Tuning a standard SL500 306 bhp

[Craiglxviii]

It is a re map, I cannot see me going into engine mods Mark. If I saw a supercharger cheap, then I might re think. Changing to a 55 is not an option as I am keeping this one, it goes wrong so much it has become a way of life.

A lot of work and ££ in forcing boost to the M113 engine Malcolm... as you yourself first pointed out to me! Sell and get a 55 Kompressor if that's what you want....

 

[LostKiwi]

Thank you very much, this is a new world for me

Camshaft changes are the old traditional way to gain power. Essentially (and apologies if you know this already) to get more power we need to get more air and more fuel into the engine. Fuel is the easy bit - we either increase the time the injector is open or increase the amount it squirts in in the time available (bigger injectors or more pressure - sometimes both).
To get more air in we either have to force it in under pressure (turbo/supercharging) or increase the cross sectional area of the inlet (bigger valves and ports - £££) or increase the length of time the valves are open and how far they open. Thats controlled by the cams.
Changing the cam profile allows the valves to say open longer and also in some cases open further.
The issue is that as we open valves longer we also change the engine characteristics. If we open valves too long the gases can flow back into the inlet from the cylinder at low speed creating a lumpy or erratic idle.
How acceptable this is determines the cam to use. A race cam has timings of 300 degrees or more on both inlet and exhaust. This means the valves stay open for 300 degrees of crankshaft rotation (remember 150 degrees of camshaft rotation = 300 degrees of crankshaft rotation).
A mild factory road cam will typically have valve timings of 240 degrees (or less). A 'fast road' cam will be around 250-260 degrees and a 'rally' cam about 270-280 degrees.

As we increase the duration we move the power further up the rpm range, losing tractability at the bottom for the benefits up high.
With an autobox this can be a little problematic but in general as long as changes are kept sensible its not a problem.

When changing cams its always advisable to replace followers as well as they wear to one another.

 

[SL63 Mark]

Thanks, I discounted the "sprint booster" on the grounds of reversing into my garage The car does feel livelier being de catted, that must give some gain, added to a tune up would this lead to a 20% gain.

I do remember seeing on Top Gear a good tune up could release some extra horses, one of the boys had an old Lambo that was only pushing out 150 bhp or something due to various issues. It might be worth changing the plugs and leads, see if that helps, and making sure everything is in tip top order.

 

[SL63 Mark]

Camshaft changes are the old traditional way to gain power. Essentially (and apologies if you know this already) to get more power we need to get more air and more fuel into the engine. Fuel is the easy bit - we either increase the time the injector is open or increase the amount it squirts in in the time available (bigger injectors or more pressure - sometimes both).

What about Nitrous ?

 

[LostKiwi]

What about Nitrous ?

Yes you can get big improvements with Nitrous but its 'temporary'.

The way Nitrous works is twofold.
1. It has a massive cooling effect increasing the density of the incoming charge. You can expect 10% more power from the cooling effect alone.
2. Its an oxygen carrier (air is 21% oxygen, NOS is 36% oxygen).

The issue with NOS is you need to carry a large tank of the stuff and it runs out very quickly. A 3kg fire extinguisher sized bottle on a system providing 50hp would last about 30 seconds.
If you wanted 100hp you'd need a huge tank.....
Its also not all that easy to get hold of in some parts of the country and it can be expensive.

 

[bembo449]

wouldnt your car need a warning stick to advise of the gas cylinder on board too ?? lol

 

[LostKiwi]

Its exciting when the hose blows off the tank and fills the car with it.......

