LS2 guy looking for Spin's advice on a cam
03-12-2011, 02:54 AM
#21
Tech Contributor
Spin, you had me at hello...
In all seriousness, it seems you are recommending neither one of my original options. You got a bit too technical for me since I have very limited knowledge of cam design and engine response. I do trust your opinion though. Smaller intake is the way to go? Why shy away from the two recommendations I listed in my first post? Are they too choppy or provide too much surge at low end?
I don't want to go through all the work of a cam install (solo in my garage) just to want a bigger one later. Reading through many posts, many people who choose a slightly more mild cam want more in the long run. It sounds like the choppy idle can be tuned out as well as many of the drivability issues (with a good tuner of course).
With that said, do you still recommend the 224/230 114? If so, I will research that option.
Thank you for taking the time to help a stranger. Have a good weekend.
Sean
In all seriousness, it seems you are recommending neither one of my original options. You got a bit too technical for me since I have very limited knowledge of cam design and engine response. I do trust your opinion though. Smaller intake is the way to go? Why shy away from the two recommendations I listed in my first post? Are they too choppy or provide too much surge at low end?
I don't want to go through all the work of a cam install (solo in my garage) just to want a bigger one later. Reading through many posts, many people who choose a slightly more mild cam want more in the long run. It sounds like the choppy idle can be tuned out as well as many of the drivability issues (with a good tuner of course).
With that said, do you still recommend the 224/230 114? If so, I will research that option.
Thank you for taking the time to help a stranger. Have a good weekend.
Sean
The G1 is a 228/232 and I covered the power that size cam made in my car and in the video. Why do you say I dont recomend that one?
The 224/230 is a good cam but if you use a 228/232 or a 230/234 with optimum compression later, either of those two cams will beat the low end TQ of ANY small cam if you run them with optimum compression. When you see guys talking about great low end Tq advantages of smaller cams, those statements are only true if you are not increasing compression. If you run optimum compression, a 230/234 will beat any smaller cam from idle to redline. A 230/234 will be great with 11.7:1.
If you arent increasing compression, an earlier intake valve closing point is the only thing that affects TQ. Bigger intake durations close it later and wider LSAs close it later. When you arent changing heads or increasing compression, its a game of driveability vs low end TQ.
Summary:
224/230 114+2 great low end with stock compression
230/234 114+1 Better area under the curve and max power in the midband; good driveability with stock compression
228/232 114+2 Same as a 230/234 with 2% less peak power with stock compression.
If you increase compression to 11.7:1, a 230/234 will beat the low end of any of the above from idle to redline. With trick Flow 225's it hits 400rwtq at 3300-3400rpm.
Its .3-.4 secs faster in the 1/4 over a 224 cam or smaller.
03-12-2011, 10:07 AM
#22
Track Junky
Thread Starter
[QUOTE=SpinMonster;1577032917]Summary:
224/230 114+2 great low end with stock compression
230/234 114+1 Better area under the curve and max power in the midband; good driveability with stock compression
228/232 114+2 Same as a 230/234 with 2% less peak power with stock compression.
QUOTE]
Spin,
Thanks for clarifying, that's the info I (and I'm sure several others who are following this thread) have been waiting for.
I do plan on doing heads next year, so it looks like the G1 or 230/234 may still be the way to go. Once I pull the stock heads, I can bump the compression up a bit, through aftermarket head selection and/or gasket size, to optimize the cam as well.
In the arena of low end torque and max power, most of us (the LSx family) ultimatley care about area under the curve in the 3000-6000 rpm range, unless you are a hard core racer trying to squeak every last Hp out of the car. Once out of first gear, seeing <3000 rpm is unlikely when pushing the car.
I have debated FI in the future, but not sure if I need it. Even now I can't put the all Hp to the concrete until 3rd gear. I know the stock runflats aren't helping, so better tires are on the horizon once these are at the wear limiter. I think in a "weekend toy" or a "once every couple month" drag strip or road course car, 450 rwph is about all I need or can put to the ground reliably. Just knowing I have that kind of power under my foot is enough for me. Sometimes being in the garage under the hood can be more fun than the end result anyway...
