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Old 10-03-2011, 01:49 PM   #41
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Originally Posted by spoolin2bars View Post
Just fyi, my car came with an egt gauge and under wot at the track it sits at 1,600 1650* f
For the last four and a half years. You think your egt's are higher than that? How hot do they need to be to burn a valve? Could they be bent? Still don't understand how your car could run so good with any of the proposed scenarios. You don't know anybody with a real compression tester? Snap-on or craftsman at least. Also as someone mentioned, was the engine fully warmed up? My buddy picked the strongest pistons when he built the engine. Unfortunately, that also meant that the alloy expanded more than the other option. So much so that you can hear piston slap when I turn on the car first time in the morning. I always let it warm up a little while before driving, and never boost until it's fully warmed up.
there is lots of info on warming up forged pistons/dealing with piston slap when cold. there is obviously two schools of thought on this, but you can find plenty of info by reading about forged vs cast pistons. needless to say, from what I understand the longer you idle during warm-up the worse the wear ends up. I won't go into it as its off-topic, but google is there for you when you need it.
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Old 10-03-2011, 02:31 PM   #42
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Originally Posted by RedemPhex View Post
there is lots of info on warming up forged pistons/dealing with piston slap when cold. there is obviously two schools of thought on this, but you can find plenty of info by reading about forged vs cast pistons. needless to say, from what I understand the longer you idle during warm-up the worse the wear ends up. I won't go into it as its off-topic, but google is there for you when you need it.
well, i don't sit there for 20 mins. but i appreciate your concern. and i do understand the concepts at play, with getting heat into the piston quicker to reduce the angles involved and possible wear of the cylinder walls and rings, but this engine was built in 2003, drag raced, driven all across the country before i purchased the car in 2007 where i have daily driven and tracked it approx. 50 times since. so i think it's doing okay at 70-80k since build. (speedometer died over a year ago, lol)

my point was, a cold engine can have vastly different compression readings from operating temp. combine that with a shitty comp. tester can show scary readings. although, the fact that 2 different ones read 60 in the #1 cylinder can be alarming. still doesn't explain the engine running great.
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Old 10-03-2011, 02:38 PM   #43
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Just in from the FB chat.
Quote:
Originally Posted by Mike Bond
ya i prob broke his car
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Old 10-03-2011, 02:38 PM   #44
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Originally Posted by spoolin2bars View Post
well, i don't sit there for 20 mins. but i appreciate your concern. and i do understand the concepts at play, with getting heat into the piston quicker to reduce the angles involved and possible wear of the cylinder walls and rings, but this engine was built in 2003, drag raced, driven all across the country before i purchased the car in 2007 where i have daily driven and tracked it approx. 50 times since. so i think it's doing okay at 70-80k since build. (speedometer died over a year ago, lol)

my point was, a cold engine can have vastly different compression readings from operating temp. combine that with a shitty comp. tester can show scary readings. although, the fact that 2 different ones read 60 in the #1 cylinder can be alarming. still doesn't explain the engine running great.
all good, not trying to attack you or anything. "a little while" is vague and is probably a much shorter time frame for you than me.

back on topic!
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Old 10-03-2011, 02:40 PM   #45
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Just in from the FB chat.
not really a surprise, Bond is cursed.
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Old 10-03-2011, 02:58 PM   #46
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Quote:
Originally Posted by spoolin2bars View Post
Just fyi, my car came with an egt gauge and under wot at the track it sits at 1,600 1650* f
For the last four and a half years. You think your egt's are higher than that? How hot do they need to be to burn a valve? Could they be bent? Still don't understand how your car could run so good with any of the proposed scenarios. You don't know anybody with a real compression tester? Snap-on or craftsman at least. Also as someone mentioned, was the engine fully warmed up? My buddy picked the strongest pistons when he built the engine. Unfortunately, that also meant that the alloy expanded more than the other option. So much so that you can hear piston slap when I turn on the car first time in the morning. I always let it warm up a little while before driving, and never boost until it's fully warmed up.
It was driven about 20-miles before testing, very hot. I don't have piston slap and used Supertech pistons specifically for less thermal expansion.

