# 320kph in an R32 = how many hp?



## kismetcapitan (Nov 25, 2005)

how much horsepower does it take to push an R32 to 200mph (320kph)? anyone ever take their R32 up to that speed? How were the aerodynamics? I'm thinking a front diffuser to increase downforce on the front wheels may not be a bad idea...


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## shadowninja (Sep 29, 2002)

Doesn't downforce increase drag?


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## skykit (Apr 14, 2006)

600+bhp should see you at the magic figure if you have a long enough road


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## leggus (Feb 15, 2006)

skykit said:


> 600+bhp should see you at the magic figure if you have a long enough road



And a six speed gearbox


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## m6beg (Apr 21, 2003)

And a load and load of ££££££££££££££££££££££££

hahahahahahahah:wavey: :wavey: :wavey: :wavey: 


Mick


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## kismetcapitan (Nov 25, 2005)

leggus said:


> And a six speed gearbox


a six-speed won't do squat, as the final cog for every set I've seen is the same ratio as the fifth gear in a standard box - six gears just gives more shifting ratios between 1st and the top gear, and basically would make a car with a narrow powerband a bit more flexible.

Yeah, a front diffuser would increase downforce and drag, but stability at that speed is also pretty important. I'm interested in hearing first hand experiences of people who've taken R32s up into the 200mph zone.


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## leggus (Feb 15, 2006)

kismetcapitan said:


> a six-speed won't do squat, as the final cog for every set I've seen is the same ratio as the fifth gear in a standard box - six gears just gives more shifting ratios between 1st and the top gear, and basically would make a car with a narrow powerband a bit more flexible.


Oh?

I thought six speed box like in the R34 had a longer top gear, my R32 is screaming its nuts off in fifth gear at 170 mph.

If its gotta rev another couple or three thousand RPM to reach the magic number then big dough would need to be spent methinx....


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## kismetcapitan (Nov 25, 2005)

leggus said:


> Oh?
> 
> I thought six speed box like in the R34 had a longer top gear, my R32 is screaming its nuts off in fifth gear at 170 mph.
> 
> If its gotta rev another couple or three thousand RPM to reach the magic number then big dough would need to be spent methinx....


interesting, so the R32 has a gear-limited top speed of 170mph? What's your rpm at that point, is it around 8K?

You've got a point though, I'd never spend a dime on a six-speed unless that meant having a longer top gear - all the better for a higher top speed and also maybe better fuel economy on the highway.


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## R33_GTS-t (Apr 27, 2005)

kismetcapitan said:


> interesting, so the R32 has a gear-limited top speed of 170mph? What's your rpm at that point, is it around 8K?
> 
> You've got a point though, I'd never spend a dime on a six-speed unless that meant having a longer top gear - all the better for a higher top speed and also maybe better fuel economy on the highway.


The R34 6sp does 27mph/1000rpm in top with 18 inch wheels. The R32 does 23.9mph/1000rpm in top with 16 inch wheels. The R32 will do more than 170mph with the stock 5sp, trust me. The rev limit is 8200rpm, so it should theoretically make 196mph (+ some mph for tyre expansion) with 16 inch wheels.

Power = Force * Velocity = 0.5 * Air Density * Drag Coefficient * Cross-sectional Area * Velocity^3

Assume Cross-sectional Area ~ 2m^2
Drag Coefficient = 0.4
Velocity = 200mph = 88.89m/s
Assume Air Density ~ 1.225kg/m^3

Power = 0.5 * 1.225 * 0.4 * 2 * (88.89^3) = 344,156W = 344.156kW = [email protected] (not hubs)

Assume 25% loss between flywheel and wheels for 4WD, so add 1/3 (75 + 33% = 100), giving:

1.333 * 461 = *615bhp*

If Cross-sectional Area is 1.8m^2 this falls to about 550bhp.


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## R33_GTS-t (Apr 27, 2005)

m6beg said:


> And a load and load of ££££££££££££££££££££££££


Especially if you ask _5th Gear_ to do it for you.:chuckle: :chuckle:


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## kismetcapitan (Nov 25, 2005)

well, that explains that  thanks for the math, I can now see how running bigger diameter wheels can make a difference. But I don't I can add that extra inch (255/40R17 to 255/40R18)...because off the line acceleration will be equally geared up. Reachable with stock diameter wheels though, that sounds good.


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## R33_GTS-t (Apr 27, 2005)

kismetcapitan said:


> well, that explains that  thanks for the math, I can now see how running bigger diameter wheels can make a difference. But I don't I can add that extra inch (255/40R17 to 255/40R18)...because off the line acceleration will be equally geared up. Reachable with stock diameter wheels though, that sounds good.