Thank you for taking the time to help me understand.
Sean
224/230 114+2 great low end with stock compression
230/234 114+1 Better area under the curve and max power in the midband; good driveability with stock compression
228/232 114+2 Same as a 230/234 with 2% less peak power with stock compression.
QUOTE]
Spin,
Thanks for clarifying, that's the info I (and I'm sure several others who are following this thread) have been waiting for.
I do plan on doing heads next year, so it looks like the G1 or 230/234 may still be the way to go. Once I pull the stock heads, I can bump the compression up a bit, through aftermarket head selection and/or gasket size, to optimize the cam as well.
In the arena of low end torque and max power, most of us (the LSx family) ultimatley care about area under the curve in the 3000-6000 rpm range, unless you are a hard core racer trying to squeak every last Hp out of the car. Once out of first gear, seeing <3000 rpm is unlikely when pushing the car.
I have debated FI in the future, but not sure if I need it. Even now I can't put the all Hp to the concrete until 3rd gear. I know the stock runflats aren't helping, so better tires are on the horizon once these are at the wear limiter. I think in a "weekend toy" or a "once every couple month" drag strip or road course car, 450 rwph is about all I need or can put to the ground reliably. Just knowing I have that kind of power under my foot is enough for me. Sometimes being in the garage under the hood can be more fun than the end result anyway...
Thank you for taking the time to help me understand.
Sean
03-12-2011, 03:31 PM
#23
Tech Contributor
In the arena of low end torque and max power, most of us (the LSx family) ultimatley care about area under the curve in the 3000-6000 rpm range, unless you are a hard core racer trying to squeak every last Hp out of the car. Once out of first gear, seeing <3000 rpm is unlikely when pushing the car.
I have debated FI in the future, but not sure if I need it.
It also works great with FI but dont raise compression. If you want 650rwhp stay with stock compression (about 10psi). If you want more then lower compression to boost level.
03-12-2011, 08:46 PM
#26
Tech Contributor
If you run meth 650rwhp with stock compression is fine because you have 115 octane. If you're at my altitude, you can run far more compression than at sea level on the same octane.
My H/C car ran 704rwhp at 11psi and no issues with meth injection at 10.9 compression.
650rwhp w/meth doesnt need a compression drop. You can run 13:1 on a 1400hp FI car if you have the right fuel. The days of low compression and pump gas are over.
03-13-2011, 10:36 AM
#28
Go Canes!
03-13-2011, 01:15 PM
#29
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There is calculated (or static) and dynamic compression. A cam does not lower static compression because that number is strictly a mathematical calculation air volume when the piston is at bottom dead center vs. at top dead center.
Here is Wikipedia's definition of dynamic compression ratio:
Dynamic compression ratio
The calculated compression ratio, as given above, presumes that the cylinder is sealed at the bottom of the stroke, and that the volume compressed is the actual volume.
However: intake valve closure (sealing the cylinder) always takes place after BDC, which may cause some of the intake charge to be compressed backwards out of the cylinder by the rising piston at very low speeds; only the percentage of the stroke after intake valve closure is compressed. Intake port tuning and scavenging may allow a greater mass of charge (at a higher than atmospheric pressure) to be trapped in the cylinder than the static volume would suggest ( This "corrected" compression ratio is commonly called the "dynamic compression ratio".
This ratio is higher with more conservative (i.e., earlier, soon after BDC) intake cam timing, and lower with more radical (i.e., later, long after BDC) intake cam timing, but always lower than the static or "nominal" compression ratio.
The actual position of the piston can be determined by trigonometry, using the stroke length and the connecting rod length (measured between centers). The absolute cylinder pressure is the result of an exponent of the dynamic compression ratio. This exponent is a polytropic value for the ratio of variable heats for air and similar gases at the temperatures present. This compensates for the temperature rise caused by compression, as well as heat lost to the cylinder. Under ideal (adiabatic) conditions, the exponent would be 1.4, but a lower value, generally between 1.2 and 1.3 is used, since the amount of heat lost will vary among engines based on design, size and materials used, but provides useful results for purposes of comparison. For example, if the static compression ratio is 10:1, and the dynamic compression ratio is 7.5:1, a useful value for cylinder pressure would be (7.5)^1.3 × atmospheric pressure, or 13.7 bar. (× 14.7 psi at sea level = 201.8 psi. The pressure shown on a gauge would be the absolute pressure less atmospheric pressure, or 187.1 psi.)
