My VortX R1 (4XV) ended up being around 600kg wet and with me in it...

Two up it still goes well, but you can definitely feel another person on board.

As a few may be able to tell (sorry about all the posts!) I'm scoping out my new project, which needs to include a roof, heater, doors, a reverse and the ability to sit at 80mph ish and not make my ears bleed (i.e. still be a able to hear the radio...).

So I've been looking at cars that I like the look of (in a weird way...) and I've been looking at iQs (850kg ish), BMW Mini (1100kg lightened significantly), and even things like BMW Z4s and Audi TTs (1200kgs, best bet).







I am set on using a Kawasaki ZZR1400 motor (which I will NOS later in its life), but I really want to know if anyone's got a 'feel' for the maximum weight a BEC should be to still feel quick...

I'm arbitrarily saying 1000kg... Thoughts / experiences?!

Ta in advance.

Chris.

[Edited on 14-4-19 by Winston Todge]

Its not the power that is the issue with bike engines it is the lower levels of torque and torque is what you need to accelerate the mass of the car.

<pedant mode on> I assume you live in Germany and it is for “sitting at 80mph” on the autobahn and not the U.K.<pedant mode off>

Have you had a look at the classic mini r1 conversions, looks like the ideal solution. These modify the front subframe to accept the r1 engine, bolt it in and use the bike wiring and off you go, just add an electric reverse.

For the zzr1400 I would have said 750kg would be max giving you 266bhp/ton but as said the lower levels of torque may not make it feel as quick off the line and I think you will need a well packed exhaust (which may reduce power) and need to do something about induction noise if you are to make it cruise quietly.

Also, if this is a road car (unmodified shell etc. so no Iva) are how are you going to deal with emissions at mot with the bike engine as they have different rules iirc and don’t tend to use a cat. (Happy to be corrected).

Had a quick look at the torque curve of a zzr1400, there is 80% of the peak torque available from 5500-10500rpm.
Red line just over 11000rpm.

So at around 80mph, you probably still looking at 6-7k rpm. But in top gear that would give you 140mph top speed.
The clutch strength might be the otherr side of the story as well.

A Mini with R1 will be a bit below 600kg.

You could stick a turbo on it, more torque and more muffling...

GAAAAAAAAAHHHHHHHH!

Do you lot never listen/pay attention to anything at all???

The whole BEC's have no torque is complete & utter bollox unless you are talking about something like the original 893 'blade or similar, modern larger capacity engines are a whole different kettle of fish

The Furore weighs 565kgs with the ZZR1400. I weigh around 70kg, so we're up to around 635kg, adding an extra person, & I've had some fairly large passengers over the years, several who'd weigh 100kg+, the difference in performance is barely noticeable, the only significant difference is that on a hot dry day with sticky tyres it makes it difficult to spin the rear wheels - even then 0-60 performance is still well under 4 seconds

I run a fairly high diff ratio, 3.28:1 & 17" rims with not particularly low profile tyres - the result is 70mph at 4750rpm, this is not stressful in the least & if the engine is behind you & behind a proper bulkhead with a bit of sound proofing you're hardly gonna know it's there! Someone has already pointed out the torque curve is relatively flat & max power is at a relatively low 9,500 (it revs to 11,500) so there's no need to scream the knackers off it to get performance

Why does it have so much torque? ALL bike engines have a reduction gear b4 the gearbox, typically around 1.5/1.6:1. The stated torque is 113 ft/lbs, but that is at the flywheel - the torque which is actually usable & reaching your gearbox is around 180/ft/lbs

If anyone disbelieves me, just pop round & I'll take you for a run, you will never, ever suggest again that BEC's lack torque (make sure you bring a change of underwear!)

Re emissions/CAT's etc. I've never had any significant problem at IVA, just tweak the map a little with Power Commander. The 2016 on ZZR's have a small CAT built into the front pipe, no idea if this would be adequate to pass a BET's test tho' I simply added my usual IVA exhaust for the only 2016 one I tested

quote:

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Originally posted by russbost
GAAAAAAAAAHHHHHHHH!

Do you lot never listen/pay attention to anything at all???

