DIY Homemade Plenum Plate
#81
01-14-2012, 10:41 PM
Every time I read a plenum thread I am tempted to determine where the TTY came from. Obviously, the parts dept at the dealer has no idea. The parts manaul only lists a part number and description is "screw and washer." I recently e-mailed Dodge engineering, and they only referred me to the dealer.
I have used TTY bolts in a number of situations and conditions. The head bolts on my Jag are TTY (and expensive). I have utilized TTY bolts on hight voltage electrical installations (power plant installations).
Every TTY bolt I have ever seen has NOT been threaded the entire bolt length, as this would adversely effect torsion of bolt. Additionally, the shank of the TTY bolts are typically turned undersized for a length of the unthreaded part of the bolt, and TTY bolts are typically hardened.
So I am not saying that the intake bolts are NOT TTY, but they do not appear to be TTY to me, based on my experience (yes, engineering background). This beeing said, I did install new bolts when I replaced my plenum. As these bolts appear to be prone to breaking off, I decided to replace and use never sieze on them.
So do not flame me.......if they are truly TTY, I would like to know where the informcation comes from. I was unable to have this confirmed.
I have used TTY bolts in a number of situations and conditions. The head bolts on my Jag are TTY (and expensive). I have utilized TTY bolts on hight voltage electrical installations (power plant installations).
Every TTY bolt I have ever seen has NOT been threaded the entire bolt length, as this would adversely effect torsion of bolt. Additionally, the shank of the TTY bolts are typically turned undersized for a length of the unthreaded part of the bolt, and TTY bolts are typically hardened.
So I am not saying that the intake bolts are NOT TTY, but they do not appear to be TTY to me, based on my experience (yes, engineering background). This beeing said, I did install new bolts when I replaced my plenum. As these bolts appear to be prone to breaking off, I decided to replace and use never sieze on them.
So do not flame me.......if they are truly TTY, I would like to know where the informcation comes from. I was unable to have this confirmed.
#82
01-15-2012, 12:11 AM
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#83
01-15-2012, 12:32 AM
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very good point augiedoggy. I agree based on what I've read too that the bolts are in fact the problem. That's a classic example of an engineer thinking he can function as a mechanical designer. A classic pitfall and I know very few exceptions to this rule!!! 15 years doing mechanical design has clearly shown me this.
I've pulled the thermal expansion properties of the following.
Just a quick internet search yielded that 400 series stainless is typically used for automotive exhausts although I'm relying solely on the internet search which may or may not be accurate.
The CTE range for sand cast aluminum is defined from 200-800 series sand cast aluminum which i'm assuming will cover the mopar half kegger.
400 series stainless would refer to mopar steel stamped plenum although I'd be surprised if they used something expensive like stainless steel versus mild steel. Since it's magnetic my guess i mild steel and I'll go with HSLA (high strength low alloy) since it is typical of stamped steel parts in automotive.
Grade: 200-800 series sand cast aluminum (kegger),
CTE: 24.7-25.5 µm/m-°C
source: matweb.com
Grade: 6061 (pplate)
CTE: 25.2 µm/m-°C
Source: matweb.com
Grade: 7075 (pplate)
CTE: 25.2 µm/m-°C
Source: matweb.com
Grade: 400 series stainless
CTE: 9.2-18.2 µm/m-°C
Source:matweb.com
Grade: HSLA Steel (probably the stock plate material)
CTE: 12.4 µm/m-°C
Source: aksteel.com
with this info my professional opinion is that the closer the expansion rate, the better, ESPECIALLY if you have orings or gaskets between parts. So in this case, going to an aluminum plate definitely achieves consistent expansion rates on both plate and intake. That is great but it doesn't matter which material you use if the bolts bottom out due to a shallow blind hole/bolts that are too long then you are gonna lose.In defense of Mopar, it's pretty easy to overlook a shallow hole in design but I'm not going to go as far as to say that is acceptable when we pay so much for a vehicle. I'm sure this is more than you guys want to hear on the topic (see my other posts regarding competency).
