Ugh! I think there is a rant thread somewhere on BITOG about flat-plane cranks.
When will people learn engine config means nothing on output?
- Thread starter DriveHard
- Start date
Here Are The 10 Most Powerful Cars With A Straight-6 Engine
Over the years, there have been some straight-six engines that packed serious amounts of horsepower, and these were the most powerful of them all.
www.hotcars.com
I am a fan of inline engines, the forces on the cylinder walls seems to be less judging by the amount of bore wear and piston wall scuffing vs a V engine. Forces on the crankshaft come into question also.
Analysis of Forces on Reciprocating Engine Components by EPI Inc.
Analysis of Forces on Reciprocating Engine Components - Propulsion System Technology and Components for Aircraft, Automotive, Marine and Industrial Applications
www.epi-eng.com
Engine configuration and balance
'Engine configuration and balance' published in 'Vehicular Engine Design'
link.springer.com
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I can think of some vee engines that don't wear the bores, the Ford 302 was notorious for perfect bores regardless of the mileage, but that's got a pretty short stroke. I assume the 289 was the same.Here Are The 10 Most Powerful Cars With A Straight-6 Engine
Over the years, there have been some straight-six engines that packed serious amounts of horsepower, and these were the most powerful of them all.
I am a fan of inline engines, the forces on the cylinder walls seems to be less judging by the amount of bore wear and piston wall scuffing vs a V engine. Forces on the crankshaft come into question also.
Analysis of Forces on Reciprocating Engine Components by EPI Inc.
Analysis of Forces on Reciprocating Engine Components - Propulsion System Technology and Components for Aircraft, Automotive, Marine and Industrial Applicationswww.epi-eng.com
Engine configuration and balance
'Engine configuration and balance' published in 'Vehicular Engine Design'
I am going back to a time when every mechanic owned a ridge reamer. I remember doing a Ford 351 that has a wicked ridge in it and slightly oval from wear. A similar mile 230 six had wear in the bores but the wear was universal, nothing scientific. The oil was not much better than machine oil in those days.
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$100 Site Donor 2021
Yeah, the 351 had a longer stroke, my memory on this starts with the 302, lol. I saw SBC 350's with oval'd bores that needed a ream but the 302's were always immaculate. I assume it's due to them being very over-square, 4" bore, 3" stroke.
I guess its actually the angles of the rods at mid stroke that is the factor for oval bore wear.
I have a 96 YZ250 with what's called a long rod kit. The motor runs significantly better with a 130mm rod vs a 125mm rod, and has less cylinder and piston wear. This motor has a base gasket so the kit is the longer rod and a 5mm thicker base gasket.
I believe the engine guru's on Yamaha's racing teams figured this out quite quickly, but the production engineers didn't change back to longer rods for a couple years.
So I guess a longer stroke crank results in bigger rod angles unless they increase the rod lengths as well. I guess with most car engine blocks. they don't vary the deck height from the crank centre if they can help it?
To reduce overall friction, some modern engines have the crank center offset slightly from the bore centerlines to minimize that angle during the power stroke. I'm not certain whether that trick is limited to in-line engines.
The Ford 302 also has a relatively short Connecting Rod & Deck Height, In fact the Rod Ratio or Rod to Stroke ratio is pretty close between the Ford 302 & the GM 350.
*302..........5.090" rod length divided by 3.00" stroke equals 1.68 Rod Ratio
*350..........5.700" rod length divided by 3.48" stroke equals 1.64 Rod Ratio
*351W......5.956" rod length divided by 3.50" stroke equals 1.70 Rod Ratio
This ratio expresses a geometric relationship between the rods, crankshaft and pistons. The lower the rod ratio, the greater the side forces exerted by the pistons against the cylinder walls.
While the 351W has a longer stroke.....Because it's Taller Deck, Making room for a Longer Rod, Has a little better Rod Ratio in terms of cylinder wall loading.
I've tore down some high mileage 350 SBC's with really good round bores & very little measurable Taper, They were 90's blocks with fuel injection.....Mostly Gen 2 LT1. Better casting techniques, Better Iron, Fuel Injection, And better oil all contribute lower cylinder wall wear.
The Iron LSx 6.0L is one of the best wearing blocks/bores I've ever seen, Even with close to half a million miles.
GM 7.4L/454 are the worst I've ever seen, In fact I can place my Bore Gauge in a cylinder where it won't fall out.....Using both hands & squeeze the the top of the deck over my Gauge & the Gauge will fall out! I can distort the bore by hand!
?? 5.090/3.000=1.6967..., which rounds to 1.70.
Compare to my old Subaru's corresponding ratio of 136mm/60mm= 2.27
Your right, Rounded to 1.70.
2.27......That has to be one of the highest I've seen. But that might be common with Boxers for all I know?
2.27......That has to be one of the highest I've seen. But that might be common with Boxers for all I know?