The Definitive "VVT swap into 90-97 chassis" Megathread. - Page 2 - Miata Turbo Forum -Boost cars, acquire cats.

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Old 08-19-2014, 01:14 AM   #21
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You are correct, but this is a consolidation thread and I thought it would be good to have it here.
The jumpered fuel pump in my 1990 was instructed by Savington. Dolt ? He seems like he knows what he is doing to me.
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Old 08-19-2014, 02:44 PM   #22
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Quote:
Originally Posted by Savington View Post
Alternator and pulleys
Use a 1994-1997 alternator and pulley. The 1.6 alternator has a different shaft diameter, so a pulley swap is not possible - the entire alternator must be swapped. It may be possible to use the 99-05 ECU with wiring changes and an ECU with alternator control, but few/no PnP ECUs for 1990-1997s will have this feature, so it's easiest to simply use a 94-97 alternator with onboard control.
This is contrary to my experience. We used a new alternator from Autozone, originally bought and installed onto our '90 chassis, with the 1.6 for a number of track days. For the MSM engine swap, we removed the 2-piece 1.6 pulley and small spacer behind it. This spacer was build into the design of the '01 alternator pulley we used. We then found that there's an aluminum lip on the front of the alternator case that the larger 1.6 V-belt pulley doesn't contact. The smaller '01 ribbed pulley, does. 4 screws later we had the front of the case off, and a little grinding took care of the lip. We then bolted up the '01+ pulley, and it lined up with the belts perfectly. After that minor surgery, it was a PNP alternator to the 1.6 wiring (since that wasn't touched), and bolted right on to the MSM motor. It's survived a few hundred street miles and two track days, so I call that successful testing.

Note: when I say '01+ pulley, I'm technically referring to a GarageStar aluminum pulley. However we had an OEM '01 steel pulley on the workbench, and both were dimensionally identical. We also asked Ken at GarageStar for the differences between NA1.8 and NB1.8 pullys, and as far as I remember, they are identical.

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Exhaust manifold and exhaust
Any header from 1994-2005 will bolt up to the head. If you are using a 1994-1997 header, you will need to delete the EGR tube and EGR valve, but you will be able to use a cat and catback exhaust from a 1994-1997 (the exhaust hangar locations are the same for 90-97). Using a 1999-2005 header will allow you to retain the EGR tube, but you will need to have a custom cat pipe built to jump from the 99-05 header flange to your 90-97 catback (you cannot use an NB catback without changing several of the exhaust hangars). If you use a 99-05 header to retain EGR, the 2001+ headers flow much better and are significantly more desirable.
So with a NB OBX header, and '90 RB midpipe, no version (NA1.8 or NB1.8) test pipe will mate the two together?
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Old 08-19-2014, 02:57 PM   #23
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FWIW The Jackson Racing 4-2-1 for NB's has you source an EGR pipe from an NA8. This is how I'm handling EGR on my 96 VVT swap.
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Old 08-19-2014, 03:07 PM   #24
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Quote:
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So with a NB OBX header, and '90 RB midpipe, no version (NA1.8 or NB1.8) test pipe will mate the two together?
That is correct, at least in OEM form. On the NB's the CAT is welded into mid pipe section that goes from the header back to the cat back near the axle. I am assuming that for the 90 RB midpipe you mean the NA [art that would go from the CAT all the way back and include the muffler.
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Old 08-19-2014, 03:08 PM   #25
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Nooooooooooooooooo noooooooooooooo noooooooooooooooo

The exhaust should match the chassis. If you have an NA, use an NA 1.8L exhaust (read: this means 94-97). If you have an NB, use a year appropriate exhaust for your NB. Alternatively, just make your own test pipe to get the flanges to match up.
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Old 08-19-2014, 03:10 PM   #26
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Nooooooooooooooooo noooooooooooooo noooooooooooooooo

