hughdogz
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Posts posted by hughdogz
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There are two basic types of wheels:
1) Hub centric (the hub centers the wheel)
2) Lug centric (the lugs center the wheel)
I know for sure that '70-'83 Z's are lug centric. Is it possible your wheels are hub-centric?
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^^ that sounds more like "real-life" loading. That's thinking with your dip-stick Cygnus!! (of course
hehe!)I came up with a refinement to a PMOI inspection fixture design, to better measure the time it takes to return to a standstill.
Mount a laser underneath the tribulum disk at zero degrees (horizontally). With it at a standstill, mark the wall where the laser is pointing at zero degrees. If it stays within a certain range (distance) of the mark as it winds down, stop the time. Of course, the laser measurement would be more accurate the further away from the wall you have the 'trib!
Measure the angle of twist by mounting another laser (vertically) at either the floor or ceiling at ten degrees...Now I'm thinking of making one, to measure the difference between a stock 240mm flywheel versus a SPEC. And the stock clutch versus a Centerforce DF. I have quite a few to experiment with.
I'd need a baseline using a circular disk (Iron, steel or Aluminum) to get good number to start with. It would be great to get another piece (of equal mass) that is a ring-shape. The PMOI can be determined for each by known theory. We can find the PMOI's of the flywheels / clutches by interpolating (or extrapolating) the times of the known one(s).
If it works, we could share the results by shipping or sharing the plans for the simple fixture...just a thought
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Hi Guys, I wasn't kidding when I mentioned a non-destructive way of measuring the polar moment of inertia using a "tribulum". It is like a pendulum, but instead of just a mass on a string, it is three strings.
Imagine you have a circular piece of plywood. Then mount three eyes 120 degrees apart near the outside. Then take three pieces of wire to hang the plate to a ceiling, keeping the wires vertical. Then place the flywheel / clutch exactly in the center. Now you have a tribulum.
Twist the tribulum say ten degrees. The amount of time it would take to return to a standstill would indicate the polar moment of inertia (integral of R^2 dM) For a circular plate / uniform disk, it would be (mass * radius^2)/2.
There may be a better way to do it, and I might be able to come up with the energy equation to actually get a number in kg*mm^2 or pound_mass*in^2 from the angle of twist and time.
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Awesome!!
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It would be great if someone could set up a "tribulum" so that we can actually measure the PMOI for all the flywheels and clutches out there!
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...There must be a mathematical equation that can give you a specific sized piping. Thus giving you maximum flow. I would like to hear some ideas from others on this as I have a few thoughts in my head about how to calculate something like this...
It has been awhile since I took a fluid dynamics course in College (~1996) but this is what I can remember...
All else being equal, the mass flow rate through a pipe is m_dot = rho * V * A (rho = density, V = velocity, A = cross-sectional area). Due to the conservation of mass, it doesn't matter what diameter pipe you have, they will both flow the same CFM (mass in = mass out). But as you mentioned, the dynamic pressure drop will probably be greater for a smaller pipe, depending on the Reynolds number (whether it is turbulent flow or laminar, friction causing the turbulence).
To illustrate this point, say that you have a reducer going from 3" to 2". The mass flow rate will be the same, but since the cross-sectional area decreased, the velocity has to increase. Since the velocity has increased, the dynamic pressure has increased, while static pressure decreased (total pressure being the same = Bernoulli's principle).
When in boost, I'm pretty sure that the flow will be turbulent, to make sure, you can calculate the Reynolds number using V*D/nu (V = velocity, D = pipe diameter, nu = kinematic viscosity). You can check if the flow is in the turbulent region or not, using the moody diagram. On average, transition to turbulence will occur at a Re > ~2300. It will depend on the diameter of pipe, velocity, pipe roughness, etc.
- Moody diagram explained by Wiki: http://en.wikipedia.org/wiki/Moody_chart
- More Moody info: http://www.engineeringtoolbox.com/moody-diagram-d_618.html
- Moody friction factor calculator: http://www.lmnoeng.com/moody.htm
Pressure (head) loss depends on fittings / bends, you can add the "K-factors" for the bends / elbows. This will determine the equivalent length of the head (pressure) loss for fittings and elbows, as Sho-z already mentioned. They go into a detailed example here: http://www.cheresources.com/eqlength.shtml
To calculate the head loss due to friction through a straight section of pipe, you can use the Darcy equation using the friction factor from the Moody diagram:
You can also take calculate (seperatly) the static and dynamic pressure changes as well, using Bernoulli's equation.
Like you said, it is a tradeoff, and will ultimately depend on your HP (flow) goals to choose the proper diameter tubing.
Hope this helped...