Stock wheels do mean stock/small brakes due to space constraints. I wouldn't like to have to stop from 200mph with stock brakes.:flame::runaway::flame:


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## psd1 (May 15, 2004)

Just like everything there's more than just the math...I havent heard of alot of R32's hitting the magic 320...I'm gonna guess more like 700+ HP...of course your own abandoned airfield or sunday morning stretch of Autobahn to get there too...


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## R33_GTS-t (Apr 27, 2005)

700bhp is overkill. 700bhp got the X5 Le Mans up to 194mph and that's a bloody SUV.


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## GTR RGT (Aug 29, 2006)

R33_GTS-t said:


> The R34 6sp does 27mph/1000rpm in top with 18 inch wheels. The R32 does 23.9mph/1000rpm in top with 16 inch wheels. The R32 will do more than 170mph with the stock 5sp, trust me. The rev limit is 8200rpm, so it should theoretically make 196mph (+ some mph for tyre expansion) with 16 inch wheels.
> 
> Power = Force * Velocity = 0.5 * Air Density * Drag Coefficient * Cross-sectional Area * Velocity^3
> 
> ...


Im lost back here :runaway:


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## daytona (Jun 28, 2005)

Hi
On topic, anyone know the speeds in 5th gear at say 6000, 7000, 8000 on standard R32GTR


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## m6beg (Apr 21, 2003)

daytona said:


> Hi
> On topic, anyone know the speeds in 5th gear at say 6000, 7000, 8000 on standard R32GTR


I got a dyno sheet out here for you:wavey: :wavey: 

My 32 done 128 mph @7512 rpm in fourth.

Mick


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## leggus (Feb 15, 2006)

daytona said:


> Hi
> On topic, anyone know the speeds in 5th gear at say 6000, 7000, 8000 on standard R32GTR


Difficult to look at those speeds.. tunnel vision comes into the equation, redline is 170 on the clock in my car..thats 7500 rpm

All depending on the accuracy of the clock of course.

8250 rpm which it would have pulled to if there wasnt an artic lorry 500 yards ahead remains to be seen.. the A38 is a good place most of the time


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## R33_GTS-t (Apr 27, 2005)

daytona said:


> Hi
> On topic, anyone know the speeds in 5th gear at say 6000, 7000, 8000 on standard R32GTR


Are we talking indicated or actual speeds and revs? The R32 rev counter over-reads by ~7%.


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## leggus (Feb 15, 2006)

m6beg said:


> I got a dyno sheet out here for you:wavey: :wavey:
> 
> My 32 done 128 mph @7512 rpm in fourth.
> 
> Mick


My 32 did 139.7 @ 7944 rpm


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## R33_GTS-t (Apr 27, 2005)

m6beg said:


> I got a dyno sheet out here for you:wavey: :wavey:
> 
> My 32 done 128 mph @7512 rpm in fourth.
> 
> Mick


What size wheels? The stock transmission is supposed to give 17.9mph/1000rpm in 4th with 16s. Was that actual or indicated rpm?


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## leggus (Feb 15, 2006)

R33_GTS-t said:


> What size wheels? The stock transmission is supposed to give 17.9mph/1000rpm in 4th with 16s. Was that actual or indicated rpm?


wheel size is irrelevant depending on tyre profile, my 16's have bigger tyres so rolling radius is the same as 17's with low profiles


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## tweenierob (Aug 5, 2003)

I needed 700+ to reach 200 at brunters, on my private road i found at around 600ish anything over 185 was a struggle.

Rob


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## m6beg (Apr 21, 2003)

R33_GTS-t said:


> What size wheels? The stock transmission is supposed to give 17.9mph/1000rpm in 4th with 16s. Was that actual or indicated rpm?


No that was on the dyno.

Mick


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## m6beg (Apr 21, 2003)

No wheels :squintdan :squintdan :squintdan


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## JapFreak786 (Aug 29, 2003)

seen a R32 GTR with approx 600bhp do over 200mph


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## m6beg (Apr 21, 2003)

It is very very hard to get to the magic 200 mph.

Mick


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## m6beg (Apr 21, 2003)

JapFreak786 said:


> seen a R32 GTR with approx 600bhp do over 200mph


With what gear box???

Mick


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## R33_GTS-t (Apr 27, 2005)

600bhp is still a lot for 200mph. Cars like the F40 made do with 478bhp. With 4-5 miles of motorway and the right gearing/power curve, 600(ish)bhp would do it.


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## kismetcapitan (Nov 25, 2005)

tweenierob said:


> I needed 700+ to reach 200 at brunters, on my private road i found at around 600ish anything over 185 was a struggle.
> 
> Rob


how stable was the car at those speeds? did it feel like anything was lifting, feeling light?


