Accepted exageration- the' Blackpool bhp' factor?

[iguana]

Just curious, as it seems well known that TVR quote a power figure & then rolling road operators struggle to ever get near it with standard cars, is there an accepted %age factor or common bhp amount for the'Blackpool exageration factor'?

Also is it with all TVR engines or are some worse than others, for example are the AJP units bang on the quoted power, but speed six & Rover V8 based way off etc etc ??

[Pies]

My 4L is claimed 240 bhp and 270 lbft

on the rollers today it made 238 bhp and 263lbft

no probs here

note these are corrected figs as the engine would probably been tested on a dyno at TVR

[j_s_g]

iguana said:

Also is it with all TVR engines or are some worse than others, for example are the AJP units bang on the quoted power, but speed six & Rover V8 based way off etc etc ??

Quoted Speed 6 engine outputs are reasonably accurate. AJP ones are well off, especially on the 4.5. I'm no expert on RV8s in TVRs, but I wouldn't expect them to be too far wrong.

[pddmac]

that ings true with what i have heard, some six'es actually achieve greater than quoted outputs, AJP's are known to be well off, still it's a pity though

[mlumb]

4.5s are well off,4.2s are usually pretty close,mine made 345bhp.

mike

[Plotloss]

The Rover engined cars and the AJP8 are generally speaking a little optimistic in their outputs. I believe DannyLT's Cerb RR is about the most a stock Cerb has made and that was quite an amount under book.

The Speed Sixes however are usually bang on the money.

[jellison]

if a 4.0 rover made 238 even at the fly wheel their rollers are Massively exaggerating - Lucky to make 210 in reality

[joospeed]

Danny's car made 350 before RR upgrade, 398 after.

Most powerful cerbie I've tested was 361bhp (standard) and 425 bhp (red rose).

There is 440 bhp to come from a RR engine if only blackpool would map an engine correctly for once ...

Most powerful 4 litre rover engine I've tested made 216bhp.

[griffman]

have had my 4.0 griff for nearly 3 years now, when first got it put on rollers and only had 208bhp. have now spent a few pennies at v8d and mark adams to get up to a respectable 258bhp.

[Incorrigible]

jellison said:

if a 4.0 rover made 238 even at the fly wheel their rollers are Massively exaggerating - Lucky to make 210 in reality

Are you sure, the standard Range Rover one makes 180-190

[AJLintern]

Why is the specific output comparatively low for the RV8? Are they built more for torque than power? Even the 3.0 straight 4 in my 944 produces 211bhp/207lbft. So putting a RV8 in a 944 wouldn't make it that much quicker then...

[nubbin]

joospeed said:

Danny's car made 350 before RR upgrade, 398 after. Most powerful cerbie I've tested was 361bhp (standard) and 425 bhp (red rose). There is 440 bhp to come from a RR engine if only blackpool would map an engine correctly for once ... Most powerful 4 litre rover engine I've tested made 216bhp.

What's the best you've seen from a 3.6 speed 6, Jools?

[GingerNinja]

Do TVR say at what position of the vehicle they're measuring the bhp at?

....it's just that the majority of motocycle manufactures quote a power figure at the crank, which is obviously far greater than when measured at the backwheel.

[Nick P]

I was told it is because TVR measure the bhp in 'snap bhp', i think this is where they crack the throttle open and measure the highest spike of power.....???? hence getting a higher reading.

[Resh]

GingerNinja said:

Do TVR say at what position of the vehicle they're measuring the bhp at? ....it's just that the majority of motocycle manufactures quote a power figure at the crank, which is obviously far greater than when measured at the backwheel.

Just about all manufacturers measure at the flywheel, including TVR. Transmission loss is about 30% (I think), meaning considerably less power at the wheels.

[joospeed]

nubbin said:

joospeed said: Danny's car made 350 before RR upgrade, 398 after. Most powerful cerbie I've tested was 361bhp (standard) and 425 bhp (red rose). There is 440 bhp to come from a RR engine if only blackpool would map an engine correctly for once ... Most powerful 4 litre rover engine I've tested made 216bhp. What's the best you've seen from a 3.6 speed 6, Jools?

No .. not tested a 3.6 yet, but the only 4 litre SP6 I've tested made more than TVR claim .. 373bhp from a supposedly std Tuscan rated at 360bhp.

[Plotloss]

Resh said:

GingerNinja said: Do TVR say at what position of the vehicle they're measuring the bhp at? ....it's just that the majority of motocycle manufactures quote a power figure at the crank, which is obviously far greater than when measured at the backwheel. Just about all manufacturers measure at the flywheel, including TVR. Transmission loss is about 30% (I think), meaning considerably less power at the wheels.

Transmission loss ISNT a percentage.

It would mean that a 32bhp Mini loses 10hp where as a 1000bhp Veyron would lose 300bhp doing ostensibly the same job...

[Resh]

Plotloss said:

Resh said: GingerNinja said: Do TVR say at what position of the vehicle they're measuring the bhp at? ....it's just that the majority of motocycle manufactures quote a power figure at the crank, which is obviously far greater than when measured at the backwheel. Just about all manufacturers measure at the flywheel, including TVR. Transmission loss is about 30% (I think), meaning considerably less power at the wheels. Transmission loss ISNT a percentage. It would mean that a 32bhp Mini loses 10hp where as a 1000bhp Veyron would lose 300bhp doing ostensibly the same job...

Thanks for setting me straight - typically, what sort of loss would you be looking at?

[Marlon]

Plotloss said:

Transmission loss ISNT a percentage. It would mean that a 32bhp Mini loses 10hp where as a 1000bhp Veyron would lose 300bhp doing ostensibly the same job...

I understood it to be a combination - for rear wheel drive cars around 17% plus 10bhp (approx) - i.e. 300BHP at the flywheel would be 300 - 17% (51BHP) - 10BHP = 239 BHP at the wheels.

On the whole you might expect a more powerful engine to suffer more loss because of the increased mechanical friction and heat generated etc. So your Bugatti Veyron would almost certainly have a greater loss than a Fiat Panda, but there would also be a fixed loss due to the use of similar mechanical components and engineering principles?

>> Edited by Marlon on Friday 28th November 12:49

[HarryW]

jellison said:

if a 4.0 rover made 238 even at the fly wheel their rollers are Massively exaggerating - Lucky to make 210 in reality

No really, the figure given is about 30bhp over what this road normally gets for most 4ltrs, around 190bhp at the wheels in this case most make 160-170 at the wheels. I've used the same road amongst others and think its as accurate as it gets.
Agree most 4ltr Tivs make 200-210 corrected flywheel bhp. It just so happens Pies has got a particulary strong engine, most are not.

harry