The whole BEC's have no torque is complete & utter bollox unless you are talking about something like the original 893 'blade or similar, modern larger capacity engines are a whole different kettle of fish

The Furore weighs 565kgs with the ZZR1400. I weigh around 70kg, so we're up to around 635kg, adding an extra person, & I've had some fairly large passengers over the years, several who'd weigh 100kg+, the difference in performance is barely noticeable, the only significant difference is that on a hot dry day with sticky tyres it makes it difficult to spin the rear wheels - even then 0-60 performance is still well under 4 seconds

I run a fairly high diff ratio, 3.28:1 & 17" rims with not particularly low profile tyres - the result is 70mph at 4750rpm, this is not stressful in the least & if the engine is behind you & behind a proper bulkhead with a bit of sound proofing you're hardly gonna know it's there! Someone has already pointed out the torque curve is relatively flat & max power is at a relatively low 9,500 (it revs to 11,500) so there's no need to scream the knackers off it to get performance

Why does it have so much torque? ALL bike engines have a reduction gear b4 the gearbox, typically around 1.5/1.6:1. The stated torque is 113 ft/lbs, but that is at the flywheel - the torque which is actually usable & reaching your gearbox is around 180/ft/lbs

If anyone disbelieves me, just pop round & I'll take you for a run, you will never, ever suggest again that BEC's lack torque (make sure you bring a change of underwear!)

Re emissions/CAT's etc. I've never had any significant problem at IVA, just tweak the map a little with Power Commander. The 2016 on ZZR's have a small CAT built into the front pipe, no idea if this would be adequate to pass a BET's test tho' I simply added my usual IVA exhaust for the only 2016 one I tested

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Just came here to post the same as the above!

Modern 'Blades have about a 1.72 reduction in the gearbox, so your 80-90ftlbs (more torque in a car because of the exhaust, providing it's well built...) becomes a bloody good chunk of torque at the prop, as has been said.

I did some calcs for this recently, hopefully the annotation on the graphs says it all...



Weight I used for the CEC was 600kg all up, BEC 500kg all up. Same size wheels / tyres.

To put a practical case to it... 70mph cruising in top gear - just over half revs in both the CEC and BEC in this comparison, around where each engine will make maximum torque. Plant your foot and the BEC sends 761Nm to the rear hubs, the 4 speed CEC 825Nm and the 5 speed 718Nm. Add in the weight factor, and the BEC is putting a good chunk more torque per ton to the road.

So back to the original question... I don't think it really matters, but lighter the better!

[Edited on 15/4/19 by AdamR20]

[Edited on 15/4/19 by AdamR20]

Absolutely awesome input peeps! Really appreciate it...

I was starting to get a little pessimistic about the aim I have in the next project. You've all helped out a load!

I forgot to mention one important constraint... That is has to be RWD and rear engined if possible, so I can use one of Doug's beautiful Westgarage chain LSD diffs (to minimise the 'slop in the transmission' that I just cannot get rid of when driving a front engined VortX and a TRT / Sierra diff combo...).

Really starting to think a slightly larger RWD car would be easier / safer to convert in the long run, but then where's the fun in that...

I'm starting to look at a severely lightened Audi TT as the rear end already has an LSD in it and a ZZR1400 engine would fit in there where the rear seats are without stacking the engine above the diff (keeping the CoG low).

THANKS ALL!

Chris.

That sounds like a heck of a project. Let us know when the build thread starts

The world's first 13000rpm hairdresser


[Edited on 15/4/19 by AdamR20]

I've just got to finish the garage (properly sorting it this time...).

Duramat floor laid completely rewired, walls painted, 8 new LED bar lights fitted and just re-organising the Fireblade, MNR and lawnmower to get the project car in position.

Thinking about a two post lift too, but think the wife may put the kaibosh on that one.

I'll lob all the build status up as and when I make some decisions / progress.

Not sure whether to get the donor bike first and strip and sell on the parts, or start with the donor car... I suppose whatever turns up first at the right price.

Ta,

C.

Would a Smart Roadster/ Coupe not be an idea?



http://www.extreme-engineeringuk.com/the-story.html

[Edited on 15/4/19 by ettore bugatti]

Re the length/packaging issue, don't forget the rear wheels don't need to be inline with the diff, you can run driveshafts angled towards the front at anything up to around 30 degrees using CV's, also, you could always add a "power bulge" to the centre rear of the car to accommodate the diff.

To help keep the front/rear length of the engine & driveline as short as poss. you could fairly easily devise a different place to put the electric reverse, it could even drive one of the front wheels

On the subject of bike engine torque, I've just checked on a few rear wheel dyno charts and they all show a zzr1400 (1441cc model) with between 112ftlb and 120ftlb, just thought I'd say.

