Hi, i have heard people mention that you lose hp from using a 2 speed powerglide? Is this true? Any info would be great
A power glide has a higher first gear than a 3 speed, giving sluggish acceleration in comparison (stock applications)
It DEPENDS... To answer your question...NO...you will NOT...loose...horse power with a properly rebuilt Power Glide transmission. You'll find that a LOT...of drag racers, still use the Power Glide trans. Behind, up to and well over 1000hp engines ! With that said, a lighter car and a little more horse power is required...IF...you use the stock transmission gear ratios. Yes, a good rebuilder can change the gear ratios in the trans. Just to make clear, a car takes torque to get it moving...right ? With the Power Glide only having two gears, you'll need more power to get a car moving "quickly" with a two speed trans than with a three or four speed trans. But again...NO, you will NOT...loose...power with a Power Glide. They are actually a fairly efficient trans., internal lose wise. **If you have a cruiser, with 3.50 (or lower) ratio rear axle ratio, that you aren't racing around town with, a Power Glide will work just fine. **But if you are going to be hitting up your local drag strip, have a 3.50 or so ratio axle gear and you have a somewhat normal 300 or 400 horse power engine, then yes, a three speed trans. WILL get you moving faster. Hope that helps a little. Mike
No, actually powerglides out of all the racing transmissions used have the least parasitic loss of power. Less stuff rotating internally. And hi gear is still 1:1.
Thanks for that information mate. I am aware drag cars still use them and dont deny their reliability and toughness. I love my powerglide
Ok fair enough mate thank you, was only asking as i brought a new 350 chev and was advertised at 380hp and it pulled about 230hp at the wheels
No. A power glide actually takes less power to run, 22-25 vs 35 for a turbo 350(quick Google search) a Dyno measures at peak rpm. High gear ratio remains the same as 1:1 where your measuring on the Dyno.
What it will do on an engine dyno and what it will do on a chassis dyno is like comparing apples to anchors. Yea, they both start with A but that is where the similarities end.
Drivetrain loss from transmission, rear axle, and loss from accessories such as fan, water pump, power steering pump, air cleaner restricting flow, street carburetor all add up. 230 to the wheels isn't too bad for a 350.
Dyno operators can add or subtract horsepower depending on how the car is positioned and how the dyno is set. Dynos work very well for tuning if the car is never removed from the rollers, once removed, the next set of tests should not be compared to the first, and you can't compare numbers from one dyno to the next. As an example, my uncle ran across a deal for a free electric water pump and cooling fan if he would dyno the car before and after the parts were changed to show how the electrics made more power by way of less drag on the engine ( 455 Pontiac in a '66 GTO ) They ran the car before any changes were made, changed out the water pump and fan on the dyno, then made a couple more pulls. As we expected, no noticeable power was gained, but the engine ran hotter due to slower water circulation and less air movement. They dyno operated offered to move the car " up " the rollers and make a few more pulls. The first pull setting higher on the rollers netted more HP, so on the second pull they aired up the tires well beyond normal racing pressures and low and behold netted even more HP. The electrics didn't gain power, it was just easier to turn the rollers setting on the peaks and not climbing up them.
Automatic transmissions use power , the convertor , the front pump are the biggest culprits ,but yes , automatics cost power .
Lock-up Powerglides exist, but they are specialized racing pieces, not plentiful and not cheap. Otherwise, you're stuck with converter slippage, i.e. turning horsepower into heat.
Everything that transmits power from the engine to the ground consumes some power. All the bearings, gears, even the tires themselves consume power. In fact, the internal friction of the engine consumes power. If you are racing and power is the big thing (it almost always is) you want to chose components that consume the least amount of power.
Plus that was most certainly crankshaft HP,big difference from Rear Wheel horsepower Plus , Dyno's LIE !
I can understand a bit more HP with the tires pumped up due to less rolling resistance. I question the "up the rollers" deal making any difference.
These guys have it all laid out for you. Advertised power numbers are not guaranteed. Engine numbers are not directly related to chassis numbers, they often cite a percentage loss that is based on experience, not math. Chassis dynos can easily be 'fudged' to show what they want. All dynos use various methods to measure torque, then extrapolate HP numbers. None are directly comparable. If you think they are a direct measure, like a tape measure, they are not. It's more like using your eyes (instead of a meter) to say how bright a light is in different conditions on different days. Go over to youtube and search for "fake chassis dyno numbers". There are enough different videos to explain what's going on. The trans will cause some loss due to convertor slipping and frictional loss. Replacing a 'glide with a T350 for example would not get a jump up to the advertised number, if all other things were equal. Bragging dyno numbers is not useful except in contests for that specific thing. Engine Masters for example. An engine tuned to get a high number might not perform well in a car on the road, because they tend to be peaky to get that high number at one RPM rather than a good, broad torque throughout operating range. You are experiencing something that is typical, a lower than expected 'number'. The true test is does it start, idle, accelerate, and provide performance that you like while returning MPG that also is up to your expectations.
^^^This! A buddy of mine bought one of the new COPO Camaro drag cars from Chevrolet. Basically a BIW (body in white) but ready to go racing right out of the box. They come with no air bags, one seat, no interior, roll cage, thin glass, no VIN, engine of choice...and a power glide. Oddly no tranny brake but that can be fixed.
anything between the crank and the asphalt robs torque. It is called parasitic loss. Some things rob more oower than others.
The key to overcoming the higher low gear, is higher stall converter. Doing so will use up ponies but at the same time produce more for the launch.
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