Matt-B

Last year, I put a 416" L92 with ported L92 heads and L76 intake / injectors in a 2001 Camaro. 11:1 CR w/hollow LS3 intake valves. Car is an M6. Basically, I wanted a motor with more power and a little better low RPM manners than the LS1 with 224 cam / LS6 heads / LT headers.

I read enough to know that cam selection for L92 heads is different than cathedral port heads. The problem is that nobody is posting cam specs, and there continues to be much secrecy about the cams for these heads. So I wanted to relate my cam experience for those who are still searching.

After literally months of searching and speaking with several "pros", I was finally convinced that a 228/232 114+4 Comp XER would fit the bill. Everyone told me that even this was a tiny cam for a 416, and it would be tamer than the 224 cam / LS1 setup I had before.

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 found that I could improve the low RPM behavior by making the injectors fire later than stock (end of injection target table). Apparently, the reversion pulse of the 228/232 cam was pushing the fuel back out the big and lazy L92 intake ports at low RPM's. Even with the injection timing adjustment, it still wasn't perfect even in OLSD, and it really annoyed me that it behaved worse in OLSD at low RPM than my LS1 w/224 cam in CLMAF!!!

I finally got pissed and speced out a cam most would think is ridiculous. 216/224 116+2. Now here is the crazy thing: this tiny cam pulls harder than the 228/232 all the way up to 6000 RPM. Above this the 228/232 had an advantage, but not much (probably because of the 1.75" headers and L76 intake acting as a restrictions).

I don't have dyno numbers, but it pulls way harder than the cammed LS1, which I did get dynoed at 425 RWHP. I can't get traction in 2nd gear even when I roll into the throttle on good pavement. Even in 3rd gear, traction is iffy if there are any bumps at all, and I am running stock 3.42's. Shift point for best time is right around 6100 RPM, and the thing can lug to 1200 RPM in 6th gear no problem without setting O2 sensor insufficient switching codes.

So, what I gather from this is that even with 400+ cubes, when you are running L92 / LS3 heads, cam it the same as you would a LS1, and you can expect about the same results as far as how 'cammed' it is. I think with cathedral ports on a 416", the 228/232 cam would have been better, but with ported L92 heads, it was enough of a hog that it simply could not be ran in CL without surging below ~2200 RPM's.

jay_lt4

iTrader: (4)

Comp Cams XR281HR, intake 228@.050", 0.571, exhaust 230@.050" 0.573,, 112

this cam ran great in my s-10 6.0 L92 engine and im going to use it im my 2010 camaro 415ci LS3, in the 6.0 L92 it idled smoother than the gm hot cam and had way more power and rpm

mike c.

iTrader: (1)

I have a 402ci and my first cam was a custom spec 248/256 615/605 112. and it ran great. I then tried the LG Motorsports G6X3 cam for the l92's a smaller cam (dont know exact size 232/240 I think) but the smaller cam out pulls the bigger cam big time. As in your case,the smaller cam worked better for me too. The tq is much better down low and it drives better on the streets. It has a choppy muscle car sound but street drives real clean. Good luck to you. Thanks for the info too. And your right hiding cam specs on a info board sucks. I know why they do it,just wish they didn't.

ChucksZ06

iTrader: (9)

If you want it to idle and get away from the surge you have to lean it out. You cannot trust the wideband readings at low rpm/low load situations. I also thought most of the l92 cams had a larger split toward the exhaust.

1cdub

iTrader: (5)

agreed on the wide split...

last L92 cam was a 248/262

new L92 cam is a 255/271

firefighting1101

iTrader: (48)

im running a 238/250 in my 408 w/ l92's

Richard@WCCH

iTrader: (3)

I sound like a broken record on the phone telling guys to shrink down the valve timing events when using the L92/LS3 heads. These heads provide plenty of airflow at the faster cycling speeds and the shorter seat timing makes the low speed manners very tame. The result is a very wide powerband with lots of pedal responsive torque. IMO this is the real virtue of these heads.
Of course in the end it's really about what the guy driving the car feels he wants.

Thanks for posting this.

Richard

94 guy

iTrader: (125)

are these stock exhaust ports yall are speaking of?

NemeSS

iTrader: (127)

it seems like a moderate duration cam that favors exhaust duration is a good suit for l92's
i think a LPE GT11 would perform very well in a 10.75:1scr 375ci 6.0 engine
with l92 heads and vic. jr.

Matt-B

Intake and exhaust ports ported and hand sanded by Total Engine Airflow.

Another thing I like about the l92 heads / small cam combo is that it reminds me of my 1996 LT1 but with an extra 1000 RPM and a couple hundred more ft-lbs torque and horsepower.

I agre with WCCH. Low end manners are almost stock yet the cam acts way bigger than 216/224 at higher RPM's.