Shooter

quote:

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Originally posted by Shooter63
On the subject of bike engine torque, I've just checked on a few rear wheel dyno charts and they all show a zzr1400 (1441cc model) with between 112ftlb and 120ftlb, just thought I'd say.

Shooter

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As it was probably me who started the "torque" questions/debate - please can you enlighten me as I am a bit confused at the moment -

for a zzr1400 the dyno figures I can find at the rear wheel are approx 175hp and 115ftlb
for a 2.0l Zetec with around 175hp at the rear wheels (200ish Hp at the engine) I would expect a rear wheel torque of around 150ftlb
for a 2.0l BMW diesel with around 175hp at the rear wheels I would expect a rear wheel torque of around 230ftlb

Note all measures data at the rear wheel and not corrected to provide at engine results.

If you are measuring at the wheels on the dyno does it matter what the engine or gearbox figure is as it is the "at wheel" figure that will provide you with the best estimate of the relative performance (assuming the vehicles are all the same weight/mass and have the same tyres and power train losses) i.e. assuming the wheels do not slip - the amount of energy that can be transmitted from the tyre to the tarmac which is a measure of the torque of the engine AFAIK.

As a simple example myself and my wife had everyday cars that both had 100hp, mine was a diesel and hers was a petrol, in terms of acceleration mine was by far the quickest with the only difference being that mine has close on twice the torque (similar weight).

A supplementary questions is do the RPM have anything to do with it, the ZZR will be making max torque at say 8k and power at 12k where as the zetec would be at 4k and 7.5k respectively and the deisel 2.5k and 6k respectively.

Sorry, so many questions but I am a bit confused so if anyone can explain then that would be very useful.

Torque is measured, bhp is a 'theoretical' value that is calculated.

Torque is how hard the engine is twisting the prop, rpm tells you how many times per minute the prop is being rotated with that torque. From this you can calculate the total power output which we know as bhp.

So you can have a low torque engine that provides that torque many times a second (bike engine), or a high torque engine that does it far fewer times per second (diesel engine with a turbo), and they'll both have done the same amount of work / created the same amount of energy.

You also need to look at the area under the torque curve. This shows the total amount of work done by the engine. So your example with your N/A vs diesel turbo car, and the diesel is faster but they both put out the same bhp, it's because of the shape of the curve. Your petrol car's dyno torque plot is (simplifying) a straight line to the limiter, the diesel will have much more torque at low rpm and the shape rises up sharply at the start then is a bit of a plateau, so the area under that line is much greater and it is doing more work across the rev range.

Hope that helps a bit?

Had my 'Blade on dyno yesterday and it made 92FtLbs / 124Nm and a pretty flat torque curve. With the drop gear that's about 160FtLbs / 213Nm effective output.



(The engine has a few internal tweaks and I have been VERY anal with the exhaust manufacture, it's not a 'downhill dyno'!)

[Edited on 17/4/19 by AdamR20]

Thanks for that, got but what I don’t understand is -

If all three engines in my example are measured at the wheels where does this “drop” gear come in and why that make a bike engine measured at 115ftlb max at the wheels the same as a car engine measured at 160ftlb max at the wheels even if the bike engine is turning 1.5 times more to make what is less torque? As far as I can tell the rollers are seeing different amounts of torque being applied by the tyres so how does a gearing before the wheels make these two different measured figures the same.

[Edited on 17/4/19 by Ugg10]

quote:

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Originally posted by Ugg10
Thanks for that, got but what I don’t understand is -

If all three engines in my example are measured at the wheels where does this “drop” gear come in and why that make a bike engine measured at 115ftlb max at the wheels the same as a car engine measured at 160ftlb max at the wheels even if the bike engine is turning 1.5 times more to make what is less torque?

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Thanks for the comment RussBost, glad it is not just me :-)

I guess my experience is at the lower power end but if you take 30-60mph acceleration times (real world usability) the diesel was so much quicker than the petrol car with the same power and weight (but different torque).

My car engine rule of thumb was 200bhp/ton would give you about 6s 0-60mph. And again for a car engined seven or similar (fury etc.) I always thought the sweet spot for a road car (that was usable in most conditions) was around the 175hp (600kg car). This was enough so you could drive at 8/10's on the road and not be a danger to yourself or other people (assuming suspension, brakes and big nut behind the steering wheel are up to the job).

