three liter dyno comparisons/ Ferrari fudging power claims

OK, I know well that is is quite inaccurate to compare rear wheel dyno numbers - but if used as an approximate WAG it does make for fun Pub conversation. In the Maserati section, lvferraripilot posted a very intersting thread which read:

I responded with some collected info on other contemporary 3 liter engines:

Thanks to FChat and others, there is a lot of dyno info out there for casual inaccurate conversation, but it is certainly suggestive Ferrari did fudge a bit on claimed output on probably many of its engines. We all kind of know this and go wink wink nudge nudge, and it is interesting to have a rough idea of just how much....

 

I`ve owned a maserati merak ss and I would say they produce around 50 hp less than my 308 carb car. I also owned a 1972 bmw 3.0 csl and the csl could out drag the merak all the way. The 308 is faster than both and would think they are around 260 bhp. The merak is no way quicker than the 308.

marc
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Until someone can duplicate the machine and test conditions at the factory in the 1970s, and show different numbers, it is pure speculation to say Ferrari fudged the numbers.

 

Exactly right - different dynos yield different numbers; the same engine/car can yield different numbers on different dynos on the same day. Heck, the same car/engine can yield different numbers on the SAME dyno from day to day.

 

This is true. Basically this all comes down to a couple of things:
1. Engine horsepower is not a consistantly exacting figure on any engine. Many factors can affect the "actual" horsepower generated by any given engine, on any given dyo, on any given run. Engine dynomometers are simply pieces of equipment like any other, and are subject to design, wear, and calibration inconsistancies like any other.
2. I think its interesting that when talking about performance tuning, most agree that even as much as 10 hp gained (or lost) is hardly consistantly noticable either from a seat of the pants or numbers perspective, yet a 10 to 20 hp variance in stated hp is somehow the gospel written in stone?

Finally, in the base comparo of the Maser Merak and 308... most contemporary and historical figures place the Merak's performance numbers clearly behind the 308, regardless of hp.

 

We found, in my days of engine building, that it takes a 30HP increase in a 3000lb car to make it a measureably and consistently faster in the hands of an average "good" (non-professional) driver. We also found that anytime a car was louder, it was always initially PERCEIVED as faster, even when the dyno or track tests showed that it wasn't. The classic, "Revs much better," was a common comment.

 

The only 308QV I have seen dyno'd was a Euro version and it was in very decent shape. Definitely not a newly rebuilt engine, but very servicable still. It yielded 188rwbhp which is great IMO.

As for the Urraco, I have only heard anecdotal evidence about those engines being dyno tested and nothing concrete. Would love to hear about their figures at the time.

Being a former Porsche owner and fanatic turned Ferrari fanatic (sorry Pelican Porsche guys), I know that Porsche quoted their bhp figures as a minimum number rather than a maximum or median number. My stock '86 911 Carrera yielded 199rwbhp which was more than factory claims. The engine had 90k miles on it so I can only imagine that new figures were possibly 8-10bhp more than what I had tested. Funny thing is, my '76 308gtb feels much faster than my 911 all day long even though it isn't.

I owned a Merak SS for a while and kept the engine stock most of the time I had it. I had driven 308QVs before getting into the Merak SS, but the power delivery between the two cars was incredibly different. The Merak engine was tuned to be more of a 'stump puller' in that it had a considerable amount of torque available much lower than that of a 308 engine. There was definitely more neck snapping going on, but I could feel the power cut off right around 6300rpm. The Ferrari power started at a bit higher rpm and pulled smoother to a higher operable rev range. The difference was the Ferrari felt like it would rev forever because the power didn't just fall off a cliff as in the Merak. The Merak SS definitely felt faster and is faster because of the torque. I wish I still had one I could stick on the dyno so I can settle this inner battle I have going here. I find it impossible to compare the two engines to my current GTB because of how different they all are. Both engines tuned to Euro spec feel very quick but for different reasons.

The Merak SS tested top speed of 153mph at the Nardi test track which was higher than what the 308 could pull at that track which convinces me that a Merak SS is indeed faster. I cannot give too much weight to any magazine testing done in the day due to a number of different reasons. The biggest being: who is driving the cars and do they really know how to drive these type of cars. the other being, how well tuned are the engines? We all remember that God awful R&T 308GTB article showing a 9 second 0-60 time or something along those lines, and that was a '76 car!

Perhaps someone on the forum has a Merak ss they will dyno test for historical purposes ?


For those of you who have never heard this strange little 90 degree Maserati V6, there was a great video made showing a bench running of this engine as well as tips prior to starting a freshly rebuilt engine (it is mostly informative tech tips but wait to the end). The revving sound at the very end of the video is quite impressive! Undoubtedly a close second place sound-wise to a Dino V6. http://www.youtube.com/watch?v=XDWkx-XNpHc

 

And it shouldnt be that way. I beleive the issue is not only different dyno's, but also the way HP is being calculated. Depending on what book you read (or what web site) there seem to be many varieties of math formulas used to calculate HP. And then the question becomes, are we using HP, BHP, BMHP or BMEHP. While car manufacturers and the basic automotive field at large have no rules to follow, the aeronautical field does and they all stick to the same formulas.

