Discussion
I've been interested by the commonly known 'fact' that the TVR V8s push out a lost less BHP than stated by TVR. For example, the 4.5 engine is rated at 285 BHP (flywheel) but in reality gives somewhere in the region of 240->250 BHP? My understanding is that this engine is derived from the 4.6 engine used in the Range Rover, which is quoted as delivering 225 BHP. What tweaks do TVR carry out on this engine to gain the extra 15->25 BHP and if they are fairly major tweaks, why only a small gain?
TVR would probably argue that the car isn't eaxctly slow so why worry about the power figure?
The mods TVR power in coventry do tend to be a higher lift / longer duration cam, and slightly ported cylinder heads sometimes with bigger valves, depending on spec.
Other mods by the factory can also include bigger / shorter intake pipes, raised compression and a bigger throttle body. Also every capacity varient going 3.5,3.9,4.0 4.2, 4.3, 4.5 5.0 , 5.3......
Bear in mind there is no such thing as a 'standard' TVR.
Matt
The mods TVR power in coventry do tend to be a higher lift / longer duration cam, and slightly ported cylinder heads sometimes with bigger valves, depending on spec.
Other mods by the factory can also include bigger / shorter intake pipes, raised compression and a bigger throttle body. Also every capacity varient going 3.5,3.9,4.0 4.2, 4.3, 4.5 5.0 , 5.3......
Bear in mind there is no such thing as a 'standard' TVR.
Matt
buzzsaw said:
I've been interested by the commonly known 'fact' that the TVR V8s push out a lost less BHP than stated by TVR. The 4.6 engine used in the Range Rover, which is quoted as delivering 225 BHP. TVR gain 15->25 BHP, why only a small gain?
How about the less commonly known fact that you can't rely on other manufacturers figures either. Rover Vitesse 3528 quoted at 190, commonly 155... There are other reasons for the discrepancies: engines are built to exact tolerences (blueprinted) for testing, run without ancilliaies, etc. As Matt referred to it's the performance figures that matter and these are usually confirmed.
19560 said:
I've been interested by the commonly known 'fact' that the TVR V8s push out a lost less BHP than stated by TVR. The 4.6 engine used in the Range Rover, which is quoted as delivering 225 BHP. TVR gain 15->25 BHP, why only a small gain?
How about the less commonly known fact that you can't rely on other manufacturers figures either. Rover Vitesse 3528 quoted at 190, commonly 155... There are other reasons for the discrepancies: engines are built to exact tolerences (blueprinted) for testing, run without ancilliaies, etc. As Matt referred to it's the performance figures that matter and these are usually confirmed.
I'm certainly not complaining about the performance..thats
Looking to understand more of the technical reasons behind the discrepencies.Even better, how about manufacturers under quoting their diesel engine figures, as otherwise the sales of their 'sporty' petrol models would plummet when people realised you can have economy and performance (Friend recently had his diesel chipped, but before chipping it was already well over the declared bhp on the rolling road, and modder said this was often the case).
as i understand it, it was to keep the TVRs in line with the Porkers of the Thatcher era.
hence the Griff were quoted as similar figs (320/340bhp) to compete.
probably achieved on dyno as described earlier.
prepared engines on test beds with no ancills.
possibly did hit 340 on one before it blew!
bench figures are hardly ever acheived on the road!
as for performance figures...
like to see anyone get a std 500 RV8 to 60 in 4.2!!
but they're quick enough...I like mine anyway!
hence the Griff were quoted as similar figs (320/340bhp) to compete.
probably achieved on dyno as described earlier.
prepared engines on test beds with no ancills.
possibly did hit 340 on one before it blew!
bench figures are hardly ever acheived on the road!
as for performance figures...
like to see anyone get a std 500 RV8 to 60 in 4.2!!
but they're quick enough...I like mine anyway!
The problem for TVR was that they had the likes of John Eales and Andy Rouse building engines for the mid 80's 390's etc producing close to if not the claimed 275 bhp, later TVR hads to produce these units in greater volume hence lower spec/ output, but the figures quoted stayed more or less the same, once you claim 268/275 bhp for a 3.9 it may haved caused concern if the 5.0l etc where quoted as less than 300.
To be far though the 450 Chimaera is quite close within 10% , the AJP 4.2 is reasonably accurate, the 4.5 is spec'd to produce the quoted figures, but left the factory a little down on power, as we have vfound with a few tweeks they can hit 400 bhp.
