620 owners

[JNC]

Quick question , a friend of mine has just upgraded to a 620S from a Duratec with RBTB's , Obviously both are 2Ltr Duratec , What mpg are  other 620S drivers getting ?.

[Alan Archer]

Very little from what I have heard!

[JAL]

I've heard the 620S SV will give you 140-150 miles on a tank.... if you drive it carefully.

Doug

[ScottR400D]

Does it really matter? 

I've had my R400 for over 2 years and have no idea what mpg it does.  

[JNC]

Yes it matters !! The car is only a week old and it uses quite a lot moor fuel than the previous car on RBTB's  and he wants to know if it's ok !. And if others are the same  ?.

[DJ.]

50% more power is probably going to require 50% more fuel, all other things being equal. Sounds like the 620 needs a bigger tank!

[JNC]

DJ, 50% more power ?  Old car 220 bhp new car 310 bhp = 90 bhp extra  can't see your maths ?

You may be right about size of tank ! 

[nigelpugh]

I've just had my 620R ( S3 ) fuel gauge recalibrated as it always under read. Since new.

I previously could only get about eighteen litres in when it was showing empty, but it Should be able to take closer to thirty litres from empty to fill it up.

Having said that I managed to get one hundred and twenty miles on one tank, from indicated full to the red quadrant .

Now its been recalibrated I have driven an indicated one hundred and ten miles and it's still showing a quarter left on the tanks so I believe one hundred and forty to one hundred and fifty range should be the normal range.

[Mark w]

On the road  and a light throttle I can drive 150 ( maybe up to 170 ) miles before I need to refill . It's really reasonably economical at circa 30 mpg , my old R400 (k) didn't do much more .

On track it's a different story ..........maybe 10 or 15mpg ? 

The gauges are very pessimistic . Mine was like Nigels , dropped right down to the red but still had half a tank left .

I sorted this by removing the pump and sender unit and bending the float arm to change the reading .

Had to do this a few times before I got it exactly right .

Now the gauge reads full for ages before the needle starts to move but it's much more accurate when you really need it , the last 30 miles before the engine stops ! 

[JNC]

Unfortunately I neglected to say S3 and occasionally a lead foot !

[craigyb]

I have an R400 with RBTBs. On a gentle run I reckon it costs about 20p/mile, so roughly 25mpg. Not that I care...

Also curious about how to fix the fuel gauge, as mine has the exact behaviour described above.

[Jonathan Kay]

Also curious about how to fix the fuel gauge, as mine has the exact behaviour described above.

Several options (including Mark w's above), but I suspect that the most popular would be a black box between the sender and the gauge that you calibrate when you know that the tank is empty and full. They are commercially available. I once tried to find a circuit diagram for those who would like a more Sevenesque solution... 

Jonathan

[JNC]

CraigyB ?? He has px'ed the car with RBTB's and want's to know what others with 620's are getting !! not an R400

[ScottR400D]

Tell you what, why don't you refer your 'friend' back to Caterham if you don't like the responses you're getting here?

 

 

[JNC]

ScottR400D , sorry to offend you I thought you had not understood my question as people are answering for r400 not 620s ! He was expecting an increase but wasn't sure what to expect ? . If you can get a straight answer from CC you are lucky     

[Mark w]

In response to Jonathan's comment re calibration , I looked at getting one of these 

https://www.spiyda.com/magento/index.php/fuel-gauge-wizard-mk3.html

Does anyone know of other options that do a similar thing ? 

[DRH]

Cateham need to come up with a larger car/tank, an extra few inches at the back wont even notice.

Back in the day when 100bhp was the norm the tank size was ok but with the power they are producing today soon you will be having to do a pit stop on  the track .

[Gnockoff]

Cateham need to come up with a larger car/tank, an extra few inches at the back wont even notice.

They have, it's called a SV

[JNC]

Yes that's one of his problems he's gone from a 220 SV to a 620 S3 , 

[kalibre46]

Been through my first tank now in the 620S. Got to midway into the red zone on the gauge before squeezing 22 litres in at a station. So based on my mileage I think I'd only have got 100 miles out of the full tank. Less than expected given I wasn't going above 5k rpm, but it could just be because it is brand new and it needs to settle down.

[Mark w]

But 22 litres is only 66% of the tank capacity .

You have the same issue I did . The gauge is telling you to fill up too early .put a can in the boot and drive until the engine stops , then you will really know how far you can go on a full tank . 

[kalibre46]

Yeah so I knew the gauge was going to be out (it's a Caterham after all), but the slight surprise for me was the range. I did 70 miles on those 22 litres....

[JNC]

Thanks for the serious 620 answers , it's become apparent that the gauge's are really unreliable  !

[Alan Reeves]

70 miles on 22 litres

i do hope that improves or it will be short blats and short in the pockets

[kalibre46]

Me too! I'm hopeful it just needs to settle down into something a little better. I'd be happy with 150 miles from a tank (circa 22mpg) but 100 (15mpg) would be disappointing. Having driven a Tesla for the last two years filling up with petrol was an odd experience yesterday anyway, but it looks like I better get used to it again! lol.