Hp per cubic inch (N/A vs Blown etc)

[The Hedgehog]

This thought was prompted by a discussion between Eddie Young and myself about building large N/A engines. Although I am not doing anything for a while, I like to fantasize about some cool ideas (like maybe a HUGE N/A). There seems to be a breakpoint in cu inch/Hp where it is better to go with a blown engine as extracting big power from a N/A setup requires HUGE cams and exotic valve trains etc, In hashing out these numbers this is what I found:

1.25 = Nice rule of thumb for reliable setup that is not too costly to build. It would either be solid off the shelf parts for N/A or a well tuned stocker (mag with forged internals) and 5-6 lbs of boost

1.35 - 1.4 = This would be a more aggressive setup. Finely tuned N/A with high flowing heads, bigger cam, high compression and more aggressive tune or a boosted Blue engine.

1.5 - 1.75 = This would be a fairly aggressively tuned boosted engine. It requires a combo of higher boost (7.5-9lbs), high flowing heads, a well selected cam and careful tune.

2.0 = This is big stuff to built by the pros only. Big Boost (think 12-15 lbs), huge heads, big tube exhaust, and very precise tune.

Is this consistent with what others are seeing?

Anyone care to take a stab at the cost breakdowns of these ranges? This should be pretty interesting since there should be a pretty big dispersion between folks like myself that pay for most of their bigger work and Tex that do most of their own stuff. That dispersion should increase as you go up in hp/cu in.

[ITTLFLI]

I was in a Hustler 37 cat over the weekend that had Sterling 753ci N/A motors! Wicked sounding! Took a 116mph pass in it! These motors sounded sweet at 6k!!

[The Hedgehog]

I was in a Hustler 37 cat over the weekend that had Sterling 753ci N/A motors! Wicked sounding! Took a 116mph pass in it! These motors sounded sweet at 6k!!

Wow, that ain't easy to pull off. I have heard about those types of sounds. It is supposed to sound very wicked just like you said. I would love to just hear something like that!

[Pismo]

This thought was prompted by a discussion between Eddie Young and myself about building large N/A engines. Although I am not doing anything for a while, I like to fantasize about some cool ideas (like maybe a HUGE N/A). There seems to be a breakpoint in cu inch/Hp where it is better to go with a blown engine as extracting big power from a N/A setup requires HUGE cams and exotic valve trains etc, In hashing out these numbers this is what I found:
1.25 = Nice rule of thumb for reliable setup that is not too costly to build. It would either be solid off the shelf parts for N/A or a well tuned stocker (mag with forged internals) and 5-6 lbs of boost
1.35 - 1.4 = This would be a more aggressive setup. Finely tuned N/A with high flowing heads, bigger cam, high compression and more aggressive tune or a boosted Blue engine.
1.5 - 1.75 = This would be a fairly aggressively tuned boosted engine. It requires a combo of higher boost (7.5-9lbs), high flowing heads, a well selected cam and careful tune.
2.0 = This is big stuff to built by the pros only. Big Boost (think 12-15 lbs), huge heads, big tube exhaust, and very precise tune.
Is this consistent with what others are seeing?
Anyone care to take a stab at the cost breakdowns of these ranges? This should be pretty interesting since there should be a pretty big dispersion between folks like myself that pay for most of their bigger work and Tex that do most of their own stuff. That dispersion should increase as you go up in hp/cu in.

Long term reliability, meaning hundreds to thousands of hours, is a big difference to consider. 1.25 or less NA and you will get lots of hours. I like the sound of the 753ci..A 598 is easy to build with a standard tall deck. Should easily make 700-750hp and last.

[BigGrizzly]

Pismo No such thing as hundreds of thousand hours, regardless. Now here is the issue, when you get big cubs you will find thaqt 1/2 inch push rods are a necessity. The next thing is it is easier to get a blown engine to idle with big power. The more power per cubs means a not so good idle. Garry has gotten 900hp on 87 octane with a big cube Donavan. 1100 with 93. The 900 idled nicer. Could be a fun project. But like my project it may not turn out as expected. I am glad I did it because now I know. Frustrating because everybody was blowing smoke and I though we were doing something wrong. Not so Garry was right and most were wrong. Some times you just need to listen to the good old boys, Garry's Dad.

