440 stock specs

[lordofrc]

In 1967 they advertise there 440 at 375 horspower. Is that an accurate number?

 

[MarPar]

In 1967 they advertise there 440 at 375 horspower. Is that an accurate number?

IMHO they waaaaay under rated HP back then....i think a stock 440 is closer to 400 hp.

also, no way in God's green earth a street hemi was 425hp.. i think those were closer to 500hp.

insurance reasons probably...

 

[Bens69PlymouthSatellite]

U are right Mario the older 440's were closer if not a little over or under 400 hp and the hemi was closer to 500 hp also think the 440+6 was closer to 450 hp.

 

[Cranky]

I think y'all are being a bit over optimistic. You can do some calculations on ET vs 1/4 mile speed and weight and get a good idea what these cars had. For example, I had a 440 RT Challenger that only a 14.20 with street tires. It was 3800 with me in it. Now I'm sure that I probably left some on the table by spinning some off the line and the motor was getting old but it still ran pretty good. The HP figure isn't close to being 400. Another car that was in good shape and hooked was a 68 Road Runner that ran a 10.68 @ 126 and the calculator says 540 and change and that's pretty close to what the dyno said. It was a healthy for the day, 440 but it wasn't nearly stock.

 

[74sundance]

I have a Sticky here, it posts the same info RE: 375 HP
http://www.forbbodiesonly.com/moparforum/showthread.php?t=8713

 

[Cranky]

I don't put a lot of stock into the factory numbers. My 71 340 Cuda was a good 2/10ths faster than my 440 Challenger....and it was only about 200 lbs lighter and rated only at 275 hp. The only thing different between the two, besides BB vs SB was the 340 had headers.

 

[696pack]

The factory h.p. rating are accurate as rated at the flywheel but if you look at the rpms that they were rated at it is easy to see that there was more there at higher rpms. Also distributor, carb tweeking and headers unleashed more h.p.

 

[Cranky]

The factory h.p. rating are accurate as rated at the flywheel but if you look at the rpms that they were rated at it is easy to see that there was more there at higher rpms. Also distributor, carb tweeking and headers unleashed more h.p.

Of course rpm has something to do with it as does the tune up...but I just didn't take my cars to the track with the factory tune up. I tweaked on them but both my Challenger and Cuda were points as they came from the factory and both were as they came from the factory except for the headers on the Cuda but I still don't buy the factory numbers. Some cars were screamers and some were...well, dogs.

 

[Satellite65]

A lot of those #s were for homologation purposes. In the sixties, NASCAR mandated that no engine/car combo shall be rated at more than 425 hp. Think it's a coincidence that the Hemi, 427 Chevy, 427 Ford (side oiler and SOHC) were all rated at 425 hp? Manufacturers said " yeah, OK. It's 425 hp, whatever!!" Chevrolet (GM) broke the pattern when the LS7 454 came out rated at 450 hp, right after they dropped out of factory backed racing efforts.

 

[yellowdartdave]

You gotta look at the RPM where the Hemi was rated at......


425 HP @ 5000rpm was about right...for 5000rpm

What was it making at, say 6500 ???

Sorta like my 72 Kaw 500 3cyl 2-stroke.

It made 30 hp@ 5500 and 60hp @7000. No wonder it had a wheelie problem.

The power came on like flipping a light switch.

 

[696pack]

A lot of those #s were for homologation purposes. In the sixties, NASCAR mandated that no engine/car combo shall be rated at more than 425 hp. Think it's a coincidence that the Hemi, 427 Chevy, 427 Ford (side oiler and SOHC) were all rated at 425 hp? Manufacturers said " yeah, OK. It's 425 hp, whatever!!" Chevrolet (GM) broke the pattern when the LS7 454 came out rated at 450 hp, right after they dropped out of factory backed racing efforts.

Chevy backed off of factory sponsored racing in 1957 so the rating of the 454/450 had nothing to do with that.

I am going to say this one more time, the factory rates are correct. The rating are at the FLYWHEEL not the rear wheels and were rate at where they wanted them to be and that was done so by using the rpm that fit the rating NOT necessarily the maximum h.p. at a higher rpm.

Some where I have an old Mopar book that has a period picture of factory techs doing dyno testing on the 426 Hemi and they stated that the 425 h.p. rating was right on for the rpm they were rating it at. I thought I had scanned this book page but can't seem to find it now but believe me those are the facts. Remember, the Hemi LOVES high rpms but the real h.p. is bottled up with the factory exhaust manifolds and cam that really allows the great heads to breathe.

The factory h.p. rating of 425 @ 5000 rpms is correct but do the math on this engine built to NHRA stock class specifications at 6000 rpms and you will get a B body at class weight that will run high 10s. Understand that is with a stock lift cam that allows a different grind for lob seperation and duration and higher compression due to blueprinting and headers with stock carbs. Allowing for limitless cam, compression, and different induction methods and fuels and the h.p. goes into the 1000s the Hemis success (no secret) are the great breathing heads.

