Where's the hidden horsepower?

[moparmarc]

I rebuilt the stock 440 for my 1967 GTX and here's where it stands:

Stock HP 440 block bored .030 over, zero decked.
Speed Pro forged pistons (six-pack pistons)
Stock rods from 440source.com
915 heads with 2.08 int./1.81 exh. valves
Fel-Pro stock head gasket
Comp cam XE275HL grind, 231 int./237 exh. duration, .525 in lift
Stock rockers, lifters and pushrods from 440source.com
Stock cast iron intake and HP exhaust manifolds.
Stock AFB carb (4326S)

I took the motor to a dyno shop and did the break-in on the dyno, then played with the carb the rest of the day to get it setup. We found that the horsepower was between 345 and 355, torque between 450 and 457. Detonation was present above 30 degrees advance, so that's where we set it (highest numbers were at 32 degrees). With a big Holley double-pumper, the numbers weren't any better.

Seeing as the stock numbers for the 67 440 is 375 HP and 480 ft-lbs of torque, why are my numbers lower? We ran the motor with 3 in pipes and mufflers (my car will have 2 1/2 in pipes)... did Chrysler run their tests with open pipes?

I was expecting to see around 400 HP, what am I missing?

[moparmarc]

One more thing:

I know a lot of people will say I can get better numbers with aluminum heads and intake, or headers, or whatever, but I'm looking to keep the car stock. I know I can up the power with better aftermarket parts but want to know why my numbers aren't higher with the parts I used.

Am I using the wrong cam? Valves too big? We didn't measure compression on the dyno (probaby wouldn't have been a bad idea).

Marc

[Clair]

What was your air/fuel ratio during the pulls? Sounds like something's missing. Cam degreed in right?

Clair

[furz4444]

I think you need to run more advance. What octane fuel were you using. You may want to check the cam timing also. I would check it with a degree wheel and dial indicator to make sure it's the right cam. Was the actual compression ratio ever determined for this motor. My first though would be a fuel delevery problem. How much fuel pressure do you have at the carb at WOT. If you re-used your pump drive rod sometimes those can have quite a bit of wear and you wont get full fuel pressure

[moparmarc]

We ran an electric fuel pump off the dyno, so I'm not sure what the pressure was set to.

I didn't degree the cam at all, just set the marks to match up. I can pull the cover and take a look to be sure it's still lined up.

[sanborn]

Welcome to the "Factory HP Myth". Some factory HP number are close to actual production numbers, some arn't. Actually, yours are closer than most.

GM numbers tend to be vastly overstated, Ford is just about as bad. Mopar numbers vary a lot but are more accurate than most.

How do the factory get their HP numbers? By dyno tests, yes but by testing many different engines, without parasitic drag of alternators, maybe even water pumps. Are the exhaust open---you bet! And all it takes to get a HP change is to change the correction factors(to sea level for example) and a 5-8% change is easy.

Not trying to be negative, but you have built essentially a stock engine. Yes, you have larger than stock exhaust valves and slightly more cam---but will the rest of the engine take advantage of those changes. Maybe not with the stock exhaust system with mufflers. And check real close the lifters to make sure they aren't bleeding down at higher RPM causing a loss of lift.

[72Challenger]

One important factor to consider here is that the SAE spec used for measuring horsepower has changed since 1967. The baseline for temperature and air density is different now, and will lower ratings from what were used previously. Did you have accessories mounted on the engine? Air cleaner, mufflers? Gross HP ratings were measured without those things, and weren't used in 1967 either. I'll bet your engine is making the same power as the factory got in '67, you are just measuring it differently, more realistically.

[ehostler]

I agree with 72Challenger.

[perfmachst]

hello, pulling the timing cover and checking marks won't do you much good.
you have to mount a degree wheel on crank, dial indicator on push rod, to find where cam centerline is in relationship to the piston. another thing, no mention of ring combination or type. he's right, no factory motor ever put out it's rated number. the motors were hand built, ,tested in a controled room, no accessories. plus, you didn't mention piston/wall clearances. ring combinations and bore finish does make a huge difference in power output!
just food for thought

[rumblefish360]

Mark, I'm not really a big block guy. So I have a question or 2.

1st;
I'd like to say, I think the valves, 2.08 are to small for a 440, and this is the main key to power I think on your engine. The cam is still mild, stock rocker ratios are not as what there advertised to be, and the factory intake needs to be swapped out. In general, I think there lumps and not really good to use unless the wallet says different. There not bad, but vs. todays intakes, the stock ones are best swapped out even in low duration cams.
Exhaust manifolds; they can use a cam with 8 - 10 degrees of exhaust or more over the intake. Yes, even the factory hi-po's.

