Do these 440 dyno numbers look right?

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sbh126

sbh126

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Had my 440 tuned on the dyno today and drivability really improved but my numbers are a little below what I expected. About 350 HP and 405 ft lbs at the wheels. HP begins tapering off around 4500 and drops at 5500. Is this about right for my combo or do I have an issue? My setup is as follows;

rebuilt 440 with 1000 miles on it.
70' forged crank and reconditioned rods
KB 237 pistons
10.6 compression and running on 93 octane
Stealth Heads w/ 1.6 rockers
Eddy RPM dual plane intake
Atomic EFI system
MSD 6AL2 ignition
Comp Cam Xtreme Energy Hi-Lift .545" Hydraulic flat tappet
110* lobe separation angle (cam is supposed to make power through 6000 RPM)
Comp cams dual valve springs (for greater than .510 lift)
1 7/8" fenderwell headers into 3" exhaust.

Anything I'm missing?

I should also mention I had good fuel pressure and A/F ration all the way through 6000 RPM. Engine temp was constant at 180*. Total timing is at 35*.

Is it possible my valves are floating even with the quality springs? What am I missing? Or do these numbers look about right for my combo?
 

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I dont know. Was there a reason you didnt include the cam duration? Looks kinda small. 235ish? Plenty torquey.
What I do see is huge torque at/from 2200rpm. Just what you need for street duty. Should be a blast, if thats what you built it for.
Put it into a Magnum, or C-body, and watch the jaws drop, when you roll into it at 30 mph.If I see you in my neighborhood, Im going home.lol
 
I'd like to see what the experts say, but the curve looks a bit erratic at 5200 up. springs spec's for .545 running at 1.6? Lifters that can't keep up, coil and/or ignition that can't keep up, exhaust volume are a few things I have run into with a curve like that dynoing Hd's assuming the timing is dialed in.
 
I see valve springs givin it up. You say springs for "greater than .525 lift" but are they the RIGHT springs for that cam?
 
Is this an automatic? The torque converter will have a large effect on the numbers. A chassis dyno is best thought of as a tuning tool. I don't know that you should be too concerned with the power falling off at a lower rpm than you expected. Maybe driveline losses are becoming more significant at that point, especially if tested in high gear. I would ask the dyno operator, he should know something, I would hope. Lot of variables with a chassis dyno. Take it to the track and see how it runs.
 
These are the older style stealth heads. Although I'm not too sure what they changed. And this is a 4 speed car btw.

Any suggestions on alternate springs? If the springs were struggling would it be audible?

Any way I can rule out the ignition components without just replacing them.
 
Even without the CNC machining, those heads flow well enough for the 420ish flywheel hp you have. Im with Rusty on this one.
 
Comp says that cam needs either the 924-16 springs or the 26120-16 springs. If it doesn't have either of those, that could well be your problem.
 
The camshaft would be the Comp Cams XE285HL 241/247 @ .050". With that engine/cylinder head design that is exactly where I would expect the horsepower to drop off and what I would expect in rear wheel horsepower and torque.
 
That seems soft to me. Around 410hp with heads that should go 250 out of the box and a cam past .500 lift? No way. Something's amiss. Sounds like some of the details are sketchy. Were the heads corrected? Were the springs and retainers replaced? How many miles on it? It seems to me to break up early - does the Atominc system learn or do you tune it?
 
Don't worry about the ultimate hp numbers. There are plenty of 11 second cars out there with "only" 350 hp to the wheels. Too many variables. Just the way the car is strapped to the dyno will affect output. I read a story once where they took a car to three different dynos. The difference between best and worst was almost ONE HUNDRED horsepower.
 
Sorry, I made a mistake with the second spring number. I corrected it.
 
forphorty said:
Just the way the car is strapped to the dyno will affect output. I read a story once where they took a car to three different dynos. The difference between best and worst was almost ONE HUNDRED horsepower.
Click to expand...

Also true... No dyno is infallible. They're simply tools.
 
RustyRatRod said:
Comp says that cam needs either the 924-16 springs or the 26120-16 springs. If it doesn't have either of those, that could well be your problem.
Click to expand...

So I found the original box the springs came in and I do indeed have the 924-16 springs. And I did installed the inner springs after engine break in.
 
moper said:
That seems soft to me. Around 410hp with heads that should go 250 out of the box and a cam past .500 lift? No way. Something's amiss. Sounds like some of the details are sketchy. Were the heads corrected? Were the springs and retainers replaced? How many miles on it? It seems to me to break up early - does the Atominc system learn or do you tune it?
Click to expand...

What do you mean by "corrected"? I was a little worried about the quality of the heads when I first got them so I had my machine shop look them over. I think they installed higher quality valve guides and seals. The springs are basically new and I have the correct retainers. The whole set up has about 1000 miles over the last few years.

I do believe that the Atomic EFI has some learning capabilities but I'm not exactly sure what all that entails. I'll have to research it. But the A/F ratio was 12-13 ish all the way up through 6000 RPM. So I don't think that is the culprit.
 