The two corrections for dynamic compression ratio affect cylinder pressure in opposite directions, but not in equal strength. An engine with high static compression ratio and late intake valve closure will have a DCR similar to an engine with lower compression but earlier intake valve closure.
Additionally, the cylinder pressure developed when an engine is running will be higher than that shown in a compression test for several reasons.
* The much higher velocity of a piston when an engine is running versus cranking allows less time for pressure to bleed past the piston rings into the crankcase.
* a running engine is coating the cylinder walls with much more oil than an engine that is being cranked at low RPM, which helps the seal.
* the higher temperature of the cylinder will create higher pressures when running vs. a static test, even a test performed with the engine near operating temperature.
* A running engine does not stop taking air & fuel into the cylinder when the piston reaches BDC; The mixture that is rushing into the cylinder during the downstroke develops momentum and continues briefly after the vacuum ceases (in the same respect that rapidly opening a door will create a draft that continues after movement of the door ceases). This is called scavenging. Intake tuning, cylinder head design, valve timing and exhaust tuning determine how effectively an engine scavenges.
Here is Wikipedia's definition of dynamic compression ratio:
Dynamic compression ratio
The calculated compression ratio, as given above, presumes that the cylinder is sealed at the bottom of the stroke, and that the volume compressed is the actual volume.
However: intake valve closure (sealing the cylinder) always takes place after BDC, which may cause some of the intake charge to be compressed backwards out of the cylinder by the rising piston at very low speeds; only the percentage of the stroke after intake valve closure is compressed. Intake port tuning and scavenging may allow a greater mass of charge (at a higher than atmospheric pressure) to be trapped in the cylinder than the static volume would suggest ( This "corrected" compression ratio is commonly called the "dynamic compression ratio".
This ratio is higher with more conservative (i.e., earlier, soon after BDC) intake cam timing, and lower with more radical (i.e., later, long after BDC) intake cam timing, but always lower than the static or "nominal" compression ratio.
The actual position of the piston can be determined by trigonometry, using the stroke length and the connecting rod length (measured between centers). The absolute cylinder pressure is the result of an exponent of the dynamic compression ratio. This exponent is a polytropic value for the ratio of variable heats for air and similar gases at the temperatures present. This compensates for the temperature rise caused by compression, as well as heat lost to the cylinder. Under ideal (adiabatic) conditions, the exponent would be 1.4, but a lower value, generally between 1.2 and 1.3 is used, since the amount of heat lost will vary among engines based on design, size and materials used, but provides useful results for purposes of comparison. For example, if the static compression ratio is 10:1, and the dynamic compression ratio is 7.5:1, a useful value for cylinder pressure would be (7.5)^1.3 × atmospheric pressure, or 13.7 bar. (× 14.7 psi at sea level = 201.8 psi. The pressure shown on a gauge would be the absolute pressure less atmospheric pressure, or 187.1 psi.)
The two corrections for dynamic compression ratio affect cylinder pressure in opposite directions, but not in equal strength. An engine with high static compression ratio and late intake valve closure will have a DCR similar to an engine with lower compression but earlier intake valve closure.
Additionally, the cylinder pressure developed when an engine is running will be higher than that shown in a compression test for several reasons.
* The much higher velocity of a piston when an engine is running versus cranking allows less time for pressure to bleed past the piston rings into the crankcase.
* a running engine is coating the cylinder walls with much more oil than an engine that is being cranked at low RPM, which helps the seal.
* the higher temperature of the cylinder will create higher pressures when running vs. a static test, even a test performed with the engine near operating temperature.
