115+3 versus 114+2 Cam LSA
06-24-2006, 10:38 AM
#41
Lots of stuff here.
Can I ask what lobe you are planning to use?
Now let me just say what I'm seeing here:
1. It seems nearly everyone is recommending a slight retard in IVC. This depends on what your idea of low speed torque is. In a stock geared truck, that may be 12-1500rpm.
2. GM sent it out the door with -24.5 deg oiverlap @.050. The range of recommendations seems to be -4 to -13. I believe no one has passed emissions below -4. Wouldn't this be the primary idle issue?
3. Everyone seems to whant to keep the EVO at around 43. Bret tightens it some, the CheatTR opens it some.
4. No one is mentioning the lobe or the seat duration. Isn't the stock lobe around .520 lift with a 60-65° major intensity?
5. You are worried about your wife noticing a lope at idle, and you are installing headers. Ummm...she is deaf and you are figuring she will feel the lope from vibraton? Or your adding 50# of sound deadening?
6. My truck spends its highway time struggling around 4500-5000rpm...although with 9000# hanging out the back. For street use I might have defined the problem as keep current torque curve from 1000-3000 and raise torque around 5000. Speeds determined by gearing; in my case a 2500 with 4.10 gears.
So, using Bret's IVC 40 and the consensus EVO of 43. Move the IVO to Patrick's most conservative of the suggestions -8. Keeping the overlap to halfway between the stock -24.5 andand the most conservative -13 at say -18 gives an EVC of -10.
The resulting cam is a 212/213 115 115+1. Using XFI lobes, that would be a 210/212 116+1 to 114.5/+1.5 or a 214/218 113.5/+.5 or 117/+2. The XFI lobes are a lot more aggressive than stock, with .580-.600 lift with 1.7 rockers and this duration.
Forgoing the headers, this maybe a 210/218 114/-1.
Can I ask what lobe you are planning to use?
Now let me just say what I'm seeing here:
1. It seems nearly everyone is recommending a slight retard in IVC. This depends on what your idea of low speed torque is. In a stock geared truck, that may be 12-1500rpm.
2. GM sent it out the door with -24.5 deg oiverlap @.050. The range of recommendations seems to be -4 to -13. I believe no one has passed emissions below -4. Wouldn't this be the primary idle issue?
3. Everyone seems to whant to keep the EVO at around 43. Bret tightens it some, the CheatTR opens it some.
4. No one is mentioning the lobe or the seat duration. Isn't the stock lobe around .520 lift with a 60-65° major intensity?
5. You are worried about your wife noticing a lope at idle, and you are installing headers. Ummm...she is deaf and you are figuring she will feel the lope from vibraton? Or your adding 50# of sound deadening?
6. My truck spends its highway time struggling around 4500-5000rpm...although with 9000# hanging out the back. For street use I might have defined the problem as keep current torque curve from 1000-3000 and raise torque around 5000. Speeds determined by gearing; in my case a 2500 with 4.10 gears.
So, using Bret's IVC 40 and the consensus EVO of 43. Move the IVO to Patrick's most conservative of the suggestions -8. Keeping the overlap to halfway between the stock -24.5 andand the most conservative -13 at say -18 gives an EVC of -10.
The resulting cam is a 212/213 115 115+1. Using XFI lobes, that would be a 210/212 116+1 to 114.5/+1.5 or a 214/218 113.5/+.5 or 117/+2. The XFI lobes are a lot more aggressive than stock, with .580-.600 lift with 1.7 rockers and this duration.
Forgoing the headers, this maybe a 210/218 114/-1.
06-24-2006, 11:57 AM
#42
David,
#2. You might want to look into that emissions -4 thing a little more.
My recomendation was to outperform over the entire curve, not make the most TQ down low. If you wanted to do that, or if that's what he wanted it would be another thing all together.... I don't think that was his goal though.
Bret
#2. You might want to look into that emissions -4 thing a little more.
My recomendation was to outperform over the entire curve, not make the most TQ down low. If you wanted to do that, or if that's what he wanted it would be another thing all together.... I don't think that was his goal though.
Bret
06-24-2006, 01:03 PM
#43
I think you where right on from a performance standpoint: it needed more overlap.
However, he also said "its a DD, and usually by my wife so I need to keep it smooooth" and its a "2006 Chevrolet Trailbazer SS-LT. Silverstone / Ebony, AWD. LS2" while his other car is a "2002 Pontiac T/A SLP Firehawk #729. 430rwhp/393rwtq". Unless he is looking for a divorce, I don't think is wife wants the Trailblazer to run like the Firebird.
Actually, this would be a great supercharger application with stock exhaust and stock or mild supercharger cam, which would have little overlap and a small intake relative to the exhaust...maybe a 204/214 118 or so.
