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Another Miata engine question

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Joel93 Joel Stephens
Wrexham, Wales, UK   GBR
Hi I'm new to the spitfire but have had 11 mx5s all mk1 and 2 so just saying what iv learnt about them, the 6 speed is made of cheese so I'd leave that alone and it is unnecessary even in a mx5 never mind the lighter spitfire. Engine wise the mk1 1.6 short crank has the crank problem (4 slots on crank pulley) so stay away from them really but a long crank will go forever all 1.8 engines are long crank (8 slots on crank pulley) you can find them with solid engines easy mechanically there bomb proof , but you can get bargains as they rot for fun mk2 and mk2.5 rot most as they changed the chassis rails for crash safety coursing more moister traps this is an un economical repair so they are sold cheap but ideal for you as a doner car. Hope this helped in some way.



Edited 1 time(s). Last edit at 2017-09-22 03:08 PM by Joel93.

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J.P.Rap Avatar
J.P.Rap J.P. Rap
Mount Hope, Ontario, Canada   CAN
1976 Triumph 1500 "Donna"
2007 Ford Ranger
Thanks everyone for your replies. Im gonna pass on the 2002. It doesn't sound like it's worth the trouble. I'm hoping to go have a look at the 92 tomorrow. I was mainly interested in the 02 because it was newer and lower mileage. If the seller of the 92 can come up up with some sort of proof of the (lower) mileage on the drivetrain, I'll feel better about buying that one.


In reply to # 1487071 by clshore
In reply to # 1487046 by J.P.Rap Not familiar with VVT. What is that?
My neighbors kid could help out with Stand alone engine management if it comes down to that. From what he tells me, he's done it a number of times on Nissans.
From what Ive read, the 5 speed is a fairly tight fit. Wondering if there,s much difference in the six speed.

Variable Valve Timing.

The ECU integrates sensor and operational data with a custom developed proprietary OEM algorithm that maps the optimum valve timing for
power, emissions, and fuel economy, to yield a stable, reliable, drivable motor.

Unless your neighbors kid has a access to a dyno, engine telemetry/data capture, an engineering degree, and 6 months to spend,
running an OEM VVT with a standalone engine management system is just not gonna happen.
Thanks for the clarification Carter. My neighbor owns a body shop and his son works for him. He builds a lot of custom cars and the last time we talked he was saying there are computers available on the internet for replacing OEM computers when swapping out engines like this. I guess that's not what you were talking about in your previous post.
On a side note, I expect to get my engineering degree three years from now so maybe I'll think about it then.grinning smiley

Cheers



"In this world, you must be oh so smart, or oh so pleasant. Well, for years I was smart. I recommend pleasant." Elwood P. Dowd

tightapex Avatar
tightapex Greg Bailey
Gilroy, California, USA   USA
Good luck on whichever engine you choose, J.P. I know if I was leaning toward a Miata-based engine swap, my first choice would be a 1.6L with a five-speed. As for the short nose crank issue, it's typically confined to the '90 and early '91 models. As mentioned earlier, this link is a great article:

https://www.miata.net/garage/crankshaft.html



Edited 1 time(s). Last edit at 2017-09-23 12:11 PM by tightapex.

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Manana Avatar
Manana Steve Wten
Thornhill, Ontario, Canada   CAN
JP

One of the best things about having a donor car is that ALL of the EI and EFI stuff goes with it. No mucking about with Mega Squirt or any other aftermarket stuff.

There is another guy (Dave, sorry I can't reply directly right now, away from my email for a few more days) who sounds like he's making good progress with a 1.8. I haven't had a chance to check out his stuff on Grass Roots yet, but I'm certain it's worth a read.

I have a decent schematic for the wiring that I'll put up on my site soon. Will advise.



Steve
http://stevew10.wix.com/spit16

clshore Carter Shore
Beverly Hills, Florida, USA   USA
In reply to # 1487362 by Manana JP

One of the best things about having a donor car is that ALL of the EI and EFI stuff goes with it. No mucking about with Mega Squirt or any other aftermarket stuff.

There is another guy (Dave, sorry I can't reply directly right now, away from my email for a few more days) who sounds like he's making good progress with a 1.8. I haven't had a chance to check out his stuff on Grass Roots yet, but I'm certain it's worth a read.

I have a decent schematic for the wiring that I'll put up on my site soon. Will advise.

That's great, until you encounter a newer car where everything has been integrated into the OEM ECU.
What, no seatbelt, passenger seat, or airbag sensors in your Spitfire?
No vehicle stability, no ABS, no door open, no gas tank cap open, no front/rear windshield defogger?
No VSS speed sensor to lock the doors above 5 MPH?
No collision alert, or ride stability, or WB02 sensors?
BTW, all modern ECU are now encrypted and cannot be accessed to disable or modify anything unless you have the special dealer machine
and the secret handshake to operate it.

Welcome to Skynet.

J.P.Rap Avatar
J.P.Rap J.P. Rap
Mount Hope, Ontario, Canada   CAN
1976 Triumph 1500 "Donna"
2007 Ford Ranger
Thanks for all the replies guys. I haven't been able to get hold of the guy selling the 92 yet. Hopefully this week. I'll keep you posted.



"In this world, you must be oh so smart, or oh so pleasant. Well, for years I was smart. I recommend pleasant." Elwood P. Dowd

dherr2 Avatar
dherr2 David Herr
Adamstown, Maryland, USA   USA
1972 Triumph Spitfire MkIV "Rat Rod"
That is why you have to do your research carefully and select the right engine donor. Agree completely that some of the newer cars and their ECU's make it almost impossible to use them for a swap unless you replace the ECU with a megasquirt or other custom solution.

