I’ve been immersed in the air-cooled Volkswagen world for decades, ever since my dad’s old ’68 Beetle enchanted me, and have been consuming air-cooled VW content ever since. I’ve owned three Beetles, a band-aid-colored 1968 one, a 1971 Super Beetle, and a 1973 Beetle, which I still have and which was sorta-famously stolen and recovered. I read anything air-cooled VW-related voraciously, and I’m telling you all of this because you need to understand why I’m so baffled by this: the way the whole community seems to talk about Beetle engine horsepower is weird. Specifically, I have never seen a good, easily understandable horsepower number for 1975 and up fuel-injected Beetles. It’s all a little weird, so let me explain.
I actually discussed this with a friend very well established in the VW community, and he agreed. For whatever reason, fuel-injected VW engines get sort of ignored, which I think is strange. For this to make sense, I think we need to run through the official VW engine horsepower changes over the years, and I’m collecting these figures from an official VW What Year Is It brochure, specifically the 1977 edition I happen to have on my desk here.
The Problem
Well, it starts at 1949, so I had to get the earlier numbers from other sources, but they’re widely agreed upon:
1938- 1940: 985cc, 22.5 hp
1940-1953: 1131cc, 25 hp (originally developed for Schwimmwagen)
1954-1960: 1192cc, 36 hp (some sources list as 34)
1961-1965: 1192cc, 40 hp
1966: 1300cc, 50 hp
1967-1969: 1493cc, 53 hp
1970: 1584cc, 57 hp
1971-1974: 1584cc (but now with a dual-port intake manifold), 60 hp
1975-1979: 1584cc (but now with Bosch L-Jetronic fuel injection), 48 hp (SAE net)
See that last entry? That’s the issue. In 1975, VW finally switched from carbureted engines to a fuel injection system, and they must have been very proud of it, because they actually deleted their own name from the rear of the car to replace it with a badge that read FUEL INJECTION:
Keep in mind, that was the only spot on the whole car that actually said the name VOLKSWAGEN on it, so replacing it with this technical detail was a pretty big deal. So, if injecting fuel is so great, why does the brochure seem to suggest that doing so caused a 12-horsepower hit from the last time horsepower was increased? I mean, look, here’s 1975:
…and here’s 1971:
1971 has a ravenous 60 hp, and then come 1975, we’re back down to 48 hp, which hasn’t been that low since before 1966, when the 50 hp 1300cc hit the scene.
Why did this happen?
Now, there is some indication of what’s going on, as 1975 says the power is increased from 46 hp to 48 hp, and then says (SAE net). What this is referring to is a different way of measuring horsepower, SAE net as opposed to SAE gross, which was the previous method of measurement. The main difference is that SAE gross horsepower was measured in such a way as to find a particular engine’s idealized power output. As such, engines were run without power-sapping accessories like alternators or power steering or water pumps, and without mufflers or air cleaners, and with optimized engine timing. In short, the figures did not represent how an engine would be run in the real world, at all.
As a result, SAE gross power ratings tended to be pretty optimistic, if not unattainable, and that’s why so many ads for mid-60s muscle cars had stratospheric 300+ horsepower ratings that were really little better than pipe dreams.
SAE net attempts to bring a little more reality to the measuring of engine power, and as such requires all of the engine’s accessories and equipment that would be in place for the final product to be present in the test. Honestly, for a VW Beetle engine, this isn’t all that much, as the only belt-driven accessory on a Type I VW engine is the alternator and the engine fan, which share a common shaft and are driven by a lone belt. For many other cars, the drop in power when measuring the bare engine of SAE gross and the more reality-equipped engine of SAE net was shockingly significant: the over 8-liter engine (500 cubic inch) from the 1970 Cadillac Eldorado made 400 hp when measured by the SAE gross standard; the same 500 cubic inch engine in SAE net ratings in 1971 made only 235 hp. Ouch.
The switch from SAE gross to SAE net generally happened for most carmakers around 1972, which makes Volkswagen’s sticking with SAE gross numbers until 1975 even stranger. California required SAE net ratings in advertising in 1972, which helped to force the adoption of SAE net ratings all over America.
