[rusEfi] Hunchback 1991 Miata NA/NB2 rusEfi official racecar #20

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Re: 1991 Miata #20 Hunchback

Post by kb1gtt »

I'd bet you could get more in the garage if you put them on end. Kind of like books on a shelf.
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Re: 1991 Miata #20 Hunchback

Post by AndreyB »

kb1gtt wrote:Kind of like books on a shelf.
That's a plan! I can sort them by color! :)

I have to confess - this one would avoid my garage, the plan is to take it apart at my racing partner's shop.
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Re: 1991 Miata #20 Hunchback

Post by kb1gtt »

You should consider getting your licence plates with Dewey Decimal numbers. It would make it easier to find your car when you loose it in your garage :)
https://en.wikipedia.org/wiki/Dewey_Decimal_Classification
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Re: 1991 Miata #20 Hunchback

Post by stefanst »

Are the subframes and control arms usable?

NB front subframe has been improved over the NA version. Gives you more caster and lowered mounting points for the lower control arms afaik. So if you can keep that and throw it on the racecar- I believe that swap should be possible without too much pain, especially if you're swapping engines anyway.

Rear subframes have not changed afaik.
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Re: 1991 Miata #20 Hunchback

Post by AndreyB »

stefanst wrote:NB front subframe has been improved over the NA version. Gives you more caster and lowered mounting points for the lower control arms afaik. So if you can keep that and throw it on the racecar- I believe that swap should be possible without too much pain, especially if you're swapping engines anyway.
http://www.miata.net/garage/compatibility.html is our new favorite page. The only issue with NB is that we would not have spares and would not have an option to beg/borrow/steal from other NA at the track. But yes tempting :) We night try NB sub-frame with NA everything.
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Re: 1991 Miata #20 Hunchback

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Re: 1991 Miata #20 Hunchback

Post by stefanst »

russian wrote:[...]

http://www.miata.net/garage/compatibility.html is our new favorite page. The only issue with NB is that we would not have spares and would not have an option to beg/borrow/steal from other NA at the track. But yes tempting :) We night try NB sub-frame with NA everything.
The only difference is the subframe afaik. So all the control arms etc. are the same. If you have an NB subframe it would be foolish not to use it!
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Re: 1991 Miata #20 Hunchback

Post by AndreyB »

Learned a $100 lesson yesterday: most of the turbos spin clock-wise so the nut has the unusual left-hand thread :(

At least https://www.amazon.com/gp/product/B01I5NEA40 worked great, totally recommend the tool.
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Re: 1991 Miata #20 Hunchback

Post by stefanst »

If you're taking the turbine and compressor assembly (CHRA) apart, do you have a way of getting it balanced after re-assembly?
I believe they're balanced together as an assembly, but not quite sure...
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Re: 1991 Miata #20 Hunchback

Post by AndreyB »

I am assuming that as long as I mount the cold wheel at the same angle on the shaft the wheels/shaft stay balanced?
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Re: 1991 Miata #20 Hunchback

Post by stefanst »

I'm assuming the same. But then my assumptions are not always to be trusted....
I'm sure we can google us an answer :)
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Re: 1991 Miata #20 Hunchback

Post by AndreyB »

Since I am back on square one. What are good junk yard turbo options from OEM US market applications? I've tried googling but a lot of older threads are referencing dead pages. Also a lot of pages are referencing crazy nissan or toyota options while saab or volvo is probably much more realistic.

So do we know any specific good donors for a turbo on a 1.6 engine? I am going to some place in Queens on Saturday they claim to have some turbos starting at $75.
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Re: 1991 Miata #20 Hunchback

Post by stefanst »

Discarded Nissan Silvia turbos are the holy grail of used turbos for Miatas. The bigger, the better of course :)
TD04s, as they're used on Saabs and Subarus also seem to make decent power.

Some Miata guys also take the stock Mazdaspeed turbo (IHI I believe) off to replace it with something bigger- that would also make a nice option for you.

Mitsu Eclipse turbos should do.

Anything that runs a 4 or 5 cylinder and gets around 200hp should work in a track car. So what if it doesn't spool below 4000rpm- you won't ever drop rpms that low anyway.

No diesel turbos for track use AFAIK, since they're not spec'ed for the temperatures coming off the good old gasoline engine.

All the newer ones that are integrated in the exhaust manifold are out of question for obvious reasons. Or maybe create one hell of a LeMons-ish Frankenstein setup?

