Removal of Catalysts
Discussion
quote:
TVR are not alone in this, most companies exaggerate their output claims also larger companies test loads of engines in lab conditions and nail the best ones figures to the board for the ad campaigns. How bhp is measured is another variable you do not want to become embroiled in......but probably will, I did
Just because other companies do it, it doesn't make it right. Lets rise above these yanks, germans and japs, we are after all British. If they can get it right for the Cerb 4.2 why can't they get it right for all TVRs. Just tell it like it is and people will respect that, try and mislead and people will not want to know.
Ok, I'll get me coat.
Edited by Finston on Wednesday 17th October 11:30
quote:
I recall that when Thames Valley got a bunch of cars on a rolling road Steve told me that the 500s had around 201 at the wheels (I said "what?!" - he said "that's pretty good") and that the cerbera 4.2s had 230 - so not that much difference between the two in terms of delivery
Autocar tested the Cerb 4.2 when it was launched and it banged out 349BHP at the rear wheels,
Im gonna get my Griff 500 tested, anybody know how much it costs and where's best, I'm in Chester.
Autocar's Cerb 4.2 test was 349bhp at the flywheel, not the rear wheels. I'd suspect that transmission losses of at least 25%, maybe more, would bring this down to nearer 250bhp at the rear wheels.
And who says it was a standard 4.2... ;-)
Pete
Edited by pete on Monday 22 October 13:03
And who says it was a standard 4.2... ;-)
Pete
Edited by pete on Monday 22 October 13:03
quote:
Autocar's Cerb 4.2 test was 349bhp at the flywheel, not the rear wheels. I'd suspect that transmission losses of at least 25%, maybe more, would bring this down to nearer 250bhp at the rear wheels.
And who says it was a standard 4.2... ;-)
Pete
Edited by pete on Monday 22 October 13:03
No it was a rolling road test. I'll give you more details on the test when I pick the mag up, its at home.
Mark and his Griff 500.
quote:
No it was a rolling road test. I'll give you more details on the test when I pick the mag up, its at home.
Sorry, I should have made myself clearer. They ran a dynamometer test, which you're probably correct in saying was on a rolling road - I can't imagine them taking the engine out of the cerb and sticking it on a test bench. However the figure published included correction factors for transmission losses, and hence is an estimate for power at the flywheel, not at the wheels.
Fortunately it's not as simplistic as using an empirical correction factor; there are methods of measuring transmission losses using a rolling road, although they're not 100% accurate.
Pete
Hi pete,
How did you come across this inside info, I,ve spoken to many people who say the 4.2 Cerb does bang out about 350BHP at the back wheels on the rolling road. Its only the rover V8 and Cerb4.5 which is down on what TVR claim.
Anyway Autocar say "In line with our new policy to dynamometer test all serious performance cars, we put the Cerb 4.2 on a rolling road to verify TVR's claimed outputs of 350BHP at 6500rpm and 320lb of torque at 4500rpm. The results were accurate to within a single horsepower and one pound foot of torque." It went on to say "A standard Lamborghini Diablo or 911 Turbo wouldn't stand a chance of staying with it"
But this is the best bit " First its a great looking car- not so gorgeous, perhaps, as the Griffith but a world ahead of the Chimaera upon whose basic lines it so improves"
Mark and his gorgeous Griff 500
How did you come across this inside info, I,ve spoken to many people who say the 4.2 Cerb does bang out about 350BHP at the back wheels on the rolling road. Its only the rover V8 and Cerb4.5 which is down on what TVR claim.
Anyway Autocar say "In line with our new policy to dynamometer test all serious performance cars, we put the Cerb 4.2 on a rolling road to verify TVR's claimed outputs of 350BHP at 6500rpm and 320lb of torque at 4500rpm. The results were accurate to within a single horsepower and one pound foot of torque." It went on to say "A standard Lamborghini Diablo or 911 Turbo wouldn't stand a chance of staying with it"
But this is the best bit " First its a great looking car- not so gorgeous, perhaps, as the Griffith but a world ahead of the Chimaera upon whose basic lines it so improves"
Mark and his gorgeous Griff 500
I've had a E-Mail from Mark Adams about my Griffs BHP. He says the normal range for a Griff 500 is about 250-265BHP and 300lb/ft of torque. He also says its beneficial to remove the pre cats but not the main cat. He goes on to say that Sprint are doing a review of exhaust manifolds and systems soon so don't rush in just yet because there are some surprises to come.
His basic recommeded modifications.
Replacement of manifolds(removes pre cats)
Reprogramming Engine Management
Larger airflow meter
Carbon Fibre plenum and trumpets
This could bang out 300BHP and 320lb/ft of torque on a good car.
Sounds good to me.
Edited by Finston on Saturday 27th October 11:14
His basic recommeded modifications.
Replacement of manifolds(removes pre cats)
Reprogramming Engine Management
Larger airflow meter
Carbon Fibre plenum and trumpets
This could bang out 300BHP and 320lb/ft of torque on a good car.
Sounds good to me.
Edited by Finston on Saturday 27th October 11:14
quote:
I've had a E-Mail from Mark Adams about my Griffs BHP. He says the normal range for a Griff 500 is about 250-265BHP and 300lb/ft of torque. He also says its beneficial to remove the pre cats but not the main cat. He goes on to say that Sprint are doing a review of exhaust manifolds and systems soon so don't rush in just yet because there are some surprises to come.
His basic recommeded modifications.
Replacement of manifolds(removes pre cats)
Reprogramming Engine Management
Larger airflow meter
Carbon Fibre plenum and trumpets
This could bang out 300BHP and 320lb/ft of torque on a good car.
My current Griff 500 has had this treatment along with a slightly modded cam shaft change and yes went to 300 bhp etc. Also did this to my 390 and went from 226 to over 250 (can't give absolute figures as the back wheels were spinning on the rolling road despite a burly mechanic or two in the boot. The power curves and descriptions are up on the Tower View web site www.t-v-r-services.co.uk in the engine upgrades section if you are interested.
Steve
www.tvrbooks.co.uk
Interesting topic this one. Tbh I was under the impression that noone ever did figures at the wheels. I think all commercial performance figures are at the flywheel and that all manufacturers do it. Obviously some cars will lose less on the way to the tarmac than others but basically it is a consistent and comparable advertising tool.
Ferrari were always optimistic, most figures given in 60's to 80's were simple calculations. For example 365GTB4 (Daytona) was 4.4l, multiply by 80 bhp/litre to arrive at quoted 352. In reality they were around 310. In cars with in excess of 200bhp, the real figure is pretty irrelevant, comparitive performance is more important, this takes into account weight, dynamics etc.
Quoted BHP figures are ALWAYS flywheel horsepower..... rear wheel horsepower is usually well spelled-out because if you simply publish it as "bhp" without explicitly stating that it's at the rear wheels then you're making it very hard for your marketing department when comparing stats to your competition! Basically from what I can gather, a Griff 500 is 250-260bhp at the flywheel which would equate to about 200bhp at the rear wheels.... that's pretty damned respectable really. When you compare that with the MEASURED outputs from most rice burners and look at the torque curves etc it's so easy to see why a 260bhp Griffith will outgun any 280bhp Mitsubishi Evo etc.
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