However, he also said "its a DD, and usually by my wife so I need to keep it smooooth" and its a "2006 Chevrolet Trailbazer SS-LT. Silverstone / Ebony, AWD. LS2" while his other car is a "2002 Pontiac T/A SLP Firehawk #729. 430rwhp/393rwtq". Unless he is looking for a divorce, I don't think is wife wants the Trailblazer to run like the Firebird.
Actually, this would be a great supercharger application with stock exhaust and stock or mild supercharger cam, which would have little overlap and a small intake relative to the exhaust...maybe a 204/214 118 or so.
06-24-2006, 09:53 PM
#45
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Originally Posted by DavidNJ
Lots of stuff here.
Can I ask what lobe you are planning to use?
Can I ask what lobe you are planning to use?
2. GM sent it out the door with -24.5 deg oiverlap @.050. The range of recommendations seems to be -4 to -13. I believe no one has passed emissions below -4. Wouldn't this be the primary idle issue?
3. Everyone seems to whant to keep the EVO at around 43. Bret tightens it some, the CheatTR opens it some.
4. No one is mentioning the lobe or the seat duration. Isn't the stock lobe around .520 lift with a 60-65° major intensity?
5. You are worried about your wife noticing a lope at idle, and you are installing headers. Ummm...she is deaf and you are figuring she will feel the lope from vibraton? Or your adding 50# of sound deadening?
So, using Bret's IVC 40 and the consensus EVO of 43. Move the IVO to Patrick's most conservative of the suggestions -8. Keeping the overlap to halfway between the stock -24.5 andand the most conservative -13 at say -18 gives an EVC of -10.
The resulting cam is a 212/213 115 115+1. Using XFI lobes, that would be a 210/212 116+1 to 114.5/+1.5 or a 214/218 113.5/+.5 or 117/+2. The XFI lobes are a lot more aggressive than stock, with .580-.600 lift with 1.7 rockers and this duration.
Forgoing the headers, this maybe a 210/218 114/-1.
The resulting cam is a 212/213 115 115+1. Using XFI lobes, that would be a 210/212 116+1 to 114.5/+1.5 or a 214/218 113.5/+.5 or 117/+2. The XFI lobes are a lot more aggressive than stock, with .580-.600 lift with 1.7 rockers and this duration.
Forgoing the headers, this maybe a 210/218 114/-1.
06-24-2006, 10:02 PM
#46
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Originally Posted by DavidNJ
However, he also said "its a DD, and usually by my wife so I need to keep it smooooth" and its a "2006 Chevrolet Trailbazer SS-LT. Silverstone / Ebony, AWD. LS2" while his other car is a "2002 Pontiac T/A SLP Firehawk #729. 430rwhp/393rwtq". Unless he is looking for a divorce, I don't think is wife wants the Trailblazer to run like the Firebird.
Seriously, though, my goal for the SS is a solid 12.x *one* time at the track, complete with my two baby/child seats in the back... Coming from estimated ~14.0 stock, a mild cam w/ AFR's & LTs ought to get me into the 12s.
Actually, this would be a great supercharger application with stock exhaust and stock or mild supercharger cam, which would have little overlap and a small intake relative to the exhaust...maybe a 204/214 118 or so.
06-24-2006, 10:57 PM
#47
The XFIs will probably out last the much older design XEs with their .040 less lift.
The S/C would probably get you the performance with virtually no drop in street performance. It is what a manufacturer would do, and GM has done on other cars (Cadillac STS-V for instance). The H/C produces more tradeoffs in driveability, NVH, economy, emissions, etc.
The S/C would probably get you the performance with virtually no drop in street performance. It is what a manufacturer would do, and GM has done on other cars (Cadillac STS-V for instance). The H/C produces more tradeoffs in driveability, NVH, economy, emissions, etc.
06-25-2006, 10:17 AM
#48
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Originally Posted by DavidNJ
The XFIs will probably out last the much older design XEs with their .040 less lift.
The S/C would probably get you the performance with virtually no drop in street performance. It is what a manufacturer would do, and GM has done on other cars (Cadillac STS-V for instance). The H/C produces more tradeoffs in driveability, NVH, economy, emissions, etc.
06-25-2006, 10:37 AM
#49
You mean a Mercedes C230 doesn't count? A various VWs, Cobalts, etc?
The spring wear is a function of the speed of the movement as much as the lift. The XFI's have better profiles...because they are years newer with more development behind them. Note the XFIs have different exhaust profiles with a softer landing.
The spring wear is a function of the speed of the movement as much as the lift. The XFI's have better profiles...because they are years newer with more development behind them. Note the XFIs have different exhaust profiles with a softer landing.
06-25-2006, 11:41 AM
#50
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Originally Posted by DavidNJ
You mean a Mercedes C230 doesn't count? A various VWs, Cobalts, etc?
