sorry for sounding condescending but i hate to see wrong info so every one who wants to build a great engine get the info from the pros ask them question and listen to what they say read there books watch there videos but i have found that TV show leave allot out and magazine don't always get it right
sorry for sounding condescending but i hate to see wrong info so every one who wants to build a great engine get the info from the pros ask them question and listen to what they say read there books watch there videos but i have found that TV show leave allot out and magazine don't always get it right
And look at the 3800 turbo cars on this very forum making 900 HP, hitting 9s in the 1/4 mile, and using stock bottom end and stock unported cylinder heads.
Yes, CFM is important, but so are a lot of other things, and simply concentrating on CFM will lead you to a land of diminishing returns. And yes, there are limits that certain engines may overcome and thus necessitate larger ports that flow more. Comparing the needs of a top fuel engine, to the needs of a typical gasoline engine, is just way off base. The air/fuel ratio on a top fuel engine is about 1.7:1, and the blower is compressing the mixture so much that it's an almost solid mass being pushed into the cylinder. It runs at almost the point of hydrolocking, and ignition happens from compression and the heat in the heads, after about 2 seconds at full throttle. The physics for such a mixture are very different from the 14.7:1 stoichiometric AFR value for standard gasoline engines.
Yes, 2 HP / CFM is a generalization of what you can expect if you can actually use all the CFM and spin high enough RPM to make that HP. But there's a lot more involved, if you want to talk about real world results.
2 hp per cfm is V8 engine not 4 cylinder or 6 cylinder or 12 cylinder as you have to do the math to see how much for you number of cylinders your engine has as for th 900 hp 3800 who has that because there is no proof that any one running a stock unported headed 3800 is making that type of power maybe 700 at really high boost . let me try with an example for a boosted engine let say you have a 400hp NA V8 with 200 cfm heads now you boost it to 14.8 psi so in theory the power should double right now lets take the same engine and just change the heads to 250 cfm intakes now it should in theory make 500 hp NA and if you boost it to the same 14.8 it in theory should now have 1000 HP but of course you could boost the first engine to a higher boost to make up for the lack of cylinder head flow but you will also have added heat to the intake charge with higher boost so it is harder to fight detonation and you have a less dense intake charge
[This message has been edited by engine man (edited 09-23-2015).]
Back in the day as in 1999. Just because Pontiac the company doesn't exist any more, and wasn't making their own V8 production engines for the last N years, doesn't mean the platform itself is dead. If it did, this forum wouldn't be here, because, you know, Pontiac's dead.
Are we talking about drag racing, street cars, or LeMans? Make up your mind. SBC does not dominate them all. Chevrolet/Cadillac have certainly been dominating their respective racing circuits, sure. There is a huge difference between the Gen IV and V engines, than what people mean when they say "SBC" though. When people say "SBC" they mean the first generation engines. When they talk about the Gen II engines, they say LT, when they talk about Gen III/IV engines, they say LS, and when they talk about Gen V engines, it's hard to know, because most people still seem to be quite confused by what they are. Some still call the Gen V engines LS engines, but they're quite different from the Gen III/IV engines.
I must be a lot older than you. When I say LT1 I'm talking about the original 1970 lt1. I'm a pontiac fan but were talking sbc here ,the chevy bb is just a sbc on steroids. Chevy used and you can read about this during the mystery motor years when chevrolet was still involved in racing, how they basically used the sbc blueprints. They had semisphivpcal heads and on and on . But that's history. They've went way past that. I know guys who still ooh and ahh over a set of camel hump heads and don't believe a set of vortecs can out flow those 2.02 valves. Ford came out with so many variations of bb in the late 60s and still couldnt hold a candle to the 1 version of bb chevys. Fast forward to the 90s. How many times has ford redesigned their small block. They went modular then went back and now their using flat plane cranks but in 5 to 10 years they'll be doing it again. Why.? Because the sbc was and still is the best engine design bar none. There's only one v8 from the 50s 60s and 70s that is still produced today by a major automaker and it wears a bowtie.
[This message has been edited by Silvertown (edited 09-23-2015).]
