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Discussion Starter #1
OK, let me TRY and make sense of what I mean to ask...lol...

Assume I have a car that is tuned great for say 15psi as far as no missing...runs smooth...has a great A/F curve...runs and drives excellent being tuned by standalone. Now that the car runs great, I want to tune/tweak the cam gears as best possible. I will be running a VERY large turbo, so one of my main objectives is tweaking to reduce lag, to get that turbo responding quicker, but hopefully w/o losing any top end.

I have two questions.

1) If I tweak the gears for optimal performance at 15 psi, will these settings still be optimal at 30-35psi, or will the change in airflow at high boost require different settings? I would love to be able to keep the boost cranked way down to do pull after pull on different cam gear settings vs pull after pull at 30-35 psi, if the settings will be the same for both.

2) I am running the AEM. I know it has excellent datalogging features. I need to find out if it has the ability to take the logged data and input it into a graph form such as one that looks like a dyno graph. And even if not, what would be the BEST info to log and how should I log, to find out if the turbo is reacting any faster or falling off up top? I have seen many arguements about the best method to use, such as graphing boost vs time, boost vs RPM, time vs RPM, boost vs speed, time vs RPM...etc...etc...Just wondering how you guys would graph it to find out if the turbo is reponding/building boost as fast as possible, but at the same time, not sacrificing much up top?

Thanks for any info you guys can provide! Take care!
 

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ALso remember if you adjust teh intake cam you must re sync your timing to the AEM.
 

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Discussion Starter #4
RickyB said:
Adjusting cams affects VE which requires tuning adjustments to maintain the same AFR
Thanks for responding, as I was looking forward to your input! I kinda figured that I would need to tweak the settings a little to maintain the right air fuel mixture. But taking that into account, and assuming that I made all the proper adjustments to get the best spoolup and power out of my setup at 15psi, including getting the fuel mixture back to perfect after the cam gear changes, will these 'tuned for 15psi' cam settings be the same settings that would be required at 30-35psi?
Celi GT4 said:
ALso remember if you adjust teh intake cam you must re sync your timing to the AEM.
I will not be the one initially tuning the car. That will be done by NoShoes, but please explain this a little more (re-sync'ing the timing??), just so I can understand it better. Sorry for the lack of insight, but thats why I am letting the true tuners handle it... :thumbup
 
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I did not try, but from theoretical view I think you get the best charge with keeping the intake valve open as long as possible and closing it just before the up movement of the piston starts to press the mixture out again. With higher boost I think the optimal angle to close the intake valve is some degrees later.
Reducing overlap on higher boost levels can be an issue too.
 
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You can get a sneaky-pete nitrous setup, something small just to spool the turbo. Thats what i understand a lot of guys with T78's and larger are doing.
 

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When you change your boost from 15psi to 30 it is going to have a serious effect on how much timing you are going to be able to run. It will also change how fast combustion occurs, which will then have an effect on when your valves should be opening and closing.

That is the end of my theory. What I can't tell you is how big that difference is.
 

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Discussion Starter #10
Thanks everyone, that is some of the info I was expecting, but not what I was hoping for... :shakeshea ....I was hoping that I could keep the same settings and be optimized across the whole boost range...oh well!

PS - I REALLY dont want to resort to nitrous if at all possible... :smile:
 

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ndisgii said:
I will not be the one initially tuning the car. That will be done by NoShoes, but please explain this a little more (re-sync'ing the timing??), just so I can understand it better. Sorry for the lack of insight, but thats why I am letting the true tuners handle it... :thumbup
Unlike the 2JZ-GTE that you are more familiar with, when you set your ignition timing on a 3S-GTE, you usually rotate your distributor. The distributor also has a cam angle sensor on the inside of the housing, behind the rotor cap. This cam angle sensor interpolates what your crank position is based on our intake cam's position. Because of our timing belt the camshafts are turning 2 times for every crank rotation.

Now, when you adjust your intake cam, you change the reading that our cam angle sensor is picking up. Normally, you would have to move the distributor again, but you have an aftermarket engine management system. In most EMSs, you can re-synchcronize the cam angle sensor in the software, instead of doing the tedious task of moving the distributor.

Back to the original query of the thread;

Remember that boost is just resistance to airflow. Making a great torque curve at both low boost compared to high boost usually depends on the overall VE of your motor. Typically, you'll see minimal changes in spool, and less and less torque at higher rpms at the higher boost ranges (where your setup begins to run out of flow).

Changing cam timing for high and low boost is not something that is usually discussed or done in practice. If one wants better spool, they can get a smaller turbocharger, and do everything they can to "choke" the motor in between the outlet of the compressor down to turbine inlet. Buying a V6, performing a swap, and installing a supercharger is typically the best way to improve low end torque.
 

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Discussion Starter #12
NoShoes said:
Unlike the 2JZ-GTE that you are more familiar with, when you set your ignition timing on a 3S-GTE, you usually rotate your distributor. The distributor also has a cam angle sensor on the inside of the housing, behind the rotor cap. This cam angle sensor interpolates what your crank position is based on our intake cam's position. Because of our timing belt the camshafts are turning 2 times for every crank rotation.

Now, when you adjust your intake cam, you change the reading that our cam angle sensor is picking up. Normally, you would have to move the distributor again, but you have an aftermarket engine management system. In most EMSs, you can re-synchcronize the cam angle sensor in the software, instead of doing the tedious task of moving the distributor.

Back to the original query of the thread;

Remember that boost is just resistance to airflow. Making a great torque curve at both low boost compared to high boost usually depends on the overall VE of your motor. Typically, you'll see minimal changes in spool, and less and less torque at higher rpms at the higher boost ranges (where your setup begins to run out of flow).

Changing cam timing for high and low boost is not something that is usually discussed or done in practice. If one wants better spool, they can get a smaller turbocharger, and do everything they can to "choke" the motor in between the outlet of the compressor down to turbine inlet. Buying a V6, performing a swap, and installing a supercharger is typically the best way to improve low end torque.
Thank you for the input! I am just thinking that I would rather have it optimized/maximized for my street tune at say 15-17 psi for the best possible curve I can achieve for this turbo. It will be at these settings 90% of the time since I dont plan on racing it regularly. Therefore, I am hoping that those settings wont choke me too bad once the boost gets turned up on occasion. Thanks man and take care!
 

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NoShoes said:
Unlike the 2JZ-GTE that you are more familiar with, when you set your ignition timing on a 3S-GTE, you usually rotate your distributor. The distributor also has a cam angle sensor on the inside of the housing, behind the rotor cap. This cam angle sensor interpolates what your crank position is based on our intake cam's position. Because of our timing belt the camshafts are turning 2 times for every crank rotation.

Now, when you adjust your intake cam, you change the reading that our cam angle sensor is picking up. Normally, you would have to move the distributor again, but you have an aftermarket engine management system. In most EMSs, you can re-synchcronize the cam angle sensor in the software, instead of doing the tedious task of moving the distributor.
that is very interesting to know....so when adjusting cam gears, if you adjust the exhaust cam it doesn't effect timing, but if you adjust the intake cam then you are making an adjustment also to the timing, right?? i assume if you don't have a stand alone then the only way to correct the timing being off is to rotate the distributor or just not to adjust the intake cam at all- is this right?
 
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