mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
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mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
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IaTR6 Dennis Costello Central Iowa (192 posts) Registered: 12/29/2007 02:53PM Main British Car: '73 TR 6 '97 Explorer 5.0 |
Re: Gear ratio calculator, rear gears, and transmission ratios
Jim, I am curious, since Larry Shimp changed from the B cam to Comp's XE264HR. If I recall correctly,
it has 212/218 duration @ .050 and would have .512 lift with 1.6 rockers. Would you plug that in to see? (truth in advertising, or whatever-it's what I have) Thanks, Dennis |
mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
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MGBV8 Carl Floyd Kingsport, TN (4512 posts) Registered: 10/23/2007 11:32PM Main British Car: 1979 MGB Buick 215 |
Re: Gear ratio calculator, rear gears, and transmission ratios
Kelly's cam is ideal for fast street. I have never had so much fun passing cars in places mere mortals wouldn't even consider! :-0
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kstevusa kelly stevenson Southern Middle Tennessee (985 posts) Registered: 10/25/2007 09:37AM Main British Car: 2003 Jaguar XK8 Coupe 4.2L DOHC/ VVT / 6sp. AT |
Re: Gear ratio calculator, rear gears, and transmission ratios
Here's copy from earlier pages of this forum. These pulls were for different timing settings. the most advanced was the great fuel mileage. the other pull was for max power. These points were determined over time from different dyno sessions. The A9L (std Trans.) (A3M ?? A/T) ECM was near top of chart for OBD1 technology. Time dims my memory, but was into Ford Tech at that time. Total package for my car, weight 2440# wet, no driver,T5Z (Ford racing), 3.55 Ford 8.8 Trac Loc,Ford Focus wheels w/205-50R16 tires 24.1" Dia, Similar engine configured to Factory Crate with Hyperutetic pistons, X-303 heads, XE-264-HR Cam, Roller Rockers 1.6 ratio, 65 mm T/B, Pro-M MAF on GT40 Tubular Intake ported Lower by T. Moss, March serpentine pulley system,& Explorer T/C & Crank Damper. Donor car odometer read 118K miles when I got the package to begin my conversion. Carl did initial run at Townsend 2006 after the Terre Haute unveiling in 2005. Usually returned 27-28 MPG at interstate speed with adequate performance. ;-)
Tx 2012 Dyno results.jpg |
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mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
Kelly's pic is not showing. Here is the thread.
[forum.britishv8.org] Good HP at the wheels and max TQ 700 RPM lower than the simulation. I used Rob's engine specs's for the cam comparisons. I picked the Performance Trends program because it doesn't show inflated numbers like some. Those simulations would be at the flywheel with open headers, electric water pump and no accessories. Typically chassis dyno's show peak HP and TQ 500 RPM's lower than engine dyno's. Deduct 20% from the engine simulations above to get approximate @ the wheels. Edited 3 time(s). Last edit at 11/17/2017 11:40AM by mgb260. |
rficalora Rob Ficalora Willis, TX (2764 posts) Registered: 10/24/2007 02:46PM Main British Car: '76 MGB w/CB front, Sebring rear, early metal dash Ford 302 |
Re: Gear ratio calculator, rear gears, and transmission ratios
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rficalora Rob Ficalora Willis, TX (2764 posts) Registered: 10/24/2007 02:46PM Main British Car: '76 MGB w/CB front, Sebring rear, early metal dash Ford 302 |
Re: Gear ratio calculator, rear gears, and transmission ratios
Jim - do the simulations change if you assume my motor but with the Edelbrock Pro-Flo EFI system? It has a different intake & of course throttle body vs. carb.
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mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
Rob, It may, but generally equal carb or fuel injection show very little difference. What you will notice is better throttle response, easier cold starting with no warm up and better mileage. I would need the specs for injectors and cfm of throttle body, TBI or port injection and I'll run it to see.
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mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
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mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
Fuel injection is very tuneable. I think if you change timing and A/F mixture you would increase HP and lower TQ a bit. I'm going to show that last chart again in a different scale and by itself so it is not cut off.
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mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
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rficalora Rob Ficalora Willis, TX (2764 posts) Registered: 10/24/2007 02:46PM Main British Car: '76 MGB w/CB front, Sebring rear, early metal dash Ford 302 |
Re: Gear ratio calculator, rear gears, and transmission ratios
Great info Jim!
I just talked to Comp Cams & they recommended their XE266HR -- pretty close to what Kelley had. Thoughts on 266 vs 264? Looks like I'm down to one of those or the E303 (which is about $100 cheaper). |
mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
Rob, Or advance your cam 4 degrees for free. I can run the XE266HR to see I there is any difference. I can do back to back carb and Edelbrock Pro-Flow fuel injected.
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mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
The fuel injection moves the power curve down for more TQ and less HP vs carb for more HP less TQ. I think A/F and ignition tuning will fix the HP to TQ ratio. The XE266HR doesn't seem much different to the XE264HR or the B303. It's higher lift probably isn't utilized by your heads and it would be a good idea to check piston to valve clearance. Most street engines don't need more than .500 lift. It has .544 IN and .555 EX lift. XE264HR has .512 @ both. B303 has .480 @ both and E303 has .498 @ both.
Edited 2 time(s). Last edit at 11/17/2017 06:01PM by mgb260. |
mgb260 Jim Nichols Sequim,WA (2463 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Gear ratio calculator, rear gears, and transmission ratios
If you wonder why I advance these cams 4 degrees it is not only to move the TQ curve down but also to get the Dynamic compression around 7. Straight up is only around 6.5.
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