Standing mile estimation

Standing mile estimation

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Discussion

ChilliWhizz

11,990 posts

160 months

Tuesday 2nd September 2014
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Back to the gearing, I've always understood that my standard diff (dunno what ratio it is) gives as near as dammit 27mph per 1k rpm in fifth, which is pretty much spot on to QBee's numbers... So at 6k rpm we should be pulling 162mph... beastie has a soft red line at 6.5k rpm, which is 175mph... and she has a hard line at 6.7k rpm, which is 180mph.. I'd doubt we'd see any increase in speed after the soft limiter at 6.5k rpm, so, assuming the 360bhp was sufficient, we have a theoretical top speed of 175mph...

That said, peak power is produced at 6.1k rpm, so that's 165mph... but it's not unreasonable to assume that given the right conditions (not into a headwind, not uphill etc) that the soft limiter max of 175mph is achievable...

The limiters are set in the MS2, so easily changed.... but they protect the engine in the lower gears, when hitting 60mph could be achieved in as little as 3.8 seconds, and over revving is an obvious risk in lower gears where everything is happening very quickly....

Looking forward to how it goes Derek, and would very much like to know (if possible) how much bhp you use to break the 180mph barrier...

Good luck with it mate wink

Alexdaredevils

5,697 posts

178 months

Tuesday 2nd September 2014
quotequote all
I was at 6600rpms at 174mph Chilli

ChilliWhizz

11,990 posts

160 months

Tuesday 2nd September 2014
quotequote all
Alexdaredevils said:
I was at 6600rpms at 174mph Chilli
Was that an indicated on the speedo Alex? The 27mph thingy suggests you should have been doing 178mph... which actually is only 4mph out... so it kinda stacks up... smile Take it that was on a track somewhere? whistle

Alexdaredevils

5,697 posts

178 months

Tuesday 2nd September 2014
quotequote all
Garmin sat nav, wheel/tyre size would make a small difference, then again I had no proof on how accurate the rev counter was

Yes definitely a track, definitely not the A1 on that downhill section that opens up to 4 lanes

Edited by Alexdaredevils on Tuesday 2nd September 20:36

Hoofa

3,151 posts

207 months

Tuesday 2nd September 2014
quotequote all
Alexdaredevils said:
Garmin sat nav, wheel/tyre size would make a small difference, then again I had no proof on how accurate the rev counter was

Yes definitely a track, definitely not the A1 on that downhill section that opens up to 4 lanes

Edited by Alexdaredevils on Tuesday 2nd September 20:36
Yeah that's the bit chillis carpet get stuck under the loud pedal smile ..... Sorry could resist

SILICONEKID345HP

14,997 posts

230 months

Tuesday 2nd September 2014
quotequote all
I don`t understand why my car would not go any faster than much lower powered Chimaeras at Bruntingthorpe ,I only achieved 130mph ,same as a standard 4l .. I wonder why .

The only difference is i get to that speed much quicker .

Alexdaredevils

5,697 posts

178 months

Tuesday 2nd September 2014
quotequote all
Daz don't forget I had a 5 mile run up and a 5 mile braking zone if I wanted





On this north Russian test track

SILICONEKID345HP

14,997 posts

230 months

Tuesday 2nd September 2014
quotequote all
Alexdaredevils said:
Daz don't forget I had a 5 mile run up and a 5 mile braking zone if I wanted





On this north Russian test track
sounds bloody scary .i hated going 130mph .It felt ok but i did not like it .

QBee

20,905 posts

143 months

Tuesday 2nd September 2014
quotequote all
SILICONEKID345HP said:
I don`t understand why my car would not go any faster than much lower powered Chimaeras at Bruntingthorpe ,I only achieved 130mph ,same as a standard 4l .. I wonder why .

The only difference is i get to that speed much quicker .
Take the handbrake off next time?

Sardonicus

18,928 posts

220 months

Tuesday 2nd September 2014
quotequote all
SILICONEKID345HP said:
I don`t understand why my car would not go any faster than much lower powered Chimaeras at Bruntingthorpe ,I only achieved 130mph ,same as a standard 4l .. I wonder why .

The only difference is i get to that speed much quicker .
WTF Daz no wonder your always on about final drives & gearing eek are you sure your speedo is working properly confused

SILICONEKID345HP

14,997 posts

230 months

Tuesday 2nd September 2014
quotequote all
QBee said:
Take the handbrake off next time?
I easily and quickly got to 130mph in the MGRV8 and it felt solid as a rock ,that was only a 190 hp Rover v8 . I`m wondering why the v8 seems to run out of steam after 130mph but the speed six just keeps going .





