Engine Conversion

[jules]

Great and informed questions piggy.
To start off, I believe the SP motor is no different in internals to the standard BP motor used in all 2001 onwards NB8B's, so finding a motor should be a snack!

The SE which was the last NB8B/C 2003-5 was a slightly different engine with lower compression, no VVT and a smaller turbo than used on the SP.

Yes, you should be upgrading the half shafts and diff (probably to a Mazda, Mazdaspeed, or Guru LSD). While you're at it the 6speed gearbox can be used from the NB8B onwards.

I would think a new ECU is a must.

There are guys here who know heaps more than me about ths stuff, and can point you in the direction of links regarding the best path to take.


Jules

PS: I wouldn't really call what you are going to end up with \"sedate\", but if you insist.

[green_comet]

I think it would be very hard for you to find a SP motor, you would be better off trying to find a halfcut SP, as it would have everything you need to do the swap.. but i think finding a SP halfcut would be near impossible..

If i were you i would go with a SR20, much easier to find, alot more aftermarket goodies for it, and you should be able to get more than enough power out of it.. there is company in Aus that sells the brackets for them to fit into a MX5, i dont have their link but im sure someone here does.

As for diff the 1.6 will pop, your better off going with a 1.8 torsen diff. But that will probably pop too depending on the power you are going to run.

But if its not a huge amount of power your looking for, rebuild the 1.6 you have and turbocharge it. Run a 1.8 diff and gearbox, aftermarket ecu, and it should be fine.

Radiator and brakes will have to be upgraded too.



It really all depends on how much power your chasing.. and how much money you want to throw at it..

[Matty]

The 1.8 engine will bolt up to a 1.6 gearbox (they're the same in most respects).

You'll definitely want a 1.8 diff, which means you'll need the 1.8 driveshaft and half shafts.

You'll probably want 1.8 brakes to slow the thing down and get engineering approval

You might need a 1.8 ECU to get it engineered.

You'll probably want a 1.8 clutch to handle the torque, which means you'll need a 1.8 flywheel to go with it (both mate up to the 1.6 gearbox and starter motor just fine).

If you aren't getting the picture from above: you might as well just buy a 1.8 car to begin with...

[Craig]

If you aren't getting the picture from above: you might as well just buy a 1.8 car to begin with...

Couldn't agree more!

[CT]

If you aren't getting the picture from above: you might as well just buy a 1.8 car to begin with...

Couldn't agree more!

Me three. Just buy and NB8B for $20k and spend another $10k on the turbo kit from Mania and be done with it - or just buy and SE or SP.

Otherwise, you are entering a massive world of pain. BTW, the VVT motor is very difficult to find and 6 speed boxes are rare as rocking horse proverbial at the moment.

[Craig]

On the buy a 1.8L car thing, if you hadn't guessed by the toil that goes into building what i did last time, a big part of the motivation for me is crafting/directing the creation of something as much as i can, aside from that i (call me wierd) like the styling of the 1.6's the most. So as far as it goes, i'll stick with this body

The 94-97 models are the same shape as the 1.6 and have the 1.8 already there. Food for thought!

[Craig]

Yeh I can relate to the 'getting attached' thing...took 2 years of debating to decide to upgrade myself!

[green_comet]

But you have to weigh up the costs. You can stay with your 1.6 or upgrade to a NA8, this is the more sensible option.. Seeing as your going to waste alot of time and money trying to turn your NA6 into a NA8.. Start with a NA8 then do all the mods you want to do, will save you soo many headaches, and soo many dollars..

[irwin83r]

how much power you after btw?

[Boags]

not Really after much power, considering my finace drives it and has no experience with turbos

What an ironic typo...

Anyhow... I like your idea, and most people on this forum (including myself) can't see the reasoning because of the cash involved. However, if that is what you want to do, then here is my advice;

The stock bottom end will take 12-14psi safely for as long as you want if you don't abuse the hell out of it. past 15psi, you need to start thinking about strenthening everything to make sure it lasts/doesn't blow up. From what you have described that you want, the 1.8 with a GT28 or similar sized turbo is the thing for you. Quick spool up, giving you more torque than standard from about 2.5-3Krpm onwards. This setup will be a nice shove in the back at 7-8psi and still safe for your fiance to drive, and then your dual stage boost controller can be used to up to 12psi for when you really want it to get down and boogy. If you build a car thoroughly to handle up to 14 or so psi (brakes, clutch, suspension, radiator/cooling, intercooler, driveline etc.) then it will be bulletproof at 7psi, and a bucketload of fun. If a bucketload isn't enough, you've still got another 7psi...

A lot of people will be very jealous if you do this right, me for one! Good luck, and make sure you keep us updated on what you decide and any progress!

Boags

[NMX516]

Have you considered supercharging?? That would be the way I would go for forced induction these days....

With a decent engine build you could perhaps run higher than std boost from a kit such as a Jackson Racing setup. You're fiance will have a nice even power band to deal with, rather than a peaky turbo arrangement. Superchargers are also more durable than turbos seem to be, and produce far less under bonnet heat. They would also be a less complicated install. Reverting back to standard to sell the car would also be much easier.

just my 2c worth

Keep us posted

[AL]

Hi there piggy. My opinion as follows (can't help myself!) 1- Upgrade to a 1.8 Torsen rear end. 2- Exedy heavy duty organic clutch. (female friendly) 3- PWR radiator (not many options there) 4- AVO manifold and dump pipe (reliable) 5- Garrett GT 28R ball bearing turbo (just my opinion remember!) 6- Ebay intercooler 450x300x76 7- Have it piped up/installed 8- 2.5 inch exhaust 9- keep the AF Meter on the inlet, disconnect the wastgate actuator and you can drive without boost 10- source a good tuner and install a good computer (not going there!) 11- run 2 stage boost control at 8lb =125kw and 12lb =150kw Oh, nearly forgot. Keep the 1.6. Nothing wrong with it

[NMX516]

disconnect the wastgate actuator and you can drive without boost

Disconnect the wastegate actuator and you'll drive with massive boost - once

To run low levels of boost, the wastegate must be open so that the exhaust gases can bypass the turbo. Disconnecting the actuator will keep the wastegate firmly shut, thereby forcing all exhaust gases through the exhaust wheel of the turbo, and subsequently spinning it up to untold (high boost) speeds.

Wastegate actuators are designed so that the boost presure pushing on them opens the wastegate to bleed off exhaust gases destined to pass through the exhaust wheel of the turbo.

[Boags]

Nope, it is the other way around, without the actuator the flap will be open in the turbo and all gases will bypass the turbine.

To attach the wastegate, you close the flap and attach the rod, which holds it shut untill boost forces it open again.

I had a look inside a friends turbo recently when it was off being worked over.

Boags

[sabretooth]

Yeah, he was pretty much right til the part:

Disconnecting the actuator will keep the wastegate firmly shut, thereby forcing all exhaust gases through the exhaust wheel of the turbo, and subsequently spinning it up to untold (high boost) speeds.

.

Disconnecting it will let it flap around open.