* A running engine does not stop taking air & fuel into the cylinder when the piston reaches BDC; The mixture that is rushing into the cylinder during the downstroke develops momentum and continues briefly after the vacuum ceases (in the same respect that rapidly opening a door will create a draft that continues after movement of the door ceases). This is called scavenging. Intake tuning, cylinder head design, valve timing and exhaust tuning determine how effectively an engine scavenges.
03-13-2011, 01:39 PM
#30
Melting Slicks
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St. Jude Donor '08-'09-'10
There is calculated (or static) and dynamic compression. A cam does not lower static compression because that number is strictly a mathematical calculation air volume when the piston is at bottom dead center vs. at top dead center.
Here is Wikipedia's definition of dynamic compression ratio:
Dynamic compression ratio
The calculated compression ratio, as given above, presumes that the cylinder is sealed at the bottom of the stroke, and that the volume compressed is the actual volume.
However: intake valve closure (sealing the cylinder) always takes place after BDC, which may cause some of the intake charge to be compressed backwards out of the cylinder by the rising piston at very low speeds; only the percentage of the stroke after intake valve closure is compressed. Intake port tuning and scavenging may allow a greater mass of charge (at a higher than atmospheric pressure) to be trapped in the cylinder than the static volume would suggest ( This "corrected" compression ratio is commonly called the "dynamic compression ratio".
This ratio is higher with more conservative (i.e., earlier, soon after BDC) intake cam timing, and lower with more radical (i.e., later, long after BDC) intake cam timing, but always lower than the static or "nominal" compression ratio.
The actual position of the piston can be determined by trigonometry, using the stroke length and the connecting rod length (measured between centers). The absolute cylinder pressure is the result of an exponent of the dynamic compression ratio. This exponent is a polytropic value for the ratio of variable heats for air and similar gases at the temperatures present. This compensates for the temperature rise caused by compression, as well as heat lost to the cylinder. Under ideal (adiabatic) conditions, the exponent would be 1.4, but a lower value, generally between 1.2 and 1.3 is used, since the amount of heat lost will vary among engines based on design, size and materials used, but provides useful results for purposes of comparison. For example, if the static compression ratio is 10:1, and the dynamic compression ratio is 7.5:1, a useful value for cylinder pressure would be (7.5)^1.3 × atmospheric pressure, or 13.7 bar. (× 14.7 psi at sea level = 201.8 psi. The pressure shown on a gauge would be the absolute pressure less atmospheric pressure, or 187.1 psi.)
The two corrections for dynamic compression ratio affect cylinder pressure in opposite directions, but not in equal strength. An engine with high static compression ratio and late intake valve closure will have a DCR similar to an engine with lower compression but earlier intake valve closure.
Additionally, the cylinder pressure developed when an engine is running will be higher than that shown in a compression test for several reasons.
* The much higher velocity of a piston when an engine is running versus cranking allows less time for pressure to bleed past the piston rings into the crankcase.
* a running engine is coating the cylinder walls with much more oil than an engine that is being cranked at low RPM, which helps the seal.
* the higher temperature of the cylinder will create higher pressures when running vs. a static test, even a test performed with the engine near operating temperature.
* A running engine does not stop taking air & fuel into the cylinder when the piston reaches BDC; The mixture that is rushing into the cylinder during the downstroke develops momentum and continues briefly after the vacuum ceases (in the same respect that rapidly opening a door will create a draft that continues after movement of the door ceases). This is called scavenging. Intake tuning, cylinder head design, valve timing and exhaust tuning determine how effectively an engine scavenges.
Here is Wikipedia's definition of dynamic compression ratio:
Dynamic compression ratio
The calculated compression ratio, as given above, presumes that the cylinder is sealed at the bottom of the stroke, and that the volume compressed is the actual volume.
However: intake valve closure (sealing the cylinder) always takes place after BDC, which may cause some of the intake charge to be compressed backwards out of the cylinder by the rising piston at very low speeds; only the percentage of the stroke after intake valve closure is compressed. Intake port tuning and scavenging may allow a greater mass of charge (at a higher than atmospheric pressure) to be trapped in the cylinder than the static volume would suggest ( This "corrected" compression ratio is commonly called the "dynamic compression ratio".
