Hooker Super Comp 1-3/4 Headers - Max Horsepower?

[Falcon67]

>What I don't want is an engine that makes 650 on the dyno and 600 in the car.

Good luck - dyno to car means mucho compromises.

https://www.dragzine.com/tech-stories/dyno-days-an-inside-look-at-what-all-the-dyno-numbers-mean/

"We’ve performed back-to-back tests and witnessed a naturally aspirated, 400-horsepower street engine gain ten horsepower just by reducing the starting coolant temperature from 180 degrees to 135 degrees. That’s free horsepower.

Another trick that can go unnoticed is the configuration of the headers used in testing. For example, Westech Performance prefers to use its own dyno room headers, not only because they allow easy access to spark plugs, but also because the primary tubes extend almost horizontally from the engine. This straight shot from the exhaust port tends to improve peak horsepower with no cost to low-end power. It’s a small thing but it all adds up.

Most dyno cells also use an electric water pump to circulate water with the engine off to quickly stabilize the engine coolant temperature. But this pump also eliminates the parasitic loss of driving a water pump with the crankshaft. On a 6.0L LS engine, we’ve seen six- to eight-horsepower improvements after replacing an entire LS truck accessory drive (water pump, alternator, and power steering pump) with an electric water pump.

Street engines require an air filter, yet very few dyno sessions are performed with an air cleaner in place. However, we discovered (by accident) an eight-horsepower loss on a 550-horsepower EFI small-block when a one-inch spacer was used underneath an air cleaner base to provide clearance for throttle linkage on a four-barrel throttle body.

The spacer was necessary for the throttle linkage to clear the filter base. By adding a gentle radius to the base, we eliminated the spacer and the power came right back. Had we not tested the engine exactly the way it was going to be run in the car, we would not have discovered that power loss."

[1968galaxie]

^^^ Good post!

[jayb]

What I don't want is an engine that makes 650 on the dyno and 600 in the car.

An engine will almost always show HP and torque numbers on the dyno that are higher than the ones it achieves in the car.  This is because the dyno numbers are corrected to a standard set of weather conditions.  Standard dyno correction is to assume sea level atmospheric pressure (29.92" barometer) and 60 degrees Fahrenheit inlet temperature.  This is done so that comparisons between engines, or parts on a particular engine, are standardized.  If you are any higher than sea level, or any higher in inlet temperature, the actual torque and HP numbers will go down.

On the other hand, if you are running at sea level, and with a high pressure system overhead, and the temperature is cooler than 60F, you will be making more power than what is shown on the dyno.

The dyno will show you the raw, uncorrected data as well as the corrected data, and the raw data is the power that the engine is making with the weather conditions at the dyno.

There's a bunch of information in my book about how weather conditions affect an engine's performance.  It gives you the formulas to calculate correction factors so you will know how much power you are losing if you are running at, say, 1200 feet of altitude and 75 degrees F, on a low pressure day, compared to standard dyno conditions.  On my dyno, at an altitude of 940 feet, I will typically see summertime correction factors in the 3% to 7% range.

Bottom line is that standard dyno numbers (assuming they are accurate) are very useful for comparisons between engines, but you aren't likely to see numbers that high during normal operation.

[Heo]

Here you notice that on late summer nights, cold with slight night fog (about 10 feet above sea level)
you pick up a good amount of power. Especial noticeable on low power
engines like a Model-T or A, where you also can adjust fuelratio with the
twist of the choke nob  They get a topspeed that scares you,,,not that
it takes that much to do that

[jgkurz]

Falcon67 and Jayb,  Thank you for the thoughtful responses. I feel I should qualify my statement. I do know that HP on an engine dyno is difficult (maybe impossible) to duplicate in the car. I simply what to maximize the HP in the car within reason. For example, I don't want to chop up my car to fit race headers or mod the hood for a state of the art fresh air scoop. My car does street and strip duty so compromise is required.

Jay, while we are on the subject of FE Mustang headers, what headers did you use on your 69 Mach1 2005 DragWeek winner with the 511ci? Also, do you have any comments on the Hooker Supercomp 1-3/4 headers on 600+ HP FE's? I'd be grateful for your input.

-John

[fryedaddy]

Jay,s book has a lot of info on all the headers and exhaust.

[jgkurz]

Jay,s book has a lot of info on all the headers and exhaust.

I've read it front to back and back to front. : )

[Falcon67]

>I don't want to chop up my car to fit race headers or mod the hood for a state of the art fresh air scoop.

No problem, that's expected.  Your plan should include a good dyno session and then at the strip, be prepared to mess with the WOT jetting to see if there is MPH available.  As an example, I got decent AFR readings from the 302 with a t-ram and dual Edelbrock 600s.  No problem driving it around, graph looked real close with out-of-the-box jetting.  At the track after a number of test runs, +4% (one step in the Ed tuning book) rich primary and secondary on both carbs made best MPH. 

My dragster makes easy 575HP using what look like small tubes on the headers at 1 3/4".  Small compared to the 2 1/4 most of the BBC dragsters use.  But - no shock towers on the rail LOL.  The door car has a 351C-4V and the pipes on that are 1 7/8", and make the required quickie bends right out of the head. 

[Joe-JDC]

My "little" 375 Y Block made 563/595 with 1 5/8" stepped to 1 3/4" into 3 1/2" collector.  Same basic set-up made 603.2 hp at EMC in another engine.   So 600 hp should be doable with a 1 3/4" primary for an FE.  Joe-JDC