ShoddyHog

iTrader: (1)

My 228/232 on a stock LS2 bottom end drives damn near like stock, yet pulls like a beast.

Gerry

hymey

That's a great post. What pcm you using? LS1-B. Do you have a COS like efilives COS-3? That can be useful.

When tuning cammed L92 headed engines with an e38pcm, I find airflow adjustment is the only thing that dials out surging that occurs normally between 1200~1600rpm. It has an electronic TB(90mm). The e38 has a setting called max idle area. It shows up at 1.82 stock. This equates to 18.8% throttle opening. So if you are idling over the airflow correction may pull it back to 14% to obtain correct idle but as soon as you apply throttle to drive it-18.8% is the minimum throttle opening and hence minimum amount of airflow. So if we are applying 3% Pedal at cruise our total TP% is 18.8%+Pedal Percentage(3%) So that is 21.8% Total throttle.

If we reduce max idle area gradually until it drops to around 17%, You will notice at the same speeds with the same 3% pedal added(Total of 20%) The surging will be completely gone.

So in this case if there is to much airflow passing at low rpm surging will occur and reducing max idle area will fix the problem.

Having said that, Auto cars have Max Idle area 1 and Max idle area 2. Once Drive is selected it defaults to Max idle area 2, which has a crazy high figure of 3.0. This means when driving with only 3% pedal applied there may be a total percentage of over 25%! Surge city! The factory settings may be fine for a stock like camshaft with little reversion but with a camshaft starting to approach 0 degrees overlap @ 0.050" lift reversion starts to set in.

I have no dyno figures for you, but I have a 218/224/112+0 cam(.605",.601") xfi lobes in a L92 6.0L and it works awesome power hits hard, It is very aggressive when you want it to be and pulls from idle to 6600rpm and gets great economy. Sonny from Marranos spent $40000 dollars testing camshafts in aussie delivered L98s(6L with L92 heads and LS3 intake) and he told me he gets the best results with xfi lobes with L92 heads with small intake durations.

He told me the 218/224/112 cam is his favorite. I specced it up myself last year and I posted it on LS1.com.au in my sig and he asked me how it was going and that he had great real world results with this cam. Combined with SD tune and OTR intake and comp bump to 10.8:1 lets just say my brand new falken tyres are not looking good after only 3000kms, and I dont dump the clutch lol.

He also uses a 210 218 xfi cam and this cam is a stump puller.

He has been getting big power with the 224 230 112 and 114 cams on xfi lobes. I would like to try this too.

NemeSS

iTrader: (127)

is your ls2 equipped with l92 heads?

WKMCD

iTrader: (2)

Simply this...

ShoddyHog

iTrader: (1)

Yes. All mods are in my sig.

Gerry

See5

iTrader: (53)

I have noticed the low end surging with cammed C6 LS7s with E38s. It is tedious because it occurs in sixth gear cruising rpm range.

However- it is not at all apparent with numerous LS7> C5 retrofits using LS1 PCMs and ported LS3 heads. Agree on smaller cams.

Is this an E38 sensitivity as Hymey suggests?

69LT1Bird

iTrader: (1)

My cam is in my sig. I played around with Engine Analyzer Pro v3.3 for a while before choosing this and it seems to work. I had PatrickG spec me out a new one and it adds a little under the curve but not enough to justify the cost of a new cam.

I need some DR's to see how it really runs, the times and MPH in my sig is with me pedaling the crap out of it, I logged the run with HP Tuners and I didn't go WOT for 4 seconds. The car weighed about 3700 on that day.

Matt-B

Great to hear from you guys down under. The cam research you mention "Sonny from Marranos spent $40000 dollars testing camshafts in aussie delivered L98s(6L with L92 heads and LS3 intake)" is invaluable info.

Makes me want to go with the same 218/224/112 cam you are running and get midrange TQ through the roof

WizeAss

iTrader: (5)

Cam in my sig is the perfect cam in my opinion... much better than the other one I had in terms of power...

both the 244/248 (I put in originally) and the 236/236 (that Synergy Motorsports) spec'd up.


I also have a carb intake so I can get away with more reversion since it eats it up... in my opinion.

69LT1Bird

iTrader: (1)

I dumped that Aussie 218 224 112 +0 in Performance Trends to see what it looks like on my 6.0L L92 L76 setup, very nice. This is from the engine dyno mode

Engine_RPM 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500
Brk_Tq 323 363 359 406 459 494 514 499 476 451
Brake_HP 123 173 205 271 350 423 490 522 543 559


Chassis dyno 15% loss
Engine_RPM 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500
Road_Tq 274 308 305 346 390 420 437 424 404 384
Road_HP 104 147 174 230 297 360 416 444 462 475