<VV> Actual vs. advertised hp

[Tony Underwood]

At 02:30 hours 03/09/2005, you wrote:

>Tony,
>It seems quite apparent that you do not understand the differences between 
>SAE Net, SAE Gross and advertised horsepower ratings back in the pre 1975 
>days.


I do understand.   You just don't understand what point I've been trying to 
make.


>That seems to be the basic cause of your confusion.


Bob...  I am not confused.



>Although this is quite a lengthy discussion, I'll try to bring you up to date.

Regarding what?

>Back in those days, GM would run engine dyno tests (with their accurate 
>dynos, by the way)


...attached to engines which made more horsepower as tested than anyone 
else was ever able to reproduce with identical engines...

Think about that for a minute.


>with the engine configured exactly as it would be installed in the 
>vehicle. That is, with stock air cleaners, stock mufflers, with cooling 
>fan operating and accessories installed.


This would be NET horsepower.   Measured as installed with all accessories 
attached and functional.   The Corvair engine was one of the few out of 
Detroit that was required to be measured in such a configuration due to its 
cooling requirements.    But...  GM fudged the specs after the fact.


>The torque and hp numbers were then corrected to a temperature of 100 deg 
>F. That temp was selected since it represented a typical under the hood 
>real world temperature. The resulting numbers were the Net HP and TQ, and 
>were know as the "as installed" hp and TQ. These are the real numbers! 
>This is what the engines really developed.  This was the flywheel horsepower.


Agreed.   So what's the problem?   (other than their being considerably 
lower than what was claimed by GM, much like everyone else at the time for 
most engines)


>For the 80 hp, they were lucky to get 65 real hp (yes, 65hp! ).


I saw a report somewhere that the 80 hp engine made appx 70 real hp, give 
or take a couple either way...   However, I do NOT recall the source; was 
something I read.   That actually sounds about right considering how the 
engine actually performs.


>For the 110 engine, 88 hp was it. For the 140 engine, 109-112 hp was all 
>that was put out by those engines. If you don't believe these numbers then 
>all I can say is that you have some serious problems.



Bob...  those are the figures I was waving  around to begin with.  I have 
ALWAYS believed them.   What gave you the notion that I dispute them?   My 
entire POINT here is that the engines do NOT produce advertised horsepower 
and never did.   Thus, relying on those same factory advertised horsepower 
and torque specs for comparisons between engines when you KNOW they're not 
quite right is shooting yourself in the foot.

You seem to have missed my entire point.

I stated that the HP figures that were advertised for these engines (among 
others) were HIGH and that they didn't make as much power as their 
advertised specs stated.

Again, where's the problem?


>GM then repeated all of these tests, but with no air cleaners, and and no 
>mufflers, but with a lab exhaust system with some vacuum pulling the exh 
>out. They also ran these tests by separately measuring the hp that the 
>cooling fan took and ADDED this hp back in to the measured engine output! 
>Thus the resultant output eliminated the power consumed by the fan. Then 
>they corrected all the data to 60 deg F, which had the effect of raising 
>the hp since engines work better with 60 deg air than with higher 
>temps.  This data was called the SAE GROSS hp and TQ. We know that these 
>numbers are much higher than the net figures. So for example the 140 hp 
>engine developed 138 gross hp max!

And, that's not real world horsepower.   My comments revolved around GM's 
fudging on HP ratings in order to prop up a rather meagre statistic to make 
the engines look better on paper.    Nobody runs an engine with the exhaust 
vacuumed, no cooling system, no accessories etc.

I am aware that other manufacturers also rated engines via the gross HP 
method in those times, always been common knowledge.   However, the figures 
got juggled around even then, sometimes underrated, sometimes 
overrated.   Everybody had an agenda of one sort or another.

Once again, I would say:

I'd really like to see genuine real world dyno pulls on Corvair engines 
WITH the fan and alternator belted up and with air cleaners installed and a 
factory exhaust in place.

THEN, run the plots on the torque curves of a 110 and then a 95... and see 
THEN which one had a broader low end torque curve.

You'd need to run an independent test to know for sure because it's no 
telling what to expect from attempting to use GM's original specs because 
they simply are not accurate.    By the way, most engine folks today do NOT 
use any factory specs in rating an engine that's been rebuilt to 
blueprinted specs.   They dyno it themselves to  show a customer what 
they're actually getting.   With GM's 1960s specs, one never could be quite 
sure...