More TD04 info than you'd ever want: http://team-rs.ru/technical/images/TD04_turbos.pdf

EDIT: It looks like the easiest would be a Volvo or Saab turbo- they seem to have standard flanges. Subaru and Mitsubishi use weird flanges. The TD04-15G seems to be the best suited, but similar sized ones should work pretty well as well. Check here for size info: http://megamiata.blogspot.co.il/ scroll almost all the way to the bottom. Maybe print that and take it with you.....
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Re: 1991 Miata #20 Hunchback

Post by AndreyB »

Got these three for under $200 total, now need to choose one.

option #1 Saab 9-3
least play on the wheels but most oil in the intake

77-11955 060 KN2 looks like TD04L-14T 2005 2.0T Saab HO 210ps
with blow off/air bypass valve
with wastegate
2005_saab_9_3.jpg
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option #2 Volvo 2.5 XC70
TD04L-14T
most shaft play - I think I head oil chomping noise
with blow off/air bypass valve
with wastegate

both volvo and saab say TD04L-14T but different exhaust flanges, I assume similar or same internals?
2004_volvo_xc70.jpg
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option #3 1995 Eclipse AT
A/R .48 M10 Garret
MHI187910
smaller than the one I've destoyed, looks like AT is the smaller version
with wastegate, no blow off
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1995_eclipse_at_2.jpg
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PS: flange source
http://www.atpturbo.com/
http://www.genuinesaab.com/catalog/product_info.php?products_id=646
http://www.genuinesaab.com/catalog/product_info.php?products_id=621
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Re: 1991 Miata #20 Hunchback

Post by Somebody »

Just my .02 to put into this. For the car and its goal, the faster spooling turbo will be our friend. The Mitsubishi would be the way to go. It will fizzle out on the top end which in turn makes NJMP an issue, however for Thompson and NHMP it is the perfect match to dig out of the corners better. Although a TD04 setup would be more ideal for top end, some of the nasty traits of mid corner balance of power can come into effect, ie. Spinning the car with a crazy powerband.

The NB subframe is a must, if we break it, then there are more worries then trying to find replacement parts. We would have a pretty crashed up car. It will only benefit the NA chassis.
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Re: 1991 Miata #20 Hunchback

Post by stefanst »

Nice collection!

I'm running a T28- comparable to a Garrett GT2560 in today's nomenclature I believe. Near as I can tell, this turbo is bigger than any of the ones you've pulled. I don't have any problems with sudden onset of power. Keeping it above 4000rpm on the track means that full boost is always available and therefore predictable. But you do have to be more careful with the throttle on track-out than on a naturally aspirated Miata :)

All that being said, I'd go with the Saab turbo if it's easily implemented. Should get you over 200hp and spool nicely. Also less shaft play than the Volvo means better reliability. You may be able to swap turbine housings if needed. Not sure which flange is more easily implemented. I wouldn't worry about the oil on the compressor wheel - that comes from the engine via crank-case ventilation and is indicative of bad piston rings- not a bad turbo.
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Re: 1991 Miata #20 Hunchback

Post by kb1gtt »

Do I see any with coolant lines? I think I only see oil lines.

Water cooled turbos are good for race applications. If you stop your engine after a race you will want to let it run idle for a couple minutes to cool down. If you don't it's common that the engine heat will burn the oil inside the turbo causing coking to happen on the bearing which results then starves the bearings of oil, and causes damage. A water cooled turbo helps avoid that kind of heat build up issue.

I seem to recall some years ago when I had a turbo rebuilt, that the shaft bearing had a tolerance of 0.0001 inches. Very tight tolerance. If you can feel shaft play, you might have toasted bearings.

Lemons car, why not put all the turbos on it, then pick and choose how much boost each one makes?
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Re: 1991 Miata #20 Hunchback

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Re: 1991 Miata #20 Hunchback

Post by stefanst »

Depending on your turbo you may also need an oil-restrictor. Also:
Oil connectors/fittings on the turbo itself
Air filter & piping
Intercooler + piping
BOV or recirc valve
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Re: 1991 Miata #20 Hunchback

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stefanst wrote:Depending on your turbo you may also need an oil-restrictor.
http://www.ebay.com/itm/310491456415 just ordered - AN 3 to M10x1.5 Metric Stainless Steel Brake Car Fittings Adapter 3/8x24 UNF 3AN - small enough hole to act as a restrictor?

@ has dropped some air side parts, see you next weekend :) I'll start removing the exhaust manifold.
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Re: 1991 Miata #20 Hunchback

Post by AndreyB »

We are starting to get ready for the 2017 racing season. If we do not use rusEfi at the NJMP race in May somebody please punish me in some humiliating way.

