Cam gurus: overlap question
Cam gurus: overlap question IVC 33 low duration low stall speed A4 Im specing a cam with the stock stall speed of 1300 for my truck. I like the idea of running alot of overlap with relatively smaller durations under 212 on the intake and IVC of 33, with a bigger exhaust lobe. The problem Im wondering about is having too much overlap and having to raise the idle too much and tweak the air tables. Im thinking I can have problem of it pulling too much at a stop light and being hard to stop, keep stationary or being very jerky.
Has anyone run into this problem with a very low stall speed and aggressive cam on an A4?
recommendations?
Has anyone run into this problem with a very low stall speed and aggressive cam on an A4?
recommendations?
Last edited by 02sierraz71_5.3; Feb 7, 2007 at 10:12 PM.
The challenge is that a stock stall limits your idle speed to about 700 rpm before you are fighting it at a stoplight. You can get a decent size cam to idle at that speed, but yes it will take some effort tuning. If you are unwilling to tune the cam, then stay small. Maybe something like a 206/218 114 111 would do the trick. With some basic tuning you could step up to 210/218 112 109.
I agree with Ragtop. You are really compromising your cam selection by staying with the stock stall. A better approach would be to get a Trailblazer L-6 torque converter installed. They're very cheap to buy and will still give you a high degree of towing, but they'll stall about 500 rpm more than stock. Just the ticket for running the beefier cam, but keeping stock driving manners.
If you stick with the stock stall, you'll most likely be fighting against the brake at idle unless you are a MASTER tuner.
If you stick with the stock stall, you'll most likely be fighting against the brake at idle unless you are a MASTER tuner.
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
Why does everybody forget all about the stall when doing a cam. How can you take full advantage of the cam without a stall. You can't...Atleast get like a 2500 stall or something along those lines and its not to much.
Originally Posted by 09CPTN
Will this be an issue for me as well in my 1998 T/A? I want to run my stock stall with my 230/232 .595.598 on a 114 lsa.
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
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From: arkansas
Originally Posted by bjamick
Why does everybody forget all about the stall when doing a cam. How can you take full advantage of the cam without a stall. You can't...Atleast get like a 2500 stall or something along those lines and its not to much.
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Originally Posted by Trail 70
We ran a 230-224 on a 114 lobe in a 2000 ss with stock converter. With a very good tuner we got it to idle a 650-700 in gear.
Originally Posted by 09CPTN
Will this be an issue for me as well in my 1998 T/A? I want to run my stock stall with my 230/232 .595.598 on a 114 lsa.
Originally Posted by 09CPTN
Will this be an issue for me as well in my 1998 T/A? I want to run my stock stall with my 230/232 .595.598 on a 114 lsa.
Ive currently got the stock stall in with an lpe gt2-5 222/222 112/112 it idles at 700 and has more overlap than the new cam Im specing. But I do notice some drivability issues at low speed when vacuum is pulled. Im not worried about the tuning just dont want a cam that is be impossible to stop. At 800 this one definately pulls on the brakes and tends to be jerky, I cant imagine with a cam that actually makes good tq down there how much of a pain it would be.
Does anyone have a rule of thumb they go by like dont go more than -5 @.05 overlap with a stock stall?
Does anyone have a rule of thumb they go by like dont go more than -5 @.05 overlap with a stock stall?
Originally Posted by Ragtop 99
The challenge is that a stock stall limits your idle speed to about 700 rpm before you are fighting it at a stoplight. You can get a decent size cam to idle at that speed, but yes it will take some effort tuning. If you are unwilling to tune the cam, then stay small. Maybe something like a 206/218 114 111 would do the trick. With some basic tuning you could step up to 210/218 112 109.
The advantage of 210* or 214* is you can use an XFI intake lobe and gain some real area under the curve compared with a 212 XE lobe. The XFI tend to run big so a 210 will be probably be a 212 when it is all said and done.
The 110 LSA will make great torque but I'd be concerned that those VEs will run out of breath a bit early on the top end.
With stock manifolds at -5 overlap, a 210/224 111 109 might be worth considering. However,given where you are coming from (IVC=43), doing a 210/224 112 111 is another choice. That's still a huge advance in IVC (IVC = 36), but it will still have some top end left in it and at -7 overlap your jerkiness should be easily tuned out.
The 110 LSA will make great torque but I'd be concerned that those VEs will run out of breath a bit early on the top end.
With stock manifolds at -5 overlap, a 210/224 111 109 might be worth considering. However,given where you are coming from (IVC=43), doing a 210/224 112 111 is another choice. That's still a huge advance in IVC (IVC = 36), but it will still have some top end left in it and at -7 overlap your jerkiness should be easily tuned out.
Originally Posted by Ragtop 99
The advantage of 210* or 214* is you can use an XFI intake lobe and gain some real area under the curve compared with a 212 XE lobe. The XFI tend to run big so a 210 will be probably be a 212 when it is all said and done.
The 110 LSA will make great torque but I'd be concerned that those VEs will run out of breath a bit early on the top end.
With stock manifolds at -5 overlap, a 210/224 111 109 might be worth considering. However,given where you are coming from (IVC=43), doing a 210/224 112 111 is another choice. That's still a huge advance in IVC (IVC = 36), but it will still have some top end left in it and at -7 overlap your jerkiness should be easily tuned out.
The 110 LSA will make great torque but I'd be concerned that those VEs will run out of breath a bit early on the top end.
With stock manifolds at -5 overlap, a 210/224 111 109 might be worth considering. However,given where you are coming from (IVC=43), doing a 210/224 112 111 is another choice. That's still a huge advance in IVC (IVC = 36), but it will still have some top end left in it and at -7 overlap your jerkiness should be easily tuned out.
I was thinking about a 210/220 but wondered about the big split.
Do you have a dyno of your cam?
My cam made 344 on a mustang dyno on the stock exhaust. very flat torque curve and go throttle response even at 2000 rpm.
I agree that with a good exhaust, you can run less exhaust duration. I didn't see it in your sig. Given what you just described, a 214/220 111 109 would be something to consider. I don't know how fast the LPE lobe ramps are, but they probably aren't as fast an the combo of an XFI/Xer, so that will help idle a bit too. Doing it on a 112 LSA would bring it down to -7 overlap and ensure a clean tune.
I agree that with a good exhaust, you can run less exhaust duration. I didn't see it in your sig. Given what you just described, a 214/220 111 109 would be something to consider. I don't know how fast the LPE lobe ramps are, but they probably aren't as fast an the combo of an XFI/Xer, so that will help idle a bit too. Doing it on a 112 LSA would bring it down to -7 overlap and ensure a clean tune.
Originally Posted by Ragtop 99
stock stall AND no headers (per your sig)?
I really dislike the idea of losing the MPG with a stall.
What about something milder, like a 2000-2500 stall, would that be acceptable?
Look in the Automatic Transmission forum. You'll see that a 2800 is pretty much the bottom.