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Which engine?
Adam - 4/6/12 at 12:32 PM

Hi all

Been a away for a while, kids, mortgages & change of jobs, but now fancy another toy car . I've built an mkindy with r1 engine in about 3 years ago. Great car but want a more usable car engined version. Always loved, and if I'm honest, preferred the mnr. So this is the route I'd like to take. I like the idea of using mx5 parts as had a lots of these in the past and know they are great cars. My aim is to build one, get it on the road and then turbo charge it. The main question is does the mnr take the 1.8 version. Don't seem to be able to find anything on their site and I notice a lot tend to use the 1.6. Would prefer to start with the 1.8.

Would I be financially better off doing a zetec? I see people are turbo charging these too.

Any advice would be much appreciated. can't wait to get cracking. Will be at Newark kit car show without fail

Cheers
Adam

coozer - 4/6/12 at 12:48 PM

Mines got a St170 in it, keep up no problem and now its time for a turbo.. easy cheap way to 350bhp

That should make it quick enough

I'll be at Newark on the mnr stand so come have a look!

[Edited on 4/6/12 by coozer]

Hector.Brocklebank - 4/6/12 at 01:48 PM

I thought the general consensus was that the 1.6 was considered the better bet if you wished to turbo charge the Mazda MX5 motor


You might want to look at some of the MX5 forums, there is loads of info out there.

[Edited on 4/6/2012 by Hector.Brocklebank]

Adam - 4/6/12 at 02:57 PM

I was always lead to believe that the 1.8 was a stronger engine hence turbo would be better on them. Was just wondering if the mnr would take a 1.8?

Cheers
Adam

Hector.Brocklebank - 4/6/12 at 04:11 PM

from my reading in standard trim the 1.6 is the better of the two engines, and that the 1.6 requires less work as its already a low compression engine in its standard state of tune, BBR did a kit that was so good mazda endorsed it as an O.E. bit of kit


linky


and from flyin miata

Mazda MX-5 Miata Eunos 1.6L Turbo Conversion Kit MX5 B6 | eBay

I fancy doing one myself and fitting a body kit to an early MX5 from Tribute Automotive

tribute automotive

Slimy38 - 4/6/12 at 04:26 PM

quote:
Originally posted by Adam
I was always lead to believe that the 1.8 was a stronger engine hence turbo would be better on them. Was just wondering if the mnr would take a 1.8?

Cheers
Adam


I get the impression that the transmission on a 1.8 car was stronger, but the 1.6 engine is a better base for a turbo. But you're talking about pushing an engine to it's absolute limits. Up until that point, the 1.8 should be slightly more powerful from the same turbo kits.

I also seem to remember reading that the Eunos Roadster (the imported Mazda) came with the 1.6 engine but the upgraded diff?

I did read about the various versions from one of the MX5 forums, if I ever remember where I was I'll post the link.

In terms of physical size difference, I was under the impression there wasn't any difference? So whatever car can take a 1.6 can also take a 1.8. Again, this is from my ever-failing memory so I might be wrong.

maccmike - 4/6/12 at 04:49 PM

I also seem to remember reading that the Eunos Roadster (the imported Mazda) came with the 1.6 engine but the upgraded diff?

Thats right but it wasnt standard fit, was on the options list.

BigLee - 4/6/12 at 05:01 PM

quote:
Originally posted by Adam
I was always lead to believe that the 1.8 was a stronger engine hence turbo would be better on them. Was just wondering if the mnr would take a 1.8?

Cheers
Adam


The 1.8 is the same size physically, apart from the diff. The 1.8 diff won't fit in the MNR chassis. The 1.6 diff is very strong as it is. People presume because someone upgraded one once, the standard one must be made of chocolate! I know MX5's running 250bhp on standard diffs with no issue. And that's in a car weighing quite a bit more than an MNR. If you are looking to turbo it, use the 1600. I don't know the scientific reasons as to why, but I am sure there must be something to it as pretty much every boost MX5 I have ever seen is a 1600. The 1800 is just a bored out 1600. Why not turbo it from day 1? I did with mine and it posed no problems with IVA. It certainly made it quieter!
Financially stick with the MX5 drivetrain throughout. No conversions necessary. Just bolt it all down and away you go! If you do go the turbo route, spend time and extra money on the cooling system. Polo rad's aren't good enough if you're boosting it.
Or, buy mine and do what you want with it! No IVA and you could be enjoying it this summer!

Lee

rdodger - 4/6/12 at 05:04 PM

The MK1 1.6 has smaller/weaker gearbox, diff, driveshafts and smaller brakes.

The mk2 1.6 and 1.8 use the same running gear apart from later sports that have even larger brakes.

The compression ratio on both engines 9.5:1 is suitable for turbo or supercharging. The only reason for using a 1.6 might be there used to be more tuning parts available for it. Now that really isn't the case.

A lot of imported cars come with LSD but not all. The recognised better diff is the mk2 Torsen b type diff.

I have and would go for a mk2 1.8 (better head) on the stronger 6 speed gearbox.

Find a well specced mk2 with the gearbox and diff, eather etc. Take the bits you need sell the rest on ebay and like I did get a free donor!

Oh then fit megasquirt and an MP62 Supercharger for 250bhp

BigLee - 4/6/12 at 05:38 PM

quote:
Originally posted by rdodger
The MK1 1.6 has smaller/weaker gearbox, diff, driveshafts and smaller brakes.


The 5 speed gearbox is the same on the 1.6 and 1.8 for all cars from 1990 to 2005. The diff and brakes are indeed smaller, but also lighter. If they work well in an MX5, they're even better in an MNR. I looked at the 6 speed box for mine, but couldn't do it. The 6 speed has its own diff (mk2 Torsen type), which will set you back a fair few quid, and it won't fit the MNR. The other diffs will work but the ratios are wrong. As rdodger suggested, if you can get a car with all these bits, bonus. But they're rare and sought after by the tuning boys 'n girls. You'll just need to grind away part of the diff casing to get it to fit.
Have a look at first350's posts on here. He went the 1800 route and later turbo'd it. A really good build diary too.

rdodger - 4/6/12 at 05:58 PM

Last time I spoke to MNR was advised that they have kits for both 1.8 and 1.6. So you can use either diff.

Fencewrecker - 7/6/12 at 07:52 PM

Hi

I have Chassis 81 which was or is the 1st MX5 chassis made by MNR. It has 1.8 everything, (engine, 5 speed box, diff, brakes) many of you will have seen it if you have been to Stoneleigh or Newark in the last couple of years. It will be at Newark in a couple of weeks. Look for the "Northern Roadsters Club". Weather permitting I will be there both days.

I may up the power but can't see how it will increase the "grin factor", so we will see. Anyway its quicker than most 140bhp at 560kgs, and remember "its not always the size its the pleasure it gives!!!"

Dave