Decisions on engine swap?

Skilfil · Post by **Skilfil** » Mon Oct 31, 2011 1:03 pm

I bought a 1990 NA MX-5 3 weeks ago, first time owning an MX-5 and I don't regret it one bit at all.

I'm looking at potential power upgrades for it next year as it has the 1.6 in it at the moment, its fun as it is but I'd like to do some track work and pursue a little power.

At the moment I'm tossing up between a 2.5L Mazda V6 the KL-ZE, or the 1.8T out of a GTX Familia. An engine swap is a big project yes, but at the moment I'm weighing my options. Somewhat leaning toward the GTX engine as it would offer more room to play around being turbo.

Just wondering what do you guys think? I've come from Volkswagens so any advice is appreciated. Thanks.

WideOpenThrottle · Post by **WideOpenThrottle** » Mon Oct 31, 2011 3:28 pm

If the Gtx is a 1600 like what i was going to put in then i needed to change the sump,engine mounts & brackets,adapter plate for the bell housing,cut into the firewall for the distributor,re-work the Turbo & exhaust manifold to suit rear drive,change over the ecu & loom..to name a few so i didnt do it-just used the turbo & intercooler.- i think the 1800 GTX must be similar & i know they have been done. A lot of the guys on this forum stick with the existing motor, turbo them plus with decent engine management & they get little rockets!

Cant help with the V6-might as well do a V8!!

sprsta · Post by **sprsta** » Mon Oct 31, 2011 4:03 pm

A turbo setup on the 1600 you have will at least double the power you are currently making

If you want to go 1800 be sure to get an mx5 one not one from a familia or all you will be able to use is the long block

Make sure you get some engine management and larger injectors
when turboing an mx5. A second hand link ecu can be had pretty cheaply these days

IIRC mazdaspeed did a KL transplant in japan in the 90s and gave up half way through it was too hard you may as well do a V8

Skilfil · Post by **Skilfil** » Mon Oct 31, 2011 4:25 pm

Ah hadn't done too much looking into the GTX motor, thats off the list then. So then a 1.6 turbo or 1.8? Whats the benefits/strengths between them? Is there any real reward from the work involved in putting a 1.8 in or is that easily negated with spending that effort modifying a 1.6?

I know in the Ford Laser/Mazda Familia motors the 1.8 handles boost better as most of the internals etc come a bit beefier. I imagine it wouldn't take much to get an MX5 to really go, I'm also weary of the 1.6 gearbox and diff as Americans seem to bag on them a bit.

WideOpenThrottle · Post by **WideOpenThrottle** » Mon Oct 31, 2011 4:54 pm

If i were to do it all again i would go for the NA 1800 complete car & then turbo it as everything is certainly a lot beefier!

SLYDIT · Post by **SLYDIT** » Mon Oct 31, 2011 5:34 pm

the engine is the LEAST of your worries..they are pretty bullet proof up to about 12-14PSI UNMODIFIED and that is a LOT of horsepower.

the diff and brakes are what will let you down with the turbo going on...
the best solution is this:

Custom turbo system on the 1600 with a HD clutch and megasquirt ECU controlling everything. Get yourself some 440cc Subaru injectors from a 2000+ WRX.

When the diff blows upgrade it to the 1800 size and upgrade the brakes to 1800 size also.

the 1800 engine wont give you any real world advantage in terms of Cost /performance over the 1600. A local club guy put a GTX engine in his and it was a lot of shaggin around. You are better to keep the 1600 and just make sure you have good engine management and tuning.
lower compression in the GTX just means its less likely to get detonation over the high compression engine BUT if you tune it right the high compression 1600 and 1800 engines are just as reliable

Gravelben · Post by **Gravelben** » Mon Oct 31, 2011 6:22 pm

The straightforward option for power gain is definitely turbo or supercharge the engine in it, tried and tested with plenty of knowledge around on how to do it properly.

That said, KL-ZE swaps have been done and personally I think it would suit the MX5 character perfectly, a nice revvy sweet-sounding 200hp V6. Pretty sure its the same weight or marginally lighter than the original motor too.

There are a few vids on youtube of a bloke in the states who has a KL-DE with bike thottlebodies etc in his Miata, sounds very tasty!

Skilfil · Post by **Skilfil** » Mon Oct 31, 2011 6:30 pm

So what kind of turbos are you guys using to get 200 hp straight out of it? I know the 1.6 is just shy of 100 hp stock so thats a fairly big increase.

Brakes were on my list as it is due to owning a Mk3 Golf GTI before this, it had HUGE brakes and I got very used to them. They'd lift you off the seat and I'm not small, then to the MX5 which needs new pads and fluid it doesn't stop too quickly.

So the gearbox itself isn't a problem? I like the short ratios in it, but was looking at the possibility of a 6 speed. I'm happy to keep the standard 1.6 box if its sufficient however.

