Built Miata Mystery Noise
#21
Has anyone else looked at the tune? 37* at 100kpa at red line, doesn't drop below 30* until 6psi, doesn't drop below 20* until 13psi. Doesn't target richer than 12 until 10psi. Is this E85? Am I crazy?
edit: also constantly running on 5% WUE.
edit2: don't get me wrong, knock readings in the log do say you've got a mechanical issue going on, but yikes.
edit: also constantly running on 5% WUE.
edit2: don't get me wrong, knock readings in the log do say you've got a mechanical issue going on, but yikes.
#23
#24
Nick,
I'm in about the same place-- 9.5:1 Supertechs in bores with 0.0035-0.0040" clearance. 140 miles on the rebuild. It makes a very similar noise, which decreases when warm, but doesn't go away. I wonder if I can get away with just driving it, or if it is eventually going to blow up.
Nic
I'm in about the same place-- 9.5:1 Supertechs in bores with 0.0035-0.0040" clearance. 140 miles on the rebuild. It makes a very similar noise, which decreases when warm, but doesn't go away. I wonder if I can get away with just driving it, or if it is eventually going to blow up.
Nic
#25
Thread update/conclusion:
I swapped the pistons for the second set of Supertech’s I had sitting on the shelf and the noise is finally gone. So I am going to have to assume the verdict is a manufacturing defect in one of the pistons. Be weary ordering ST stuff. This kind of incident plus their documented bad round of valve failures gives me some quality control fright. This cost me 2 months and 2 teardowns.
to be transparent, I am not speaking out against ST, I know lots of people have ran their products for years with no issues, this just happens to be the unfortunate experience I had. **** happens. Thanks everyone for the feedback.
I swapped the pistons for the second set of Supertech’s I had sitting on the shelf and the noise is finally gone. So I am going to have to assume the verdict is a manufacturing defect in one of the pistons. Be weary ordering ST stuff. This kind of incident plus their documented bad round of valve failures gives me some quality control fright. This cost me 2 months and 2 teardowns.
to be transparent, I am not speaking out against ST, I know lots of people have ran their products for years with no issues, this just happens to be the unfortunate experience I had. **** happens. Thanks everyone for the feedback.
#27
This is relevant to my interest. I am in Topeka, KS, Jesse Prather headquarters. I assume you had Siebert Performance do the work? I have my BP4W head at Prathers getting assembled after a refresh, and will be dropping off my engine at Siebert to get machine work done, similar to what you had.
The only main difference between your build and what I am in the process of building is your 9.5 vs my 8.6 ST pistons, also 84mm. Did you find what the "manufacturing defect" actually was? Im curious how/what may have been overlooked by the shop.
The only main difference between your build and what I am in the process of building is your 9.5 vs my 8.6 ST pistons, also 84mm. Did you find what the "manufacturing defect" actually was? Im curious how/what may have been overlooked by the shop.
#28
i had this noise with a 97 head, it was driving me nuts, it felt like i had pinging on free revs but under load, nothing
i had the volve stiffer springs, swapped out to a vvt head with oem springs and the noise went away....now i'm weary of upgrading to supertech dual springs, i don't want the noise to come back :(
i had the volve stiffer springs, swapped out to a vvt head with oem springs and the noise went away....now i'm weary of upgrading to supertech dual springs, i don't want the noise to come back :(
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