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Max cubic inch out of a 401

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Hurst390 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Nov/28/2021 at 7:38am
Originally posted by amxblair amxblair wrote:

Any chance of re-posting those pictures of FBS 500" AMC iron block?
SC/Hurst Rambler

11.62 120

100% Street Legal
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Nov/29/2021 at 5:35pm
Originally posted by DragRacingSpirit DragRacingSpirit wrote:

I actually have a crank in the works from Moldex for a 4.15" stroke but wanted to hear your thoughts on it. I just thought that 4.25" was to tight.

But I would still love to see some of your calculations

I am planning on spinning it to 8-8500 and N/A If I have the flow I need to make horsepower at that rpm level.

Indy block, moldex billet crank and GRP 6.2"rods is the bottom end that I have in the works along with the 300cc version of the -1 heads.

I have a min csa of about 3.65 sq in for the Indy CNC 300, and with the head high velocity limit (Race Engine) I get 8493 rpm for 4.375/4.150 B/S. That is pretty aggressive, and maybe a touch too aggressive for an Indy head. What it means is 8000 rpm is probably pretty good, and for sure the head is not too big. More rpm or inches is pushing it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DragRacingSpirit Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2021 at 1:08pm
ok....thank you for your input on this issue. I understand what you are saying.

There 300cc head is just not big enough to spin a 4.15x4.375 to more than 8000 rpm.

So that comes down to the issue what is the best approach......spin 499 inches to 8k or use less stroke for smaller cubes and spin higher. But will that really improve the maximum horsepower potential?

To bad that they don't offer a 325cc and 345cc heads like they do for their BB Mopar 440-1 head.

Is there any improvement that can be done to their 300 cc head to enlarge the ports for for more port volume. To stay with a wedge design head we need a newer updated copy of a brewer head or a hair dryer/blower.

I really want to see what I can get it to run n/a.


Edited by DragRacingSpirit - Nov/30/2021 at 1:12pm
Best 1/4 mile 8.99, 1/8 mile 5.71, 60 foot 1.27, no power adders
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2021 at 1:59pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2021 at 2:08pm
I think the Indy head is really quite good for what it is, meaning a true wedge with sorta stock configuration. The efficiency or flow/sq in is really quite good, again for a wedge. I've never had a chance to really study the Brewer (would love to) so I can't comment much, but there cannot be much in it over an Indy. You're still stuck with the inherent wedge/valve size limitation with the bore. I've had a bit of involvement with the B1 Mopar which may be closer to the Brewer, and it was a bit better efficiency and more CSA.

I don't think there is much left in the Indy - there is not much material left and it's pretty good as is. With a free hand you can get a little higher port and better angle than the 300, but it's a LOT of work for not much gain. And you probably will be welding up the leaks.

If you really want an improvement you gotta go to canted. But that's a whole new game.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2021 at 2:18pm
BTW I would have to get those Brewers on my machine to believe that flow number. It's a little hard to stomach in efficiency. I said the exact same thing on the B1 and some other high end wedge stuff including some of the latest and greatest LS stuff. When the flow sheet shows above 100% efficiency it's pretty hard to stomach, and never once has the head matched one of those magical flow sheets.

But not hard to believe that the head is a really topnotch piece. Just everyone wants the big flow number, and some machines do that.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2021 at 3:36pm
But Ken, with exchange they are only $10,225 for the pair! There also aluminum so shipping would be a bargain. 
Now the brokerage fees and taxes are the big ticket. You can pay twice the purchase price.
I'll look for some in Alberta as they will be cheaper.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DragRacingSpirit Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2021 at 4:12pm

I have saw those on racing junk before. I have heard a lot of different things about the Brewer heads from differing posts on the internet. Those pair of heads on Racing Junk are in Missouri and not that far away from me.

It would be nice if they could be studied and evaluated but I would rather spend my money on new and known than an unknown risk.


Edited by DragRacingSpirit - Nov/30/2021 at 4:19pm
Best 1/4 mile 8.99, 1/8 mile 5.71, 60 foot 1.27, no power adders
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2021 at 4:30pm
There is a gentleman near me that has modified BB Mopar Indy heads and intake on his 390.
He does mid 11's with his 73 AMC station wagon. This is a 4000+ lb car, custom 9" rear.
Don't know who did the heads, but Ken would likely know him as he races at the same track.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2021 at 5:21pm
Bigger HP numbers are usually reached at higher rpm, but torque starts falling off before the highest hp is hit. So a larger cube engine running under 8K rpm is still likely to build as much (or more) usable power as a higher rpm smaller engine turning 8K +.  High rpm/hp numbers are mainly bragging rights, but with the right combination of trans, gearing, and chassis you can make it work on an all out drag car. Not streetable though...
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