This is not new news to a lot of folks on here but it was fun to research considering the fever/cold chills/aches that came down on me today!
Just a quick internet search yielded that 400 series stainless is typically used for automotive exhausts although I'm relying solely on the internet search which may or may not be accurate.
The CTE range for sand cast aluminum is defined from 200-800 series sand cast aluminum which i'm assuming will cover the mopar half kegger.
400 series stainless would refer to mopar steel stamped plenum although I'd be surprised if they used something expensive like stainless steel versus mild steel. Since it's magnetic my guess i mild steel and I'll go with HSLA (high strength low alloy) since it is typical of stamped steel parts in automotive.
Grade: 200-800 series sand cast aluminum (kegger),
CTE: 24.7-25.5 µm/m-°C
source: matweb.com
Grade: 6061 (pplate)
CTE: 25.2 µm/m-°C
Source: matweb.com
Grade: 7075 (pplate)
CTE: 25.2 µm/m-°C
Source: matweb.com
Grade: 400 series stainless
CTE: 9.2-18.2 µm/m-°C
Source:matweb.com
Grade: HSLA Steel (probably the stock plate material)
CTE: 12.4 µm/m-°C
Source: aksteel.com
with this info my professional opinion is that the closer the expansion rate, the better, ESPECIALLY if you have orings or gaskets between parts. So in this case, going to an aluminum plate definitely achieves consistent expansion rates on both plate and intake. That is great but it doesn't matter which material you use if the bolts bottom out due to a shallow blind hole/bolts that are too long then you are gonna lose.In defense of Mopar, it's pretty easy to overlook a shallow hole in design but I'm not going to go as far as to say that is acceptable when we pay so much for a vehicle. I'm sure this is more than you guys want to hear on the topic (see my other posts regarding competency).
This is not new news to a lot of folks on here but it was fun to research considering the fever/cold chills/aches that came down on me today!
These numbers are not speaking anything to the perception or claim that coefficient of thermal expansion is the culprit. What's missing, severely I must add, is that this is a joint. There several input required to assess a joint's performance. To name a few: material, flange thickness, bolt thread engagement, number of threads, environment loads (pressure, thermal, cyclic?), etc.
Does anyone really think they can gauge the performance by looking at CTEs alone?
Btw, it doesn't make cost effective sense to have the plate as HSLA steel.
Every TTY bolt I have ever seen has NOT been threaded the entire bolt length, as this would adversely effect torsion of bolt. Additionally, the shank of the TTY bolts are typically turned undersized for a length of the unthreaded part of the bolt, and TTY bolts are typically hardened.
#84
01-15-2012, 07:12 AM
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Obviously other factors come into play when you are looking at the life of a gasket. we weren't looking at properties relative to anything else except expansion rates. Sure other factors and properties need to be researched in a design such as this. My gripe is not with ME's or design engineer's. It's with the process in which one becomes an ME or design engineer and whether they are really qualified to do what they do!
Last edited by woodtrucker; 01-15-2012 at 12:31 PM.
#85
01-15-2012, 12:56 PM
AD -- Can you link to the TSB please? I'm interested to know what year it came out.
What exactly are you claiming is a pitfall? Seems like you are placing blame or responsibility on a ME due to bolt length (b/c you are agreeing with AD). However, in typical design cycle environments its the Design Engineer that specifies the bolts, lengths, material, and type (i.e,. specification) for a particular joint design. The ME merely qualifies it and if it does not meet requirements, then it fails.
These numbers are not speaking anything to the perception or claim that coefficient of thermal expansion is the culprit. What's missing, severely I must add, is that this is a joint. There several input required to assess a joint's performance. To name a few: material, flange thickness, bolt thread engagement, number of threads, environment loads (pressure, thermal, cyclic?), etc.
Does anyone really think they can gauge the performance by looking at CTEs alone?
Btw, it doesn't make cost effective sense to have the plate as HSLA steel.
