421 cube pulling truck engine

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JoePorting
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Re: 421 cube pulling truck engine

Post by JoePorting » Sat Jan 27, 2018 6:29 pm

Sounds like a nice engine build except for the heads. I'd think the heads would limit the power to around 600 hp. If you want 750 hp, you'd have to upgrade to a head with a 2.20" intake valve like in a Brodix 18C head or a Dart 9 degree head. My experience with welding up the pushrod pinch area is that it's a waste of time. The bottle neck is the small intake valve and the shallow intake bowl. If the rules demand an iron head, then I guess there's not too many good options.

One idea is to change the valve sizes from 2.08/1.6 to 2.20/1.5 if the larger intake will fit the head gasket (valve spacing issues). Or maybe 2.15/1.55 is another option. But even then power will only improve by 20/30 hp at best.
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Re: 421 cube pulling truck engine

Post by randy331 » Sat Jan 27, 2018 7:34 pm

JoePorting wrote:
Sat Jan 27, 2018 6:29 pm
Sounds like a nice engine build except for the heads. I'd think the heads would limit the power to around 600 hp.
That would be very disappointing to go to all this expense and work adding cubes, compression, etc, only to loose 30 HP over the 355 that was in it last year.

JoePorting wrote:
Sat Jan 27, 2018 6:29 pm
One idea is to change the valve sizes from 2.08/1.6 to 2.20/1.5 if the larger intake will fit the head gasket (valve spacing issues). Or maybe 2.15/1.55 is another option. But even then power will only improve by 20/30 hp at best.
Since the 355 only had a 2.05" valve, and this set of heads have 2.08" valve, is it at least possible this engine won't loose power over the 355 ?

Randy

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Re: 421 cube pulling truck engine

Post by Keith Morganstein » Sun Jan 28, 2018 5:02 am

randy331 wrote:
Sat Jan 27, 2018 7:34 pm
JoePorting wrote:
Sat Jan 27, 2018 6:29 pm
Sounds like a nice engine build except for the heads. I'd think the heads would limit the power to around 600 hp.
That would be very disappointing to go to all this expense and work adding cubes, compression, etc, only to loose 30 HP over the 355 that was in it last year.

JoePorting wrote:
Sat Jan 27, 2018 6:29 pm
One idea is to change the valve sizes from 2.08/1.6 to 2.20/1.5 if the larger intake will fit the head gasket (valve spacing issues). Or maybe 2.15/1.55 is another option. But even then power will only improve by 20/30 hp at best.
Since the 355 only had a 2.05" valve, and this set of heads have 2.08" valve, is it at least possible this engine won't loose power over the 355 ?

Randy
Surely more than 600 HP can be made with a 2.08" valve. 2.6" CSA, 240 CFM port.
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Re: 421 cube pulling truck engine

Post by randy331 » Sun Jan 28, 2018 11:17 am

Keith Morganstein wrote:
Sun Jan 28, 2018 5:02 am
Surely more than 600 HP can be made with a 2.08" valve. 2.6" CSA, 240 CFM port.
The heads for the 421 are in the 315-317 cfm range, so it will need to make 2.38 HP/cfm to meet my 750 HP goal. That's doable.

With 2.6 in csa it will need to make 750/2.6 = 288 HP per inch of csa. That's doable.

If I can make 1.45 pounds of TQ/cubes at 5800 ish rpm that will be 610 TQ. And hold on to %90 of that TQ till 7200 that will be 753 HP.
My calcs for port size/csa puts the 5800 rpm and 7200 rpm for peak tq and peak HP right in line with past results, and 1.45 pounds/cubes is certainly within reason for a build like this on Q16 fuel. Our emc 353 made 1.44 LBs/cube under much more limited rules.

Other calcs seem within reason to make 750 HP out of this build.

1.78 HP/cube don't seem out of line for this type of build.

But,.. maybe all that counts is intake valve size ? :?: :D

Randy

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Re: 421 cube pulling truck engine

Post by RevTheory » Sun Jan 28, 2018 11:56 am

If you're willing to share, what are you doing to calculate your target peak torque rpm?

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Re: 421 cube pulling truck engine

Post by Keith Morganstein » Sun Jan 28, 2018 12:09 pm

randy331 wrote:
Sun Jan 28, 2018 11:17 am
Keith Morganstein wrote:
Sun Jan 28, 2018 5:02 am
Surely more than 600 HP can be made with a 2.08" valve. 2.6" CSA, 240 CFM port.
The heads for the 421 are in the 315-317 cfm range, so it will need to make 2.38 HP/cfm to meet my 750 HP goal. That's doable.

