N20 vs N52 vs N54 Engine

[Vonlipvig]

Celtic maps are not generic, they are developed in house and tweaked individually for each car if done on site. I think the guys at Celtic would be quite unhappy to hear people calling them 'generic'.
My 35i was done in house at their facility in Cornwall, it took around 2.5 hours with the ecu being removed and retweaked upstairs over and over again. My particular engine at its individual 'best tune' was at 365BHP and 400lb/ft torque. Not too bothered about BHP as its torgue that gives the accelaration, drivability.
AND its done on a rolling road so I know what I am getting, not what it says on a box.
After fitting catless downpipes Celtic remapped it for me to 395 BHP and 415lb/ft and I LOVE IT

Sounds good too

 

[R.E92]

I very much doubt anyone could realistically use anything over 280bhp to it’s full potential on public roads. Perhaps a trained professional driver
BHP figures have just become a marketing statistic and ‘who has the biggest pair’ but come on, if you are putting down 400bhp to it’s full potential around Wales, or on the M1, you won’t last long. Financially or otherwise!

Even 280 is enough to get into some serious trouble.

A z4 20i stock probably is quicker than 90% of cars on the road.

If by using the car to its full potential you mean pulling the maximum G around each corner and hitting the speed limiter on every straight road then you'll find that nobody uses their car to it's full potential on public roads. That doesn't mean to say there's no increased enjoyment when driving a 911 Turbo S along some good roads vs driving a Vauxhall Astra, both will reach the speed limit!

There's some truth behind the saying that a car has too much power for the road but that term usually gets bounded around in supercar reviews when the horsepower numbers climb towards four digits.

Celtic maps are not generic, they are developed in house and tweaked individually for each car if done on site. I think the guys at Celtic would be quite unhappy to hear people calling them 'generic'.
My 35i was done in house at their facility in Cornwall, it took around 2.5 hours with the ecu being removed and retweaked upstairs over and over again. My particular engine at its individual 'best tune' was at 365BHP and 400lb/ft torque. Not too bothered about BHP as its torgue that gives the accelaration, drivability.
AND its done on a rolling road so I know what I am getting, not what it says on a box.
After fitting catless downpipes Celtic remapped it for me to 395 BHP and 415lb/ft and I LOVE IT

This is a little off-topic but I'm guessing since the OP's next question will be where to get a remap for his new 35is I'll jump the gun;

Celtic do just supply generic tunes. Running it up on the dyno and making sure the AFR and boost are healthy doesn't really count as a custom tune. The fact they removed the ECU for a bench flash worries me a bit, it seems they are either using some really outdated flashing method as the MSD80 and MSD81 ECU have been flashable via OBD for nearly a decade now, the keys required to read and write to the ECU were cracked in 2011 and nobody has bothered bench flashing them since.

The big giveaway that they are generic should be that Celtic offer such a wide range of tunes for almost all models of car. They are just a reseller of tuning files. The likes of EVC who make WinOLS provide access to a database of generic maps for pretty much every engine out there, the likes of Celtic will purchase the a flashing tool like KESS or KTAG which lets them flash almost any car out there and then subscribe to a service that gives them to base tunes to flash, they typically will pay a small fee per tune, run the car up on a dyno for a printout and then charge the customer between £300 and £500. The big costs for that setup will be the flashing tools and dyno, the maps cost them a few quid each time.

You mention that they now have something called eMotion2+, a flashing tool that the customer can use. I had a quick look into it and it turns out they are just re-selling an Alientech Powergate, probably at a nice fat profit margin. This is a fairly common device but nobody uses them since MHD came out. I had one of these back in 2013 when it was branded as the OpenFlash Tablet, it only cost me about £250 back then.
https://www.emotion-tuning.co.uk/
https://www.alientech-tools.com/en/powergate3/

It seems Celtic are 7 years behind the curve

 

[GoSteve]

My thinking so far
The responses to this dilemma N20 vs N52 vs N54 have been brilliant. I think it fairly reflects what anyone faces when choosing which Zed to buy. I found an excellent website (which everyone probably already knew about) but just incase anyone didn't, https://bmwtuning.co. They review all BMW engines, their pros and cons. The outcome the same as here.

So, I sold my TTS partly because I hated with a passion, the DSG gearbox, and mostly because I could afford an E89 Z4. A car I fell in love with the first day I saw the E89 ten years ago. Maybe the BMW DSG in the 35i is better. I will test drive one and see. So, what to buy, 35i manual vs a 20i auto. Bearing in mind the 2.0 N20 will need a remap at £400. Both cars would benefit from a warranty, as mentioned previously, but I wonder how far your claim would go if your engine was remapped :? N54 or N20.

