Power To Weight

[Guest Bluey]

Anyone know what the approx weight of a Superspec with Rover 2.0 turbo is. I appreciate that to some degree it depends on what you put on it in build phase, but wanted to work out my rough ptwr

[Guest Tim Norman]

750 to 800kg depending on what you have in it

[megadodo]

My 2B with a pinto was 750kg at IVA, Superspec must be similar

[Guest Jomeo69]

I havnt cropped up in a while but here is my addition.

 

After wondering the same question for IVA i phoned GBS to ask what the weight of our superspec with a 2ltr zetec would be.

The answer frankly surprised me.

 

I know the chassis is a little on the chunky side, but they quoted me 450kgs for the front axle and 600kgs for the rear. Total 1050kgs.

 

Now i didnt question this as it was from GBS but did wonder if it was at all accurate, as the gent on the phone said that having a zetec instead of a rover engine made next to no difference to the weight apparently.

 

If anyone could shed any light on this it would be great.

 

Many Thanks

 

Joe

[richyb66]

The 1050Kg figure quoted by GBS is the figure used for the IVA test to calculate braking efficiency - it's not the actual weight, which is around the 750-800Kg that Tim mentioned.

 

Also the 450Kg figure is for the rear axle, not the front.

[Guest Jomeo69]

ok excusing the mess up with the axles, so essentially its wrong?? surely it makes more sense to calculate braking efficiency on the actual weight of the car??

[richyb66]

They weigh the car to get the actual weights at the IVA test, the 1050Kg is used as a design gross weight which they use as part of the brake calculations. The actual test is pretty involved including brake pedal effort, so far more comprehensive than an MOT.

 

They take all the readings at the test then stick all the figures in a spreadsheet which decides whether it's a pass or a fail.

[Guest mower man]

My s7 comes in at 805 k wet HTH mower man [mick]

[Guest Bluey]

many thanks guys

[Longboarder]

The manufacturer is to assign the Maximum Gross Design Weight (MGrossDW) and the Maximum Design Axle Weights(MDAxleW). These 'should' be marked on the Vin plate. They are not the weight of the car but are safe limits that the structure of the car has been engineered to safely support without failure.

At IVA the car will be weighed with spare wheel, reasonable tools, full tank of fuel and all fluids onboard and then each axle weighed. This gives real figures for total kerb weight, front axle kerb weight and rear axle kerb weight. The vehicle length will be measured, noting also the distances from the front of the car to the front axle, to the base of the seat backrest, to the rear axle and to the centre of the luggage space. Passenger weight is assumed to act at a point 200mm in front of the seat backrest and luggage weight in the centre of the luggage space. Each person is assumed to weigh 68kg and have 7kg. So an extra 2 x (68 + 7) = 150kg in a seven.

Now the calculations.

The first is the sum of the MDAxleWs must be equal to or greater than the MGrossDW. The declared MGrossDW is then split in proportion to the actual position of the axles measured from the front of the car. The MGrossDW is considered to be in the centre of the car. Neither MDAxleW must be exceeded.

In a seven the axle positions tend to give close to a 50/50 split. You have to assume GBS have done their sums and got this right. IMO they should overspecify both MDAxleWs by 100kg so MGrossDW 1050kg, MDAxleWs 625/625 (1250kg).

 

Now 150kg is added to kerb weight and checked to be less than MGDW. Still OK?

IVA has measured each axle weight, and the position of the point 200mm in front of the seat back and the centre of the luggage space. But IVA now needs to know how much of the 150kg to add to each axle. Using moments round the front axle and knowing the distance to that 136kg of people, the rear axle and the 14kg of luggage IVA works out how much extra weight is on the rear axle. Change the fixed point to the rear axle and recalculate to work out the extra on the front axle. (Or just take the first answer from 150. Should be the same)

Now IVA checks these recalculated kerb axle weights do not exceed the MDAxleWs.

 

And you're done. And breathe!

 

Nigel

[Guest MarkB]

They weigh the car to get the actual weights at the IVA test, the 1050Kg is used as a design gross weight which they use as part of the brake calculations. The actual test is pretty involved including brake pedal effort, so far more comprehensive than an MOT.

 

They take all the readings at the test then stick all the figures in a spreadsheet which decides whether it's a pass or a fail.

 

 

Oi! Iva use the same system as an mot station to work out brake effort, the only difference is that we do not weigh the car although many brake rollers have this facility, if the brakes do not lock, efficency against the weight comes into play, if all brakes lock off then weight becomes irrelevant to us... But not to the iva.... Infact.... We do too much for our pittance of a fee

[richyb66]

I don't ever recall seeing on MOT tester measure the pedal effort when he's doing the test and then take measurements at 5 different percentages.

 

That's why I implied theIVA test was more comprehensive.

[Guest Brian T]

Each person is assumed to weigh 68kg and have 7kg. So an extra 2 x (68 + 7) = 150kg in a seven.

 

That's it, the wifes got to lose 15 kgs to make up for my 15 Kg extra

 

The MOT test station I took mine to yesterday had an all singing/dancing brake tester and he did the whole works. He said he didn't have to but did it as a favour as the brakes (car in entirity) is an unknown quantity to me, got it on Tuesday.

[Guest MarkB]

I don't ever recall seeing on MOT tester measure the pedal effort when he's doing the test and then take measurements at 5 different percentages.

 

That's why I implied theIVA test was more comprehensive.

 

Really... Never seen? Then either your tester has used a decelerometer or he ain't tested your brakes, the whole point of a roller brake tester is to measure brake effort, although it can come in handy for bump starting some older cars and the reading column makes a good tea shelf, our second system cost way touch money and you can't even rest your cuppa down, the inconcideret barstewards put the readings screen too high .

 

Anyway back to the point, each rbt consists of 6 brake effort tests (percentages calculated if no lock) 2 balance tests, 2 brake applicat ion tests, again all calculated to percentages,fortunaly the mot computer works it all out for us but there are times when we have to actor the dust off our brains and do a bit of maths.