Engines discussion

[ewanc0]

I was having a think tonight (i know, i know)
Why do/did Volvo make 10 valve AND 20 valve engines
AND
Why do/did they make 4 cylinder and 5 cylinder engines

I would think that making variations of the same basic block would be more cost effective, so why would they make so many different engines?

Discuss...........

[stephend]

I don't know about 4 vs. 5 cylinder, but I guess nearly everything switched from 2 valves to 4 valves per cylinder in about '92, when the emissions regulations changed, i.e. at the same time that everything got fuel injection, full engine management and a closed-loop catalytic converter.

[galloot633]

Id love to know where 5 cylinder thinking comes from , usually designers trying to get the advantages from engines with one less and one more cylinders, the 3 cylinder engine is a good example of this, I always prefered the low down grunt that 2 valve engines delivered but I think modern day electronics on 4 valve engines have got round this
dave

[Michael J]

Originally Posted by galloot633

Id love to know where 5 cylinder thinking comes from , ...

Remember these?

[Rustee]

Originally Posted by galloot633

Id love to know where 5 cylinder thinking comes from , usually designers trying to get the advantages from engines with one less and one more cylinders, the 3 cylinder engine is a good example of this, I always prefered the low down grunt that 2 valve engines delivered but I think modern day electronics on 4 valve engines have got round this
dave

With a 5 cylinder only one piston is at TDC top dead centre firing at any one time so the firing is spread more evenly around each crankshaft revolution. A 4 cylinder engine has two cylinders at TDC with only one of them firing. I think that's why the 5cyl is smoother and makes that lovely sound.

[Steve940estate]

I wonder if the 5 cylinder came about bacause the inline 6 was just too wide for FWD cars.
Did Ford just buy Volvo to get their hands on the 5 cylinder engine ?

[david philips]

there was a big detroit diesel that had 2 pistions per cyclinder,both pistions comeing togeter (almost and the combustion chamber inbetween the two),what i can not under stand with the fuel injection of today and high pressure turbos why do engines need valves operated by a cam snd not go the two stroke cycle instead.

[m0bzy]

Originally Posted by david philips

there was a big detroit diesel that had 2 pistions per cyclinder,both pistions comeing togeter (almost and the combustion chamber inbetween the two),what i can not under stand with the fuel injection of today and high pressure turbos why do engines need valves operated by a cam snd not go the two stroke cycle instead.

Oh I remember them,great engine but very thirsty,Commer also used to make a 2 stroke diesel,sounded great,went like the wind but used to de-coke itself every now and then,the crap out of the exhaust had to be seen to be believed.
Mike

[Daim]

Originally Posted by galloot633

Id love to know where 5 cylinder thinking comes from , usually designers trying to get the advantages from engines with one less and one more cylinders, the 3 cylinder engine is a good example of this, I always prefered the low down grunt that 2 valve engines delivered but I think modern day electronics on 4 valve engines have got round this
dave

Lancia had the very first 5 cylinder engine and it was made, as the 6 cylinder wouldn't fit and the 4 cylinder wasn't powerful enough. They shortend a 6 and made the five. More power and smoothness (then) compared to the 4 cylinders of the time.

Audi then reintroduced them into their old models (80, 90, 100, 200) as a "premium" car needs more than 4 cylinders. They couldn't fit a 6 cylinder, due to the crappey layout of their FWD system, so they HAD to fit a 5 cylinder...

Their "excuse" was:

"Power of a 6 cylinder, fuel consumption of a 4 cylinder"

Biggest lie ever if you ask me.

Volvo's 5 cylinder is based on the old 6 cylinder (inline!) from the 960 made in 1991. The idea was to build an engine system capable of being modular. So they contacted Porsche Engineering (the same company which refined the 1.7l Turbo in the 480 -> not Porsche Cars!!!) and they both constructed the modular "white block" series.

Available in configurations starting at the 6 cylinder (960), the 5 cylinder (850) and then the 4 cylinder (V40/S40 2.0l + T4 - iirc even the 1.8 non GDI). There was even a 3 cylinder version designed but never fitted. We might see it in the near future though.

The reason why there are 2 and 4 valve engines is simple:

It is all to do with torque and power... A 4 valve engine will have most of it's power (torque) up at a higher rpm compared to a 2 valve, where the torque is more so at a low rev range... It hasn't got anything to do with emissions, as a lot of car makers - Volvo included - are going back to 2 valves per cylinder in certain engines -> like the D2.

The reason for a 4 valve engine is simple as well -> the 2 inlet and 2 exhaust valves have a larger surface, than 1 inlet and 1 exhaust valve. This means more air can enter the cylinder and the engine can therefore produce more power...

@ david philips

Why we don't go back to a 2 stroke? Because they only work efficient when on a fixed rev setting. For example on a lorry -> motorway speed at 50 mph (example) reving at around 1500 rpm. This is for a two stroke DIESEL an optimal revrange and the engine will be effiicient. If you take a two stroke petrol, you'll have revs with no end, but no power... Ever driven a two stroke car? I have... Wartburg 353 Tourist (estate) with a 50 hp 3 cylinder 2 stroke. It has NO torque what so ever. You CAN'T use the engine as a "brake" as it has no kind of braking capabilities...

The engine which was spoken about is actually a Junkers opposed piston engine... Junkers -> German. In England they then altered the shape of the engine and made the so called "Deltic".

http://en.wikipedia.org/wiki/Napier_Deltic

Fitted in boats and trains - because a normal car wouldn't be able to use it economically...

[Daim]

Originally Posted by Rustee

With a 5 cylinder only one piston is at TDC top dead centre firing at any one time so the firing is spread more evenly around each crankshaft revolution. A 4 cylinder engine has two cylinders at TDC with only one of them firing. I think that's why the 5cyl is smoother and makes that lovely sound.

Not on a Volvo...

Either 2 or 1 are at TDC and not always either one!

2-2-1-2-2-1-2-2-1...