[The Hedgehog]

Long term reliability, meaning hundreds to thousands of hours, is a big difference to consider. 1.25 or less NA and you will get lots of hours. I like the sound of the 753ci..A 598 is easy to build with a standard tall deck. Should easily make 700-750hp and last.

Yep, above 598 and things seem to get kind of exotic.

I saw a bunch of info on an 808. Never heard of that being done on a marine engine but I see something different every day. From what I hear you should be able to do an 808 for around $50-60k. That would get you just north of 1,000hp. I would think that you could boost a 598 and get those numbers for a good bit less than that.

It is not that I plan to do anything like that, I just think that it is cool to ponder the big stuff.

[Rootsy]

A lot of CID isn't jack... Things really become interesting and longevity dwindles when you begin pushing the envelope of valve train capability. Efficiency is the name of the game.

What would you say if I told you that you can develop nearly 700 hp (quite possibly more now) from a 6 litre Gen III Chevy that has only had minor work done to it... With a supercharger... and drive it every day, to and from work... and then take it to the track, in 4wd and turn low 10's almost 9 seconds with it... all day long.... and it'll idle like a stock vehicle.

It's been done and currently is done... less than 20 miles from me.

[A2VeeDub]

A lot of CID isn't jack... Things really become interesting and longevity dwindles when you begin pushing the envelope of valve train capability. Efficiency is the name of the game.

What would you say if I told you that you can develop nearly 700 hp (quite possibly more now) from a 6 litre Gen III Chevy that has only had minor work done to it... With a supercharger... and drive it every day, to and from work... and then take it to the track, in 4wd and turn low 10's almost 9 seconds with it... all day long.... and it'll idle like a stock vehicle.

It's been done and currently is done... less than 20 miles from me.


If your gonna take this out of the water I'm gonna spit out a few VW numbers.

My car. Stock 2.0L internals, valve train etc, 17 psi turbo.
275 Wheel HP + 15% for drive loss= 316hp Thats 2.6HP/cid

My buddies car. Built 2.0 bottom end-forged rods, crank, pistons. Stock 20valve head (thats 5 valves/cylinder). 22 psi turbo.
400 wheel HP + 15%=460 hp. Thats 3.77hp/cid
Motor can handle more boost easily just can't keep the tires under it being front wheel drive.


My car has about 25,000 miles on it like this. My buddies has much less, but has had no issues.

[The Hedgehog]

A: This thread is more about hp/CID. It was prompted by a discussion about larger displacement engines. Yes, I did make reference to large CID and think that there is something cool to be done, but that is only a fraction of the post.

B: It is surely not about car engines. That is a whole different world. I really don't care what has or has not been done in a car. They don't push 6,500 lbs up hill at 5,000-6,000 rpm. Go do that in a car engine that does 3.5 hp/CID and you will melt it down quick.

The efficiency and what can be done with a valve train is a major point though.

[Rootsy]

A: This thread is more about hp/CID. It was prompted by a discussion about larger displacement engines. Yes, I did make reference to large CID and think that there is something cool to be done, but that is only a fraction of the post.

B: It is surely not about car engines. That is a whole different world.

The efficiency and what can be done with a valve train is a major point though.

An engine is an engine... it turns potential energy into kinetic energy + heat...

[blackhawk]

My old snowmobile engine made 3.75 hp per cubic inch. :D

[A2VeeDub]

A: This thread is more about hp/CID. It was prompted by a discussion about larger displacement engines. Yes, I did make reference to large CID and think that there is something cool to be done, but that is only a fraction of the post.

B: It is surely not about car engines. That is a whole different world. I really don't care what has or has not been done in a car. They don't push 6,500 lbs up hill at 5,000-6,000 rpm. Go do that in a car engine that does 3.5 hp/CID and you will melt it down quick.

The efficiency and what can be done with a valve train is a major point though.

Sorry for getting off your original topic. I agree with your point 100%. The amount of heat generated at that hp/cid and that load range is a lot more than an engine can get rid of efficiently.

[The Hedgehog]

An engine is an engine... it turns potential energy into kinetic energy + heat...

That is oversimplifying things first of all and secondly this is donzi.net and I am talking about marine stuff.

If it is so simple name one marine engine builder that is breaking 2.0 hp/CID by any significant margin? Just one

There is a HUGE difference between getting something to live for a few seconds vs pushing a boat. That has been proven time and again.

