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Must utilize a stock bore spacing 400 Block

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Can be done. 426 guys make 900 -1000 with stock heads. Are Preddys better than S/S hemi heads?

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Must utilize a stock bore spacing 400 Block

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Guys - I dont think an aftermarket block is out of the question. The given parameter is to maintain stock bore SPACING.




As for the question - thats 2.5hp/in, its gonna be tough

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Not enough CI for predator heads IMO. Fully ported B1's and spin it to 9500. Ask Bob Mazzollini, he did it.

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Well it's not that difficult:

Find a "230" casting 400 block
Ported Stage V Hemi head conversion
Big cam .800" lift, 290* @ .050
Twin dominator tunnel ram
15:1 compression ratio
dry sump

edit: forgot to post stock size crank and bore

Throw on some big headers and it dynoed 1008hp at 9500 floating the valves on my Engine analyzer Pro simulator lol

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Well it's not that difficult:

Find a "230" casting 400 block
Ported Stage V Hemi head conversion
Big cam .800" lift, 290* @ .050
Twin dominator tunnel ram
15:1 compression ratio
dry sump

edit: forgot to post stock size crank and bore

Throw on some big headers and it dynoed 1008hp at 9500 floating the valves on my Engine analyzer Pro simulator lol

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Thats some funny stuff right there lol. I do know that it can be done, I just don't if any of the heads available will support it.

Because Larry Pritchett's 390ish ci BBC made well over a 1000HP a year or two ago. But of course, it wouldn't be fun if it wasn't a Mopar

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This is rare air, building a motor like this, at least for me! My guess is toss around the idea of a PSO head,B1TS,or Brewers, testing to find out the minimum bore size for no valve shrouding. Then run more stroke to keep the piston dome size down. Over size roller bearing cam, Pistons, rings etc picked by the best power producer in the engine building world that you can find. Dry sump, high vacuum, every trick you can do to a crank to reduce windage. You will wind up with a rod of almost 7.10 length, rod ratio of 2.25 or so. I don't know how that will affect things, but it will have to be looked at. An after market block may have the deck thickness to reduce the deck height quite a bit. If you are certain you will try using a stock block, then a center counter weighted crank will help.
Basically, I would be looking for an engine builder with experience in high Hp comp classes, or pro stock. They would be able to sort through this stuff and figure out an engine program that will meet the goals.
I don't see a problem making 1000+ hp, just how fat the wallet is. This stuff is real high $$.

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Great thread. Greg nailed it to a tee,, I think one main ingreidiant is the seven one hundred rod to deal with the poor dwell time at rpm and rod angularity... I remember a member on here ,Hutch running a unique 383 combo with VI heads and that rod.

At RPM that S/R ratio wants to rip the pin out of the piston..

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Can be done. 426 guys make 900 -1000 with stock heads.

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Can be done. 426 guys make 900 -1000 with stock heads. Are Preddys better than S/S hemi heads?

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Can be done. 426 guys make 900 -1000 with stock heads. Are Preddys better than S/S hemi heads?

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They're about the same at around 480 cfm. But SS/AH heads need to retain stock valve angles and valve sizes!

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Can be done. 426 guys make 900 -1000 with stock heads. Are Preddys better than S/S hemi heads?

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They're about the same at around 480 cfm. But SS/AH heads need to retain stock valve angles and valve sizes!

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Then there's the small chambered Stage V Millennium Hemi heads that will flow 530

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Fred, do you recall what the 383 hemi P/S guys were making back in the day?

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Back before NHRA had a policy of all Pro Stockers being 500 CI / 2350
pounds, they used to factor different engine at varying
weight-to-cubic inch ratios in that class, assigning whatever figure
they thought would make for competitive racing. Because of heavy
pistons and difficulty in getting the requisite 15:1 compression,
Hemi's had fallen out of favor. Some people tried de-stroking a 426
to 383 cubes, but it didn't work well, exacerbating the compression
ratio problem, as well.

One of my closest friends at that time (1981) was a racer who looked
at the problem and decided to attempt to add the 426 Hemi heads to a
383 block, The 383 was lighter, had a shorter stroke, and a better
rod angle (in his opinion), using shorter, lighter connecting rods.

