Cam for L92 Heads: Lessons Learned
Real world testing is better, engine dynos are fine for some stuff.
The 222/238 114+4 XER lobe cam in my sig is a nice cam, real good torque, runs good but it also seems to run out of power up top. I run 97+ in the 1/8 and only 116 up top, you can see it in my logs that it flattens out around 5600 rpms and slowly rises.
If you put the cam in the Performane Trends software, you can see the same flat spot, 5500-5600 and the the rpms rise again. I don't see that as a coincidence. For cruising and overall driveablity it is ok, for getting down the track, not the best but good.
I am in the process of getting a new cam, if I get it done before it snow here I will try to get it back to the track. I am going to try a custom cam from Geoff at EPS.
I am running Patriot Gold springs and Trend pushrods so the valvetrain in stout, the tune is right on. Stock GM rocker arms. I shift at 6400 rpms.
The 222/238 114+4 XER lobe cam in my sig is a nice cam, real good torque, runs good but it also seems to run out of power up top. I run 97+ in the 1/8 and only 116 up top, you can see it in my logs that it flattens out around 5600 rpms and slowly rises.
If you put the cam in the Performane Trends software, you can see the same flat spot, 5500-5600 and the the rpms rise again. I don't see that as a coincidence. For cruising and overall driveablity it is ok, for getting down the track, not the best but good.
I am in the process of getting a new cam, if I get it done before it snow here I will try to get it back to the track. I am going to try a custom cam from Geoff at EPS.
I am running Patriot Gold springs and Trend pushrods so the valvetrain in stout, the tune is right on. Stock GM rocker arms. I shift at 6400 rpms.
Thread Starter
Teching In
Joined: Mar 2008
Posts: 20
Likes: 0
From: Pennsylvania
I read 69LT1's "222/238 114+4 XER lobe cam in my sig...flattens out around 5600 rpms and slowly rises". I thought maybe I had been deceiving myself thinking my 216/224 116 +2 cam in a 416 w/ported L92 heads wants to shift at about 6100 RPM. So last night, I took it out on a 2 mile rural straight stretch, turned around, and wound it out to 6300 in 2nd, 3rd and 4th to 130+ mph and felt zero dropoff before ~6000 RPM.
My intake and exhaust ports were aggressively ported, perhaps contributing to surprising power and TQ with such a small cam...?
If I had to do it over I would do a high lift 218/228 112 +0 for massive TQ up to 6000 RPM or a high lift 222/230 116 +2 for power up tp 6500 RPM...at the sacrifice of some midrange TQ. The latter cam has almost the same valve events as the General's LS7 cam, but with more overlap.
Tell you the truth, if I was to put my 346 back into my '01 Camaro, I would probably swap in a 228/232 114 +4 cam. I like bigger cams in small cube cathedral ports, but not L92's.
My intake and exhaust ports were aggressively ported, perhaps contributing to surprising power and TQ with such a small cam...?
If I had to do it over I would do a high lift 218/228 112 +0 for massive TQ up to 6000 RPM or a high lift 222/230 116 +2 for power up tp 6500 RPM...at the sacrifice of some midrange TQ. The latter cam has almost the same valve events as the General's LS7 cam, but with more overlap.
Tell you the truth, if I was to put my 346 back into my '01 Camaro, I would probably swap in a 228/232 114 +4 cam. I like bigger cams in small cube cathedral ports, but not L92's.
The small cams do make very good torque and horsepower on the big cube engines with dyno software. I tried the 219/235 mentioned in here and it performed worse in a 364 than a 418. I can see why you feel the power but the horsepower peaks pretty early (6000). I don't worry about the actual numbers in this software (Performance Trends 3.3) but the trends with changes are interesting to watch.
I would like to see dyno and track times to back this all up and not seat of the pants for the small cams.
I have seen my drop off on a dyno, track and logging data with HP Tuners. They all show the same thing. It could all come down to some valve event issues, reversion, I am not sure, I only know what my car is showing me.
I would like to see dyno and track times to back this all up and not seat of the pants for the small cams.
I have seen my drop off on a dyno, track and logging data with HP Tuners. They all show the same thing. It could all come down to some valve event issues, reversion, I am not sure, I only know what my car is showing me.
Last edited by 69LT1Bird; Oct 12, 2009 at 07:54 PM.
Teching In
Joined: Aug 2007
Posts: 5
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From: Tulsa, OK
After tuning for a couple months with a wideband, I had the VE and spark tables nearly perfect, yet in closed loop, it wouldn't stop surging until ~2200 RPM. (And yes, I scaled proportional fueling to the L92 injectors, had idle settings and IAC counts good, did CASE relearn, copied all injector values from L76, adjusted transient fuel, etc. )
I finally gave up on closed loop, and ran OLSD and OLMAF for a couple months. It ran much better at low RPM's in open loop, but despite numerous wideband sessions, the motor still didn't really stop running slightly uneven under light load until 2000 RPM and didn't truly start to purr until 2500 RPM. (Under higher load such as when going uphill, it ran great down to ~1200 RPM, in OL.) I probably did 50 flashes adjusting fuel and spark, and no combination fixed the low RPM / light load surging.
