Could a 951 reach 200+ mph?
....
08-04-2006, 04:35 AM
#33
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Originally Posted by HIGHBOOST
I just love clicking on threads that I'm excited to read/learn. And they turn out like this
Wish I had the answer...
Modded to all living hell, a 951 w/STOCK gearing will ONLY hit 167mph at 6400rpm redline... I do not care if it has 2000RWHP, it can ONLY go so fast at given gearing
It sounds like the Ocean Blue 951 w/340rwhp is AWESOME! I LOVE these cars in blue, but, to hit 200mph- think about it- a 993TTS & 996TT will both barely break 190mph w/>400HP/TQ & 6-sp close ratio gearing, spaced to allow max top speed, etc- they ALSO have lower Cx AND Frontal Area... A 951 is .33 & 20.4 sq/ft. The 993/996 is .30 to .31 & ~19.5 sq/ft. This would allow the 993/996 to hit 200 w/~40RWHP LESS than a 951 & they STILL can't break ~192 or so w/out a hurricane behind them & mods galore. A 951 would definately need more than 400rwhp. Now, that doesn't mean the Ocean Blue 951 didn't do it, but maybe the 340rwhp claim is a bit conservative- by ~75HP...? Either way, he'd need dif gearing &/or higher revs....
SCOTT GOMES, one of the highest-HP 951/968 engine builders in the world, claims ~208mph in his personal car- he had >600HP & almost 8000rpms!!! By my calculations, it would be 7969rpms.
A 951 w/stock FD (3.38) & 944 NA 5th gear (.72) would redline at ~193mph.
To get 194mph from stock gearing (3.38 X .83) would take >7400rpms.
Even w/HUGE 285/35/18 tires- this is a bigger RD (25.85") than anything I've ever heard of for one of these cars & IF you COULD squeeze one in (I don't see how but would love to know), you'd STILL only hit 174 @ redline- OR, would need >7100rpm to hit 194 OR >7300 to hit 200mph.
A 285/35/18 w/3.38FD & .72 5th would hit 201mph @ 6400rpms- again, that's too big of a wheel & you'd STILL need TONS of HP to overcome the huge hole b/t 4th & 5th...
Even a slightly large, but still common 265/35/18 (25.30") would only give 171mph @ 6400 & 200mph @ almost 7500...
Konstantin's video is very impressive- see how fast he rolls through 120 - 160 or so- it compares about evenly w/a 951S running through 3rd!!! That's amazing & he STILL slows down way fast up top.
I was in a VR6 Jetta YEARS ago- this one was BADASS- it would beat any VR6 Corrado I've ever been in & I've been in a few- we had it up to 130 or so EASILY & at 130+ I swore up & down it would break 150 EASILY- the question to me was whether or not it would break 160, assuming it wouldn't redline way too early- turns out, redline was ~156, but... We got a chance one night- it felt like it hit a wall ~140 & we BARELY hit 148 or 149... ANYONE who EVER rode in that car w/me SWORE to God above that it would break 150- most thought 170-180 would have been possible. B/c at 120 or so, it REALLY felt like it had 40mph or more left- it was pulling HARD & felt as if no end were in sight... just goes to show...
It takes more than double the HP to hit 200 as it does 150. Air resistance is an exponential force. Think of how many cars w/barely 100HP can hit 100mph- hell, my 118HP Integra would hit ~123 (131 on BIG hills). A 951 has similar frontal area, less Cx, & more than TWICE the HP at just the right point in the gearing to max out it's top speed & it barely clears 160mph. The gearing is maxed out for top speed- That's why these cars can hit 162mph- no magic- A Turbo S hits max HP @ 6000rpm & that's ~157mph.
