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MichaelDelaney 
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Late Apexing, YT Feb/23/02 User ID: 416
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Last Here
8/21/2009 |
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so I'm cruising around the web and run into this interesting website article:
click
(actually the other r/s article (click) in there is pretty damn good also ! LOL)
and if you go to the end of the 1st link's 2nd page, there's an excel spreadsheet that calculates the piston sideload and crankshaft load as the piston travels from TDC to BDC.
the amount of load is expressed in terms of the %age of the force the piston top "sees" from combustion (i.e. the amount of "smackdown" on top of the piston when the air fuel mix is ignited and the mix expands = 1.00 and the force onto the cylinder wall and rod/crank bearings are expressed in terms of a % of this) .
it presumes that the force is constant througout the power stroke from TDC to BDC (which may not necessarily be true but what the hay...why not try it and see if we can glean any insights from the graph, right?).
there's a tab to enter the data to get your load graphs in the colored boxes (don't enter anywhere else or you'll screw it up). you enter the rod length and stroke in mm.
so I enter the LS (lowest r/s) , GSR/ITR (low 1.58 r/s) , RSX (better 1.62 r/s), and Civic Si (near ideal 1.74 r/s)....any insights?
here's the b18b, b18c, b16a loading graphs:
here's the b18c, k20c, b16a loading graphs:
the solid lines are crank/rod bearing load, dotted lines are piston sideload.
the first thing you notice is that the load on the crank (solid lines) bearing is not that much different between engines (virtually identical) and the max. load happens at about 70-75 crankshaft degrees AFTER TDC for all of them and it's 10% more than the force that the piston top "sees" from combustion.
the second thing you notice is that the b16a just smokes everyone else for having less wall sideload from the piston on the compression stroke and that the difference between the k20c vs b18c and the b18b vs. b18c isn't that much different for sideloading.
now my question is this: does this relationship change as a function of rpm? I would think so. The higher the rpm the more the load and load difference? what do you guys & gals think?
anyway it was an interesting exercise and some insights to visually show you the loading from r/s.
PS here are the searches for rod ratio and piston speed as phrases for old threads on this topic.
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Who is Michael Delaney?
Type R Teg Baby |
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GSR_J
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JDM Blows in, BC Jan/28/04 1995 GSR User ID: 39408
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Last Here
12/24/2007 |
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So that 4-5 % sideload difference has quite the impact on performance? What about actual piston speed? I've heard the B18C5 piston speed at redline is actually faster than the BAR Honda F1 engine at its redline?
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New life in place of old life, unscarred by trials. A new level of Confidence and Power |
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MichaelDelaney
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Late Apexing, YT Feb/23/02 User ID: 416
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Last Here
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no...I don't think so...the f1 engines of today have r/s's in the 2.2-2.3 range and they rev to 19,000-19,500 rpm fuel cuts.
they'd kill the b18c5 in piston speed.
maybe you were thinking of the old 1980's honda f1 turbos??
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TheGSRGuy |
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V8 power in, IL Apr/01/02 User ID: 1090 Name: Dan
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9/9/2010 |
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Tuan, I'm very handy with Excel. I'd be willing to make you any sort of spreadsheets you want.
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Now: 2005 Audi S4
Before: 1999 GS-R coupe |
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GSR_J
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JDM Blows in, BC Jan/28/04 1995 GSR User ID: 39408
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12/24/2007 |
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You're probably right about the old 1980's F1 turbos.
That's some really good information. This goes to show how much engineering and datalogging goes into today's hi performance automobiles. On the other hand, you look at some of the lower end cars and wonder why they "didn't do this" or "why'd they do that?" I guess they have their reasons. I still think Honda is at the forefront of engine technology in the consumer market. It just seems that everyone else is content to follow. Variable valve timing is a perfect example of this.
Just imagine if Honda raised the hoodline on our cars...
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MichaelDelaney
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Late Apexing, YT Feb/23/02 User ID: 416
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Last Here
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regarding your 5% question: yes.
dan: thanks but I can do a mean excel spreadsheet too...LOL
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hpracing007
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TX Dec/22/02 2000 LS User ID: 13881
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9/7/2010 |
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okay... i was looking at that proof of how he got the formula and such but got a question about sideloading in general
I've heard/seen though reading r/s ratio articles that the sidewalling can be so bad that it can cause the cylinder walls to deform, actuallying making the combustion chamber not a true cylinder any more due to shape/tolerances.