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## Steve (Sep 21, 2001)

*Just for info purpose*

Have achieved 186mph (GPS Road Angle) in standard trim (except Do Luck fron bumper) in my R33 GT-R with 550bhp / 420lbs ft torque and she was steadier than I was !!!!


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## psd1 (May 15, 2004)

tweenierob said:


> I needed 700+ to reach 200 at brunters, on my private road i found at around 600ish anything over 185 was a struggle.
> 
> Rob


OOoohhh, dont tell rain man, err R33 GTS-t that....I'm sure it was your driving! :squintdan


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## tweenierob (Aug 5, 2003)

On Standard suspension the car got very out of shape on braking, i didnt attempt a 2nd top speed run because of it.

On my private road at around 600hp (3mile straight) the car seemed to hit a flat spot at 185, it was still making the right noises but really struggled to pull to 187 so i backed off. Deffo wasnt a drop in power.

Rob


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## psd1 (May 15, 2004)

tweenierob said:


> On Standard suspension the car got very out of shape on braking, i didnt attempt a 2nd top speed run because of it.
> 
> Rob


Yikes...one of the times when you wished you had a 3 mile coast down too!!!


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## R33_GTS-t (Apr 27, 2005)

psd1 said:


> OOoohhh, dont tell rain man, err R33 GTS-t that....I'm sure it was your driving! :squintdan


It must be. I made a TOM-TOM GPS 180mph with 0.9bar on stock turbos. I'm sure that with an extra 33+% power, I can make 11% more speed. Just a matter of distance. Fortunately I own a private motorway, so distance is not a problem.

Tweenie - What rpm is your power peak at? What mph/1000rpm in top?


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## tweenierob (Aug 5, 2003)

Peak power on that car was 9350rpm.
Unsure of mph per rpm in top, std 32gtr ratio's.

Rob


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## bomberGTR (Dec 3, 2005)

daytona said:


> Hi
> On topic, anyone know the speeds in 5th gear at say 6000, 7000, 8000 on standard R32GTR


my R32 GTR with fairly standard engine did 140mph at 5500rpm last night (on my private runway of course) but i pu$$ied out as death isnt on my list of things to do before my 22nd birthday

felt very stable though with 18"rims and HKS suspension. oh, and no power steering lol


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## MartinC (Jan 1, 2006)

160/170 ish on the speedo with some left in 5th. Had I got bigger balls then I would have gone all the way to the limiter in 5th, So I don't see any problem with 200mph given a long enough road.


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## R33_GTS-t (Apr 27, 2005)

tweenierob said:


> Peak power on that car was 9350rpm.
> Unsure of mph per rpm in top, std 32gtr ratio's.
> 
> Rob


My calculation was based on the 615bhp peak arriving at the rpm that corresponds to 200mph in top. If it's after or before, then you'll need more power. I.e. calculation assumes optimal gearing for top speed.

With standard R32 GTR ratios and wheels, 9350rpm equates to 223mph(+ tyre expansion), so you'd be nowhere near peak power coming up to 200mph. Gearing was too long. Reduce the top gear by ~11% to 21.4mph/1000rpm and you're there.


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## kismetcapitan (Nov 25, 2005)

MartinC said:


> 160/170 ish on the speedo with some left in 5th. Had I got bigger balls then I would have gone all the way to the limiter in 5th, So I don't see any problem with 200mph given a long enough road.


whats your car's spec?


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## tweenierob (Aug 5, 2003)

The car was on 18's with 255 35 18 tyres, highest peak datalogged rpm is 9036rpm but may have been in 4th. May try some top speed runs when i go to elvington next year in the new car, but once again not sure of the hks 6 speed mph/rpm numbers. 

Rob


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## tweenierob (Aug 5, 2003)

IIRC, Martins car is a 33gtr running a chip he put together... Maybe decat.

Rob


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## skyline69_uk (Jan 6, 2005)

You should be aware that published top speeds for production cars are usually made on a racing bowl (e.g. Nardo) over several miles and not on a stretch of runway so getting to 200mph on a 1 to 2 mile straight is well beyond most(not all  ) of those supercars also.

Aerodynamics is a VERY big factor at those speed and you could achieve a far better top speed by setting the CDA factor up to be lower than just adding horsepower alone.


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## R33_GTS-t (Apr 27, 2005)

tweenierob said:


> The car was on 18's with 255 35 18 tyres, highest peak datalogged rpm is 9036rpm but may have been in 4th. May try some top speed runs when i go to elvington next year in the new car, but once again not sure of the hks 6 speed mph/rpm numbers.
> 
> Rob


Whatever your gearing, ideally you need 9350rpm (peak power) in 6th to correspond to 200mph, if you want to hit it with the minimum bhp necessary.