The general math process use's torque and calculates it into HP through a formula, so depending on what formula your using your numbers can be all over the place. In addition, the machine's being used to measure torque could have different power losses and give varying torque figures. In the 308 GT4 service manual, in the section on running in the engine follwing assembly, it speaks as to the amount of torque to apply (load) to achieve a specific HP output at a particular rpm. Those figures should be able to be resolved into the proper formula, and that if we can pull a torque figure out of the engine we should be able to calculate HP using the same factors Ferrari was using. The trick then, would be to apply torque loads in as closely the same manner as they were read at the factory.

Regardless of anything else, the torque being applied to our cars chassis should be about the same from day to day, provided the same application of power, atmospheric environment, fuel quality and engine tuning settings exist. Yet the differences being seen on many of these dyno's seem to be offering swings in measured percentage that are outside acceptable limits. In other words, 300 Horsepower should always be 300 HP. I always found it interesting that any common airplane can be brought up to full power against the propellor and will pull to about the same rpm, indicating the same virtual power was being produced and temperture and climate conditions make very little difference. The same should apply to any engine.

 

While I cannot ever claim to have experienced it first hand, the increase from 65 HP to 85 HP in a small airplane has always been observed as "incredible". I dont think its the physical number so much as the percentage that would be more or less notable. Adding 10 HP to a 10 HP engine (100% increase) would be like adding a stick of dynomite, where adding 10 HP to a 300 HP engine (3% increase) would be more or less unnoticeable.

 

Ok so I just reviewed bhp figures with a Citroen SM expert who has tested dozens of these engines (PM me for info if you want). The factory figures Maserati quoted for the V6 engines has been either dead-on or on the low side to what they are actually yielding at the flywheel. So if a Euro Merak SS engine is quoted at 220bhp, the engine is putting out 220bhp+ at the flywheel.

 

This of course is absolutely correct. However, this discussion definitely is related to the latter example, not 50 to 100% differences.

 

The only way to determine these things between 2 different cars is to put them on the same dyno, with the same athmospheric circumstances, temperature being important mainly.

Dyno figures can be manipulated rather easily, and one machine isn't the other.

Then there is the operator.

As far as factory outputs go, there are also many variables, which is why there are various types of HP: BHP, DIN, SAE etc. The main differences are that test engines are run with or without anxilliaries, airfilter etc.

HP of whichever kind is an exact science, a measurable power output, which may be compared between engines, but you have to test according to the same parameters in order to obtain comparable results.

 

Who cares anyway. In their time the power of these cars was significant compared to the mainstream cars but we're talking about classic cars now that have been surpased in almost every way even by mainstream cars today. And maximum BHP is only one factor of the total driving experience and engine characteristics (what about torque and how the curve goes?)

Just my 2 eurocents.

Best, Peter

 

Peter,

That is of course true, but the chassis feels like it could handle so much more than what the engine gives. And yes, modern cars perform great, but the 308 still handles itself pretty well against most of them.

 

I would definitely agree with this. A perfect example of this being how my 308 actually feels faster than my Audi, in spite of the fact that my Audi has slightly better numbers. The Audi's engine, in spite of being a great and well engineered engine, just doesnt feel as willing as the Ferrari. Its always difficult to explain to people when they ask about the 308, "Wow, it must really be fast", and I have to try to explain that, "Well, No, it really isnt (in a straight line at least). However, it feels fast all around, and handles that speed well.

 

Re claimed HP from the factory...

I was hunting through the web, trying to find some 1/4 mile trap speeds for a 328. I found some ETs but no trap speeds listed. Trap speeds would be a lot more accurate BUT I found a 328 with a 14.2 ET. Figuring the car weighs 3200lbs with the driver - that's a GUESS on my part - that translates to around 205-210HP at the rear wheels which then seems to be pretty much at the factory claimed 260HP at the flywheel for a US car, figuring a 18-20% power loss in the drivetrain. The trap speed would make for a more reliable calculation because it is not predicated on the launch of the car as is the ET. Trap speeds don't change much regardless of how bad the launch and are the best way to really tell if a car is making more or less power after an engine mod. It's much better than a dyno because it's REAL, as in running down the road but obviously it takes a lot more time and is not practical as a normal day to day process.

 

i have owned a 79 merak ss and a 83 gtb qv. the qv felt faster but the merak was not too far off if kept in the rev range. the merak ss sure was sexy though!!!!!!

 

While one would think this should work, once again it depends on how they do the math and how they understand it. I have a few books and have read others on ballistics. I have another book I cannot seem to find anymore (stuffed in a box I guess?) on building a model helicopter from scratch. The reason I bring this up is because in aerodynamics they use the term "square of speed". Basically, any doubling of speed requires a quadrupling of power.