The excellent site Ate Up With Motor explains the differences like this:
“Gross output, which in the U.S. is typically measured using the methodology laid out in SAE standards J245 and J1996, is the output of a ‘bare’ engine running on a test stand with no external engine-driven accessories (e.g., alternators or water pumps), free-flowing exhaust headers with no mufflers, and optimal ignition timing. Gross ratings are also mathematically corrected for standard atmospheric conditions. In other words, gross output represents a particular engine’s maximum output under ideal conditions.
In the real world, automotive engines very rarely operate in ideal conditions. The engines of most cars are burdened with various engine-driven accessories, including the engine’s own water pump and generator/alternator and add-ons like the power steering pump and air conditioning compressor. Engines intended for on-road use typically also have restrictive air cleaners and exhaust systems, sound-deadening mufflers, and emissions-control add-ons like catalytic converters and thermal reactors. Engine tuning is further compromised in the interests of reduced noise, better drivability, improved cold-weather performance, and lower exhaust emissions. All of these factors reduce the engine’s maximum output in ways that the gross rating methodology does not reflect.
For that reason, the SAE and similar bodies have also established standards for measuring net output. Net ratings, such as the ones defined by SAE standards J1349 and J2723, are still taken with the engine on a test stand, but reflect stock ignition timing, carburetion/fuel delivery, exhaust systems, and accessories. The specific methodology varies depending on the specific standard being used, but the gist is that a net rating is a closer approximation of an engine’s output as actually installed in a car or truck.”
So, with this all in mind, it’s not surprising that VW eventually made the switch, but I don’t understand why in brochures like this one, published in 1977, VW kept all of the old ratings in SAE gross over the years, which made it look like horsepower dropped for their most recent models, which it did not.
In fact, I have yet to find anywhere online where people have at least tried to convert the 48 hp SAE net rating of the fuel injected Beetles into the old SAE gross format, just to give an ability to compare apples to apples, even if those apples have their accessory drive equipment removed. Like, I’d love to know how much more power fuel injection added to the old VW engine! Why have I never been able to find this anywhere? That’s what gets me.
Time to do some math
I think we can at least make a good guess here; there’s not really one set formula for converting SAE gross to SAE net or vice versa because there are so many specific factors based on the engines themselves. The good news for us is that if we want to compare the carbureted 1600cc engine with the fuel injected 1600cc engine, they’re pretty much identical except for the fuel delivery system.
So, if VW rated the carb’d 1600 at 60 horsepower SAE gross and 46 SAE net, then it seems that the SAE net power is 76.667% of the gross rating. So, if we use the same percentage of power reduction, then it appears that the 48 hp SAE net fuel injected engine comes to about 62.6 hp SAE gross. For fun, let’s just round that up to 63 hp.
As someone who grew up thinking that 60 hp was the highest power Beetle one could buy in America, this feels like a reveleation. Why is this not talked about more? Plus, the top speed increased from the 60 hp Beetles, from 81 to 84 mph! 84 mph! Why, that’s almost 85 mph, only sixteen miles less than the wildly optimistic speedometers of that era claimed:
That’s dreaming, of course. You’d need a hurricane-level tailwind, I think.
The fuel injected VWs tend to get ignored by the VW community in general, and that could be why no one has bothered to convert the power ratings into numbers that would let you compare with the rest of Beetle history, I think. But I think it should happen! Converting all the engine ratings from the pre- 1600 engines to modern SAE net ratings would be more difficult, as I don’t have the benefit of a VW-sourced Rosetta Stone like we have with the 1600 engine.
Is this worth pursuing?
Is it a project worth doing? I have no idea. Have other communities spent time de-rating old engines to the new common standard? On engines that generously made 36 or 40 hp, is it even worth it? And why does the whole VW community informally call almost any 1600 engine a “50 horsepower” engine? Is that number just considered close enough?
It’s likely none of this matters, but as a kid that drop to 48 hp in that brochure always drove me nuts, it was so baffling. VW could have included one parenthetical to say (63 horsepower SAE gross, like every other number in this fucking brochure). I would have appreciated that, and dreamed about how the raw power of sixty-three air-cooled horses would have felt under my foot.