This ratio is higher with more conservative (i.e., earlier, soon after BDC) intake cam timing, and lower with more radical (i.e., later, long after BDC) intake cam timing, but always lower than the static or "nominal" compression ratio.
The actual position of the piston can be determined by trigonometry, using the stroke length and the connecting rod length (measured between centers). The absolute cylinder pressure is the result of an exponent of the dynamic compression ratio. This exponent is a polytropic value for the ratio of variable heats for air and similar gases at the temperatures present. This compensates for the temperature rise caused by compression, as well as heat lost to the cylinder. Under ideal (adiabatic) conditions, the exponent would be 1.4, but a lower value, generally between 1.2 and 1.3 is used, since the amount of heat lost will vary among engines based on design, size and materials used, but provides useful results for purposes of comparison. For example, if the static compression ratio is 10:1, and the dynamic compression ratio is 7.5:1, a useful value for cylinder pressure would be (7.5)^1.3 × atmospheric pressure, or 13.7 bar. (× 14.7 psi at sea level = 201.8 psi. The pressure shown on a gauge would be the absolute pressure less atmospheric pressure, or 187.1 psi.)
The two corrections for dynamic compression ratio affect cylinder pressure in opposite directions, but not in equal strength. An engine with high static compression ratio and late intake valve closure will have a DCR similar to an engine with lower compression but earlier intake valve closure.
Additionally, the cylinder pressure developed when an engine is running will be higher than that shown in a compression test for several reasons.
* The much higher velocity of a piston when an engine is running versus cranking allows less time for pressure to bleed past the piston rings into the crankcase.
* a running engine is coating the cylinder walls with much more oil than an engine that is being cranked at low RPM, which helps the seal.
* the higher temperature of the cylinder will create higher pressures when running vs. a static test, even a test performed with the engine near operating temperature.
* A running engine does not stop taking air & fuel into the cylinder when the piston reaches BDC; The mixture that is rushing into the cylinder during the downstroke develops momentum and continues briefly after the vacuum ceases (in the same respect that rapidly opening a door will create a draft that continues after movement of the door ceases). This is called scavenging. Intake tuning, cylinder head design, valve timing and exhaust tuning determine how effectively an engine scavenges.
03-13-2011, 02:27 PM
#31
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Try it. If it blows up, you have the answer. Just kidding.
I don't know the right answer, but I'll throw this out anyway.........
Running Meth during times of light engine loads such as cruising on the street at low RPM seems unnecessary as the engine is not under high load where Meth has a real benefit of controlling knock.
At anything below a certain low MAP or grams/Cyl values, perhaps reduced ignition advance would be a better method to control KR since you are not trying to achieve max torque.
I don't know the right answer, but I'll throw this out anyway.........
Running Meth during times of light engine loads such as cruising on the street at low RPM seems unnecessary as the engine is not under high load where Meth has a real benefit of controlling knock.
At anything below a certain low MAP or grams/Cyl values, perhaps reduced ignition advance would be a better method to control KR since you are not trying to achieve max torque.
03-14-2011, 04:45 AM
#32
Track Junky
Thread Starter
I don't see any vendors selling Spin's 230/234 cam directly anymore.
Here's what I think I need to order, somebody please chime if I'm wrong:
230XFI / 234XER 114+2
intake .612 lift (as determined by lobe type)
exhaust .598 lift (as determined by lobe type)
Any specific vendors I should purchase through? Also, I need the three bolt cam, right? I have a 2005 LS2.
Here's what I think I need to order, somebody please chime if I'm wrong:
230XFI / 234XER 114+2
intake .612 lift (as determined by lobe type)
exhaust .598 lift (as determined by lobe type)
Any specific vendors I should purchase through? Also, I need the three bolt cam, right? I have a 2005 LS2.
03-14-2011, 09:19 AM
#33
Melting Slicks
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St. Jude Donor '08-'09-'10
I don't see any vendors selling Spin's 230/234 cam directly anymore.
Here's what I think I need to order, somebody please chime if I'm wrong:
230XFI / 234XER 114+2
intake .612 lift (as determined by lobe type)
exhaust .598 lift (as determined by lobe type)
Any specific vendors I should purchase through? Also, I need the three bolt cam, right? I have a 2005 LS2.