Originally posted by Silvertown: I must be a lot older than you. When I say LT1 I'm talking about the original 1970 lt1. I'm a pontiac fan but were talking sbc here ,the chevy bb is just a sbc on steroids. Chevy used and you can read about this during the mystery motor years when chevrolet was still involved in racing, how they basically used the sbc blueprints. They had semisphivpcal heads and on and on . But that's history. They've went way past that. I know guys who still ooh and ahh over a set of camel hump heads and don't believe a set of vortecs can out flow those 2.02 valves. Ford came out with so many variations of bb in the late 60s and still couldnt hold a candle to the 1 version of bb chevys. Fast forward to the 90s. How many times has ford redesigned their small block. They went modular then went back and now their using flat plane cranks but in 5 to 10 years they'll be doing it again. Why.? Because the sbc was and still is the best engine design bar none. There's only one v8 from the 50s 60s and 70s that is still produced today by a major automaker and it wears a bowtie.
I'd hardly call the current small block the same design as the original small block.
Originally posted by engine man: 2 hp per cfm is V8 engine not 4 cylinder or 6 cylinder or 12 cylinder as you have to do the math to see how much for you number of cylinders your engine has as for th 900 hp 3800 who has that because there is no proof that any one running a stock unported headed 3800 is making that type of power maybe 700 at really high boost . let me try with an example for a boosted engine let say you have a 400hp NA V8 with 200 cfm heads now you boost it to 14.8 psi so in theory the power should double right now lets take the same engine and just change the heads to 250 cfm intakes now it should in theory make 500 hp NA and if you boost it to the same 14.8 it in theory should now have 1000 HP but of course you could boost the first engine to a higher boost to make up for the lack of cylinder head flow but you will also have added heat to the intake charge with higher boost so it is harder to fight detonation and you have a less dense intake charge
You are not very good at this example thing are you? What has no proof are your examples. You're just taking arbitrary numbers with no actual merit to them. You said earlier that you need 300 CFM to make any power, regardless of engine size or number of cylinders, now you're saying the same 2 HP per CFM doesn't work as a generalization for anything other than V8s. Yes, if your heads can flow 300 peak CFM and you have all the necessary other components, you can make 600 HP N/A. With the right components and 300 CFM heads, you can make 700 HP N/A, too. But you don't need 300 CFM heads to make 600 HP with forced induction. You don't need it to make 600 HP with nitrous. There's a lot more to good head design than just flowing 300 CFM. You don't seem to understand that though.
darkhorizon and JustinBart's cars are making about 900 HP and I'm pretty sure they are on stock unported heads. And yes, they have meth injection and an intercooler, and I'm pretty sure that's on E85, not crappy low octane pump gas.
Also, just talking about peak HP is a waste of time. Area under the curve is what matters. If you want more torque, you need more displacement. If you want more HP, you need more torque at the same RPM, or more RPM with maintaining torque.
I'd hardly call the current small block the same design as the original small block.
Correct me if I'm wrong but I do believe the 1955 265 ci sbc had 2 valves per cylinder and push rods and as far as I know the new z06 has the same setup. But as fast as chevy has been moving up their game who knows. When the zora c8 hits the streets it's game over.
You can get into all kinds of pissing matches but engines can make power 6 ways to Sunday. It is all about volumetric efficiency. Like I stated you have to get the most air in and out of a cylinder to make the most power.
The reason many use V8 engines is that it is easier and cheaper to do so. I could make a 4 that will out perform about anything on the dyno but it gets very expensive and much more radical. If not for todays electronics and higher quality parts we would not have the engines we have today coming from the factory.
As in for what is faster you can not judge this way. You compare the engines on a Dyno. Like the Ferrari vs. the Typhoon means little as the type vehicle and delivery system effect things in different way. That part is all about how to get the power to the ground.
Even today with the Hellcat it has more power than it can use. They put up a big number but the truth is the engine management cuts back power to make it hook up. Putting the power to the ground is the greatest challenge but yet not compromise the car from normal driving. You can make a drag car but you would not want to drive it to work daily with 90/10 shocks.
As for HP it is the thunder but Torque does most all the work.