I may contact Comp and see what they have to say about my combo. From what I'm reading I have the right spring/cam combo. I just don't see what else it could be. maybe I'll buy the other set of springs that was mentioned and see if things change. They are rated at 370 in lbs where the springs I have now are 350 in lbs.
 
You guys crack me up. You make horsepower pronouncements and valve spring failures without knowing installed height or spring pressures, you don't know what lifters he is using or the lifter preload, oil pressure, leakdown %, cranking compression, installed camshaft timing, you're using the book compression figures from the Keith Black site, you don't know the cylinder head cc's, deck heights or the cylinder head flow figures. You don't know what dyno he was running on and how it was loaded. If you think most chassis dynos drop only 15-18% with a manual transmission you've never run on one after you've gotten flywheel dyno figures.

We've got over 100 dyno pulls on 440 engines using the XE285HL camshaft with different cylinder head flows and I've posted many of our results.

So why don't I just say do this and it will fix it? Because I've gone damn near broke figuring it out for myself. Sorry, yep sometimes I'm selfish. I post the things I do, so you can look at them, use your brain and figure something out for yourself.

http://www.forabodiesonly.com/mopar/showthread.php?t=261378

http://www.forbbodiesonly.com/moparforum/showthread.php?64775-Pop-s-440-is-near-ready-to-dyno&highlight=pop%27s+440

Early OOTB Stealth actual flow figures.

.100........66
.200.......142
.300.......205
.400.......240
.500.......255
.600.......267

Now in the above links are the actual flow figures and what it took to get it to rev and make the horsepower you think this engine should be making. I've wasted enough time, I've got valve jobs to do.
 
Jim, I brought up valve springs for two reasons. First, IMO the power ant torque fall off too soon. Second, he said clearly the springs he used were "good for over .525 lift."

That's a very vague statement, so I gave an internet guess based on the two things I saw and noted. I also said that if he does not have the correct spring, that could be the problem.

Again, just another internet guess. I don't have a dyno in my back yard to gain the years of experience someone like you has, so I have to base my answers and opinions on my very limited knowledge.

Everything you say is true. We basically know nothing about his combination. None of the details you brought up. I guess maybe I enjoy trying to help too much.
 
You are very helpful Rob. The valve train does appear to be unstable there. It's not the springs themselves. I still love you Bro.
 
sbh126 said:
What do you mean by "corrected"? I was a little worried about the quality of the heads when I first got them so I had my machine shop look them over. I think they installed higher quality valve guides and seals. The springs are basically new and I have the correct retainers. The whole set up has about 1000 miles over the last few years.
Click to expand...

Early Stealth heads had issues with chamber size & shape (most head gaskets wouldn't seal properly), guides, springs, retainers, locks, and quality of valve job. My concerns are twofold: first the valve springs, retainers, and locks were/are known to be fairly cheap crap on Stealths. Lift is not the spec that one should be using to see if a spring will work or not. Pressures (valve on the seat, and at max lift or "over the nose") are what you need to know and match to the cam. If you did not replace the springs with the ones Comp says to use (or someone's equivolent) then you already have a problem. The HL series Mopar cams need valve spring to properly rev. They also need the right preload. Additionally as The Omnipotent One IQ mentioned you didn't have enough detail to really say if there might be other issues or to demonstrate a real understanding of your engine. I don't agree with much of what he spewed and I think there's more in it should you choose to investigate. I will tell you had I built it, I'd be wondering what it does at the track because I'd not be satisfied with what the dyno said so I'd want to remove that as the indicator of output.
 
moper said:
... If you did not replace the springs with the ones Comp says to use (or someone's equivolent) then you already have a problem. The HL series Mopar cams need valve spring to properly rev. They also need the right preload....
Click to expand...

Springs, retainers, keepers were all replaced with what comp recommended.

When I had the motor out recently I decided to retorque the rockershafts and adjust the preload on the lifters. I'm wondering if I may not have enough preload and if this is the case would I see issues similar to what I'm having?

First off I'm running the adjustable 1.6 roller rockers that 440Source sells and the Comp Pro Magnum lifters(recommended by 440 Source)

When I set lifter preload I tightened them down to zero lash and then gave them 1/8 turn more as per Comps instructions found here; [ame]http://www.compcams.com/Instructions/Files/COMP4-115.pdf[/ame]
This magazine article states that I should go 1/2 turn past zero lash. http://www.dragzine.com/news/how-to-set-and-adjust-valve-lash-like-a-pro/

I'm inclined to follow Comps instructions but I'm interested in what others are setting their preload to.
 
So I have an extra adjuster and locknut and decided to measure how much 1/8 turn actually is. I'm showing roughly .010 of an inch. A lot of what I'm reading says preload should be between .020 and .060.

What are the effects of too little preload? In my mind having too much preload would cause valves to possibly stay open while too little would maybe be noisy. Opinions?

Also if my valves were floating wouldn't I be getting some kind of backfiring going on?
 
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