View Full Version : Does Cam Timing do anything?


Roulette
04-02-2008, 06:13 PM
Tuning turbo does lot.
Tuning NOS also does a lot.
Lowering a car has various effects.
Sway bars to Max makes a car turn-in much better.

And various other tunings have noticeable effects depending on race type.

BUT:

Does Cam Timing do anything?ANYTHING???

afaik, cam timing, in this game, does n.o.t.h.i.n.g.

I'd expect a change in shift points and an increase on peak BHP, since that's how cam-timing effects an engine.

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Anyone else have comments on effectiveness of the various tuning options?

Suggestions for future tuning options? (I'd like to see diff-control - might make AWD cars useful)

Zpectre
04-02-2008, 10:05 PM
Not that I know of - didn't see any gain/loss in speed. It does have a small effect on power ratings though, but it's a rather odd one since I usually gain 1 bhp by leaving it in the middle.

QUINTIN
04-03-2008, 12:15 AM
Change it and have a look at the rpm. of the torque.

white_rabbitt
04-03-2008, 03:43 AM
it DEFINETLY does something, try this, take a car that is slow to pick up after braking and move the slider to the left, you will most definetly notice a difference

Roulette
04-03-2008, 10:04 AM
it DEFINETLY does something, try this, take a car that is slow to pick up after braking and move the slider to the left, you will most definetly notice a difference

That's exactly the kind if thing I'm looking for - will check it out, Thx :)

NFS Feedbacker
04-04-2008, 12:55 AM
As far as my common sense goes, advancing the cam timing should allow more inlet air due to the greater time available and this should help in generating more power, specially on turbocharged engines. But you never know until you experiment:\

NinjaX
04-04-2008, 04:19 AM
Cam timing is what part or your revs you want the torque to come at. so if you put it to retard, you will feel a little more power in the lower revs, and advance, more power up top.

white_rabbitt
04-05-2008, 09:40 AM
yeah what he said

NinjaX
04-05-2008, 08:45 PM
See its simple.

Roulette
04-05-2008, 10:17 PM
Cam timing is what part or your revs you want the torque to come at. so if you put it to retard, you will feel a little more power in the lower revs, and advance, more power up top.

That's the wrong way round. I see EA have it wrong too.

Retarding cam timing means that inlet/exhaust gas-flow must be faster to take advantage of the valves opening and closing later. Imagine an engine spinning like mad with gasses going in and out, valves opening and closing at optimum. Then imagine it spinning even madder - if valves open/close at the same time as before, but with a higher gas-speed, then valves open/close cycle will be a little too soon for optimum filling of the combustion chambers. Remember - it's only the inlet that counts here as we're changing timing of a cam, not changing the profile - exhaust gasses are forced out under pressure anyway.

Biggest gains on real cars are to be had when the manufacturer did something stupid to the cam timing for emissions reasons or whatever.

That's how cam timing works. But not in this game.

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I tried taking notice of possible quicker gear changes on far-left cam timing - jury's still out, not noticed a change yet but only tried on S3 so far - not ideal car to try it on as the gear changes are slow because it's AWD (Does anyone else find *all* AWD cars gear changes are slow?)

white_rabbitt
04-06-2008, 03:34 AM
its not about quicker gear changes, its about having torque for acceleration without downshifting for the ppl that play on auto or are lazy with their shifting. and I didnt necessarily mean far left timing sometimes that hurts the cars ability to accelerate near redline.

you have a decent explanation in there somewhere, in reality roulette, you really dont want to mess with the cam timing of a car, thats a really good way to bend valves and damage pistons, well, maybe a very little adjustment on DOHC engines, but that would be to change when the valves open in relation to each other, i.e. to change the "OVERLAP" (when the valve are open at the same time) for forced induction. the "TIMING" of the cam is built in otherwise, so changing it requires changing the cam.
I think that what they meant was ignition timing which would make the slider right. seeing as how the speed of combustion is a constant while the speed of the engine components is variable, you have to advance it at high rpm to get the most efficient use of the burn, and retard it at low rpms to prevent detonation or "PING". maybe thats backwards, I havent thought about it iin a while.

I know this isnt a real good explantation, I really dont want to spend all night explaining the technicalities of the workings of an engine.

Roulette
04-06-2008, 10:42 PM
No idea where I got the idea you were talking about gear changes from, lol. Pickup after braking to lower revs - yes, will check that out. I do deliberately down-shift quite a lot for when engine bogs - maybe I'm doing it automatically now without taking notice of if it's actually bogging or not.

Totally with you on ignition timing - mixture has to be set alight earlier at higher rpms or the peak part of the burn is too late because piston is already too far down the bore by then. Did EA mess up and call it cam-timing when they meant Ign timing? Wouldn't surprise me - They say "slide to the left for low end torque" which is retard... Er... no?

You've taught me something about DOHC - I'm used to single cams in A-series, CVH and Golf engines - overlap is obviously fixed by the cams profile. On a DOHC, inlet and exhaust are totally separate camshafts so you can do real work changing the optimum rev-range just with a pair of vernier wheels. That had never really occurred to me as I've not made any cam choices for DOHC engines. Thanks :)

On A-series engines, the cam timing was nearly always miles out... You can buy offset woodruff keys in known degrees of offset to put it right - that's how bad British engineering really was back then, lol. I think that's why vernier gears are quite popular over here.

NFS Feedbacker
04-07-2008, 12:08 AM
Does cam timing have anything to do with engine braking? Because in suitable conditions of valve overlap, when both valves are closed during exhaust stroke, the engine would work like a compressor. But I suppose it only changes when brakes are applied.

white_rabbitt
04-07-2008, 09:34 AM
engine braking occurs when there is not enough fuel in the cylinders to support the rpms, the higher the compression, the more noticeable this is.

roulette, you werent wrong, i was just trying to clarify.

the small adjustments you are talking about with the woodruff keys are to move when the inlet opens without changing the cam. thank you emissions regs (sarcasm)
optimally, you want the inlet valve to begin opening just before tdc on the exhaust stroke, and close just before bdc on the intake stroke, this gives the air fuel mix an additional moment to vaporize under vacume. then you want the exhaust valve to open just before bdc on the power stroke, since the usefulness of the explosion is spent, and close just after tdc.
on forced induction engines the inlet valve should stay open until a little after bdc on the inlet stroke, optimally right before boost pressure is overcome by the upward force of the piston.

hope this helps

NFS Feedbacker
04-07-2008, 10:25 AM
Gotcha dude. Thanks for clearing my concepts.