392 Hemi

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Truckedup
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392 Hemi

Post by Truckedup »

I get on the HAMB hot rod site frm time to time ..Many guys there go on and on how the first generation Hemi is so powerful...How much power can a 392 make on pump gas and be a tolerable street engine?
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Re: 392 Hemi

Post by In-Tech »

How much money you got? :mrgreen:
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: 392 Hemi

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In-Tech wrote: Sun Jul 18, 2021 7:39 pm How much money you got? :mrgreen:
10 grand
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Re: 392 Hemi

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Not enough, lol. Supercharged(screw)/Intercooled IAT under 130f you can make 2:1 hp per cu in Hemi, 87 octane
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Re: 392 Hemi

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I'm interested in N/A, one or two four barrel carbs,a hot rod engine. cam, headers, good valve work,etc.
...I'm thinking 450 hp from a well tuned first generation street engine
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Re: 392 Hemi

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Not a problem with a good intake and exhaust, keep the stepped exhaust, small to big. 1.5 to hp/cid fairly easy with good planning. The hemi chamber is very forgiving to octane. Cam events are critical too especially rpm and exhaust tract.
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: 392 Hemi

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In-Tech wrote: Mon Jul 19, 2021 1:00 am Not a problem with a good intake and exhaust, keep the stepped exhaust, small to big. 1.5 to hp/cid fairly easy with good planning. The hemi chamber is very forgiving to octane. Cam events are critical too especially rpm and exhaust tract.

Most if not all older bikes have true hemi chambers...They are not forgiving to octane and detonation can be a problem on pump gas even on stock engines...Yes they are air cooled ...
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Re: 392 Hemi

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Truckedup wrote: Mon Jul 19, 2021 6:19 am
In-Tech wrote: Mon Jul 19, 2021 1:00 am Not a problem with a good intake and exhaust, keep the stepped exhaust, small to big. 1.5 to hp/cid fairly easy with good planning. The hemi chamber is very forgiving to octane. Cam events are critical too especially rpm and exhaust tract.

Most if not all older bikes have true hemi chambers...They are not forgiving to octane and detonation can be a problem on pump gas even on stock engines...Yes they are air cooled ...
They are very forgiving to octane, what they are not forgiving to is preignition. Bro, I know you know what you're doing. 2tc toyota in the early 90's and many 1000's of hours on the dyno is how I was playing. There is no way to scavenge the cross flow hemi chamber, so all you have left is to control the combustion of said leftovers.
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: 392 Hemi

Post by PackardV8 »

Truckedup wrote: Sun Jul 18, 2021 5:24 pm I get on the HAMB hot rod site frm time to time ..Many guys there go on and on how the first generation Hemi is so powerful...How much power can a 392 make on pump gas and be a tolerable street engine?
Even though your hemi experience is air cooled, you probably know as much about potentials as most HAMBurgers.

There's a lot of real world experience on any obsolete engine on the H.A.M.B.; sifting it out is the challenge. The guys-who-know get buried among the dozens of wannabee replies to any thread and the dozens of threads per hour.

In my limited experience years ago, street-drivable-normally-aspirated hemi power peaks early. As you know from your Triumphs, as compression goes up, the combustion chamber shape goes large-area-squished pancake and the piston dome gets in the way of breathing and spark. Flattops down in the hole were one reason the early hemi ruled blown fuel. Once the NHRA banned fuel, the SBC was all over the early hemi.
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Re: 392 Hemi

Post by In-Tech »

Yes, the dome used in a hemi chamber is a bad thing, flat dome always makes more power even with less compression, regardless of cam timing. This was 18:1
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Re: 392 Hemi

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In case anyone is wondering about the cut pipe in a couple pictures, that's what I found in the backyard to make my tapered sleeve and ring squaring tool out of. :mrgreen:
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: 392 Hemi

Post by PackardV8 »

Truckedup wrote: Sun Jul 18, 2021 11:41 pm I'm interested in N/A, one or two four barrel carbs,a hot rod engine. cam, headers, good valve work,etc.
...I'm thinking 450 hp from a well tuned first generation street engine
What is the application? A '57-'58hothemiheads.com392" weighs about 765# and is wiiide. The Hot Heads guys have a lot of good aluminum heads, intakes, water manifold, et al, to get the weight down, but it's an expensive build. The other problem is finding a good core is almost impossible. I haven't seen one in years.
hothemiheads.com
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Re: 392 Hemi

Post by Truckedup »

PackardV8 wrote: Mon Jul 19, 2021 4:08 pm
Truckedup wrote: Sun Jul 18, 2021 11:41 pm I'm interested in N/A, one or two four barrel carbs,a hot rod engine. cam, headers, good valve work,etc.
...I'm thinking 450 hp from a well tuned first generation street engine
What is the application? A '57-'58hothemiheads.com392" weighs about 765# and is wiiide. The Hot Heads guys have a lot of good aluminum heads, intakes, water manifold, et al, to get the weight down, but it's an expensive build. The other problem is finding a good core is almost impossible. I haven't seen one in years.
hothemiheads.com
Jack, it's just a idea right now....I can see 10 grand won't go very far...
InTech, pistons I use in the race bikes, 10.5 compression, flatter top , a narrow squish band around the piston about .032 clearance. On street bikes about 9.2 compression, 100 degree intake lobe center, runs ok on 91 octane You can see the squish band in the photo
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Re: 392 Hemi

Post by In-Tech »

Hiya trucked, I've been out of the toyota game for a while. I talked with Mike about doing some tight lobe center stuff but there just aren't any UGL cores around anymore. It was fun to play with :)
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl
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