Powerhaus 200mph
09-12-2003 | 02:32 PM
#46
Addict
Rennlist Member
Rennlist Member
Joined: May 2001
Posts: 2,099
Likes: 7
From: A suburb of Silicon Valley, CA
In 1980 Porsche, in an attempt to give the water cooled 4 cylinder series cars an image boost, came out with the 924 Carrera GT and took it to Le Mans. The main thrust was to pit the 924 Carrera GT against the 911 (or more accurately the 935). With 320 bhp @ 6500 rpm, weighing 945 Kg, the CGT LM could only muster 175 mph on the Mulsanne straight. This was a sobering 50 mph slower than the 935.
Even with the top speed disadvantage, the CGT LM finished a notable 6th. That against even the prototypes. The little car that could, achieved this great feat with great fuel mileage and reliability, both items keeping the car on the track and not in the pits.
How does this relate to this topic? make your own conclusions. I do know that 200 mph in a daily driven (the key being drivable daily) street car, has long been a holy grail for the likes of Porsche, Ferrari, Lamborgini, Aston Marton, etc. Sort of like breaking the sound barrier was for the aeronautical folks.
Even with the top speed disadvantage, the CGT LM finished a notable 6th. That against even the prototypes. The little car that could, achieved this great feat with great fuel mileage and reliability, both items keeping the car on the track and not in the pits.
How does this relate to this topic? make your own conclusions. I do know that 200 mph in a daily driven (the key being drivable daily) street car, has long been a holy grail for the likes of Porsche, Ferrari, Lamborgini, Aston Marton, etc. Sort of like breaking the sound barrier was for the aeronautical folks.
09-12-2003 | 02:57 PM
#47
Instructor
Joined: Mar 2003
Posts: 202
Likes: 0
From: vancouver, canada
Correct me if I'm wrong but Porsche, Ferrari and Aston Martin have never built 200mph street cars. Ferrari's F40, F50 and Enzo are 200+ but they are rare limited editions. The only Porsches over 200 are race cars or RUF modified. The only factory production cars over 200 (and just barely) are the Lamborghini Diablo and Murcielago.
09-12-2003 | 03:15 PM
#48
Three Wheelin'
Joined: Aug 2002
Posts: 1,388
Likes: 3
From: Vancouver, BC
According to my calculations, and assuming stock 951 aerodynamics (Cd = 0.33, frontal area = 20.4 square feet), you would need 380 rwhp and matching appropriate gearing to hit 200 mph at the horsepower peak.
The gearing could be achieved at a reasonable rpm by using a combination of tall rear tires (eg 245/45-18, 26.7" diameter) and the tall 5th gear set from a 1983-1987 US model 944 (0.73:1), which is a direct bolt-in to a 951 tranny. This particular combination would hit 200 mph at 6,400 rpm, which would be a reasonable HP peak for a 951 with improved breathing (big turbo, exhaust, intake/head polishing, etc.)
Building a 951 engine to 380 rwhp@6,400 rpm should be doable, and probably has been done by several tuners. You then need a custom-calibrated speedo a la Dfastest, or a GPS datalogger, since you may not be watching the speedo anyway. Oh, and a straight stretch that is at least 4 miles long, since with this gearing 5th gear acceleration takes a while!
The gearing could be achieved at a reasonable rpm by using a combination of tall rear tires (eg 245/45-18, 26.7" diameter) and the tall 5th gear set from a 1983-1987 US model 944 (0.73:1), which is a direct bolt-in to a 951 tranny. This particular combination would hit 200 mph at 6,400 rpm, which would be a reasonable HP peak for a 951 with improved breathing (big turbo, exhaust, intake/head polishing, etc.)
Building a 951 engine to 380 rwhp@6,400 rpm should be doable, and probably has been done by several tuners. You then need a custom-calibrated speedo a la Dfastest, or a GPS datalogger, since you may not be watching the speedo anyway. Oh, and a straight stretch that is at least 4 miles long, since with this gearing 5th gear acceleration takes a while!
09-12-2003 | 03:26 PM
#49
Addict
Rennlist Member
Rennlist Member
Joined: May 2002
Posts: 3,649
Likes: 0
From: Phoenix, AZ - NJ Runaway
Just last night my neighbor swore that his ZR1 vette did 212mph stock. It wasn't even wort the argument but reading this post made me laugh as it reminded me of his ignorance. I told him if his ZR1 did 212 then his ZO6 must do 250.