You are absolutely correct that TTY bolts are not fully threaded. THey have a substantial length to the shank. Why? So it can be put into plastic tension.
What exactly are you claiming is a pitfall? Seems like you are placing blame or responsibility on a ME due to bolt length (b/c you are agreeing with AD). However, in typical design cycle environments its the Design Engineer that specifies the bolts, lengths, material, and type (i.e,. specification) for a particular joint design. The ME merely qualifies it and if it does not meet requirements, then it fails.
These numbers are not speaking anything to the perception or claim that coefficient of thermal expansion is the culprit. What's missing, severely I must add, is that this is a joint. There several input required to assess a joint's performance. To name a few: material, flange thickness, bolt thread engagement, number of threads, environment loads (pressure, thermal, cyclic?), etc.
Does anyone really think they can gauge the performance by looking at CTEs alone?
Btw, it doesn't make cost effective sense to have the plate as HSLA steel.
You are absolutely correct that TTY bolts are not fully threaded. THey have a substantial length to the shank. Why? So it can be put into plastic tension.
What? A mech designer AGREEING with an engineer? Hoot!
I have always been one to question things that are sometimes generally accepted - not to dispute, but to learn and understand. Sometimes it takes me a while to wrap my head around something, but the fully threaded part is what kept bugging me on these bolts. But bottom lione, replacing them is a good practice, and not terribly costly. Another symptom that casues me to suspect that these bolts are not TTY - the dealer price is not idiciative a a speacialty itme like TTy. In fact, it has been the most reasonably priced item I have purchased formt he dealer.
#86
01-17-2012, 02:53 PM
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Well. That was a whole lot harder to draw than I thought it would be but I'm finished.
It's pretty dang close and I don't think a few thou one way or the other related to the gasket will be a big deal considering some people on here actually use hand tools to make plates.Too bad I didn't have a scanner that could swipe the whole thing then I could have traced it in solidworks. None the less, here it is! Next step is to get on mastercam and put a cutter path on this baby!
It's pretty dang close and I don't think a few thou one way or the other related to the gasket will be a big deal considering some people on here actually use hand tools to make plates.Too bad I didn't have a scanner that could swipe the whole thing then I could have traced it in solidworks. None the less, here it is! Next step is to get on mastercam and put a cutter path on this baby!
#87
01-17-2012, 03:40 PM
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#88
01-17-2012, 05:02 PM
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I'm in machinist mode now and trying to remember how to setup the mill. It's a stressful thing when you don't run a Haas mill very much. Good thing the shop guys are here to make sure I don't crash! Just about ready to mount the plate and go to town! Don't worry I'll post some pics with the gasket overlayed onto the finished plate. just don't put it on a cmm and compare gasket to plate. use your eyeballs and everything will be just fine!
#89
01-17-2012, 05:22 PM
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I'm in machinist mode now and trying to remember how to setup the mill. It's a stressful thing when you don't run a Haas mill very much. Good thing the shop guys are here to make sure I don't crash! Just about ready to mount the plate and go to town! Don't worry I'll post some pics with the gasket overlayed onto the finished plate. just don't put it on a cmm and compare gasket to plate. use your eyeballs and everything will be just fine!
Well done ignoring the question. Glad I don't have to consider your plate as a possible avenue for usage.
#90
01-18-2012, 12:52 AM
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yeah you better use the even higher tech, highly engineered, with data to prove it, stock steel plenum plate with the bolts that are too long to compress the gasket properly.
Hey, I'm learning about engines, using my cad skills, and machining skills to avoid buying parts and will do my first ever engine mod on my truck! I'm excited and if you change your mind about the plate I'll sell it to you for my special engineer price (50% markup).
I can't wait to hear what you have to say when I break an the head off an intake bolt!
Hey, I'm learning about engines, using my cad skills, and machining skills to avoid buying parts and will do my first ever engine mod on my truck! I'm excited and if you change your mind about the plate I'll sell it to you for my special engineer price (50% markup).
I can't wait to hear what you have to say when I break an the head off an intake bolt!