J-Spec NA build
04-02-2007, 07:28 AM
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Originally Posted by Sk8fe
So the Cosworth's combustion chamber will look like the stock VQ's chamber and not like the NISMO's?
04-02-2007, 11:27 AM
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Yeah, from what i have seen they are their own design. What i am curious about is to wether or not getting new high comp pistons would gain any HP in NA cars. If high comp heads gain power, then i would assume High comp pistons do also. Any info on this would be nice, along w/ around how much you can expect to pick up if you have only some minor bolt ons and a tune
04-02-2007, 11:32 AM
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Originally Posted by Sk8fe
Sorry, I'm confused. So Cosworth's combustion chamber doesn't look like the NISMO's and it doesn't look like stock, so they cast their complete own VQ head?
04-02-2007, 05:50 PM
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^^^ +1
but how about until 91 isn't enough. we don't have 93 hear the next up is 101 i think and i only know of one gas station the is semi close who has it (about 10 miles)
but how about until 91 isn't enough. we don't have 93 hear the next up is 101 i think and i only know of one gas station the is semi close who has it (about 10 miles)
04-02-2007, 05:51 PM
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Originally Posted by scratch137
What i am curious about is to wether or not getting new high comp pistons would gain any HP in NA cars. If high comp heads gain power, then i would assume High comp pistons do also. Any info on this would be nice, along w/ around how much you can expect to pick up if you have only some minor bolt ons and a tune
04-03-2007, 05:15 AM
#71
of course it would pick up power...you would pick up more torque then hp and torque is what moves your car..as far as how much you can raise it on pump gas, I have no experience with that with a VQ. Honda's run 11.5 all day, but I think they have a more effiecient combustion chamber to do so.
04-03-2007, 05:27 AM
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Cosworth starts with stock VQ35 heads, and CNC's them to their own specs. The result is the combustion chamber changes in design and this is what causes the drop in compression vs std. VQ35 heads.
The NISMO heads are a completely different casting from the std VQ35.
The short answer is, there is no "magic" compression number that is "safe" or "not safe".
Many factory cars run higher compression than the Z, but it's a function of internal design and not merely a static CR #. Sort of like when saying "my car runs 20 psi of boost". As we all know - boost in and of itself is a useless #, since 20 psi on a turbo like a K03 (stock on VW and Audi's) is alot different than 20 psi on a GT30R and so on.
Compression is very much the same - 11.5:1 on one car is not the same as 11.5:1 on another, as combustion chamber design, piston design, etc all play a major role. Alot of people get all hung up on compression as if it actually tells you something - it really does not. People will say "well, a GT3 runs 12:1 and runs on 91 octane, the Audi 2.0Turbo FSI motors run 10.5 and are turbo cars, an 06 + Civic Si runs 11:1, etc" - all of it is completely inconsequential as it relates to a VQ, unless these motors have similar combustion chamber, fuel system specs, and piston designs (among other things). Besides that, it's merely a number that is only relative to other VQ's.
Compression and state of tune go hand in hand. The trick is finding that happy medium between a safe tune and a higher-than-stock compression ratio. As you increase your static compression, your margin for error on the tuning side of things goes down. The ONLY way to find that medium is trial and error.
This is why when embarking on an NA build, you need to have the experience of a good machinist behind you, as well as a good tuner, and the willingness to spend the $ and try different setups (or the upfront money to do it the proper way the first time). No matter how you slice it. Without these three ingredients, you're sure to fall short of what the cars potential actually could be.
The NISMO heads are a completely different casting from the std VQ35.
The short answer is, there is no "magic" compression number that is "safe" or "not safe".
Many factory cars run higher compression than the Z, but it's a function of internal design and not merely a static CR #. Sort of like when saying "my car runs 20 psi of boost". As we all know - boost in and of itself is a useless #, since 20 psi on a turbo like a K03 (stock on VW and Audi's) is alot different than 20 psi on a GT30R and so on.
Compression is very much the same - 11.5:1 on one car is not the same as 11.5:1 on another, as combustion chamber design, piston design, etc all play a major role. Alot of people get all hung up on compression as if it actually tells you something - it really does not. People will say "well, a GT3 runs 12:1 and runs on 91 octane, the Audi 2.0Turbo FSI motors run 10.5 and are turbo cars, an 06 + Civic Si runs 11:1, etc" - all of it is completely inconsequential as it relates to a VQ, unless these motors have similar combustion chamber, fuel system specs, and piston designs (among other things). Besides that, it's merely a number that is only relative to other VQ's.
Compression and state of tune go hand in hand. The trick is finding that happy medium between a safe tune and a higher-than-stock compression ratio. As you increase your static compression, your margin for error on the tuning side of things goes down. The ONLY way to find that medium is trial and error.
