100 horsepower per liter naturally aspirated
07-10-2007, 10:14 PM
#701
Originally Posted by EdmontonSS
I didn't see the idiocy in the original post at all... It was a perfectly fine post. I can see someone taking offence to the wording combination "import car makers" and "lofty goal". And I think you've made your point clear, that hp/L, considered in isolation, is not a great "goal" for any engine. Pretty much anything related to the original question after that was in defence from the "hp/L doesn't matter" crowd...
Seriously, read back over the original poster's first and second post... He's looking for ideas to improve his engine, and is looking to "build on the foundation" he already has, but was looking for ideas to improve specific output as opposed to displacement. It's not like he came on here saying hp/L was the end-all and be-all, he just wanted to know why other engines could get x amount of specific output and this one can't. ... Using inflamitory terms like "ricer math" and "idiocy". . .
Seriously, read back over the original poster's first and second post... He's looking for ideas to improve his engine, and is looking to "build on the foundation" he already has, but was looking for ideas to improve specific output as opposed to displacement. It's not like he came on here saying hp/L was the end-all and be-all, he just wanted to know why other engines could get x amount of specific output and this one can't. ... Using inflamitory terms like "ricer math" and "idiocy". . .
I made a technical assesment and QuickDoubleNickel thanked me, EdmontonSS commented on it with adjustments he'd make, PatrickG said it was good stuff and commented on trying it with his motor, and hammertime PM'd me in support. The fact that at least 5 board members want to discuss it is reason enough for the discussion to occur.
Mike
07-10-2007, 10:24 PM
#702
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Originally Posted by engineermike
As stated in my technical post, the goal was to keep idle quality good, emissions low, and mpg high. I believe a well-engineered 350 can reach 570 hp and get better gas mileage and lower emissions than a 570 hp 427.
Mike
Mike
As stated in my technical post, the goal was to keep idle quality good, emissions low, and mpg high.
07-10-2007, 10:36 PM
#703
Originally Posted by engineermike
As stated in my technical post, the goal was to keep idle quality good, emissions low, and mpg high. I believe a well-engineered 350 can reach 570 hp and get better gas mileage and lower emissions than a 570 hp 427.
Mike
Mike
Trying to make the same amount of power with larger cubes eventually places a limit on the bore for emissions controls, which get tighter as time passes. Perhaps DI can help offset this some, but its hard to imagine continually larger engines being able to attain SULEV certification. At some point, the only alternatives will be more cylinders or larger strokes, both of which will increase the package size. Specifically, longer strokes will place a limit on piston speed, forcing a reduction in rpm to maintain reasonable limits.
I think these are the answers to why there will need to be a limit on displacement. Was the 5.7L figure arbitrary? Quite possibly so. That said, I think we will find a limit on how large an engine can be and still hit all the mileage and emissions targets necessary to get the greenlight for production.
07-10-2007, 11:11 PM
#705
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Originally Posted by racer7088
I am surprissed this thread is still going on but I guess it isn't bad as long as people can see the big picture.
TQ/CID is mostly tied to engine size and is usually around 1.25 Ft.lbs./CID on a normal pump gas engine.
Without a blower or turbo etc. you can't expect higher than a certain VE to be acheived which is already being acheived in most of these street engines with good tuning.
The rest of your TQ/CID is tied up in engine efficiency as in friction reduction and combustion efficiency etc. and all the players are relatively close as well.
So basically TQ/CID has remained relatively constant where as HP/CID has slowly risen throughout the years.
So since TQ/CID is relatively constant HP/CID is mostly tied to the rpm that the engine in question can keep breathing till. This is the specific HP you guys are of course talking about.
So basically anything allowing more rpm to be acheived will raise your specific power or HP/CID or HP/L.
The problem with thinking that way is that I can simply destroke any given engine and now the heads and cam that petered out at say one rpm will go to a newer and higher rpm and make almost the same power while simply acheiving it at a higher rpm. This will be a worse engine with less power that does not last as long at that same power level.
TQ/CID is mostly tied to engine size and is usually around 1.25 Ft.lbs./CID on a normal pump gas engine.
Without a blower or turbo etc. you can't expect higher than a certain VE to be acheived which is already being acheived in most of these street engines with good tuning.
The rest of your TQ/CID is tied up in engine efficiency as in friction reduction and combustion efficiency etc. and all the players are relatively close as well.
