limets of the chassis

[madmax]

what are the limitations of the chassis i.e how much power and torque will it take in standard form.

[Talonmotorsport]

One limit would be that it does'nt fly! I can not see why you would want to put too much power in some thing that does'nt weigh alot maybe 550-700kg max. As the chassis is only light I would have thought that it twists as you drive it, espeshily if your running any thing over 250lbs springs.
Much more than a 200bhp NA 4 pot or even mild V8 and you'll end up shreading the tyres in the dry or it being a pig to drive in the wet.
Unless of course your using it for drifting then put in welded steel floor,up the box section to 2mm,reinforce the rear diff mounts and suspension abit and add a full rollcage. That I can do for about £1800
What colour do you want it?

[mr henderson]

Another thing to bear in mind is that unless the power/torque can be successfully transferred to the road, then it is irrelevant just how much there is of it. Thiat is because for the chassis to be subjected to twisting forces there has to be a matching load. No load (for instance, spinning tyres) no twisting force.

Consider a tow rope. Is it strong enough to be used with a supercharged 8 litre LandRover? The question is meaningless until you know how heavy the LOAD is. The load on the powertrain of a car depends on how much grip (traction) there is, and the mass of the vehicle. Sevens don't have very much grip because they don't weigh very much.

[ACE HIGH]

Using commonsense about 120/150 hp,180 hp maximum,if you want to use higher power use 32x32 x1.6 or larger.Take a look at the Brunton 7 Stalker USA.These space frames are not as strong as everyone thinks,in fact a simple ladder chassis as used in typical US rods is stronger and once cross braced much stronger.Also 120 hp will easily do 0 to100 in under 6 seconds.I believe the limitations of clubman 7 cars is the old fashioned diff (sprung/unsprung weight)but the independent rear suspension of the Haynes Roadster will lift the clubman 7 roadholding to a new level.:) David

[mr henderson]

Using commonsense about 120/150 hp,180 hp maximum,if you want to use higher power use 32x32 x1.6 or larger.

Why does using higher power mean that you need thicker steel? "Commonsense" is a bit vague.

There are all sorts of spaceframe kit cars out there, many of them by established manufacturers such as Caterham, Westfield and Dax running power units of well over 200bhp, in some cases more that 300bhp in totally standard chassis without problem.

[RAYLEE29]

look at the superlight r500 263bhp 177 llb ft torque
isnt that enough for anyone
Ray:)

[madmax]

thanks for all the info i will be thinking about that for a day or two don't think i will be putting more than 300bhp in turbo form in the chassis

[deezee]

what are the limitations of the chassis i.e how much power and torque will it take in standard form.

This is a pretty silly question. For a start if your going over 200 bhp your going to need a different gearbox (chassis redesign) or a couple of thousand quid for a uprated type 9. You might even be using an alternative diff / subframe if your talking big power. So if your going to be fitting a new drive train, complete with all the modifications it requires, surely adding some additional strength won't be a problem for you.

Then after all this, you'll need to fit new brakes to stop the awesome power and a rollcage for when you leave the tarmac to go and modify a tree.

[Beardy_John]

look at the superlight r500 263bhp 177 llb ft torque
isnt that enough for anyone
Ray:)

Your right about the figures, they are awesome for a 7 style space frame, but have you looked at any pictures of that space frame?? Its very impressive and very well triangulated in a lot of directions, and probably a bit too much to re-create for the average locoster. Unless they've got a tube lazer:eek:

[RAYLEE29]

yes agreed but the point I was trying to make you dont need to have stupid power for loads of performance and fun.
Ray:)

[ACE HIGH]

Commonsense means that Colin Chapman's original 7 started off with less than 40 HP and during his lifetime reached around 125hp with the twin cam.Yachts and power boats have a hull displacement speed which is not easy to excede no matter how much power or sail area is applied to the boat.So it is with a Clubman 7,As the style of the car has to remain basically unchanged then the limiting factor is the aerodynamics which is about the worst on the road,and no amount of HP after about 150/180 is going to do much good as the steering gets a bit light from 140km on and approaching 180km plus then a certain amount of danger is present.The Clubman 7 has a few failings which would be better to spend time and money on,namely,the butt ugly exhaust that exits by the drivers ear sending exhaust gases into the cockpit,the 45 degree coil over shocks that give a bad uncomfortable ride,it really needs torsion bars all round with vertical shocks,or perhaps Mcpherson struts at the rear.For ultimate performance it seems that a motorcycle engine is the best idea,has anyone thought of a big 1340/1500 cc Harley?that would give a very good engine to use once cooling was worked out and a high torque Harley around 85 hp plus,unstressed with a lightweight Roadster would be better performing than some of the big engined vehicles.Lightweight is the way to go in my opinion.That should get you all going,stir/stir!!!David:p

[ACE HIGH]

Also if it was possible to put inboard rear brakes on the Roadster this would be an improvement worth more than a heap of horsepower.David

[deezee]

the butt ugly exhaust that exits by the drivers ear sending exhaust gases into the cockpit

LOL or just get a nice Zetec or other engine that has the exhaust on the correct side :rolleyes: Just my opinion, but I like side exhausts on a car :D You make it sound like you hate the car, with its ugly looks, awful comfort, poor handling and dangerous steering:confused:

[mr henderson]

