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Hagerty
Hagerty Employee

5 famous V-8s whose displacements stretched the truth | Hagerty Media

We know that the 1960s were full of horsepower hijinks, but did you know that manufacturers sometimes fibbed about the size of their engines? Indeed, that burbling V-8 in your beloved classic may actually not measure up to its promised displacement. We rooted out five of the worst offenders.
https://www.hagerty.com/media/lists/5-famous-v-8s-whose-displacements-stretched-the-truth/
124 REPLIES 124
Gary_Bechtold
Technician

Are we keeping it just to cubic inches? Ford's famous "5.0" in the 80's and 90's was technically a 4.9L V8. It was not the 305 an actual 5.0 would be. Ford rounded up again even in liters. Rollin' in my 4.9 would have still worked for Vanilla Ice.
Sonic_R
New Driver

I believe Ford christened the Windsor 302 as the 5.0 as they already had the 300 six cylinder truck motor as the 4.9L.. the 5.0 was offered in the trucks and being a V8 it had to be 'bigger' so 5.0 for the V8 and 4.9 for the six cylinder
camarogirl57
Pit Crew

And speaking of the 300ci 6, It was an option on the '70 Mustang. I drove one on a delivery trip when working for a Ford dealer on L.I. That 300ci Mustang was amazingly quick! A great combination.
llawrence9
Intermediate Driver

A 300 6 is heavier than a 302 and I do not believe any six bigger than the 250 was in a mustang, but I would like to be proved wrong.
Autoxr1
Pit Crew

The 300ci I-6 was only available in trucks and never offered in the Mustang.  You are probably thinking of the 250ci I-6 since that was the larger optional engine over the 200ci I-6 base engine in 1970.  The 250 became the base Mustang engine in 1971.

blueox76
Pit Crew

Yes, and some journals even advertised it as a 4.9. But since Ford had already long had the legendary 4.9 I-6 engine, they chose to round up. Does have a nicer ring to it.
OldRoad
Instructor

Ford may have fibbed in CID but they also fibbed about HP numbers to keep the sweat off the insurance companies fore heads for better sales. The 410 for a single and 425 for the dual carbs were actually 485 and 550 HP. for the 427. Actual for the 428 was in the 400 HP range. The tallest tail of all was the 375 HP advertised for the 429 BOSS. that one is close to 500HP.
Sonic_R
New Driver

Ford advertised lower horsepower for the 2003-04 Cobra too.. it was published at 390 hp and would dyno at about that at the rear wheels which would be about 440 at the crank.
WerbyFord
Pit Crew

Hey wondering where you got those horsepower figures!
The 400hp for the 428CJ is about right for the FoMoCo A-Curve method (headers & loose side tolerances). Nominal with ope iron exhaust about 380hp, still way over "advertised".

The 485hp and 550hp for the 427, that sounds more like race trim of some sort? I think the ORIGINAL 427-4v and 8v, with the original smaller 306-306 cam, indeed made just a tick over 410hp and 425hp as advertised. But the cam got bigger, then the medium riser starting in 1965 added more, but ratings never changed.

The 429 Boss at 500hp, never heard that one - any sources?
Mozeby75
New Driver

Then why was the 429 Boss slower than the 71 Boss 351? I’ve seen a few Ford guys claim the Boss 9 made crazy power but there’s no road tests from that period to back it up.
Diego
Detailer

I think the Boss 429 suffers from a poor reputation out of the showroom, but it's not the slug we are made to think it is. Slowest ET by the magazines was 14.09, and I believe the fastest was better than the Boss 351.