So basically TQ/CID has remained relatively constant where as HP/CID has slowly risen throughout the years.
So since TQ/CID is relatively constant HP/CID is mostly tied to the rpm that the engine in question can keep breathing till. This is the specific HP you guys are of course talking about.
So basically anything allowing more rpm to be acheived will raise your specific power or HP/CID or HP/L.
The problem with thinking that way is that I can simply destroke any given engine and now the heads and cam that petered out at say one rpm will go to a newer and higher rpm and make almost the same power while simply acheiving it at a higher rpm. This will be a worse engine with less power that does not last as long at that same power level.
Sad because you could take an LS7 and destroke it to about 5L, make almost 100 peak bhp / L, and this engine would impress some people more than the current LS7. It would have a peaky power curve, wouldn't make as much torque, and wouldn't last as long or be as reliable, yet to the ignorant would still appear to be a big improvement.
Originally Posted by racer7088
Now the good way to increase specific power is through better heads cams and intake/exhaust etc. that allows the same CID engine to now develop it's TQ to a higher rpm and make more power not less. This engine will also have higher specific output but actually high HP too so you will truly get better performance.
The advantage to the 4V DOHC is mainly in the small light valves that do not have to be opened as far and the more rigid setup without the pushrods which allows a lot higher rpm ceiling and thus more potential power per liter or CID. The penalty though is more complexity, weight and frictional losses as well as a larger engine that doesn't package as well.
Unless you are spinning extreme rpm the breathing differences are not that great and the lower friction of the lower rpm pushrod stuff allows almost identical TQ/CID whle the packaging allows more cubic inches and thus more power in the same packaging space ala LS7. The engines that are in the same or higher HP range as the LS7 are huge in comparison and do not make as high a mileage either.
Of course for civility and low speed idle the much better low and mid lift breathing of the good 4V stuff which allows for a lower duration camshaft with much less overlap will always beat the 2V stuff in that arena. I don't think anyone would argue that.
So in retrospect you can always run a larger engine in the same package area with the pushrod design though and then spin it lower in rpm to make the same power and that's the real reason the LSX family shines. Very large displacement engine with great 2V heads so total hp and total tq are both much higher in general which is what makes for a nice street car.
The advantage to the 4V DOHC is mainly in the small light valves that do not have to be opened as far and the more rigid setup without the pushrods which allows a lot higher rpm ceiling and thus more potential power per liter or CID. The penalty though is more complexity, weight and frictional losses as well as a larger engine that doesn't package as well.
Unless you are spinning extreme rpm the breathing differences are not that great and the lower friction of the lower rpm pushrod stuff allows almost identical TQ/CID whle the packaging allows more cubic inches and thus more power in the same packaging space ala LS7. The engines that are in the same or higher HP range as the LS7 are huge in comparison and do not make as high a mileage either.
Of course for civility and low speed idle the much better low and mid lift breathing of the good 4V stuff which allows for a lower duration camshaft with much less overlap will always beat the 2V stuff in that arena. I don't think anyone would argue that.
So in retrospect you can always run a larger engine in the same package area with the pushrod design though and then spin it lower in rpm to make the same power and that's the real reason the LSX family shines. Very large displacement engine with great 2V heads so total hp and total tq are both much higher in general which is what makes for a nice street car.
07-10-2007, 11:16 PM
#706
Originally Posted by engineermike
As stated in my technical post, the goal was to keep idle quality good, emissions low, and mpg high. I believe a well-engineered 350 can reach 570 hp and get better gas mileage and lower emissions than a 570 hp 427.
Mike
Mike
If cost is a factor, then I'd say it wouldn't be the best of ideas to keep to 346 and try for 570 hp, good idle quality, and mpg high. Going with the 6.2 L LS3, you can get acceptable mileage and hit the goal with a LOT less $$. So if you're looking for a specific performance goal (such as mpg, which is a kind of "performance") and not just an arbitrary cube limit, then it completely changes the game. With DoD, I'd say you can and should go even higher in cubes.
(Oh, and since he said production engine I guess we have to stick with carb legal headers)
07-10-2007, 11:19 PM
#707
Originally Posted by hammertime
I think these are the answers to why there will need to be a limit on displacement. Was the 5.7L figure arbitrary? Quite possibly so. That said, I think we will find a limit on how large an engine can be and still hit all the mileage and emissions targets necessary to get the greenlight for production.