He eventually built 10 of these blocks, which were 400 CI blocks (he
said the casting cores for the 400's had more meat in the cylinder
walls, determined after sonic testing a bunch of 383/400 specimens.)

One of these blocks ended up in the late John Hagen's Plymouth Arrow
Pro Stocker and without any factory help, nor more than a few months
development time, set the mph record for Pro Stock. The car also was
runner-up to Lee Shepard at the Pomona World Finals that year, the
last race before the 500-inch/2350-pounds for everyone rule went into
effect the following year.

How fast might this combination have been given an ounce of factory
help, or a couple of year's development time???? VERY fast, I'd say.

The modifications to the block were covered in detail in an article I
wrote for Super Stock and Drag Illustrated in the June 1980 issue.
There are lots of photos to document the addition of the row of
hold-down bosses to the valley area, and the machine-work and welding
in of half-tubes to enable the push rods to lay down the required
angle to connect with the exhaust valve rocker arm pushrod sockets.

It was a job for a welder who could weld cast iron to steel and not
have it crack at the seam, due to thermal expansion/contraction.

One of these engines went into an A/Dragster and promptly grabbed the
record for that class (a Canadian, named Wally Dyck.)

Some were sold to high-line Mopar guys like Butch Leal; I think Dick
Landy may have ended up with one. I know that Charlie put a 440
crank in one and ran nitrous to it in a Volare he built for IHRA Pro
Stock.

I also wrote a follow-up article about the accomplishments of that
engine for Chrysler Power magazine a couple of years back, but I
can't remember which issue, offhand.

At any rate, the whole deal was about specific output, and the 383
has it all over the 426 and 440 when it comes to that, because it's
moving a smaller amount of air through the same (Hemi) valves and
ports, enjoying less friction, a shorter stroke, higher redline, and
less reciprocating weight along the way.

Charlie did a lot of research on welding techniques before he came up
with a successful rod and heat combination in order to make welds on
the block that didn't crack in competition, but he finally got it.

I think he was selling these things for a thousand dollars apiece; a
pittance, considering all the work involved.

I think he also added an oil return line from the heads to the pan,
as the Hemi had no oil return that would work with the low-

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Not enough CI for predator heads IMO. Fully ported B1's and spin it to 9500. Ask Bob Mazzollini, he did it.

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No offense to Bob Mazzollini, but he either doesn't run his car hard or he just doesn't make competitive power because when it comes to SS/AS, there's two other mopar guys that own that class that I could look to for help. One is the record holder and the other is the former record holder(Wes Lepold Jr and George Vignogna Jr. Both run SBM around 390's though.

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you cannot use a predator head,, and you cannot use a millenium head or any stage v head for that matter

if you want to run ss/am, or a/sma,, you need to run parts with numbers from mopar

a/sm and ss/am stuff that are fast are small blocks,, but i dont think you can get there with a small block without alot of money,,, the p-5 hemi is dead since there are no "new" available head castings

your best bet is to get a hemi 99 and destroke it some,, run it like that then build a new one with a small bore,, and build a 420 inch motor or so

if youre serious about this i may build one over fall/winter,, i can share ideas with you if you are doing one too

lloyd wofford has a b/sma stratus that has a patterson 358 p-5 hemi in it,, it make 950 or so and runs about .45 under,,, since there are no parts available to build a "better" motor,, there are thoughts to build a hemi 99 around 400 inches for it,, and move to a/sma

jeff

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you cannot use a predator head,, and you cannot use a millenium head or any stage v head for that matter

if you want to run ss/am, or a/sma,, you need to run parts with numbers from mopar

a/sm and ss/am stuff that are fast are small blocks,, but i dont think you can get there with a small block without alot of money,,, the p-5 hemi is dead since there are no "new" available head castings

your best bet is to get a hemi 99 and destroke it some,, run it like that then build a new one with a small bore,, and build a 420 inch motor or so

if youre serious about this i may build one over fall/winter,, i can share ideas with you if you are doing one too

lloyd wofford has a b/sma stratus that has a patterson 358 p-5 hemi in it,, it make 950 or so and runs about .45 under,,, since there are no parts available to build a "better" motor,, there are thoughts to build a hemi 99 around 400 inches for it,, and move to a/sma

