Ported 317s or stock L92 for 370" forged nitrous /carb build
03-17-2014, 03:09 PM
#22
I can prove that I can go faster than 9.87 in a car very comparable to Daves with more compression. I only have my heads milled .020 at the current time and am going to mill a touch more. I would be willing to bet a 9.90 currently and hopefully by years end it will go some 9.80s. I looked up his race weight and it was 2900. Mine was 2965, so I will soon have 68 lbs pulled out of mine, and .010 more milled from my heads. Current et with .020 off them is 6.34 in the 1/8 mile. It will be faster for sure this year. I am betting on 6 teens. But not rulling out 6.0s. I have a 4.30 gear going in now, but that isnt gonna help much. It would still go plenty fast with the current 4.10s. I am not taking nothing from Dave, but cam grinders are more knowledgeable now so I think faster is gonna come easier.
03-17-2014, 03:44 PM
#23
I can prove that I can go faster than 9.87 in a car very comparable to Daves with more compression. I only have my heads milled .020 at the current time and am going to mill a touch more. I would be willing to bet a 9.90 currently and hopefully by years end it will go some 9.80s. I looked up his race weight and it was 2900. Mine was 2965, so I will soon have 68 lbs pulled out of mine, and .010 more milled from my heads. Current et with .020 off them is 6.34 in the 1/8 mile. It will be faster for sure this year. I am betting on 6 teens. But not rulling out 6.0s. I have a 4.30 gear going in now, but that isnt gonna help much. It would still go plenty fast with the current 4.10s. I am not taking nothing from Dave, but cam grinders are more knowledgeable now so I think faster is gonna come easier.
03-17-2014, 04:50 PM
#25
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Because more compression makes N/A cars go faster. This is not a "trendy" idea or a flight of fancy, but merely a cornerstone of racing since, well, the beginning of racing.
This is a vague general statement, but in my opinion it is factually untrue.
The limitation of increased compression is the ability of your combination and choice of fuel to handle the operating pressures. And, if you do enough reading of shared results of people who have pushed the envelope of pump gas compression with LS engines, you will find many, many examples of people venturing into the 12:1 compression ratio territory successfully.
So, take whatever lower compression N/A combo that you want to use as an example, pump it up to 11.5:1 and watch it make more power everywhere. It isn't a theory, it is historical fact.
This is a vague general statement, but in my opinion it is factually untrue.
The limitation of increased compression is the ability of your combination and choice of fuel to handle the operating pressures. And, if you do enough reading of shared results of people who have pushed the envelope of pump gas compression with LS engines, you will find many, many examples of people venturing into the 12:1 compression ratio territory successfully.
So, take whatever lower compression N/A combo that you want to use as an example, pump it up to 11.5:1 and watch it make more power everywhere. It isn't a theory, it is historical fact.
But please do explain how when comparing Dave's low comp combo to Dogsballs high comp combo, the 7.6:1 dynamic vs the 9.1 dynamic has resulted in the lower compression engine combination to be making a good 50-60 more average HP based on weight/mph??
03-18-2014, 11:23 AM
#26
As for what you actually said, the answer is no. Static compression of any given motor has no relationship to the camshaft installed in the engine. An engine's static compression ratio remains the same no matter what camshaft is used. You can even remove the camshaft from the engine and that will not change the physical static compression ratio. The static compression ratio is simply a function of total swept area vs. total compressed area. The valvetrain is not part of the formula.
If what you were trying to say is that an engine's static compression ratio should be chosen in relationship to a racing engine valve events, then I would say yes, I agree completely. Picking the maximum practical static compression ratio for a given engine and its fuel's maximum efficiency will always contribute to maximum power output.
They are two different cars on opposite sides of the planet with different people assembling them, tuning them and with a myriad of different parts(transmissions, converters, rear ends, carburetors, ignitions, aerodynamics, weather, drivers, cam timing, lifter preload, oil viscosity, ring blow-by, valve sealing, etc.). This site itself has untold amounts of people running similar combinations with dramatically different results. How many threads are there on this site of guys saying: "I have the same parts as so and so does. Why is my car not making the numbers?" or "No way did you go that fast with those parts. You are hiding nitrous".
You just can't take two random individuals cars and come to a specific conclusion on one particular specification while ignoring all the other variables. that is not a-b testing. It is just speculation. I am not saying you can't speculate. We all do. But, you have to consider that there are far too many variables to consider that speculation to be valid data to base your theories on.
Dave is a smart guy, go ask Dave if he thinks his car would go faster with more compression. I think you will find he will say yes without a doubt.
03-18-2014, 11:53 AM
#27
I am not sure if I should speak to what you actually said, or perhaps what I think you meant to say. So, to be sure, I will speak to both.
As for what you actually said, the answer is no. Static compression of any given motor has no relationship to the camshaft installed in the engine. An engine's static compression ratio remains the same no matter what camshaft is used. You can even remove the camshaft from the engine and that will not change the physical static compression ratio. The static compression ratio is simply a function of total swept area vs. total compressed area. The valvetrain is not part of the formula.