Sorry for the 21 questions, I just like to do my homework before I start swearing at things that don't fit.

Skilfil · Post by **Skilfil** » Mon Oct 31, 2011 6:35 pm

Gravelben wrote:The straightforward option for power gain is definitely turbo or supercharge the engine in it, tried and tested with plenty of knowledge around on how to do it properly.

That said, KL-ZE swaps have been done and personally I think it would suit the MX5 character perfectly, a nice revvy sweet-sounding 200hp V6. Pretty sure its the same weight or marginally lighter than the original motor too.

There are a few vids on youtube of a bloke in the states who has a KL-DE with bike thottlebodies etc in his Miata, sounds very tasty!

A few have stated the KL-ZE to be lighter than even the 1.6 due to the 1.6 being an iron block and the KL-ZE an alloy block.

If you search KL V6 Miata on Youtube, its a blue one with onboard video. Thats the one that made me interested in the V6, love that noise..

SLYDIT · Post by **SLYDIT** » Mon Oct 31, 2011 7:43 pm

the weak links in the mx5 drive train when turbo'd in order of weakness are:

Clutch
diff
gearbox
conrods

Forget using a 1600 clutch of any sort..the "heavy duty" clutches in 1600 size that can handle the turbo's torque are a pain to drive on a regular basis....better to get a heavy duty1800 flywheel and clutch which will hold the power and your nana could drive it.

gearboxes are pretty strong (they are after all a series 5 RX7 box ) when horsepower gets insane the gearbox casing flexes and you strip gears. The 6 speeds are bullet proof

for turbo sizing you need a turbo from a 2 liter turbo such as a garret GT25 from an SR20 or an RB20 turbo... I am using a VF10 turbo from an old shape Legacy GT. The turbo is essentially a GTX turbo but it has a much bigger compressor wheel for more HP per pound of boost..

A wrx turbo is a bit small in real terms. it'll boost really hard down low but youll need to high boost level to get the HP out of it..High compression MX5 engines like turbos that are relitively high flow per pound of boost...hence the GTX and WRX turbos are a bit small.

as a guide my Turbo'd (142RWKW) mx was G'techd at 0-100 in 5.8 seconds on a pretty crappy road and a bit of wheel spin...the GTX powered car running double the boost of mine and 195RWKW did it in 5.2 seconds

Skilfil · Post by **Skilfil** » Mon Oct 31, 2011 8:45 pm

Ah well I don't think I'll be going for insane horsepower, probably around the same figures as you've achieved. Are you still using the Izuzu Intercooler from the Car Domain page? I'd like to retain the normal front bumper, don't want to advertise anything.

It sounds like the 1.6 turbo is the simplest and least stress free way to go, this will all go into action at the start of next year as I'll be in employment then, need another car to drive while I'm playing with this one.

SLYDIT · Post by **SLYDIT** » Tue Nov 01, 2011 7:31 am

yes still using the isuzu intercooler...not the flashest thing on the planet but it gets the job done.

In reality there is LOADS of room in the nose for an intercooler. any of the popular smaller ones from repco etc will fit in there. the plumbing from IC to the throttle body is easy (2.5") but the turbo to IC is pretty tricky with power steering and coolant lines getting in the way. there are various work arounds for those though...

just DO NOT buy one of those turbo manifolds off trde me...theyre crap

Post by **jif** » Tue Nov 01, 2011 7:38 am

just one thing I would add ... miataturbo.net

[Posted via external email]

WideOpenThrottle · Post by **WideOpenThrottle** » Tue Nov 01, 2011 8:20 am

Even with the small 1600 Gtx Turbo & intercooler i put on my car with its basic engine ecu-Man! what a difference the car is,! it makes our other NB 1800 feel like a gutless wonder now!..Car mods are always gonna make you curse but you just gotta do it!

Skilfil · Post by **Skilfil** » Tue Nov 01, 2011 12:59 pm

Ah that Miataturbo link is going to take up hours of my time I see.. Thanks. Well now I've got all this information, onto the next thing. Need to do an oil change, not sure whats in there atm (no sticker or documentation) and I want to shut the horrendous ticking up, what grade/brand has worked in the past for you guys with a 1.6?

punkoutnz · Post by **punkoutnz** » Tue Nov 01, 2011 2:18 pm

One piece of advice I can give you is DO NOT cut corners. I've just spent the last six months fixing up a half pie turbo conversion on my car. It ran for nearly a decade on the old setup but it was starting to reveal its shortcomings.

Buy braided lines and the right fittings, they are expensive but they will last (I spent about $750 on all mine!) from a reputable place (Greenlane Speed Shop or Cardwells are two good places).

Buy a quality turbo, not a chinese replacement, even a good condition second hand garret will long outlast a chinese knockoff from Trademe.

