what kind of performace figures should u get with a 455 in a 3750lbs car?

[Oldsprepp]

With a 455 450hp (not rwhp) in a 3750lbs with Dragradials. ?

0-60=?

1/8 =?
1/4 =?

if someone has a similar car with about that set up?

[Redog]

http://www.race-cars.net/calculators/et_calculator.html

Assuming 20% drivetrain loss (375 at the wheels) you're looking at 12.549 @ 108.61 miles per hour

[Rallye469]

Did you arrive at 450 hp with a dyno...or just a knowledgeable guess?

There's more to it then hp, tires & weight but I guess the above # is a good # to shoot for.

[Oldsprepp]

No just trying to deside how much hp i need to get to the numbers a want to be at....i want to land around 12secs a 1/4mile.

i dont want to waste money underbuilding or overbuilding the engine..
thx for the answers..

[Rallye469]

Gotcha...Well if you can get it down to 3750 with you in it mid 12's
shouldn't be too difficult. Some nice heads and a smart cam choice
will land you there squarely.

That calculator is generous...
Between my dyno #'s and my trap speed it shows I'm only loosing 16.8%
through the drive line.
My car is NOT that efficient.
With a TH400 & a 9" rear I thought it would be around up around 20-25% loss.

[Redog]

I've heard some places say 17% loss and others say 23% loss in the drive train. 20% is right in the middle

[88 coupe]

Originally Posted by Oldsprepp

........ a similar car with about that set up?

439 HP at 5400 RPM.

3950 lb.

Bias ply street tires.

11.9xx at 114 miles per hour

Close enough?

Norm

[Oldsprepp]

Originally Posted by 88 coupe

439 HP at 5400 RPM.

3950 lb.

Bias ply street tires.

11.9xx at 114 miles per hour

Close enough?

Norm

oh nice figures! thx for the info!

[Rallye469]

With a 455 450hp (not rwhp) in a 3750lbs with Dragradials. ?

[88 coupe]

Originally Posted by Oldsprepp

........ thx for the info!

Glad I could help. If you have any further questions, just ask.

Norm

[88 coupe]

Originally Posted by Rallye469

Read the whole post before you start more of your BS. Or did you? Did you use those childish bold fonts to divert everyones attention from the other part of the same post?

Either way, here it is again:

Originally Posted by Oldsprepp

........ if someone has a similar car with about that set up?

450 HP = 450 HP, regardless of the displacement. Do you think 439 HP is not "similar" enough?

Conventional thinking is that: 100# = About one tenth. Do you think 3950# is not "similar" enough?

Norm

[Rallye469]

I just wonder if you read the post Norman.
The whole post.

88 coupe
Quote:
Originally Posted by Oldsprepp
........ a similar car with about that set up?
439 HP at 5400 RPM.
3950 lb.
Bias ply street tires.
11.9xx at 114 miles per hour
Close enough?
Norm

I was just asking if that 439 HP was on an engine dyno or a chassis dyno.
439hp is close enough to 450hp for me...
It's a fair comparison.

But 439 hp at the crank won't put you at 11.9 in a 3950lb car
and 439 hp at the rear wheels wasn't what he was asking about.

So- I'm not starting BS, I am calling BS Norm.
Plain & simple.

[88 coupe]

Originally Posted by Rallye469

........and 439 hp at the rear wheels wasn't what he was asking about ........

Read this entire thread again.

Then quote the part where someone said the OP was not asking about flywheel HP?

Then read this post, again.

Norm

Originally Posted by 88 coupe

439 HP at 5400 RPM.

3950 lb.

Bias ply street tires.

11.9xx at 114 miles per hour ........

Note the applicable exceptions. They are:

• 439 HP as opposed to 450 HP

• 3950# as opposed to 3750#

• Bias ply tires, as opposed to drag radials

Then quote the part where I said anything about a “chassis dyno”, as opposed to a “real dynamometer”.

Norm.

[Rallye469]

Then quote the part where I said anything about a “chassis dyno”, as opposed to a “real dynamometer”.

That's the point.
You didn't.

So...
Which is it?
He was not asking about RWHP.
Says so in his first post in this thread.
I quoted it and bolded 'not RWHP' again.

So which is it Norm?

[88 coupe]

Originally Posted by Rallye469

That's the point ........

Yes, it is.

Originally Posted by Rallye469

........ You didn't ........

No, I didn't.

Originally Posted by Rallye469

........ He was not asking about RWHP ........

No, he wasn't.

Originally Posted by Rallye469

........ Says so in his first post in this thread ........

Yes, it does.

Originally Posted by Rallye469

........ I quoted it ........

Yes, you did.

Originally Posted by Rallye469

........ and bolded ........

Yes, you did.

Norm

[Rallye469]

Originally Posted by 88 coupe
Yes,

Originally Posted by 88 coupe
No,

Originally Posted by 88 coupe
No,

Originally Posted by 88 coupe
Yes,

Originally Posted by 88 coupe
Yes,

Originally Posted by 88 coupe
Yes,

That clears it all up.

[344870M]

I had a 66 Starfire for my first car. I remember reading (and not knowing what it meant) a "taxable" horsepower figure for the car. I think it was about 75. This means (I guess) that there was about 300 horsepower at the rear wheels. I raced the car in the eighth mile and ran my quickest run at 9.36 seconds. Not bad for a 4200lb car with 3.08/3.23 (?) gears and an auto. Can someone w/a Starfire confirm that number?