jeff

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you cannot use a predator head,, and you cannot use a millenium head or any stage v head for that matter

if you want to run ss/am, or a/sma,, you need to run parts with numbers from mopar

a/sm and ss/am stuff that are fast are small blocks,, but i dont think you can get there with a small block without alot of money,,, the p-5 hemi is dead since there are no "new" available head castings

your best bet is to get a hemi 99 and destroke it some,, run it like that then build a new one with a small bore,, and build a 420 inch motor or so

if youre serious about this i may build one over fall/winter,, i can share ideas with you if you are doing one too

lloyd wofford has a b/sma stratus that has a patterson 358 p-5 hemi in it,, it make 950 or so and runs about .45 under,,, since there are no parts available to build a "better" motor,, there are thoughts to build a hemi 99 around 400 inches for it,, and move to a/sma

jeff

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Jeff, MBE has ads for P-5 stuff on their site. Maybe the castings are from down-under.

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well now you did it, here I was pleased with my w8 s
anyone knows what price range those are in?
I have seen a couple of R4 blocks for sale lately but I don t think you can stuff 400 inches into one of those, maybe there still are R3 blocks available without lifter bores

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If the XR blocks can be had blank, it may be possible to build a nice BIG P-5.

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the mbe heads are the aussy ones, they are very thin around the intake port,, and everyone has issues with them cracking in the bowls,, also the guy from australia doesnt want to sell them to the us anymore cause he is afraid of lawsuits

i dynoed a motor that bes had done and it was down 60hp from what they said,, dyno's are tools

everyone throws around numbers but to run fast in a/sma at about 2900lbs,, 420 inch motor,, 7.80's-7.90's would take about an honest 1000hp at 2000 ft air

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the mbe heads are the aussy ones, they are very thin around the intake port,, and everyone has issues with them cracking in the bowls,, also the guy from australia doesnt want to sell them to the us anymore cause he is afraid of lawsuits

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That is a shame....

After all this time and a completely different supplier, the cracking issues STILL haven't been addressed.

I doubt this would be allowed to happen in the world of SBX and Little Chief heads.

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rick watters has a set of the newer aussie heads and they are sprinklers as well,,,, there is no metal in the bowl area

i was going to have them cast here in the us with no labels or markings, then make plastic pieces which receive in where the labels and markings need to be

it would prob be 5k for a set of castings,, not enough demand,, so started thinking of a small inch 99 hemi

what matters is the timeslip,, not the dyno number,, guys say you loose 2 tenths and some mph going to a 10.5 tire,, i dont believe that if you can still go 1.17 or so 60 ft

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Maybe it s time for Alan to step up and make a billet P5 head , I can test the first pair for free...

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I have had it in the back of my mind but I really don't have the coin for the rest of the engine!
As Jeff also pointed out, the demand would be pretty low and it would really be a labour of love. I don't have a casting lying around to get 3D scanned, and I would really have to work in with someone like Jeff, or MBE or CFE or CFD to get the ports and rocker geometry correct etc. There are four cars in Aussie Pro Stock running P5's currently, plus buyers in the US. I guess the other thing is if they took off I doubt I could keep up with the demand, I do my best work after hours, lol. It's been a dream of mine for sure

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i was thinking of using a 4.440 or a 4.500 bore,, ive done some hemi 99 pro stock before and it didnt seem to mind a smaller bore on the intake air flow,,, if the valve notches were far off the bore to allow a good ring placement,, id run a reasonably small bore to get a 3.25 or 3.30 stroke atleast

the motor i was thinking of building was going to be about 460 inches,, morgan had built one for comp that his son was supposed to race,, which he said he ran it higher and it was down about 65hp from a 500 inch motor,, he ran 6.99 with it at 2350lbs at columbus about 5 years ago in b/a

i could run a 4.500 bore with a typical pro stock crank of 3.625 stroke and get 461 inches,, my car would be about 3200lbs in a/sma,,, id need to make about 1200hp to be real fast,, with it being a wet sump,, you could just get a used pro stock motor and sleeve it down then get new pistons,, though i know from experience that in a motor like that the sleeves will move around alot

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