38 replies to this topic

[benw]

Okay, so what we're saying is that an engine is made with it's fundamental parts (Pistons, conrods, cam shafts etc.) designed for either performance or longevity or a mixture of both. The software in the ECU is also designed with either performance, longevity, emissions etc. in mind. Tuning companies can adapt the software on the ECU to move the scale towards performance but will always be limited by the actual 'Hardware' that's in the engine. Therefore, it's primarily the fundamental engine parts that affect engine performance. One 2 litre engine can produce much more power than another 2 litre engine because it's parts are deisgned to produce performance but won't last very long and may not be the most efficient. The alternative is to use expensive 'Exotic' engine parts. They don't necessarily increase performance but allow you to use more performance without trading off so much longevity. Does that sound about right? And have you noticed that I have these sudden inquizitive bouts every now and then? I'd be up all night if I didn't figue it out!

[JG]

yeah i think that sounds about right. The only reason though that manufactures use different metals such as titanium in highly tuned engines, is simply that if they didnt the engine would desintegrate ( or it would not last the required time). Manufatures often get fundemantal things wrong in engine design. Only need to look at the VANOS unit on bmws staight 6, 60% failure usually resulting in engine failure. The vx works so well because as has been said on here over and over the engine is very unstressed, coupled with a light car, makes a very reliable, loooong distance between service etc etc, fun car to drive. It also gives people who wish to the oportunity to upgrade without the worry that it will break 20 miles down the road. edited to add my name: James

Edited by JamesGray, 27 July 2004 - 08:56 AM.

[WoodenDummy]

That's a good way of putting it, the great thing about the 2.2 is it is understressed but it's also cheap. If you blew an engine on track it wouldnt cost much at all to replace. The same goes for the Elise, MX5, MR2 ect... I can't say the same for the S2000 or Boxster. 2.2 is a little big, you'd get the same power from a 2.0 but it's just the engine that Vauxhall probably had the most of or something. s'Good engine, suits the car very well.

[paulb]

It's reasonably straightforward to take the 2.2 to around 190 bhp (AmD stage 3 and inlet manifold) but beyond that would start to get very expensive. Throttle bodies are needed to get more air into the engine (at higher revs, more air is needed to deliver the required amount of air per cycle). By using individual butterfly or roller barrel throttle bodies per cylinder, it is possible to get much more air in to the cylinders, whilst keeping each feed small enough to swirl the air enough to mix the air and fuel properly. The other way to further increase power is to change the cams to ones that lift higher and stay open for longer. Longer duration causes very lumpy idle and kills torque lower down, but allows for higher peak powers. Higher lift can lead to their own problems - with pistons and valves potentially colliding. Gas flowing and porting a cylinder head and using smaller stemmed valves can also lead to getting more air in (and hence more power). If the engine is planned to rev harder than designed, it is normally necessary to fit stronger valve springs to ensure they shut the valves quickly enough and cope with higher speeds of operation. To enable an engine to rev higher, it is normally necessary to use stronger and lighter internals to lower the stresses. This is why people upgrade these parts to 'forged' rather than 'cast' Changes typically involve pistons, con-rods and often cranks. For real extreme engines, a billet crank is used which is machine from solid steel. These typically cost £3,000 to £5,000 alone. An F1 engine produces largely similar torque to a 3.0 road engine. However, by revving to over 18,000 revs, it is able to produce massive power. The V10 is the prefered configuration for high revving engines for a number of reasons. For more revs, the smaller each cylinder capacity the better as pistons are lighter and the stroke is typically smaller. The smaller the stroke (how much the piston moves up and down on each cycle) the lower the acceleration on the conrods and pistons and the lower the forces. This puts lower strain on the internals of the engine. However, you need to have enough cylinder area to get fuel and air in and exhaust out efficiently which means you can't you too far. Most engine designs are designed to be close to 'square' - stroke and bore are equal as this gives the best compromise between torque and power (i.e. cylinder head area and ability to rev). I've been spending a lot of time recently studying the Rover K series engine so will use that as an example. The engine was originally designed as a 1.4 and then bored out to make a 1.6. The 1.6 is basically square with a 80mm bore and 79mm stroke. The 1.8 (as in the Elise) is a stroked version of the 1.6 with the same 80mm bore and an 89mm stroke. This extra stroke and inherent less strong design means that the 1.8 can rev less high than the 1.6. This means that the peak power obtainable from either engine (in full race trim but reasonable race reliability) is actually very similar. To create a very high power Elise (e.g. 220 bhp 1.8), very little of the original engine remains. Pistons, cylinder liners, conrods, bearings, valves, springs, cams, followers, etc all have to be changed. The crank may be left but may be swapped for a stronger unit to increase reliability. All that really remains is the block casting, sump and head. Having said that the sump may be swapped for a dry sump version and the cylinder head will be ported, flowed and fitted with bigger valves. The exhaust will have been swapped and will have no cat. The entire induction system will have been junked for direct to head throttle bodies. So, not straightforward at all. I looked at going further when I had my VX - I really wanted about 220 bhp out of my 2.2. Throttle bodies and some wilder cams should have enabled this power level, along with forged rods and pistons and uprated valve springs and followers. However, there isn't room to get decent length trumpets on throttle bodies in the NA without hitting the fireproof bulkhead between engine and driver (which I wanted to leave!!!) The K series in the Elise is the other way round, so induction can protrude into the boot area. The other problem with the VX installation is that the exhaust manifold is very short. For high top end power you want a 4:2:1 manifold with probably 32" or so primaries. Again this is not possible with the NA as the exhaust ports on the engine are too near the back of the car. There is also a very sharp turn in the exhaust route, which further hampers power gains. So, I sold my VX... Paul

[paulb]

Others have written pretty much the same things while I was typing, oh well... Vauxhall used a 2.2 as they don't actually have a 2.0 NA in their range at the moment.