Drill the oil return into the sump below the turbo, don't use the factory bung on the other side, this was one of the biggest annoyances of the setup my car had, it made the engine bay messy and brought with it all sorts of problems.

If you find yourself hitting a snag, ask for help! There's so many knowledgable people on here and abroad that will be more than happy to offer you advice.

Gravelben · Post by **Gravelben** » Tue Nov 01, 2011 5:32 pm

Skilfil wrote:Need to do an oil change, not sure whats in there atm (no sticker or documentation) and I want to shut the horrendous ticking up, what grade/brand has worked in the past for you guys with a 1.6?

With the standard MX5 I used 10w40 Castrol Magnatec, with turbo cars I always go for a full synthetic though.

sprsta · Post by **sprsta** » Tue Nov 01, 2011 5:55 pm

just a heads up with miataturbo.net be sure to read and search before asking ANYTHING!!!

Skilfil · Post by **Skilfil** » Tue Nov 01, 2011 5:57 pm

Ah right they jump down your throat for not using the search function?

I'll give 10w40 a try.

SLYDIT · Post by **SLYDIT** » Tue Nov 01, 2011 7:41 pm

YES miata turbo forum guys will Burn your ass for not searching...theres a hundred of guys like you asking the exact same newbie questons on there and it gets pretty old FAST.
Dont take it the wrong way they are just not tolerant of new guys like we are here in friendly ol NZee.

the ticking can usualy be solved by an oil change....some cars like shell some will like magnatec etc etc.what wrk s on 1 car wont necessarily work on another.
I ran magnatec in mine till i went turbo, now i run full synthetic

brownie · Post by **brownie** » Tue Nov 01, 2011 11:53 pm

Mazbits in Auckland have a 1800 Turbo front half conversion ,That would be a good place to start has it will have every thing you need for the Turbo conversion including wiring and ECU,If wanted to get carried away with it you would get your car going with it and then refresh the motor so you know you will get a good run out of it,
I have seen photos of it when they first got it,Bloody nice bits in it.
Jason there will be able to help you.
Also talk to Wade at Cascade Car wreckers .He worked there when it came in from Japan and will have good info on it as he arranged the half to come in.
They have had it awhile so might be looking to do a sharp deal on it.

Skilfil · Post by **Skilfil** » Thu Dec 08, 2011 10:17 am

Was going to make a thread but thought I'd just post here, at pick a part a few weeks ago a friend was checking out a Mazda while I was off wandering around. He thought it was a bit strange, it was a RWD V6. Mazda Sentia, same 2.5 as the FWD versions in the other cars.

Just thought I'd let people know in case anyone was interested in a V6 MX5, but didn't want the FWD headaches. I wonder how much easier it is to stick in the RWD configured V6?

http://en.wikipedia.org/wiki/Mazda_Sentia

Timmo · Post by **Timmo** » Sat Dec 10, 2011 6:57 am

The Sentia/929 also came with a 3l variant as well. I owned a 2.5 model for a short time....big car + small engine = slow and thirsty. As an engine they are nothing special.

Growler · Post by **Growler** » Mon Dec 12, 2011 12:00 pm

SLYDIT wrote:the weak links in the mx5 drive train when turbo'd in order of weakness are:

Clutch
diff
gearbox
conrods

Forget using a 1600 clutch of any sort..the "heavy duty" clutches in 1600 size that can handle the turbo's torque are a pain to drive on a regular basis....better to get a heavy duty1800 flywheel and clutch which will hold the power and your nana could drive it.

gearboxes are pretty strong (they are after all a series 5 RX7 box ) when horsepower gets insane the gearbox casing flexes and you strip gears. The 6 speeds are bullet proof

for turbo sizing you need a turbo from a 2 liter turbo such as a garret GT25 from an SR20 or an RB20 turbo... I am using a VF10 turbo from an old shape Legacy GT. The turbo is essentially a GTX turbo but it has a much bigger compressor wheel for more HP per pound of boost..

A wrx turbo is a bit small in real terms. it'll boost really hard down low but youll need to high boost level to get the HP out of it..High compression MX5 engines like turbos that are relitively high flow per pound of boost...hence the GTX and WRX turbos are a bit small.

as a guide my Turbo'd (142RWKW) mx was G'techd at 0-100 in 5.8 seconds on a pretty crappy road and a bit of wheel spin...the GTX powered car running double the boost of mine and 195RWKW did it in 5.2 seconds

Thats some very good info there. In fact this forum is full of good useful information. Do we need a sub-section that has all of this relevant information so its all in one place? What are your thoughts?

Gravelben · Post by **Gravelben** » Mon Dec 12, 2011 7:42 pm

Timmo wrote:As an engine they are nothing special.

KL-ZE or KL-DE? Same block, different heads, very different engine (200 vs 160 bhp)