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Old 10-13-2021, 11:59 AM
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Default Which one would you choose?

Just curious which dyno curve would you choose for your street car (red or blue curve)
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Old 10-13-2021, 12:03 PM
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Blue...torque is king for a street car. An engine produces torque. HP is an equation......... HP = (torque x RPM)/5252

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Old 10-13-2021, 01:48 PM
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Depends on gearing and if you prefer to spin it!

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Old 10-13-2021, 02:07 PM
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That is one spunky OHC!

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Old 10-13-2021, 02:16 PM
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What are those vertical numbers on the left of that chart!?

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Old 10-13-2021, 03:00 PM
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Quote:
Originally Posted by steve25 View Post
What are those vertical numbers on the left of that chart!?
HP numbers but cut off some

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Old 10-13-2021, 05:36 PM
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Looks like a overlay of a 455 and a 454 but can’t see your hp scale.

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Old 10-13-2021, 08:04 PM
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Looks like substantial torque loss (Red) for limited HP gain. I'd expect more power gain with that RPM carry.

Blue would be better for 'most' street cars. A radical Red guy could run a good 5000 stall. lol but I'd want power to carry well past 6500 RPM.

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Old 10-13-2021, 08:18 PM
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Depends how old your are,now at close to 76 my engines with OD trans virtually dont see 3500 anymore.Off idle to 2000 now where I live on the street.Tom

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Old 10-13-2021, 08:28 PM
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Quote:
Originally Posted by tom s View Post
my engines with OD trans virtually dont see 3500 anymore.Off idle to 2000 now where I live on the street.Tom
I'd be thinking EFI - V6
Heck even Turbo the beast for some 'passing power'

If I don't demand more, I'll settle for much less.

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Old 10-13-2021, 08:38 PM
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Depends on converter and gear

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Old 10-13-2021, 09:00 PM
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don’t you kind of want the full y axis numbers to answer this question? i know i would rather have 35 hp than 20 hp at 4500 rpm regardless of what happens at 5800-6000 rpm. but i might choose to accept, say, 520 hp at 4500 instead of 535 if it meant i got 620 at 6000 instead of 610 at 5800.

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Old 10-13-2021, 09:26 PM
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Blue...

I just built a basic 400 similar to a W72. spc-4(066) cam installed at 113. 8.2:1 compression 6x-4 heads with stock intake. Dougs headers and 2.5 dual exhaust. the car is my 79 TA with a 2.64 first gear Super T10 and 3.42 gear. I was not expecting much, but I was quite suprised. having torque everywhere is quite fun.

my current motto is don't over cam for the street.

Grain of Salt here, but added what DD2000 says about the build
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Old 10-13-2021, 09:45 PM
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Dyno of 3 cams and 2 intakes. 60 HP swing from bottom to top. 10 CR 454 with AFR 265 heads.

With a 4500 stall converter I'd want the Black curve it used a solid roller 248/256 @ .050 - .630 valve lift - 110 LSA.

Red and Black used a single plane intake, others were dual plane.
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Old 10-14-2021, 12:01 AM
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Quote:
Originally Posted by george kujanski View Post
An engine produces torque. HP is an equation......... HP = (torque x RPM)/5252
Except cylinder pressure comes before torque.
Here's a power equation for smarter people that does not use torque at all.
https://www.grc.nasa.gov/www/k-12/airplane/ottoa.html

There was a long debate on Speed-talk. I was not surprised the best of the best agreed horsepower was king. They probably had 100 NHRA records between them. Legit.

Nascar R&D measures HORSEPOWER for every cylinder in their engine from cylinder pressure.
https://www.youtube.com/watch?v=rBZCnG1HwDM


Last edited by pastry_chef; 10-14-2021 at 12:10 AM.
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Old 10-14-2021, 12:05 AM
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Quote:
Originally Posted by george kujanski View Post
Blue...torque is king for a street car. An engine produces torque. HP is an equation......... HP = (torque x RPM)/5252

George
an engine produces rpm, too. and the more rpms it produces a given amount of torque at, the faster the engine does work. and moving a car is work.

there is no getting around the fact that power equals work over time. if you reduce power, it takes longer to do the same amount of work.

do you think you would you go faster with an engine that peaks at 1000 ft lbs of torque at 1000 rpm, or one that peaks at 500 ft lbs of torque at 6000 rpm? the first has a higher torque figure, but the second makes three times more power and will accelerate any pontiac in existence much more quickly.

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Old 10-14-2021, 12:19 AM
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Torque is putting your beaker bar on the wheel nut and then adding force, WITHOUT MOVING THE NUT.

When / IF I move the nut, then force was applied over angular distance and there was a start time and a stop time.
Force exerted through radians over time = POWER always. I did work and power does work. Torque cannot do work.

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Old 10-14-2021, 12:21 AM
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Guys this is the street section not the race section. Racing rpm and hp are king but for a street car (one that actually gets driven a lot with good drive ability) not sure rpm/hp is king. Say you have 4000lb car with 3.42 gears and 3000-3500 stall, which one you taking?

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Old 10-14-2021, 12:25 AM
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Quote:
Originally Posted by slowbird View Post
Say you have 4000lb car with 3.42 gears and 3000-3500 stall, which one you taking?
I'll choose an engine that makes BIG POWER from 3000 RPM to 5000 RPM.
Still power.

Power is made from 3 things.
1 Displacement
2 RPM / piston speed.
3 efficiency - BMEP.

Efficiency is very limited. Fuel says compression can only be so high.
When RPM is limited that leaves BIG displacement / engine size to increase power there.

Using mean piston speed.
horsepower = (BMEP * engine total bore area * MPS) / 132000

Woks at only 1500 RPM or 10000 RPM. Let pick a well designed 600 cube engine for your example, will be hard to beat.


Last edited by pastry_chef; 10-14-2021 at 12:37 AM.
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Old 10-14-2021, 12:26 AM
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Quote:
Originally Posted by slowbird View Post
Guys this is the street section not the race section. Racing rpm and hp are king but for a street car (one that actually gets driven a lot with good drive ability) not sure rpm/hp is king. Say you have 4000lb car with 3.42 gears and 3000-3500 stall, which one you taking?
maybe the blue one, since it probably makes more average power over the range of rpms that it will see in street use ...

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