HI all - was finally able to get out on the track again and while I have done the best I can to heat shield/wrap protect everything I can, the boost signal line that runs to my wastegate is melting. I believe the metal nipple on the wastegate itself is melting the hose from the inside out. I had previously used silicone hoses that were supposedly good to 500F and then found rubber lines supposedly good to 600F but both have failed. I'm in the process of using a 1/16" npt to -3AN to 3AN ss line to a rubber hose adapter to then rejoin to the nipple on the EFR boost controller I have. The SS line will run long enough to hopefully dissipate enough heat so that by the time the rubber line rejoins up, it wont be hot enough to melt the rubber line I will still need. The EFR boost controller doesn't have ports on it that allow me to change to an AN fitting and run SS the whole way. I may end up having to swap it out for a mac valve, but had bad luck with consistent boost control with it so thats why I have the EFR.

Anyhow, I was posting to see what others have done to stop wastegate lines from melting. Maybe someone has something creative I haven't thought about yet and/or this can just be a good future google search result for someone else that will one day have the same problem.

 

I'm not an EFR guy, but I've never had a wg line melt. Plenty of track abuse and I use regular *** vacuum lines. Just curious if this is under track abuse, or street use. And maybe timing is too retarded resulting in high egts?

 

Track abuse. The first time it happened I was on a stock motor with a remote tune the guy said was conservative. This time on a fully built motor that was also tuned 'conservatively.' I didn't consider the high EGTs being at the source of the issue. It might matter that I also have an external wastegate. Where as on the internally wastegated stuff, it seems the length of the rod connecting the spring gets the entire system far away from exhaust temps, the external wastegates are directly in the party. Second picture is not exactly how mine is, but not far off.

 

Ahh, ok that makes more sense to me, I was picturing the IWG EFR setup like the first pic. The EWG hanging over the manifold definitely looks like it could/would melt under track abuse.

Sorry, I don't have much more to add, but interested to see what others think.

 

Is your EWG water cooled and hooked up?

 

No, turbosmart comp40.

 

If your theory of the line melting from conductive heat via the nipple, an AN line won’t help, they’re still nylon/rubber/PTFE or whatever flavor internally, just wrapped in braided stainless.

If that actually is the heat source causing the issue I’d think you’d need to go to some sort of copper or stainless hardline/tubing for a stretch off the wastegate before then transitioning to a flexible line where it’s cooler.

Pics of your actual setup would help, as well as maybe a pic of a failed hose. Should be pretty easy to tell if they are melting from the inside out at one end or from the outside in from radiant heat.

 

Maybe attach this "conservative" tune as well, it could maybe be creating some excess EGTs.

If I was looking to put a high temp 1/4" vacuum line somewhere, I'd be looking at the -4 push-loc hose, it's good for ~250-300F

 

So I guess I should clarify. I used the word 'melted', I should have said this: Fuel line rated to 500F was heat cycled until the tip was so brittle it cracked into a million pieces. Then I tried a 500F silicone line that some how caught on fire. Previously I had used a silicone line semi-successfully, but it also heat cycled itself until it was so brittle it cracked in a million pieces.

Here's a pic


Best picture I had on my phone, arrow points to the metal port on the external wastegate where it connects to the rubber/silicone hoses I've tried. I used DEI heat shielding and as best I could tell, that protects the rest of the line.





Here's my ignition table. I previous posted this and was told by a few members that the 175kpa and above was too aggressive so I backed it off 3 degrees. On track though, I use wastegate pressure and so I dont go above 150kpa. I will also say, the 'melting' also happened on a previous tune I had done by a different tuner for a different motor.


Here's a pic of the waste gate side of the silicone line I used. I'm not sure it'll be helpful, but it caught on fire. The previous silicone hose and fuel line hose I used did not do that. Instead they simply just looked like the line had aged 50 years and were brittle enough that even light finger pressure and it just fell apart in to little pieces of hardened silicone/rubber.

 

Hmm, interesting failures. I guess my first thought would be to just clock the fitting such that the WG hose runs straight back towards the firewall or goes out over the valve cover, and just use a longer run of hose versus going directly over the turbine housing.

 

Yea, I feel like I tried this but the lower portion of the WG wasn't easily 'clockable' but I'll break it open and look. My AN fitting comes in tonight, so I while I have it broken down for that I'll try to do the same. I dont think the AN can be worse that what I have now even if it isn't the final solution.

