230/236 114+4 cam questions
09-02-2014, 10:43 PM
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230/236 114+4 cam questions The cam is from Tooley, it's his btr stage 3 turbo.
They recommended the cam for a 32x" rod/piston twin s366 motor. It's in a stock 5.3 while I build the motor and turbo setup. My problem is I'm feeling cheap lately. Any issues using this cam in a small inch rod/piston motor, Holley Hiram, th400/ptc 3500 with a single Borg turbo instead of the twins? Looking for enough power to push 3500 lbs sub 8.50.
They recommended the cam for a 32x" rod/piston twin s366 motor. It's in a stock 5.3 while I build the motor and turbo setup. My problem is I'm feeling cheap lately. Any issues using this cam in a small inch rod/piston motor, Holley Hiram, th400/ptc 3500 with a single Borg turbo instead of the twins? Looking for enough power to push 3500 lbs sub 8.50.
09-03-2014, 02:00 AM
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Would a person be better off saving pennies for a few more months, in your opinion, and stick with the original plan? I have a tig so the only extra cost will be the extra turbo, oil feed/return and an extra waste gate. So around 1k more. Honestly by the time I pony up for something bigger or billet to get where I want to be, the price looks like it might be comparable.... Am I right, or close? That and figure a restall as well. Need this to stall on the footbrake, no trans brake. Looks like I might just stick with the original plan lol
09-06-2014, 05:42 PM
#4
Cam seems large for a 320 c.i. motor.
I used to like to cam engines to make as much power on as little boost as possible. Large cams accomplish this because they raise VE% of the engine N/A which in turn moves more airflow. This makes more power on less boost pressure, but the amount of airflow being moved is the same as a smaller cam and higher boost pressure.
On low boost this is not an issue as the compressor map is wide enough to keep the turbo in an efficiency island that is still optimal. At higher boost though where the compressor map gets narrower, a cam this large being used in your combo with that turbo will put the compressor wheel well outside of its efficiency islands and back pressure rises as a result.
Keeping the cam smaller and boost pressure higher lowers the boost pressure to back pressure ratio. Since the smaller cam will move less airflow on the same amount of boost as the large cam, more boost pressure is needed to move the same amount of airflow. This helps keep compressor efficiency higher which means lower IAT's, lower back pressure and more power across the RPM range.
Lower back pressure will allow power to peak higher and will allow the engine to pull further into the RPM range. Smaller cams will also move more airflow at lower engine speeds which builds boost faster if the turbo is capable of doing so.
Yes you will have to run more boost with a smaller cam than you would with a larger cam, but it does not mean that the engine will blow up sooner, or lift the heads sooner. Boost is just a number and is not a direct indication of cylinder pressure.
I used to like to cam engines to make as much power on as little boost as possible. Large cams accomplish this because they raise VE% of the engine N/A which in turn moves more airflow. This makes more power on less boost pressure, but the amount of airflow being moved is the same as a smaller cam and higher boost pressure.
On low boost this is not an issue as the compressor map is wide enough to keep the turbo in an efficiency island that is still optimal. At higher boost though where the compressor map gets narrower, a cam this large being used in your combo with that turbo will put the compressor wheel well outside of its efficiency islands and back pressure rises as a result.
Keeping the cam smaller and boost pressure higher lowers the boost pressure to back pressure ratio. Since the smaller cam will move less airflow on the same amount of boost as the large cam, more boost pressure is needed to move the same amount of airflow. This helps keep compressor efficiency higher which means lower IAT's, lower back pressure and more power across the RPM range.
Lower back pressure will allow power to peak higher and will allow the engine to pull further into the RPM range. Smaller cams will also move more airflow at lower engine speeds which builds boost faster if the turbo is capable of doing so.
Yes you will have to run more boost with a smaller cam than you would with a larger cam, but it does not mean that the engine will blow up sooner, or lift the heads sooner. Boost is just a number and is not a direct indication of cylinder pressure.
09-06-2014, 06:37 PM
#5
Cam seems large for a 320 c.i. motor.
I used to like to cam engines to make as much power on as little boost as possible. Large cams accomplish this because they raise VE% of the engine N/A which in turn moves more airflow. This makes more power on less boost pressure, but the amount of airflow being moved is the same as a smaller cam and higher boost pressure.
On low boost this is not an issue as the compressor map is wide enough to keep the turbo in an efficiency island that is still optimal. At higher boost though where the compressor map gets narrower, a cam this large being used in your combo with that turbo will put the compressor wheel well outside of its efficiency islands and back pressure rises as a result.
Keeping the cam smaller and boost pressure higher lowers the boost pressure to back pressure ratio. Since the smaller cam will move less airflow on the same amount of boost as the large cam, more boost pressure is needed to move the same amount of airflow. This helps keep compressor efficiency higher which means lower IAT's, lower back pressure and more power across the RPM range.
Lower back pressure will allow power to peak higher and will allow the engine to pull further into the RPM range. Smaller cams will also move more airflow at lower engine speeds which builds boost faster if the turbo is capable of doing so.
Yes you will have to run more boost with a smaller cam than you would with a larger cam, but it does not mean that the engine will blow up sooner, or lift the heads sooner. Boost is just a number and is not a direct indication of cylinder pressure.
I used to like to cam engines to make as much power on as little boost as possible. Large cams accomplish this because they raise VE% of the engine N/A which in turn moves more airflow. This makes more power on less boost pressure, but the amount of airflow being moved is the same as a smaller cam and higher boost pressure.
On low boost this is not an issue as the compressor map is wide enough to keep the turbo in an efficiency island that is still optimal. At higher boost though where the compressor map gets narrower, a cam this large being used in your combo with that turbo will put the compressor wheel well outside of its efficiency islands and back pressure rises as a result.
Keeping the cam smaller and boost pressure higher lowers the boost pressure to back pressure ratio. Since the smaller cam will move less airflow on the same amount of boost as the large cam, more boost pressure is needed to move the same amount of airflow. This helps keep compressor efficiency higher which means lower IAT's, lower back pressure and more power across the RPM range.
Lower back pressure will allow power to peak higher and will allow the engine to pull further into the RPM range. Smaller cams will also move more airflow at lower engine speeds which builds boost faster if the turbo is capable of doing so.
Yes you will have to run more boost with a smaller cam than you would with a larger cam, but it does not mean that the engine will blow up sooner, or lift the heads sooner. Boost is just a number and is not a direct indication of cylinder pressure.
09-08-2014, 06:51 AM
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Makes since. We'll see how it does tho, BTR has been in the game for a while and was recommended to me by a well respected local tuner. Just gonna pinch pennies an go ahead with the twins... The wife has my Christmas list lol