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Did you leave all of your exhaust connections loose during assembly to allow for positioning exhaust components BEFORE tightening clamps/hardware? That's the key to getting a good noninterference fit. It doesn't take much movement on one end to make a big difference on the other end. The vband clamp snapped because you over torqued it. Don't put torque on a vband clamp like you would a standard exhaust flange bolt/nut.

@m2cupcar I did leave the clamps loose during assembly, but then I tightened everything down before installing the O2 sensor. During O2 sensor installation, I had to loosen everything again, but after that (even with clamps loose), I couldn't find a non-interference fit. Thoughts?

Quote:

Originally Posted by Dwalk51 (Post 1513367)

Has anyone had issues with downpipe fitment? I'm working with an NA 1994 Miata, MKTurbo kit purchased and delivered around August/Sept/October 2017.

Background: I'm putting the final touches on my install and part of that was recalibrating the O2 sensor and actually threading it into the provided bung in the downpipe. When I went to put it in, I couldn't fit the sensor into the bung in the downpipe without removing that V-band clamp next to O2 sensor bung to give myself enough clearance. Even then, with the sensor tightened in the bung, the top end with the wires was smashed into the transmission tunnel wall. Is that normal? I'll include a crude cross section drawing to illustrate. It may have something to do with the broken V-band clamp detailed below.
https://cimg9.ibsrv.net/gimg/www.mia...9ac40210e1.png
After installing the O2 sensor, I had to loosen all of the exhaust v-band clamps (muffler and turbo side) to create enough 'give' in the system to reattach the exhaust clamp next to the O2 sensor, and once that one was back on, I reattached the clamp at the muffler. I was on to my last clamp. At the time I thought this was the last bolt I needed to tighten before starting up my newly turbo'd car for the first time. And then the v-band clamp next to the turbo snapped in spectacular fashion while I was tightening it down, shearing the threaded rod with the nut still attached. I've attached a pic of the carnage (sorry if it's massive, I tried to resize it). When it snapped, the downpipe jolted downwards, leading me to think that I may have stressed the connection between the turbo and downpipe.

https://cimg2.ibsrv.net/gimg/www.mia...5d7741516a.jpg

Has anyone else had similar issues with the downpipe not quite fitting right?? When I had everything hooked up but not tightened, there are two areas where fit seems to be an issue. The downpipe was forced up against the transmission (couldn't rotate any more) and the O2 sensor was smushed into the transmission tunnel wall. Even if I throw another v-band clamp on at the turbo, I'll still have these tight spots. Am I missing something obvious here? I appreciate any help/advice you guys my have.

Thanks,
Dylan

Shoot me an email.

Quick update, shot Lars an email and he's been helping me.

I originally set everything up loose and then started tightening down when the v-band clamp snapped. To make sure I'm not crazy, I went back and tried it again to see if I could wiggle things around for a better fit. No matter how I adjust things, the downpipe is stuck. The o2 sensor is in the way of where the downpipe needs to go for a non-interference fit. I think the o2 sensor is meant to fit more straight up and down, or angled toward the transmission instead of the tunnel wall. How are y'all's bungs pointed? I snapped this picture to illustrate:
https://cimg5.ibsrv.net/gimg/www.mia...b19930b190.jpg

Quote:

Originally Posted by Dwalk51 (Post 1513870)

Yeah generally they are a bit more pointed up then that. Not sure why I marked the spot for the bung that far over on yours.

Some potentially useful information.

I purchased this V-Band adapter (same one linked a few posts back that didn't fit) along with this turbo. I measured the compressor and exhaust inducer and exducers and it lined up pretty much exactly with what they have quoted on their page:

Billet Compressor Wheel Diameter: 53mm / 75mm
Turbine Wheel Diameter: 57mm / 65mm

Here's how the flapper fits:
https://cimg5.ibsrv.net/gimg/www.mia...2852cf2e5a.jpg

A little close at the top but it looks like it'll work.

Shot of the billet compressor wheel:
https://cimg6.ibsrv.net/gimg/www.mia...dd9e340c29.jpg

Quote:

Originally Posted by cpierr03 (Post 1518076)

Very curious to see how this performs.

Anyone fit the intercooler without cutting the splash guard?

Quote:

Originally Posted by Shaneg217 (Post 1521366)

Anyone fit the intercooler without cutting the splash guard?

Confirmed not possible on any chassis

I used Flyin Miata instructions for cutting the air dam. Cut holes on cold side for piping, on the undertray. Used a piece of corex, screwed to the undertray and into the bottom of the bumper.

Quote:

Originally Posted by Shaneg217 (Post 1521366)

Anyone fit the intercooler without cutting the splash guard?

Splash guard and under tray will need to be trimmed. For the NA there is a hood latch bracket that needs to be pulled off and either thrown in the trash or cut a bit to fit the IC. The IC goes up all the way against the bottom of the hood latch.

I generally leave off the splash guard and undertray during the initial install. This way it makes checking for leaks, and trouble shooting the install a bit easier. After driving for a few weeks and everything working well I recommend going back and cutting up and installing the undertrays.

So first start up went amazing. Runs great and holds stock wastegate pressure (about 7psi) rock steady. Until it gets hot. For some reason the WG won't seal shut well and I can hardly build boost. The WG actuator arm can easily by wiggled to slightly open and close the WG. You can hear the flapper rattle and not shutting completely even at idle. No leaks that I can find. Any ideas? I have a MBC inline but it's open all the way for now to run stock WG pressure. Again, issue only happens when hot after the first few pulls.

How much pre-load do you have on the WG actuator?

Quote:

Originally Posted by navalhawkeye (Post 1525920)

How much pre-load do you have on the WG actuator?

2 turns or so. I added a bit more to tighten up the slack and it successfully added preload. Made 11ish psi then did the same not seal deal when it got hot and wouldn't build much boost.

Does the WG spring have any resistance after the symptoms develop? e.g. disconnect the actuator arm from the flapper and pull on it after this happens. Is resistance different than when it's cold?

I think I had more than 2 turns of preload on mine.

It does still have resistance. Not sure if different cold vs hot. I'll check it out after work. And I'm not exactly sure how much preload I initially had. All I know is it pushed 7psi and held it solid. Which would be perfect if it did that consistanly.

Make sure both housings are securely fastened to the chra. That stuff doesn't always arrive fully torqued from China. Some of the kids building them are smaller than others.

Be careful cranking on the compressor side bolts. It's easy to strip a couple of them because the housing is thin. Also, you may want to use some teflon tape on the couple that actually go through the housing into the scroll area to help seal them. And one last thing would be to get one of the T3 Turbocharger Compressor Housing Gasket because they don't come with one from China...

T3 Turbocharger Compressor Housing Gasket

At least those things helped when I installed my kit a couple years ago from Lars. Also, I used 3 turns preload.

I cranked all the bolts down... including a compressor housing hole. Learned my lesson there. Installed helicoil inserts and upgraded the bolts. Didnt use any sealant of any kind though. That wouldn't have an affect on the wastegate actuator at all if my logic is correct. I tested the tension of the arm cold and warm. Cold seemed more consistent. Hot, not so much, though it was awfully hot haha. Hot arm has the WG resting open when car is hot and just turned off. Could the actuator can have a poorly tempered spring? I'm not sure how they work, honestly.

Double check the actuator alignment