Questions;
How big is the carb. (I don't have my book handy.) I suggest a 750 cfm unit if the current carb is smaller than that.
A RPM intake would be a good match to the cam.
Re-curve the distributor.
And MoPars HD rockers at a min. if not ductile adjustables.

[moparmarc]

Originally Posted by 72Challenger

One important factor to consider here is that the SAE spec used for measuring horsepower has changed since 1967. The baseline for temperature and air density is different now, and will lower ratings from what were used previously.

That's true... the results were corrected for temp and barometric pressure (not sure the exact numbers, but it's on the printouts). I really wasn't too sure how that affected the numbers listed, though.

We did run without air cleaner, water pump (electric pump), or alternator.

[moparmarc]

Originally Posted by rumblefish360

Mark, I'm not really a big block guy. So I have a question or 2.

1st;
I'd like to say, I think the valves, 2.08 are to small for a 440, and this is the main key to power I think on your engine. The cam is still mild, stock rocker ratios are not as what there advertised to be, and the factory intake needs to be swapped out. In general, I think there lumps and not really good to use unless the wallet says different. There not bad, but vs. todays intakes, the stock ones are best swapped out even in low duration cams.
Exhaust manifolds; they can use a cam with 8 - 10 degrees of exhaust or more over the intake. Yes, even the factory hi-po's.

Thanks for the info. The intake valves are stock... I enlarged the exhaust because stock were tiny. For cam, I tried to keep the overlap narrow, though my car has no brake booster.

Originally Posted by rumblefish360

Questions;
How big is the carb. (I don't have my book handy.) I suggest a 750 cfm unit if the current carb is smaller than that.
A RPM intake would be a good match to the cam.
Re-curve the distributor.
And MoPars HD rockers at a min. if not ductile adjustables.

Unsure of carb CFMs, but guessing 700 - 750. The intake size is smaller on this carb than the later AFBs or AVS.

[jelsr]

The maxi's were rated at 425 using 2.08 valves and I don't think the 14 extra inches would have that big an effect. I am wondering why the detonation at 32 deg with a zero decked closed chamber head setup.

[daredevil]

Recurvethe distributor and some race fuel In 67 they ran leaded high test

[72Challenger]

Originally Posted by moparmarc

the results were corrected for temp and barometric pressure (not sure the exact numbers, but it's on the printouts). I really wasn't too sure how that affected the numbers listed, though.

Results are always corrected to a baseline, but the thing is that the baseline has changed. I don't know the exact numbers off the top of my head, but the standard used in the 60's was cooler and denser than the baseline in use today. This would give higher readings then, than you would get from the exact same engine if measured using today's standard.

The other factor has already been brought up, that your choice in gasoline is limiting your full potential. With a mix of some racing gas that will allow full advance, you may find another dozen horsepower at the top end.

[pishta]

Factory HP ratings were from blueprinted motors. I bet the largest variable that you are seeing with your motor over a "stock" motor is the compression. Mopar always seemed to be way off in true compression like a whole point down on a production line head. 10.5:1 340? try 9.5 and so on. You get guys rebuilding 340s a little over stock and claiming 400 HP, give me a break. How about the "offroad" 375/327? Lets see the dyno on that one.

[rumblefish360]

I just had a thought, it cold also be the dyno and air quality as well as correction formulas used. I don't know, just thinking outloud/straw grasping.

Marc, I'll be right back with the Carter carb/ Fed-Mougal book. I think I can find out carb size in there someplace via the carb number.

[moparmarc]

Originally Posted by rumblefish360

Marc, I'll be right back with the Carter carb/ Fed-Mougal book. I think I can find out carb size in there someplace via the carb number.

Putting on the 800cfm Holley did two things:

1. got rid of hesitation from accelerator pump
2. brought torque up throughout the RPM band, especially in the 4000 range.

Overall, though, horsepower didn't get much above what I was able to achieve with the AFB. The carb's initial pump shot was weak, so we replaced the squirters and it helped, but the hesitation was still present. Not so bad that the motor would stall out; more like a minor annoyance.

While a bit of HP might be gained by replacing the carb, I doubt it would do much with that stock intake so I'm willing to deal with the hesitation.

Marc

[moparmarc]

Originally Posted by pishta

You get guys rebuilding 340s a little over stock and claiming 400 HP, give me a break. How about the "offroad" 375/327? Lets see the dyno on that one.