So, even if it seems to be nowhere else on the internet, now it’s here: in SAE gross horsepower ratings, the kind used by Volkswagen since the introduction of the Beetle to America in 1949, the 1975 to 1979 Volkswagen fuel-injected Beetles made 63 horsepower. There you go.
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This makes appreciate the added power of the water cooled engines. My 78 Scirocco was making IIRC 73hp SAE net to move a sub 2000lb car. They were so light SCCA Production Class required ballast.
Loved this deep dive! Makes miss my high school ’63 with the canvas roof, 5 shades of red, 6 volt electrical system that required a push start at anything below 60 degrees.
A couple thoughts:
As others have said, the cooling fan is a huge power suck. Yes, really no accessories to speak of, but that fan works hard and generates drag at an exponential rate as revs rise (ok I made the “exponential” up. Maybe it’s a linear rate, but still.). Also, stock air cooled beetle exhaust was wildly restrictive, with those little twin pipes that chirped. (It bears repeating that gross hp was measured without the exhaust system). Why do you think so many people installed a glasspak (like me)? And finally, max hp in a gasoline non-turbo engine requires revs, at which point those pea shooter exhausts are really clogging up the works.
In conclusion – I think the hp drop from gross to net is entirely believable given drag from the cooling fan + restriction from the stock vw exhaust.
Jason, In addition to mixing up net and gross (SAE) hp ratings, you’re also mixing up SAE gross (US) and the German DIN PS rating, which was a net rating, and is usually within one or two hp to the SAE net rating.
The original KDF 985 cc was rated at 22.5 PS, as you noted. Since it was never sold in the US, there is no SAE gross number for it.
The 1131 cc was rated at 25 PS, but 30 HP (SAE gross. That’s the rating it had in the US as did all subsequent ones until the SAE net rating was introduced in 1972.
The 1192 cc was rated at 36 SAE, but 30 PS in Germany.
The 1192 starting in 1961 had 40 SAE hp, but 34 PS.
The 1300 was rated at 50 HP, 40 PS
The 1500 was rated at 53 HP, 44 PS
The 1970 1600 single port: 57 HP, 47 PS
The 1600 DP: 60 HP, 50 PS
The problem starts in 1971, because US emission controls started reducing hp ratings, but not the European ones, so there’s different ratings for each country.
In 1972, US required net (SAE) ratings, The 1600 DP was now rated at 47 HP. But the European stayed at 50 PS.
And the FI ’75 had 48 hp Net hp. Not much of an increase, but emission controls had impacted that significantly.
Instead of trying to calculate the gross hp of the FI, forget that, as gross hp numbers were always unrealistic; the net hp is the actual amount as installed in the car. So just use the European DIN net hp figures to compare, as they’re extremely close. That makes the 47 hp FI engine essentially identical to the highest carb DIN PS ratings, which makes gobs of sense, since FI doesn’t inherently increase hp per se, but allows the engine to be tuned to give more hp in a desmogged engine than would otherwise be typically possible. So the FI 1600 was essentially equally powerful as the best carb “dirty” European Beetle engines.
Hope this helps. Mixing up SAE gross, DIN, and SAE net can get a bit goofy.
The information you’re looking for is already available, no need to speculate! The German Bug manuals list net horsepower. For example, the 1963 German manual says the 1200 motor produces 34 horsepower while the US manual reports 40.
https://www.thesamba.com/vw/archives/manuals/1_63_bug_german/63t1_p78.jpg
https://www.thesamba.com/vw/archives/manuals/nov62bug/page78.jpg
There are two caveats though – Germans and all other non-anglos use metric horsepower (abbreviated PS in Germany, Japan, South Korea and possibly elsewhere), which equal 735.5 Watts, whereas US market cars use imperial horsepower which is 746 Watts (IIRC). 40 english horsepower thus equals 41 metric horsepower, and it’s why the 1001 horsepower Bugatti had 987hp in US and UK. A minor difference which is then compounded by additional minor differences between DIN and SAE net ratings; enough to upset Jason I should think. Not apples and oranges, but apples and pears perhaps.
Secondly, as American engine specs diverge from European specs on later cars, the power figures change too. Euro-spec carbed 1584cc Beetles from 1970-77 make 50 metric horsepower (DIN).
