Transverse layout

For a rear/mid-engined car, have always assumed it was a "size thing." The car can be made shorter or (as in the 3x8) the same size car can have additional space for luggage/whatever). I've also heard it said that transverse is more efficient because the drive doesn't have to be directed 90 degrees to the crankshaft output. But it still has to have gearing to move the centerline of the thrust from the crank to a different location but maybe the gearing is less of a loss than the 90 degree setup? It seems to me that if transverse really was more efficient, it would be used in F1 cars. I ASSUME(!) that Ferrari decided for good, technical reasons that transverse wasn't the way to go forward as far as increasing power/performance was concerned. Hopefully, some engineering experts will weigh in.

 

Going longitudinal, things can be designed and built symmetrically especially the exhaust and, if desired, turbos. Also with no transmission under the engine, the whole package can be lowered for better center of gravity.

 

No need to have the trans under the engine just because it transverse mounted. On advantage of transverse is no torque along the longitudinal axis of the car.

 

There is a bit of this involved as putting the gearbox directly behind a transverse engine leaves no places for the rear bank exhaust manifold and the center-to-center distance from the crankshaft axis to the gearbox input axis gets kind of large. Also, the transverse layout for a longer engine really forces the designer to put the radiator up front (so a negative for the hot coolant tubes passing thru/under the passenger compartment) and puts a hot exhaust manifold against the passenger cabin. Once you make the decision to put the coolant radiators in the (mid-engine) engine compartment per Kcabpilot's point, and are using a V8 or V12 = it makes the longitudinal layout more attractive. I believe the second gen NSX went to a longitudinal layout even with the shorter V6.

 

Rear boot / trunk space an important selling point with the 3x8 series in the 70,s
It’s a nod towards everyday practically compared with the Boxer .
After the 246 owners wanted some where to hang a jacket or Chuck a bag as well is occasionally carry extra passengers hence the GT4 came before the GTB / GTS, which lost the rear seats but kept the rear trunk ,

 

One optimizes mechanical grip, the other gives more options for aero... just a thought


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The Lamborghini Urraco, Silhouette and Jalpa all used transverse V8’s mounted amidships. Lancia Stratos too. I think it is just a question of packaging on a road car. You have the distance between the seats and the axis of the rear wheels in which to fit engine, transmission and differential. A shorter block like a V6 makes life easier but a V8 is a challenge unless you accept a bulge between the seats or a ‘cab forward’ design. Placing the engine transverse coupled with the transmission and differential was a neat solution to the problem. Later they adopted a different approach (starting with the 288 GTO?) by hanging the transmission out behind the differential, passing drive from the engine back to the transmission then forward to the differential. Mondial T followed suit and all V8 models afterward I believe. Lamborghini’s Countach placed the transmission first, between the seats, so drive went forward to the transmission, then backwards through the sump to the differential placed behind and below the engine.

 

Mike,

Honda tried the transverse engine in Formula One, in one single car only (so not as a principle) and for a short period of time, in the sixties. It was not a success, but admittedly, Honda tended to overcomplicate things just for the pleasure of toying with it...

Rgds

 

https://www.ferrarichat.com/forum/threads/3-4l-engine-dyno-results.377386/page-2

Per the thread above, some others have dyno'ed engines and show up to a 22% loss which @smg2 pointed out is a larger loss. In a basic search, the goal is around 15%. It would be interesting to see what that is compared to the 348 or mondial-t as the cars went transverse.

It would also be interesting to compare to other cars in the world with different layouts. I always hear Porsche 911's are strong in this area (don't kill me).

 

I don’t think the Lamborghini V12 would fit between the rear wheel axis and the front seats if mounted longitudinally. It is too long. To fit the engine longitudinally would have required a complete restyle of the car. I have read the engineering inspiration for the layout came from the clever Issigonis packaging applied in the Mini. The profiles of the Miura and Countach show the difference.


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That is an interesting observation about exhaust routing. An advantage of the flat plane crank is the evenly spaced exhaust pulses which improves flow. Companies such as BMW discretely (from the general car-buying public) convert their V8s to flat planes in their factory race cars.

Since the 3x8 is basically two 4-cylinder engines joined together, probably the effect of the asymmetrical exhausts can be mitigated through design.