Yeah, I don't get it either.
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Old 10-03-2011, 03:32 PM   #47
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Originally Posted by Savington View Post
Do you need me to rock you to sleep? I told you on the phone today that your compression tester was ****. Cars with 60-60-120-120 compression don't roll tire in 3rd gear on 80*F days.
I can do something else to help you fall asleep bby

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Originally Posted by hustler View Post
Why would it be consistently wrong? I'm thinking 1/8 turn int he tester fitting either way would make some variation in compression.

Also, do you guys think 243whp at 11psi on 8.6:1 compression is low? I sure do. I'm guessing this motor was blown up a long time ago. I'm really worried about getting in there and seeing a ton of detonation and a dead motor. I guess I'm going to plan on not running TT next year, time to buy a kart.

Edit:
The plugs all look exactly the same too.

Quote:
Originally Posted by hustler View Post
It was driven about 20-miles before testing, very hot. I don't have piston slap and used Supertech pistons specifically for less thermal expansion.

Yeah, I don't get it either.
Dude here is sagacious advice from god's gift to turbo miatas (me). Just say **** it and run it. If it makes power then yay. If you're not detonating then the bottom end will be happy and all is good or at least good enough. Either that or shell out $1000 and fix a problem that isn't seriously hurting performance or incurring risk. Real men run it until it's really broke. /questionableadvice
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Old 10-03-2011, 05:08 PM   #48
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Not gonna lie, I'd drive it until I actually noticed a considerable loss in performance, not sure if you have or not.
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Old 10-03-2011, 05:48 PM   #49
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If I really had all this leak, wouldn't there be tons of black smoke from all the fuel circumventing the combustion process, and wouldn't my WBO2 see that unburnt richness? I'm going to go home, pull some spark, and run this car at 12:1 for a few days and see what it does. For some reason I have this vision in my head of furry carbon on everything causing the leak.
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Old 10-03-2011, 07:01 PM   #50
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Yes, there would be evidence, physical or performance. Race, drink, profit.
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Old 10-03-2011, 08:50 PM   #51
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I just Sea Foamed the green car and got 10-20psi more on the compression test, but still under 100psi.
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Old 10-03-2011, 10:13 PM   #52
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You're headed towards epic thread status, next up is welded piston rings or gas stabilizer in the oil.
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Old 10-03-2011, 10:14 PM   #53
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More seafoam!!!!

and then hit the head with a hammer
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Old 10-04-2011, 03:25 PM   #54
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I have a stupid question: What made you test it in the first place?
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Old 10-04-2011, 03:34 PM   #55
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Originally Posted by hustler View Post
If I really had all this leak, wouldn't there be tons of black smoke from all the fuel circumventing the combustion process, and wouldn't my WBO2 see that unburnt richness? .
It would still burn, just in the manifold, turbine and exhaust.
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Old 10-04-2011, 05:15 PM   #56
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I have a stupid question: What made you test it in the first place?
I had weird numbers when testing the daily so I thought I'd "get baseline number off the turbo Miata because I know that motor is good".
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Old 10-04-2011, 05:16 PM   #57
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It would still burn, just in the manifold, turbine and exhaust.
Should I epext the turbine to be eroded and destroyed too, requiring another CHRA exchange?
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Old 10-04-2011, 05:19 PM   #58
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Originally Posted by hustler View Post
I had weird numbers when testing the daily so I thought I'd "get baseline number off the turbo Miata because I know that motor is good".
Wait, so you tested compression in one car, got weird numbers, tested a second car, got more weird numbers, and then concluded that the tester is correct and you happen to have two engines with bad compression?
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Old 10-04-2011, 05:24 PM   #59
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Wait, so you tested compression in one car, got weird numbers, tested a second car, got more weird numbers, and then concluded that the tester is correct and you happen to have two engines with bad compression?
Yes, this is correct. You cannot dispute the howling air on the leak test through the exhaust. I was hoping to get a baseline number where the numbers were close on more than one cylinder, it's clear the engine is blown.

I'm also thinking I had detonation or something although I never heard it on the dyno. That's basically the only excuse for eroded, leaky valves.
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Old 10-04-2011, 05:34 PM   #60
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Either this thing is detonated to death or I have exhaust valves that look like this:
Attached Thumbnails
Very scary compression numbers on my turbo car-valve_lap_5.jpg  
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