The 451

[Moulder]

I'm a considered somewhat of a newbie to mopars. I have done quite a bit of reading on them, but haven't had much expsure to them. Well I finally got myself a mopar. I have been looking at all the engine possibilities. I found info about this motor and found it interesting. I would like to hear from people that have this motor. I haven't heard that much talk about the 383 & 400, are they not to good? I wanted to go with a 400 over the 440 because of the smaller external size (read headers), and more people are likely to race a car that has 383 on instead of 440.


Other info I found out about it or need:

the rod journals can be offset ground to big block chevy size (2.200) to make a 470ci (plus an over bore). What rod length would be used for this? I heard that Manley rods work very good for this.

What kind of pistons would be used for the above mentioned combo?

Would the MP stage V cast iron heads be good for this motor?

What would be the best cam for it (street driven, maybe street raced)?

Complete roller valve train?

Intake and carb?

Anything else I forgot?



Here is some info about the car:

318 b'cuda, 8 3/4 sure grip (ratio unknown), front disc brakes

I plan on finding a complete 400 with tranny so I can upgrade to a 727

I was planning on installing subframe connectors untill I saw that you had to cut up the floor pans.

[George G. Leverette]

What year is the cuda? I have a 68 and the sub frame connectors from Mopar come in a kit with all attaching parts for about a $100.00 deoending on discount. These units screw onto the existing sub frame with no cutting after installation they can be spot welded for additional strength and security.

[Moulder]

It's a 1970.

[Brian_wo]

http://www.phoenix.net/~atc347/451/

[Jims451]

I have a 451 cid stroked 400 block that I built 6 or 7 years ago. I actually had Muscle Motors build the short block with their "race" machine work (align honed mains, decked, bored & honed with torque plates, 1/2" oil pickup, etc), and they installed a mild Ultradyne solid roller cam (251/251 duration @ 0.050", advertised 284 duration @ 0.020", and theoretical 0.620" lift using 1.6:1 rocker arms. They installe dthe cam with a cloyes timming chain and a cam button. My rocker arms checked out more closer to 1.58:1 ratio, or 0.613" lift.
The pistons are custom Ross pistons, slightly dished (about 13cc with valve reliefs) for 11.0:1 compression (with my small 65cc combustion chamber heads.)
All bolts/studs are ARP.
The short block assembled and shipped cost me about $3,500.
I used the Brodix B-1 B/S heads from Koffels place as back when I built the engine these were about the only street/strip aluminum head. This was before the Indy S/R and Edelbrock heads so I had to choose from the Indy 440-1, MP stage VI, or B-1 B/S and I used the Brodix head as it was the easiest to install (just bolt on and use the correct rocker arms, everything else for a 383/400 fits.) The Brodix head also flows nearly as well as the 440-1 head, but with stock sized ports and much better combustion chamber layout and spark plug location.
I got the heads from Koffels with their stage 1 port job, 1.6:1 aluminum roller rockers and shafts, hardened cut-to-length pushrods, ARP head studs, spark plugs and shipping cost was right at $3,000.
I really like these heads, but the new Edelbrock heads look like a great deal and appear to flow as good as the B-1 B/S and Indy S/R heads at 1/2 the cost.

I used a Milodon low profile oil pan and 1/2" pickup, a stock windage tray with the louvers open up per Chuck Senators suggestion, a Melling High Volume oil pump, and a Mopar Oil pump drive with bronze gear (needed because of the roller cam.)
Probbly another $300?

My induction is a stock Mopar M1 which works great with this combination, but I may try an INDY dual plane intake some day. My carb is a Holley 1,000+ CFM vacuum secondary Pro-Series.
Because of the decked block and aluminum heads I had to have the manifold milled 0.100" each side to fit. Estimated cost of carb and manifold $700-$800.

I use a 20-Gallon fuel cell, Mallroy 250 GPH electric fuel pump and 500 GPH filter, and a 5-port by-pass fuel regulator at the engine. The supply and return fuel lines are -8AN Braided stainless hose, and -6AN from the regulator to eash fuel bowl. Estimated cost of fuel system $700?