Commonsense means that Colin Chapman's original 7 started off with less than 40 HP and during his lifetime reached around 125hp with the twin cam.Yachts and power boats have a hull displacement speed which is not easy to excede no matter how much power or sail area is applied to the boat.So it is with a Clubman 7,As the style of the car has to remain basically unchanged then the limiting factor is the aerodynamics which is about the worst on the road,and no amount of HP after about 150/180 is going to do much good as the steering gets a bit light from 140km on and approaching 180km plus then a certain amount of danger is present.The Clubman 7 has a few failings which would be better to spend time and money on,namely,the butt ugly exhaust that exits by the drivers ear sending exhaust gases into the cockpit,the 45 degree coil over shocks that give a bad uncomfortable ride,it really needs torsion bars all round with vertical shocks,or perhaps Mcpherson struts at the rear.For ultimate performance it seems that a motorcycle engine is the best idea,has anyone thought of a big 1340/1500 cc Harley?that would give a very good engine to use once cooling was worked out and a high torque Harley around 85 hp plus,unstressed with a lightweight Roadster would be better performing than some of the big engined vehicles.Lightweight is the way to go in my opinion.That should get you all going,stir/stir!!!David:p

You don't seem to have addressed my question about why you felt that commonsense dictated a chassis made from thicker steel at higher horsepower levels, "Using commonsense about 120/150 hp,180 hp maximum,if you want to use higher power use 32x32 x1.6 or larger.". Do I take it that you have now dropped that?

If wanting to use a strut suspension at the rear, it would be better to use the Chapman strut, such as was originally used on the Lotus Elan. That, combined with the inboard brakes you suggest, would certainly reduce the rear unsprung weight.

[fabbyglass]

Better to have the car set up so it handles and stops well with 100 ish bhp to make things fun rather than scary, what use is not being able to stamp on the pedal for fear of spinning as too much power...:D

[Bonzo]

Ohhhh............... I do love a good debate, some have said that I am a master debater, or at least I think that's what was said !!?? :D

Many of you may well be aware that it took me over a year to decide on what engine/power to use :rolleyes:

Now I like to read a lot, I am also willing to learn from those who are more qualified than me.

My chioce was made after a long discussion with a former, competition racer of the 7 type chassis.
The same guy also runs a sucsessful engine & car performance company.

He is of the view that a well tuned 150 BHP engine is about the right power for the 7 type chassis.
His words were " If you are looking for a lot more power, choose a diffent chassis " . His view on what to do if you actually want to make full use of the power available.

My point !!??

Although I don't doubt for one moment that the Roadster chassis would be unable to cope with massive amounts of horsepower & torque.

How are you going to be able to get all of that power onto the road & make full use of it :confused:

Reworked chassis & mid engine per chance !!??

The boat example puts over a point nicely. My yorkshire Cobble went just as well with a 6HP motor as it did when fitted with a 15HP one ;)

[Balidey]

I think the law of diminishing returns is appropriate here.
Car with 100hp is not half as fast as one with 200hp.
And going back to the original question, does a more powerful engine require a stronger, thicker chassis? Well it depends, if the engine is going to try and twist the chassis then yes. But the fact that the chassis just holds the bits together, then it doesn't matter how powerful the engine is. Using a 45hp engine doesn't mean you can get away with a chassis made of balsa wood.

And some of this boils down to Pub Talk. :D My good friend wanted a kit car and at the time he didn't know what he wanted, so we talked about engines and chassis types. In the end he went for a Viento (the biggest) he went for a Rover V8 (massive engine) but then went to a 4.2 semi race tuned engine with huge carbs. Massive 17" alloys with low pro tyres. All parts of the car were 'bigger and better' and to me it lost its appeal. I want a small, light 7. Not a huge bling car. (Mark, if you read this, I'm sorry, I don't mean it :p ).

And I think this mentality is still here, if someone thinks 150hp is enough for a 7 then the next person says 'well I'm having 200hp' and then the next say 'well I'm going for 250hp' then the next says.... well I think you get my drift.

[fabbyglass]

Keep it simple keep it small and enjoy it more, the more you spend the less likely you are to play properly

[HandyAndy]

Keep it simple keep it small and enjoy it more, the more you spend the less likely you are to play properly

sounds about right for me :D

my £3k car with the 1.8cvh = approx 90 - 100 bhp ;)

tho the words of a forum member with a completed car still sound in my ear " you,ll want more power eventually" :D

andy

[fabbyglass]

Bike motor time then Andy....not mega fast but it's how they get there that will have you giggling yer head off.

[HandyAndy]

Bike motor time then Andy....not mega fast but it's how they get there that will have you giggling yer head off.

;) that,ll be for the single seater :D
as you know my biking background, i,m sure i,ll want that "rush" of instant power ;) :D

andy

[ACE HIGH]

No deezee I love the car,over 40 years ago I wanted one,could not afford one,they were expensive in those days,so bought a TR3A instead,25 years later I bought a Chevron 7(NZ 7,)wonderful car but it had some faults that needed correcting,the same faults as the original clubman 7 cars and the same faults as today's ones,I feel that too much attention is spent on how many HP and not enough on improving the comfort a bit,eg "the board like ride",I intend to build myself another in due course and improve a few points,eg I feel that power steering from the donor is worth putting in.The Chapman strut idea of Mr Henderson's is a good one,but I dont know where one would be able to buy them.The coil overs are a horrendous price also.Now back to the chassis,over 40 years as a fitter/welder gives me a "gut feeling" that the chassis is not strong enough for over 150 hp,the Brunton Stalker (USA)uses 40x40x1.6 I think with 200/300 hp of 3.8L V6 Chevrolet.32 mm or more will not weigh much extra.I have repaired enough fatigue cracks etc to trust my instincts on this in spite of whatever Caterham etc do.Also sorry guys but this will get you going!too many of the welds and fitting are not up to standard ( Caterhams would be) and the riveting of panels ad lib means in many cases these vehicles will rust from the inside out.Think about it.Its also good on these forums to get some different views and ":)lateral thinking":) David