Re-mapped N20 engines

[Anonymous]

Hi yes I have the H&R ARBs front and rear fitted on the middle position on the rear..no fouling but I running stock springs, fouling seems to be associated with lowered suspension..the only issue is that the shouldered bolt on the rear arb wouldn’t fit without severe distortion of the bush. I sourced a shouldered bolt that was about 4mm less shoulder.

You have to fit a matched pair of arbs or ‘bad things happen’ mid corner in a bump..

Works very well , a little bump steer with a really big bump mid corner but compared to OE set up big improvement..

I fitted the B8 shocks at the same time do can’t see how much of the improvement came from each part.

Net result is very good handling, little toll if any but still very comfortable ride with just a small amount of jitter on rippled roads at sub 25 mpg speeds

 

[lewis1962]

Enjoying reading this, I'm looking at going the next stage. I had a Stage 1 done at the same place as Peter and am now looking at buying the VRSF downpipe. Would it be worth changing plugs and coils before the next map. Would a cooler plug be suitable ? Let me know your recommendations, as i'm a novice at this

 

[Anonymous]

Enjoying reading this, I'm looking at going the next stage. I had a Stage 1 done at the same place as Peter and am now looking at buying the VRSF downpipe. Would it be worth changing plugs and coils before the next map. Would a cooler plug be suitable ? Let me know your recommendations, as i'm a novice at this

z4 28i auto stg1.png

Hi, IMHO the plug n coil change seems to be of limited value on the N20 engine.

In contrast to the N54 engine in the 35i this engine was re-designed so it doesn’t tend to overheat / cook bits..

I’d probably change the plugs with NGK standard heat range, if you want belt n braces them do the coils...again NGK is a good choice.

I would recommend getting the bits from a bona fide supplier such as AutoDoc rather than risk a no name eBay supplier as there are many boughs parts...plus a new Mahle OE air filter ..

I would change the oil and get a premium ester based oil..such as redline or Fuchs and if this is with a de-cat go for a 10-40 or if nota ‘euro spec’ 5-30 plus again Mahle oil filter ...the boys in Sunderland can do all that as a job prior to a new setup / dyno run..

 

[lewis1962]

Cheers, I've sent them an email, got to keep modding in 2021 !

 

[MACK]

Hi yes I have the H&R ARBs front and rear fitted on the middle position on the rear..no fouling but I running stock springs, fouling seems to be associated with lowered suspension..the only issue is that the shouldered bolt on the rear arb wouldn’t fit without severe distortion of the bush. I sourced a shouldered bolt that was about 4mm less shoulder.

You have to fit a matched pair of arbs or ‘bad things happen’ mid corner in a bump..

Works very well , a little bump steer with a really big bump mid corner but compared to OE set up big improvement..

I fitted the B8 shocks at the same time do can’t see how much of the improvement came from each part.

Net result is very good handling, little toll if any but still very comfortable ride with just a small amount of jitter on rippled roads at sub 25 mpg speeds

Do agree about matching pairs to avoid inducing under/oversteer.
But it does get slightly muddy when it comes to the E89. Unlike the E85 which varied the size of the ARB's on the standard models dependent on trim level and engine size. With H&R offering a kit that then takes the ARB's further, up to the same sizes on the Z4M models. On the E89 it's obvious that outright handling wasn't BMW's priority with all models regardless of trim or engine size having FRONT 26.5MM and REAR 19MM.

Aftermarket wise there's two options on the E89, Eibach and H&R with both having a rear bar 21MM so an increase of cross sectional area of 22.25% over standard. This does make sense to me as I perceive most of the excess roll in the car coming from the lardy rear, especially when the heavy roof's stowed away.

Its the front where things get tricky. H&R offer 27mm which is only an increase of 3.8% which I'm really not sure would be noticable, but maybe I'm wrong. Eibach offer 28mm which is a healthly increase of 11.5% which I'm sure is noticeable. The dilemma for me is which way to jump. Especially with mine being a lighter 4 pot lump. I'm really not sure if the 28mm might actually be overkill, the 27mm just right and a decent improvement over standard or it will give such a small imperceptible difference I might as well stick with 26.5mm standard on the front, especially on the 4pot.

First World Problems with too much time on my hands!

 

[Anonymous]

Hi...I didn’t realise you could just buy a front or rear separately...I can’t remember when I ordered the H&R if that was an option..I can’t recall it.

Well you have been studying the details

Certainly on the back for use on the roads that I frequent I wouldn’t want any more bump steer from the back.

With Eibach springs (you need to work out the travel / progressive spring rates , if they are progressive :rofl: ) I would imagine they will add to the bump steer and then you get more of a ‘jiggly’ rear end.. :tumbleweed:

If I could be bothered I could put the H&R rear on its softer setting and see but can’t see it’s going to yield any benefit..the bump steer I do get at the moment is only under pretty severe conditions that would have many cars ‘boinging’ into the undergrowth..

Certainly hooning with a variety of E85/E86/Ms the general comment from them is that I can go round any corner at least as well as them plus a much better ride in almost all conditions..so overall much faster for the same level of comfort..

As far as the front is concerned there is no obvious negative traits..it simply goes round corners very well save severe bumps at high speeds where there is the vaguest of ‘getting wobbly’ from the front..not sure whether it’s the springs too soft but again compared to where it started very different...

I know the 6 cylinder guys and especially the 35 clan get animated but compared to the 30 and especially the 35 the weight on the nose is markedly different so I’d be surprised if you found the uprated roll bars inadequate..certainly the chap in the US morelli who did some very heavy modding to a 35is found that the H&R were up to the job.

It’s complex with so many variables interacting wheel sizes/tyre sizes/tyre choice/offsets/ARBs/springs/dampers and in my case M3 steering/suspension parts and Quaife LSD

Certainly for me it’s reached the limits that I can understand/explore..with the engine mods it’s a well matched combo.. :driving:

Sorry for waffling..as you say 1st world issues.. :rofl: