Can you replace a big CAM with a stock CAM
Thread Starter
Teching In
Joined: Nov 2011
Posts: 26
Likes: 5
From: Denver, CO
Can you replace a big CAM with a stock CAM I am looking to lower the power (yes not typical) in a LH6. The CAM spec's are 223/231 at .050 in .610/.617 lift with 112 LSA.The current CAM has output of 475HP/435TQ. (https://www.speedwaymotors.com/LS-Crate-Engine-Chevy-LH6-5-3L-475HP-435TQ,497805.html ). This engine has upgraded valve springs as well.
I am thinking of something like 190/191 at .050 in, .457/.466 and 115.5 LSA (Similar to a stock LM7). I'm very open to what CAM, but will be mindful of cost. The current CAM is too much power for my application, an airplane. I need ~300 hp @ 4500 RPM and I won't run the RPM any higher than 4500. I don't know, but googling the CAM specs leads me to CompCams ( https://www.compcams.com/lsr-cathedral-port-223-231-hydraulic-roller-cam-for-gm-ls-gen-iii-iv.html ). Assuming (?) that to be the case, this is a 3 bolt CAM. The Stock CAM can be either a one bolt or 3 bolt.
So my questions are:
1) What CAM should I use to bring the power down to 300 Hp @ 4500 RPM?.
2) Do I need to swap out the valve springs. I have received both yes and no answers to this question from parts shops. There are some Youtube video's by Richard Holdener that suggest bigger springs does not impact power output.
3) If it is a 3 bolt CompCam and the replacement CAM is a 1 bolt, is it as simple as replacing the CAM timing sprocket I think????
Input appreciated!
Rick
I am thinking of something like 190/191 at .050 in, .457/.466 and 115.5 LSA (Similar to a stock LM7). I'm very open to what CAM, but will be mindful of cost. The current CAM is too much power for my application, an airplane. I need ~300 hp @ 4500 RPM and I won't run the RPM any higher than 4500. I don't know, but googling the CAM specs leads me to CompCams ( https://www.compcams.com/lsr-cathedral-port-223-231-hydraulic-roller-cam-for-gm-ls-gen-iii-iv.html ). Assuming (?) that to be the case, this is a 3 bolt CAM. The Stock CAM can be either a one bolt or 3 bolt.
So my questions are:
1) What CAM should I use to bring the power down to 300 Hp @ 4500 RPM?.
2) Do I need to swap out the valve springs. I have received both yes and no answers to this question from parts shops. There are some Youtube video's by Richard Holdener that suggest bigger springs does not impact power output.
3) If it is a 3 bolt CompCam and the replacement CAM is a 1 bolt, is it as simple as replacing the CAM timing sprocket I think????
Input appreciated!
Rick
TECH Resident
Joined: Mar 2012
Posts: 860
Likes: 404
From: Texas
Just stick the factory cam in in and re-tune for the changes in volumetric efficiency.
Your existing valve springs should be fine, assuming that they don't have really high hours on them.
Since you don't know what cam bolt pattern you have, just replace the chain/ sprocket with what you already have once you take the cover off. Or reuse it. It may still be good.
This has got to be one of the first ever "I need LESS power!" posts on this board...
Why do you want less power, anyway?
Your existing valve springs should be fine, assuming that they don't have really high hours on them.
Since you don't know what cam bolt pattern you have, just replace the chain/ sprocket with what you already have once you take the cover off. Or reuse it. It may still be good.
This has got to be one of the first ever "I need LESS power!" posts on this board...
Why do you want less power, anyway?
TECH Senior Member
Joined: Jun 2016
Posts: 22,298
Likes: 3,619
From: Central Cal.
If you still have the original LH6 cam, put it back in.