N54
So, a 35i manual, whilst not quite so nimble will 1) sound awesome, 2) save the remap cost, 3) save a conversation with your insurer, 4) and less likely to fall foul of any conversations with your warranty company should it need some costly ancillary engine repairs. Unless I remapped that too. (which I might ).

N20
I have driven a 28i auto and loved it. A remap to 280 bhp would only improve it. Plus it's a little more nimble. But there is a justified spectre of engine failure. The plethora of other small issues are shared on the N54 anyway. But the elephant in the room is that a 20i is SIGNIFICANTLY cheaper to buy used than an equivalent 35i.

So, whilst I haven't completely decided on which to buy, I think I have a really good handle on the risks, benefits and potential costs of each. N20 2.0 auto remapped to 280 bhp or 35i manual. My preference is the 35i. But finding one in the right colour, realistically priced might prove a greater challenge. But I am not nearly so worried about the N20 engine as I was.

 

[Busterboo]

This is a little off-topic but I'm guessing since the OP's next question will be where to get a remap for his new 35is I'll jump the gun;

Celtic do just supply generic tunes. Running it up on the dyno and making sure the AFR and boost are healthy doesn't really count as a custom tune. The fact they removed the ECU for a bench flash worries me a bit, it seems they are either using some really outdated flashing method as the MSD80 and MSD81 ECU have been flashable via OBD for nearly a decade now, the keys required to read and write to the ECU were cracked in 2011 and nobody has bothered bench flashing them since.

The big giveaway that they are generic should be that Celtic offer such a wide range of tunes for almost all models of car. They are just a reseller of tuning files. The likes of EVC who make WinOLS provide access to a database of generic maps for pretty much every engine out there, the likes of Celtic will purchase the a flashing tool like KESS or KTAG which lets them flash almost any car out there and then subscribe to a service that gives them to base tunes to flash, they typically will pay a small fee per tune, run the car up on a dyno for a printout and then charge the customer between £300 and £500. The big costs for that setup will be the flashing tools and dyno, the maps cost them a few quid each time.

You mention that they now have something called eMotion2+, a flashing tool that the customer can use. I had a quick look into it and it turns out they are just re-selling an Alientech Powergate, probably at a nice fat profit margin. This is a fairly common device but nobody uses them since MHD came out. I had one of these back in 2013 when it was branded as the OpenFlash Tablet, it only cost me about £250 back then.
https://www.emotion-tuning.co.uk/
https://www.alientech-tools.com/en/powergate3/

It seems Celtic are 7 years behind the curve

And this, ladies and gentlemen, is why I wrote my post.

Da, dah!

 

[enzed4]

Maybe the BMW DSG in the 35i is better. I will test drive one and see.

Be careful not to judge too quickly if you test the DCT in a 35i. I would say most people are fairly underwhelmed with it when it's cold and you're just pootling along in normal traffic. It's hard to describe, but it doesn't feel very 'engaging' and just kind of gets the job done.
BUT - get it warmed up, drive it around some twisty bits, put it in Sport (or Sport + if you're tired of living :lol: ) and the difference is night and day. The quick shifting, pops and crackles when you lift off at just the right point are just so much fun .
Just my experience, anyway.

 

[mcbutler]

I very much doubt anyone could realistically use anything over 280bhp to it’s full potential on public roads. Perhaps a trained professional driver
BHP figures have just become a marketing statistic and ‘who has the biggest pair’ but come on, if you are putting down 400bhp to it’s full potential around Wales, or on the M1, you won’t last long. Financially or otherwise!

Even 280 is enough to get into some serious trouble.

A z4 20i stock probably is quicker than 90% of cars on the road.

If by using the car to its full potential you mean pulling the maximum G around each corner and hitting the speed limiter on every straight road then you'll find that nobody uses their car to it's full potential on public roads. That doesn't mean to say there's no increased enjoyment when driving a 911 Turbo S along some good roads vs driving a Vauxhall Astra, both will reach the speed limit!

There's some truth behind the saying that a car has too much power for the road but that term usually gets bounded around in supercar reviews when the horsepower numbers climb towards four digits.