Last question, from where are you getting your PSI readings from? Are you measuring from the intake plenum, or from an individual runner. I ask this because it makes sense to me that the closer to the cylinder you are, the more accurate of a reading you are going to get.For recording the boost pressure (MAP) I just take it at the intake manifold plenum. For the boost controller, I think it is best to take it nearest the compressor outlet, if not at the compressor outlet itself.
- Moody diagram explained by Wiki: http://en.wikipedia.org/wiki/Moody_chart
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Or a SPEC Aluminum:
Are you going with 225mm size for less inertia? I stayed with the 240mm size for more friction surface.
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Here's what I've been up to lately. I decided to wrap my exhaust with Thermo-Tech "Cool-it" header wrap. They also sell 2000 degree F high temp paint to seal the deal. I also want to wrap and coat the Borla muffler, once I find some ties long enough. Here I welded the mild steel V-band flange to the stainless steel muffler using mild steel MIG wire. Then I welded SS to SS for the muffler to the tip using mild steel mig wire:
(please excuse the mess, I'm still single )The copper looking wrap is their new "TCT Technology" stuff that has copper particles in it...it is supposed to be ~30% more efficient than their normal stuff. However, it is 50% more expensive! So I went with their old stuff to finish the job.
Exhaust in a box!
I got bored, so I thought I'd pretty up the thermostat housings, coolant inlet / heater fitting, and front cover while I have the engine apart.
I still need to get a -6AN bung to weld into the upper thermostat housing to run the head coolant lines...
(I'm not quite finished with this yet, it is a real PITA to do by hand.)And finally, I ordered a 240mm SPEC aluminum flywheel from Tim at S&T motorsport!!
He is really great to talk to and also gave me some free advice on installing the KAAZ LSD way back when: -
Got the Turbo head back from the Machine Shop!!
Actually, it was a long time ago. I've been fighting a flu all weekend, so I thought I'd update since I'm not able to do much else
Pics (of course)
Did my own valve unshrouding, ported and radius'ed the runners, widened the bowls, and removed guide "lumps". Then I drilled and tapped above #5&6 for better coolant removal. All done at home achieving ~1cc tolerance between combustion chambers!!
BRAAP installed new seats with 4/5 angle valve job, installed shortened valve guides, set up the valve train with new lash pads, new seals, etc. He CC'ed the chambers twice to set the valve seat height to achieve a final 1/4 cc tolerance between combustion chambers
(not bad for my first try...thanks again to Paul at Rusch Motorsports
He taught me how to do it!With the head porting, exhaust manifold porting, ultimate internal wastegate, 3" mandrel downpipe, 3" exhaust, T3/T04E turbo, etc. my ZXT should flow pretty well.
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Cool! A hybrid-hybrid turbo.
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Sounds like you're making good progress
Still have some questions of were I should tap inot regarding Cooler lines for turbo as the 300zxt turbo has Coolant lines. Ideas anyone? *I was thinking T off the line going to theHeater core and wrap around back of the engine to the turbo then L back around and back to that line again ..If it were me, I'd try extending the stock coolant lines that route into the throttle body and idle air controller for the turbo coolant lines (the ones that wrap in front of the head).
...Diconnected PS pump for now as its leaking. Question? can you run that rack without pump or should I replace pump soon and just keep filling it. I think bearing going on it from the sounds of things...
I removed the PS pump to make it easier to run my intercooler tubing. You can "loop" the hydraulic lines at the rack. But, it makes the steering kind of heavy. I want to get a manual rack and crossmember someday...
Rust huh? Well, the S130 have flares already built in. You could run S30 ZG flares on the S130. If you need more room, you could roll the inside. I've even seen "pulling" the outside, but it doesn't quite do it for me. You might as well run flares like you've mentioned, but I think it will look goofy unless you have wider wheels to fill the width accordingly. I've seen pics of Z31 flares on a S130 and it looks sweet!also Anyone know of specific wheel flares that work with the 280zxt. Cause I'm getting a tad of wheel well rus so I was going to cut it out and flare them a bit.Hope this helps, -hughdogz
[Edit: You need to follow the forum rules regarding descriptive thread titles. What you are asking doesn't fit into a "Guys and Girls" category. Plus there are only about three girls on this site
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My palm is still on my face! (yeah, I can type with one hand
)About six years ago, I was adjusting my valves so I had to remove the cam cover. I left the bolts in the holes when I removed the cover. Well, one of them fell down the front cover!! I looked down the opening and couldn't see it, and thought it must have fallen all the way down into the oil pan.
I was getting the car ready for a ~2000 mile road trip to MSA and didn't want to pull the oil pan. I thought if I'm lucky, it fell down and it will be okay. Sure enough, I drove it for the next six years like that!!
Well, this year, I dropped the timing chain tensioner spring "down the chute" (Doh!) Then, I tried to recover it through the oil drain hole. BUT the magnet fell off the wand!! Argh!! now I have THREE foreign objects in my engine.
