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Old 08-11-2018, 03:29 PM   #26
rtv900
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Quote:
Originally Posted by tehnation View Post
??? i think you missed something! rexworx does this for a living
You think precision to the ten thousandth is unrealistic? Engineers would tell you otherwise!
right, I do it for a living too.

And I will clarify, precision to a tenth is unrealistic when you are talking about something like this. Can it be done, of course. I do jobs like that too, and they cost double or triple the EXACT same job that only requires 1 or 2 thousanths tolerance.

Frankly, if you are asking for a single tenth tolerance, what temperature are you specifying that measurement at?
Probably no answer to that question right?

If a shop makes your piston in a 60 degree environment and you drive it home and measure it in your garage on an 80 degree day, guess what?
Out of tolerance already.

that's why I said you are over thinking this and that's why it's unrealistic.
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Old 08-11-2018, 04:31 PM   #27
tehnation
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Why would I measure it at home and would I be using the same tools as the shop? I'm an engineer, I understand how precision tools work, humidity and temperature are a huge factor in tool precision, because it's the only real factor that affects consistency. I understand exactly how it works! Not all precision tools are made the same, and there are other factors as well such as the temperature of the tool vs the part. What would cause the discrepancy when doing the measurement in two different environments, is it the the tool or the metal you are measuring? What causes issues mostly is the metal your measuring changes based on temperature. Most tools operate best at about 70 degrees. The measurement should be done at the optimal temperature for the tool, while both objects are at the same temperature. If I measured it at the shop at 70 degrees with the same tool and then at my house at 70 degrees with the same tool, I should get the same results. But I get what you are saying!

Last edited by tehnation; 08-11-2018 at 04:45 PM.
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Old 08-11-2018, 04:40 PM   #28
TDagen
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You guys never seen a 20g break 400whp on E85? Iirc I did 360 on a 18g/E85 back in the day with lower boost, 20 psi I think. Low reading dyno too. For example here's a few 20g's making some power. Btw tehnation I would listen to rexworx sounds like he's got this figured out.

Everyone keep calm and stay in boost.


Link to original thread: https://forums.nasioc.com/forums/sho...hlight=20g+e85



Link to original thread: https://forums.nasioc.com/forums/sho...hlight=20g+e85


Boost chart to go with, showing tapering boost that coincides with the tapering power.

Link to original thread: https://forums.nasioc.com/forums/sho...hlight=20g+e85
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Old 08-13-2018, 12:54 PM   #29
rexworx
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Not trying to argue here. Yes it is correct about the temp changing you measurements. That is why I stated that most people or even shops dont have the equipment or a controlled environment. I personally built myself a area I can keep temp in check.

If parts arrived, they would be placed in the work area for a day for temps to stabilize. The use a digital pyrometer to take temp recordings which I write on the parts next to the measurements.

I also check and zero the calibration on my equipment every day. The equipment would be placed on the bench next to the parts being worked with so temp should be as close as possible.

This same practice would be done by my machinist "in theory". This with help with things being as close to what you want as possible.

As I said this takes a lot of time. Cost a more as well.

Last edited by rexworx; 08-13-2018 at 01:30 PM.
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