MG MGB and MGB GT Tech Talk
I think it would be good to know how other MGB's perform. My 76 cruises at 65mph at 3500 rpm's. Is this within the range of other B's. Also I am interested in what others do at 3000 rpm's through the gear range. This information would be helpful for many I am sure
65mph(3200rpm) roughly with O/D, so I am assuming you have an O/D? If I recall, you would be spinning roughly around 4000rpm at 65mph without O/D.
I have no overdive and would be turning near 80 at 400rpm.
I was turning 4200 at 70 before OD. Now I barely under 4 grand at 80.
mine shows an INDICATED road speed of 80-85 mph with the engine RPM indicating about 3500... i have a 78 B w/OD, but my engine has been warmed ( altered) a bit...it keeps with the flow of traffic, and even sometimes is faster...
Barney, Either your or my tach or speedo is off. I know it's not my speedo as I've clocked it on Interstate mileposts a few times. I have a '78 with OD also, check my other post for my numbers. 70mph=51.4 sec, 75=48, 80=45 sec.
thanks for the mph and times.. as soon as i can break away from work, with some daylight , i will look at the times.. i kinda fiqured it may be off some, as that is why i always mention INDICATED speeds...:o)...
but one thing i do know, is i love the way it runs, and the mid range torque it has...
can't ya tell i am excited..? lol
5000 or so at 65 MPH (had the speedo rebuilt and adjusted for my car). Wonder if my tach is off (never tested that!).
Is there a gearing difference in newer MGB's?
All B's in forth gear should turn 17.9 mph / 1000 rpm, assuming stock size tires and the standard 3.909 rear end ratio. If overdrive is engaged, then you should be turning approximately 22 mph/1000 rpm, there are two overdrive ratios, .81 and .82 I think, but they'd both be close to 22 mph/1000rpm.
If you are indicating significantly off from there ( as some of you have indicated) you might want to check to see what up.
If you've gone to one of the oversize tires (185/70x14), your ratio between the speedo and tach would remain the same, but you true speed would be about 3% higher than indicated.
H.
Yeah, it runs just about like I told you it would, doesn't it?
it does.. torque enuff to pull the mountains , and pass semi's on the road... starts easy, idle a bit bumpy, revs freely...and good gas mileage for the trips..
i am impressed, as i have a 95 VW, 2.0, FI, and the MG gets about the same amount of mpg as the VW.
My car shows 96 mph at 5800 rpm. In my mind that doesn't seem right if you calculate all the ratio stuff. Also its non OD
That's about right. You got to reolize these speedoes and tachs in the MG's are a + or - situation. If you took a speedometer out of ten MG's and tried them in your car there is a good chance you would get ten different readings. Besides 90 mph will get you a ticket and or killed just as fast as 100.
I am not sure how you figured your math, but your real life cockpit indications sound pretty close to me. These are the calculations I came up with.
17mph per 1000rpm for non-O/D
5800rpm/1000rpm=5.8
17x5.8=98.6 mph
as you said, your turning 5800rpm at 96mph.
You can easily chalk the 2.6mph up too speedometer error. Typically speedo errors become more prevalent at higher speeds.