Celtic maps are not generic, they are developed in house and tweaked individually for each car if done on site. I think the guys at Celtic would be quite unhappy to hear people calling them 'generic'.
My 35i was done in house at their facility in Cornwall, it took around 2.5 hours with the ecu being removed and retweaked upstairs over and over again. My particular engine at its individual 'best tune' was at 365BHP and 400lb/ft torque. Not too bothered about BHP as its torgue that gives the accelaration, drivability.
AND its done on a rolling road so I know what I am getting, not what it says on a box.
After fitting catless downpipes Celtic remapped it for me to 395 BHP and 415lb/ft and I LOVE IT

This is a little off-topic but I'm guessing since the OP's next question will be where to get a remap for his new 35is I'll jump the gun;

Celtic do just supply generic tunes. Running it up on the dyno and making sure the AFR and boost are healthy doesn't really count as a custom tune. The fact they removed the ECU for a bench flash worries me a bit, it seems they are either using some really outdated flashing method as the MSD80 and MSD81 ECU have been flashable via OBD for nearly a decade now, the keys required to read and write to the ECU were cracked in 2011 and nobody has bothered bench flashing them since.

The big giveaway that they are generic should be that Celtic offer such a wide range of tunes for almost all models of car. They are just a reseller of tuning files. The likes of EVC who make WinOLS provide access to a database of generic maps for pretty much every engine out there, the likes of Celtic will purchase the a flashing tool like KESS or KTAG which lets them flash almost any car out there and then subscribe to a service that gives them to base tunes to flash, they typically will pay a small fee per tune, run the car up on a dyno for a printout and then charge the customer between £300 and £500. The big costs for that setup will be the flashing tools and dyno, the maps cost them a few quid each time.

You mention that they now have something called eMotion2+, a flashing tool that the customer can use. I had a quick look into it and it turns out they are just re-selling an Alientech Powergate, probably at a nice fat profit margin. This is a fairly common device but nobody uses them since MHD came out. I had one of these back in 2013 when it was branded as the OpenFlash Tablet, it only cost me about £250 back then.
https://www.emotion-tuning.co.uk/
https://www.alientech-tools.com/en/powergate3/

It seems Celtic are 7 years behind the curve

Then you would need to explain why they have several project cars outside for map development!!!!

 

[R.E92]

Then you would need to explain why they have several project cars outside for map development!!!!

All tuning shops have shop cars. They serve as a good advertising tool and can be written down as a business cost.

It turns out one of the tools Celtic use it the Autotuner: https://www.autotuner-tool.com/en/presentation
You can have a read up there and see that there actually isn't any ability for them to customise the map in any way. If Celtic have a problem with the tune they have to contact the supplier and request a fix. Hence why you had to wait 2.5hrs for a tune!

 

[Anonymous]

R.E92's observations are interesting..

For those that were/are in the IT business its no suprise that a retailer /distrubutor is using/bundling other components up..

IMHO it boils down to the trade off of reputation/track record/price/support etc

Celtic does seem to have a good reputation and delivers for most a noticeable improvement with the assurance that others have gone before..

A geek/anorak/techie can always ring more out either through naivety, ignorance, trade offs, reliablity or plain just more sweat at a problem..and maybe inspiration / lateral thinking..

It depends whether you want something predictable /reliable/peace of mind or willing to be more adventurous accepting its not for everyone..

Of course the safest option is to leave it stock or better still buy the most detuned version possible..

 

[enuff_zed]

I am still intending to go to Celtic as soon as we are able, and getting the 280 map on mine.
I fully understand that with time, patience and endless tweaking you can optimise the performance of each individual engine, but do I need it? Probably not.
BMW mass-produced this engine and produced a variety of generic maps to suit it, all well within it's potential performance envelope.
For me, to replace this map with another generic one, still well within that performance envelope, but nearer the upper end of it, will be more than satisfactory.
Especially as the reality is that I will very rarely (probably never tbh) exploit all of that performance.
From what I have read on here, the extra torque gained makes it a very usable B-road car without having to rev it to the extremes anyway.

As always, it is 'horses for courses' and those members that are channelling Senna will have different requirements to mine.

 

[R.E92]

R.E92's observations are interesting..

For those that were/are in the IT business its no suprise that a retailer /distrubutor is using/bundling other components up..

IMHO it boils down to the trade off of reputation/track record/price/support etc

Celtic does seem to have a good reputation and delivers for most a noticeable improvement with the assurance that others have gone before..

A geek/anorak/techie can always ring more out either through naivety, ignorance, trade offs, reliablity or plain just more sweat at a problem..and maybe inspiration / lateral thinking..

