Vmax - Brunters 7/7/7

[LuckyP]

You can probably guess by the fact that I haven't been on earlier, that I didn't get anywhere close to 200mph. Bu66er.

Still waiting confirmation from the timing guys who hopefully will be posting the official times, but the fastest I could see on the timing display (located painfully close to the timing beacons at the start of the braking area, where you have one or two other things to think about!) was....176mph. Pi55 poor!! That is only 5mph faster than Honington with the old ratios. That time the car ran outta revs. This time I got to 176 at around 6,000 RPM. But after the shift from 7,000 in 4th to 5,000 in 5th, the speedo and rev counter just took an age to slowly climb up to 176.

I'll post the vid at some stage. But I now seriously doubt that I have enough power to go any faster.

The surface at Brunters is terrible, a stone chip nightmare.

Had a good run with Leon (207mph) off the line (he kindly gave me a second chance after I fluffed all three changes!!), beat him off the line but his 720 real bhp and slippery shape soon reeled me in at about 120mph, and obliterated me on the straight!!

I had the upper wing removed, tyres at 23/27 and springs at 20/35 (still way too hard)

So bitter sweet really. But a good laugh and a engine was 100% OK.

Porshes, especially RUF ones, are where it's at!! Watch this space!

Lucky, out.

[SimonMaidenhead]

No problems with noise levels then?

[bluesatin]

I think that your top gear is way to tall. I did 175 in the one run i did with my new gearbox last year so should be good for 185 - 190.

I agree about the Porkers. I did 187- the fastest my porker has been at Brunters with a slight tail wind

[LuckyP]

SimonMaidenhead said:

No problems with noise levels then?

Nope - not a noise test in sight!

[LuckyP]

bluesatin said:

I think that your top gear is way to tall.

Explanation please....

[dilley]

I wish I had gone now, I know I can hit 186 on gps but she is really screaming!! I'll go to the next one!! bring on the supercharger, An Ultima has to win.....

[bluesatin]

As you mentioned yesterday when you changed to top the engine drops 2,000 rpm and finds it hard to pick up. Great to have gearing for 212 top speed but as was demonstrated by the RUF to get that type of speed you need 700+ bhp. Two options- more power or slightly better gearing and accept 190 as the top you can get. I would go for option 1!

[LuckyP]

bluesatin said:

As you mentioned yesterday when you changed to top the engine drops 2,000 rpm and finds it hard to pick up. Great to have gearing for 212 top speed but as was demonstrated by the RUF to get that type of speed you need 700+ bhp. Two options- more power or slightly better gearing and accept 190 as the top you can get. I would go for option 1!

Can I open this to the floor? At 140mph given a peak torque of 517 ftlbs @ 4300 and a max CHP of 557@ 6400 what rev would you want to be in?

It took me over half of the available runway to go from 5,000 to 6,000 in 5th.

Dilley, what power are you running? I would say that cars with (AS) HP less that 640 don't stand a chance of 200, regardless of gearing IMHO

Guy,

I hear ya loud and clear, but I reckon the box is good for the 200 quest, just the flippin engine ain't gonna get me there.

[bluesatin]

Nos!

could make all the difference and won't cost a fortune

[Steve_D]

bluesatin said:

Nos!

could make all the difference and won't cost a fortune

Exactly the right time and place to use it.
Can't see it has much use on the road but will make all the difference at that top end challenge.

Looking again at your gear calcs.
By the power of multiplication you have 3643lbf/ft of torque at the wheels when you change into second. 2545 to third. 1749 to fourth. and finally only 1250lbf/ft going into fifth.
Your 176mph was 1171lbf/ft and 200 would have been 987lbf/ft.

More power required my boy.

Steve

[d3vine]

Is Leon's Ruf quicker than Gman's GTR?

[GTRCLIVE]

Where's Jeff when you need him ??? Ooops wrong continent....

More Power then old boy.... how about a 100 shot of Nos ???

[dfpat10]

Lucky,

I’ve been looking closely at 200 MPH or Mach 0.2 as a speed goal myself.

My gear selection is
Rear End Ratio: 3.333
5th Gear Ratio: 0.781
Tire Diameter: 25.913 inches
Vehicle Speed: 200 mph

My calculation for Engine RPM at 200 MPH is 6751RPM

http://www.slowgt.com/Calc1.htm#RPMInGear

And since an LS7 engine redlines at 7000 RPM I therefore should reach 207.3 MPH top speed. So my math is promising, but the only person I’ve seen reach 204 MPH in a street car had engine power of 611 BHP at 6000 RPM with torque of 595 lbs-ft at 4000 RPM. And I see that I noted 67dBA at idle and 85 dBA at full throttle for the Chevy through a Flowmaster exhaust with a turbo. But I need a few tidbits of information like drag coefficient, frontal area, weight (2300lbs?) and mechanical loss through the driveline (15% loss?) so I may calculate the numbers with some accuracy for an Ultima. Looking back at my notes it’s interesting that the Vintage Racers (Ferrari Boxer and Daytona, Lamborghini Countach, Porsche 930 Turbo, DP 935 and BMW M1) all to top out between 160 and 164 mph around the same oval. Just an FYI that I wouldn’t know if it didn’t take two motors and six attempts to reach 204 MPH.

But if an Ultima owner would share a dyno sheet with some accurate run information I'm sure we would be able to have a much higher confidence of reaching 200 MPH or calculating what it would take.

David

Edited by dfpat10 on Monday 9th July 06:07

[bluesatin]

Yes the Ruf is quicker than Gman's ultima. Last time Gman went we was doing in the 190's. We had a slight tail wind and the timing further down the runway than normal so in my case it was good for another 3-4mph.

[LuckyP]

d3vine said:

Is Leon's Ruf quicker than Gman's GTR?

Quicker, no. Faster, at 207 to the Factory's 204 run, yes. IIRC.

Gman's car would have been around the botton bend and away before the slippery shape of Leon's car came into effect. Would have probably been through the timing beacons first to, but not at 207.

[dilley]

Hi Lucky, I am running a As 383ci 535bhp(), I believe this is the same as you??? only difference is I am using the getrag 6 speed.

[deadscoob]

I guess you need a real 600hp to get close to 200mph, slippery shape helps which the Ultima isn't.

RT12s are seriously impressive pieces of kit aren't they. That sort of performance and probably bomb proof too.

[LuckyP]

dilley said:

Hi Lucky, I am running a As 383ci 535bhp(), I believe this is the same as you??? only difference is I am using the getrag 6 speed.

I have the 550 383ci (557hp and 517ftlbs)

Are you wanting to get to 200? I normally wince when peeps say these sort of things, but I say this from a little bit of experience - you'll need more power(if your 535 is AS)!! IMHO!

What to do?

[jeremyc]

LuckyP said:

What to do?

Hello P - nice to meet you at VMax.

How about taking the car to a rolling road to get a benchmark of power at the rear wheels? This will tell you the ultimate limit of the speed you can achieve regardless of the issue of gear ratios.

[LuckyP]

jeremyc said:

LuckyP said:

What to do?

Hello P - nice to meet you at VMax.

How about taking the car to a rolling road to get a benchmark of power at the rear wheels? This will tell you the ultimate limit of the speed you can achieve regardless of the issue of gear ratios.

Hi Jeremy,

Good to meet you too. Thanks for yuo advise on the day. You early shift idea had me thinking all the way home and took my mind off that awfull M25/M1 traffic!

I think that is what I will do. We've been talking here about getting the AS engines dyno'd and I think this might be just the excuse to get me to do it.

Right - question. who is the most respected rolling road operator in the South to conduct this power test?

Pete