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-   -   Mister Towed's SWB 250GT SEFAC build. (http://www.madabout-kitcars.com/forum/showthread.php?t=5343)

Mister Towed 25th March 2015 18:58

Took the opportunity to test drive a Z3 today, the first BMW of any kind I've ever driven.

It was a 2 litre straight six with low miles (74k) on a 'V' plate and in pretty good condition.

I was looking forward to the drive as I've only heard good things about the BMW M52 six (unlike the M44). :hungry:

So, imagine an engine that starts on the button and settles to an offbeat idle that hints at great things to come.

Imagine an engine that picks up revs quickly and smoothly, with a distinctive bass tone at low revs that builds to a spine tingling and addictive turbine whine as you keep the throttle pressed to the floor.

Imagine an engine that's docile in traffic but comes on the cams at 3,000 revs, unleashing the latent beast within and charging past the red line with no rev limiter cutting in to spoil the fun even if you keep it planted.

Imagine that's the BMW M52 2.0?

Err, no. Actually I was describing the 1.2 triple in my wife's Nissan Note, which has a hell of a lot more character than the BMW six. No, really it does despite the lack of outright power. Our Zanussi washing machine has more character on a fast spin for Christ's sake.

The truth is I found the Z3 to be enormously competent.

The engine is so quiet and smooth that I kept hitting the rev limiter in second (at a lowly 6,500rpm). The power delivery is completely linear - there's no surge anywhere in the rev range, it just pushed the car along. The suspension soaked up the bumps without transmitting the slightest of jolts into the cockpit. The steering made the car go wherever I decided to point it and the car moved along the road at speed with no drama whatsoever.

So BMW. Where's the fun? Isn't it supposed to be a sports car, not a luxury executive saloon?

Where's the mechanical thrashings of the engine? The rasping exhaust note? The steering feedback? The turn in? Where's the ability to adjust the car's attitude mid bend with the throttle? Where's the drama?

Truth be told it's a very good car, but that's damning with faint praise as I'd heard that BMW are supposed to make great cars. :ohwell:

So, what to do? Well, I still need to drive a 1.9 in case that engine actually has more (some?) character, and I also want to drive a 2.2 and a 2.8 before committing to purchasing a donor (the 3.0's brakes are too big for my wheels).

But it's not all bad news. I'm guessing a change of exhaust would make it sound more dramatic, while skinnier, taller tyres should give the handling a lot more adjustability (I was worried that the 2.0 engine would be too powerful for 185/15's but I now know they'd be fine).

Ultimately I expect the transformation from Z3 to SWB to also transform the feel of the car enough to make it interesting, while preserving enough of the sheer competence of the BMW donor to make it a genuinely capable intercontinental GT car.

Which is exactly what I didn't know I wanted until today... :bounce:

y cymro 25th March 2015 19:42

Try a 2.8 on a wet road with the traction control switched off if you want character. Look for one with Chinese tyres for additional thrills.

Mister Towed 25th March 2015 19:53

Quote:

Originally Posted by y cymro (Post 64896)
Try a 2.8 on a wet road with the traction control switched off if you want character. Look for one with Chinese tyres for additional thrills.

I'll give it a go. My, those Linglong tyres look like good value... :rip:

GazDavies 25th March 2015 20:04

I felt the same when I first got the Z3 and that is a 2.8. I was very underwhelmed however I went for it anyway as I want to build a SWB.

After living with it for a short while it has slowly changed my mind, quite possibly because I'm learning how to drive it in a way that avoids some of its quirks. Just this morning it put a big smile on my face as the traction control was kicking in to keep the rear end in check as I put my boot down on a long bend on a damp road.

WorldClassAccident 25th March 2015 20:18

MrTowed, the competence you describe is exactly the disappointment I had with the Audi A8. Extremely adequate.

I am happy to let you have a blast in mine if you are at Stoneligh.

The BMW feels far less normalised than my Merc but far more than my Nissan Navarra. I guess what you start with as a base line determines how you feel about the alternative.