Wow i am reposting formula maybe if you read it you will understand it
the simple mathematical formula for calculating potential power for a V8 engine is to multiply the maximum flow bench CFM test data at 28 inches of test pressure by 2 to get the estimated horsepower capability. This means that porting modifications to cylinder heads and intake manifolds that increase airflow by 1 CFM can produce 2 horsepower in a V8 engine (1 CFM x .255 x 8 Cylinders = 2.04 HP). just get any porting book and they will say the same thing
Flow Bench The horsepower potential of an engine can be calculated by the airflow capability of the cylinder head and intake manifold. Airflow testing of cylinder heads and intake manifolds can be conducted on a flow bench. Horsepower calculations can be estimated from the flow bench test data as follows: The standard measure for flow testing is 28" of test pressure on a Superflow 600 flow bench. The formula for calculating horsepower from flow test data measured at 28" of test pressure is as follows:
HP = 0.255 x flow test data at 28 inches of test pressure
Example: Intake airflow of 250 cfm at 28" of test pressure can produce 510 hp. 250 cfm x .255 = 63.75 hp per cylinder 63.75 hp per cylinder x 8 cylinders = 510 hp.
so if you use the formula for a 6 cylinder will be 1cfm x .255 x 6 = 1.53 hp per cfm of flow so if you had a head that flows 250 cfm on the intake port then the HP potential is 1.53 x 250 = 382.5 hp this is the formula all shops use it is the standard
this is for a natueraly asperated engine this formula show why it is harder to get the same power out of the 4 cyl & 6 cyl as 8 cylinders
[This message has been edited by engine man (edited 09-24-2015).]
Originally posted by Silvertown: Correct me if I'm wrong but I do believe the 1955 265 ci sbc had 2 valves per cylinder and push rods and as far as I know the new z06 has the same setup. But as fast as chevy has been moving up their game who knows. When the zora c8 hits the streets it's game over.
I guess Ford's V8 was an SBC too because it had 2 valves per cylinder and push rods. So did Chrysler's. So did pretty much every pushrod V8 made in the last 100 years.
The bore spacing and deck height are the only things shared by the original SBC and the Gen III/IV/V engines. I guess you could say the bell pattern too, except for the LS4. Then current engines are closer to the original Pontiac V8, in terms of head design and pushing the limits with a pushrod V8, than they are to the original SBC.
[This message has been edited by dobey (edited 09-24-2015).]
I guess Ford's V8 was an SBC too because it had 2 valves per cylinder and push rods. So did Chrysler's. So did pretty much every pushrod V8 made in the last 100 years.
The bore spacing and deck height are the only things shared by the original SBC and the Gen III/IV/V engines. I guess you could say the bell pattern too, except for the LS4. Then current engines are closer to the original Pontiac V8, in terms of head design and pushing the limits with a pushrod V8, than they are to the original SBC.
You believe what you want to believe." If bore spacing" "deck height" two valves pc and push rods is not the original receipe. The engine has morphed around those parameters it's called evolution. And the evolution began in 1955 as a revolution and has systematically made every engine try catch it and fail. All the engines that are so ballyhooed by mopar dodge ford are extinct because they had inefficient designs.the op was engine size vs power and the sbc is the perfect balance of the two. That's why your putting one in a fiero even though I believe that's a inefficient use of a sbc with a horizontal transaxle. And for the record the 1955 sbc was based on Ford's flat top dimensions.But you don't see them going in t buckets, 32 coupes anymore. I've watched ford guys do these build ups and stuff a sbc crate motor in them. And in jaguars, ferraris, shelby cobras and and on
[This message has been edited by Silvertown (edited 09-24-2015).]
You believe what you want to believe." If bore spacing" "deck height" two valves pc and push rods is not the original receipe. The engine has morphed around those parameters it's called evolution. And the evolution began in 1955 as a revolution and has systematically made every engine try catch it and fail. All the engines that are so ballyhooed by mopar dodge ford pontiac are extinct because they had inefficient designs.the op was engine size vs power and the sbc is the perfect balance of the two. That's why your putting one in a fiero even though I believe that's a inefficient use of a sbc with a horizontal transaxle. And for the record the 1955 sbc was based on Ford's flat top dimensions. But you don't see them going in t buckets, 32 coupes anymore. I've watched ford guys do these build ups and stuff a sbc crate motor in them. And in jaguars, ferraris, shelby cobras and and on
[This message has been edited by Silvertown (edited 09-24-2015).]
Arthur Chevrolet was awarded US Patent #1,744,526 for an overhead valve engine design. This patent included an adapter that could be applied to an existing engine, thus transforming it into an Overhead Valve Engine.