I finally gave up on closed loop, and ran OLSD and OLMAF for a couple months. It ran much better at low RPM's in open loop, but despite numerous wideband sessions, the motor still didn't really stop running slightly uneven under light load until 2000 RPM and didn't truly start to purr until 2500 RPM. (Under higher load such as when going uphill, it ran great down to ~1200 RPM, in OL.) I probably did 50 flashes adjusting fuel and spark, and no combination fixed the low RPM / light load surging.
If anyone else has any experience, I'd love to hear.
I have zero driveability issues today, it is just not getting it done up top.
None of the cam here, except a couple of very wild ones, should have any issues below 2000 rpms if tuned correctly. The guys with the 408's and 418's actually have pretty average cams for what they are. If you are having surging from a 236 236 cam its time to learn how to tune better or find a new tuner.
None of the cam here, except a couple of very wild ones, should have any issues below 2000 rpms if tuned correctly. The guys with the 408's and 418's actually have pretty average cams for what they are. If you are having surging from a 236 236 cam its time to learn how to tune better or find a new tuner.
Thread Starter
Teching In
Joined: Mar 2008
Posts: 20
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From: Pennsylvania
My goal for the 416 L92 was the same or slightly more peak HP than my TR224 LS6, but with perfect behavior during coast down at 1000 RPM or less in closed loop. I also wanted excellent gas mileage. The 228/232 114 +4 cam didn't do it. The 216/224 116 +2 does do it.
I was prepared for a large loss in migrange TQ and peak HP when downsizing the cam. I am still at a total loss as to how I lost hardly any power or RPM. I had many carburated engines and cams, and when I moved into EFI...a supercharged LT1, a built LS6, a built 6.0 LQ4, and now this 416 L92.
I was always very sensitive to power changes a cam swap or rejetting a carb had and would notice immediately. While all of the former motors were OK as far as power, this 416 simply blows them all away and does not react the same with such a small cam.
I have been trying to get dyno numbers, but with kids, full time job, and business on the side, it leaves little time.
I was prepared for a large loss in migrange TQ and peak HP when downsizing the cam. I am still at a total loss as to how I lost hardly any power or RPM. I had many carburated engines and cams, and when I moved into EFI...a supercharged LT1, a built LS6, a built 6.0 LQ4, and now this 416 L92.
I was always very sensitive to power changes a cam swap or rejetting a carb had and would notice immediately. While all of the former motors were OK as far as power, this 416 simply blows them all away and does not react the same with such a small cam.
I have been trying to get dyno numbers, but with kids, full time job, and business on the side, it leaves little time.
Choosing a cam for a 416 L92 is a daunting task. The opinions seems to be so varied.
The intake reversion on a L92 with certain cams (at least with the 230/242 114 cam I have) is very real. The engine I was using had an oil issue and you can actually see (spray patterns) how the intake reversion blew oil throughout the heads and intake.
Swapping from L92 heads (and ported intake) to stock heads and stock intake, resulted in a car that felt (SOTP) like it had more power, the low speed drivability improved, and the intake reversion was immediately gone.
The intake reversion on a L92 with certain cams (at least with the 230/242 114 cam I have) is very real. The engine I was using had an oil issue and you can actually see (spray patterns) how the intake reversion blew oil throughout the heads and intake.
Swapping from L92 heads (and ported intake) to stock heads and stock intake, resulted in a car that felt (SOTP) like it had more power, the low speed drivability improved, and the intake reversion was immediately gone.
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There is alot that goes into a Cam to get the power and drivability.Only a few people/shops have it nailed down.You can scratch your head and go by duration,lift,LSA and overlaps but that won't be accurate on what the result should be.
Since this thread was posted we've done a few more L92 and LS3 head Camshafts.I was even surprised to find a 108LSA Cam that made great midrange power and drivability was plainly awesome from 1100rpm 1st gear parking lot stuff to 6400rpm redline.
There is still alot more testing to go into these heads.The intake to exhaust airflow split is huge and to hit a Cam right is hard. I'm not a fan of the midrange dips most get with the big Cams so we tend to stay with the smaller Cams.As of now I still prefer a nice set of TFS's over L92's due to the average power.
Since this thread was posted we've done a few more L92 and LS3 head Camshafts.I was even surprised to find a 108LSA Cam that made great midrange power and drivability was plainly awesome from 1100rpm 1st gear parking lot stuff to 6400rpm redline.
There is still alot more testing to go into these heads.The intake to exhaust airflow split is huge and to hit a Cam right is hard. I'm not a fan of the midrange dips most get with the big Cams so we tend to stay with the smaller Cams.As of now I still prefer a nice set of TFS's over L92's due to the average power.
