Hemi HP

[jerseyguy123]

I was watching Mecum Auction and they bought out a Hemi Challenger. They said it had 425 horsepower. How much Really?

 

[sloinker]

If you go to Youtube there is this Canadian guy that is always dyno'ing motors including stock used hemi's from back in the day. Somewhere North of 450 horsepower in well used condition.

 

[oldhp]

Nick's Garage. He's been building HEMI's forever. Very nice guy!!!! He has "THE" dream job working on old muscle cars.

 

[jhs914]

Back in the day it was said that with just a set of open Hooker headers the 426 Hemi was good for around 500 HP. I had a buddy in high school back in 1966 who had a Plymouth Satellite with a 426 Hemi. I had a 1966 GTO with tri-power (3 two barrel carbs) and I could hang with him up to about 70 mph but after that he ran away from me. I rode with him once in a race and that thing was a monster. Scary fast.

 

[sloinker]

Back in the day it was said that with just a set of open Hooker headers the 426 Hemi was good for around 500 HP. I had a buddy in high school back in 1966 who had a Plymouth Satellite with a 426 Hemi. I had a 1966 GTO with tri-power (3 two barrel carbs) and I could hang with him up to about 70 mph but after that he ran away from me. I rode with him once in a race and that thing was a monster. Scary fast.

I think that the Canadian dyno guy's build baseline is 500HP with intake/carb/exhaust tweaks for stock compression Hemi's.

 

[Rhymingmechanic]

Quoted from a Hemmings article about a 1966 street Hemi built to stock specs. Stock HP was rated at 5000, but they ran it to 6500 RPM.

Dyno Run--without headers​

The Land and Sea dyno reveals the Hemi's actual output: 494.4 hp at 5,950 rpm and 498.3 lb-ft at 4,500 rpm. At 5,000 rpm, where Chrysler claimed 425 hp, it makes 459.3 hp.​

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Dyno Run--with headers​

Not surprisingly, the headers bumped output to 521 hp at 5,950 rpm and 502 lb-ft at 3,300 rpm, increases of 26.6 hp and 3.7 lb-ft. This prompted Donnie to say, "With a stock cam and induction, the factory manifolds are excellent. But with a hotter cam, more compression, cross-ram or stroker crank, the headers would add a lot more."​

​

https://www.hemmings.com/stories/article/how-hot-the-hemi

I've watched a bunch of Nick's teardown and dyno videos, but there's also a good one of his brother racing a Hemi Challenger. It sounds like a beast--at the end of the quarter, it starts revving like it wants to run a 1/3 mile instead.

 

[IcarusLSC]

New one, old one? Is it a 5.7, 6.2, 6.4 etc?