Can someone explain F1 N.A. engines?

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
DiogoBrand
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Can someone explain F1 N.A. engines?

Post by DiogoBrand » Wed Feb 28, 2018 3:55 am

So from what I know, F1 N.A. engines have for a long time been engines with short strokes, big bores, relatively low torque and RPM as high as possible.

So I know that for the same amount of torque, higher RPM equals higher power, and I guess shorter strokes work better at higher RPM, but apart from that I'd like to know why they did things like they did:
Pretty much no other racing series that I know of have engines like that, so why did they do things like that in F1?

What would be the downsides of an engine with longer strokes and narrower bores? Couldn't they achieve the same power with more torque and lower revs? (All of that with N.A. engines).

wuzak
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Re: Can someone explain F1 N.A. engines?

Post by wuzak » Wed Feb 28, 2018 4:21 am

Limitation of capacity.

As they were restricted to 3.5l (1989 - 1994), 3l (1995-2005) and 2.4l (2006-2013) and weren't allowed supercharging, rpm was they way to get more air through the engine, thus enabling more fuel to be burned and more power to be produced. Also, were restricted to a maximum of 12 cylinders to 2000, then 10 was mandated from 2001-2005 and 8 from 2006 to 2013.

Short strokes reduced the piston speeds and accelerations, at the cost of a heavier piston. It also allowed larger valve area to be used, which allows more air through the engine as well.

When the V8s were introduced the bore size was mandated at 98mm, which gave a stroke around 40mm.

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Re: Can someone explain F1 N.A. engines?

Post by DiogoBrand » Wed Feb 28, 2018 4:31 am

Couldn't have explained it any better. Thank you!

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Re: Can someone explain F1 N.A. engines?

Post by MrPotatoHead » Wed Feb 28, 2018 5:59 am

Here's a good read that compares F1 to NASCAR engines:

http://www.epi-eng.com/piston_engine_te ... _to_f1.htm

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Re: Can someone explain F1 N.A. engines?

Post by J.A.W. » Wed Feb 28, 2018 6:23 am

wuzak wrote:
Wed Feb 28, 2018 4:21 am
Limitation of capacity...
Or, limitation to 4-strokes, which must run super-high ( & super-expensive) rpm,
- to get any useful work done on 'pump gas'..

(G.P. motorcycle engines were 2T, & making ~440hp/Ltr @ 13,500rpm N/A in this same period).
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"Yes.. spare us your ridiculous remarks, you insensitive idiot!"

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Re: Can someone explain F1 N.A. engines?

Post by Tim.Wright » Wed Feb 28, 2018 7:19 am

Another partial reason for the short stoke is to reduce the GC height of the engine. The shorter the stroke the shorter your crank throws need to be and this effectively sets your crank height in the car.
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Tommy Cookers
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Re: Can someone explain F1 N.A. engines?

Post by Tommy Cookers » Wed Feb 28, 2018 11:20 am

the OP has suggested short stroke high rpm NA engines had relatively low torque and this would be better with longer stroke
they didn't and it wouldn't
when the engine didn't/doesn't have to do the gearboxes job

pneumatic valve springs are rightly seen as an enabler of extremely high bore:stroke ratios
but eg 7 speed instant shift gearboxes and 'drive by wire' digital management of throttles are also vital

higher B:S ratios not only help mechanically to allow higher rpm but also allow a bigger valve area relative to any rpm


'our' F1 really began 50 years ago with the Cosworth DFV becoming widely available
it's B:S ratio was quite low as the bore centres were taken from the UK Ford 1 litre 1958 road car
I wonder what Mr Duckworth would have used if there had been a free choice ?

the BRM and Weslake V12s had even lower B:S ratios (being derived from stroking the BRM 1.5 litre V8)
Beltoise's wet 1973 ? Monaco GP win implied this gave a very driveable powerband
Last edited by Tommy Cookers on Fri Mar 02, 2018 12:13 pm, edited 3 times in total.

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Re: Can someone explain F1 N.A. engines?

Post by Jolle » Wed Feb 28, 2018 11:42 am

DiogoBrand wrote:
Wed Feb 28, 2018 3:55 am
So from what I know, F1 N.A. engines have for a long time been engines with short strokes, big bores, relatively low torque and RPM as high as possible.

So I know that for the same amount of torque, higher RPM equals higher power, and I guess shorter strokes work better at higher RPM, but apart from that I'd like to know why they did things like they did:
Pretty much no other racing series that I know of have engines like that, so why did they do things like that in F1?