Sounds like one hell of an engine anyway. Is it a 2.6, 2.7 or 2.8 out of curiosity?


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## R33_GTS-t (Apr 27, 2005)

skyline69_uk said:


> You should be aware that published top speeds for production cars are usually made on a racing bowl (e.g. Nardo) over several miles and not on a stretch of runway so getting to 200mph on a 1 to 2 mile straight is well beyond most(not all  ) of those supercars also.


True but you do get tyre scrubbing on bowls. Ideally you need something like Ehra Lessien (VW test track used for MaClaren F1 240mph run). A 150mph banked corner followed by 6 miles of straight then another 150mph banked corner.


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## skyline69_uk (Jan 6, 2005)

R33_GTS-t said:


> True but you do get tyre scrubbing on bowls. Ideally you need something like Ehra Lessien (VW test track used for MaClaren F1 240mph run). A 150mph banked corner followed by 6 miles of straight then another 150mph banked corner.


That would be ideal! I think what people also miss is the fact that top speed and acceleration are not connected so a car can do 200mph given enough room but still only accelerate like a Lada!


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## R33_GTS-t (Apr 27, 2005)

skyline69_uk said:


> That would be ideal! I think what people also miss is the fact that top speed and acceleration are not connected so a car can do 200mph given enough room but still only accelerate like a Lada!


I hope you're not poking fun at the Bentley GT and Silver Spur.


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## skyline69_uk (Jan 6, 2005)

R33_GTS-t said:


> I hope you're not poking fun at the Bentley GT and Silver Spur.


That's spooky because in past posts I used the Bentley as an example of just that thing lol.


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## R33_GTS-t (Apr 27, 2005)

skyline69_uk said:


> That's spooky because in past posts I used the Bentley as an example of just that thing lol.


2.4 tonnes, lower torque than bhp, 230hp/ton. It was an obvious candidate.


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## tweenierob (Aug 5, 2003)

My present car does not have peak power at 9350, that was the last car.
New one is being put together over the winter, 2.6 this time, hopefully rev over 10k if it still making power there (which i hope it should be).

Its all about the weight 

Rob


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## Philip (Jan 17, 2002)

tweenierob said:


> Its all about the weight


The weight of what?

Top speed isn't influenced by vehicle weight.

Phil


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## gtr mart (Mar 29, 2004)

this question did come up a few years ago, before so many people had cars that could / had done 200

http://www.gtr.co.uk/forum/upload/32014-what-bhp-cracking-200mph-has-any-one-here-managed.html

mart


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## tweenierob (Aug 5, 2003)

Very true Phil, but accelerating to 200mph in sufficient distance has lots to do with it. 

Rob


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## Philip (Jan 17, 2002)

tweenierob said:


> Very true Phil, but accelerating to 200mph in sufficient distance has lots to do with it.
> 
> Rob


Agreed ...

Phil


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## kismetcapitan (Nov 25, 2005)

isn't it at top speed that an engine would see it's greatest stress? Sustained rpms in the 7-8000 range while pushing a lot of weight in terms of lots of massive air resistance, it seems to me that no other condition would put as much stress on an engine than those conditions. I blew my engine (on bad gas), but it had been running fine on the low octane crap (I didn't know better) and only melted the #6 piston when I was testing top speed (260kph and climbing when the car died).


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## R33_GTS-t (Apr 27, 2005)

kismetcapitan said:


> isn't it at top speed that an engine would see it's greatest stress? Sustained rpms in the 7-8000 range while pushing a lot of weight in terms of lots of massive air resistance, it seems to me that no other condition would put as much stress on an engine than those conditions. I blew my engine (on bad gas), but it had been running fine on the low octane crap (I didn't know better) and only melted the #6 piston when I was testing top speed (260kph and climbing when the car died).


Yep, this is why many people developed pessimistic views of RB26DETT capabilities after the Nismo tests that saw 9 of 10 standard engines fail at 500bhp.

They were tested at that output for several hours on a bench. This is equivalent to maxing out a 500bhp GTR and holding it there for a few hours. The tests are unrepeatable in reality because:

1) Not enough straight road in the UK.
2) Not enough fuel tank capacity.

It's the sustained inertial load on the conrods (and heat) that's the killer.


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## silverbullet (Nov 4, 2006)

did 150mph on canadian highway...got scared. slowed down. Could have gone faster doing only bout 6000rpm. I dont thing im exagerating either. lovin my r32


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