Ain't that the truth. I suppose I could ignore the dyno numbers, assume 375 HP plus the quoted HP gains from the cam, valves, and increased bore, and just tell people I've got 400 HP.

I've got to say, regardless of the factory numbers, 456 ft-lbs of torque is impressive.

[moparmarc]

Originally Posted by jelsr

I am wondering why the detonation at 32 deg with a zero decked closed chamber head setup.

Only sign of detonation was by looking at the plugs under magnification; I didn't hear a thing but the guy running the dyno tried different plugs and settled on 30 degrees.

I'd be willing to mix in some race gas and bring the timing up a bit, since I only drive the car a few thousand miles a year.

[jelsr]

On my 451 I was running 38* w/Chrome box and then 35* w/FBO with 10.5 CR and drum gas. Grandsons Bomber was 38* w/Chrome box and 35* w/FBO. This was with 9.5-10 to 1 and 50-50 mix drum gas and super unleaded. The Bomber has cast iron intake and exhaust on 451 and a little more cam than you are running, Racer Brown ST-21, and zero deck with 516's at .039. Other than cam it should be quite similar to your setup.

[JLM440]

Here's my thoughts, #1, that cam is too small for the comp, i'll bet you have alot of cyl. pressure, thats why it doesn't want more then 30* without trouble, #2, the 208 valve is definitely not a problem, #3, the stock intake & manifolds are hurting you, it is not hard to get 500+ FWHP & 500+ ft. lbs. of torgue out of a 440 with iron heads, I'll bet you anything, if you put a nice solid cam in it, like a 550-560 lift, 250-258 dur. @ 50, a Single plane & 1.7/8 or 2.00 headers, 800-850dp, you would be shocked at the #s, all i can say is, you need too cam it & get past that stock stuff if you want #s. i'll bet your comp. is a true 10.6-10.7 with those pistons at 0 deck & closed chambered heads, it will no run on pump anything with that cam & comp., you will have to run racing fuel, take advantage of your comp. & build that sucker, put some good stuff in it.

This was my mild 451 low-deck

400/451
steel 440 crank & rods
ARP wave locks
Molidon 7 qt with windage tray
Ross F/Ts, .009 below deck, .039 1009s
mildly home ported 906s, 208/174 stainless valves, 90cc chambers, 9.73 comp.
Comp custom solid, 543/529 gross lift-250/256 @ 50, 108 LSA, installed at 105. 1.7/8 headers
Crane ductile iron 1.5s, weiand T/R 2 600 holleys

This set-up ran on a 50/50 mix at 35* total, it would run on 93 but i didn't want to take any changes, plus i love the smell of race fuel.

At 3100 race weight & horrible 60ft times
1.61 60ft, 10.87 @ 123.58 in the heat.
shifting at 5800
I never had it on a dyno, but according to the calculators & the builders it was making over 500 HP & over 500 lb. ft of torgue to run these #s

[MrChemist]

JLM440, you must have missed the second part of the original post.

Originally Posted by moparmarc

One more thing:

I know a lot of people will say I can get better numbers with aluminum heads and intake, or headers, or whatever, but I'm looking to keep the car stock. I know I can up the power with better aftermarket parts but want to know why my numbers aren't higher with the parts I used.

Am I using the wrong cam? Valves too big? We didn't measure compression on the dyno (probaby wouldn't have been a bad idea).

Marc

[rusty duster]

Put some big valves in it,port them heads and wake that thing up,run the fattest exhaust system that will fit under the car!Don't let anybody tell you back pressure is a good thing.

[JLM440]

Originally Posted by MrChemist

JLM440, you must have missed the second part of the original post.

Ya, didn't see that, but still, i think he built an engine with too much comp. for the rest of the combo, the #s he got are about what could be expected, he either needs to take comp. out of it or put a different cam to calm down cyl. pressure & do some bowl work & polish the chambers. I had a 440 that was .030 over with TRW six-pack pistons, 906 heads that i milled .090, they CCed at 67-68, with steel shim gaskets, the comp. was 12.2, TM7 intake with headers, it ran pretty good with a 509 (12.4s & 110 at 3700 ft.), but when i sold the engine to a friend, he didn't want that much cam, i warned him about the comp., so i put a mild cam in for him, we put it in his 67 belvedere, that engine pinged & rattled & lost so much power, didn't even feel like the same engine, we had to put the total timing at 26* & it still had slight pinging, but he lived with it, one day we put 110 race gas in it, it ran so much better with the timing back around 35*, but to me the only thing it was good for was pulling a trailer.

