project ride the cheekbone
#1222
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#1224
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Not sure why, but it took me ******* forever to fix the timing belt. I think the tensioner had come loose and was all sorts of unhappy, so I fixed that and retimed the motor. It was definitely off a bit and the timing belt was loose in a few spots, so this could explain some of the power loss.
I'm going to button things up tomorrow and finally do the leakdown. Is there a good walkthrough for how to go about doing one? I watched the miataking video but he puts mystery oil in for the compression test, which seems a bit odd.
Anything else I should do? Car in neutral or in gear with e-brake up? In gear right?
I'm hoping I can take things out for a test ride tomorrow night.
I'm going to button things up tomorrow and finally do the leakdown. Is there a good walkthrough for how to go about doing one? I watched the miataking video but he puts mystery oil in for the compression test, which seems a bit odd.
Anything else I should do? Car in neutral or in gear with e-brake up? In gear right?
I'm hoping I can take things out for a test ride tomorrow night.
Last edited by ridethecliche; 08-28-2018 at 08:11 AM.
#1226
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Not sure if I can count this a win, but I guess I got lucky...
One of the spark plugs was cracked and wouldn't come out because the ceramic insulation was caught between the chamber and the nut and wouldn't let a socket in. It forced me to look in where I saw shards everywhere. If that ****** had come out without a fight, I feel like I'd be having a very different conversation right now.
So I guess I need to find a pick that'll get it out if the compressor blasts didn't help, which they didn't yesterday. The other shards came out... this one is just stubborn as fahk. Hopefully I'll be able to do the damn leakdown today!
One of the spark plugs was cracked and wouldn't come out because the ceramic insulation was caught between the chamber and the nut and wouldn't let a socket in. It forced me to look in where I saw shards everywhere. If that ****** had come out without a fight, I feel like I'd be having a very different conversation right now.
So I guess I need to find a pick that'll get it out if the compressor blasts didn't help, which they didn't yesterday. The other shards came out... this one is just stubborn as fahk. Hopefully I'll be able to do the damn leakdown today!
#1230
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Friend that I borrowed the compressor from let me borrow the 'air gun'. Managed to shoot out the piece. It was the perfect shape to wedge itself into the spark plug nut and make it inaccessible.
Leakdown test done.
Cylinder 1 and 4 were at about 4-6%.
Cylinder 2 and 3 were at about 12-15%.
I had the valve cover off when doing this, so I couldn't listen through the oil cap, but it seemed like air was coming out through the head so to speak. I couldn't hear anything at the intake or exhaust valves. I redid the middle 2 cylinders twice and got the same results each time.
Cylinder 3 had good compression, so I'm not really sure what's going on. What could cause the middle 2 cylinders to have an issue? I have no symptoms of a HG issue that I can ascertain.
Does this seem to implicate the rings? I can redo the test over the weekend with the valve cover on and listen through the oil cap, but I don't think it's going to change anything.
Leakdown test done.
Cylinder 1 and 4 were at about 4-6%.
Cylinder 2 and 3 were at about 12-15%.
I had the valve cover off when doing this, so I couldn't listen through the oil cap, but it seemed like air was coming out through the head so to speak. I couldn't hear anything at the intake or exhaust valves. I redid the middle 2 cylinders twice and got the same results each time.
Cylinder 3 had good compression, so I'm not really sure what's going on. What could cause the middle 2 cylinders to have an issue? I have no symptoms of a HG issue that I can ascertain.
Does this seem to implicate the rings? I can redo the test over the weekend with the valve cover on and listen through the oil cap, but I don't think it's going to change anything.
#1233
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I mean, lower leakdown on cylinder 2 makes sense because it was low compression. Unsure why 3 is off as well though. I even double checked a few times and trying to turn the crank at all was met with resistance. If it budged at all, it would shoot things over so it was definitely at TDC.
#1235
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I don't know. I would be super impressed if I bent a forged rod at 170 hp. I should have more updates this weekend. Hopefully I'll be able to get a log then as well.
What I was saying was that, well... seeing these numbers posted would have made me think something was up BETWEEN cylinder 2 and 3. Perhaps HG or something, but it doesn't quite make sense here. I'll do another leakdown with the valve cover on and feel for air passing from the tb or the vband past the turbo.
What I was saying was that, well... seeing these numbers posted would have made me think something was up BETWEEN cylinder 2 and 3. Perhaps HG or something, but it doesn't quite make sense here. I'll do another leakdown with the valve cover on and feel for air passing from the tb or the vband past the turbo.
#1238
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Honestly, part of the reason I want to figure this out is so I can call the engine builder and tell him what's going on if it's the bottom end. If it's the head, then that's on me and it's an excuse to do **** to it over the winter.
#1239
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Looks like Spartan was right on the money re:timing being off. I had base timing set up correctly, but that's not really good for all that much if the intake cam is a tooth or two off...
Here's a log with the same tune and just about everything else other than fueling with just the timing belt fixed.
![](https://scontent-iad3-1.xx.fbcdn.net/v/t1.15752-9/40407499_258637104783601_8674323363562258432_n.jpg?_nc_cat=0&oh=1c3644f1e1bb1c30ee3f70143c909a18&oe=5C3BA9AE)
So I'm pretty much where I'd expect to be with this turbo at this boost level, especially because I'm hitting 7 psi at 3300-3500 rpm (when starting from 2k) and then slowly creeping up to 10-11 psi by about 6500. I think getting ebc working will fix that and I'm guessing that better fuel tuning should be good for a bit as well. In any event, car feels like a turbo miata again!
I'm going to redo leakdown and compression now that all this is confirmed. Psyber recommended removing a few things during the leakdown to get a better sense of things.
I can't wait to get this puppy running with EBC!
Should I even bother with the adjustable wastegate? I guess I can try some of the adjustable springs to dial in what I want, but I believe. that things will work far better with EBC with regard to spool and such.
Here's a log with the same tune and just about everything else other than fueling with just the timing belt fixed.
![](https://scontent-iad3-1.xx.fbcdn.net/v/t1.15752-9/40407499_258637104783601_8674323363562258432_n.jpg?_nc_cat=0&oh=1c3644f1e1bb1c30ee3f70143c909a18&oe=5C3BA9AE)
So I'm pretty much where I'd expect to be with this turbo at this boost level, especially because I'm hitting 7 psi at 3300-3500 rpm (when starting from 2k) and then slowly creeping up to 10-11 psi by about 6500. I think getting ebc working will fix that and I'm guessing that better fuel tuning should be good for a bit as well. In any event, car feels like a turbo miata again!
I'm going to redo leakdown and compression now that all this is confirmed. Psyber recommended removing a few things during the leakdown to get a better sense of things.
I can't wait to get this puppy running with EBC!
Should I even bother with the adjustable wastegate? I guess I can try some of the adjustable springs to dial in what I want, but I believe. that things will work far better with EBC with regard to spool and such.
#1240
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There's something odd going on between 5700 and 6300. Stock Miata cams (you have stock cams, right?) make peak torque at 4800 RPM. To make a bump like that at the top you either need a boost spike, a weirdo timing map, or an error in the dyno reading (wheelspin on a virtual dyno, maybe).
--Ian
--Ian