For the Miata 1.8 swap, I went with the 1998-2000 BP-4W and 6 speed transmission. The 6 speed was part of the package, probably could have just used a 5 speed, but making it fit was no more work than the 5 speed. You do have to relocate the emergency brake further back, but my trans tunnel needed fixed anyway. Back to the engines, the 1.8 engine starting from 1993 is a good choice, simpler ECU and good power. The "best" engine of the 1.8's is the 1998-2000 BP4W series as they had more power (140 HP), forged internals and are preferred by the tuner experts for turbocharging. While they are ODB2, they are much simpler than the later cars which have VVT and are not worth the extra work involved. You can use the stock ECU for this engine series for an engine swap.

My build is documented on the Grassroots site here Spitfire Miata build

Working now on the Subaru rear LSD Diff install, will be posting pictures soon.

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Manana Avatar
Manana Steve Wten
Thornhill, Ontario, Canada   CAN
There's the Dave I was talking about! Nice to see your progress Dave.

Carter, seeing as I was referring to the first gen Miata it is great. In all honesty I'm not even sure the newer vehicles would be that big a problem, unless you wanted all the fancy stuff like auto-locking doors to actually work. I don't think leaving those items out will make a difference to engine management.

Dave, as mentioned on my site, I also was enticed by the 1.8 and 6-speed, however after learning that the block was about 3/4" longer and seeing the shifter location on the tranny would be a massive job to move forward I went with the 1.6. I'd like a few more ponies, but wasn't willing to sacrifice what I thought was an awesome shifter location.

I did a quick job on documenting my electrics including the wiring diagram here....
http://stevew10.wixsite.com/spit16/electrical
Will eventually add more, but wanted to get that up to help out anyone interested.

Keep it up Dave.



Steve
http://stevew10.wix.com/spit16

RobTAR Robert I
Seattle, WA, USA   USA
In reply to # 1500732 by Manana There's the Dave I was talking about! Nice to see your progress Dave.

Carter, seeing as I was referring to the first gen Miata it is great. In all honesty I'm not even sure the newer vehicles would be that big a problem, unless you wanted all the fancy stuff like auto-locking doors to actually work. I don't think leaving those items out will make a difference to engine management.

Dave, as mentioned on my site, I also was enticed by the 1.8 and 6-speed, however after learning that the block was about 3/4" longer and seeing the shifter location on the tranny would be a massive job to move forward I went with the 1.6. I'd like a few more ponies, but wasn't willing to sacrifice what I thought was an awesome shifter location.

I did a quick job on documenting my electrics including the wiring diagram here....
http://stevew10.wixsite.com/spit16/electrical
Will eventually add more, but wanted to get that up to help out anyone interested.

Keep it up Dave.

I found the 1.6 to be the most fun out of all the Miatas, you really have to beat on it to wring any performance out of it. I have driven all four generations and the MSM.

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dherr2 Avatar
dherr2 David Herr
Adamstown, Maryland, USA   USA
1972 Triumph Spitfire MkIV "Rat Rod"
Thanks Steve, your work has been an inspiration for my project and your web site a huge source of information. The length of the 1.8 has not proven to be an issue as the same frame cuts and modifications are necessary for either engine. I have about an inch clearance from the bonnet, so all good in that regard. I am curious about your concerns on the extra length of the differential as I have mine installed now and have mocked up the driveshaft with a piece of PVC. The angles appear good (have not measured it yet, but looks pretty minimal). What exactly am I looking to avoid as both seem to be pretty straight shots.


Manana Avatar
Manana Steve Wten
Thornhill, Ontario, Canada   CAN
Hey Dave sorry about the delay getting back, out of country for a few days with poor internet.... Looking at that image with the PVC in there I don't think you will have any issues; your geometry looks different than mine did (although not really sure how, maybe your engine is lower or you have set your engine/diff at more of an incline).

I have some more details on the General Fitment page on my site about half way down.... http://stevew10.wixsite.com/spit16/general-fitment-and-functional-concerns

Reader's Digest version is that, as I'm sure you know, one wants both Tranny Output Flange and Differential Input Flange to be parallel on all planes. It can (and should) be offset in height, but not too much, to induce a 1.5 degree delta for the propshaft. In my case, with the short little Spit Differential and engine mounting height I ended up with a 6 degree delta (at both ends of course). My reading showed that 3 degrees is about as much as one should go with U-Joints, however, many have gone further without any issues.

In my case, increasing the length of the differential would make the propshaft shorter of course, and keeping the same heights for each flange would result in a greater angle for the shaft. At 6 degrees mine is working out fine, but I'd be concerned with more than that.

Again, that image makes it look like you are doing well.

That written, I'm curious what angle your engine and diff are at? From my measurements Mazda put the 1.6 engine/tranny at about 1.5 degrees aft tilt which was important for tranny lubrication if I recall (and who knows what else). I didn't want to change the diff angle (bearing lubrication etc) but figured if I had to to make it work, a little wouldn't hurt (didn't need it in the end). Your pinion bearing is pretty far forward, so any change in incline of the diff may starve it of lubrication. Haven't read of anyone with that issue though, so it may be insignificant.

Thanks for the kind words, you're doing a bang up job there, looking forward to learning more and improving mine with some of your ideas.



Steve
http://stevew10.wix.com/spit16

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