That guy steve Dulutch, i think thats his name, did an article a few years back on the 440 375 HP Magnum build, they built it to specs to check the #s to the claims of "375" horse, it dynoed at 349 HP & around 460 something lb. ft. torque, the comp. was around 9.4.1 with 90cc 906s, they figured that the higher #s might have been from treaking with it at the track, closing off the heat cross-over, jetting the carb & playing with timing ect. this was on 93 octane.

[darktone]

Originally Posted by JLM440

Here's my thoughts, #1, that cam is too small for the comp, i'll bet you have alot of cyl. pressure, thats why it doesn't want more then 30* without trouble, #2, the 208 valve is definitely not a problem, #3, the stock intake & manifolds are hurting you, it is not hard to get 500+ FWHP & 500+ ft. lbs. of torgue out of a 440 with iron heads, I'll bet you anything, if you put a nice solid cam in it, like a 550-560 lift, 250-258 dur. @ 50, a Single plane & 1.7/8 or 2.00 headers, 800-850dp, you would be shocked at the #s, all i can say is, you need too cam it & get past that stock stuff if you want #s. i'll bet your comp. is a true 10.6-10.7 with those pistons at 0 deck & closed chambered heads, it will no run on pump anything with that cam & comp., you will have to run racing fuel, take advantage of your comp. & build that sucker, put some good stuff in it.

This was my mild 451 low-deck

400/451
steel 440 crank & rods
ARP wave locks
Molidon 7 qt with windage tray
Ross F/Ts, .009 below deck, .039 1009s
mildly home ported 906s, 208/174 stainless valves, 90cc chambers, 9.73 comp.
Comp custom solid, 543/529 gross lift-250/256 @ 50, 108 LSA, installed at 105. 1.7/8 headers
Crane ductile iron 1.5s, weiand T/R 2 600 holleys

This set-up ran on a 50/50 mix at 35* total, it would run on 93 but i didn't want to take any changes, plus i love the smell of race fuel.

At 3100 race weight & horrible 60ft times
1.61 60ft, 10.87 @ 123.58 in the heat.
shifting at 5800
I never had it on a dyno, but according to the calculators & the builders it was making over 500 HP & over 500 lb. ft of torgue to run these #s

I would guess you were making 600+ HP to run a 10.87. Probably closer to 650HP.

[Rug_Trucker]

Originally Posted by JLM440

That guy steve Dulutch, i think thats his name, did an article a few years back on the 440 375 HP Magnum build, they built it to specs to check the #s to the claims of "375" horse, it dynoed at 349 HP & around 460 something lb. ft. torque, the comp. was around 9.4.1 with 90cc 906s, they figured that the higher #s might have been from treaking with it at the track, closing off the heat cross-over, jetting the carb & playing with timing ect. this was on 93 octane.

Gee Whiz! Mopar Performance built a 383 to factory spec and got 337HP for an engine rated at 335.

Did you forget to put the vacuum cleaners on the exhaust?

[moparmarc]

Originally Posted by JLM440

That guy steve Dulutch, i think thats his name, did an article a few years back on the 440 375 HP Magnum build, they built it to specs to check the #s to the claims of "375" horse, it dynoed at 349 HP & around 460 something lb. ft. torque, the comp. was around 9.4.1 with 90cc 906s, they figured that the higher #s might have been from treaking with it at the track, closing off the heat cross-over, jetting the carb & playing with timing ect. this was on 93 octane.

Those are about the numbers I'm seeing; 350 HP, 460 ft-lbs torque. I'm running 915 heads so the comp is probably closer to 10.1:1.

Right now, my thoughts are to try the motor with a 50/50 race fuel mix and 32* advance (maybe even 35*, depending on how it likes the race fuel).

[JLM440]

Originally Posted by darktone

I would guess you were making 600+ HP to run a 10.87. Probably closer to 650HP.

Not even close, that kind of horse power would have put me in the 9s

[JLM440]

Originally Posted by Rug_Trucker

Gee Whiz! Mopar Performance built a 383 to factory spec and got 337HP for an engine rated at 335.

Did you forget to put the vacuum cleaners on the exhaust?

I'm sure they tweek with it some, Steve didn't tweek anything at all, he wanted the true #s, plus the 383 doesn't have the torque of the 440, the 383s a strong runner no doubt, but the 440 will still have a 50 horse & 50 ft. lb. of torque advantage in stock form IMO.