Alexdaredevils

5,697 posts

178 months

Tuesday 2nd September 2014
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Even my diesel Volvo managed 143mph gps confirmed

Come on Daz keep up

SILICONEKID345HP

14,997 posts

230 months

Tuesday 2nd September 2014
quotequote all
Alexdaredevils said:
Even my diesel Volvo managed 143mph gps confirmed

Come on Daz keep up
I just feel my car would be suited better with the 3.08 ratio ,after having the GKN 3.31 i just hate the 3.45 ratio ,ok it picks up better at the beginning but you loose out later on . 2700rpm at 70mph just seems wrong .

I want lower rpm cruising ,I believe what Derek said regarding a 3.08 is suited for engines above 300hp.




QBee

20,905 posts

143 months

Wednesday 3rd September 2014
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Not changing mine!
It comes down to how and where you use the car.
On the pubic road I tend to drive between 0 and 70 mph, using the torque and power to accelerate quickly and nip past stuff. On the motorway I cruise around 70 mph.
On the track, even with fairly long straights, I don't see more than 125 mph and quite frankly I would give the car a breather at places like Silverstone and Thruxton.
At the Pod ........ Well, I don't do podding.

At Cadwell Park on Monday I enjoyed the first time ever that Graham n's Cerbera 4.5 hadn't overtaken me. I had grown a pair and was taking the corners as fast as him, and the straights are short. And Mat, in his 210 bhp 4 litre, kept up too.

To answer your question, Daz, our power band and gearing is set to give us lots of grunt at every day speeds, between 2000 and 5000 rpm, with peak torque around 4000. The AJP8 has its power higher up - chatting to Graham, with a rev limit over 7000, he can pull 90mph in second gear. The Speed Six has its peak power above 6000 rpm, so needs to be revved to get the best out of it. On a cross country run, a 4 litre RV8 will quite possibly be quicker than a 3.6 Speed Six (mine was) because the Speed Six driver struggles to access he extra 140 horses under those conditions. But a Speed Six will still be pulling hard at runway speeds, when you and I have gone past out peak torque quite a while back.

db484bhpv8

Original Poster:

8,655 posts

219 months

Wednesday 3rd September 2014
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Hey Richard, whats your guesstimation for my speed at the mile NA, 275 @ wheels?

RichardD

3,560 posts

244 months

Wednesday 3rd September 2014
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db484bhpv8 said:
Hey Richard, whats your guesstimation for my speed at the mile NA, 275 @ wheels?
Can we work on fly numbers plz, it saves me editing all the individual bhp/rpm entries as I don't have a NA model for your car (thought I did, must have done some tidying up!)

315bhp @ 5500rpm and 340lb/ft at 4500 ? That would be close to 145mph at the mile smile.

db484bhpv8

Original Poster:

8,655 posts

219 months

Wednesday 3rd September 2014
quotequote all
RichardD said:
Can we work on fly numbers plz, it saves me editing all the individual bhp/rpm entries as I don't have a NA model for your car (thought I did, must have done some tidying up!)

315bhp @ 5500rpm and 340lb/ft at 4500 ? That would be close to 145mph at the mile smile.
I had 328 at the fly according to Surrey rolling road.
Also saw 152 on the TomTom without gas (i think) at the BNG which i estimated was 0.8 mile
I saw 158 later in the day with a 70 shot

RichardD

3,560 posts

244 months

Wednesday 3rd September 2014
quotequote all
db484bhpv8 said:
I had 328 at the fly according to Surrey rolling road.
Also saw 152 on the TomTom without gas (i think) at the BNG which i estimated was 0.8 mile
I saw 158 later in the day with a 70 shot
148mph with the 328bhp, but then realised that it was 0.37 drag coeff, so reducing that to 0.35 changed the speed to 150mph.

db484bhpv8

Original Poster:

8,655 posts

219 months

Wednesday 3rd September 2014
quotequote all
I wonder how much the drag is reduced when lowering the car. Maybe tape the shuts (only joking).
I think my blended Lupo's will give my another mph at the top end too smile

Alexdaredevils

5,697 posts

178 months

Wednesday 3rd September 2014
quotequote all
How much bhp is needed for 200 210 and 220 mph, not standing mile unlimited