In 1949, Oldsmobile introduced the Rocket V8. It was the first high-compression I-head design, and is the archetype for most modern pushrod engines.
and as far as ford engines not making power the 351 Cleveland with stock 4 barrel heads that are ported can make a ton of power as i have seen it with my own eyes at school we had a stroked 351 to 377 ci with those heads and solid roller cam and it made 600 + hp it made more power than my 454 BBC with a roller cam
[This message has been edited by engine man (edited 09-24-2015).]
Originally posted by Silvertown: That's why your putting one in a fiero even though I believe that's a inefficient use of a sbc with a horizontal transaxle.
I'm putting an engine built from an LS4 block in the Fiero because it's close in design to the original Pontiac V8, and it's an interesting challenge.
Sorry, but I don't worship any one particular type of engine like the SBC, and like you seem to do. They are tools, and I just try to pick something interesting, that falls into the same manufacturer's realm, and will allow me to achieve the goals I want for the car.
I don't get your "I believe that's an inefficient use of an SBC" though.
I'm putting an engine built from an LS4 block in the Fiero because it's close in design to the original Pontiac V8, and it's an interesting challenge.
Sorry, but I don't worship any one particular type of engine like the SBC, and like you seem to do. They are tools, and I just try to pick something interesting, that falls into the same manufacturer's realm, and will allow me to achieve the goals I want for the car.
I don't get your "I believe that's an inefficient use of an SBC" though.
The transaxle is the problem. Front wheel drive V8s have never from the eldorado/tornado to the last montecarlo/gp been efficient enough to generate a following. But v6s have. I've owned pontiacs, chevrolets, Ford's and toyotas so I'm not that big of a fan as some stallllwarts. But having driven a good many miles behind the wheel of theses cars excluding the exotics in Vegas the small block chevys are more reliable less thirsty like my ss454 parts are plentiful and it don't take much to keep them alive and running. My 68 c10 original 327 is testimony on that point. Leaking oil, rings and valve seals and she still kept trucking till the day I sold it.
Arthur Chevrolet was awarded US Patent #1,744,526 for an overhead valve engine design. This patent included an adapter that could be applied to an existing engine, thus transforming it into an Overhead Valve Engine.
In 1949, Oldsmobile introduced the Rocket V8. It was the first high-compression I-head design, and is the archetype for most modern pushrod engines.
and as far as ford engines not making power the 351 Cleveland with stock 4 barrel heads that are ported can make a ton of power as i have seen it with my own eyes at school we had a stroked 351 to 377 ci with those heads and solid roller cam and it made 600 + hp it made more power than my 454 BBC with a roller cam
Where is 351 cleveland now? Extinct! Where's the rocket 88? Extinct. Next!
Originally posted by Silvertown: The transaxle is the problem. Front wheel drive V8s have never from the eldorado/tornado to the last montecarlo/gp been efficient enough to generate a following. But v6s have. I've owned pontiacs, chevrolets, Ford's and toyotas so I'm not that big of a fan as some stallllwarts. But having driven a good many miles behind the wheel of theses cars excluding the exotics in Vegas the small block chevys are more reliable less thirsty like my ss454 parts are plentiful and it don't take much to keep them alive and running. My 68 c10 original 327 is testimony on that point. Leaking oil, rings and valve seals and she still kept trucking till the day I sold it.
Not efficient in what sense? How is the transaxle the problem?
Originally posted by Lambo nut: Ummm, you might want to get your money back.
Kevin
a 350 chevy is 43.75 cubic inches for each cylinder but i did do the cubic feet wrong it should be .025318287 not even 1 cubic foot ya i messed up i only devided by 12 when it should have been 1728 witch is 12 x 12 x 12 = 1728 square inches in 1 square foot
[This message has been edited by engine man (edited 09-24-2015).]
well dobey you cant even understand the formula posted but i will say you do a good job at twisting thing to fit the way you want them by the way are you ever going to get your car done you seem to have advice for every one but after 5 years your car is still not together
well dobey you cant even understand the formula posted but i will say you do a good job at twisting thing to fit the way you want them by the way are you ever going to get your car done you seem to have advice for every one but after 5 years your car is still not together
What formula don't I understand? Math is math, but that formula is almost entirely useless for building a real engine. You don't need 300 CFM heads to make 600 HP, especially not with a turbo. I said it before, and I'll say it again, you need the full package. Knowing some theoretical value isn't going to help you actually make any power. Worst thing it will do is make you waste money on crap you don't need. And yeah, I'm sorry, a 3.64 cubic foot 1 cylinder engine could turn about 225 RPM with 364 CFM, at 100% efficiency.