Below is a photo I took this evening of my engine (I am taking stuff apart right now). The engine looks about as wide as it does long. However, with the transverse configuration, the gearbox can be stacked transversely with the engine keeping the package compact. In contrast, a longitudinal engine requires that the transmission extend also longitudinally from the back (or front, in the case of the Countach) making it a much longer package. The wheel base might need to be longer, there would be no room for a trunk, etc., a la 288 GTO.

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^ yeah that cutaway shows the huge bulk of the V12 drivetrain. The Countach really is mostly engine. Was lucky enough to get a ride in an LP400 some years back. One of those “don’t ever meet your hero” experiences.

 

there are more transverse mid-engine cars with transaxle mounted conventionally at the end of the motor.

the boxer - testarossa are longitude drivetrains sitting on top of the gearbox as well to shorten the drivetrain. still they dont have trunk in the rear.

there are longitude conventional drivetrains with aft mounted transaxles with trunks. bmw M1, europa, esprit, pantera, Ligier JS2 just to name a few... some have more storage volume than the 308


i agree with the advantages that the plan view footprint is smaller which ads in packaging. the disadvantage with the motor sitting on top of the gearbox is the higher location of the motor which is huge detriment to the CG. everything is a compromise...

 

It would also seem that weight distribution would also be factored in. Polar moment? Ex: Porche engine in the rear vs 308 engine in front of rear wheels. Ever spin out in a Porche?

 

i had a couple of 308s, 930 and i kept the 911. what do you think the weight distribution on a 911 is vs a 308? i dont have the cross wheel weights of my car handy but a quick search shows autotest mag listed and early vetro gtb at 41f- 59r% road and track got a 2.7 911 at 43f-46r% rear. typically a n/a vintage 911 is only 1 or 2 percent more reward which is easily offset with fuel weight since the tank is further up front. of course 911s the weight distribution varies and can get worse depending on the year and model especially on the 930s. with driver weight and fuel it affects the static weight distribution more than the 308.

never spun a 911 but ive spun plenty of other front engine cars on the track. with the low flat motor and if you keep your foot in it, the rear end is planted like no other car. 930 had the worse weight distribution. despite that its unfavorable rear weight bias its a heavy understeering pig no matter whats been written about it. you can loose the rear end if you lift in mid corner or trail brake too much to the unsuspecting driver.

 

Interesting numbers but different here:
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It is a well known fact that "Polar moment of inertia" was a theory very much in favor at Ferrari during the sixties and the seventies. In Formula One, that great genius Mauro Forghieri considered that he achieved eventually its potential with the Ferrari 312 T in 1975, which had all the four radiators (water and oil) "inside" the wheelbase (many Formula One cars still had water radiators in front of the front wheels, and/or oil radiators behind the rear wheels, and a transverse gearbox (the "T" meaning "trasversale") to avoid the overhang of the gearbox casing, shaft, pinions, etc...behind the rear axle.
That "Polar moment of inertia" theory was very much applied to road cars also, and reached its theoretical potential when the transverse gearbox introduced in Formula One in 1975 was fitted to the Ferrari 348, which also dispensed with the water radiator overhanging the front axle.

Rgds

 

^ just like my Lotus Europa!

 

well the 997 isnt a 308 contemporary aircooled G body. 930 at a dismal 38 -62 split too...you can drift them seemingly forever with ludicrous long gear ratios once you get them rotated. awful blunt handling car in stock form from the excessive understeer and lag.

911s are much better than 930s. they do have very low polar moment its just that the CG is concentrated too far in the rear.... at least the the CG is placed low.

alfa gtv6 high polar moment with rear mounted transaxle, like 944T, vettes, GTR... a favorite for hardcore track junkies. ive driven all of these fine handling street cars though wasnt comfortable in a 944.

imo 348,355 with the T drive which ive driven tend to be twitchy... some say they arent so forgiving i tend to agree. i find the more traditional layout newer 360 and 430 are much better handling cars. have yet to try a dino

 

the 308 - 328 series on track can be a slight hand full when you are really pushing it... better if you have it set up for track work with more camber and a bit of toe... but still the engine being mounted higher is the culprit - compared to other cars. once you get the back out ... you have to be really fast to keep it going ... however in the 288 GTO with a longitudinal set up .. .it corners much nicer and is not as "snappy" ... unless you are building boost at the same time... once you hit 3800 RPM you want to be pointing strait ahead..... I have seen some really good drivers eat up 360's and 430's in a track prepped 308... with about 280 - 300 HP... slightly lighter.... but you are working at it big time.