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Re: HP per cubes...
[Re: Jeepmon]
#1772125
03/05/15 01:57 PM
03/05/15 01:57 PM
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Joined: Jan 2003
Posts: 19,372
Las Vegas
Al_Alguire
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 19,372
Las Vegas
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Hp per cube is directly related to $$$$ per cube. The bigger the engine the more difficult/costly HP per cube is. Cylinder heads play a large role here the "weaker" the head the less HP you will make plain and simple. For instance a TRUE 900HP Indy -1 head is almost at unicorn status. There are MANY variables, rotating weight, RPM, head flow, port design, intake design, cam profile, block material, compression, header size design, collector size and design, type of fuel used, etc etc etc but if it aint got the heads it aint gonna happen. Some folks are never satisfied  Most people would be thrilled with close to 4 digit HP for $20K in what should be a reliable, low RPM, non spring eating, reliable engine in a Mopar, some not so much  One last tidbit. HP from a dyno is just a number. If you cannot put it in a chassis with the proper combination of pieces and make it work all the power in the world is NEVER gonna turn into quick ET's But what do I know.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: HP per cubes...
[Re: Jeepmon]
#1772127
03/05/15 02:06 PM
03/05/15 02:06 PM
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Joined: Jan 2003
Posts: 19,372
Las Vegas
Al_Alguire
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 19,372
Las Vegas
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AS I think I said already the bigger they get the harder it is to get the HP per cube higher.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: HP per cubes...
[Re: Jeepmon]
#1772128
03/05/15 02:13 PM
03/05/15 02:13 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Ok Al... lets take that $20k number and expand on it.. If you're building a little 410 stroker.. what would you be happy with horsepower wise.. and then graduate that to a big block 500"
One thing that comes into play is the block... if you
run a stock block your not gonna try to get the BIG
HP numbers.. it just wont last.. my 416 only makes
1.48 HP per cu.. I can/could go a bit higher but its
a N/A street engine.. plus it makes more power than
I can really use for the track being I can only run
10.0 now days
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Re: HP per cubes...
[Re: Jeepmon]
#1772131
03/05/15 03:32 PM
03/05/15 03:32 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Mike.. your situation really doesnt apply as you had a specific horsepower limit mind.. which it sounds like you met..
In my case, my (street/pump gas) small block makes 1.2x per cube... which I'm not real happy with, but have accepted since it is a street car.. The big block race motor is making 1.6x-ish per cube..
It seems everytime I sit down with an engine builder, the one stat they keep throwing out is HP vs Inches.. So I was just wondering what everyone thinks is a suitable number
On my BB 514ci I was shooting for 1.9+ hp per cu
but I ended up selling all that.. that was with B1m/c
heads and I was gonna spin it to 9000... on paper
it would have made it.. but you know how that works
out.. that was running big lift and 15:1 and light
rotating assembly stuff
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Re: HP per cubes...
[Re: Al_Alguire]
#1772132
03/05/15 05:20 PM
03/05/15 05:20 PM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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Quote:
AS I think I said already the bigger they get the harder it is to get the HP per cube higher.
From what I have seen and read that is so true. I completely agree. Course it depends on the eng also as if its a race car eng or a street car eng. Myself I was shooting for about 600 hp with a 440 but decided it was easier and cheaper to put the 4.15 crank in it to shoot for about 600 hp with 493 cubes but I knew it was a 10.6 comp street eng that would run on pump through a full exh. I would kinda look at it more like hp per weight of the eng where a 440 would weigh the same as a 493 or 542 so even if you have more cubes the eng still weighs the same if its a 440 or 542 or whatever. Course I understand the more hp per cube the more satisfied you are with your build. Myself I knew I did not have the money to ever even think of competing with the big boys so I try to make the best of what I have and then consider what the eng is built for. But 1.5 hp per cube is not bad at all as thats 615 hp from 410 cubes and thats not bad for an average race eng. Ron
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Re: HP per cubes...
[Re: AndyF]
#1772135
03/05/15 06:19 PM
03/05/15 06:19 PM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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I pretty much build hot street engines because there is no tracks around and don't get too caught up in HP per cube, you can run shorter strokes and artificially get higher HP/Cube. Customers get the biggest smile out of TQ so I build to make power through efficency and stroke just about every engine if I can talk them into it, NEVER had a customer say they wasted money on a stroker even though it would show less power per cube over a equal but shorter stroke engine. I figure if you are going over 1.25 per cube on a street engine you are going to have to turn too many RPM to reach the power band. Customers are a lot happier if they are not trying to deal with too rough idle, too high RPM idle, high stall converters, real low gears, shifting so high you feel like it's gonna blow, exhaust fumes trying to gag them at every light, worrying about noise police... I get an ocasional outlier that wants to rev the pee out of it (366 W2 I am building/fighting right now) but for me 1.25 or so seems to really be the sweet spot to keep a customer real happy. I am building a 410 right now for myself and with EFI hoping I can tolerate it around 1.45, if I can't stand it I will throw more cubes under it 
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: HP per cubes...
[Re: HotRodDave]
#1772136
03/05/15 06:35 PM
03/05/15 06:35 PM
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Joined: Jan 2003
Posts: 7,494
Minnesota
Hemi_Joel
master
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master
Joined: Jan 2003
Posts: 7,494
Minnesota
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The first thing that pops into my head, is that unless you are racing in one of the rare heads up classes that regulates engine CID, hp per cube is irrelevent. More important is HP per dollar, including cost of build, operating cost, and (sometimes)potential resale; all within the parameters of satisfying the owners personal tastes and preferences, and meeting the owners performance goals on the track.