In the late '80's, VERY FEW cars could even hit 150 & the Turbo S would hit 162- think about it... Hitting 200mph is an entirely different world- Especially since 8yrs later, a $150K 993TTS was barely >190mph... The 996TT never seemed to be any faster & is several years further ahead in technology- What will the 997TT do- Anyone? Bet it still wont hit 200...? Why would anyone think making a 20yr old Porsche break that wall would be easy? These cars were never geared for that & just b/c one has the HP doesn't mean they can hit a higher top speed- increasing HP does not change the amount of times a wheel must turn per given amount of time to make a car travel a certain speed- gearing & HP are two totally dif things... You have to have the HP, that's a given. But, you ALSO have to have either the gearing, the revs, or BOTH!
08-04-2006, 04:48 AM
#34
Nordschleife Master
That's true Robby, but if you have a 200+mph 5th gear, you will need HP to pull the car thru that longer gear.
My car is bone stock except for 15psi guru chips and 17" Cups. I think the rev limiter is at 6800rpm, irrc. I was able to pin the needle at 175mph indicated. (just over 167mph on the GPS) The car ran out of RPM's.. not power. That said, if we increased the 5th gear to reach 200mph at 7000rpm, my car might not have enough power to quickly pull that gear up to 175mph, let alone 200mph... hence the problem.
I'm not sure that I agree with Waterguy that you'd need 450+hp to reach 200mph. I think it can be done with less power and better gearing. (Sorry Don, we can argue about this on Saturday morning...
)
My car is bone stock except for 15psi guru chips and 17" Cups. I think the rev limiter is at 6800rpm, irrc. I was able to pin the needle at 175mph indicated. (just over 167mph on the GPS) The car ran out of RPM's.. not power. That said, if we increased the 5th gear to reach 200mph at 7000rpm, my car might not have enough power to quickly pull that gear up to 175mph, let alone 200mph... hence the problem.
I'm not sure that I agree with Waterguy that you'd need 450+hp to reach 200mph. I think it can be done with less power and better gearing. (Sorry Don, we can argue about this on Saturday morning...
)
08-04-2006, 05:46 AM
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Rich- you're absolutely right- I thought I had alluded to this somewhere in my above novel, but may not have. This is definately the prob w/doing the .72 5th w/normal 3.38FD- you'd have a HUGE hole b/t 4th & 5th. Most would say that if you have HP capable of hitting 200 in the first place, then you'd have the power to get through the gear, but this is not true- you have to have the HP & TQ in the right places- a nice linear spread- area under the curve as opposed to peaky Honda-like power curves.
Tall gears allow the top speed w/out over-revving, BUT, they also hamper acceleration- gearing is simply a multiplier. The best way to do it is to have more gears that are spaced evenly. A 968 would not do well b/c it's 6th is shorter than 951's 5th. BUT, a 968 w/custom gears 2-6...? I'm sure there are cheaper ways... There's a group of guys trying to get a run of tall 968 FD's made through PHII- I think it's a 3.22 they're going for- gives ~189 in 6th- the 968's top 3 are so close together, but they do allow better acceleration. It's really all a question of hitting the #'s right to make the gears effective for top speed.
Tall gears allow the top speed w/out over-revving, BUT, they also hamper acceleration- gearing is simply a multiplier. The best way to do it is to have more gears that are spaced evenly. A 968 would not do well b/c it's 6th is shorter than 951's 5th. BUT, a 968 w/custom gears 2-6...? I'm sure there are cheaper ways... There's a group of guys trying to get a run of tall 968 FD's made through PHII- I think it's a 3.22 they're going for- gives ~189 in 6th- the 968's top 3 are so close together, but they do allow better acceleration. It's really all a question of hitting the #'s right to make the gears effective for top speed.
08-04-2006, 10:42 AM
#36
Originally Posted by Robby
Even w/HUGE 285/35/18 tires- this is a bigger RD (25.85") than anything I've ever heard of for one of these cars & IF you COULD squeeze one in (I don't see how but would love to know), you'd STILL only hit 174 @ redline- OR, would need >7100rpm to hit 194 OR >7300 to hit 200mph.
