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MG MGB GT V8 Factory Originals Technical - rear end
|Before I spend a lot of money on a different rear end what harm can it have on my engine when its running at a higher rpm at 70 mph.I dont know much about engine life but someone must know if this will produce any engine ware.My engine is as follows 3.9 rover stock 4 barrel intake, elderbrock carb,Isky 262 cam,RV8 headers,stock heads Im guessing maybe 200 HP. Thank You|
|D B W|
|Forgot my transmission is a Rover with .83 fifth gear.The statement I made about engine ware I really ment does the high rpm cut the engine life short.Instead of lasting 200,000 miles it might last 100,000. If that would be the case thats alright.|
|I don't think engine wear is as much of a consideration as how annoying it gets. I drove about 500 miles round trip on Saturday and it really got annoying by hour #4 to be at 3500 rpm's. I'm switching to IRS with 3.27:1 gears this winter.|
|Justin I have the Miata seats with the speakers in the headrest and all you really can hear is the radio.|
|The gas mileage gets annoying....|
|My experiences with fuel usage has been that different ratios have litte effect, as do larger engines, if the vehicles are driven identically. The problem there is that with lower ratios (numerically higher) one has to be lighter on the throttle. I've had engines with 100 cubic inches more displacement than the stock engine deliver the same economy without any final ratio changes unless I elected to use the extra power, at which point I could expect to get half the economy of the stock engine. The reason for this is that it takes about the same amount of fuel to deliver a given horsepower regardless of engine size or rear end ratios, and the same horsepower is required to maintain any given speed. That said, engines do have a sweet spot at which they are more efficient.|
|The sweet spot that George refers to is the cam rpm power output match to the final gear ratio, that would be your cruising rpm on the hwy therefore the gear ratio should be matched to the cam output.|
My 96 Vette 350 LT4 335 hp 6 speed got 27 mpg avg from Ca. to Nashville and back The final gear ratio is 3:42 in 6 gear at is doing 2000 rpm This engine develops lots of torque and there is no need to shift as often.
it runs in the bottom of the the torque peak.
2.8 V6 180 hp V6 5 speed got 23 mpg on a 250 mile trip with a 3:90 final drive, the B ran right at the torque peak of the cam, It makes the car alot more fun to drive when everything is match.
But who cares about gas mileage!
|I am not worried about the gas as much as the engine can some one help me with the question from the first thread. Thank you This is all about not having any money left to do the rear end other wise I would go with the 3.27 ratio. DBW.|
|I believe it's been answered. The engine life won't be significantly altered either way.|
|Don't worry about it! It should be good for a very long time|
|Thank you for putting my mind at ease. DBW|
This thread was discussed between 27/08/2003 and 28/08/2003
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