Low Top speeds
Discussion
Been reading up on the old Yank cars which have very big power and was surprised to see that most of their top speeds are 120mph yet pushing out 400bhp! These are 3 speed auto or "4 on the floor". Are these cars limited electronically to these speeds OR is it the gearing that is the restriction?
I would have thought that if its gearing then in 4th gear you'd be pulling 5000rpm (peak power) at 120mph so that gives a mph/'000 rpm of 24mph thus at 70mph your doing around 3000rpm... assuming a linear power output that would be roughly 300bhp to sustain 70mph!
Im guessing they must be electronically limited as why else would these monster muscle cars need to be reving so highly at such low speeds?
I would have thought that if its gearing then in 4th gear you'd be pulling 5000rpm (peak power) at 120mph so that gives a mph/'000 rpm of 24mph thus at 70mph your doing around 3000rpm... assuming a linear power output that would be roughly 300bhp to sustain 70mph!
Im guessing they must be electronically limited as why else would these monster muscle cars need to be reving so highly at such low speeds?
When I 1st got my Camaro had a 3 speed auto, top speed was about 120 at 5000rpm.
Back then acceleration was more important, more sedate saloons ran higher gearing in the diff so would cruise better.
Since fitting a 4speed lock up auto, much nicer on the motorway. Therotically 5000rpm would be 160 but can't tell at what point aerodynamics are the limiting factor, as at 140mph it gets more than a bit scary
Must upgrade the brakes one day
Back then acceleration was more important, more sedate saloons ran higher gearing in the diff so would cruise better.
Since fitting a 4speed lock up auto, much nicer on the motorway. Therotically 5000rpm would be 160 but can't tell at what point aerodynamics are the limiting factor, as at 140mph it gets more than a bit scary
Must upgrade the brakes one day
They were generally geared to peak at that speed as they were not only dangerous above that but the tyre technology of the time couldn't sustain a 3500lb car at those speeds. Many still ran on high profile crossplies before radials became the norm and long before teflon and yre stiffening technology made high speed sustainable. Brakes were also weak and the gears tended to be widely spaced 3 speed autos and low-geared back axles. Since they did about 10mpg round town, you can imagine what they did at 120 with not so much aerodyamics as cow-catching nacelles on the front.
It just seems odd from a modern era perspective where a run of the mill say Skoda Fabia vRS with 130bhp TDI can do 130mph thus given a long enough straight to catchup after the 0-120mph blast of the muscle car it would win....
Do owners of such classics keep them as concours condition i.e. no modification and keep the factory spec tyre & gearing or is it generally changed?
Do owners of such classics keep them as concours condition i.e. no modification and keep the factory spec tyre & gearing or is it generally changed?
In America, stock is very much in - anything stock is a collector's car and often worth a lot of money. If you look up Bloomington Gold, you'll find a concours Corvette Show that makes anal a term of casual indifference. In the UK, most cars are generally modified but again this will depend upon rarity and whether the car is an original "numbers matching" (chassis and engine) car. Surrey Muscle certainly mod their cars and race them and the burnout competition is a good indicator of the power they chuck out.
Given that a emision-strangled 1977 6.6 litre Trans Am only put out a fairly paltry bhp total and hit 60 in 9.9 due to low compression engines, most of this era cars tended to be modified. It's perfectly feasible to turn your 140bhp smogger into a 400hp car with the right parts.
Modern cars can and will out-peform older muscle cars in stock form but there is so much more to it than that. For example, most modern cars produce their maximum power and torque at the top end so have to be worked hard to extract the performance whereas a muscle car has buckets of wheel-spinning torque right across the range and that's all part of the driving experience. You can't really compare the dull efficiency of a FWD Skoda with a tyre-smoking, tail-snaking, V8-roaring Hollywood take-off.
There's more to it than headline bhp power though. I once tested a 5.0 1986 Trans Am which produced 140bhp. It still felt amazingly powerful as did the 170hp 1987 Camaro Z28 I eventually bought. You can't really describe it, it's like a very deep pit of rumbling, creamy power that surges like a wave rather than like a smaller motor spinning like a drill. It's not how fast you get there, it's how you get there.
Given that a emision-strangled 1977 6.6 litre Trans Am only put out a fairly paltry bhp total and hit 60 in 9.9 due to low compression engines, most of this era cars tended to be modified. It's perfectly feasible to turn your 140bhp smogger into a 400hp car with the right parts.
Modern cars can and will out-peform older muscle cars in stock form but there is so much more to it than that. For example, most modern cars produce their maximum power and torque at the top end so have to be worked hard to extract the performance whereas a muscle car has buckets of wheel-spinning torque right across the range and that's all part of the driving experience. You can't really compare the dull efficiency of a FWD Skoda with a tyre-smoking, tail-snaking, V8-roaring Hollywood take-off.
There's more to it than headline bhp power though. I once tested a 5.0 1986 Trans Am which produced 140bhp. It still felt amazingly powerful as did the 170hp 1987 Camaro Z28 I eventually bought. You can't really describe it, it's like a very deep pit of rumbling, creamy power that surges like a wave rather than like a smaller motor spinning like a drill. It's not how fast you get there, it's how you get there.