And then there's this:

https://www.youtube.com/watch?v=T-PZ7TJXmT0
mpzz
Detailer

The Boss 429 engine was created for NASCAR. They didn't care how it performed for the street, so in detuned street form it was a huge disappointment at the time (yes, I was alive and driving and reading car magazines in 1969). Doesn't mean it wasn't a great engine, but sometimes it's tough to make a racing engine liveable on the street and still perform up to its potential.
Mike_E_V
Detailer

Thanks! That explains why our 66 Mercury Park Lane with the 428-C6-9" posi rear end smokes the tires. No ads back then for the 7 liter Merc. All Fords. The quietest quick Ford or the quickest quiet Ford I believe was one of the catch phrases in 1966 for a 7 liter galaxy.
RokemRonnie
Detailer

My Lotus Elan has badges that read "1600" but the Twin Cam was really 1558cc.
Flashman
Instructor

In the '70s, Suzuki made a motorcycle labelled 350 cc but it was actually 315; a very big difference.
Tinkerah
Technician

I wasn't going to veer into motorcycle engines but since you brought one up: I think because bike model names usually involve the engine size in some form they round to get a smoothing sounding model name. As far as I know, they always round up.
mpzz
Detailer

My '73 Honda CB350 was actually 325cc. Great first road bike for a kid, though.
TrustyRusty
Intermediate Driver

I bought a brand new, 325cc "350" when I got out of the Army in 1968. It was a CB350 and an absolute rocket! I think ir had a redline of 10,600RPM, but I often shifted it at 12 grand. For its day, it was a fast little motorcycle.
JimK58
Pit Crew

I had a 1980 Suzuki GS1100ET with actual displacement of 1075 cc but it made 105 horsepower. In contrast, I also had a 1965 MG Midget Mk II with an 1100 cc engine that was actually 1097 cc (not too much of a rounding up there). But the engine was rated at only 59 horsepower. Was this just the result of 15 years of technology improvements or simply car vs. motorcycle?
Chevydodgefordu
New Driver

The Chevy trucks in early 70s used 400 fender badges when the engine was actually a 402 cubic inch.
zoe85
New Driver

It wasn't just trucks, the 402 found its way under the hood of many SS396 Chevelles and full size Impalas.
greatscott73
Intermediate Driver

The 400 in the trucks was actually a small block, and a different engine from the 396-402 rat motor. The small block was 400.9 cubes.
Mike_E_V
Detailer

We had a 73 Impala convertible and it was a 400 small block. One of the best driving cars we have ever had the pleasure of owning.
Olecarluvr
New Driver

I currently have a '71 400 small block. I've always liked these engines, the torque they make is outstanding, especially in front of a close ratio Muncie.
dooscoop32
Intermediate Driver

Yeah the reason they increased the 396 to 402 was so their smallest big block would be bigger than their biggest small block, which was the 400. This was to avoid confusion and all it did was create more of it.

When you saw a 400 emblem on the fender of a Chevrolet product back then, you had to look under the hood to know which engine it really was.
241Hemi
Pit Crew

I was told GM was stuck with a pile of well seasoned 396 blocks that did not meet spec at 4.09 bore but could be salvaged at 4.125, due to a quality control problem at the foundry. After setting up the line for the 402 they continued building 402 engines after the stock of blocks were used up. The early 402 blocks were supposedly more "stable" than the 396 and later "green" (un-aged) 402s. Not 100% sure this was true, but it was the skuttlebutt back in the early seventies. The 402 didn't seem to suffer as much from flat cams as the small block 400 - which also suffered from a higher than normal incidence of premature oil burning (which IIRC was a valve guide issue)
RAD2ggs
New Driver

You could have gotten either a small or a big block, depending on what options were ordered for a C/K pickup or Blazer.
Tinkerah
Technician

I think I read somewhere a long time ago (making my statement highly suspect) that the big Chevy was actually 396 CI only for its first year but grew to 402 immediately after, but always named "396".
dooscoop32
Intermediate Driver

No the 396 was a 396 for 1965 thru 1969. Then in 1970, they increased the 396 to a 402. They kept the 396 moniker because it was such a famous sounding number. SS 402 just doesn't have that same ring.
WF
New Driver

Porsche's famous 911 flat-six was built in various displacements over the years. The 1972 version, called "2.4 liter"...... measures out to 2341 cc..... or 2.34 liter.
joepalmer
Pit Crew