[VetteLT193]

That is oversimplifying things first of all and secondly this is donzi.net and I am talking about marine stuff.
If it is so simple name one marine engine builder that is breaking 2.0 hp/CID by any significant margin? Just one
There is a HUGE difference between getting something to live for a few seconds vs pushing a boat. That has been proven time and again.

in typical donzi.net fashion, I thought you mis-spelled the thread title and meant "HP per Cuban inch" which we all know it takes very little power to go 90 miles. :bonk:

in all seriousness, Merc gets right to the 2.0 per inch mark and those suckers are pretty well maxed out... how many hours do they last, and how much is a rebuild on 1075's?

[Rootsy]

That is oversimplifying things first of all and secondly this is donzi.net and I am talking about marine stuff.
If it is so simple name one marine engine builder that is breaking 2.0 hp/CID by any significant margin? Just one
There is a HUGE difference between getting something to live for a few seconds vs pushing a boat. That has been proven time and again.

There is no difference between a marine engine and say the tortures endured by a winston cup engine on any given weekend. Or even a round round engine that runs an entire season on the dirt track...

Any engine run at a near 100% load for extended periods falls into the same category.

[The Hedgehog]

in typical donzi.net fashion, I thought you mis-spelled the thread title and meant "HP per Cuban inch" which we all know it takes very little power to go 90 miles. :bonk:
in all seriousness, Merc gets right to the 2.0 per inch mark and those suckers are pretty well maxed out... how many hours do they last, and how much is a rebuild on 1075's?

Funny stuff!

1075's are expensive. I think that they get somewhere around 100 hours. I am sure that someone post the real number. They cost between $25-35k to freshen. They are 565 CID. Good engines. Merc makes a 1,200, I think it is a race gas engine.

Teague's 1,100's get around 150-200 hours. I dunno about the 1,200's, the jury is still out on those.

Eddie's 1,200's get around 150 hours.

I dunno what Sterling recommends on their big dogs or Eikert either.

From what I am told there is a big difference between what it takes to make just north of 1,000 and 1,200. That is where you start getting into more exotic valve trains.

I have a friend that has some of Eddie's 950's. They make around 1,000 hp and he has around 230 hours on them. My guess is that he will freshen them after this season. All he has done so far is change the oil and plugs.

[The Hedgehog]

There is no difference between a marine engine and say the tortures endured by a winston cup engine on any given weekend. Or even a round round engine that runs an entire season on the dirt track...
Any engine run at a near 100% load for extended periods falls into the same category.

So are you saying you can put an oval track engine in a boat and it will be good to go?

I agree with you on the torture thing. I actually think that an oval track engine goes through worse conditions and I think it is still apples and oranges.

[Donzi_Dude]

This thought was prompted by a discussion between Eddie Young and myself about building large N/A engines. Although I am not doing anything for a while, I like to fantasize about some cool ideas (like maybe a HUGE N/A). There seems to be a breakpoint in cu inch/Hp where it is better to go with a blown engine as extracting big power from a N/A setup requires HUGE cams and exotic valve trains etc, In hashing out these numbers this is what I found:
1.25 = Nice rule of thumb for reliable setup that is not too costly to build. It would either be solid off the shelf parts for N/A or a well tuned stocker (mag with forged internals) and 5-6 lbs of boost
1.35 - 1.4 = This would be a more aggressive setup. Finely tuned N/A with high flowing heads, bigger cam, high compression and more aggressive tune or a boosted Blue engine.
1.5 - 1.75 = This would be a fairly aggressively tuned boosted engine. It requires a combo of higher boost (7.5-9lbs), high flowing heads, a well selected cam and careful tune.
2.0 = This is big stuff to built by the pros only. Big Boost (think 12-15 lbs), huge heads, big tube exhaust, and very precise tune.
Is this consistent with what others are seeing?




i would tend to agree with you stament for the most part. im sure a few outliars can be built.
it does seem somewhat contradictory to what you posted here:




Happens all the time and I have seen the dyno sheets.

[Rootsy]

So are you saying you can put an oval track engine in a boat and it will be good to go?

I agree with you on the torture thing. I actually think that an oval track engine goes through worse conditions and I think it is still apples and oranges.

Reversion will be an issue and I am not so sure the sterndrives will handle the RPM... Otherwise... no reason why not.

