Tech Question on Cams
Thread Starter
Burning Brakes
Joined: Jun 2012
Posts: 1,240
Likes: 1
From: Orange County California
Tech Question on Cams
So I'm looking to get as much low and midrange torque out of a heads/cam combo that I can get.
Understanding that Torque is a function of Velocity of airflow, not just total volume of airflow, I've decided on something like the AFR 205 cc heads, they have the same volume as stock but flow 70 cfm faster than stock. They are small port high flow velocity heads that should generate great torque improvements. I will also mill the heads to get as much compression as I can with the cam I choose, without having to flycut the pistons or use race fuel. I figure the higher compression should help increase overall useable torque as well.
My question is this:
If I want to get as much usable torque as possible with these heads by selecting cam specs that will increase the "velocity" of airflow, I can't figure out if I should be going with a lower duration amd higher lift, like a 224/228 with something like 595/595 lift
or
longer duration lower lift cam specs like a 236/240 at around 560/570 lift
what will make faster gas flow velocity through the heads I picked?
Or should I be thinking about something else entirely regarding the cam and mid RPM torque
Understanding that Torque is a function of Velocity of airflow, not just total volume of airflow, I've decided on something like the AFR 205 cc heads, they have the same volume as stock but flow 70 cfm faster than stock. They are small port high flow velocity heads that should generate great torque improvements. I will also mill the heads to get as much compression as I can with the cam I choose, without having to flycut the pistons or use race fuel. I figure the higher compression should help increase overall useable torque as well.
My question is this:
If I want to get as much usable torque as possible with these heads by selecting cam specs that will increase the "velocity" of airflow, I can't figure out if I should be going with a lower duration amd higher lift, like a 224/228 with something like 595/595 lift
or
longer duration lower lift cam specs like a 236/240 at around 560/570 lift
what will make faster gas flow velocity through the heads I picked?
Or should I be thinking about something else entirely regarding the cam and mid RPM torque
Last edited by steven31371; Feb 8, 2013 at 09:12 PM.
Racer
Joined: Aug 2006
Posts: 258
Likes: 0
From: Tulsa Oklahoma
Read these threads. There is a ton of good info in them.
http://ls1tech.com/forums/generation...am-change.html
http://ls1tech.com/forums/generation...heads-cam.html
http://ls1tech.com/forums/generation...am-change.html
http://ls1tech.com/forums/generation...heads-cam.html
Safety Car
Joined: Aug 2011
Posts: 4,439
Likes: 405
From: Portland OR
Long duration moves the torque curve higher. You would like the smaller cam you chose. Better yet, let EPS design you a custom. They will put the power where you want it. The AFR heads will extend the rpm range of even a small cam.
Safety Car
Joined: Oct 2004
Posts: 4,816
Likes: 132
From: Plano TX
So I'm looking to get as much low and midrange torque out of a heads/cam combo that I can get.
Understanding that Torque is a function of Velocity of airflow, not just total volume of airflow, I've decided on something like the AFR 205 cc heads, they have the same volume as stock but flow 70 cfm faster than stock. They are small port high flow velocity heads that should generate great torque improvements. I will also mill the heads to get as much compression as I can with the cam I choose, without having to flycut the pistons or use race fuel. I figure the higher compression should help increase overall useable torque as well.
My question is this:
If I want to get as much usable torque as possible with these heads by selecting cam specs that will increase the "velocity" of airflow, I can't figure out if I should be going with a lower duration amd higher lift, like a 224/228 with something like 595/595 lift
or
longer duration lower lift cam specs like a 236/240 at around 560/570 lift
what will make faster gas flow velocity through the heads I picked?
Or should I be thinking about something else entirely regarding the cam and mid RPM torque
Understanding that Torque is a function of Velocity of airflow, not just total volume of airflow, I've decided on something like the AFR 205 cc heads, they have the same volume as stock but flow 70 cfm faster than stock. They are small port high flow velocity heads that should generate great torque improvements. I will also mill the heads to get as much compression as I can with the cam I choose, without having to flycut the pistons or use race fuel. I figure the higher compression should help increase overall useable torque as well.
My question is this:
If I want to get as much usable torque as possible with these heads by selecting cam specs that will increase the "velocity" of airflow, I can't figure out if I should be going with a lower duration amd higher lift, like a 224/228 with something like 595/595 lift
or
longer duration lower lift cam specs like a 236/240 at around 560/570 lift
what will make faster gas flow velocity through the heads I picked?
Or should I be thinking about something else entirely regarding the cam and mid RPM torque
Thread Starter
Burning Brakes
Joined: Jun 2012
Posts: 1,240
Likes: 1
From: Orange County California
The 224/228 is a great grind for what you are looking for, with a .595ish lift on both sides.. The milling of the heads will increase compression and low end torque.. A 114-115 lobe seperation will spread out the power curve.. I spent many hours looking at cam profiles, Head porting and milling and exhaust, set ups from 1-3/4 Longtube Headers to 1-7/8 Headers.. I wanted low and mid range torque, as well as streetable manners for city driving.. I wound up choosing a 1-3/4 long tube over a 1-7/8 inch.. I also went with a bigger 230/234 cam in the low .600 lift range on a 114+4 lobe.. I'm very happy with that set up.. That is on the large size of a small cam,as far as I am concerned. I'd rather have streetable low and mid range torque, under the curve, rather than another 15-20 rwhp at the top end. You will get 100 opinions on different set ups, and it can drive you crazy reading all the different posts.. Check out LG's G5X1e cam.. 226/230 ish duration with high .580-.590ish lift on a 114 or 115 lobe.. Good luck!