It depends whether you want something predictable /reliable/peace of mind or willing to be more adventurous accepting its not for everyone..

Of course the safest option is to leave it stock or better still buy the most detuned version possible..

Most tuning shops operate the same way. There isn't any UK tuners that I know about that offer truly custom tunes with custom logic. Even big names like Litchfield and Evolve are just resellers for the most part. Litchfield do have their own R&D on the GTR platform but from what I've seen in their BMW tunes they are just resellers.

It really boils down to economies of scale in the tuning world. Celtic might remap 50 N54 engines in a year with a tight profit margin, MHD is used by over 50,000 people on the N54 engine alone so they can afford to employee a combination of both engine specific tuners to create a tune and a software developer to reverse engineer the DME code and write custom logic.

In my experience the failure points on the N54 engine are not aggravated by tuning at all. Fuel pumps, injectors and water pumps go at the same rate regardless of power output. Turbocharger failures are rare and seem to be caused more by the wastegates failing than the CHRA or blades falling apart.

 

[Anonymous]

In my experience the failure points on the N54 engine are not aggravated by tuning at all. Fuel pumps, injectors and water pumps go at the same rate regardless of power output. Turbocharger failures are rare and seem to be caused more by the wastegates failing than the CHRA or blades falling apart.

All noted I think the long history / volume of the N54 means that there is less risk as you say..

My comments were more addressed to the N20 where there is not the samel level of empirical evidence and the headroom is not so high for mistakes given its higher specific output..

 

[Big Bad Boris]

So, N20, N52 or N54. What are the risks, issues, reliability and possible costs to fix.
I think we could safely say the N52 is fairly bullet proof. But what about the N20 and N54 both can have issues. What are those issues and which engine is the best balance against risk and performance.

N54 is generally pretty reliable, just the ancillaries around it that can have issues. Prices depend on if you are DIYing or getting bent over by a dealer.

Common Faults
Injectors
High Pressure Fuel Pump
Oil Filter Housing Gasket
Valve Cover Gasket
Valve Cover (Cracking)
Turbo Wastegates
AC Pulley
Engine Mounts

Other than the above it is a solid engine.

Edit: They will also make circa 450bhp with a custom remap and have a great tuning platform and community.

I’d like to explore these issues a little further as I have noticed quite a few unmolested 35i variants creeping into my price range over recent weeks, making them a viable option (to a 30i), from a purchase price perspective at least.

Obviously there isn’t a hard and fast rule as to when the items noted above will begin to empty your wallet. However, I assume mostly they are mileage, rather than age related (or maybe not?). If mileage is the key thing, it seems there might be 2 good times to buy these models and one to avoid. It would seem low mileage cars are “relatively” less likely to suffer from failures of HPFP and injectors etc and hence are a much safer bet, whilst high(ish) mileage cars, with good Verifiable history may have already had a lot of the referenced issues occur and the large bills dealt with. Leaving the the mid mileage versions waiting in your garage to ruin you at their convenience.

Hopefully the wise men will be along to pour scorn on my theory. But if it stacks up at all and there is any sense in my musings where are those mileage lines, say up to 40k miles for a low mileage “safe” example and 80k for a higher mileage version where many issues may have been already dealt with, leaving the 40-60k middle mileages being the ones where the big bills are imminent.

 

[brillomaster]

i believe the HPFP issue was far more prevalent on US cars, less of an issue of UK cars.

when i bought a x35i (it was actually an E92 335i) the main thing i was advised to check for was the turbo wastegate, and they way to check it was get the bonnet open, rev the engine and listen for any tinkling noises from the turbos. no tinkling noise to be heard, so went ahead and purchased the car. shortly after remapped it up to ~360bhp, and ran it for a year, completely trouble free

i must say, 360bhp feels gorgeous. the remap meant the turbos kicked in a tad lower, but more importantly maintained puff right up the rev range. remember once doing the nascar rolling start leaving a 50mph average speedcamera zone... think the speedo read 140 and was still pulling strong when i decided perhaps i should lift :roll:

 

[R.E92]

So, N20, N52 or N54. What are the risks, issues, reliability and possible costs to fix.
I think we could safely say the N52 is fairly bullet proof. But what about the N20 and N54 both can have issues. What are those issues and which engine is the best balance against risk and performance.

N54 is generally pretty reliable, just the ancillaries around it that can have issues. Prices depend on if you are DIYing or getting bent over by a dealer.