Noise aside is the current x35d BMW engines the closest thing to big block power delivery?
Just seen a Stingray online wow.
I also had the great pleasure of seeing a concours AC Cobra 427 in normal blue & white strips. Started up sounded stunning, engine off looked the most erotic/desirable car Ive ever seen.. Looked amazing.
Just seen a Stingray online wow.
I also had the great pleasure of seeing a concours AC Cobra 427 in normal blue & white strips. Started up sounded stunning, engine off looked the most erotic/desirable car Ive ever seen.. Looked amazing.
I've never driven a diesel 335d nor will I ever drive one. I imagine it still sounds like a taxi or is too quiet. I just don't like diesel engine characteristics - very narrow power bands.
I was never into American cars and wanted a Porsche 928 which I test drove. It was quick, had 300hp, was loud in a clinical way and it was bring. I driove a 1985 Corvette and it was a "shining revelation" moment from the instant the car fired into life and echoed like an angry cannon off the walls of adjoining houses. Car alarms activated. The car shook and rocked and repeatedly snarled at the still air. Slipping it into Drive, the car just felt like it was alive, like riding a rhino. The whole car resonated with the drone from the exhaust and when you floored it, the noise made you laugh.
So is it like a BMW? Er. No.
Certainly on older American V8s, all the power is "instant" and low down and they only run out of breath at the top end. I think I can best describe it as being relentlessly powerful - there is simply no gap in the power band where you wonder where the power went. Funnily enough, I've found that as American V8s have got more powerful and rev higher, this is less true and you do note comparatively less power lower down
I was never into American cars and wanted a Porsche 928 which I test drove. It was quick, had 300hp, was loud in a clinical way and it was bring. I driove a 1985 Corvette and it was a "shining revelation" moment from the instant the car fired into life and echoed like an angry cannon off the walls of adjoining houses. Car alarms activated. The car shook and rocked and repeatedly snarled at the still air. Slipping it into Drive, the car just felt like it was alive, like riding a rhino. The whole car resonated with the drone from the exhaust and when you floored it, the noise made you laugh.
So is it like a BMW? Er. No.
Certainly on older American V8s, all the power is "instant" and low down and they only run out of breath at the top end. I think I can best describe it as being relentlessly powerful - there is simply no gap in the power band where you wonder where the power went. Funnily enough, I've found that as American V8s have got more powerful and rev higher, this is less true and you do note comparatively less power lower down
Edited by LuS1fer on Thursday 13th November 19:42
It's all about the gearing, most American cars didn't have any overdrive gear until the mid 80's, and were set up for accelration... 55mph was highway cruising speed so top speed didn't matter...
I used to have a 3 speed auto also, but now i've got an overdrive 5 speed manual in mine and with my 2.56 rear gears it 'should' do about 230mph... !
(it's massively unlikely as aerodynamics will be a huge factor)
I used to have a 3 speed auto also, but now i've got an overdrive 5 speed manual in mine and with my 2.56 rear gears it 'should' do about 230mph... !
(it's massively unlikely as aerodynamics will be a huge factor)
Probably the biggest factor is the gearing then combined with the rear diff ratio can seriously limit top end.
That said my 351 cleveland 3 spd Torino (3.00:1 rear diff shouldn't be that great for acceleration) will trounce just about anything up to about 100mph (including my Monaro - a modern 350ci with 6 gears and a 3.46:1 rear diff) but will also go well clear of the end of the 120mph speedo (sat nav had me doing 146mph one time).
So in short I don't know!!! LOL
That said my 351 cleveland 3 spd Torino (3.00:1 rear diff shouldn't be that great for acceleration) will trounce just about anything up to about 100mph (including my Monaro - a modern 350ci with 6 gears and a 3.46:1 rear diff) but will also go well clear of the end of the 120mph speedo (sat nav had me doing 146mph one time).
So in short I don't know!!! LOL
LuS1fer said:
Certainly on older American V8s, all the power is "instant" and low down and they only run out of breath at the top end. I think I can best describe it as being relentlessly powerful - there is simply no gap in the power band where you wonder where the power went. Funnily enough, I've found that as American V8s have got more powerful and rev higher, this is less true and you do note comparatively less power lower down
That is the most accurate thing I've read RE: Old vs New Yank V8's.I had exactly the same thoughts in my head but you've managed to put it into words perfectly.
jayrockwell said:
^ Are you following me? LOL
Oooooooh sweet a 68 Firebird! Please tell me it's got the 400ci lump....please.....
That will SHIFT given your penchant for mods
It`s a 350/350 with an open diff at the mo, looking to go 454/400 with a locker.Oooooooh sweet a 68 Firebird! Please tell me it's got the 400ci lump....please.....
That will SHIFT given your penchant for mods
Always scanning this site (Don`t forget I have Mental Betty as MY summer ride)
jayrockwell said:
Mental Betty???
What's Mental Betty?
Quite well known in the HSV forum, done a dyno day and a Drag day with her (15.1@94mph)What's Mental Betty?
Check her out on my profile, sorry can`t post photos yet.
Edited by crisisjez on Tuesday 25th November 18:46
Edited by crisisjez on Tuesday 25th November 18:48
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