If you are in such a hurry for my car to get done, then you're welcome to give me a million dollars so I can have the necessary work space to get it done, and not have to worry about a day job, and all the other crap I have to do. If not, then STFU. My car will get done when I decide it will be done, and it's none of your concern when that is or is not. Keep your ad hominem to yourself.
see that is the problem you are telling GM , Ford and the rest of the automotive community that the formula they use on NA engine and Turbo charged engine don't matter . since that formula is not worth any thing then i should be able to get 900 hp from a GM 2.8 with the stock heads LOL
see that is the problem you are telling GM , Ford and the rest of the automotive community that the formula they use on NA engine and Turbo charged engine don't matter . since that formula is not worth any thing then i should be able to get 900 hp from a GM 2.8 with the stock heads LOL
Not so. But you guys always want to paint the perfect scenario as in your beefed up motor against some vanilla sbc.a thimble sized engine may put out a 1000 hp but a 455 hp detroit diesel will drag you all over the parking lot in figure eights in a tug of war.
Extinct because they aren't in new production vehicles? Whoop, then the SBC is extinct too! Yay for evolving engine platforms.
The sbc is not extinct. Pontiac. Is and for good reason. Chevrolet smart. Pontiac dumb. As in not developing their own engines. Why because the small block chevy was better.
Originally posted by Silvertown: The sbc is not extinct. Pontiac. Is and for good reason. Chevrolet smart. Pontiac dumb. As in not developing their own engines. Why because the small block chevy was better.
The SBC is equally as extinct as a Pontiac.
No, it has nothing to do with the Chevy being better. It has everything to do with corporate structure. The Gen II/III/IV/V engines are not "Chevrolet" engines. They are GM Powertrain engines. Having divisions within the same company competing to design engines is just stupid and a horrible waste of money. Engineers from all of the subsidiaries now design together the same engine, to reduce cost. Pontiac being shut down had nothing to do with engines, and everything to do with the brand being turned into mediocrity by poor leadership.
The SBC is done. It was last used in production over 12 years ago. Stop trolling with this nonsense. It is irrelevant to the thread.
No, it has nothing to do with the Chevy being better. It has everything to do with corporate structure. The Gen II/III/IV/V engines are not "Chevrolet" engines. They are GM Powertrain engines. Having divisions within the same company competing to design engines is just stupid and a horrible waste of money. Engineers from all of the subsidiaries now design together the same engine, to reduce cost. Pontiac being shut down had nothing to do with engines, and everything to do with the brand being turned into mediocrity by poor leadership.
The SBC is done. It was last used in production over 12 years ago. Stop trolling with this nonsense. It is irrelevant to the thread.
If you cracked open a book and read about engine development history from the beginning this discussion wouldn't be happening. But for time constraints I will acquiesce to your so called knowledge.
see that is the problem you are telling GM , Ford and the rest of the automotive community that the formula they use on NA engine and Turbo charged engine don't matter . since that formula is not worth any thing then i should be able to get 900 hp from a GM 2.8 with the stock heads LOL
No. I'm telling you that a formula that has no practical merit, is useless. If you can show me one single street car with a naturally aspirated engine, making anywhere close to the maximum horsepower from having that formula, then I'll say otherwise. But it's not going to happen. You'd be hard pressed to even find a race car that makes as much power as that formula tells you that they can make.
To even pump 300 CFM through each cylinder, my engine (0.030 over 287 is 292 cid) will have to spin to over 28000 RPM. A 6.2L engine would have to turn over 22000 RPM. Here's a formula for you:
(CID x RPM / 3456) * VE = CFM
That tells you how much CFM your engine will be able to flow at any given RPM and VE. You must supply that much air in order for that VE to be met. Less air means lower VE. Having an intake pipe to the cylinder that can supply more will help, up to a point, but you cannot physically pump more air through the system. With some fancy tuning of the valve timing, you may be able to get just slightly over 100% VE, but in a N/A engine, you're not likely to see that unless it's a full race engine. A very high performance street engine might see close to 90-95% VE, but probably not more so. How the peak CFM of a head fits into that picture, depends on the valve train. Having a head that flows its peak CFM at some point outside the operating range of your valve train, is not useful. You need a valve train that will give you the highest VE with the heads you use, to be able to meet the CFM requirements, so the engine can rotate and provide power.