[img]http://i.imgur.com/boeexFms.jpg[/img]31 Plymouth Coupe, 392 Hemi, T56 magnum RS23J71 RS27J77 RP23J71 RO23J71 WM21J8A I don't regret the things I've done. I only regret the things I didn't do. "Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
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Re: HP per cubes...
[Re: Jeepmon]
#1772137
03/05/15 06:37 PM
03/05/15 06:37 PM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
master
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master
Joined: Nov 2004
Posts: 6,890
North Alabama
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Quote:
If you're building a n/a race motor.. what horsepower per cubic inch would you be happy with?
Me personally, I think 1.5 per cube is a dissapointment... while 2.0 per cube is do-able.. if you have a big enough checkbook... So I was just wondering... at what point would you pat yourself on the back and say "job well done" ??
Disclaimer: I know there are a lot of variable.. such as expectations... reliability.. repeatability, components and etc.. so for the sake of this discussion... lets say its the average of the average race motor build..
This is too much of an open ended question, because as Al said, it all boils down to how much you are willing to spend, how good your heads are and what your goals are.
As already mentioned, if your goal is 2.0hp per inch with a 500" motor and Indy or lesser heads, you are gonna be disappointed. Replace those heads with nice B-1s, the goal is more easily achieved. On your 410" smallblock deal, 820 is doable, but you need a REALLY good head. BUT, 410 inches is a waste, if the head you choose won't flow the air to support those inches
I did a 520" BB a few years ago with a really nice set of Barton ported 440-1s. Now this was a nitrous motor, so had heavy pistons, not a ton of compression, plus I was limited on the cam, because of valve length. It made 850 I think, which would come in a tick under 1.65 per cube. I was happy with that, given the parts and intended purpose of the motor. Now, given the heads I had, even if you raised the compression to the moon, put a monster shaft in and turned it out of the frame, I still doubt it would have cracked 900hp. The airflow just wasn't there. So all that extra money spent, PLUS making the motor less reliable, to only gain a few hp, would have been a very poor investment. Not about inches either. Stretch THIS motor to 600" and still won't make 900. Again, it is about goals and the parts in hand, as to what a good number vs dollars spent is.
Now, at the same time I did the BB Mopar, I also did a 434 Chevy, with one of the best 18* heads you can buy. Also a nitrous motor and it made 842.........thats 1.95hp per inch, which sounds great, but this is what a killer 18* head on a small block SHOULD make.
The two above comparisons, show that it is ALL about airflow, because the killer 18* small block heads, moved about the same air as the fully ported 440-1s and even though the big block was roughly 100" bigger, the HP was essentially the same
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Re: HP per cubes...
[Re: Monte_Smith]
#1772138
03/05/15 07:06 PM
03/05/15 07:06 PM
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Joined: Oct 2009
Posts: 1,267
North, Alabama
D-50
pro stock
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pro stock
Joined: Oct 2009
Posts: 1,267
North, Alabama
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My small block motor is a older Engine Masters motor that Brett Miller was involved with and it is a pump gas motor. It made 662 hp @ 7300 and it is 394 ci, and 10.9-1 comp.. That comes out to 1.68 hp per ci.It had a 1050 on it and better headers than it does now. My best time in my sig. is with a stock fuel system, a old 950 untuned Holley and headers I built myself with mufflers. The Wallace racing calculator says I am making around 625 hp. I upgraded the fuel system and put the 1050 on it now and hope it goes quicker if it will hook now. Maybe I will find out in a few days.
Last edited by D-50; 03/05/15 07:07 PM.
1.33 60 ft,6.21 at 110.59 in the 1/8, pump gas small block,2950lbs,drag radials,mufflers and driven to track ...
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Re: HP per cubes...
[Re: quickd100]
#1772140
03/05/15 08:43 PM
03/05/15 08:43 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
My truck motor makes 1.41 hp per cubic inch. It's reliable, runs on 89.5 pump swill, but is severely head limited. It's a 99.9% street motor with a few passes down the track. A better set of heads and some compression, and a bit more cam I'm pretty sure 1000hp would be close to my reach. Dave
Thats the same with my SB.. the heads are good but
its 10.4:1 and runs on 87 octane.. but when I go to
the track I'll put 93 in it... its all I really wanted
and it runs on moose piss... that part make me happy..
hell I could have upped the compression and ran it
on E-85 but I built it for drag week and in a lot
of places you cant get E-85.. so it is what it is
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Re: HP per cubes...
[Re: D-50]
#1772141
03/05/15 08:48 PM
03/05/15 08:48 PM
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Joined: Jun 2004
Posts: 6,780
Alabama
Mopar-Al
master
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master
Joined: Jun 2004
Posts: 6,780
Alabama
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I don't know what this 572 B1 ebgine I just built will show as HP until the track opens in the next week or 2. But it is a 14.5 comp big cam engine with a 1250 and big 2 3/8ths headers. I have the timing dialed back on the trigger to 34 right now for break in, but i'm hoping for a good number. It may take a few times to get the tune in, but I have the patience to wait.
This was my first attempt in building an all aluminum engine, and I learn as I go. I expect closer to a maybe 1.7 ratio the next season. Which may yield around 970 or so hp. When your alone, the experience takes a bit more time by trial and error. As of now, I have no Idea of the hp range this engine is, so I am not going to comment. I will say, name brand parts will attack a wallet, very quick. I spent a lot of money this last 5 months getting ready. You have to crawl before you walk, if you don't pay the pro for what they build and know.
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With a decent set of Indy 360 or 360-2 heads and more C.I. and compression I can't see why 1.6+ HP per C.I. isn't doable on race gas
That made that motor miss above 5200 RPM 
I just don't know that combination yet 
I'm still working on it though 