If what you were trying to say is that an engine's static compression ratio should be chosen in relationship to a racing engine valve events, then I would say yes, I agree completely. Picking the maximum practical static compression ratio for a given engine and its fuel's maximum efficiency will always contribute to maximum power output.
If this is the basis for your postulation that lower compression makes more power, I would suggest that you consider the vast number of variables that you are assuming are equal or are ignoring completely in order to come to your conclusion.
They are two different cars on opposite sides of the planet with different people assembling them, tuning them and with a myriad of different parts(transmissions, converters, rear ends, carburetors, ignitions, aerodynamics, weather, drivers, cam timing, lifter preload, oil viscosity, ring blow-by, valve sealing, etc.). This site itself has untold amounts of people running similar combinations with dramatically different results. How many threads are there on this site of guys saying: "I have the same parts as so and so does. Why is my car not making the numbers?" or "No way did you go that fast with those parts. You are hiding nitrous".
You just can't take two random individuals cars and come to a specific conclusion on one particular specification while ignoring all the other variables. that is not a-b testing. It is just speculation. I am not saying you can't speculate. We all do. But, you have to consider that there are far too many variables to consider that speculation to be valid data to base your theories on.
Dave is a smart guy, go ask Dave if he thinks his car would go faster with more compression. I think you will find he will say yes without a doubt.
As for what you actually said, the answer is no. Static compression of any given motor has no relationship to the camshaft installed in the engine. An engine's static compression ratio remains the same no matter what camshaft is used. You can even remove the camshaft from the engine and that will not change the physical static compression ratio. The static compression ratio is simply a function of total swept area vs. total compressed area. The valvetrain is not part of the formula.
If what you were trying to say is that an engine's static compression ratio should be chosen in relationship to a racing engine valve events, then I would say yes, I agree completely. Picking the maximum practical static compression ratio for a given engine and its fuel's maximum efficiency will always contribute to maximum power output.
If this is the basis for your postulation that lower compression makes more power, I would suggest that you consider the vast number of variables that you are assuming are equal or are ignoring completely in order to come to your conclusion.
They are two different cars on opposite sides of the planet with different people assembling them, tuning them and with a myriad of different parts(transmissions, converters, rear ends, carburetors, ignitions, aerodynamics, weather, drivers, cam timing, lifter preload, oil viscosity, ring blow-by, valve sealing, etc.). This site itself has untold amounts of people running similar combinations with dramatically different results. How many threads are there on this site of guys saying: "I have the same parts as so and so does. Why is my car not making the numbers?" or "No way did you go that fast with those parts. You are hiding nitrous".
You just can't take two random individuals cars and come to a specific conclusion on one particular specification while ignoring all the other variables. that is not a-b testing. It is just speculation. I am not saying you can't speculate. We all do. But, you have to consider that there are far too many variables to consider that speculation to be valid data to base your theories on.
Dave is a smart guy, go ask Dave if he thinks his car would go faster with more compression. I think you will find he will say yes without a doubt.
03-18-2014, 04:19 PM
#28
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If what you were trying to say is that an engine's static compression ratio should be chosen in relationship to a racing engine valve events, then I would say yes, I agree completely. Picking the maximum practical static compression ratio for a given engine and its fuel's maximum efficiency will always contribute to maximum power output.
If this is the basis for your postulation that lower compression makes more power, I would suggest that you consider the vast number of variables that you are assuming are equal or are ignoring completely in order to come to your conclusion.
You just can't take two random individuals cars and come to a specific conclusion on one particular specification while ignoring all the other variables. that is not a-b testing. It is just speculation. I am not saying you can't speculate. We all do. But, you have to consider that there are far too many variables to consider that speculation to be valid data to base your theories on.
Dave is a smart guy, go ask Dave if he thinks his car would go faster with more compression. I think you will find he will say yes without a doubt.
If this is the basis for your postulation that lower compression makes more power, I would suggest that you consider the vast number of variables that you are assuming are equal or are ignoring completely in order to come to your conclusion.
You just can't take two random individuals cars and come to a specific conclusion on one particular specification while ignoring all the other variables. that is not a-b testing. It is just speculation. I am not saying you can't speculate. We all do. But, you have to consider that there are far too many variables to consider that speculation to be valid data to base your theories on.
Dave is a smart guy, go ask Dave if he thinks his car would go faster with more compression. I think you will find he will say yes without a doubt.
Secondly no, I am using it as purely an example of a car with excessive compression vs camshaft used, resulting in too high dynamic comp (my calculations are very conservative as well) and I am not going to divulge into the many things that this could be creating that result in a loss of power.
Dave is a smart guy, but there is no rocket science in the LQ4 combo, dogsballs car has run some decent mph and 60ft times so there is nothing to say that there is anything wrong with the car/driver or general setup, but at 300 odd pounds less weight, it is definitely making less HP than the 10:1 combo.
As fast89stang said, and I don't doubt it, that he should be able to beat Dave's LQ4 combo.. but it won't be achieved by running 9.1+ dynamic comp by creating excessively high static comp and pairing it with a relatively small camshaft.