08-04-2006, 10:59 AM
#37
Captain Obvious
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Originally Posted by hally
Speaking of the salt flats, anyone seen the NZ movie, 'Worlds Fastest Indian' i thought it was great, Anthony Hopkins, true story.
http://www.worldsfastestindian.com.a...er/medium.html
http://www.worldsfastestindian.com.a...er/medium.html
I saw it too a few months ago. Perfectly captures the spirit of a DIY gear head!
Anyone can buy performance parts from a catalogue and bolt it on their vehicle, but it takes talent to make it yourself.
08-04-2006, 12:52 PM
#38
Three Wheelin'
Originally Posted by Rich Sandor
My car is bone stock except for 15psi guru chips and 17" Cups. I think the rev limiter is at 6800rpm, irrc. I was able to pin the needle at 175mph indicated. (just over 167mph on the GPS) The car ran out of RPM's.. not power. That said, if we increased the 5th gear to reach 200mph at 7000rpm, my car might not have enough power to quickly pull that gear up to 175mph, let alone 200mph... hence the problem.
I'm not sure that I agree with Waterguy that you'd need 450+hp to reach 200mph. I think it can be done with less power and better gearing.
I'm not sure that I agree with Waterguy that you'd need 450+hp to reach 200mph. I think it can be done with less power and better gearing.
Aerodynamic drag increases as the square of velocity (not exponentially as someone said), and so the HP requirements increase as the cube of velocity. I actually said that you need 400+ rwhp to reach 200 mph (not 450.) In theory, you could do it with as little as 380 rwhp, but it would take you an looooong time to get there.
Sorry, I won't be out for tomorrow's drive.
08-04-2006, 01:26 PM
#39
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I have been on the tire/wheel sites and entered different tire and wheel sizes into their calculators and I think with 18" wheels it added about 12-14% to the final drive ratio.
08-04-2006, 01:27 PM
#40
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Also, in regards to "rev limiter", and I am not suggesting this but, I have heard in here plenty of times on the road and track, people running up to 7K rpms and more and being ok.
but, I have heard in here plenty of times on the road and track, people running up to 7K rpms and more and being ok.
08-04-2006, 05:45 PM
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While I'm not showing this off to be PROOF, it adds some TRUTH to the story...
This is the exact same sticker that resides in the driver side rear window of Scotts Car...
https://www.nostalgicracingdecals.co...CLUB%20640.gif
This is the exact same sticker that resides in the driver side rear window of Scotts Car...
https://www.nostalgicracingdecals.co...CLUB%20640.gif
08-04-2006, 05:53 PM
#42
Originally Posted by BigNNasty
While I'm not showing this off to be PROOF, it adds some TRUTH to the story...
This is the exact same sticker that resides in the driver side rear window of Scotts Car...
https://www.nostalgicracingdecals.co...CLUB%20640.gif
This is the exact same sticker that resides in the driver side rear window of Scotts Car...
https://www.nostalgicracingdecals.co...CLUB%20640.gif
08-04-2006, 08:02 PM
#44
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Waterguy- I mis-spoke on the "exponential" thing- really couldn't think of the way to phrase that. But, the stock redline's 6400- not 6480. Of course, the rev limiter cuts in at 6500, unless defeated. And, yes, Rich's #'s are very close by my calculations too- I'd have no trouble believing that...
As far as taking a long time to get to 200mph, etc, it really just depends- All cars take a long-*** time to get to their drag limited top speed- Rev limited is a dif story. That 260mph Bugatti doesn't take much time to hit 200, but I'll bet b/t ~230 & ~260 or so, it takes seemingly forever. Again, rev-limited is different, like VR6 Corrados, e36 M3s, & even 951S w/3.89FD's. So, keeping that in mind- take a 951 w/7K rpm redline, taller RD rear tires & .72 5th gear, & give it 1000HP like Bob Norwood's Doom II, or one of Scott Gome's bad-*** HP engines & you'd have 200mph in no time. Of course, gear it correctly, & it would probably be capable of hitting 250mph. Certainly those last 25mph or so would take awhile though- get close to the drag limit & it always takes some time.
