My trip to Celtic Tuning in Cornwall

[mcbutler]

Hi All,

Yesterday I took a drive down to Celtic in Cornwall, I have used these guys for years and had many vehicles mapped etc there.
Having had catless downpipes fitted to my 35i (and getting no warning lights for the lambda sensors!!) I booked a visit to remove the rear lambdas from the software and get a fresh dyno run in.
Whilst waiting for the work to be done and watching it all via CCTV, I chatted with the guys about a couple of topics.

1. Cone air filters, good idea?.
I was considering these but the guys said absolutely not unless they they come with a cowl to draw cold air from the outside. Reason being is that the hot air under the bonnet is less dense so you get a loss of power. I was advised to simply change the standard filter for a performance one that drops right in which would give me 7-8 BHP (is it worth it?). If an oiled filter is used care must be taken not to over oil or the MAF sensor gets covered and your fuel/air settings go to pot.

2. Why do manual 35i get better BHP figures?.
The DCT box reduces engine power to limit torque through the box as it approaches the change point!

All good info from them that really know so I thought I would share with you all.

[Smartbear]

How did they get on with your car, did they get much more from it?
Rob

[sunnydays]

Are you running a celtic map on the car?

1. Cone air filters, good idea?.

For aesthetics and induction noise, sure. For performance that is debatable.

Pros:
Aesthetics
Induction Noise
Flow more air than the stock box

Cons
Draw in hotter air than the stock airbox

Ultimately, the air gets massively heated by the turbos as it passes through, it is the FMIC's job to cool the air down. I would be surpised if you noticed a performance loss, they also make accessing stuff in the engine bay way way easier. Either is fine, its your preference really.

[R.E92]

Hi All,

Yesterday I took a drive down to Celtic in Cornwall, I have used these guys for years and had many vehicles mapped etc there.
Having had catless downpipes fitted to my 35i (and getting no warning lights for the lambda sensors!!) I booked a visit to remove the rear lambdas from the software and get a fresh dyno run in.
Whilst waiting for the work to be done and watching it all via CCTV, I chatted with the guys about a couple of topics.

1. Cone air filters, good idea?.
I was considering these but the guys said absolutely not unless they they come with a cowl to draw cold air from the outside. Reason being is that the hot air under the bonnet is less dense so you get a loss of power. I was advised to simply change the standard filter for a performance one that drops right in which would give me 7-8 BHP (is it worth it?). If an oiled filter is used care must be taken not to over oil or the MAF sensor gets covered and your fuel/air settings go to pot.

2. Why do manual 35i get better BHP figures?.
The DCT box reduces engine power to limit torque through the box as it approaches the change point!

All good info from them that really know so I thought I would share with you all.

On point 1 they are partially correct. The DCIs have been shown to give either no power increase or in some testing have shown a drop of 1 or 2hp. A better flowing filter will make nowhere near 7bhp, the restrictions in the N54 intake system are the cold side inlets to the turbochargers (most notably the rear turbo), you'd see barely any gain even by removing the air filter completely.
I'm a bit worried that they think the MAF might be damaged by an oiled filter though. There's absolutely 100% no MAF in the N54. There's a MAP sensor in the intake manifold but that's already routinely covered in oil blow-by so a little more would make no difference.

On point 2 they are completely wrong. The DCT only requests a torque drop during the shift, the peak power figure on the dyno will be unchanged. What's more likely happening here is they either use the gear ratios for the manual box when calculating the dyno power or they have some problems with their standard engine tune.

I hope that the guys doing the tuning were a little more clued up as it sounds like you were just given some generic nonsense from the blonde on the till

[Pooltee]

Are you running a celtic map on the car?

1. Cone air filters, good idea?.

For aesthetics and induction noise, sure. For performance that is debatable.

Pros:
Aesthetics
Induction Noise
Flow more air than the stock box

Cons
Draw in hotter air than the stock airbox

Ultimately, the air gets massively heated by the turbos as it passes through, it is the FMIC's job to cool the air down. I would be surpised if you noticed a performance loss, they also make accessing stuff in the engine bay way way easier. Either is fine, its your preference really.

I would have to agree with this also. The air temp post turbo will be higher than any ambient temperature could ever reach, hence the need for the inter cooler. However the intake air temperature sensor reading should assist in making any adjustments required due to temperature difference.

Ultimately it would be not a lot of difference to driving the car in typical summer weather all year round. I would also imagine that with the big grills fitted to the Z4, engine bay temperatures whilst in the move would be close to ambient temp anyway, and the only time there would be an increase is in stop start or slow moving traffic. In either of these scenarios would you really need the possible few BHP’s that were lost through temporary heat soak?

[buzyg]

After chatting with enzed4 in New Zealand. He has cone filters that came fitted. It seems that cone filters without a cold air feed from somewhere, simply soak in the heat from the engine bay and feed hot air into the intake. Not ideal in any engine.

[sunnydays]

After chatting with enzed4 in New Zealand. He has cone filters that came fitted. It seems that cone filters without a cold air feed from somewhere, simply soak in the heat from the engine bay and feed hot air into the intake. Not ideal in any engine.

I had cone filters and can't say I noticed any performance loss. Then again when your running circa 430bhp is 3 or 4 bhp really going to be noticeable either way?

[buzyg]

After chatting with enzed4 in New Zealand. He has cone filters that came fitted. It seems that cone filters without a cold air feed from somewhere, simply soak in the heat from the engine bay and feed hot air into the intake. Not ideal in any engine.

I had cone filters and can't say I noticed any performance loss. Then again when your running circa 430bhp is 3 or 4 bhp really going to be noticeable either way?

Simple principle, keep an engine intake cool and you will get better performance, all other things being equal. It's far more of an issue for forced induction. But most certainly makes a difference in NA engines too.