By the way:    Chrysler's performance engines of the '60s had such a well 
designed air cleaner system that the engines actually dyno'ed out a few HP 
LOWER if the engines were tested without the air cleaners 
installed.   "Dandy" Dick Landy ran a stock class Dodge Dart in pro drag 
racing and he ran it with air cleaner installed.   People thought he was 
batty; he turned quicker times that way and other Mopar racers began 
running air cleaners on their race cars as well.

Unfortunately, Corvairs didn't enjoy a flow-tested air cleaner 
system...  so running without an air cleaner, particularly that restrictive 
snorkel, would well kick a couple extra HP out the flywheel.

By the way...  some of the savvy Ford and GM street performance types were 
running 383/440 Magnum air cleaners on their GM/Ford performance cars.


>But now the advertising dept got involved and bumped the gross hp numbers 
>up to something they felt would make their cars comptitive and attractive. 
>Thus the 140 engine now became 140 advertised hp.

In other words, GM lied.   Is that not what I said...?   Again, where's the 
problem here?


>So if you expect that a 140 hp engine is ever going to put out a real 140 
>hp in stock configuration you are fooling yourself.

Again, I never said it did.  I said it produced LESS than its advertised 
horsepower... several times.    Problem...?

Where are you going with this?   I started this thread out by saying that 
the GM advertised HP/TQ specs on Vair engines were embellished.


>You should read about the RST Yenko Stinger engineering team that reported 
>they had a heck of a time getting the 140 engine to put out an actual 140 
>hp even after all their mods.

They're not alone...  others have had trouble doing it as well.


>You apparently are confusing advertised hp with something real.

No I was NOT.  Sheesh, I've been bitching the whole time about how GM 
advertised more HP than the engines could produce, all the while 
here.   Did you get switched around or something?    I have *Always* 
maintained that GM claimed more than what was there.


>Never happen. Even the gross hp numbers are a lie since no one is ever 
>going to test or run a car with no cooling fan to get real world numbers.

...I thought I said that already...  twice.


>You have got to use the net numbers.

EXACTLY.

Now:   What ARE the net numbers?   Are they correct?   Where did they come 
from?   Which numbers (gross or net) were used to arrive at the current 
published torque curves for the 95 engine which have been bandied about as 
evidence of the 110 engine's supposed superiority over the 95 in "almost 
all areas"?


>If you run any tests today, you need to make appropriate corrections.


NO, you would NOT.   You run the engine with accessories, air cleaners, and 
fanbelt/fan/alt-gen installed and you measure at the flywheel.   THAT will 
give you the real world horsepower and torque figures and that's the 
measurement you use to determine what the engine will actually do.   No 
need for any corrections when the engine is measured thus.

This is why I keep saying that I want to see REAL dyno tests of the engines 
as installed, no embellishments or "advertised ratings" lies.     I keep 
hearing about how GM's specs show that one engine is "superior" to the 
other which kinda flies in the face of rationality when those figures are 
known to be inaccurate.


>If you want any corroborative engine dyno test data, please refer to Hot 
>Rod mag, August 1975.

I believe this is where I may have read some of the independent dyno 
tests.   I recall the tech people doing the work complaining about how Vair 
engines turn backwards making them difficult to attach to many dynos 
etc.   But I digress...



Bob...      I believe you have mistaken what point I'd been trying to 
make.   Your comments above have, in a round about way, confirmed what I'd 
been trying to say all along, that GM embellished the HP ratings on the 
Vair engines, as well as other engines, in order to make a better selling 
point for the particular application in question.

THIS MEANS that those figures we see in various GM publications regarding 
real world horsepower are NOT correct.   That was my point.

This has been a given for decades...   so if you quote those same figures 
as evidence of one engine' advantage over another, you can come to some 
erroneous conclusions.


>I hope that this will bring you up to date.

...OK...

Now,  what does all this have to do with the original thread... that of how 
the 95 performs better and feels stronger at low speeds?    Could it be 
that the 110 engine's specs might have been fudged a tad so as to make it 
appear stronger on paper than it really  was...?


Thus, back to the original thread.


tony..