The exhaust should match the chassis. If you have an NA, use an NA 1.8L exhaust (read: this means 94-97). If you have an NB, use a year appropriate exhaust for your NB.
Enthuza recommends this too, especially for hanger locations. I talked with him about the best option for a VVT swap car and this is the easiest, bar none.
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Old 08-19-2014, 03:13 PM   #27
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So for a VVT engine in a '90 chassis, I should be using a '94-'97 header, '94-'97 test pipe, and it'll bolt up to the '90 RB cat-back? I was under the impression that the difference between 1.6 and 1.8 exhaust was only the front flange.
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Old 08-19-2014, 03:22 PM   #28
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Curly, stop being a cheap bastard and buy some new crap already.
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Old 08-19-2014, 03:41 PM   #29
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Quote:
Originally Posted by curly View Post
So for a VVT engine in a '90 chassis, I should be using a '94-'97 header, '94-'97 test pipe, and it'll bolt up to the '90 RB cat-back? I was under the impression that the difference between 1.6 and 1.8 exhaust was only the front flange.
Use the '94-'97 header and '94-'97 test pipe. All USA NA cat-back exhaust systems are the same. The difference between 1.6NA and 1.8NA is the exhaust manifold and catalytic converter.
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Old 08-19-2014, 03:50 PM   #30
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Quote:
Originally Posted by curly View Post
So for a VVT engine in a '90 chassis, I should be using a '94-'97 header, '94-'97 test pipe, and it'll bolt up to the '90 RB cat-back? I was under the impression that the difference between 1.6 and 1.8 exhaust was only the front flange.
The different between a 1.6 and 94-97 1.8 exhaust is the front flange on the cat. 1.8 99-2005 exhausts have different hangers and such then the 94-97 1.8 exhausts.
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Old 08-19-2014, 03:52 PM   #31
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Quote:
Originally Posted by curly View Post
So for a VVT engine in a '90 chassis, I should be using a '94-'97 header, '94-'97 test pipe, and it'll bolt up to the '90 RB cat-back? I was under the impression that the difference between 1.6 and 1.8 exhaust was only the front flange.
Yes this our plan, question though, has anyone modified a 1.6 cat to fit in this spot? Or how easy would it be?

Curly is only being cheap on my behalf.
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Old 08-19-2014, 04:06 PM   #32
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Quote:
Originally Posted by my90 View Post
I would like to add to this, mostly minor stuff;
the oil pressure sender, specific to the car needs, to be used
the Air Intake Temp wiring needs to tapped into, on the 1990 I found that the Ground Black/LT GR pin 2P & Signal Red/GR pin 2D in the air box harness for the new sensor
the fuel pump needs to be jumped in the diagnostic box for the early cars at least
the exhaust hanger for the down pipe needs to be retained from the VVT
you will need a wide band if you go standalone
you will need an air intake like AEM or K&N
I found it easier to use the entire VVT exhaust system
You will need a means of holding the hood up in the 1.6L cars as the prop rod will not work anymore
I went with AEM-4 and got good tech support from TSE, thank you Sav !
(Mostly) good info, but much of this is covered in the standalone install, so not specifically pertinent to the install/wiring of the engine into the chassis. Two things to note: You cannot use the full OEM 01-05 exhaust system unless you re-weld a bunch of hangars on the catback, and you can definitely retain the hood prop rod, Rover has a CAI and the OEM hood prop fits just fine.

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This is contrary to my experience. We used a new alternator from Autozone...
I tried to use the 1.6 alternator when I built Rover and the OEM 1.6 alternator uses a smaller shaft than the 1.8 alternator. 100% incompatible. Perhaps the Autozone unit you used is different, but TBQH using an Autozone alternator is not something I would recommend doing.

Quote:
Originally Posted by curly View Post
So for a VVT engine in a '90 chassis, I should be using a '94-'97 header, '94-'97 test pipe, and it'll bolt up to the '90 RB cat-back? I was under the impression that the difference between 1.6 and 1.8 exhaust was only the front flange.
Yes. 90-97 catback is all the same.

