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-   -   hp versus torque (https://www.germanlook.net/forums/showthread.php?t=6694)

oasis October 31st 2005 15:34

hp versus torque
 
Wow, 32 people viewing this sub-forum ... Anyway, ...

I have heard, "People buy horsepower; people drive torque."

I have seen calculations where HP and torque are related by RPM's and some factor of 5252 (or 1/5252 depending which way the formula goes).

I have (water-cooled) a 2.0 ("two-point-slow"), a 1.8T, and a TDI. The TDI has less HP than the 2.0 but nearly the same torque as the 1.8T.

I have seen HP numbers bandied about with Type I and Type IV engines.

What makes an engine more torquey? Why are certain engines more prone to being torquey?

I have read the passages on the Subaru conversions (thanks, ricola, for the link at all who have contributed to the main current thread), and it seems way too involved for my skills and beyond the scope of anyone I know.

I am still leaning towards a Type IV but I am still trying to justify the initial cost over a fancy Type I. (I understand many of the advantages of longevity, etc. I am more interested in understanding the HP v. torque dynamic.)

beetle1303 November 5th 2005 22:46

this should justify your last question:
In a very simple and not at all scientific way:
torque is what you feel when you step on the throttle/gas from standstill
and
Hp is the engines ability to make the car travel at a given speed

Anyway torque is what makes your car going.

read:
http://auto.howstuffworks.com/question622.htm
and
http://auto.howstuffworks.com/horsepower.htm

There are many factors that can make an engine "more torqueier" than others

Consider this: fitting larger valves on an engine will improve top end hp
example: 1776 cc t1 with o44 heads and the same engine with 040 heads. The second one will produce more torque and less top end power.
Main factors:
Configuration ( in-line, V, boxer)
Displacement
Camshaft (timing, duration, lift)
valve train(stock 1:1, 1.25:1, 1.4:1 etc)
fuel supply and type (single carb,two singles, twin carbs fuel injection)
Induction (forced-NA)

thats pretty much :p

Also something that can differ the torque feeling is the gearing...

Chris

oasis November 7th 2005 05:07

Thank you very much. A lot was answered and understood. :)

73notch November 7th 2005 15:33

thats why you turbo, you get tons of both.

oasis November 7th 2005 21:13

Quote:

Originally Posted by 73notch
thats why you turbo, you get tons of both.

Why turbo-charge rather than supercharge?

I've done some research for my 2002 Cabrio with the very reliable and undynamic 2.0. The power bands I have seen with supercharging look more similar (although obviously greater) to stock than different configurations of turbo-charging. Plus, there is no need for an intercooler and no turbo lag*.

(* - For the record, I experience no noticable lag with my wife's TDI which I love, but I find the lag in my dad's Passat with a 1.8T very disquieting. Once the latter kicks in, it is nice but it seems so undecided in normal day-to-day driving. I wouldn't want that profile for my Super.)

oicdn November 8th 2005 08:33

Supercharging is BRUTAL on the bottom end. Rather than a ramp up in the power curve, it's all instantaneous as soon as you hit the throttle.

Although nice, the versatility isn't there. Takes power to make power. You have more options with a turbo, and is a friendlier in terms of configuring/customization.

I'm a turbo guy...I've thought about supercharging in my ricer days, and couldn't justify the cost on the minimal power. And the idea of a belt/pulley determining everything was somewhat unsettling....simpler, but it's just lacking the RAW power a turbo has....

oasis November 9th 2005 11:28

I'm not against turbo. I will go that route with my Super using a Type I or a Type IV if that's better than supercharging or a proper naturally aspirated larger displacement.

All I do know is the 1.8T is schizo with its spooling in normal driving and has a noticable lag when you need to punch it to get around Grandma Moses. I want the instantaneous response and that is why I will go with supercharging with my Cabrio when the time comes.

Versatility is not an issue with me. I want to set it and forget it regardless which of my cars we're talking about. I don't want to be constantly tuning and adjusting.

I regularly maintain all of my vehicles every 5,000 miles. I know some people change their oil every 3,000. Nothing is wrong with that. My system has served me well through four Fords, a Fiat and eight (I think) VW's. All reached 100,000 miles before being sold or needing a rebuild. In fact, only two needed a rebuild. My Jetta at 300,000 when I sold it and an Econoline van at 120,000 when I sold it. My Super will probably need one in the next 10-15,000 miles.

Those are my desires. What engine and whether there is forced air or not by any means is what I am trying to figure out so I can make plans accordingly.

I appreciate all of the responses and opinions -- especially from all of you here because you know more and you have been there and done that. This is my first foray.

beetle1303 September 7th 2006 12:29

as oicdn said, a supercharger is brutal on the bottom end (bearings mostly and bearing seats on the case),
and takes power to make power, that's why the relatively low power gain.

Now if properly designed and mostly calculated, both systems can perform similarly.
That said, IMO(from a longevity point view) a supercharger will be best suited to easy but fast
(linear kind of driving) around town, while the turbo for more spirited driving
(more racy, with many and sudden throttle changes etc)

Both systems can produce high hp and torque numbers. The limiting factor of the turbo will be the flow of the
compressor side
Example:the vag 1.8t when revved hard, above specific rpm the engine losses power before
reaching the limited rpm range. this means that the compressor cannot flow more air (which is produced on the
exhaust side due to higher rpm)

While the limiting factor on the supercharger while be the Continuous Variable Gearbox of the belt.
Because in this kind of application, boost is produced from very low rpm, just over idle when the throttle is
opened. If the gearing of the belt was static (constant), the boost level would rise and blow the engine apart.
There is this smart device called the CVG that reduces the gearing on the charger side of the belt.
The thing is what is the higher and lower gearing achieved and what is the rate of descent ("lowering rate").

If major tuning is going on both systems will require a suitable intercooler (air-air/air-water)
to keep intake charge temps down.

Gearing plays a major role in satisfactory driving performance and if done properly will complement any engine
(NA/Turbo/Supercharger), although the two later systems will need a little wider gearing to properly utilise
their increased torque output. On the other hand if this is overdone a turboed car's performance will suffer
from severe "turbo lag".

Both systems are boost-wise fully customizable, while the turbo offers more versatility in the mounting/routing
aspect of the modification.

My ideal config would be a fully forged 2.0L t4 with a t04 garret ball bearing turbo, custom header, custom manifold, charge cooler (air-water)2 twin throttle bodies, 2 intake plenums and standalone efi system with ignition control
Gearbox...dunno yet something to be able to hold 400hp and 45-50 kg/m
Just my 2 cents...

Chris


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