Since I do not know much about cars my role on the team is finding parts cars & selling parts to produce free spare/upgrade parts. On the picture is a non-running 2002 without front panels I've scored today. Originally I was shopping for a 2002 ECU with a matching key, the guy mentioned he would love to sell the whole car... He did not realize what a gem he had - it is an LSD diff and under the wooden aftermarket shifter lies a 6-speed transmission!
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Re: 1991 Miata #20 Hunchback

Post by AndreyB »

Also driving this lifted 7.3 F250 was an interesting experience.

After first two minutes I was panicking and considering calling Ethan to say I am not capable. After half an hour I've stopped sweating.

After 2.5 hours of F250 getting back into my SUV (body-on-frame, leaf spring read suspension) felt pretty much like driving a Miata on a race track.
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Re: 1991 Miata #20 Hunchback

Post by tomiata »

Do you still have a 1.6L engine in this car? What do you have set for TS Trigger Angle Offset? Is that the same setting as set_global_trigger_offset_angle?

I discovered my timing was way off on my '90 Miata. I checked with the timing light and it looks like 10 or 12 degrees off. 10 degrees on the ignition table was more like 20 on the timing light. It seemed to be doing fine when got it running months ago, but I noticed some knocks at high load and low rpm recently.
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Re: 1991 Miata #20 Hunchback

Post by AndreyB »

Yes still have 1,6 for a month or maybe more. I can verity timing with set engine_type 41 which I believe is shared between you and me,
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Re: 1991 Miata #20 Hunchback

Post by stefanst »

tomiata wrote:Do you still have a 1.6L engine in this car? What do you have set for TS Trigger Angle Offset? Is that the same setting as set_global_trigger_offset_angle?

I discovered my timing was way off on my '90 Miata. I checked with the timing light and it looks like 10 or 12 degrees off. 10 degrees on the ignition table was more like 20 on the timing light. It seemed to be doing fine when got it running months ago, but I noticed some knocks at high load and low rpm recently.
There's several reasons why your timing may be (or seem) off.
1) The Trigger Angle Offset was wrong. If so, fix it and move on with live
2) There's something mechanical going on with your engine

2a) On older engines the outer ring on the crank pulley can come lose and start slipping. This will lead to wrong indication of timing. The easiest way to check is the "stick in the sparkplug hole" method. Remove sparkplug on cyl. #1 and put a "stick"- for example ratchet extension in there. Crank the engine by hand and find TDC (where the stick is at its' highest). Verify that your timing mark is on 0deg.

2b) AFAIK the cam sensor on NA engines can be adjusted. If it's out of adjustment, your timing will also be off. You can verify this by checking the timing for the stock ECU. Method cna be found here: https://www.miata.net/garage/ignition.html#timing

One note: It's a little hard to find, but rusefi can be switched to fixed timing- that makes it easier to adjust timing and figure out latency.

The mode can be set under "base engine settings" and set "timing mode" to "static". Set static timing at 10deg and verify with a timing light at different rpms.

Also: please post your timing table!
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Re: 1991 Miata #20 Hunchback

Post by tomiata »

stefanst wrote:
There's several reasons why your timing may be (or seem) off.
1) The Trigger Angle Offset was wrong. If so, fix it and move on with live
2) There's something mechanical going on with your engine
....
Also: please post your timing table!
Thanks for the help. I've been busy with reliability testing and have not gotten back to this yet. But, I had swapped back to the stock ECU and adjusted timing using normal procedure and was running fine. I don't think there is a mechanical problem.

Here is my timing table.
tomiata-timing.jpg
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I was running TS Trigger Angle Offset of 0. Russian, what value did you have on the hunchback?
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Re: 1991 Miata #20 Hunchback

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Still did not have a chance to check - working on new brain board and Frankenso assembly with new shop :(
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Re: 1991 Miata #20 Hunchback

Post by stefanst »

tomiata wrote: Thanks for the help. I've been busy with reliability testing and have not gotten back to this yet. But, I had swapped back to the stock ECU and adjusted timing using normal procedure and was running fine. I don't think there is a mechanical problem.

Here is my timing table.
[...]
I was running TS Trigger Angle Offset of 0. Russian, what value did you have on the hunchback?
That timing table looks very conservative. I'm running 10-15 degrees more pretty much everywhere across the board. Now that's with a modified '99 1.8l head on a 94 short-block (lower compression) and 93 octane, but still... I can't see how your table would generate knock even on 89 octane.

So if you verified that timing is offset with a timing light, then just adjust your offset and don't worry about it.

My timing table:
99 timing table.png
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Re: 1991 Miata #20 Hunchback

Post by AndreyB »

One way to convert NA into NB.
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Re: 1991 Miata #20 Hunchback

Post by stefanst »

That'll work! Good luck!
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