Is sideloading random or is there a particular reason why it occurs on one side and not the other? Lookin at the chart it can be reduced by changing the rod length but are there any other factors which cause it to wear the walls in a certain way?
edit: I might be missing the point or something completely obvious haha, which i might be, cause me and physics don't get along to well
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One question from my Mercedes-Benz Test:
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One of the answer choices:
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Changes To This Post: » Added Additional Post Text by hpracing007 at 10/27/2004 10:31:03 AM |
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JustinKlemgold |
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PA Mar/03/02 2002 Type-S User ID: 673
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Quote: Originally posted by GSR_J on Oct/27/04
So that 4-5 % sideload difference has quite the impact on performance? What about actual piston speed? I've heard the B18C5 piston speed at redline is actually faster than the BAR Honda F1 engine at its redline?
They have that written in the Type-R brochure...I don't know if that's when the Type-R came out or what. Josh has it in his article too. That was 8 years ago, though, remember.
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02 RSX Type-S. Love it.
HT and TI....pretty much the same now. Sad.  |
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MrNiceGuy
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Aug/28/02 1997 GSR User ID: 7179
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Quote: Originally posted by MichaelDelaney on Oct/27/04
no...I don't think so...the f1 engines of today have r/s's in the 2.2-2.3 range and they rev to 19,000-19,500 rpm fuel cuts.
they'd kill the b18c5 in piston speed.
maybe you were thinking of the old 1980's honda f1 turbos??
BMW's P83 (F1 engine) maximum piston speed is almost 40 m/s.
Average piston speed is about 25m/s.
Max piston acceleration is 10,000g; that's 98,100 m/s^2 or about 30,000 feet/s^2
ITR's average piston speed at 8500rpm is 25.22 m/s
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Go hard or go home!
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Changes To This Post: » Added Additional Post Text by MrNiceGuy at 10/27/2004 12:30:11 PM » Added Additional Post Text by MrNiceGuy at 10/27/2004 12:21:08 PM |
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DaBoyNBlu
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AL Apr/28/02 User ID: 1411
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i don't think rpm would affect the proportion, since the proportion is defined by invariables in the setup.
rpm just makes that 5% generate a lot more force.
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I'm deactivating my account. TI is becoming another HT. |
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codenamezero  |
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Canada, ON Jan/15/03 1999 SE User ID: 15302 Name: Eric
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9/9/2010 |
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hey MD, i have a question, would getting the better R/S ratio allow us to rev higher?
having better R/S ratio gives less sidewall load, so when you rev higher, less danger of throwing a rod... and this is also why b18 have a lower redline than gsr/itr as well...
ideally, if we can have NO sidewall load (this is impossible hehe...) then no matter how fast/high you rev, the piston would go up and down safly and easily... thus can rev higher...
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DaBoyNBlu
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AL Apr/28/02 User ID: 1411
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isn't that the whole basis for a better r/s ratio? to rev higher safely? i do believe so.
also, the b18b doesn't rev higher b/c it doesn't need to, with the cams it has, and the corresponding valvetrain. not b/c of the r/s ratio.
and, there is still a limit on the redline, regardless of the sideloading, b/c there's more factors to throwing rods than sideloading. there's rod/rod bolt stretch, piston speeds, wristpin strength, ring flutter, oiling, etc etc.
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BlueTeg |
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Margaritaville, AZ Feb/21/02 1999 LS User ID: 215 Name: Gabe
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Quote: Originally posted by codenamezero on Oct/27/04
hey MD, i have a question, would getting the better R/S ratio allow us to rev higher?
having better R/S ratio gives less sidewall load, so when you rev higher, less danger of throwing a rod... and this is also why b18b have a lower redline than gsr/itr as well...
Uhhh....he's been preaching that for the past 3-4 years (at least). Where have you been? 
Articles?.....Swapping Parts For Power?.....Bueller?
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