The earlier ones (05-06) came with the L33 cam (193/193, .482/.482, 116 LSA)
After that they were- 196/201, .481/.481, 116+2 LSA
The earlier ones (05-06) came with the L33 cam (193/193, .482/.482, 116 LSA)
After that they were- 196/201, .481/.481, 116+2 LSA
Trending Topics
Thread Starter
Teching In
Joined: Nov 2011
Posts: 26
Likes: 5
From: Denver, CO
The Gearbox can handle up to 700 HP, but the Prop has a 300 HP limit. With a 300 HP engine and prop my airspeed is a max of 163 mph. But I won't know what power setting for that until I get in the air.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Thread Starter
Teching In
Joined: Nov 2011
Posts: 26
Likes: 5
From: Denver, CO
Now that I review feedback some thoughts. I don't have the old CAM's. But looking for a replacement I need to be mindful that the original CAM's were for DOD engines. Not something I want. I need to find a CAM similar to what G Atsma has suggested that is a non-DOD CAM. Something like the L33 or LH8 CAM. From the feedback I sense that others don't have an issue with the bigger valve springs. The people at ComCams indicated that their bigger CAM would use springs with a close pressure of 125 lbs (at 1.8") and an open pressure of 367 lbs (at 1.15"), and a rate of 372 lbs/inch. I won't be opening as far (.485" vs .610") far so less pressure, perhaps 280-300 lbs. I don't know what stock LH6 spring pressures are, but other reading suggests that these numbers are ok. THoughts?
Rick
Rick
I am looking to lower the power (yes not typical) in a LH6. The CAM spec's are 223/231 at .050 in .610/.617 lift with 112 LSA.The current CAM has output of 475HP/435TQ. (https://www.speedwaymotors.com/LS-Cr...TQ,497805.html ). This engine has upgraded valve springs as well.
I am thinking of something like 190/191 at .050 in, .457/.466 and 115.5 LSA (Similar to a stock LM7). I'm very open to what CAM, but will be mindful of cost. The current CAM is too much power for my application, an airplane. I need ~300 hp @ 4500 RPM and I won't run the RPM any higher than 4500. I don't know, but googling the CAM specs leads me to CompCams ( https://www.compcams.com/lsr-cathedr...en-iii-iv.html ). Assuming (?) that to be the case, this is a 3 bolt CAM. The Stock CAM can be either a one bolt or 3 bolt.
So my questions are:
1) What CAM should I use to bring the power down to 300 Hp @ 4500 RPM?.
2) Do I need to swap out the valve springs. I have received both yes and no answers to this question from parts shops. There are some Youtube video's by Richard Holdener that suggest bigger springs does not impact power output.
3) If it is a 3 bolt CompCam and the replacement CAM is a 1 bolt, is it as simple as replacing the CAM timing sprocket I think????
Input appreciated!
Rick
I am thinking of something like 190/191 at .050 in, .457/.466 and 115.5 LSA (Similar to a stock LM7). I'm very open to what CAM, but will be mindful of cost. The current CAM is too much power for my application, an airplane. I need ~300 hp @ 4500 RPM and I won't run the RPM any higher than 4500. I don't know, but googling the CAM specs leads me to CompCams ( https://www.compcams.com/lsr-cathedr...en-iii-iv.html ). Assuming (?) that to be the case, this is a 3 bolt CAM. The Stock CAM can be either a one bolt or 3 bolt.
So my questions are:
1) What CAM should I use to bring the power down to 300 Hp @ 4500 RPM?.
2) Do I need to swap out the valve springs. I have received both yes and no answers to this question from parts shops. There are some Youtube video's by Richard Holdener that suggest bigger springs does not impact power output.
3) If it is a 3 bolt CompCam and the replacement CAM is a 1 bolt, is it as simple as replacing the CAM timing sprocket I think????
Input appreciated!
Rick
Also, valvesprings should be matched to the cam specs. Sure, the stiffer springs you likely have to support the more aggressive cam will work. But that doesn't mean they're an ideal match. Reliability wise, I'm sure at a 4,500 rpm ceiling just about any spring will live. But you'll lose efficiency due to more friction than you'd have with matching springs. Curious about the 4,500 rpm ceiling. How is that governed, by you and the tach, or a governor?
Thread Starter
Teching In
Joined: Nov 2011
Posts: 26
Likes: 5
From: Denver, CO
Grinder11,
I understand the root of your concern and appreciate it. However, consider that this is not something new. Below are a few links to LS based planes as an FYI. The last link is for AutoPSRU that is a group that makes gear-boxes for BMW and LS engines. The link is a map of where they have product placed. I am not using their gear box, but an gearbox made by Stinger that is designed for aircraft. Stinger also makes airboat gearboxes.
http://www.moosemods.com/
http://www.sdsefi.com/gm.htm
https://www.v8seabee.com/
https://www.google.com/maps/d/viewer...6dDTRtfAC0ISF4
To your question regarding prop. Yes it is a 5.3L engine. The gear box and the prop are actually rated at 700 HP. But if I put a 700 HP engine/prop on the plane it will rip the wings off! To simplify dialog here I have stated 300 HP as the max for the prop and engine, but the facts are it is really the airframe. So YES, I am taking a conservative approach. But thank you for your comment and concern.