Common Faults
Injectors
High Pressure Fuel Pump
Oil Filter Housing Gasket
Valve Cover Gasket
Valve Cover (Cracking)
Turbo Wastegates
AC Pulley
Engine Mounts

Other than the above it is a solid engine.

Edit: They will also make circa 450bhp with a custom remap and have a great tuning platform and community.

I’d like to explore these issues a little further as I have noticed quite a few unmolested 35i variants creeping into my price range over recent weeks, making them a viable option (to a 30i), from a purchase price perspective at least.

Obviously there isn’t a hard and fast rule as to when the items noted above will begin to empty your wallet. However, I assume mostly they are mileage, rather than age related (or maybe not?). If mileage is the key thing, it seems there might be 2 good times to buy these models and one to avoid. It would seem low mileage cars are “relatively” less likely to suffer from failures of HPFP and injectors etc and hence are a much safer bet, whilst high(ish) mileage cars, with good Verifiable history may have already had a lot of the referenced issues occur and the large bills dealt with. Leaving the the mid mileage versions waiting in your garage to ruin you at their convenience.

Hopefully the wise men will be along to pour scorn on my theory. But if it stacks up at all and there is any sense in my musings where are those mileage lines, say up to 40k miles for a low mileage “safe” example and 80k for a higher mileage version where many issues may have been already dealt with, leaving the 40-60k middle mileages being the ones where the big bills are imminent.

I can answer the low mileage vs high mileage question for you, I'm more active on other more engine specific and tuning focused BMW forums so have a good overview of the failure points albeit anecdotal.

The main problem is that most of the failure points are due to component defects rather than wear and tear. You are much better off buying a 35i at 70k that's had the injectors and HPFP replaced than one at 20k that's still on the original components. The updated injector and fuel pump design seem bullet proof.
The adaptive suspension also seems to fail on the front of the car almost uniformly at 40k miles so that's another part that will need replacing if the previous owner hasn't already.

I'd say the indicator on future reliability is more likely to be the average journey length of the car. Short city trips are going to be a killer as the oil is never going to get up to temp and unless frequently changed will leave sludge deposits and cause CCV problems.
Cars that are driven sedately and spend more time in the "efficient" area of operation are going to get more carbon buildup at the intake ports as this BMW designed the engine to reburn more exhaust gas in this area of operation for the sake of emissions.

Ideally you want to buy from someone who puts miles on it and has a no expense spared attitude to maintenance. The condition of the interior is often a good indicator, scuffed and worn leather is the marker of a careless owner. Another thing I check out when buying is the tyres and oil change interval. 4 matching premium tyres and oil changes more frequent than the bare minimum service interval are also very strong indicators for a good car.

 

[R60BBA]

Not a fan of 4 pots.

For me it would be the N52B30 in E85/86 or N54B30 in an E89 due to weight.

If you can stretch, the best concoction would be the S54B32 in an E86.

 

[abar121]

The 6 pot petrols make the car!

There's very little different in MPG and the mag block N52 is a sublime engine.

Given how much the E89 weighs and how light the six pots / front mid mounted, handling differences are a non-issue.

The iron block S54 has much more of an effect, especially given the lighter weight of a the E85 chassis. But that car is utterly dominated by the wonderful engine, so part of the charm for some, including me

 

[Silverstar]

The 6 pot petrols make the car!

There's very little different in MPG and the mag block N52 is a sublime engine.

Given how much the E89 weighs and how light the six pots / front mid mounted, handling differences are a non-issue.

+1 Exactly! When you are driving around with the hood down what do you want to be listening to? a glorious 6 or not so glorious 4?

 

[Mr Tidy]

I've always thought that the straight 6 engines were one of the Z4s unique features, so I really wouldn't want a 2 litre E85!

While I know the 2 litre turbos in the E89 can produce similar performance to a 6 I'm really not a fan of turbocharged engines.

I always loved the looks of the E86, which is handy because it narrowed my choice down to an N52 or an S54 - and both are special in their own way.

 

[Smartbear]

I've always thought that the straight 6 engines were one of the Z4s unique features, so I really wouldn't want a 2 litre E85!

While I know the 2 litre turbos in the E89 can produce greater performance to a 6 I'm really not a fan of turbocharged engines.

I always loved the looks of the E86, which is handy because it narrowed my choice down to an N52 or an S54 - and both are special in their own way.

There, I’ve fixed that for you - no need to thank me
Rob

 

[Mr Tidy]

There, I’ve fixed that for you - no need to thank me
Rob

Get back to me when you have a 4-pot that reliably gives more performance than an S54. :lol:

Iain.