Thanks
Thread Starter
Burning Brakes
Joined: Jun 2012
Posts: 1,240
Likes: 1
From: Orange County California
Got it, thanks....am just trying to learn as much as I can for right now.
Thread Starter
Burning Brakes
Joined: Jun 2012
Posts: 1,240
Likes: 1
From: Orange County California
Read these threads. There is a ton of good info in them.
http://ls1tech.com/forums/generation...am-change.html
http://ls1tech.com/forums/generation...heads-cam.html
http://ls1tech.com/forums/generation...am-change.html
http://ls1tech.com/forums/generation...heads-cam.html
Hey thanks for the links!....very good threads, very informative
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Safety Car
Joined: Aug 2011
Posts: 4,439
Likes: 405
From: Portland OR
Safety Car
Joined: Oct 2004
Posts: 4,816
Likes: 132
From: Plano TX
I had LLoyd Elliot in Dallas port polish and mill my stock 243 Heads to 62cc, as well as a 3angle valve job, for $600.. The tune is conservative and there as another 10-15 horsepower on the table.. The problem is that my stock 28 lb injectors are right at 100% on the duty cycle.. I'll be putting in some 34 lb LS2 injectors in the near future.. I'll post a flow chart on my heads
Last edited by David426; Feb 9, 2013 at 12:04 PM.
Safety Car
Joined: Oct 2004
Posts: 4,816
Likes: 132
From: Plano TX
These are the numbers after porting my stock heads. I picked up 20% @.600 lift on the intake side and 15% on the exhaust side. Stock LS6 heads flow 250 cfm on the intake side at .600 lift and 180 cfm on the exhaust side.. CNC Heads will flow a little more but you will pay a heck of a lot more money too.. I'm happy for the $600 I spent The cylinder heads were also milled down to 62mm, which brings compression ratio up to 10.9:1 (more low end torque,, yee haww)
Last edited by David426; Feb 9, 2013 at 12:05 PM.
Thread Starter
Burning Brakes
Joined: Jun 2012
Posts: 1,240
Likes: 1
From: Orange County California
These are the numbers after porting my stock heads. I picked up 20% @.600 lift on the intake side and 15% on the exhaust side. Stock LS6 heads flow 250 cfm on the intake side at .600 lift and 180 cfm on the exhaust side.. CNC Heads will flow a little more but you will pay a heck of a lot more money too.. I'm happy for the $600 I spent The cylinder heads were also milled down to 62mm, which brings compression ratio up to 10.9:1 (more low end torque,, yee haww)
Safety Car
Joined: Aug 2011
Posts: 4,439
Likes: 405
From: Portland OR
David, very good bang for the buck on the head work! The hp numbers back it up. I assume a 6 speed trans.
What cam are you using with that? Intake? TB? MAF?
I am right at 90% duty cycle on the LS2 injectors. They are taller, and have a diff connector, I'm sure you know that.
Had it down the 1/4 mile?
Ron
What cam are you using with that? Intake? TB? MAF?
I am right at 90% duty cycle on the LS2 injectors. They are taller, and have a diff connector, I'm sure you know that.
Had it down the 1/4 mile?
Ron
Thread Starter
Burning Brakes
Joined: Jun 2012
Posts: 1,240
Likes: 1
From: Orange County California
David, very good bang for the buck on the head work! The hp numbers back it up. I assume a 6 speed trans.
What cam are you using with that? Intake? TB? MAF?
I am right at 90% duty cycle on the LS2 injectors. They are taller, and have a diff connector, I'm sure you know that.
Had it down the 1/4 mile?
Ron
What cam are you using with that? Intake? TB? MAF?
I am right at 90% duty cycle on the LS2 injectors. They are taller, and have a diff connector, I'm sure you know that.
Had it down the 1/4 mile?
Ron
Seems like really good bang for the buck!
Safety Car
Joined: Oct 2004
Posts: 4,816
Likes: 132
From: Plano TX
David, very good bang for the buck on the head work! The hp numbers back it up. I assume a 6 speed trans.
What cam are you using with that? Intake? TB? MAF?
I am right at 90% duty cycle on the LS2 injectors. They are taller, and have a diff connector, I'm sure you know that.
Had it down the 1/4 mile?
Ron
What cam are you using with that? Intake? TB? MAF?
I am right at 90% duty cycle on the LS2 injectors. They are taller, and have a diff connector, I'm sure you know that.
Had it down the 1/4 mile?
Ron
Last edited by David426; Feb 9, 2013 at 03:59 PM.
Safety Car
Joined: Oct 2004
Posts: 4,816
Likes: 132
From: Plano TX
The Heads were put on a flow bench after all the port work was done,, The heads were later milled and de-burred .. So these numbers are before milling... Great Bang for the buck.. Lloyd Elliott does great work.. He has a Machine shop in his backyard and has been porting Heads and intakes for over 20 years, Thats all he does.. He mainly does LS Heads and older LT Heads.. He has a great reputation,, low overhead, quality work and a great price.. I could have had more chamber work done and had the Heads CNC;d but I would be paying double for just a little more airflow
Last edited by David426; Feb 9, 2013 at 04:08 PM.