Rolling Road day.

[F Body]

As most of you are aware I'm taking the Maro on Edges Rolling road day next weekend

Been looking through all the 4th Gen documentation that I have :

Chevrolet Z28 European Specification ( printed in Luton ) :

288 BHP @ 5,200rpm and 437n/m of torque @ 4,000rpm.

Build sheet & specification from GM Canada just states 305 HP.

Two questions really , is Euro BHP the same as American HP and will the stated figures be at the flywheel or rear wheels ?

If they are @ the flywheel what sort of losses would you expect through the drive train ? ( oop's sorry that's 3 questions ! )

The SLP loudmouth exhaust system can add up to 25 extra BHP , so I 'm hoping to just break the 300bhp barrier ?

[55starchief]

rear wheel hp is normaly lower than fly wheel. Dont believe everything people tell you about magic 25hp pickups you might se 5 or 10 at the most on a normally asperated motor, turbo motors used to benefit from a larger exhaust as they would pick up a small amount of boost

Most rolling roads will calculate the fly wheel power mate

[F Body]

How can they calculate the flywheel figure if they don't know what the transmission is ?
I thought the rollers would be calibrated and give an accurate at the wheel figure ??
All a bit too technical for me

[55starchief]

Quoting: F Body

How can they calculate the flywheel figure if they don't know what the transmission is ?
I thought the rollers would be calibrated and give an accurate at the wheel figure ??

It calculates it back from the real wheel figure frim memory. I think its about a 20% loss through the trans

[F Body]

Quoting: 55starchief

I think its about a 20% loss through the trans

Holy Smowly that's nearly 60 bhp
or one Fiat Panda

[philoldsmobile]

the flywheel figure is often from a dyno with no trans attached (rather than a rolling road or chassis dyno as they are sometimes known)

305 flywheel sounds about right for 285 rwhp

incidently, in the muscle cars of the 60's (especialy dodge) they measured the power at the flwheel, with nio ancilleries - no water pump, no alt nothing..

hardly a fair representation.

when they changed the ratings in the early 70's power dropped to half of the previous years, but the 1/4 mile times didn't really change much..

the 72 460 mustang made about 360bhp, the 73 made about 280, but both ran low 16 second 1/4 mile times.

[55starchief]

Quoting: F Body

Holy Smowly that's nearly 60 bhp
or one Fiat Panda

The difference between flywheel horsepower and rear-wheel horsepower will vary from vehicle to vehicle, depending on many factors," adds Gale Banks Engineering, "but we find that rear-wheel horsepower is usually between 18 percent and 25 percent less than flywheel horsepower."

 


Damn im good, mind of complete crap me

[philoldsmobile]

its a lot less for modern cars though..

oddly, there isn't much diffeence between auto and manual either..

[55starchief]

Quoting: philoldsmobile

its a lot less for modern cars though..

Its still about the same mate, my boss had his group B subaru motor engine dynoed and chassis dynoed and it was 20% different, thats how i knew the losses

[philoldsmobile]

cant compaire two different dyno's mate, the same car on two different dynos both meausring at the wheels can measure 10% different...

they aint that precise a tool..

old auto's were far less efficient than the modern ones, its called progress..