09-12-2003 | 04:18 PM
#50
Thread Starter
Drive-by provocation guy
Rennlist Member
Rennlist Member
Joined: Apr 2002
Posts: 10,439
Likes: 0
From: NAS PAX River, by way of Orlando
Very cool water guy!!!
I am sure Tony G will have a rebuttal to that though
Tony???
Also, what is the stock gearing of the 951 in 5th gear??
I am sure Tony G will have a rebuttal to that though
Tony???
Also, what is the stock gearing of the 951 in 5th gear??
09-12-2003 | 04:40 PM
#51
Three Wheelin'
Joined: Aug 2002
Posts: 1,388
Likes: 3
From: Vancouver, BC
Tony has probably been a lot closer to achieving this speed than I will ever get, so I will probably listen to his rebuttal. The physics are fairly straight forward until you get into the important details like aerodynamic stability at that speed. One of the car magazines built up a stock Camaro for a top speed run on the salt flats; unfortunately, it turned out that at 230 mph the Camaro body (no spoilers) was actually more aerodynamic going backwards than forwards, so the car flipped itself around. Great pictures, and the driver actually survived the 17 rollovers without serious injury (good roll cage apparently.)
The stock 5th gear in a 951 is 0.829:1, so you could gain about 11-12% top speed by changing to the 944 5th gear.
The stock 5th gear in a 951 is 0.829:1, so you could gain about 11-12% top speed by changing to the 944 5th gear.
09-12-2003 | 05:08 PM
#52
Rennlist Junkie Forever
Joined: Dec 2001
Posts: 5,978
Likes: 2
From: Los Angeles
951 US Spec
1st. 3.500
2nd. 2.059
3rd. 1.400
4th. 1.034
5th. 0.829
R&P Ratio is 3.375
And.. I'm not rebutting anything. I'm simply stating the rpm facts. It's these facts that make some of the claims difficult to believe in that the rpm needed to attain some of the mph claims are very very high.
1st. 3.500
2nd. 2.059
3rd. 1.400
4th. 1.034
5th. 0.829
R&P Ratio is 3.375
And.. I'm not rebutting anything. I'm simply stating the rpm facts. It's these facts that make some of the claims difficult to believe in that the rpm needed to attain some of the mph claims are very very high.
09-12-2003 | 05:19 PM
#53
Track Day
Joined: Mar 2003
Posts: 21
Likes: 0
From: palo alto, california
Originally posted by 87Porsche951
im gonna throw in my 2 cents but first let me say im not a engineer nor are most of us but i do know for a fact that a Chip set does give you more top end, i think this is because it allows for more RPM's.
I would say that to hit 200MPH you would need more RPM's cause we all know more RPM's equates to more top speed. I mean you cant hit 200MPH if your only getting 1000RPM, but we also all know that the bigger tire can travel a longer distance per revolution than a smaller tire. So that means a 16" tire will have a shorter travle distance per RPM than a 17" tire. so if i am thinking correctly a 17" tire will travel 1" longer per RPM than a 16" tire. so with a larger tire means a little more top speed.
Also the thing about needing power at certain RPMs to hit 200MPH does sound right in theory. I mean if your power drops at 65000 RPM than in theory you wont have enough "Pull" to get you to 200MPH"
I also think you would need to be able to hit around 10,000 RPM to get 200MPH. Which our motor cant handle.
The talk about more power equals more speed is incorrect. Once our cars hit 300hp they have hit there top speed capabilitys. Even if your motor has 1000rwhp you wont have more top speed just get to top speed quicker. Kinda like riding a bike, you get to the point where no matter how much you turn the pedals yo dont go any faster and a bikes sprockets are alot like gearing in a car.
Gear ratio is the only way to get higher top end in my opinion. But with taller gears equals slower exceleration. So more tq is needed for our cars to maintain a decent accelaration.
I have another commment about the thing about power being at certain RPMs. When you do ANY modification to a Engine you affect the cars power band, the power band shifts. Which way it shifts is beyond me.
Even if you had tall enough gearing to hit 200MPH i would think the engine would need to be presicely balanced so it doesnt blow up at the near 10,000 RPM's i would think it needs plus better fuel managment system and needs to be fine tuned to RPMs. cause your gonna need some more fule at higher RPM's to maintain speed.
Also someone suggested to swap 951 tranny with a 968T tranny. well, i had the same idea but was informed that the 968T 6th gear was equal to the 951 5th gear so no change in top speed would bee seen and that you would just be shifting more often.