03-18-2014, 11:16 PM
#29
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i still think compression is your friend
VLSL what are your thoughts on my previous combo in a heavy street car. similar 6.0 alloy block, stock flat tops with flycuts, same heads unported but with 100 thou off, so ~11.9:1, but with stock ls2 cam ,204/207 575/575 114 lsa, e85 but efi.
so a really small cam, but this made power to 7200 rpm, which it shouldn't have.
VLSL what are your thoughts on my previous combo in a heavy street car. similar 6.0 alloy block, stock flat tops with flycuts, same heads unported but with 100 thou off, so ~11.9:1, but with stock ls2 cam ,204/207 575/575 114 lsa, e85 but efi.
so a really small cam, but this made power to 7200 rpm, which it shouldn't have.
03-19-2014, 04:16 AM
#30
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Power to 7200 sure, but comparable to what exactly?
Having worked for a shop that did a lot of CNC work on LS heads, flow bench, dyno testing etc. I wouldn't have expected any sort of remarkable results, although I would imagine quite a bit of ignition timing would have had to have been pulled out. This combined with the cooling effect of E85 would have been the only thing saving an engine that would have been prone to detonation.
This is isn't the point though, yes compression is your friend in a well thought-out combo, where everything is designed to work together.
I have seen many examples where a lower compression combination will out perform a less than ideal high compression combo. And the same can be said about excessive camshaft selection, which can bleed off too much cylinder pressure/lessen dynamic compression.
Having worked for a shop that did a lot of CNC work on LS heads, flow bench, dyno testing etc. I wouldn't have expected any sort of remarkable results, although I would imagine quite a bit of ignition timing would have had to have been pulled out. This combined with the cooling effect of E85 would have been the only thing saving an engine that would have been prone to detonation.
This is isn't the point though, yes compression is your friend in a well thought-out combo, where everything is designed to work together.
I have seen many examples where a lower compression combination will out perform a less than ideal high compression combo. And the same can be said about excessive camshaft selection, which can bleed off too much cylinder pressure/lessen dynamic compression.
03-19-2014, 07:02 AM
#31
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not everyone can afford ported though.
not a huge fan of cnc heads, especially given the $$ to hp ratio. cathedral, yeah ok there is a case to be had, but square port heads are massive.
not a huge fan of cnc heads, especially given the $$ to hp ratio. cathedral, yeah ok there is a case to be had, but square port heads are massive.
03-19-2014, 05:42 PM
#33
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Not really the point, but keep in mind Australia has a lot of people in the industry who dont really deliver great results, mostly due to nothing more than their own lack of knowledge, and are only out there to fill their pockets.
03-19-2014, 06:30 PM
#35
What the hell is going on in this thread? V insults the entire head porting industry in Australia then Zane comes in and says: "There is nearly no physical labor to the hand ported head". Did I come back from vacation to an alternate carb forum universe?
03-19-2014, 07:30 PM
#36
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Now, not to throw gas on a fire. I have copied Dave's old combo and didn't have the greatest results....yet.
Yes my car is about 500# heavier, but I shaved the heads for a little more compression to "help" off-set that....maybe ?
What I don't know is if he advance the cam to create more cylinder pressure or ????
As for motor "copies".... GM builds thousands of motors every year and rate them the same as each other (LQ4 is XXX, LY6 is XXX, LQ9 is XXX, ETC.).... so why couldn't someone build a "copy" and expect the same or similar performance of the one they copied ? Raced at same track even. You would think they'd be closer (Full second slower
)
I'm sure there are "tricks" done or maybe even a "secret" cam and it's even possible that someone's not telling the full truth.
Yes my car is about 500# heavier, but I shaved the heads for a little more compression to "help" off-set that....maybe ?
What I don't know is if he advance the cam to create more cylinder pressure or ????
As for motor "copies".... GM builds thousands of motors every year and rate them the same as each other (LQ4 is XXX, LY6 is XXX, LQ9 is XXX, ETC.).... so why couldn't someone build a "copy" and expect the same or similar performance of the one they copied ? Raced at same track even. You would think they'd be closer (Full second slower
)I'm sure there are "tricks" done or maybe even a "secret" cam and it's even possible that someone's not telling the full truth.
03-19-2014, 07:40 PM
#37
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Haha, hold up a minute! While there is a handful of reputable cylinder head cnc operators in Australia, there is an enormity of mimics, and even when you do get a good operator you pay a small fortune for there work.
03-19-2014, 08:29 PM
#38
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i think it even covers the states as well, however they have the cathedral heads dialled. square port i think there is still a lot to learn, but saying that the big hp guys go to LS7 or big high port heads. but as time goes by and people more to the square ports from the cathedral things will change.
i don't think there are necessarily any secrets to dave's 6.0 combo, it just worked and combined with a well set-up (1.35 60ft) and relatively light car, it ran well. if i had more time to tweak my car i could of got a 9.8, but i'm overseas now for a bit.