And that longevity applies to the engine as well as the aftermarket SC - Unless they're sourced with an OEM program, Paxton / ATI / etc. all don't have nearly the budget nor test-resources that OEMs have, thus I can't imagine they would last beyond the lifetime of the engine....
We're digressing a bit here, but that's cool. Its all good info.
Last edited by 02RedHawk; 06-25-2006 at 11:48 AM.
06-25-2006, 07:37 PM
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Originally Posted by Predator-Z
Red Hawk, after all this,I'm at a loss man. What exactly do you want?
This is the cam I put together for my vette, since I did't want to give up any street manners.
210/224, .555/.567 115+1 XE lobed
I gained 32 rwhp over stock (with tune), stock manifolds,cats and exhaust. It has a IVC of 39, peaks at 5900, shift by 6100. Only other mods are halltech, ported TB, and a wideband gage for the tune.
Idle is stock, no lope, basically acts like stock (stock verter too)
I ran out of $$ (had to build new motor for Z28) before I could put on a set of AFR 205's which with a Magnaflow X pipe should get me close to my 400 rwhp goal. Still I'm at 362 rwhp now.
This is the cam I put together for my vette, since I did't want to give up any street manners.
210/224, .555/.567 115+1 XE lobed
I gained 32 rwhp over stock (with tune), stock manifolds,cats and exhaust. It has a IVC of 39, peaks at 5900, shift by 6100. Only other mods are halltech, ported TB, and a wideband gage for the tune.
Idle is stock, no lope, basically acts like stock (stock verter too)
I ran out of $$ (had to build new motor for Z28) before I could put on a set of AFR 205's which with a Magnaflow X pipe should get me close to my 400 rwhp goal. Still I'm at 362 rwhp now.
I suppose I still had/have a twofold purpose -
1) Understand for myself how the valve-events affect cam power curves.
2) Decide upon an 'optimal' cam for my application....because I'm still getting a bit of conflicting info from various sources (although here is definitely the most consistent). Smooth idle, stock stall (2100rpm), and a good increase in power from 3k-5k, with the power hanging on until shiftpoints.
I hadn't even considered the XFI lobes till now; figuring that they were moreorless on-par with an XE-R type. Thus, I had been sticking to the XE-high lift variant as my preference.
TR says the 212/218 114 will easily run out of steam before a 6300 shift point. Trying to figure out why they're saying this.
Hearing VTodd's feedback after his install will be very beneficial, but I still want to do my homework regardless....
06-25-2006, 07:58 PM
#53
TR says the 212/218 114 will easily run out of steam before a 6300 shift point. Trying to figure out why they're saying this.
What you just seeing is different takes on the tradeoffs. And for any different engine they are dependent on different intake and exhaust tuning and combustion dynamics. The big ones you are seeing involve starting intake flow during the exhaust stroke vs. the reversion at low speeds/idle (the lopey idle), additional mixture flowing in during the compression stroke vs. less compression at low engine speeds, evacuating the exhaust gases at the tail end of the power stroke vs. lost parts of the power stroke at lower engine speeds, and component costs and maintenace vs. how quickly you are moving the components.
There is a reason you stock truck can out drag a stock 1969 Corvette while getting better mileage and meeting emissions regulations that weren't even thought of then.
06-25-2006, 08:41 PM
#54
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Originally Posted by DavidNJ
And a stock 204/211 116 won't?
According to TR, it doesn't because of the mildness of the lobes (ie, total duration) on the stock cam.
06-26-2006, 03:14 AM
#56
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See, Why do we do custom cam?
Some is to try and find the most power in a certain range, some like my Vette's cam was to fit specific criteria.
Different folks have different strokes, while all of us comprehending cam dynamics have common points, we all have different ideas about achieving that.
Thus the different approach from individual to individual.
Things to consider:
Not to fear lobe rates since spring tech is up to par and at proper height and pressure, the springs will last awhile. (still spring maintenance is necessary once a year)
Make a plan, then stick to it, While I agree that Supercharging is a nice option, it is also up to 4X more expensive than H/C. Keep in mind that Superchargers do wear out too, ask some of the poeple that have had them for awhile.
Some is to try and find the most power in a certain range, some like my Vette's cam was to fit specific criteria.
Different folks have different strokes, while all of us comprehending cam dynamics have common points, we all have different ideas about achieving that.
Thus the different approach from individual to individual.
Things to consider:
Not to fear lobe rates since spring tech is up to par and at proper height and pressure, the springs will last awhile. (still spring maintenance is necessary once a year)
Make a plan, then stick to it, While I agree that Supercharging is a nice option, it is also up to 4X more expensive than H/C. Keep in mind that Superchargers do wear out too, ask some of the poeple that have had them for awhile.