This is why when embarking on an NA build, you need to have the experience of a good machinist behind you, as well as a good tuner, and the willingness to spend the $ and try different setups (or the upfront money to do it the proper way the first time). No matter how you slice it. Without these three ingredients, you're sure to fall short of what the cars potential actually could be.
Last edited by Z1 Performance; 04-03-2007 at 05:31 AM.
My fiance has a passat. Looking at the k04 upgrade...
04-03-2007, 09:26 AM
#75
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Originally Posted by Z1 Performance
Cosworth starts with stock VQ35 heads, and CNC's them to their own specs. The result is the combustion chamber changes in design and this is what causes the drop in compression vs std. VQ35 heads.
The NISMO heads are a completely different casting from the std VQ35.
The short answer is, there is no "magic" compression number that is "safe" or "not safe".
Many factory cars run higher compression than the Z, but it's a function of internal design and not merely a static CR #. Sort of like when saying "my car runs 20 psi of boost". As we all know - boost in and of itself is a useless #, since 20 psi on a turbo like a K03 (stock on VW and Audi's) is alot different than 20 psi on a GT30R and so on.
Compression is very much the same - 11.5:1 on one car is not the same as 11.5:1 on another, as combustion chamber design, piston design, etc all play a major role. Alot of people get all hung up on compression as if it actually tells you something - it really does not. People will say "well, a GT3 runs 12:1 and runs on 91 octane, the Audi 2.0Turbo FSI motors run 10.5 and are turbo cars, an 06 + Civic Si runs 11:1, etc" - all of it is completely inconsequential as it relates to a VQ, unless these motors have similar combustion chamber, fuel system specs, and piston designs (among other things). Besides that, it's merely a number that is only relative to other VQ's.
Compression and state of tune go hand in hand. The trick is finding that happy medium between a safe tune and a higher-than-stock compression ratio. As you increase your static compression, your margin for error on the tuning side of things goes down. The ONLY way to find that medium is trial and error.
This is why when embarking on an NA build, you need to have the experience of a good machinist behind you, as well as a good tuner, and the willingness to spend the $ and try different setups (or the upfront money to do it the proper way the first time). No matter how you slice it. Without these three ingredients, you're sure to fall short of what the cars potential actually could be.
The NISMO heads are a completely different casting from the std VQ35.
The short answer is, there is no "magic" compression number that is "safe" or "not safe".
Many factory cars run higher compression than the Z, but it's a function of internal design and not merely a static CR #. Sort of like when saying "my car runs 20 psi of boost". As we all know - boost in and of itself is a useless #, since 20 psi on a turbo like a K03 (stock on VW and Audi's) is alot different than 20 psi on a GT30R and so on.
Compression is very much the same - 11.5:1 on one car is not the same as 11.5:1 on another, as combustion chamber design, piston design, etc all play a major role. Alot of people get all hung up on compression as if it actually tells you something - it really does not. People will say "well, a GT3 runs 12:1 and runs on 91 octane, the Audi 2.0Turbo FSI motors run 10.5 and are turbo cars, an 06 + Civic Si runs 11:1, etc" - all of it is completely inconsequential as it relates to a VQ, unless these motors have similar combustion chamber, fuel system specs, and piston designs (among other things). Besides that, it's merely a number that is only relative to other VQ's.
Compression and state of tune go hand in hand. The trick is finding that happy medium between a safe tune and a higher-than-stock compression ratio. As you increase your static compression, your margin for error on the tuning side of things goes down. The ONLY way to find that medium is trial and error.
This is why when embarking on an NA build, you need to have the experience of a good machinist behind you, as well as a good tuner, and the willingness to spend the $ and try different setups (or the upfront money to do it the proper way the first time). No matter how you slice it. Without these three ingredients, you're sure to fall short of what the cars potential actually could be.
Beautifully said. Well done man.
04-04-2007, 06:59 PM
#78
I stumbled on a good thread! The more and more info I get on N/A builds the more and more I just want to plan F/I street Kit or just do bolt ons and tune!! N/A is a venture for people that have more cash flow and more time to solve problems. Thanks for the Info!
04-05-2007, 10:07 AM
#80
Originally Posted by Z1 Performance
1. going for 400 whp and coming close to achieving it are 2 completely different things
2. every car you see that is remotely close (highest right now is in the 350-360 range on a Dynapack) are running compression from 13 to 13.5:1
3. they have virtually unlimited budgets
NA costs $, period, to do so in a reliable fashion.
2. every car you see that is remotely close (highest right now is in the 350-360 range on a Dynapack) are running compression from 13 to 13.5:1
3. they have virtually unlimited budgets
NA costs $, period, to do so in a reliable fashion.