I am being serious...

[joseph m. hahnl]

A lot of CID isn't jack... Things really become interesting and longevity dwindles when you begin pushing the envelope of valve train capability. Efficiency is the name of the game.

What would you say if I told you that you can develop nearly 700 hp (quite possibly more now) from a 6 litre Gen III Chevy that has only had minor work done to it... With a supercharger... and drive it every day, to and from work... and then take it to the track, in 4wd and turn low 10's almost 9 seconds with it... all day long.... and it'll idle like a stock vehicle.

It's been done and currently is done... less than 20 miles from me.


Now say I was didn't want to go through all that because this would not be an option for me
"6 litre Gen III Chevy that has only had minor work done to it"

If I wanted to put a super charger on a stock 350 mag.

What are the chances of survival?
would an Alpha have a prayer of working?

[Rootsy]

So long as you don't fatigue the weak link in the chain... whatever that may be.

[The Hedgehog]

Reversion will be an issue and I am not so sure the sterndrives will handle the RPM... Otherwise... no reason why not.
I am being serious...

Two minor issues don't you think?

I am still thinking apples and oranges. Winston cup engines are built to run a few hours not over 100 hours. For that matter we could throw F-1 into the mix.

This does not mean that one that builds race car motors can not build marine motors. As you go up in hp the rules start to change. You need to run different tolerances to take advantage of cool water.

Is it possible for a marine to make 3-4 hp per CID? Sure. 15 years ago the 1075 merc seemed unpractical. It will be quite some time before it happens though.

[Rootsy]

Two minor issues don't you think?
I am still thinking apples and oranges. Winston cup engines are built to run a few hours not over 100 hours. For that matter we could throw F-1 into the mix.
This does not mean that one that builds race car motors can not build marine motors. As you go up in hp the rules start to change. You need to run different tolerances to take advantage of cool water.
Is it possible for a marine to make 3-4 hp per CID? Sure. 15 years ago the 1075 merc seemed unpractical. It will be quite some time before it happens though.

Sealing technology, surface finish technology, material usage and application. The stuff being used today by automotive manufacturers, some still cutting edge technology and in development, will eventually be phased into the small custom engine builders once it becomes more main stream and understood by those without Ph.Ds...

To think it has all been figured out would be naive. As a matter of example... The Eaton Gen VI supercharger that is just now replacing the obsolete crap of yesterday in the automotive market.... This thing makes turbochargers obsolete... But I bet it is so new that very very few people outside of the industry dealing with it directly truly understand who, how, what, why... We are talking hundreds of degrees of difference on the discharge side of the compressor when compared to the Gen V... Even more when compared to screw, centrifugal, etc chargers...

It isn't naive to think that in the next decade a 1075 could got 500 hours before new bearings, rings and valvetrain...

As I said in the beginning of this tread... If you don't beat up the valvetrain you can go A LOT longer between "freshening". It's all in the acceleration and jerk of the ramp profiles and the resulting motions from the roller to the valve tip...

[Pismo]

Pismo No such thing as hundreds of thousand hours, regardless. Now here is the issue, when you get big cubs you will find thaqt 1/2 inch push rods are a necessity. The next thing is it is easier to get a blown engine to idle with big power. The more power per cubs means a not so good idle. Garry has gotten 900hp on 87 octane with a big cube Donavan. 1100 with 93. The 900 idled nicer. Could be a fun project. But like my project it may not turn out as expected. I am glad I did it because now I know. Frustrating because everybody was blowing smoke and I though we were doing something wrong. Not so Garry was right and most were wrong. Some times you just need to listen to the good old boys, Garry's Dad.

First of all I said hundreds to thousands of hours which is very possible and is done all the time so my point stands.

[A2VeeDub]

As I said in the beginning of this tread... If you don't beat up the valvetrain you can go A LOT longer between "freshening". It's all in the acceleration and jerk of the ramp profiles and the resulting motions from the roller to the valve tip...

Why hasn't there been more interest in multi valve heads and overhead cams to eliminate all the problems associated with rockers and push rods?

[MOP]

Not knowing I have a question! There is much reference to valve train, I have always been of the belief that valve train issues only happen at higher RPM's. Are there problems at the RPM ranges we run?

[BlownCrewCab]

A lot of CID isn't jack... Things really become interesting and longevity dwindles when you begin pushing the envelope of valve train capability. Efficiency is the name of the game.