I have owned 2 dozen vehicles (not including the 4 motorcycles) including 2 VWs, 5 Jeeps, 3 minivans, 4 pick up trucks and somehow I have never owned an air cooled VW. The shame is real.
I owned a 2000 Mexi Beetle imported to the states via a 1968 pan. The Mexican owners manual declared 60 HP. BTW, the Bosch FI was pretty solid despite being quite antiquated for its day. The diag port was a 9 pin serial port! Load the software to a Windows computer and away you go. You did have to translate between Spanish, German, and a bit of English!
60 HP on a car from 2000! What are the Mexican Beetle interiors like. Is it basically the same as an old Super Beetle or were they updated?
Mexico never built Super Beetles, so they never got the updated dashboard design, just stuck with the black plastic 1968 dash until the end with the 2004 model year, but with a 1980s Jetta steering wheel.
The fan on an air-cooled car takes a lot of power. An old autocross trick on a Corvair is make your 30 second run without the fan belt. Not recommended but definitely fast.
From what I’ve heard from the few corvair owners I know, the fan belt will remove itself for you if you try to do any spirited driving anyway…
Hi Jason – nice meeting you at Amelia. You state the ’49 Beetle (the year of ours) makes an astonishing 36hp, but I’ve been lead to believe it’s 25hp. I asked the magical boffins over at ChatGPT and it spit this out:
“The horsepower (HP) of a 1949 Volkswagen Beetle depends on the model and the country it was manufactured for. However, as a general reference, the original 1949 Volkswagen Beetle, also known as the Type 1 or the “split-window” Beetle, was powered by a 1.1-liter air-cooled flat-four engine that produced around 25 horsepower.”
You’re correct! I screwed up my chart: 1953 was the last year of the 1131cc/25 hp engine, and the 1192cc 34/36 hp engine came in 1954. My apologies. You shouldn’t panic about having too much power now.
There was a time when VW and Rolls Royce had one thing in common. They described their HP as “adequate”.
They both also bragged in their US-market ads about the lack of annual styling changes.
So you are stating that a car manufacturer is stating performance figures at an ideal level as opposed to actual every day use? I cant believe this would occur. I mean sure in the USA MPG figures are a fucking joke. Donate $20,000 get 10 more mpg. Design it with a liberal logo get 20 more mpg. The facts and stats are all lies. But hey we are sure the governments climate and covid figures are correct despite being proven wrong. Yeah i believe todays lies because i believed yesterday’s lies. And will continue to believe the new lies otherwise people will think i am gullible
Actually he’s stating that manufacturers used to state performance figures that were idealised but unattainable in a car, but then changed them to power figures that are attainable in a car.
I design engines for OEMs. The published mpg is attainable by driving a real car the way it is driven in the test cycle. All cars use the same test cycle, so it’s a scientific method to compared mpg between different cars. But that mpg is attainable and even beatable in the real world, if you drive the right way and in the right conditions. If you use the performance, or live somewhere congested, or up a mountain, you won’t match the mpg.
You won’t match the stated top speed using quarter throttle up a hill stuck behind a truck, but people seem to expect the stated mpg regardless of how they choose to drive.
In summary: the facts are facts, measured by a test specification that is public domain. You can repeat the tests yourself and sue the manufacturer if it isn’t right.
I’m not an expert in climate or covid. I’m not sure they are relevant to engine testing.
I’m not an expert on internet blogs, but I’m 106% certain that anyone that has written a comment on one using the word “liberal” in a non-sarcastic way has never been an expert on the topic being discussed. Also I’m not an expert in statistics.
We don’t think you’re gullible. Just insane.
Wow, just wow. It would be fascinating to know how much bleach your mom drank.
I have a 1972 Super Beetle and I take issue with the 1600cc 60hp engine’s top speed of 81mph, as claimed by VW. Mine can hit 85 without too much trouble, even before I rebuilt the 200k+ mile engine. Could probably do 90 after the rebuild but I’ve never pushed it that far.
It gets even more fun when you list the Porsche 356 engines in parallel.
Don’t compare prices or discuss such things with certain folks though it causes MADNESS.