The bottom line is that the h.p. was low on these cars (not just Hemis but other Mopars and the competition) limited initially by the rpms they were rated at because the stock cam, heads, exhaust manifolds, and carbs WERE capable of more h.p. at higher rpms.

 

[Satellite65]

Chevy backed off of factory sponsored racing in 1957 so the rating of the 454/450 had nothing to do with that.

I am going to say this one more time, the factory rates are correct. The rating are at the FLYWHEEL not the rear wheels and were rate at where they wanted them to be and that was done so by using the rpm that fit the rating NOT necessarily the maximum h.p. at a higher rpm.

Some where I have an old Mopar book that has a period picture of factory techs doing dyno testing on the 426 Hemi and they stated that the 425 h.p. rating was right on for the rpm they were rating it at. I thought I had scanned this book page but can't seem to find it now but believe me those are the facts. Remember, the Hemi LOVES high rpms but the real h.p. is bottled up with the factory exhaust manifolds and cam that really allows the great heads to breathe.


The factory h.p. rating of 425 @ 5000 rpms is correct but do the math on this engine built to NHRA stock class specifications at 6000 rpms and you will get a B body at class weight that will run high 10s. Understand that is with a stock lift cam that allows a different grind for lob seperation and duration and higher compression due to blueprinting and headers with stock carbs. Allowing for limitless cam, compression, and different induction methods and fuels and the h.p. goes into the 1000s the Hemis success (no secret) are the great breathing heads.

The bottom line is that the h.p. was low on these cars (not just Hemis but other Mopars and the competition) limited initially by the rpms they were rated at because the stock cam, heads, exhaust manifolds, and carbs WERE capable of more h.p. at higher rpms.

OK. So why would they intentionally rate these engines at lower outputs than what they were actually capable of producing knowing all well that horsepower claims help sell cars? Everyone wants to have "the big stick".

 

[696pack]

OK. So why would they intentionally rate these engines at lower outputs than what they were actually capable of producing knowing all well that horsepower claims help sell cars? Everyone wants to have "the big stick".

Because insurance companies LOOKED at h.p. rating in determining THEIR rates. Insurance rating is one of the things that KILLED muscle cars. Staring in 1970 the insurance cost per month often was the same as the monthly car payment and buyers could not AFFORD all of this. From experience I was selling these cars NEW from 68-74.

 

[Meep-Meep]

It's my understanding that how power was measured changed at some point. For example the 340 was rated at 275 HP, but at the back of the tranny with all accessories installed and operating. Would this be true? I bet that engine is closer to 1 HP per inch at the flywheel. I understand what you are saying about limiting the RPM, since HP is a function of RPM. It's like politics where one has to speak in half truths so they can't get accused of outright lying to the insurance companies.

 

[MarPar]

IMHO they waaaaay under rated HP back then....i think a stock 440 is closer to 400 hp.

also, no way in God's green earth a street hemi was 425hp.. i think those were closer to 500hp.

insurance reasons probably...

figures...:evil5:

 

[Meep-Meep]

You gotta look at the RPM where the Hemi was rated at......


425 HP @ 5000rpm was about right...for 5000rpm

What was it making at, say 6500 ???

Sorta like my 72 Kaw 500 3cyl 2-stroke.

It made 30 hp@ 5500 and 60hp @7000. No wonder it had a wheelie problem.

The power came on like flipping a light switch.

I rode a tricked out Kawi 750 triple once. I knew better than to give it full throttle, and even then it wanted to go out from under me. Yup, 4000 RPM and that thing was ON!! Unreal acceleration.

 

[Dennis H]

Doesn't matter now. Build the best streetable pump gas 440 you can and enjoy.

 

[69hemibeep]

This was discussed on another forum some time back, and some one posted a pic of a 60's factory dyno sheet of a street hemi and it peaked a 466 HP, but I don't remember at what rpm.

 

[Cranky]

The Hemi engine was hand built, correct? And I'm sure they took more time to make sure it was right but regular production engines were all over the board with the horsepower number and tolerances but if you want to believe the hp numbers were correct and on the money, that's fine with me. There was also no core shift in any of the castings what so ever and all bodies had no fitment issues either.....

 

[68pplcharger]

It's my understanding that how power was measured changed at some point. For example the 340 was rated at 275 HP, but at the back of the tranny with all accessories installed and operating. Would this be true? I bet that engine is closer to 1 HP per inch at the flywheel. I understand what you are saying about limiting the RPM, since HP is a function of RPM. It's like politics where one has to speak in half truths so they can't get accused of outright lying to the insurance companies.

The power measurement did change. Pre 72 the motors were tested for gross horsepower. i.e. no accessories attached. Now they are tested for net horsepower i.e. all accessories attached. They are both still tested at the flywheel. I can't believe i found a link that listed the details, cool


http://neptune.spacebears.com/opine/horsepwr.html