Flat Crank's

I'm sorry they did not abandon that, what I meant is that it is no longer at regular intervals.

 

Yes the boxer had a 120 crank for the same reasons I described earlier.

The only Ferrari 12 I am aware of that had a crank design with the pistons on opposite banks being in the same position was during Niki Laudas time in F1. He referred to them in his book and referred to them as flat 12 and V12 meaning your pure boxer style verses a 120 degree crank. The flat 12 as they called it internally gave a different torque / horsepower curve that was more suitable for some of the tracks.

 

No problem Brian -- all is clear.

Like you said, each bank is still working like a proper in-line 6 with the evenly-spaced exhaust pulses going into their respective collectors so fudging the bank angle is more of a minor acoustic sin (rather than a functional sin). It's interesting to note that they fudged the other way on the 206/246 engines going up to 65 deg.

Still looking for a shot of a 60 deg V-12 engine crankshaft (I'm wondering if the counterweighting is less than on the TR crankshaft) -- no one has one!?

 

A true boxer engine would weight more than a Flat-12 (180 degree V12) due to extra connecting rods and other components, correct? Also, in the older days, in order to solve the vibration problem in the "flat" engine, it was necessary to have it designed as a true boxer configuration, but as the automotive technology progresses, balance issue is solved and thus the birth of current day flat-12 engines. Is this also correct as well?

 

They look very similar. A little less counterweighting, lighter recip components, always trying to find a way to make it lighter.

Have you seen a recent F1 crank? Whoooweee can you say minimalisim?

 

This is very educational and opens up another question regarding firing and degrees of crank revolution. It all makes sense except if I remember correctly the Renault's V10 engine in F1 was a 110 degree V at least up until a couple of years ago. I don't remember if it was the same last year...How did they get around the equation above?

 

The same way the 55 deg bank angle works OKish on the V-12. On Renault's V-10, each bank will be a proper in-line 5 cylinder with exhaust pulses arriving evenly-spaced into their respective exhaust collector (every 144 deg of crankshaft rotation), but the relationship between the two banks will not be "symmetric" (i.e., it will not be 72 deg of crankshaft rotation). The equations must be adhered to only if you want the time difference between the two banks to be exactly 1/2 the time between exhaust pulses arriving in one of the collectors, and, since the exhaust systems on each bank are (fully or quasi) independent of each other, the relationship between the two banks isn't critical for performance -- it just sounds better when the equations are met.

 

I think in Renault's case, they wanted to take advantage of the low center of gravity thus improve handling of the car as a whole with the high angle V10 engine. But I think they were having weight issues, reliability issues and the engine is simply under-power. So perhaps, they never did get around the equation.

 

Apparently, the 288 GTO and the F40 used 90-degree V8s... why?

http://www.ferrariusa.com/GTCars/PastModels.asp?content=PastModels

 

Thanks guys - very interesting, always nice to be educated more. So I assume that historic 911s and Boxsters etc have the same situation of not being a true "boxer" but perhaps the 356 was?

 

dan360 -- Most (I think) Porsche and the (classic) VW flat engines have the right piston motion for the "true/original" boxer definition, but no commonly-available modern engine (that I'm aware of) fires the power stroke of two cylinders simultaneously (so that's why you can conclude that the 356 isn't a true boxer either).

Dave -- Can you rephrase the question? All of the F V8 models use 90 deg V8 engine blocks -- are you saying that 288GTO and F40 are reported to use 90 deg crankshafts?

 

The crank is exactly the same design as all other (up to) current Ferrari V8's.

 

Steve,

Sorry, I was confused... yes, I did mean to say that the 288GTO and the F40 have 90-degree crankshafts... but I realize now that I was incorrect because I misunderstood what I was reading!

 

I guess I have never heard of a flat engine ever being called anything other than a boxer engine, that its shape just simply resembled a box. Also, I have never heard of engines with cyliders firing simultaneously, always one after another. In a Harley, the rear fires first, followed by the forward, but at different time intervals of 360 + 60 and 360 - 60. But I am trying to recall the Porsche 908? some motor that was a flat 8, but had some weird crank and vibrated so bad it destroyed anything bolted to it. I think someone figured out the generator was being subjected to 120G's of vibration, if my memory serves.

 

The crank configuration I was trying to describe in post 27 did not have 2 cyls firing at same time. To make it simple I will use a 2 cyl opposed motor as a example. It has 2 pistons at TDC, one firing, one at ex/in crossover (overlap). Both have individual, conventional pistons and rods, but both are on seperate throws of the crank. It makes for a much more elaborate crank but as I said earlier Niki Lauda said it made a power/torque curve that they found preferable for some tracks. That was the motor that internally during that period on the F1 team they called the flat motor while the more normal configured motor even though it was horizontally opposed was referred to as a "V".

 

PICS OF A TR CRANK COMING RIGHT UP



SOME VERY IMPRESSIVE INFORMATION GENTLEMEN I MUST SAY

 

sorry i thought i could send my pic of a daytona crank crank to compare but remebered its in a faulty harddrive

but why would they be different anyway?

 

Steve, I don't have my camera at work with me but that looks exactly like the 330 crank that is about 30 feet from me. The only exception is that unlike the TR crank shown the 330 has a short, splined snout.

 

i have a factory piston disposition diagram for a 365bb if anyone can teach me how to save a pic from a pdf file

 

Thanks for the pics and descriptions, but I'd still like to see a Columbo V-12 crankshaft if possible -- so keep that open.

On the TR, it seems like they went overboard trying to minimize the NVH (and on 348s, doing that 2-piece flywheel thing, they truly lost their minds ), so I was wondering if they used less counterweighting on early V-12s (and accepted other compromises) to keep the overall inertia down.

They might be "scaled" in the same shape, but the TR crankshaft has got to be bigger/longer/stouter than the Columbo crankshafts.

Paul -- I tried to find the (on-line) article on the early BMW boxer engine I was referencing for the simultaneous power-stroke firing, but can't now (it even had an animation of the internals of a working engine). After reading up some more on the modern air-cooled BMW 2-cyls, they definitely fire the power stroke on alternate revolutions, but have a wasted spark system so both cylinders "fire" their spark plug simultaneously (and every revolution). I'm now thinking that either the Author or I misconstrued the meaning of "firing" so I'm unsure about the whole thing. But I do agree with your observation that in the last 50 years anything "flat" has been called a "boxer" (regardless of what's going on inside).

 

Sizes are very similar, bearing sizes are the same I believe since the late 212's or early 250's. Internal parts look almost identical, rods change some in length and pistons in bore size vary some. Until titanium rods came out you were hard pressed to tell the difference in lower end parts between a lot of the motors. When I believe the 330's came out everything had to get a little longer due to bore spacing but you can see why Ferrari motors got such a reputation for strength. Parts that were designed for 3.0 L 200 whatever HP were almost unchanged until 400 HP V8'S and 450 HP 12's. In fact on the 575 they have abandoned the titanium rods and gone back to the old steel one's due to the fact as they told us that the titanium rods had reached the limit of their strength on the 550.

 

For some reason I will never understand, every book I have ever read call every "flat" engine thats 180 degrees opposed, a V engine. And I think that goes all the way back to the earliest motorcycle and aircraft engines. Maybe they just had to use a letter to describe the layout in order to get a patent? Are there engineering datums that need a specific letter to signify opposite directions? Maybe no other letter can lay out flat like a V?