 

[ajlsl600]

No one that I can see can do that one John, it is almost into AMG territory as it is, with out the cost.

when you already have a car with plenty of power i dont think its really worth it , the makers have spent millions on development to get things how they are ,and be reliable ,at least for during any period when they may be responsible. anything else and yr on yr own .there is also the cost of inssurance on modified cars ?? to be frank my sl 600 has the ability to get my complete attention,as is, i am getting older/slower !! so i will be leaving it that way . i dont think it has much benifit on any resale value either, but i could be wrong

 

[V6Matty]

Go for it Malcolm, you have nothing to loose and as your a car lover it's only right that yours should be that bit quicker/nicer to drive than a standard one ,

oh and while I think about it there is a Kleeman 55 230 sat at MSL at the moment, not sure what's happening to it though

 

[LostKiwi]

Go for it Malcolm, you have nothing to loose and as your a car lover it's only right that yours should be that bit quicker/nicer to drive than a standard one ,

oh and while I think about it there is a Kleeman 55 230 sat at MSL at the moment, not sure what's happening to it though

Nice little project for next winter....

 

[bigasotonuk]

Hi,
I had the 55 engine custom remapped in my C43 as it had been running on the 43 map for nearly 2 years and it made a hell of a difference not in BHP improvement but in torque especially the way it was delivered. Would I get it done again yes definitely.
Something else that no one else seems to of mentioned is replacing the extremely restrictive exhaust manifolds, there quite a few variations available, stubbies, mid-length and long branch. The long branch style seem to offer the biggest gains, though the ones which everyone goes for are the Kleeman mid length, though not the cheapest offer the best quality IMO. http://www.kleemann.dk/
Something that I always wondered about the 500 M113 engine is why it was only 306BHP as the C43 with a 4.3 M113 Engine had the same output 306BHP. One of the ways they gained the extra BHP in the 43 engine was to fit 55 injectors and fuel rail, this enabled more scope for tuning, might be something worth considering.

 

[C350Carl]

Although it's only a modest increase in peak figures of about 7% It depends on when that power comes in. Ideally you need to see a before and after dyno run to see how the power curve looks.

For arguments sake, say your current car now will deliver peak torque at 3500rpm and start to die off at 6000rpm. If when the remap is applied this then makes peak torque come in at 2500rpm and holds it until 6500rpm then you will notice a difference.

Having tuned my cars for years i see a lot of people get hung up on peak output. When they should really be looking at power delivery and how long it maintains peak torque for.

A good indication for you Malcolm will be to see what the power and torque figures are at 5252rpm before and after the map. Torque and BHP are always equal at this point on any petrol car.

 

[umblecumbuz]

My brother and I once supercharged an Austin A35. It took off like a Tesla, but without any roadholding or brakes. The lesson we learned from this, and years of subsequent club racing experience, was that road-usable power is most effective when it comes in at low revs and least effective at high revs.

However you choose to tune, please make sure it is sympathetic to your driving style!

 

[television]

Hi,
I had the 55 engine custom remapped in my C43 as it had been running on the 43 map for nearly 2 years and it made a hell of a difference not in BHP improvement but in torque especially the way it was delivered. Would I get it done again yes definitely.
Something else that no one else seems to of mentioned is replacing the extremely restrictive exhaust manifolds, there quite a few variations available, stubbies, mid-length and long branch. The long branch style seem to offer the biggest gains, though the ones which everyone goes for are the Kleeman mid length, though not the cheapest offer the best quality IMO. http://www.kleemann.dk/
Something that I always wondered about the 500 M113 engine is why it was only 306BHP as the C43 with a 4.3 M113 Engine had the same output 306BHP. One of the ways they gained the extra BHP in the 43 engine was to fit 55 injectors and fuel rail, this enabled more scope for tuning, might be something worth considering.

Thanks Andy, thats a whole new insight again, I do know where there are some nice manifolds going.

 

[television]

Although it's only a modest increase in peak figures of about 7% It depends on when that power comes in. Ideally you need to see a before and after dyno run to see how the power curve looks.

For arguments sake, say your current car now will deliver peak torque at 3500rpm and start to die off at 6000rpm. If when the remap is applied this then makes peak torque come in at 2500rpm and holds it until 6500rpm then you will notice a difference.

Having tuned my cars for years i see a lot of people get hung up on peak output. When they should really be looking at power delivery and how long it maintains peak torque for.

