MetroMPG.com mailbag: VW Polo transmission swap not very successful
Got this interesting message from a visitor commenting on the tranny swap I did for the taller final drive (MetroMPG.com post ... EcoModder discussion).
His transmission swap didn't return the expected results. He figures it dropped the engine too far out of its best BSFC range at cruising speeds (sounds like he cruises fast, @ high loads): http://tbn0.google.com/images?q=tbn:...%28Side%29.jpg Quote:
|
Sounds to me like he needed to add some aero mods to reduce the load at those crazy high speeds. I'm suprised it could even go that fast with that high of gearing.
|
Indeed, I think if he could reduce the load a bit he might be better off.
Sad to hear since the Polo is such a sweet ride. |
There are 4 different gearboxes that will fit the 1.0/1.3/1.4s all range from 'city' boxes for the 1.0 to 'bahn' boxes with stupid tall ratios for cruising (30mph/thou)
Personally I'm looking into getting a bell housing from a 1.6 much taller cluster throughout and then puting the 1.9 diesel sedan top cogs and final in it :D |
IIRC,
Gasoline engines are at their peak efficiency at wide open throttle. If the factory tranny kept it loaded and floored at 70mph then it was on its most efficient spot of the curve. Changing the gearing pulled it off peak. I wonder what the MPGs at a higher speed would've been? |
mine will cruise at 90+ (cough-where legal limits allow;) )and still return 30MPGus
|
Its about torque/ per rpm.
He pushed his engine very far outside of that. There is still plenty of power but not much useful force for every increased TP. For example as he reaches 50 mph in (I guess) 4rth he was at peak FE as far as the engine was concerned. Putting in the least amount of fuel to get the most torque. Any higher and its not available so you have to stack and push further. |
All times are GMT -4. The time now is 10:11 PM. |
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com