[WoodenDummy]

2.2 it does seem like a strange number doesn't it. Not many of them around it's normally a 2.0 or a 2.5. Why didn't you just go for a SC? You'll get the 225 you looked for and it would still drive like an NA.

Edited by WoodenDummy, 27 July 2004 - 09:41 AM.

[Gedi]

Does that sound about right?

And to Paul for his lengthy tech post

Edited by Gedi, 27 July 2004 - 09:52 AM.

[paulb]

2.2 it does seem like a strange number doesn't it. Not many of them around it's normally a 2.0 or a 2.5.

Why didn't you just go for a SC? You'll get the 225 you looked for and it would still drive like an NA.

Dunno why 2.2, but Vauxhall also have 3.2 which is unusual. It must be one of the bigger 4 pots around as 2.5s are normally sixes.

Didn't want supercharger as forced induction changes the feel of the car (big lumps of low down torque whereas I wanted a tuned, revvy normally aspirated engine).

I actually think the 2.2 is very good (a lot of the VX 16v are) but won't get the development focus as it is over 2 litres (a typical motorsport threshold)

[Gedi]

Dunno why 2.2, but Vauxhall also have 3.2 which is unusual. It must be one of the bigger 4 pots around as 2.5s are normally sixes.

What about VW's 2.9 V6 then. 0.483cc per chamber

heh

[paulb]

You what? Have you lost it Gedi?

I said that 2.2 was big for a 4 pot... And you demonstrated a six pot 2.9. Don't understand your point.

And I presume it is actually 0.483 litres per chamber...

The 2.2 is 0.55 litres per cylinder.

There are some bigger ones around but it isn't common. One of the biggest 4's that I know of it the 3 litre in the Porsche 968 with 0.75 litre per chamber.

There are lots of real big V8s with big chambers, but they are hardly revvy...

[paulb]

Oh Gedi, I should also point out that your sig sucks. inv log (x) is normally written at 10^x

[WoodenDummy]

Think about it they did a V5 as well, which never really maked much sense.

[Gedi]

You what? Have you lost it Gedi?

chill out, I was meerly pointing out the odd size of 2.9 instead of 3.0

Oh Gedi, I should also point out that your sig sucks.

inv log (x) is normally written at 10^x

Aren't we in a bad mood today. Its just a joke, your not meant to try solve it. Solving it would obviously not give you a decimal answer, so you can't phone me anyway

[paulb]

i am chilled - just at work! I guessed that it wouldn't be solveable due to the use of 'i' (or 'j' as I like to call it as an electronic engineer). So I guessed that meant it would be an imaginary phone number... In general, there are many more engines just under than just over 2.0 or 3.0 (such as the 2.9 VW - now I understand). There is also the Peugeot 1.9 that springs to mind. I guess we really shouldn't venture into the world of the 1275 GT Mini, 2.25 litre Land Rover or 1750 Austin Maxi!!!

[caleebra]

Dunno why 2.2, but Vauxhall also have 3.2 which is unusual.

I seem to recall the reason for the 2.2 was something to do with emissions regulations/economy and retaining said low down torque

It's a pity that the Z22SE wont get the development focus that the C20XE got because of that motorsport threshold Dont think GM would have given a toss about that during the design of the thing

The 2.2 Ecotec....

http://www.gm.com/au...news/press1.htm

There was also one about a the tuning of an Ecotec block to over 1000hp, but I couldn't find it. This is a bit about it though...

http://www.gm.com/co...y/FWDEngine.htm

edit: found it: http://www.year2032.com/ecotec.htm

Edited by caleebra, 27 July 2004 - 11:30 AM.

[TurboTomato]

I would have loved to have the engine and gearbox from my old Civic TypeR in the Speedster. You can make a reliable engine with 100hp/liter, but it's not as cheap as just using a tractor engine like the one Opel used.

I really miss listening to the engine at 8300 rpm before every gearshift.

Same here

[WoodenDummy]

the timing chain with hydraulic tensioner requires no maintenance over its entire working life

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[Duncan]

As stated before, there's an optimum size for each cylinder, hence why 1.6's tend to be fours, 2.5l sixes etc. Another tuning point is blueprinting - The eninge would shake itself apart if the moving parts (ie pistons, rods etc) weren't properly and the thing built to tolerance. Professional engine builders will balance a set of pistons so they way as near as damn it the same, reducing load on bearings etc. But as ever in production engines higher tolerances mean more money, so we you end up with the 200bhp +20/-3bhp turbo engine. But think yourself lucky. At least the 2.2 is an alloy block and not one of those smelly cast iron things the desended from a steam engine...

[Makinen]

There are lots of real big V8s with big chambers, but they are hardly revvy...

I used to run a 6,0 V8 and changed gear at 6500rpm. It was a bit weak below 3500rpm, but I could live with that.

I watched a rerun of a NASCAR race yesterday. Their engines are 5,7 or 5,8 liters and they were up at 9600rpm...for 400 miles... Those are pushrod engines of course.