The speed 6 is also producing as claimed, some slightly more !!
Tim
To be far though the 450 Chimaera is quite close within 10% , the AJP 4.2 is reasonably accurate, the 4.5 is spec'd to produce the quoted figures, but left the factory a little down on power, as we have vfound with a few tweeks they can hit 400 bhp.
The speed 6 is also producing as claimed, some slightly more !!
Tim
Good God after all the stick I took I notice ACT now totally agrees with me its quite possible to produce 350+ bhp from a 500 engine I have spent a fair amount of money doing this,that aside lets see what yo can do to an engineto produce more umph
Cam shaft is proberly the biggest difference
Heads port and polish with larger valves and double springs
Exhaust de-cat the bloddy thing
Larger throttle body
Get the air into the engine , this can be expensive if you go down the ACT route but it does help maybe 10-15 bhp
Silicon induction hoses
new air filter
new air flow meter (Jag)
Larger HT leads
new coil (good quality one)
get a new mapp done for your ECU not that expensive
Solid lifters if you intend to high rev the engine a lot
throw in a double timing chain while you are in there
I fitted a new set of Bosch fuel injectors (expensive ) for only a small increase in output
Doing that little lot will cost you a small fortune , YOU will get around 360 -375 bhp but as I have always said don't bother its not worth it the cars are fast enough
Simon
Cam shaft is proberly the biggest difference
Heads port and polish with larger valves and double springs
Exhaust de-cat the bloddy thing
Larger throttle body
Get the air into the engine , this can be expensive if you go down the ACT route but it does help maybe 10-15 bhp
Silicon induction hoses
new air filter
new air flow meter (Jag)
Larger HT leads
new coil (good quality one)
get a new mapp done for your ECU not that expensive
Solid lifters if you intend to high rev the engine a lot
throw in a double timing chain while you are in there
I fitted a new set of Bosch fuel injectors (expensive ) for only a small increase in output
Doing that little lot will cost you a small fortune , YOU will get around 360 -375 bhp but as I have always said don't bother its not worth it the cars are fast enough
Simon
erm I don't think Tim is agreeing with you at all .. not surprising as tim talks sense and you traditionally talk utter garbage.
what tim's saying is that even the Rouse cars made less than TVR claimed, so when the 5 litre cars came out a *realignment* of the figures was required to make owners think they were getting a more developed / more powerful car.
what tim's saying is that even the Rouse cars made less than TVR claimed, so when the 5 litre cars came out a *realignment* of the figures was required to make owners think they were getting a more developed / more powerful car.
joospeed said:
erm I don't think Tim is agreeing with you at all .. not surprising as tim talks sense and you traditionally talk utter garbage.
Easy tiger!
joospeed said:
what tim's saying is that even the Rouse cars made less than TVR claimed, so when the 5 litre cars came out a *realignment* of the figures was required to make owners think they were getting a more developed / more powerful car.
It has alot to do with the dino on which the engines were tested. And the fact that TVR tested a blueprinted engine, that was brandnew and built with the test in-mind. How anyone can expect an engine that has been mass produced and then done thousands of miles to attain the quoted BHP figuers is beyond me! Remember that these engines were mass produced by Rover then "tweaked" by TVR Power.
BHP figuers should be taken in the same vain as MPG and 0-60 times, probably produced once and the car was destroyed in the process.
All manufacturers do it. I remember reading in the press how Volvo got a great 0-60 time out of one of there cars, the engine and gearbox had to be replaced along with a cluch and two drive shafts. In other words the car had been totaled, but that was the time quoted in all the sales blurb!
Frankly, when we look at the issue in purely technical terms, it depends on whether you measure your willy in bhp or in inches 
Who cares? I've got a Griff. People smile. I smile.
I have a sneaking suspicion that my Griff doesn't do the 340bhp quoted in the handbook - like I give a monkeys
Who cares? I've got a Griff. People smile. I smile.
I have a sneaking suspicion that my Griff doesn't do the 340bhp quoted in the handbook - like I give a monkeys
2 Smokin Barrels said:
2 Smokin Barrels said:
I always measure my willy in BHP.
Maxed out at 5800 rpm
>> Edited by 2 Smokin Barrels on Sunday 17th April 21:19
Mine doesn't like cold starts!!
..but jump starts are OK eh?
Depends on how long it's been left!!
(OMG, have I suddenly turned into the Carry On appreciation club!!
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