With 2.6 in csa it will need to make 750/2.6 = 288 HP per inch of csa. That's doable.

Randy
Typo, I meant to write 240 CC port, (not 240 CFM)

And yes I think your goals are achievable.
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Re: 421 cube pulling truck engine

Post by CGT » Mon Jan 29, 2018 10:21 am

randy331 wrote:
Sun Jan 28, 2018 11:17 am
With 2.6 in csa it will need to make 750/2.6 = 288 HP per inch of csa. That's doable
randy331 wrote:
Sun Jan 28, 2018 11:17 am
so it will need to make 2.38 HP/cfm to meet my 750 HP goal. That's doable.
Considering that particular set of heads prior to your new recent rework made over 2hp per cfm(290 cfm) on a 10.5:1 357 with a hyd roller. I think its very doable.
"Your just doing your own work which is great but nothing new as there's plenty of people who've done the same basic things in building "

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Re: 421 cube pulling truck engine

Post by steve316 » Mon Jan 29, 2018 3:36 pm

On this type of build I think your are being conservative on your estimates.I think your torque will be in the 1.5 to 1.52 range; and HP in the 1.85 to 1.9 range. The spread between peak tq & peak hp will depend on min csa and max csa in the intake track. JMO; looks good to me =D>

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Re: 421 cube pulling truck engine

Post by user-17438 » Mon Jan 29, 2018 9:26 pm

JoePorting wrote:
Sat Jan 27, 2018 6:29 pm
Sounds like a nice engine build except for the heads. I'd think the heads would limit the power to around 600 hp. If you want 750 hp, you'd have to upgrade to a head with a 2.20" intake valve like in a Brodix 18C head or a Dart 9 degree head. My experience with welding up the pushrod pinch area is that it's a waste of time. The bottle neck is the small intake valve and the shallow intake bowl. If the rules demand an iron head, then I guess there's not too many good options.

One idea is to change the valve sizes from 2.08/1.6 to 2.20/1.5 if the larger intake will fit the head gasket (valve spacing issues). Or maybe 2.15/1.55 is another option. But even then power will only improve by 20/30 hp at best.
Lol.. a 2.200 valve can move over 450cfm of air. I think the 2.080 is small as I would prefer a 2.100. But not a 2.200. You couldnt get the port large enough to require that big of a valve. Nor the combustion chamber shape, approach from the short turn. Etc. There is more to making hp than throwing the biggest valve in it and the most cfm.

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Re: 421 cube pulling truck engine

Post by randy331 » Wed Jan 31, 2018 1:08 pm

MTENGINES wrote:
Mon Jan 29, 2018 9:26 pm
But not a 2.200. You couldnt get the port large enough to require that big of a valve.
So you don't go along with the put the largest valve that will fit in every head theory ?
You seem to imply that the valve should be sized according to port CSA, and I think so too.
MTENGINES wrote:
Mon Jan 29, 2018 9:26 pm
There is more to making hp than throwing the biggest valve in it and the most cfm.
Not to some.

Randy

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Re: 421 cube pulling truck engine

Post by proheader » Thu Feb 01, 2018 6:25 am

IMAG0249.jpg
Plenty of 4-2-1 headers in Missouri..
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Re: 421 cube pulling truck engine

Post by In-Tech » Thu Feb 01, 2018 6:28 am

I really like the headers, not so sure on that dropped valve though. :shock: [-o< :mrgreen: And where is the o2 bung? :wink:
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: 421 cube pulling truck engine

Post by proheader » Thu Feb 01, 2018 1:53 pm

O2 bung is down on the inside of the collector... 74-92 squarebody fenderwell headers

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Re: 421 cube pulling truck engine

Post by Keith Morganstein » Sun Feb 04, 2018 10:46 am

proheader wrote:
Thu Feb 01, 2018 6:25 am
IMAG0249.jpg

Plenty of 4-2-1 headers in Missouri..
Now I have! Missouri is the “show me” state after all!
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Re: 421 cube pulling truck engine

Post by CGT » Tue Feb 06, 2018 11:16 am

Any updates? Head flowz? Short block flowz? Perfect cam flowz? :?
"Your just doing your own work which is great but nothing new as there's plenty of people who've done the same basic things in building "

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