I understand the root of your concern and appreciate it. However, consider that this is not something new. Below are a few links to LS based planes as an FYI. The last link is for AutoPSRU that is a group that makes gear-boxes for BMW and LS engines. The link is a map of where they have product placed. I am not using their gear box, but an gearbox made by Stinger that is designed for aircraft. Stinger also makes airboat gearboxes.
http://www.sdsefi.com/gm.htm
https://www.v8seabee.com/
https://www.google.com/maps/d/viewer...6dDTRtfAC0ISF4
To your question regarding prop. Yes it is a 5.3L engine. The gear box and the prop are actually rated at 700 HP. But if I put a 700 HP engine/prop on the plane it will rip the wings off! To simplify dialog here I have stated 300 HP as the max for the prop and engine, but the facts are it is really the airframe. So YES, I am taking a conservative approach. But thank you for your comment and concern.
Thread Starter
Teching In
Joined: Nov 2011
Posts: 26
Likes: 5
From: Denver, CO
Grinder11,
To your question regarding governing the 4500 RPM. That is something that I will be able to program into the ECU. (http://www.sdsefi.com/index.html )
Rick
To your question regarding governing the 4500 RPM. That is something that I will be able to program into the ECU. (http://www.sdsefi.com/index.html )
Rick
As Grinder mentioned, you want to run only as much spring as necessary here, from a reliability standpoint, as well as a friction standpoint also. Friction adds heat. More spring rate adds heat to the oil. A set of Oem valvesprings can easily go 750k miles on the street, and are extremely reliable.
I feel that Spiders comments above about simply de-tuning this thing down should be considered also, as it adds economy and reliability to any engine to use less fuel and spark timing advance to make power. Just something to consider I suppose. Either way, we’ve had a few of these aviation builds here on Tech, and I always enjoy them a lot.
I feel that Spiders comments above about simply de-tuning this thing down should be considered also, as it adds economy and reliability to any engine to use less fuel and spark timing advance to make power. Just something to consider I suppose. Either way, we’ve had a few of these aviation builds here on Tech, and I always enjoy them a lot.
Thread Starter
Teching In
Joined: Nov 2011
Posts: 26
Likes: 5
From: Denver, CO
Scott (and others Grinder, Atsma, Snipper), thank you for your comments. I have had similar advice from another source that has done LS conversions for airplanes. They also mentioned that a stock LS CAM is not as tough (hard steel) as a performance CAM. As a result running a stock CAM with larger springs might cause premature wear of the CAM surfaces, more heat, etc. They also suggested when swapping the CAM to revert to lower pressure (stock) springs I will also look into the de-tuning. I am considering either the FiTech or the Simple Digital Systems ECU. Both are used in airplanes today.
TECH Resident
Joined: Jun 2011
Posts: 936
Likes: 472
If you're worried about cam wear and looking for peak torque, I'd custom order a Cam Motion with 198/206 113+4 .527/.527 specs on an 8620 core.
I haven't heard of SDS system, but FITech doesn't seem as reliable as the Holley Sniper. But as for reliability, I don't think you can beat the factory ECU.
I haven't heard of SDS system, but FITech doesn't seem as reliable as the Holley Sniper. But as for reliability, I don't think you can beat the factory ECU.
TECH Senior Member
Joined: Jun 2016
Posts: 22,298
Likes: 3,619
From: Central Cal.
lSA I like your cam suggestion! Duration and lift numbers that are close to the LQ9/late LQ4/LS1, BUT with a narrower LSA (3 degrees less). That should boost low RPM torque nicely; perfect for lower RPM aircraft duties.
If you're worried about cam wear and looking for peak torque, I'd custom order a Cam Motion with 198/206 113+4 .527/.527 specs on an 8620 core.
I haven't heard of SDS system, but FITech doesn't seem as reliable as the Holley Sniper. But as for reliability, I don't think you can beat the factory ECU.
I haven't heard of SDS system, but FITech doesn't seem as reliable as the Holley Sniper. But as for reliability, I don't think you can beat the factory ECU.