So I pulled the front cover off, and the valve cover bolt, timing chain tensioner spring, and tensioner washer all fell out - they never made it into the oil pan!! I still have to pull the engine / oil pan to get that damn magnet though...
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Exactly!! I got mine from the local Baxters. They were ~$145 and they said they price matched Summit for me.
P/N 202-4206
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Happy Birthday Big-Phil!!
You have 7 months, 20 days on me. '72 was a leap year, but we both missed February 29th...
It is still your birthday over here on the left coast
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I remember when that came out! Wasn't R2D2 a trash can or something? I'll have to check it out.
Thanks! -hughdogz
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Hi TBS, any update on this endeavor?
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I have a KAAZ LSD for a 240SX swapped into my ZXT R200. It wasn't too hard to do. Search for my writeup KAAZ LSD in a ZXT or something like that.]
Later, -hughdogz
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Okay, I'm going out on a limb here, since I could get thwaked for not knowing exactly what I'm talking about, but here goes...
See the red anodized spacer between the ball joint and the bottom of the strut tube?
When you lowered your car by 1-1.5" you changed the roll center. The control arm is now angled closer to horizontal than stock, since the spring is shorter. I believe that where the angles of the control arms intersect is the roll center, which is now lower. What the RCA's do is bring the roll center back up, closer to the stock position.
They are sometimes referred to as "bump steer spacers" that will negate the tendency for the wheel to turn weird if you encounter a bump. I bet if you searched, John Coffey or jmortensen would go into intricate detail about it...
Hope this helps, and I'm not too far off base.
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That makes complete sense John. Since pressure = Force / Area, a larger opening (area) would need a larger force from the actuator to hold the puck shut at the same pressure.
Thank you for the correction.
[Edit: another good tidbit of info I got from John was sizing the proper wastegate actuator. If the wastegate is sized for say 7psi (stock) it can work well at twice that operating boost pressure (~14 psi). More than that and you may be asking too much of it...I want to get an adj one soon where you can swap out the springs]
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Haha!! You guys are cracking me up!
All these polishing threads tonight...
Yeah, you just wetsand it and then polish it. Or you can use a wire wheel as mentioned in the other thread. It was a PITA with the turbo valve cover, since it is wrinkle painted from the factory. I actually used a paint scraper to get it off, but that was years ago. It would be far easier to have it bead blasted first.
I remember reading in a thread that when wheel manufacturers polish their Aluminum rims, they have to get the metal really hot by the friction of the buffing wheel. That requires a lot of HP.
I would be great to have a giant floor standing buffing wheel. Or you could spend hours and hours polishing by hand like I did.
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^^ I agree
1) The safety pop valve probably can't evacuate that much flow to keep the boost low enough
2) If you're using the factory EFI, then that is metered air escaping so you'll be running way rich in boost
Is the turbine housing just missing the internal wastegate housing, or does it have a 3" V-band flange?
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Hi Boardkid,
I measured the wastegate opening in my (early) Ford-style 5-bolt turbine housing and it is a smidgen over 13/16" diameter. The ATP puck I have is a smidgen under 1 5/16" diameter. So, the overlap is about 1/4" around.
I also cleaned up the area where the formed reducer piece meets the flanges:
Thanks to BRAAP for suggesting this!
I don't know if I have boost creep yet or not...my car is still on jackstands.
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I remember that Courtesy Nissan used to sell these but they are NLA...
Thanks, -hughdogz
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You didn't add oil to the strut cartridge tube to enhance the heat transfer?
{Edit: Good writeup Man!! Also, some roll center adjusters might help too. I like the TTT ones myself...}
hehe!)
Measure the angle of twist by mounting another laser (vertically) at either the floor or ceiling at ten degrees...
(please excuse the mess, I'm still single 
)
(I'm not quite finished with this yet, it is a real PITA to do by hand.)
He is really great to talk to and also gave me some free advice on installing the KAAZ LSD way back when:
He taught me how to do it!
Rev happy Flywheel / clutch choices for street use.
in Nissan L6 Forum
Posted
I'm not sure if my verbal description was enough, so I tried making a model first. Since we usually have 8 foot ceilings, I think 7 ft would be a good number. I'm also trying a Dynamic Simulation to see if I can actually get some decent results / numbers to see if it will work.
I know, those hanging "eyes" are overkill, but I had them handy.
I was thinking in order to calibrate it, or to calculate a know PMOI, I could simply get a five-gallon bucket and fill it with sand. Knowing the dimensions and mass, I can calculate the PMOI. Then I can record the time it takes to come to a standstill. Then record the time 1/4 full of sand, and probably be able to interpolate the PMOI for the flywheels / clutches.
I think Tony D might be referring to the springs shown here in a typical clutch friction disk:
{Edit_2: Now that I think about it, if we made the base big enough, we could measure the PMOI of rims too!
}