Todd- the percentage dif depends on tire size- rolling diamter. A stock Turbo has a 24.86" RD. Turbo S - 24.68" RD, & 968 M030 - 25.03" RD. Using the 24.86, a standard 18" upgrade of 265/35/18 (25.30) is only 1.77% dif. The redline would go from ~167 to ~171, or ~2.4% dif. Go to a 285/35/18 & you'll have a RD dif of ~4% & a redline speed dif of 7.5 or 4.5%. Not sure about the final drive dif, but in the end, at the redline speed, it's not as much as people think. Even w/those 285/35/18's AND a .72 5th, you'll BARELY scrape 200mph at 6400rpms.
MPD47- wait a sec- I'm not trying to contradict you, but I've never seen anyone w/a 285/35/18 OR 295/35/18- I've asked about this TONS of times as I'm dying to run a 285/35/18 w/a 245/40/18 up front, but keep getting that a 275/35/18 is the biggest I could go (OR a 275/40/17, but that's 17" rim) w/out rubbing. My question to you is- are you 100% SURE that you don't mean a 285/30 OR a 295/30/18? Even a 295/30/18 is smaller than a 255/35/18.
295/30/18 = 24.97
285/30/18 = 24.73
then,
295/35/18 = 26.13
285/35/18 = 25.85
275/35/18 = 25.58
275/40/17 = 25.66 - this is the largest I've seen, but I'd LOVE to know if larger is possible- if the 285/35/18 WILL go, do you have any idea what type of offset I'd need?
thanks
As far as taking a long time to get to 200mph, etc, it really just depends- All cars take a long-*** time to get to their drag limited top speed- Rev limited is a dif story. That 260mph Bugatti doesn't take much time to hit 200, but I'll bet b/t ~230 & ~260 or so, it takes seemingly forever. Again, rev-limited is different, like VR6 Corrados, e36 M3s, & even 951S w/3.89FD's. So, keeping that in mind- take a 951 w/7K rpm redline, taller RD rear tires & .72 5th gear, & give it 1000HP like Bob Norwood's Doom II, or one of Scott Gome's bad-*** HP engines & you'd have 200mph in no time. Of course, gear it correctly, & it would probably be capable of hitting 250mph. Certainly those last 25mph or so would take awhile though- get close to the drag limit & it always takes some time.
Todd- the percentage dif depends on tire size- rolling diamter. A stock Turbo has a 24.86" RD. Turbo S - 24.68" RD, & 968 M030 - 25.03" RD. Using the 24.86, a standard 18" upgrade of 265/35/18 (25.30) is only 1.77% dif. The redline would go from ~167 to ~171, or ~2.4% dif. Go to a 285/35/18 & you'll have a RD dif of ~4% & a redline speed dif of 7.5 or 4.5%. Not sure about the final drive dif, but in the end, at the redline speed, it's not as much as people think. Even w/those 285/35/18's AND a .72 5th, you'll BARELY scrape 200mph at 6400rpms.
MPD47- wait a sec- I'm not trying to contradict you, but I've never seen anyone w/a 285/35/18 OR 295/35/18- I've asked about this TONS of times as I'm dying to run a 285/35/18 w/a 245/40/18 up front, but keep getting that a 275/35/18 is the biggest I could go (OR a 275/40/17, but that's 17" rim) w/out rubbing. My question to you is- are you 100% SURE that you don't mean a 285/30 OR a 295/30/18? Even a 295/30/18 is smaller than a 255/35/18.
295/30/18 = 24.97
285/30/18 = 24.73
then,
295/35/18 = 26.13
285/35/18 = 25.85
275/35/18 = 25.58
275/40/17 = 25.66 - this is the largest I've seen, but I'd LOVE to know if larger is possible- if the 285/35/18 WILL go, do you have any idea what type of offset I'd need?
thanks