I also think we need to increase displacement to increase our tq. im talking 2.8L-3.0L and a huge huge turbo thats running like 45-50psi. and building 3.0L Torque monster running 50psi boost and 10,000+rpm's and having it last is very hard.
im gonna throw in my 2 cents but first let me say im not a engineer nor are most of us but i do know for a fact that a Chip set does give you more top end, i think this is because it allows for more RPM's.
I would say that to hit 200MPH you would need more RPM's cause we all know more RPM's equates to more top speed. I mean you cant hit 200MPH if your only getting 1000RPM, but we also all know that the bigger tire can travel a longer distance per revolution than a smaller tire. So that means a 16" tire will have a shorter travle distance per RPM than a 17" tire. so if i am thinking correctly a 17" tire will travel 1" longer per RPM than a 16" tire. so with a larger tire means a little more top speed.
Also the thing about needing power at certain RPMs to hit 200MPH does sound right in theory. I mean if your power drops at 65000 RPM than in theory you wont have enough "Pull" to get you to 200MPH"
I also think you would need to be able to hit around 10,000 RPM to get 200MPH. Which our motor cant handle.
The talk about more power equals more speed is incorrect. Once our cars hit 300hp they have hit there top speed capabilitys. Even if your motor has 1000rwhp you wont have more top speed just get to top speed quicker. Kinda like riding a bike, you get to the point where no matter how much you turn the pedals yo dont go any faster and a bikes sprockets are alot like gearing in a car.
Gear ratio is the only way to get higher top end in my opinion. But with taller gears equals slower exceleration. So more tq is needed for our cars to maintain a decent accelaration.
I have another commment about the thing about power being at certain RPMs. When you do ANY modification to a Engine you affect the cars power band, the power band shifts. Which way it shifts is beyond me.
Even if you had tall enough gearing to hit 200MPH i would think the engine would need to be presicely balanced so it doesnt blow up at the near 10,000 RPM's i would think it needs plus better fuel managment system and needs to be fine tuned to RPMs. cause your gonna need some more fule at higher RPM's to maintain speed.
Also someone suggested to swap 951 tranny with a 968T tranny. well, i had the same idea but was informed that the 968T 6th gear was equal to the 951 5th gear so no change in top speed would bee seen and that you would just be shifting more often.
I also think we need to increase displacement to increase our tq. im talking 2.8L-3.0L and a huge huge turbo thats running like 45-50psi. and building 3.0L Torque monster running 50psi boost and 10,000+rpm's and having it last is very hard.
09-12-2003 | 05:44 PM
#54
Thread Starter
Drive-by provocation guy
Rennlist Member
Rennlist Member
Joined: Apr 2002
Posts: 10,439
Likes: 0
From: NAS PAX River, by way of Orlando
4th. 1.034
5th. 0.829
WOW, not much difference from 4th to 5th. That explains why at highway speeds in 5th, the revs only drop a little bit from 4th to 5th. At least that is what I have noticed.
5th. 0.829
WOW, not much difference from 4th to 5th. That explains why at highway speeds in 5th, the revs only drop a little bit from 4th to 5th. At least that is what I have noticed.
09-12-2003 | 06:36 PM
#55
Rennlist Member
Joined: Apr 2003
Posts: 2,841
Likes: 6
From: Las Vegas NV
Luke, Thanks for the support.
David Floyd, you're right, a gps would settle everything. Wanna sit in the passenger seat and collect data for me?
Danny 951, I'd love to get the taller fifth and squeek past 200. Just don't know if it's worth it. That's pretty fast. I'm not worried about something giving in the motor. It's pretty much bullet proof. But a tire or something in the road. Hope you guys would say something nice at the funeral. hell you guys would probably want to see what's left and available from the car. (chuckle)
Tony G, you may be right. I may have been doing 7200 rpms. If that's the case I don't think I should do that again. I have to run. Going to the German Auto Fest in Ventura California. Hope to see some of you there. My car will be on display at the Powerhaus booth all day Saturday. Take care...
David Floyd, you're right, a gps would settle everything. Wanna sit in the passenger seat and collect data for me?
Danny 951, I'd love to get the taller fifth and squeek past 200. Just don't know if it's worth it. That's pretty fast. I'm not worried about something giving in the motor. It's pretty much bullet proof. But a tire or something in the road. Hope you guys would say something nice at the funeral. hell you guys would probably want to see what's left and available from the car. (chuckle)
Tony G, you may be right. I may have been doing 7200 rpms. If that's the case I don't think I should do that again. I have to run. Going to the German Auto Fest in Ventura California. Hope to see some of you there. My car will be on display at the Powerhaus booth all day Saturday. Take care...