See you at Stoneliegh?

garyh 25th March 2015 20:47

T, I think there's a job for you at the BBC, but instead of building a SWB it would have to be a Transit/hovercraft or some other crap.

Mister Towed 25th March 2015 21:16

Quote:

Originally Posted by garyh (Post 64907)
T, I think there's a job for you at the BBC, but instead of building a SWB it would have to be a Transit/hovercraft or some other crap.

Ha ha, I pity whoever does get that job. Mr C was Top Gear and I think the BBC have made a big, money losing mistake in sacking him.

The most annoying thing to me is that because he's lost his temper and thumped someone the beeb now can't see any way he can continue working in the public eye.

If he'd been a premiership footballer and he'd thumped/bitten/kicked/stamped on/raped someone, he'd get suspended for a couple of matches, fined twenty minutes' pay and be back on the pitch in time for the cup final.

Bloody hypocrisy I say.

Top Gear just won't be the same again and if they put Tiff Needel or Quentin bloody Wilson in as presenters I'm cancelling my TV licence as my telly will be all smashed. By me. :twitch:

Mister Towed 25th March 2015 21:18

Quote:

Originally Posted by WorldClassAccident (Post 64902)
MrTowed, the competence you describe is exactly the disappointment I had with the Audi A8. Extremely adequate.

I am happy to let you have a blast in mine if you are at Stoneligh.

The BMW feels far less normalised than my Merc but far more than my Nissan Navarra. I guess what you start with as a base line determines how you feel about the alternative.

See you at Stoneliegh?

Yep, that sums it up nicely - extreme adequacy.

Would love to meet up at Stoneleigh, I should be going this year unless work gets in the way.

Scottie22 25th March 2015 22:06

Agree with you there Mr T,

The Beeb sacking Mr C was kind of like self-harming I think.......

mobilerobbie 26th March 2015 06:04

Z-3 driving experience....
 
Mr Towed:

Do as i do, buy yourself a 3.2M Roadster and convert THAT into a 250SWB.
Put 17 inch Wires on and it's a real SUPERCAR....

Want to be sensible? no for no less then a 2.8, loads of torque and enough horses.

Both are being build right now simultanuously and will be finished in a few weeks time.....

Rob

Mistrale 26th March 2015 07:17

I have just changed back to summer tyres on my BMW 125 coupe. Winters are 16" 55 profile and summers are 17" 45 run flats. It is like driving 2 different cars. The summer tyres make it grippy, agile and lithe whereas the winters make it feel much more old school, a bit less immediate but you can 'feel' the tyres working in the corners. So there's hope yet! Mine has a 3 litre six in it but with the twin VANOS variable timing - it's nut a noticeable surge like say a Civic VTEC, but you can feel when the cams change. And I love the subtle noise that gains an edge in 'sport' mode (not sure why though!).

y cymro 26th March 2015 07:31

Quote:

Originally Posted by Mistrale (Post 64927)
And I love the subtle noise that gains an edge in 'sport' mode (not sure why though!).

Probably a pneumatic valve that opens in the back exhaust box to allow freer gas flow and a little more noise. Take a look underneath and you'll see it near the tailpipes, on mine it's gold-coloured and looks like a waste gate actuator.

y cymro 26th March 2015 07:33

Quote:

Originally Posted by mobilerobbie (Post 64924)
Mr Towed:

Do as i do, buy yourself a 3.2M Roadster and convert THAT into a 250SWB

Anyone know of a Cat C/D, vandalised or tatty Z3M for sale at a reasonable price?

garyh 26th March 2015 07:52

A programme about cars... It will never take off, you need a floating transit or caravan banger racing...

Mister Towed 26th March 2015 18:06

Quote:

Originally Posted by mobilerobbie (Post 64924)
Mr Towed:

Do as i do, buy yourself a 3.2M Roadster and convert THAT into a 250SWB.
Put 17 inch Wires on and it's a real SUPERCAR....

Want to be sensible? no for no less then a 2.8, loads of torque and enough horses.