Quote:
Originally Posted by oregonmon View Post
Yes this our plan, question though, has anyone modified a 1.6 cat to fit in this spot? Or how easy would it be?
I would source a 1.8 cat if you can, the 1.6 cat is probably smaller and will choke things down even worse. The ideal unit would be an aftermarket high-flow 94-97 cat.
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Old 08-19-2014, 04:14 PM   #33
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I believe modifying the 1.6 cat would only be for tail pipe sniffer emissions every 2 years, so choking wouldn't be a concern.

Damn, so Ryan, I think you need to return that '99 OBX, and buy a '94-'97 OBX.
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Old 08-19-2014, 04:27 PM   #34
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That's what I bought you silly little boy.
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Old 08-19-2014, 04:49 PM   #35
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Cool summary. I think I remember reading somewhere that the 01-05 IAC valve wants to operate at a higher frequency than the earlier IAC valve(s), meaning the stock early ecu won't be able to control it. Is this correct?
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Old 08-19-2014, 04:53 PM   #36
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You guys are busy talking about how to stick metal bits together....

What this keyboard cowboy reallllly needs is the part numbers and links to these connectors:
(this could be somewhere in the unorganized disaster "connector witch hunt" thread)
Edit: Apologies to leafy . Apparently he put together a nice spreadsheet which is organized (but probably still a disaster :P)
TPS
IAC
Cam Sensor
Crank Sensor
VVT solenoid
alternator 2 pin

Last edited by leboeuf; 08-19-2014 at 05:37 PM.
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Old 08-19-2014, 05:09 PM   #37
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Quote:
Originally Posted by leboeuf View Post
You guys are busy talking about how to stick metal bits together....

What this keyboard cowboy reallllly needs is the part numbers and links to these connectors: (this could be somewhere in the unorganized disaster "connector witch hunt" thread)
TPS
IAC
Cam Sensor
Crank Sensor
VVT solenoid
alternator 2 pin
holy **** I posted the mother ******* organized an concise ******* spread sheet from that thread on the first ******* page of this ******* thread, dick.
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Old 08-19-2014, 05:14 PM   #38
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Quote:
Originally Posted by Leafy View Post
This link should probably be in this thread. https://docs.google.com/spreadsheet/...sLU8yX2c#gid=0

Thanks brodeo!!
I need concise, to the point titles
Edit: And props have been giveth
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Old 08-24-2014, 09:56 PM   #39
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The one thing I'll add to this is the EGR valve, for those of us that still need to pass obd2 emissions once a year. The NA8 valve operates differently, has a different connector, but has the same bolt/exhaust openings. Sadly the edge of the valve hits the intake manifold, holding it off enough to not seal. The two choices you have are to either grind the intake manifold and valve edge down a bit, or create a spacer.

Grinding down - Seeing as the valves already have enough inherent issues getting clogged and setting readiness monitors, I opted for grinding the manifold down. I had a spare VTCS mani that was already useless, so I separated the top, drilled through and used a depth gauge at the point right where the EGR valve hits and found there's more than enough material there. I don't like encouraging grinding down manifolds, but it's your pick between that or creating a spacer.

Spacer - For those that would rather opt for a spacer, I went ahead and created a couple to find the right thickness needed. The aluminum I had on hand was in increments of 2mm. I found that 4mm was too small, while 6mm left a visible gap between the valve and manifold. Mazda was kind enough to give us bolts that are plenty long enough to handle all of these. Though, FWIW the NB bolts are a tad bit longer. For my own car I'm grinding the manifold and valve down, but only because I've had my fair share of EGR issues. Hope this helps!
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Old 08-28-2014, 03:00 PM   #40
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What about the tach driver from the 94 coils when using VVT coils? I have been running a VVT engine in my 94 for a couple years with the 94 coils mounted to the firewall. Now I want to wire up VVT coils and I has an extry wire. What do I do with it? I believe it is the one that drives the tach?
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