Not so. But you guys always want to paint the perfect scenario as in your beefed up motor against some vanilla sbc.a thimble sized engine may put out a 1000 hp but a 455 hp detroit diesel will drag you all over the parking lot in figure eights in a tug of war.
your right the diesel will drag it all over but the heads have to flow a certain amount to make all that torque in other words you can't push enough air though a straw sized intake port no matter how much boost you have. to make a engine gas or diesel make its power the port must flow enough air NA or forced induction to make the power
Well GM is all corporate engines and has been for years.
While we can call the LT a GM powertrain engine it is funded mostly by the Chevy division since they use about 98% of them.
While the engine is called a Small Block by name it has left all the things of the original engine far behind and is a totally modern engine. It really is amazing to get inside one of these engines and see just how well built they are today.
Pontiac died over the years due to mismanagement. After Delorean left them GM really did not understand them or know what to do with them. The engineers at Pontiac were some of the best and the engines and Suspensions were key to what made them a Pontiac. Sharing platforms was nothing new but Delroean, Knudsen and Estes let the engineers loose and they had some of the best in the era. What is sad what was turned down in the 60's by GM that would have transformed the division. They had plans on FI. Radial tires in 1965, OHC and DOHC V8 engines. Euro composite head lamps. Better suspension tuning. 4 wheel Disc Brakes in 1965. All were killed.
Segway forward to 1979 the Pontiac V8 was killed and being an enthusiast car you ripped the heart our of the car many loved. Many of these guys bought modified and raced Pontiac because of the engine. This lost many in the early 80's
Pontiac then tried to rely on styling to move them forward. The TA, Fiero, Grand Am and Bonneville all help revive sales and saved them from being shut down before Olds. But the division was really killed when they removed the only RWD car they had and tried to sell cars like the Aztek, G3 and cars like the G5 and G6 and not even offer a Performance Engine of any kind. Imagine a G6 with a 260 HP Turbo or even the G4 which was already built on the line with the Cobalt SS. One was built and rejected. I saw it and they ran parts at the plant with it.
GM is going to have a new line of engines soon. Cadillac is going to make their own 4-6-8 in the coming years with more advanced technology and more power. These will not be based on the other engines and will not be shared. GM has learned the value of exclusive in a premium brand and the profits in this segment are such to let them do this. It will take time but I image we will see some special engines this time. No Short Cut N Star this time.
Originally posted by Silvertown: If you cracked open a book and read about engine development history from the beginning this discussion wouldn't be happening. But for time constraints I will acquiesce to your so called knowledge.
Oh look, he's trying to be condescending, how precious.
If you'd read about engine development history past the time of the SBC, this discussion wouldn't be happening. The current engines are not SBCs. They are GM corporate engines. The SBC is no longer in production. Yes, there are crate engines available, but you cannot go buy a new car or truck with an SBC in it. There are Pontiac crate engines available too, or small block Ford, or Mopar. You'd know the SBC hasn't been used in production for over 12 years now.
your right the diesel will drag it all over but the heads have to flow a certain amount to make all that torque in other words you can't push enough air though a straw sized intake port no matter how much boost you have. to make a engine gas or diesel make its power the port must flow enough air NA or forced induction to make the power
The diesel turns less than 2000 rpms at 75 mph so you can wind up any little motor of your choice and get your crank snapped in two from the torque of a diesel pulling you backwards. You can flow all the air you want at high speed but torque gets you moving first and how you do that I give up.
Oh look, he's trying to be condescending, how precious.
If you'd read about engine development history past the time of the SBC, this discussion wouldn't be happening. The current engines are not SBCs. They are GM corporate engines. The SBC is no longer in production. Yes, there are crate engines available, but you cannot go buy a new car or truck with an SBC in it. There are Pontiac crate engines available too, or small block Ford, or Mopar. You'd know the SBC hasn't been used in production for over 12 years now.