Both are being build right now simultanuously and will be finished in a few weeks time.....

Rob

Those sound very interesting Rob, please keep us updated with progress and pictures. :)

redratbike 26th March 2015 18:10

Quote:

Originally Posted by Mister Towed (Post 64944)
Those sound very interesting Rob, please keep us updated with progress and pictures. :)

Yes please post up as many photos as possible

Mister Towed 26th March 2015 19:25

And if you need a thread to hijack feel free to use this one. I'm not that precious about it being my page. :)

8 Valve Ed 26th March 2015 20:44

Tyre ratings
 
Mister Towed, in another thread:

http://www.madabout-kitcars.com/foru...postcount=1006

You gave some very helpful advice about tyre choices which is simply presented and to the point.

However, what do we do if there isn't an 'official' specification? Suitable for the purpose... How long is a piece of string.

My Marlin Berlinetta was 'available' in two broad specifications, 2 litre Ford Cortina with Cortina suspension, brakes etc., or Rover V8 3500cc, same suspension (wheels and tyres?) and brakes in both cases.

While the car is obviously more powerful in the V8 spec, I can not find any guidance in my build manual about the correct tyre sizes or ratings for either spec.

My simplistic logic suggests because the car is lighter, the amount of power and stress on the tyres will be less, even allowing for the fact that the V8 engine is more powerful. The original Cortina was just short of 1000Kg, a tad more with up to 5 occupants. The Rover SD1 V8 around 1,250Kg + up to 5 occupants. I estimate the Marlin will be 750-800Kg + 2 occupants, significantly lighter.

Where do I (and many other Kit car users) stand? The car was built in 1985, so a lot has changed in the sense of risk assessment and applied regulations. I suspect most of the Kit Cars of that era were designed on the back of a fag packet and in chalk on the works floor, Perhaps they still are???

My MOT garage takes the view that given most kit Cars are self build, provided they are well assembled, well maintained and not obviously dangerous, they are OK. Their standpoint is they are not qualified to state what specification should apply. They tend to apply the old maxim that if they would be prepared to use the car themselves, it should pass.

My own feeling is that using 185HR 14 or 205HR 15 tyres should be a reasonable choice, because the original Rover V8's were fitted with the 185HR 14 tyres.

Mister Towed 27th March 2015 06:29

Hi Ed, the thread where the tyre speed rating was being discussed is for a car where the modern donor can run up to a (limited?) 155mph top speed, and people are already talking about turbos and superchargers.

Obviously, the performance potential of those cars plus the easy access to information about the donor vehicle makes it easy for a collision investigator to check whether the tyres fitted are correct for the car.

Where 'classic' based kit cars are concerned there are two factors at play - one is that the data isn't available off the shelf to check, and the second is that pretty much nothing that got used as a donor back in the day could exceed 120mph anyway.

I'd say that a Rover V8 Marlin (with about 150bhp?) would, depending on the gearing, be all done aerodynamically by about 110mph, and more power wouldn't necessarily add much to the top speed, just the acceleration. As such, you could put hand on heart in Court and state that the H rated tyres you fitted were definitely suitable for that vehicle.

The current BMW based Marlin Sportster, however, would quite possibly need V, W, Y or Z rated tyres.

As for availability, generally speaking, kits using older donors (Sammio/Miglia) use classic wheels and classic tyres are available to suit, while more modern donors (Z3/MX5) tend to use modern wheels and modern tyres are also available to suit.

After two years driving my Spyder on modern roads my advice would just be 'don't skimp on safety'.

8 Valve Ed 27th March 2015 09:33

Thank you for your input Mr T, It's nice to have one's own thoughts confirmed. These days things don't always seem to follow conventional logic!

The only reason I have gone with the Rover V8 is for grunt, we have lot's of big hills around here; also the ability to pull a reasonably tall 5th gear at 70 on the motorway for effortless cruising and hopefully, reasonable economy given the engine size. I have no interest in high speed or racing but possibly the occasional classic endurance trial.


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