“And why does the whole VW community informally call almost any 1600 engine a “50 horsepower” engine?”
I informally call the 1585cc engine a 1600. 😉
And I call all of the dual-port 1600s “60hp”, ratings be damned. Yeah, I’m a rebel.
My family’s first car was a used 1956 Beetle. My father, not yet twenty, bought it in 1957 a few months after my world debut because a family needs a car. It was a black Sunroof Sedan. When I was two I was ejected through the open sunroof when my father had to slam on the brakes to avoid a collision as we rolled down a steep downslope. I’d been standing in the passenger seat. I landed on and rolled off the hood into the street, bruised but unbroken. This probably explains a lot about me. That Beetle remained our sole car until it was replaced by a new two-tone 1963 VW bus. When I look back, it’s hard to believe our then family of four took regular long road trips in a car that had 36 hp. gross! It would explain how long those trips took.
Canopysaurus:
When I was two I was ejected through the open sunroof …..I landed on and rolled off the hood into the street, bruised but unbroken. This probably explains a lot about me.
User name checks out at least phonetically…. as canopy-sore-ass
Touché
*golf clap*
Parents just did not give a shit back then! Modern parents doing what ours did would be in jail for sure.
Mine told me that they couldn’t figure out the car seat so the nurse suggested that my mother just hold me on the way home from the hospital when i was born
Actually, this is trivially easy. In 71, it went from 57 to 60HP (SAE gross). In 75, it went from 46 to 48 HP (SAE net). So 60 HP gross is equal to 46 HP net. All other things being roughly equal, fuel injection was 62 HP net.
Also, it’s likely the system was K-Jetronic and not L-Jet.
I wish you could edit. That’s 62 HP gross.
I mean, you could have read the article and see I came up with the numbers right in there? Did you think I wouldn’t do the math? And it was L-Jetronic. Look, here’s the manual: https://www.yumpu.com/en/document/read/46097915/vw-l-jetronic-fuel-injection-workshop-manual-pdf
Yes, definitely L-Jetronic for Beetles. A ’77 sedan was my introduction to fuel injection and still holds the distinction of being the only fuel-injected car I’ve owned.
I don’t think you needed to use a percentage of power reduction or if that’s even valid. Parasitic losses were roughly the same between the two. I think you could go with a simple constant offset. Either way you come up with roughly the same answer.
I’m actually pretty impressed they went with L-Jet. According to that manual, they also were using the full implementation of sensors.
Not K-Jet. VW Type 3 and 4 motors had D-Jet, and the Beetles, which got fuel injection a bit later, used L-jet. I’ve still got a fuel injection computer for a ’69 Squareback and I could beat someone to death with it.
I’m sure you could but would it be as satisfying as the simplicity of using a 34 PICT-3 carburetor to do the same job?
34PICT-3 is fine, as long as you’re not trying to use it with a 009 distributor…
Let’s not forget changing emission standards (esp. in CA) that forced retuning of engines to be compliant.
I’d guess the reason VW continued to rate in gross HP was because they never changed the engine from 71-74. US manufacturers changed something every year, hence the need to re-rate them. It looks like VW didn’t. Sure, it would be nice if we could find the gross HP rating of the L-Jet model. Maybe it could be calculated from a rated top speed and the drag coefficient.
I guess it is because they couldn’t rate them insufficient?
Hmm.. my first car, a 1972 VW Squareback .. had fuel injection – believe it was 1600 cc.
And didn’t the vans have fuel injection before 1975?
Why did VW wait several years to put it into the beetle engine ?
Probably for $$$ reasons.
Likely because the system was brand new and unfamiliar. You have to be careful with your bread and butter.
I always thought it was delayed on the bugs because so many fuel-injected Squarebacks caught on fire and burned to the ground; my brother-in-law’s did, and so did a LOT of others.
https://www.bainbridgereview.com/news/classic-vw-catches-fire-at-island-village-shopping-center/
The Type 3 was the more upscale car, for West Germany’s newly resurgent middle class, created by the Wirtschaftswunder, it would make sense that it got the feature well before the Type 1 that VW ideally wanted people to trade up from.
Meeting (or attempts to meet) Emissions requirements was the reason VW went to FI on T1 in 1975…