The factor is quite well known in the aeronautics field, but in the automotive field there seems to be a great deal of math errors. The greatest being that some believe doubling of speed requires 16 times the power. This is most pronounced, in my opinion, in Top Fuel drag racing. These cars have not changed a great deal in almost 40 years except in the area of aerodynamics. They are still nitro methane burning 500 cubic inch engines, and they still have a 12 gallon fuel tank, same as they always had. Yet where yesterday they made 2500 HP and topped 250 mph in the 1/4, they now would like us to believe they make 8000 HP. All while burning the same fuel, at almost the same rate per second. ie; the tanks just as empty after a run today as it was 30 years ago. If the motor was making 4 times the power, it would (not should) require 4 times the fuel.

The difference that I see, is that aerospace is guided by an organization that uses imperial rules that arent open to discussion, and automotive engneering has no rules. If an aircraft engine manufacturer claims their engine produces 150 HP, that rating is backed up with agreed upon science. If an automotive manufacturer claims their engine makes 300 HP, there is hardly any science at all, and no rules in place to support it. And the fact that any Tom, Dick or Harry can build a dynomometer and sell them freely to the public at large, without any certificate of compliance or that it meets any standard we all agree upon, or otherwise, totally clouds the issue.

I guess what I am saying is whether we use trap speed, an engine dyno, or a chassis dyno, and unless everyone accepts the same physical laws and uses the same formulas, there isnt any result anyone can claim that carries any weight. Just a quick Google seach for HP calculation brings up half a dozen different formulas, that all would give different answers, and half do not even us gravity as a factor. We need to pick one and everyone agree to it, right or wrong.

 

I sort of agree but I spent many years working on engines where we correlated dragstrip results and the formulas that are now commonly available for predicting ET/trap speed/HP are well worked out. You are right, of course, that as the speed goes up, aerodynamics becomes a big factor BUT, the aero factor is part of what really happens to the car; the dyno is useless for this. In other words, the dyno can tell you what an engine is doing SITTING STILL but it can't really tell you what the car/engine is going to do. As an example of this "synergy," or lack of it, I have a test we did a few years back that shows a 340 Mopar engine in a 1971 Barracuda that produced 320 RWHP on the dyno without the air filter. On the track, the car produced numbers that indicated around 300 HP at the rear wheels (weight/trap speed). Where did this 20HP go? We put the air filter back on the engine, the power and trap speed went up. We discovered that as the vehicle speed went up, the airflow to the carburetor was disrupted by the movement of the car through the air. Putting the filter on smoothed out the flow and the power came back. We also found that "ram air," without a properly designed airbox to ensure there was no turbulence at the carb intake, also slowed cars down.

My point re this is that although dynos are wonderful, and we used them every day, it is what the car actually does on the street/track that matters. I always preferred track testing to dyno testing but, as noted, it takes too long to be practical at all so it was relatively rare to actually make mods and test each one at the track though we did it on occasion. As I used to tell the guys at who preferred doing EVERYTHING on a dyno, "Nobody ever won a race by showing a copy of a dyno sheet!"

 

Good post - as a lifelong NHRA fan, I always thought the "8000 HP" claim was a bit of marketing.

 

Well, some hold it to be outright Gospel, and will argue fuzzy math to back it up. I cant argue except to ask why they arent then running much larger fuel tanks. Maybe they figured out how to quadruple engine power output without burning more fuel? Sure wish I could figure that out for the junk I drive.

You wait and see, in the next few years they will claim 10,000 plus.

 

I had a lengthy conversation with David Hume of Excelsior motor this morning. David was a Maserati engine builder in 1980 when Maserati was still importing based out of Baltimore. He rebuilt engines under warranty or if the car arrived and needed engine work etc. He is still a renowned Maserati v6 expert and primarily works on Citroen SM's now.

David advised me that when Maserati was developing the V6 engine which was ultimately used in the Merak, it was not for the Merak but rather for the Citroen SM. Citroen being a larger company with volume in mind, they required Maserati to be more 'straight' with their bhp claims. Each engine was indeed bench tested, but every 4 or 5 engines went to the dyno for testing to make sure power claims were still in line and obviously to keep consistency. Nowadays it is my understanding that every Ferrari/Maserati/Lambo engine goes to the dyno before installation rather than just bench break-in alone as it was in the day. When the decision was made to put the engine into a Maserati, the engine was massaged a bit with cams and porting, but not much until the SS variant came along which was of course when changes were far more radical.

Interesting stuff. Citroen kept Maser honest in the day lol.

 

I have posted this engine on here before, but I thought this thread is worthy enough to show it again. Sort of the crown jewel of Merak V6 racing engines. 3L 4 valve heads. gear driven crank to intermediate shaft with chains ultmately driving the cams. over 400bhp at 10,000rpm. This engine raced with success with the Ligier team at lemans placing 17th overall and winning its class one year (I believe 1974) against Porsche turbos.

photo courtest of W Bauemer
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hat is one very sweet looking engine.

 

It is indeed a monster of an engine for just 3L. I believe that is the last Maserati engine to compete at Lemans. Impressive that it finished so well and ahead of Porsche turbos, but I was told by someone with the former Ligier team that the engine ran incredibly hot. 10,000rpm does that I guess.