Exhaust is Hooker 2" Super comp headers and a TTI 3" exhaust system, estimated cost $900.

Some options on the engine are Mopar chrome timming chain cover, aluminum water pump housing and MP water pump, fuel pump block off cover, chrome dist hold down, and ARP stainless steel 12-pt engine hardware kit. Also Mopar SFI flexplate and SFI crank dampner and March pulleys Estimated cost $1,000.

Ignition is a Mallory unilite (has adjustable timming curve, but I should have used an MSD as it is easier to get to the advance curve on it.)
The Unilite triggers a MSD6AL box with a Crane PS91 coil and Jacobs ultra core plug wires. Estimated cost $500?

Torque Converter is a Dynamic 10" race unit, about 3,500 stall, and 4,200 flash stall, but very streetable with 3.55 or 3.91:1 gears. Cost about $550.

OUCH!! I just added up all the $$$ I have in the engine. About $11,250! Speed sure costs


I think the Stroker kit, local machine work on your block (I had Muscle Motors supply the block too), Edelbrock heads, a Good Hughes cam, not going crazy with ARP fastners and Aluminum parts like the Water pump housing and pump, etc you could probbly build an engine with almost as much power for way less. The fuel system is overkill and I'm sure you come up with a less expensive setup. A Stock recurved distrubitor with the MDS would save money too. The TTI exhaust was expensive, but It also was the best in terms of flow and noise reduction of three different exhaust systems I used and four different muffler types.

[Magnum440]

Jim, I got about the same size cam but its a Hughes 5056 solid. My B1-B/S heads are box stock, tho, and I use a 850 Speed demon. 440 w/Ross 10 to 1 "reverse dome". I got about 2500 mi on the engine. The Coan 10" I'm running works fine on the street. I've never had the car(72 Challenger) to the strip but will when every thing gets leagal. You are a better man than I for daring to add up your engine costs!! I know my credit card company is happy! Have you ever dyno'd your combo? Curious as to what numbers I could expect from an up-grade.~Dave

[Jims451]

I have never Dynoed the engine, but it has alot of torque
My #4,150 '71 Charger has ran 12.53 @ a bit over 110 MPH up here at Bandimere (near Denver, CO, so altitude was probbly about 6,000 ft?)
One of the weight to MPH calculators showad about 475 HP (I'm not sure if that is rear wheel HP or not.) I think you can add 15-20% to correct for the HP lost to the altitude?, so I think altitude corrected I would be closer to 550 HP and I'm not even leaning on the engine hard, shifting at 6,200 RPM.
The car is not a drag car, so it dosen't launch very hard. If I launch at over 1,500 RPM the tires will smoke This is when I run my Mickey Thompson Street ET tires. With my regular BFG radials, it is possable to smoke the tires by hitting it at speeds under 30-MPH. I have never tried real slicks on the car. I was also only running a 3.91:1 gear, but I did change it to the stock 3.23:1 for better highway driving and the car slowed only about 0.2 seconds and about 2-MPH?
The 3.23:1 gears are just a bit too tall for my converter, I would like to use a 3.55:1 gear, but I don't have one yet.
I drove the car from Denver to Pueblos PMI drag strip (about 100 miles one way) last year with the 3.91:1 gears and I think I got 10-MPG on the highway, and I don't have a vacuum advance on the distrubitor either. In Pueblos lower altitude I was in the 12.4o's even though the air was bad and I din't re-tune for the lower altitude.
I'm pretty sure a slightly larger cam would get me an additional 50 HP on the top end, but thats money I don't want to spend, and I don't want to have to put a roll bar in the car either

As for carbs, I originally had a Holley 850 DP on the car and it worked well, but I knew It was too small when I had to jet it up 12 jet sizes at this altitude. Luckely, MadCap Racing was having a killer sale on the Hollet Pro-Series 1,000+ vacuum secondary carb I now have. This carb was jetted very close right out of the box, and it is quicker on the track (I'm using the lightest vacuum secondary spring in the Holley kit), and much more responsive on the street and at small throttle openings, probbly due to the anular discharge boosters.

