400 BB Mopar dyno test

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sr71mopar said:
This is the type of build I'm looking for but with a 440. I wonder what the difference would be?
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More Tq, and a bit narrower power band. The 440 needs more cylinder head to rpm that high with the thumpr cam. You could use the next larger cam, or go with the 275HL cam which is one of my favorites.
 
More pics:
 

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Sweet. I was looking at that cam. Nice to know it it's a good choice for the type of build I was looking to do.
Thanks for this thread.
 
ou812 said:
Considering the stock rockers, and almost stock heads yes I'm happy. Made good tq too considering the header was a bit large and stock stroke is only 3.380.

I was worried we wouldn't make 400 HP with the stock rockers...it sounded really good at 6000rpm!
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So what would say is the next most cost effective couple changes to this motor that you would have made to get more HP without losing reliability (street/strip application)?

Ma Snart
 
A 1.6 or even 1.7 Hughes rocker would be the next step for me. After that, I'd look hard at the eddy heads. For the cost, I think they would be a definite plus. I would not overlook the Victor std port heads either....
 
eddy heads would probably lower the weight 70 pounds and up the horsepower by 70. but cost lots of dough
 
ou812 said:
A 1.6 or even 1.7 Hughes rocker would be the next step for me. After that, I'd look hard at the eddy heads. For the cost, I think they would be a definite plus. I would not overlook the Victor std port heads either....
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Eddy heads out of the box or pay to have them ported?
 
I'd have to agree - heads and good rockers too. One thing to notice is the power curve. Torque is peaky with the 3.38 stroke and heads wont change that much. If it's in a street car and you can work the compression and quench from the get-go, I'd do so. The torque is low in the rpms where a street car uses it most - below 3K rpms. This is the main reason why the 383/400 platform isn't used more. At least IMO anyway.
 
moper said:
I'd have to agree - heads and good rockers too. One thing to notice is the power curve. Torque is peaky with the 3.38 stroke and heads wont change that much. If it's in a street car and you can work the compression and quench from the get-go, I'd do so. The torque is low in the rpms where a street car uses it most - below 3K rpms. This is the main reason why the 383/400 platform isn't used more. At least IMO anyway.
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If you look at the number graph you'll notice the TQ curve is actually NOT peaky but holds above 420ft. lbs. for 1300rpm! Not bad when you consider the mild heads...the graph makes the TQ curve look peaky but it's not. Infact it's above 400ft. lbs. for most of the pull!
I was very surprised at the tq curve and I'm sure with a smaller header it would have been better but may have cost some HP which may or may not be what the end user wants?

I also didn't advance the cam because of the close piston the head problem with an open chamber head. With a closed chamber, and quench the TQ should have picked up everywhere with some added HP.
But for a budget deal, to have this much power and tq for under 5K is pretty reasonable!!
 
Tq is over 400 ft/lb's from 3000 to 5500 rpm! Stump puller if you ask me...more torque than a 360 would produce,but doing it with less stroke and therefore more upper rpm potential.

Heck,this motor is cheap to upgrade to a 451 stroker if you need more tq!

IMHO,the 400 is the most underrated of all mopar engines.Yet it has the best base platform of them all..
 
400 lbs. of TQ rising to 442 from 3000 - 5400 is a nice curve with the short stroke. I think the graph has a squished look and that would be the reason Moper said it looked "peaky."
 
Cevidicus said:
What is the actual cost of this engine as pictured top to bottom?

And thanks for posting.
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It's just under 5K without headers, but with everything else! That includes the ready to run dist. from MSD which is not cheap.
Now if the heads required more work, like guides and seats it'll be about 250.00 more, or just go with eddy heads OOTB and gain quench. You'll have to mill them though, but that's included in the original 5K price so it's a wash.
 
Thanks again OU812 for the great info

When is your next build dyno run?? LOL!!!