Personally I would expect a 500kg 200hp bike engine car on a track to be much quicker than a 800kg cobra with 400hp, maybe not in that 30-70 test but in terms of cornering speed and ability to maintain speed at a higher level and reduced braking distances etc. - Colin Chapman "added lightness - virtuous circle".

As for RPM - I think this is not an issue - if you gear two cars to the same top end, the car engine will reach that at 7k and the bike at 11k - AHHH - light bulb moment - this may be where the "reduction gear ratio" may come in - Think of lifting a weight with a pulley to a certain height you expend a certain amount of Kinetic Energy that is equal to the potential energy you are putting into the weight (mgh=1/2mv^2 iirc) so if you increase the pulley ratio you have to mover the rope quicker to raise the weight to the same height in the same amount of time - same energy expended.

So, if the bike engine is running 11k but has a lower max torque it will get to the same speed in the same amount of time as a car engine with greater torque but less RPM.

Is this correct ???

Sorry OP, this has got off topic a bit, I'll shut up now.

Don't shut up!

This is exactly the discussion I wanted!

I genuinely think that if I'm investing 3+ years on the next project I want to try to get the best steer possible to get enough momentum to actually do what I set out to do.

And all of this is really helping. It's definitely made my mind up I'm sticking a ZZR motor into something with...

1. 4 wheels
   
2. A heater
   
3. Doors
   
4. A roof
   
5. A ZZR1400 motor
   
6. A reverse gear
   
7. RWD
   

If you want do it properly, you will need to plot some graphs:
http://www.thecartech.com/subjects/auto_eng/Tractive%20Effort.htm

In theory you should be able to trade off revs to gain torque since power is the product of revs and torque.
But in practice I think torque to weight ratio is a factor to.
A BMW 323i e46 with 170hp and 1400ish kg was as quick through 3rd gear as a Lotus Elise 111s with 165hp but only dragging 900kg. The only difference is that the BMW had 245Nm which is more than the 180-190 of the Elise.
Standing start was a different story &#9786;

[Edited on 17/4/19 by ettore bugatti]

"Personally I would expect a 500kg 200hp bike engine car on a track to be much quicker than a 800kg cobra with 400hp, maybe not in that 30-70 test but in terms of cornering speed and ability to maintain speed at a higher level and reduced braking distances etc. - Colin Chapman "added lightness - virtuous circle"

All the comparisons were simply straightline acceleration, typically 30 - 70, 50 - 70/80, 50 - 100ish, I would have expected the Cob, with that amount of power & torque to win out at least some of the time & it wasn't a traction issue, warmish weather & dry roads, neither of us having an issue getting the power down. The only thing it's been beaten by in straight acceleration are 1000cc plus bikes & even then only modern ones, it was pretty much equal with an early R1. I just find the ZZR1400 a gobsmacking motor - the only downside when compared to the 'Busa is that there's very little tuning gear available for it - maybe 'cos in the bike you'd be nuts to want it (doesn't stop peeps tuning 'Busa's tho' ....)

Around blyton my 850kg v8 roadster with 450hp stays with busa powered cars pretty well reeling in any corner speed and braking advantage over the Lap . On the long straight there’s nothing in it as I’ve got to brake earlier , on the road the acceleration from 90+ my car would stride away with 400+lbft all the way from 2-6k

quote:

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Originally posted by Ugg10

Stuff

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It seems the general population think BECs are a waste of time!

Och well, I don't want my next project to be entirely based on logic...

https://www.minitorque.com/forum/f10/rwd-r53-zzr1400-engine-206335/

http://www.16vminiclub.com/showthread.php?t=38738

Just need to try to find some way of getting other ideas on what donor car rear ends are worth considering for this.

Maybe I just shouldn't mention motorbikes?!

C.

There was an DVD where somebody went through the complete process of building a Z-cars Mini should give you some pointers on the engineering bits.

I think converting a FWD shell to midengined rear wheel drive setup is probably not the way if you are really concerned about noise and comfort on the motorway.

Also the modern cars have more electronics (CAN Bus) which are more difficult to adapt integrate with the engine change. So I would steer away from most modern cars, unless you go for a wiring loom from scratch.

A GTM Libra might be another candidate to convert.