07-11-2007, 07:43 AM
#708
As an example of a non-arbitrary question that is along the same lines:
"The 2008 Dodge Viper has 600 HP. How could we beat that (say, by at least 50 HP) using the LS architecture and keeping naturally aspirated and steetable production idle, getting at least as good MPG as the Viper, etc? Remember that this will have to be a production engine, so you will be limited to CARB headers, passing emissions, etc."
Since the max displacement of the LS architecture is less than that of the Viper, then it will require some serious hp/L. But as a consequence, not as an arbitrary primary.
Do you see how that question is in an entirely different ball park? (i.e. the real world, and basing the parameters on non-arbitrary things?)
"The 2008 Dodge Viper has 600 HP. How could we beat that (say, by at least 50 HP) using the LS architecture and keeping naturally aspirated and steetable production idle, getting at least as good MPG as the Viper, etc? Remember that this will have to be a production engine, so you will be limited to CARB headers, passing emissions, etc."
Since the max displacement of the LS architecture is less than that of the Viper, then it will require some serious hp/L. But as a consequence, not as an arbitrary primary.
Do you see how that question is in an entirely different ball park? (i.e. the real world, and basing the parameters on non-arbitrary things?)
07-11-2007, 08:42 PM
#709
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I just skimmed through this thread but I like racer7088's responses a lot. I can clearly see where hp/L is a good engineering comparision between similiar motors but I completely enjoy the flaming of the "ricer" minded crowd that doesn't understand that hp/L isn't a good comparision of end performance between engines with completely different build goals and designs.
Whether they mean well or not they still need to understand that you can't compare a high hp/L DOHC motor to a LS motor with hp/L purely on the idea of understanding end-user performance. It isn't an accurate comparision for what the build goals were or of the performance. Which is what the originator of this thread was doing.
Although I wouldn't bet much that the GM small block OHV engines won't be seeing a lot of the benefits that make some of those OHC motors make those high hp/L numbers in the future. I think GM sandbags for marketing reasons...
Whether they mean well or not they still need to understand that you can't compare a high hp/L DOHC motor to a LS motor with hp/L purely on the idea of understanding end-user performance. It isn't an accurate comparision for what the build goals were or of the performance. Which is what the originator of this thread was doing.
Although I wouldn't bet much that the GM small block OHV engines won't be seeing a lot of the benefits that make some of those OHC motors make those high hp/L numbers in the future. I think GM sandbags for marketing reasons...
07-11-2007, 11:47 PM
#710
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Originally Posted by black_knight
As an example of a non-arbitrary question that is along the same lines:
"The 2008 Dodge Viper has 600 HP. How could we beat that (say, by at least 50 HP) using the LS architecture and keeping naturally aspirated and steetable production idle, getting at least as good MPG as the Viper, etc? Remember that this will have to be a production engine, so you will be limited to CARB headers, passing emissions, etc."
Since the max displacement of the LS architecture is less than that of the Viper, then it will require some serious hp/L. But as a consequence, not as an arbitrary primary.
Do you see how that question is in an entirely different ball park? (i.e. the real world, and basing the parameters on non-arbitrary things?)
"The 2008 Dodge Viper has 600 HP. How could we beat that (say, by at least 50 HP) using the LS architecture and keeping naturally aspirated and steetable production idle, getting at least as good MPG as the Viper, etc? Remember that this will have to be a production engine, so you will be limited to CARB headers, passing emissions, etc."
Since the max displacement of the LS architecture is less than that of the Viper, then it will require some serious hp/L. But as a consequence, not as an arbitrary primary.
Do you see how that question is in an entirely different ball park? (i.e. the real world, and basing the parameters on non-arbitrary things?)
We got 650 HP out of an 6.7L LS2 block. Weren't going for peak HP, just power to match.
You can read about the build in the LSx Engine Special of the Jan/Feb 07 Sand Sports Magazine Article Titled "POWERHOUSE"
Smooth idle and check the low bsfc. Should get decent gas mileage.
Click for charts
With enough donations we could pull the engine, put it on the dyno and get 670 out of it.
07-11-2007, 11:59 PM
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Originally Posted by 04GoatBoy
We got 650 HP out of an 6.7L LS2 block. Weren't going for peak HP, just power to match.