Here's what I think I need to order, somebody please chime if I'm wrong:
230XFI / 234XER 114+2
intake .612 lift (as determined by lobe type)
exhaust .598 lift (as determined by lobe type)
Any specific vendors I should purchase through? Also, I need the three bolt cam, right? I have a 2005 LS2.
"Ripper 3 " for example. They do get free research and I am certain they
copycat his proven results since he don't do copyright applications. They don't give Cam specs and keep it proprietary. Cartek has a Cam
follower which will read the geometrics of a Cam and see if it is off. There have been instances when the intake and exhaust lobes were
reversed. I dont know how a 234 XFI / 230 XER would work if at all but the point is sometimes these things can and do happen.
03-15-2011, 09:53 AM
#34
Instructor
I don't see any vendors selling Spin's 230/234 cam directly anymore.
Here's what I think I need to order, somebody please chime if I'm wrong:
230XFI / 234XER 114+2
intake .612 lift (as determined by lobe type)
exhaust .598 lift (as determined by lobe type)
Any specific vendors I should purchase through? Also, I need the three bolt cam, right? I have a 2005 LS2.
Here's what I think I need to order, somebody please chime if I'm wrong:
230XFI / 234XER 114+2
intake .612 lift (as determined by lobe type)
exhaust .598 lift (as determined by lobe type)
Any specific vendors I should purchase through? Also, I need the three bolt cam, right? I have a 2005 LS2.
03-15-2011, 01:14 PM
#35
Track Junky
Thread Starter
Thanks. Are you so doing pushrods, timing chain, high flow oil pump and UD pulley? What about heads? I'm entertaining the idea ofthe Patriot 243 heads, stage 2 they cost $1300 fully assembled and I could probably sell mine for $400 or so. No need to buy springs or the tool. That would leave you out of pocket about $550 more. I know patriot heads aren't the greatest, but you could verge 59cc heads which would bump your compression to what that cam really wants. I figure if I can pitch up another 30 Hp or so, might be worth it.
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03-15-2011, 01:27 PM
#36
Instructor
Thanks. Are you so doing pushrods, timing chain, high flow oil pump and UD pulley? What about heads? I'm entertaining the idea ofthe Patriot 243 heads, stage 2 they cost $1300 fully assembled and I could probably sell mine for $400 or so. No need to buy springs or the tool. That would leave you out of pocket about $550 more. I know patriot heads aren't the greatest, but you could verge 59cc heads which would bump your compression to what that cam really wants. I figure if I can pitch up another 30 Hp or so, might be worth it.
03-15-2011, 07:35 PM
#38
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The staggered pushrod length makes no sense to me. Should all be the same length.
The LS2 intake manifold is pretty poor especially after making mods. I picked up 31 rwhp with the FAST after doing heads, cam, and headers.
The LS2 intake manifold is pretty poor especially after making mods. I picked up 31 rwhp with the FAST after doing heads, cam, and headers.
03-16-2011, 09:31 AM
#39
Melting Slicks
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St. Jude Donor '08-'09-'10
is doing it on a budget. A Formatto stage 2 OEM can get you near 20 RWHP at a fraction of the cost of doing a PORTED FAST 102. You are correct the ported FAST will deliver well into 30+ RW and is my favorite mod. The cost was less than longtubes and gave me more RWHP & TQ.
of course these things are based on combos and when you put a mod on
what did you already have before butting it on.
03-16-2011, 10:28 AM
#40
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I wouldn't underestimate the performance of the LS2 Manifold if the Person is doing it on a budget. A Formatto stage 2 OEM can get you near 20 RWHP at a fraction of the cost of doing a PORTED FAST 102. You are correct the ported FAST will deliver well into 30+ RW and is my favorite mod. The cost was less than longtubes and gave me more RWHP & TQ. of course these things are based on combos and when you put a mod on what did you already have before putting it on.
Before I put on the FAST 92, I ported the stock LS2 intake and it made 427rwhp or a 15 rwhp gain.