MX-5 Lazza said:

The auto engine is different from a manual engine in that it has lower compression and softer cams which give less peak power but more torque at lower revs which better suits an auto-box.
If you are considering supercharging, the auto engine (with a manual head or cams from a manual) is actually a good choice due to the low compression but you will also want to be sure the engine is strong.
Don't take this as gospel though. The lower compression is a fact but I'm only 75% sure about the cams

Yep, the pistons are more dished on an auto and the cams give more torque but more power, just wondered if the block is different. The manual head on the auto make a big difference top end but you lose bottom end especially in 1st.
Think the plan will be find a good low milage auto engine and put my new head on it after a bit of work on it then sort out the supercharger.

Edited by offroading.net on Wednesday 22 October 09:23

[MX-5 Lazza]

Sounds like a good plan. If it was me I'd fit the manual cams. If you're fitting a supercharger, mid-range torque won't be a problem

[offroading.net]

My new head is a standard manual one, with the better cams, new old stock via ebay for £100, bargain, will stick it on whatever engine I get as it has only done 400 miles