 

Instead of running the hole right over the top of the manifold, relocate it to run over the valve cover like in blue below.

Go to a junk yard and take some valve cover bolts off a Ford Ecoboost 4cyl. They are the same length and pitch as a Miata VC bolt and they also have a M6 stud on top of them. That stud is great for mounting p-clamps to. I use them on my motor to pull the oil supply hose away from the manifold heat.

 

Great suggestion! I actually did do this for the track day. The problem is the melting part is actually the portion which touches the wastegate's port for boost reference. For anyone else, I called Turbosmart to see what they recommend since they make my ext. wastegate and they said a stainless line with AN fittings which is what I had already ordered. I have a 24" which I'll run all the way until the port on the boost controller and then use an adapter to go to a short rubber hose since the boost controller only has a plastic nipple to push a rubber hose over.

 

I re-read your dyno thread, and I can't help but think something is still off here. You've got high EGTs and low power from that EFR, where most folks crack 200whp at 7-8 psi on that turbo you were making 160.

You are sure your base timing is synced properly, and unlocked/set to use the map? Beyond the timing map, have you checked logs to make sure something else isn't pulling timing, and that the ECU is actually commanding the timing values you expect? I could be way off, and I mean no offense, but this does make me wonder what your EGTs are and if something is off. Your mechanical timing looked spot on to me, in that pic you showed in the other thread, so that seems to not be the culprit.

 

This is why I love coming back to Miata turbo, you guys are awesome! As for some answers, after I took those pics I installed a 36-2 timing wheel and redid base timing so I'm positive that is right at least. Someone in that thread mentioned high flow restriction from the cat and so I removed that and at least my butt Dyno said it's great. I will admit, I have almost no real world knowledge of tuning and do basically just handed the tune over to a local guy that came massively recommended and supposed lly has been racing na and blown miatas since the beginning.

I have a ton of logs from the race weekend so I'll go back through and compare the timing table values versus what is being logged. Would it be worth it to get an EGT sensor and pipe it into ms3?

 

Here's what I did tonight with a ss brake line (3AN), a 1/16NPT to 3AN and a barbed hose adapter





Can't truly test until I'm on the track again, but I'll give it some what fore and give you guys some infrared readings. Also notice my external wastegate who's paint was original black but has since been heat petina'd to a light brown/bronze.

 

Here are some pictures of different temps around the system after a barely spirited street test drive:

 

I wish I was more help, but I think EGT's could be a good idea and would give you an idea if anything is wrong (restrictions, timing, wacky AFR sensor, etc.) will all manifest there. I can't say if your infrared readings are bad or good, I have no idea, once I get my car back on the road I can take some of my setup to see how it compared. Though I'm on e85, so probably a big difference just from that (and maybe something you should consider).

Even a good tuner could miss a small or non-obvious issue causing timing retard based off a whacky sensor or something. For instance long after switching to e85 we learned that my car was pulling a lot of timing/fuel on longer high boost pulls due to false low eth % readings - which was because I had the eth % sensor on the fuel return line and at WOT high power not enough fuel was flowing through it so readings were inaccurate (showed a massive drop in eth%). A very renown tuner in my area that tuned the car initially didn't catch it, and my buddy/tuner did catch it when we were street tuning (he's the MVP). I never would have noticed it to be honest, but now I look way closer for that kinda thing.

So maybe throw up some logs for the gurus to scope out. And again, maybe this isn't a sign of worse things on your tune. The dyno could read low, or you could have fixed that with the cat delete stuff, and the wastegate line melting (though I've never heard of this) could be something to do with low boost on your EFR turbo having to push a ton of exhaust through the WG. I know you weren't running very high boost levels. This is all speculative on my behalf, I just know I've been around turbo miatas, and this forum, for a long time and honestly have never seen this issue.

 

I cooked two chinese turbos with IAT retard and never failed a rubber WG hose. That said, mine were sleeved with reflective aluminum air conditioning tape from Harbor Freight. My oil feed line had a spark plug wire heat sleeve over it.

Don't use IAT retard except for very high temps if you can help it.

 

Attached is my tune and a log file from last night where I did a couple of quick pulls at wastegate boost. Not sure if that is enough to help.