Ma Snart
 
Salty Dog said:
400 lbs. of TQ rising to 442 from 3000 - 5400 is a nice curve with the short stroke. I think the graph has a squished look and that would be the reason Moper said it looked "peaky."
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No, not really. I think for street engine it is a peaky torque curve. I've attached a dyno test from a Challenger (new one) I found online. This is what a flat toraue curve looks like. The 400 will need gears to not feel sluggish, especially in a street car with 3 series gearing and a convertor around 2500.
 

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moper said:
No, not really. I think for street engine it is a peaky torque curve. I've attached a dyno test from a Challenger (new one) I found online. This is what a flat toraue curve looks like. The 400 will need gears to not feel sluggish, especially in a street car with 3 series gearing and a convertor around 2500.
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I don't know...if you plot out the TQ from our 400 and spread it out like that graph I think you'll see what I mean. We had a wide spread of over 400ft. lbs. from 3000rpm to 5500rpm! It peaked at 5700rpm so...?
 
ou812 said:
I don't know...if you plot out the TQ from our 400 and spread it out like that graph I think you'll see what I mean. We had a wide spread of over 400ft. lbs. from 3000rpm to 5500rpm! It peaked at 5700rpm so...?
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I agree. It's a pretty flat curve and well over 400 ft/lb'. I'd like to see it in an A body,and run an the track!
 
The step on the IMM is 300rpm. If you take the numbers off the sheet (not the graph) and note the change over 500rpm they look like this:
3K - 3.5K 12
3.5K - 4K 19
4K - 4.5K 2
4.5K - 5K (-2)
On the one I posted:
3K - 3.5K 14
3.5K - 4K 4
4K - 4.5K 2
4.5K - 5K (- 8 )
Not an exact graph to trace both curves, but the torque on the 400 comes up fast, and drops off fast. At least by my perception anyway. It's again just my opinion, but I'd prefer a very flat torque curve for a street engine and that one isn't very flat.
It's not bad power to get. Its not a crappy engine by a long shot. But it IS demonstrative of a short stroke build... ie, steep power curves and peaky rpms. It will need to be coupled to gearing and convertor that puts it up in the 4K range to really be effective. That was my point.
 
I dunno moper.We are talking about over 400 ft/lb's from 3000 to 5500 rpm.And the lower rpm range is a bit soft yes,but in a light A body Im thinking maybe 3:55 to 3:91 ish gears and the tq might flash lower than you think in a light car..
 
Well, IMO, I thought the graph looked squished a bit. The short stroke engines are peaky since that is kind of how they are as compared to a longer stroke engine. I do think the graph shows a quick rise to the torque like Moper say's it does for that peaky spike in torque, though, it may not feel as such when installed and driving.

IDK, I think I'd like it in double duty car.

FWIW, the graph shown in the click'y at MRL's 505 thread seem's to be stretched out. Maybe it is just the way it all looks. No sense in complaining on this issue of the graph.

Not the torque line of the 440, longer and flatter. OK, this isn't a apple to apple compare.

http://www.forabodiesonly.com/mopar/showthread.php?t=180005
 
So what exactly are you going to do with that engine now (or did I miss that somewhere before?)

Going to sell it, stick it in a car, or put iti in the warehouse?

Ma Snart
 
moper said:
The step on the IMM is 300rpm. If you take the numbers off the sheet (not the graph) and note the change over 500rpm they look like this:
3K - 3.5K 12
3.5K - 4K 19
4K - 4.5K 2
4.5K - 5K (-2)
On the one I posted:
3K - 3.5K 14
3.5K - 4K 4
4K - 4.5K 2
4.5K - 5K (- 8 )
Not an exact graph to trace both curves, but the torque on the 400 comes up fast, and drops off fast. At least by my perception anyway. It's again just my opinion, but I'd prefer a very flat torque curve for a street engine and that one isn't very flat.
It's not bad power to get. Its not a crappy engine by a long shot. But it IS demonstrative of a short stroke build... ie, steep power curves and peaky rpms. It will need to be coupled to gearing and convertor that puts it up in the 4K range to really be effective. That was my point.
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You may just not be accustomed to the DTS graph appearance. That curve when used with Superflow's WynDyn software would look much smoother. It's just an appearance thing--I am not debating the actual torque output. J.Rob
 
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