Limits of the chassis
 

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

Limits of chassis
 

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

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:

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.

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

Can I play
 

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 ;)

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.

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

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