What would be the downsides of an engine with longer strokes and narrower bores? Couldn't they achieve the same power with more torque and lower revs? (All of that with N.A. engines).
Torque and power are connected. Basically, power is torque x revolutions/time. So if you want to have more power, you need more torque or more rpm. In NA engines, this is done with more rpm (if the capacity is restricted) or with a greater capacity (the cheap options). That high revving engines have a big bore and a very short stroke has to do with the piston speed. The max piston speed (at the moment) is around 10.000 ft/s. So, if you want more revs you need to make travel of the piston as small as possible.
As time and engineering possibilities develop, F1 was going into extremes (as always) and they mandated a minimal bore to keep the stroke a bit normal (and affordable). A while back I saw some KTM pistons that looks more like plates then pistons... really amazing what they can do these days. As a final restriction they limited the amount of revs, basically levelling all engines to the same power.

With turbocharged engines this all is very different. Revs are not important because they are not the source of the amount of air going trough the engine. More air is more power because you can put in more fuel. It's all about boost pressure. Of course, in the case of efficiency there are sweet spots with capacity and revs, but in theory they don't matter. Its about how much fuel (energy) you can burn.

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Re: Can someone explain F1 N.A. engines?

Post by Tommy Cookers » Wed Feb 28, 2018 12:13 pm

piston speed is never the issue - it's not a hard limit to rpm
piston etc acceleration is a hard limit to rpm as the strength requirement increases with the square of rpm
fundamentally rpm is proportional to the square root of the B:S ratio

the boosted SI engine has in principle a choice of low boost/high rpm/high CR or high boost/lower rpm/lower CR
the turbocharged engine still throws away power
compounding is a seperate factor - and of course NA compounding is possible

FightingHellPhish
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Re: Can someone explain F1 N.A. engines?

Post by FightingHellPhish » Thu Mar 15, 2018 4:31 am

can do some fun things with N/A like manipulating the scavenging effect with cam specs to produce a positive pressure in the intake. ProStock engines have seen upwards of 3 psi.

Tommy Cookers
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Re: Can someone explain F1 N.A. engines?

Post by Tommy Cookers » Thu Mar 15, 2018 12:31 pm

well yes
but this can be done with boosted engines to get 'free supercharging' of the same % benefit as NA's
eg F1 has 6 tuned length tracts working from a plenum of pressure-boosted air
and the ram effect from the vehicle speed applies equally to both engine types

true the boosted engine tuned-length exhausting to atmosphere won't get near the % exhaust benefit that NA can
but it may be close if it gets tuned-length exhaust action where joining the boost-pressure exhaust upstream of the turbine

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Re: Can someone explain F1 N.A. engines?

Post by godlameroso » Thu Mar 15, 2018 1:41 pm

Tim.Wright wrote:
Wed Feb 28, 2018 7:19 am
Another partial reason for the short stoke is to reduce the GC height of the engine. The shorter the stroke the shorter your crank throws need to be and this effectively sets your crank height in the car.
Taking it even further ultra short crank throws and long rods(within reason) at say, 2.4:1 ratio, gives you long dwell times and higher engine speeds.
The height of cultivation is really nothing special. It is merely simplicity; the ability to express the utmost with the minimum. Mr.Lee

Tommy Cookers
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Re: Can someone explain F1 N.A. engines?

Post by Tommy Cookers » Fri Mar 16, 2018 1:10 pm

ok but ....
a 'long rod' (high rod ratio) gives more 'dwell' close to TDC but of course less 'dwell' close to midstroke

high rpm engines tend to have a problem with combustion speed not keeping ahead of piston motion
so a 'short rod' (low rod ratio) can give more power and design has been correspondingly influenced

ok the very large NA bore:stroke maybe meant the mechanical disadvantages of rod angularity were excessive with 'short rods'
and tests showed rich mixtures helping combustion 'speed' (consistency really) at very high rpm

lawnmower
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Re: Can someone explain F1 N.A. engines?

Post by lawnmower » Wed Jun 06, 2018 6:03 pm

I think that the difficulty of preventing high-rpm rotations of engines is the combustion efficiency. not piston and rod's mechanical strength

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Re: Can someone explain F1 N.A. engines?

Post by gruntguru » Thu Jun 07, 2018 12:24 am

Small cylinders also get the burn done in a shorter time.
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