A good indication for you Malcolm will be to see what the power and torque figures are at 5252rpm before and after the map. Torque and BHP are always equal at this point on any petrol car.

More to think about I will check as one tuner shows a graph chart.

As it stands toque is 460 at 2700-4250 the 55 engine 700 at 2750-4000

 

[television]

My brother and I once supercharged an Austin A35. It took off like a Tesla, but without any roadholding or brakes. The lesson we learned from this, and years of subsequent club racing experience, was that road-usable power is most effective when it comes in at low revs and least effective at high revs.

However you choose to tune, please make sure it is sympathetic to your driving style!

I have the same brakes as the early 55 I would only like a little bit more and not spoil the ride in what I have.

 

[Craiglxviii]

Thanks Andy, thats a whole new insight again, I do know where there are some nice manifolds going.

See if there's a nice set for me too please Malcolm. Would be nice to get halfway to a 55's performance without it being noticeable to anything but a strip down...

 

[John Laidlaw]

Although it's only a modest increase in peak figures of about 7% It depends on when that power comes in. Ideally you need to see a before and after dyno run to see how the power curve looks.

For arguments sake, say your current car now will deliver peak torque at 3500rpm and start to die off at 6000rpm. If when the remap is applied this then makes peak torque come in at 2500rpm and holds it until 6500rpm then you will notice a difference.

Having tuned my cars for years i see a lot of people get hung up on peak output. When they should really be looking at power delivery and how long it maintains peak torque for.

A good indication for you Malcolm will be to see what the power and torque figures are at 5252rpm before and after the map. Torque and BHP are always equal at this point on any petrol car.

So in summary Carl, it's how it gets up, how long it stays up for and general stamina ?

 

[LostKiwi]

Hi,
Something that I always wondered about the 500 M113 engine is why it was only 306BHP as the C43 with a 4.3 M113 Engine had the same output 306BHP.

The 4.3 in the CLK produces 275hp - broadly in line with the expected increase in capacity to 5 litres in the SL.

The C43 uses different camshafts (the standard CLK ones are very very mild - inlet duration 200 degrees, exhaust 227 degrees as far as I can make out) so that will account for the difference and is a good example of how camshaft change can influence power.

The C43 has maximum torque of 409Nm at 3250 rpm
The CLK has maximum torque of 400Nm at 3000 rpm
The SL500 has maximum torque of 460Nm at 2750 rpm.

C43 max power is 306 at 5850 rpm (max rpm 6250)
CLK430 max power is 275 @5750 rpm (max rpm 6000)
SL500 max power is 306 @ 5600 rpm (max rpm 6000)

As can be seen the power and torque have both been pushed slightly further up the rev range on the 4.3 litre engine.

Larger engines are usually more tolerant of wilder cams than small ones. This can be seen in the comparison between the CLK and SL above as I would imagine the cam profile on the two of them will be the same.

In my Mini days I had a 1275 Cooper S and a mate had a 970. Both these engines use the same cylinder head and have the same bore and valve sizes.
We both went to a full race camshaft (300 degrees inlet and exhaust). Mine would idle at 1000rpm but his wouldn't idle at less than 1300rpm.
Mine also came 'on cam' at 3000rpm but his was only coming 'on cam' at 4000rpm. 'On cam' is a phrase used to refer to when the engine starts to pull smoothly and gas flow in the ports becomes laminar with no turbulence caused by gas flowing the wrong way as a result of the valve duration and overlap (where both valves are open at the same time - for this camshaft 95 degrees).

 

[television]

Wow all you guys do know your stuff, been reading on 55 camshafts, down pipes and all the rest, but I will never do all that, yes add a Kleeman kit, but the cost is more than the car is worth, reading threads from those that have just got the extra 20hp and 20 torque are happy with that and the car is better, its very low cost and no one can see it, it does shift the torque band a bit lower RPM, so that is a good thing from what I read. It still stays in my mind as to what you can believe. I will talk to Colin when I am down there in the morning.