This calculator would then put my big ol Starfire at 14.04 in 1/4 with a trap speed of 97. It was pushing 75 in the eighth.
That sounds about right.

However... My 70 W30 4 spd w/4.33's... I would hope/think that this car has more rear wheel hp than the Starfire. They're both rated at 375. Sure. OK.

Never raced it, but using figures I've read. A 3750 lb car running the recorded time of 13.88 puts r/w hp at 257. That's about -30% loss. And makes the car a dog. It is NOT a dog. And it gets ALL OVER that big Starfire. I find it hard to believe that after all that was done to the W machines it would only run .16 seconds quicker. Or am I figuring something wrong.
The original owner told me the car ran high 12's. But then memories get fuzzy don't they.


Here's a clip of the W from a few years ago. She was loosing vacuum out the back of the intake so she wasn't running as well as she could.

http://www.youtube.com/watch?v=5y_OKnABGJ0

[88 coupe]

Originally Posted by 344870M

........ I remember reading (and not knowing what it meant) a "taxable" horsepower figure ........

Simply put, it's a different method of measuring power output. Nothing to do with this topic.

Originally Posted by 344870M

........ This calculator would then put my big ol Starfire at 14.04 in 1/4 with a trap speed of 97 ........

In order for it to work, the correct numbers must be entered, and the cars configuration must match the one the formula represents.

Because we are using different numbers, the formula has nothing to do with this topic.

Originally Posted by 344870M

........ They're both rated at 375 ........

What they were "rated" at, depended largely on marketing needs at the time, and the figure was not directly related to the actual power output of a given engine.

Originally Posted by 344870M

........ Never raced it, but using figures I've read .........

The thread owner was looking for hard numbers, not fairy tales. As you can see, he got them in post #7, and the thread was finished (in more ways than one) with #8.

Posts #2 through #6 and from #9 on, would be the cause of your confusion.

Originally Posted by 344870M

........ The original owner told me the car ran high 12's ........

That's about what they did. All it took was a pair of slicks and a competent driver.

Norm

[Rallye469]

RAC or Taxable Horsepower:

This measure was instituted by the Royal Automobile Club in Britain and was used to denote the power of early 20th century British cars. Many cars took their names from this figure (hence the Austin Seven and Riley Nine), while others had names such as "40/50 hp", which indicated the RAC figure followed by the true measured power.
Taxable horsepower does not reflect developed horsepower; rather, it is a calculated figure based on the engine's bore size, number of cylinders, and a (now archaic) presumption of engine efficiency. As new engines were designed with ever-increasing efficiency, it was no longer a useful measure, but was kept in use by UK regulations which used the rating for tax purposes.

I never knew that...just always thought it was an industry term that loosely described a line of automobiles horsepower ratings.

Despite what some think, that's pretty much what this thread is about.
(or at least it's a huge sidebar)
Deducing a 1/4 mile time from a given HP rating.

Ding! Ding! Ding!

That's the problem. Taxable, gross, brake/net/crank, rwhp/effective horspower are all measured differently.

Oldsprepp was smart enough to ask very specifically what 1/4mile #'s
could be expected from a RWHP rating...a specific type of measurement.
Others, the more obtuse, don't really care or at the very least,
don't care to specify what type of rating they have used.

[88 coupe]

Originally Posted by Rallye469

........ Oldsprepp was smart enough to ask very specifically ........

Yes, he was.

Originally Posted by Rallye469

........ very specifically what 1/4mile #'s could be expected from a RWHP rating ........

Not, what he specifically asked for.

Here it is, again:

Originally Posted by Oldsprepp

With a 455 450hp (not rwhp) in a 3750lbs with Dragradials. ? ........

He, very specifically, asked for something other than RWHP.

He did not, very specifically, ask for something other than Taxable HP. He could not have, because it has nothing to do with his thread.

Here is, specifically, what he did ask for:

Originally Posted by Oldsprepp

oh nice figures! thx for the info!

He got, very specifically, what he, very specifically, asked for.

Originally Posted by Oldsprepp

........ Others, the more obtuse ........

Not The kind of schoolyard BS, I would expect, from an adult (or an "engineer"). More like what a BS artist resorts to, when he/she gets a hand slapped.

In my experience, an engineer will carry on a logical/rational/mature discussion, even when he is wrong. Right, Joe?

Originally Posted by Oldsprepp

........ don't care to specify what type of rating they have used ........

Here it is, again:

On second thought, after three times, I'll just leave you to find it for yourself.

Originally Posted by Rallye469

That clears it all up.

Yes, it does.

Norm.

[Rallye469]

Oh Norman...

Once more:

439 HP at 5400 RPM.

3950 lb.

Bias ply street tires.

11.9xx at 114 miles per hour

Close enough?

If (and I'll ask again oh great one) that 439hp is at the crank
you did not go 11.9.

-or-

If you went 11.9, that 439hp was measured at the wheels.

No need to give a straight answer this time either...
You'll just find something else to criticize about they way
I asked or spelled or punctuated or bolded or underlined
or italicized or thought or wrote or assumed or asked
or learned or didn't learn or defined or...

BTW...What's wrong with engineers? Someone has to drive the train!
Choo! Chooooooooo!

[88 coupe]

Originally Posted by Rallye469

........ and I'll ask again oh great one ........

You are free to ask anything you wish