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Old 08-21-2009, 06:42 PM
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help me build a strong high reving small block 400 mopar

i need a high revving race application 400 small block mopar. i have a good block thats complete and runs but its going into a chrysler newport derby car. i dont have a huge budget. i want it to rev high but i want it to last more than 1 race. any help greatly appreciated.

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Old 08-21-2009, 07:39 PM
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What engine are you talking about because there is no such thing as a "400 small block mopar" unless you build a stroker engine out of a 340 or 360 LA series engine. Are you referring to the 400 "B" engine(short deck big block)???
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Old 08-22-2009, 12:31 AM
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you can stroke a sbm to 406 to 408 CI depending on what back you choose, cheap I think not. How big of track are you on? If its anything near 3/8 of a mile you are not going to keep it in the high rpm range
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Old 08-22-2009, 01:12 AM
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I'm curious what you are going to do w/a "high revving race application 400"? Is this for a particular class or some such? Can the engine be larger, or is it limited to 400 CID?

I ask, because there are ways to get good power out of a 400 MOPAR engine, but it usually involves going bigger, like stroking it to 451 or larger (much larger in some cases).

The 451 has a (relatively speaking) short stroke for it's size so revving it isn't out of the question by any means- but it can get costly because the rotator and valve train needs to be able to stand up to the stress.

Some more details of what you are after will help.
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Old 08-22-2009, 10:11 AM
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i can run whatever motor no matter how big. its a dirt track. yes im refering to the B engine. im usualy not a mopar guy, im a chevy guy but this is what i have to run right now.
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Old 08-22-2009, 01:26 PM
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That is a B engine and not a small block. As you know even in BBC they are not the highest revving engines either. I would stick to the stock 400 and modify the other parts of the car suck as the rear gears to get you out of the corners better and suspension work
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Old 08-22-2009, 03:08 PM
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I think that you would be better off using a 360 and stroking it. I think that the 400 may take to much time to build power as it has a fairly long stroke. Also the added weight of the big block may be a hindrance.
The 400bb and 440 rb make excellent drag motors do to the massive torque that you get but I would think that if you needed to get on and off the gas as you would in any circle racing that a quicker revving engine along with proper rear end gear selection would be the way to go.
Just my 2 cents.
If all you have is the 400, I would concentrate on the gearing. You are not going to be able to easily or cheaply make it rev freely. You would have to lighten the recipricating mass (pistons, flywheel, rods, etc) to get it to rev quicker.

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Old 08-22-2009, 03:32 PM
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Do you mean derby as in demolition derby or is this a circle track car?
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Old 08-22-2009, 03:33 PM
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And what is your budget?
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Old 08-22-2009, 06:59 PM
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I can't even imagine running a Newport on a circle track Those things are so heavy & tough many DemoDerby tracks banned them. Said they were too tough. I have a 71 Newport w/400 myself, talk about a Tank.
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Old 08-22-2009, 07:33 PM
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The 400 B does not have a long stroke- it's VERY oversquare at 4.34" bore x 3.38 stroke. This is less than a 267/305/350 SBC.

Even w/the 440 stroke length crank, it's then the same stroke as a 383/400 SBC @ 3.75", except the displacement jumps to ~450 cid- w/the 3.75" stroke and a 0.060" over 440 piston, or what ever it is MOPAR guys use these days.

If I were gonna race a MOPAR, it would be an LA engine, though. No need to make it any more difficult than it has to be, IMO.
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Old 08-22-2009, 07:40 PM
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Found this on another forum

Not a 400, but worth considering:

First we'll start with a 318 block (re builder) as they are plentiful, then we'll get a 360 crank and turn the mains down to 318 specs. We are going to use the factory 6.123 rods, and low compression 318 pistons which are 1.72 compression height. Next we are going to align hone and deck the block to clean and square deck all 4 corners. This is more info on what to do and not priced as price can vary. So now we have a block that measures 9.570 after decking .030. As most used blocks are generally out .020 to .030 from core settling and thermal cycles, some may be taller as they are only castings. Now this is where we are 9.570 actual deck height less the rod length, and the compression distance, and stroke. Half of 3.58 is 1.79 on stroke.

