Re: Chapman Stage VI port CSA?
[Re: Mjollnir]
#170521
12/19/08 12:50 PM
12/19/08 12:50 PM
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Posts: 9,924 Weddington, N.C.
Streetwize
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I have a set of 285's on my 517, with 12:1 comprssion there's plenty of port velocity (very broad torque all over even with a big roller cam). I didn't measure the port x section all the way through but I saw no pinchpoints and the tall roof combined with a short turn is one of the nicest I've seen on any Mopar BB wedge.
The Chapmans are noted for being the most efficient of the MW heads (i.e., cfm per CC of port....380cfm is typically reserved for heads in the 325+ cc volume range but also you need to factor in that head (Like the indy) have the B/RB 'spacer' factored into the casting, tough to do a true Apples to Apples.....all I can say is the flow is outstanding
Last edited by Streetwize; 12/19/08 12:51 PM.
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Re: Chapman Stage VI port CSA?
[Re: Mjollnir]
#170524
12/19/08 08:42 PM
12/19/08 08:42 PM
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moparniac
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how does chapman get those heads to flow so well....
Mopar Performance
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Re: Chapman Stage VI port CSA?
[Re: Mjollnir]
#170525
12/19/08 08:44 PM
12/19/08 08:44 PM
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Joined: Oct 2003
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Von
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Quote:
Thank you gentlemen. I have an opportunity to buy a set of Chapmans for about what a set of CNC'd Indy heads would run me;.
Hope they arent the set for sale in Quebec.
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: Chapman Stage VI port CSA?
[Re: Von]
#170527
12/19/08 08:57 PM
12/19/08 08:57 PM
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Mjollnir
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Quote:
Hope they arent the set for sale in Quebec.
No, they're local.
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Re: Chapman Stage VI port CSA?
[Re: Mjollnir]
#170528
12/19/08 09:29 PM
12/19/08 09:29 PM
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Streetwize
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Jeff, yeah that's what I was saying. Actually the increase of cc's (compared to an Indy) calculates to ~28CC's apples to apples based on area (~1/2" width per side x 2.6 x 1.3)^16.387 = 27.7cc + 285 = 312.7....roughly the size of the Indy-1 which is around 310 IIRC The mid-lifts are what owns on the chapmans....286 @.400 and 362 by only .600 means if you want easy 700hp potential even a mild lift easy on the springs street roller can get it done. Plus they also have a killer exhaust port compared to the VICs and EZ's. If you want stock block cracking power go up to .700 to tap another 20cfm and go for an all out racing powerband. On 512 inches go with the 285's....worth it for the bigger 2.25 valve alone on the big stroke motors. If you can get them at a good price they're tough to beat.
Last edited by Streetwize; 12/19/08 09:36 PM.
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Re: Chapman Stage VI port CSA?
[Re: moderncylinder]
#170529
12/19/08 10:05 PM
12/19/08 10:05 PM
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Mjollnir
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Quote:
the port on an indy head is longer making it hold about 40-45 cc's more than std,, putting your 285cc chapman heads at about a 325-330 indy head.
jeff
That's always been the problem when trying to compare ports based solely on runner volume - it doesn't take into account the length of the runners, which can differ substantially between two heads. CSA is somewhat more accurate as a comparison tool, but still doesn't give any indication of flow quality, swirl and tumble, etc. I just wanted to make sure that I didn't under-port the engine and choke its potential, or over-port it and lose throttle response.
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Re: Chapman Stage VI port CSA?
[Re: Von]
#170530
12/19/08 10:14 PM
12/19/08 10:14 PM
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Joined: Jul 2006
Posts: 686 toronto
6PAK70CUDA
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Quote:
Quote:
Thank you gentlemen. I have an opportunity to buy a set of Chapmans for about what a set of CNC'd Indy heads would run me;.
Hope they arent the set for sale in Quebec.
Funny you should say that...I noticed they have been for sale for a very,very long time. What's the deal?
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Re: Chapman Stage VI port CSA?
[Re: Streetwize]
#170533
12/20/08 12:06 PM
12/20/08 12:06 PM
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Joined: Oct 2004
Posts: 1,752 detroit area
moderncylinder
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yeah,, i was thinking it was 3/4 inch longer, maybe i had the victor head in my mind or something,, i make a max wedge 2.700x1.400 so like you said about 30 cc's
i just did another set of 440-1 heads using a 2.250 valve on a 4.380 bore using indy's cnc casting which has a very small port in it so you can do what you want, at .400 they flowed 292, at .600 they flowed 359, 375 at .700 and 381 at .800.. the exh flowed 211 at .400, 242 at .500, 263 at .600, 279 at .700, 291 at .800,, 311 with a tube on it at .800.
im sure the chapman head has a little better throttle response, the port is raised up some if i remember right,, having to use a rb manifold on a b engine,, at 2500rpm it might have better throttle response but up at 4000 or so im sure it doesnt matter too much compared to an indy head, once you put a 4.15 or bigger stroke in it. ill bet that you build two engines comparably and the difference in torque curves wont be more than a few % different from the chapman to the indy.
with chrysler stroker motors the base thought of having a 200 cc intake runner like a stock head goes out the window. a 300 cc port is not huge for a 4.15 or 4.25 stroke,, for drag racing,, not pulling out tree stumps
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Re: Chapman Stage VI port CSA?
[Re: Streetwize]
#170534
12/22/08 11:14 AM
12/22/08 11:14 AM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Quote:
If you can get them at a good price they're tough to beat.
What did you end up doing for rockers, etc.? Don't they require some special rocker pedestals and offset intakes?
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Re: Chapman Stage VI port CSA?
[Re: BradH]
#170536
12/22/08 12:28 PM
12/22/08 12:28 PM
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Joined: Jan 2003
Posts: 9,924 Weddington, N.C.
Streetwize
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Brad,
It was really no big deal.
Wound up using 1pc Race W-2 style 'Billet block' type pedestals and used the 1.6 Hughes Victor intake rockers....took a bit of relieving around the intake port walls to clear the pushrods for my low deck roller cam combo....for a flat tappet RB it would probably cleared without any real work. Rocker geometry worked out really nice.
But the really astounding thing about the 285's is the Chapman CNC work, the beautiful (uniform throughout) port shape and the Flawless Zeus Castings themselves....head and shoulders over anything mopar ever produced before.
Last edited by Streetwize; 12/22/08 12:34 PM.
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Re: Chapman Stage VI port CSA?
[Re: moderncylinder]
#170538
12/23/08 10:00 AM
12/23/08 10:00 AM
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Mjollnir
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Quote:
i just did another set of 440-1 heads using a 2.250 valve on a 4.380 bore using indy's cnc casting which has a very small port in it so you can do what you want, at .400 they flowed 292, at .600 they flowed 359, 375 at .700 and 381 at .800.. the exh flowed 211 at .400, 242 at .500, 263 at .600, 279 at .700, 291 at .800,, 311 with a tube on it at .800.
Those are some stout flow numbers.
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Re: Chapman Stage VI port CSA?
[Re: CALSDART]
#170539
12/23/08 10:07 AM
12/23/08 10:07 AM
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Mjollnir
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Quote:
What is the price of the Chapmans
The list price for the 285cc version, P4876386, is $2665 - each. I Googled the P/N real quick and found a place that has them for $2199 apiece.
As many people before have said, these heads would undoubtedly be more popular if they were priced more in line with competitive offerings from Indy and Edelbrock.
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