Yes sir; the Mercedes Benz famed M 100 engine was installed in the W116 chassis in 1975 to create the famed "banker's hot rod", the 6.9. In reality, the displacement was closer to 6.8 but the race car drivers (Lauda et al, dictators, and movie stars who bought the fastest production sedan in the world, shrugged off any discrepancy. With prices of W109 6.3s rocketing up, savvy buyers are scooping up 6.9s; especially preserved low mileage examples.
dreamingeagle
Detailer

this sedan was faster than the 5-series Bimmers of the era and the Saab Turbo?
Ray48
New Driver

You guys do a great magazine, but come on. Do c.i. discrepancies averaging about 1 really deserve a banner headline story? Was there nothing better to write about this week?
Diego
Detailer

How would you improve it?
joepalmer
Pit Crew

The Honda CBX 1000 Supersport (twin shock and Pro-link) were marketed as 1000 cc, six cylinder 24 valve, four cam engines (one liter).. At the time, the fast production motorcycle in the world. A careful measurement reveals the dis[placement as 1047 cc; for a bit of understatement
jdlmodelt
Pit Crew

I thought the combustion chamber displacement was also included in the engine displacement total. not just bore and stroke. If you included the combustion chamber volume space when the piston is at TDC, does that make these numbers correct?
cwfritz
Pit Crew

Engine displacement is the measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers .

 

https://en.wikipedia.org/wiki/Engine_displacement

Berkeley_Zenlea
New Driver

Did you know that if you bought a 1969 SS-396 Chevy you got a 396.9, but if you bought a 1970 SS-396 you got a 402.6? For whatever reason, the bore of the 396, which had been 4.094" since it's introduction in 1965 was changed to 4.125" for 1970 and later. It was still called a 396 in the performance cars but was called a 400 in full sized cars.
Diego
Detailer

It was called a 400 in Chevelles too.
ruzman
New Driver

Mercedes SL55 is a V8 which is actually a 5.4
Altema22
New Driver

It's reasonable that they would adjust the numbers to avoid marketing confusion. It's not just math, as the displacement would often serve as a "name" for many engines. I'd be more concerned about the performance not measuring up, but a lot of these engines gave more power than what was advertised.

see2xu
New Driver

The M156 AMG V8 in my CLS63 displaces 6205 cc, which Mercedes advertised as 6.3L on the cars’ flanks, and in marketing material. Paying homage to the earlier 6.3L V8 that powered the 600SEL favored by tin pot dictators the world over, and the 300SEL 6.3, of the ‘60s and early ‘70s.

The Big Three haven’t been the only ones capable of telling nose-stretchers, over the years.

ed
Detailer

And the newer twin-turbo used in 63 models is actually 5.5L. Mercedes now says the model numbers were never intended to represent engine size. Right.
Slocumotive
New Driver

This one is certainly not a V-8, but the 12A Rotary engine. It was always listed as a 1.1 liter, with 1146 cc. I spent way too much time thinking of this. Is it really a 1.2 liter if you round to one decimal? This has always perplexed me.
Al
Intermediate Driver

As I recall, the Honda 350's of the early 1970's were 325 cc displacement
wtkern
New Driver

Now wait a sec... there's plausible deniability here...

Take that Ford 427, that's supposedly 425.816 cubic inches. Allowing for thermal expansion in bore and stroke, at 6.5 x 10^6 inches per (inch x deg F) and only 180 degrees F above room temperature, that displacement works out to 427.312, rounding by the usual rules to 427. Perhaps they were going on "hot dimensions", which, it could be argued, is MORE truthful than cold dimensions, as most of time you're operating the engine, it's hot. Maybe, you know, maybe THAT's what they were thinkin'.

wtk
TrustyRusty
Intermediate Driver

If you REALLY want to get technical, a worn out engine contains a greater displacement than when it was new, owing to bigger cylinders!
JDull139
Pit Crew

My Morris Minor 1000,is a mere 948 cc's.
JimK58
Pit Crew

Years ago I met someone with a '59 bug-eye (Frog-eye) Austin Healy Sprite Mark I that originally had the same 948 cc engine as your car. But he replaced it with a 1275 cc engine from a Sprite Mark IV and somehow located a fuel injected head setup for it. He used to race it at a track in Lime Rock, CT
He said he regularly buried both the speedometer and tachometer needles while racing!