9.570-1.79=7.780 minus rod length of 6.123= 1.657 less the compression distance of 1.72= .063 above the deck. Now we'll take a corteco head gasket of .055 which now we have .008 above the gasket. Or for racing use a .022 mopar gasket and have .033 more compression for a total of .041 above the gasket.

Next we'll go to the heads, for a 349 CI we'll need the 360 heads to get enough port volume and air flow. By my calculations we'll need 166 cc's of port volume and 266 cfms to supply enough air and we'll be using the 1.88 intake valves and 1.60 exhaust valves to help keep the port velocity up. This is fairly easy to get when mildly ported. As for the chambers they have been in the .095 to .105 in chamber depth stock, at the area where the quench would be. So now we have a positive deck of .041 with the gasket in place, or .008 depending on which gasket is being used. In this case we'll use the thinner gasket so we'll be .041 above the deck. Now the deck is .095 less the positive deck of .041 and we now have a quench of .051 so we'll deck the heads to true them up, generally this takes .010 to .012 so now we have a total quench of .039 to .041 which is what most would like to have as total quench. This now yields 12.21:1 this is why this is a race setup, the thicker head gasket will yield about 11.5:1. If it doesn't take as much to deck the heads or the block then this will change to a lower compression and be more street-able.

Next we'll go to the camshaft, for our example were using a comp cams .540 /300 drag race cam with 255 @ .050. For this cam the pistons will have to be notched, so we notched them .200 as the pistons are forged and are .400 thick. This is about as far as you can go safely. We'll be using 1.6 ratio rockers so the lift is .576 but the lash is .026 and we have to subtract .010 for the loss of valve lift due to the grind for mopars. Now we have a actual net lift of .540. So with the valve reliefs we should have .100-.130 valve to piston clearance depending on the gasket thickness.

Next we'll go to the intake manifold, this I leave up to the end user for what they want. But for our application we used the M-1 intake as we had it, from another engine. And we'll top it off with a Holley carb 850 cfm with 83 and 88 jets and no power valves.

So now to some this up we have a 318 with a 360 crank and stock rods and pistons of the forged type. Stock type heads with work done and a M-1 intake and a street type headers. A good cam and valve train and oiling system to support this type of engine. The preliminary tests have shown 578 HP @ 6500 and 507 TQ @ 5000, and 506 FT. lbs. @ 4500. So it has a nice broad torque curve. Even in lessor trim it should still have over 500 HP and 450 in torque and be street able.
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Old 08-23-2009, 06:52 PM
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you guys figured me out its going to be a derby car i just didnt want to get drap for spending a lot of money on a car thats gonna get smashed and broke and bent on a regular bases. its going to be a race car not a finale car.
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Old 08-23-2009, 08:17 PM
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ok, I'll ask again.
Do you mean derby as in demolition derby or is this a circle track car?

Son, you have to realize YOU know what you're going to do with the car, whereas I have no clue and have no idea what a finale car is.

Is the car to be used on a circle track or a figure 8 track or in a free for all demolition event?
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Old 08-23-2009, 08:32 PM
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Quote:
Originally Posted by techinspector1
ok, I'll ask again.
Do you mean derby as in demolition derby or is this a circle track car?

Son, you have to realize YOU know what you're going to do with the car, whereas I have no clue and have no idea what a finale car is.

Is the car to be used on a circle track or a figure 8 track or in a free for all demolition event?

Tech....I think he said it here...

Quote:
Originally Posted by dman16
you guys figured me out its going to be a derby car i just didnt want to get drap for spending a lot of money on a car thats gonna get smashed and broke and bent on a regular bases. its going to be a race car not a finale car.
I think he's planning on smashing it up on regular bases...
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