09-12-2003 | 06:48 PM
#56
Addict
Rennlist Member
Rennlist Member
Joined: Dec 2001
Posts: 1,136
Likes: 0
From: socal
Originally posted by gilwong
The only factory production cars over 200 (and just barely) are the Lamborghini Diablo and Murcielago.
The only factory production cars over 200 (and just barely) are the Lamborghini Diablo and Murcielago.
Taken from
http://www.allcars.org/top_lists_topspeed.html
(I included a few under 200 as well)
386.2 kph / 240.0 mph
1997 McLaren F1
354.1 kph / 220.0 mph
2003 Dodge Viper SRT-10 Convertible
330 kph / 205.1 mph
2002 Lamborghini Murcielago
321.9 kph / 200.0 mph
2001 Saleen S7
320.0 kph / 198.8 mph
1999 Lamborghini Diablo SV
315.4 kph / 196.0 mph
2002 Porsche 911 GT2
305.8 kph / 190.0 mph
2002 Aston Martin V12 Vanquish
1997 McLaren F1
354.1 kph / 220.0 mph
2003 Dodge Viper SRT-10 Convertible
330 kph / 205.1 mph
2002 Lamborghini Murcielago
321.9 kph / 200.0 mph
2001 Saleen S7
320.0 kph / 198.8 mph
1999 Lamborghini Diablo SV
315.4 kph / 196.0 mph
2002 Porsche 911 GT2
305.8 kph / 190.0 mph
2002 Aston Martin V12 Vanquish
09-12-2003 | 06:59 PM
#57
Thread Starter
Drive-by provocation guy
Rennlist Member
Rennlist Member
Joined: Apr 2002
Posts: 10,439
Likes: 0
From: NAS PAX River, by way of Orlando
And soon added to the list, the Carrera GT
The Viper did 200??????? Wasn't the SRT-10 the first generation that was not even as fast as the GTS???
The Viper did 200??????? Wasn't the SRT-10 the first generation that was not even as fast as the GTS???
09-13-2003 | 01:32 AM
#58
Instructor
Joined: Mar 2003
Posts: 202
Likes: 0
From: vancouver, canada
Sorry, forgot about the McLaren F1 (top speed title holder until the Bugatti Veyron comes out). But this was a limited edition car with a total of 65 road cars built.
The 220 mph figure for Viper is probably wrong or that car was heavily modified. Road & Track has got the Viper at 195mph.
Road & Track has the 2003 Saleen at 220 mph top speed. The Saleen is also a very limited production road car.
I guess the point is there are maybe only a handful of road cars that exceed 200 mph and any modded 951 that can achieve this milestone would join a very exclusive club.
The 220 mph figure for Viper is probably wrong or that car was heavily modified. Road & Track has got the Viper at 195mph.
Road & Track has the 2003 Saleen at 220 mph top speed. The Saleen is also a very limited production road car.
I guess the point is there are maybe only a handful of road cars that exceed 200 mph and any modded 951 that can achieve this milestone would join a very exclusive club.
09-13-2003 | 04:37 AM
#59
Three Wheelin'
Joined: Feb 2002
Posts: 1,493
Likes: 0
From: Arlington, TX
is the 5th gear in a 944 (83-87) an overdrive?
honestly, I've always wondered what makes an overdrive an overdrive. i know i've read that like in the 968, the 5th and 6th gears are "still not overdrive gears" but not sure what that means...
someone enlighten me
honestly, I've always wondered what makes an overdrive an overdrive. i know i've read that like in the 968, the 5th and 6th gears are "still not overdrive gears" but not sure what that means...
someone enlighten me
09-13-2003 | 06:57 AM
#60
6th Gear
Joined: Nov 2002
Posts: 6
Likes: 0
From: Madrid
Originally posted by TonyG
951 US Spec
1st. 3.500
2nd. 2.059
3rd. 1.400
4th. 1.034
5th. 0.829
R&P Ratio is 3.375
951 US Spec
1st. 3.500
2nd. 2.059
3rd. 1.400
4th. 1.034
5th. 0.829
R&P Ratio is 3.375
For those who want to check their car's speed, try this page :
http://www.peb951.net/42-demultinteract.html (it's in french
)You can change gears, tire's size and RPM and you obtain the speed in km/h or in miles/hour (if you indicate 1.609344 in the specific cell).
With 245/45/16 - 200 mph is reached at 7678 rpm
With 285/35/18 - 200 mph is reached at 7329 rpm
But you'll need more power than stock.....
Peb