You can read about the build in the LSx Engine Special of the Jan/Feb 07 Sand Sports Magazine Article Titled "POWERHOUSE"
Smooth idle and check the low bsfc. Should get decent gas mileage.
Click for charts
With enough donations we could pull the engine, put it on the dyno and get 670 out of it.
You can read about the build in the LSx Engine Special of the Jan/Feb 07 Sand Sports Magazine Article Titled "POWERHOUSE"
Smooth idle and check the low bsfc. Should get decent gas mileage.
Click for charts
With enough donations we could pull the engine, put it on the dyno and get 670 out of it.
Or 650HP/Camshaft
.....probably does alright in the torque department too.Too bad it sucks because it only makes 97HP/L
07-12-2007, 12:03 AM
#712
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Originally Posted by Louie83
Damn....That is over 1.4 HP/lb.
Or 650HP/Camshaft .....probably does alright in the torque department too.
Too bad it sucks because it only makes 97HP/L
Or 650HP/Camshaft
.....probably does alright in the torque department too.Too bad it sucks because it only makes 97HP/L
>>>
08-12-2007, 01:16 PM
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Wow i cant believe this became a 36 page thread......its funny people act like the lsx is an ancient fossil trying to catch up to the vvt 4 bangers and the dohc cars,but in fact were whooping *** everyday from the tracks of le mans to the streets of america.
If it aint broke dont fix it! lsx FTMFW
If it aint broke dont fix it! lsx FTMFW
08-19-2007, 02:48 PM
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Originally Posted by engineermike
I'm sure that 248/252 solid roller will have a glass-smooth "streetable production idle" too. . .
And i haven't started the fine tuning yet.
08-19-2007, 04:03 PM
#717
Originally Posted by 04GoatBoy
And i haven't started the fine tuning yet.
[edit]Are you actually trying to say that a 248/252 solid roller has a production idle???[/edit]
08-21-2007, 01:02 AM
#718
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Originally Posted by engineermike
Idle it down to 550 rpm rpm and if it has no distinguishable chop at all, THEN it can be a production cam.
[edit]Are you actually trying to say that a 248/252 solid roller has a production idle???[/edit]
[edit]Are you actually trying to say that a 248/252 solid roller has a production idle???[/edit]
From Wizardry 8, "It's gotta lock on it".
09-04-2007, 02:36 PM
#719
Just think for one second if GM did have a 500hp 100hp per liter Vette on the market.
How much hp improvement will you really make over the factory engine?
The #1 reason I am such an LS fan is because of the way these engines respond to mods. A 500 horse 5.0 liter that is already pooped out from the factory doesn't leave much on the table to add to like a 7.0 liter that makes 500 hp.
Think of all the 330hp M3's and 500hp M5 BMW's out there that have to do complete exhaust, cams, head work and more to achieve the gains you guys do from cat back and a tune.
How much hp improvement will you really make over the factory engine?
The #1 reason I am such an LS fan is because of the way these engines respond to mods. A 500 horse 5.0 liter that is already pooped out from the factory doesn't leave much on the table to add to like a 7.0 liter that makes 500 hp.
Think of all the 330hp M3's and 500hp M5 BMW's out there that have to do complete exhaust, cams, head work and more to achieve the gains you guys do from cat back and a tune.
09-04-2007, 09:00 PM
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Originally Posted by GSXRofDFW
Just think for one second if GM did have a 500hp 100hp per liter Vette on the market.
How much hp improvement will you really make over the factory engine?
The #1 reason I am such an LS fan is because of the way these engines respond to mods. A 500 horse 5.0 liter that is already pooped out from the factory doesn't leave much on the table to add to like a 7.0 liter that makes 500 hp.
Think of all the 330hp M3's and 500hp M5 BMW's out there that have to do complete exhaust, cams, head work and more to achieve the gains you guys do from cat back and a tune.
How much hp improvement will you really make over the factory engine?
The #1 reason I am such an LS fan is because of the way these engines respond to mods. A 500 horse 5.0 liter that is already pooped out from the factory doesn't leave much on the table to add to like a 7.0 liter that makes 500 hp.
Think of all the 330hp M3's and 500hp M5 BMW's out there that have to do complete exhaust, cams, head work and more to achieve the gains you guys do from cat back and a tune.