fuel economy 101

[warpc0il]

I seem to recall that Tony used to report mpg figures that we would all like to replicate, even when taking advantage of the sc power, at least as much as you can on the road.

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[PeteH]

New Duke. If an s1 was doing 4500rpm at 70mph in sixth gear, then it would be at 9000rpm at 140mph. That's a long way from correct. In fact, even my 5.1 diff doesn't lower the gearing by that much (I do 3950rpm at 70mph in sixth). The RX-8 reaches its top speed of 146mph in fifth gear, and at very close to peak power (8400rpm). That's exactly what my spreadsheet predicts will happen. I'm pretty confident of my numbers....

But, to prove it, if someone would like to use a gps to drive their s1 at exactly 70mph, then get a snap shot of their obd11 while it is displaying the revs, I'd be surprised if it was very far away from 3400rpm.

Chris. The science would tell us that the supercharger has marginally reduced the efficiency of your engine. The supercharger consumes a small amount of additional petrol in order to do its thing. If, however, this means you can use a higher gear in the same situation, and if that means the reduced engine losses are greater than the increased supercharger losses, then you could, in theory be more economical. But generally, if a supercharger isn't clutched then it will consume some fuel. It's why turbo charging won the boost war for OE fitment.

(Dave. Tony had 372bhp, if I recall.... #JustSaying)

[goodeggbob]

Chris,have you found a new fuel? that may explain the carrier bag and spade on the beach in Aber.

[ChrisHolmes]

Ermmm..... Was the guy who owned it the same as the one who used to drive it by any chance?

For the popular MGB 3.5 v8 (sd1) engine conversion you had to disable overdrive on 3rd as well otherwise the torque would destroy it!

Just to get closure on this thread detour, the Rapier was owned by a work colleague, who lost his license for a year, so I got to "borrow" his car, as long as he wanted to go somewhere

That same car re-appeared many years later, now owned by a mutual friend, only fitted with an RX7 engine

Getting back, nearly on topic, I have no idea what transmission it was running but it took off like a scalded cat and was hard against the rev limiter at 110mph in top, on the original wheels, until he fitted rear tyres from a Transit van to increase the gearing. He then took it to Santa Pod for a RWYB meet and it came home on a flatbed...

[ChrisHolmes]

Real world mpg driving from Cumbernauld to Cheltenham, 3 stops on the route 70-80mph mostly, tyres are 245/35 x 18 so speedo reads a bit fast and also will of course record more miles so the MPG number will be a bit lower, but still a good result.

search.php?st=0&sk=t&sd=d&sr=posts&keyw ... 1&start=25

Miles Covered 350
Fuel to fill 56.89ltrs (12.51gals)
MPG 27.98

[Dentist]

since this topic is off by gear ratio.

the gearbox graph should match engine out put.
ray diagram
https://qph.fs.quoracdn.net/main-qimg-b ... 53e5d.webp

[ChrisHolmes]

since this topic is off by gear ratio.

the gearbox graph should match engine out put.
ray diagram
https://qph.fs.quoracdn.net/main-qimg-b ... 53e5d.webp

Please expand and post a link that works.

[Dentist]

since this topic is off by gear ratio.

the gearbox graph should match engine out put.
ray diagram
https://qph.fs.quoracdn.net/main-qimg-b ... 53e5d.webp

Please expand and post a link that works.

I think it is better idea to make other topic for gear ratios

[PeteH]

the gearbox graph should match engine out put.

You show a plot that shows the relationship between driveshaft torque and driveshaft speed. I guess you plan to explain something based on this data? If it's not about fuel economy then I'm sure a Mod will be happy to move your posts into another thread, where you can explain what you want to in depth.

[Dentist]

the gearbox graph should match engine out put.

You show a plot that shows the relationship between driveshaft torque and driveshaft speed. I guess you plan to explain something based on this data? If it's not about fuel economy then I'm sure a Mod will be happy to move your posts into another thread, where you can explain what you want to in depth.

crack it ! I'll write when I'll be in mood

[johnbb99]

Well, that finished that, then!

[GreySilver Beast]

God I miss Dentist... His Facebook ramblings aren't half as entertaining as when he has an alias to hide behind...

[ChrisHolmes]

He would say he isn’t hiding because everyone on forums knows who Dentist is. Would you rather have him work on your car or on your teeth?

[johnbb99]

Everyone except yours truly, it would seem.

[qwakers]

Dentist was a insulting, nasty, ill informed and libelous ‘troll’ (still not sure if he was trolling or believed he was right) who in short order managed to insult every industry respected expert on the forum and called everyone who challenged him a idiot

That about covers it, i think

[Dr. FrankenRex]

Yeah, but would you rather discuss coils with Dentist or RobinPZ?

[bigpete8]

Are we sure they weren't the same person