When I first installed the engine I had a dual 2.5" full exhaust with Dynomax Super Turbo Mufflers (The original engine was a 383.)
The new 451 sounded good with that exhaust system, but it was too restrictive and not a good match for for the 2" primary tube Hooker headers that had 3.5" collectors.
I replaced that exhaust system with a 3.5" dual exhaust system that exited under the car at the rear axle, and used Dynomax Race bullet mufflers.
The engine sounded awesome and really picked up about 0.2 second in ET, but it was way, way too loud for the street.
Over the winter I replaced the race bullet mufflers with the 3.5" Dynomax 6" welded race mufflers. These are bigger around and longer too.
They helped quiet the engine a bit, but with the exhaust exiting under the car, the car was probbly lounder inside than outside
So over the next winter I finally bought the TTI 3" exhaust system with the large 3" Dynomax Super Turbo Mufflers. Much quieter (but still sets off car alarms), and even better the car did not slow down at all. I think the smaller 3" tube having smooth mandrel bends was flowing as well or better than the 3.5" tube with the crumply type bends in the tube (Done at a local muffler shop.)

[amoparguy]

Jims451, just for grins I ran your weight and ET through an online horsepower caluclator, it showed 542 flywheel horsepower. (assuming optimum chassis set-up) Add your 15-20% altitude correction and you are looking at over 600 horsepower. I feel this is a more realistic number than the 550 you previously stated. A recent build-up in one of the Mopar rags (Mopar Muscle?) had a 440 6BBl with a much milder cam, compression ratio and cylinder head combination. If my memory serves me correctly, it made 523 horsepower on the dyno.

[Jims451]

I tend to be consertive when guessing at HP numbers. They are OK for bench racing, but the car runs what it runs. I know the engine in a real race car could be running low 11's pretty easy, but I don't have a race car or a trick aluminum drun transmission, or a 9" converter, etc. The car is mostly a stock full steel car with full interior, full exhaust, and a street car that can do SCCA solo II as well as run at the Dragstrip. It has all PolyGraphite bushings, the big "street handling", 0.96" Torsen bars, sway bars front and rear, KYB gas shocks, and an extra leaf spring added to the stock rear springs (full forwars bias to stiffen the front section of the spring.)

[Magnum440]

Oh yeah, you're a REAL conservative guy, Jim...550+ hp on the street and you do SCCA stuff with it? Seriously, thanks for all the info. Your car sounds great and it gives you alot of enjoyment. It dont have to be a 10 sec drag car to be perfect!

[Jims451]

Heck my current Project is a 1969 Coronet 500. It is going to be very clean long haul driver that I would like to take on Hot Rods Power Tour.
The car is pretty solid, but the trunk has the common rust and the rear lower quarters need replaced.
I'm stripping the body all the way down, meadia blasting it, then re-paint and re-assemble it.
I could do a quick patch on the trunk and quarters, but I want to do the car right, so I'm replacing the entire trunk floor along with new trunk extentions. What I learn on doing this car will help me when I get around to restoring the '69 Coronet R/T.

I'm going to replace the 318/904 with a mild RV built 360 (estimated 320 HP and 400 ft/lbs torque) and a slightly beefed 518 OD trans (4-clutch front drum, 3.8:1 kickdown lever, and Mopar shift kit) with a 3.23:1 sure-grip 8-3/4" rear axle.
I'll rebuilt the suspension with PST polygraphite bushings and sway bars, R/T torsen bars and R/T leaf springs (swaped from the R/T project car.) I would like to get 20+ MPG, and these Coronets are pretty roomy and have large trunks making them a nice ride for long drives.

The car is also an A/C car with power steering and power brakes. and it also was originally a bucket seat center console car. I would like to install a new radio/CD player and maybe cruse control, but that can wait till the car is put back together.