What would you say if I told you that you can develop nearly 700 hp (quite possibly more now) from a 6 litre Gen III Chevy that has only had minor work done to it... With a supercharger... and drive it every day, to and from work... and then take it to the track, in 4wd and turn low 10's almost 9 seconds with it... all day long.... and it'll idle like a stock vehicle.

It's been done and currently is done... less than 20 miles from me.


Mine doesn't quite make 700, But I have that Same set up and drive it every day, This past weekend I had to lay the smack on a GT Mustang on I95, starting at 70mph to 130+ he didn't have a prayer and I was hauling 1500lbs+ of outdrives in the back. I Gots the 4WD Too for when I need to do Boosted launches and lay the smack from a stop:yes: It is a kick azz motor.

[BigGrizzly]

As for durability of Winston pro engines, they are very durable considering the RPMs run and how long. All this is assembly and maintenance. As for the Eaton stuff, we used them on propane powered 90hp for the clean air reservoir duty. It brings the hp back up and better. there going on 9 years now.

[Rootsy]

As for durability of Winston pro engines, they are very durable considering the RPMs run and how long. All this is assembly and maintenance. As for the Eaton stuff, we used them on propane powered 90hp for the clean air reservoir duty. It brings the hp back up and better. there going on 9 years now.

Gen VI charger is brand new...

[blackhawk]

Sweet, I'm going to buy a couple Winston Cup engines. One to throw in the boat and one for a spare. They're cheap right?

[Conquistador_del_mar]

Mine doesn't quite make 700, But I have that Same set up and drive it every day, This past weekend I had to lay the smack on a GT Mustang on I95, starting at 70mph to 130+ he didn't have a prayer and I was hauling 1500lbs+ of outdrives in the back. I Gots the 4WD Too for when I need to do Boosted launches and lay the smack from a stop:yes: It is a kick azz motor.

I now understand what your handle means - literally a blown crew cab truck :bonk:I had wondered before now - lol. Bill

[BlownCrewCab]

I now understand what your handle means - literally a blown crew cab truck :bonk:I had wondered before now - lol. Bill


Yeah, some people thought it meant Blown up...... But, Yeah thats my daily driver:yes: I don't think I'll ever own a Non Boosted vehicle again. It is Waaayyyyyy Too much fun to drive. It's lowered (just leveled, Not dropped) and has front/Rear sway Bars, Good shocks and runs and handles like a sports car (for a 7k lb truck) it's a Ball. will do 140+ and Not one problem in 3 years (knock on wood)

[BigGrizzly]

The generation VI is new but Eaton has been around a long time and has always been a good product.

[mrfixxall]

I now understand what your handle means - literally a blown crew cab truck :bonk:I had wondered before now - lol. Bill


Bill is your dually a 454 tbi?

[Donzi_Dude]

400 wheel HP + 15%=460 hp. Thats 3.77hp/cid
Motor can handle more boost easily just can't keep the tires under it being front wheel drive.




i would be suprised if the loss was that high in such a driveline. more than likely 10% or under.

[Conquistador_del_mar]

Bill is your dually a 454 tbi?

It is a fuel injected Vortec. Bill

[mrfixxall]

It is a fuel injected Vortec. Bill

i have a huffer for a tbi unit,,238/85/16 will put that truck at 12/13 mpg :) and they will fit with no problems..

[A2VeeDub]

i would be suprised if the loss was that high in such a driveline. more than likely 10% or under.

Probably right cosidering straght cut gears and limited slip diff. Stock FWD transaxles can approach 20% loss and good setups can get down under 10% like you said. 15% is just a "generic" average number. Doesn't matter that much. So the number drops to 3.4-3.5 hp/cid. Point is 3-4 is doable in cars and pretty reliable. It seems to be much lower in boats. At least for now.

[The Hedgehog]

Gen VI charger is brand new...

No doubt that technology will find itself into the marine environment one day.

Tell me where I can find info on the Eaton VI. I would like to learn more about it.

This is good stuff. I wanted this thread to discuss not only what can or can not be done now but what may be possible in the future.

I can still see a good possibility for some big power diesels. I can also see closed loop injection being a more prevalent option. I think that I saw a post from Grizz saying that they were used in some of the Honda engines.