I've been prepping my motor for removal over the past few nights and have it almost ready to come out. The plan is a complete rebuild, and while I'm deciding on some bottom end stuff I need to get started on some cam research.

Here's the deal, while this will be my weekend fun car it still needs to pass emmissions. I had absolutely no problem passing emmissions with the HOTcam/ported heads on there through a 3" Random Technologies high flow catalytic converter. The car put out just a little over half of the allowable hydrocarbons and CO. This tells me that I have some room to step up to a bigger cam

I really do want some big numbers out of this car, however if it won't pass emmissions that really won't matter because I want to drive this thing on the street, take it to the car show, etc. I'm in search of the biggest cam I can put in there and still stay legal. I know this won't be easy to get a definite answer and most of the info will be subjective which is why I'm going to look at this stuff case by case.

So for you guys with bigger cams, I would like to know what kind of cam, if you've had it emmissions tested and if it passed or not, and what kind of power level/track times you have. Also a little commentary on what LSA and other cam characteristics have to do with emmissions would be great. I know that people have custom cams ground for maximum power, but what about custom cams ground for a compromise between maximum power and emmissions?

 

233/239 112ls, no emissions.

We ran it just for kicks on the emission dyno at work. CO was roughly 5 times the limit, NOX was a little above, and HC was WAY (10x+) above the limit.

Most of the small plants in the shop grass seemed to wither and die while it was on the dyno, so I guess it didnt pass.

 

Hahahaha, ok then. Thanks for the information!

 

Mine just failed with the GM846. (222/230, .543/.563). Hydrocarbons were 4 times the limit.

 

custom grind 228/238 .510/.510 (1.5 ratio rockers) on 112 lsa. I have never been able to dyno tune my car, my tune is originally fomr PCM forless. I passed easily on the 35mph cruising test. The idle test i failed Hydrocarbons miserably...more than twice allowed limit. I figure it's just becuase of the rich idle condition due to cam overlap. I ran the car in open loop and set the target AFR to 15.2:1 for my next test and passed. I didn't drivre it like that since i don't know how lean it's REALLY running, i passed barely that time. I promptly pulled into the emissions center parking lot though and reverted the tune with my laptop before driving it around. Oh, and i set the new tune up in the parking lot after driving to the test center, so the car was never driven on that tune. One day i'll make it to a dyno and really tune it.

 

LPE 383 package. 211/219 .533"/.560". LPE 1 3/4" shorties. Random Y pipe and converter, all AIR fittings, etc. Passed MD emissions test with cleaner air than anything I've ever owned. Emissions guy laughed. Now in PA with only visual inspection, so it passes here, too...

Stepping up to a 219/219 .560"/.560" and matching Super Ram intake..I'm told that this will also pass easily....

ET and trap speed in my sig....
--Alan

 

No way my car would pass. I have the 306 and if I stand behind it my head aches and my eyes water. But I love it, this thing sucks in small children and parts grass fields when I drive by.

 

That setup would be almost exactly what I want! Maybe the extra cubic inches help some? I don't know how this works......If I could trap around 118-120 NA like you I'd be very happy. I don't know how difficult it is to get LPE specs, but do you know what compression ratio you have?

 

I'll find out soon enough with mine. I'm planning on having my emissions tested soon after I get it dyno-tuned.

When I was looking to get a custom grind cam, I talked to the guys at Speed, Inc. in Schaumburg, Illinois (ls1speed.com), and their LT1 guru, Jim (INTMD8) said that pretty much anything past mid-.220's duration would probably not pass. I ended up going with a .223/.223 @.050 with .565/.565 lift.

Hopefully with a good tune I'll pass, and I won't have my license suspended.

So, take that for what it's worth.

 

We got my buddies 383 to pass with 847 cam, ported lt4, longtubes etc. Street tune, nothing changed in it. Car is Imp SS running high 12s at 110 on street tires. Gotta remember thats 700 more lbs than us though.

First time without cats...
288.8 HC, limit 99........fail
1.47% CO, limit .55%...fail
co2 12.87, limit na

He has the FLP setup, went back with the cats on it.
HC 23.2, limit 99.......pass
0% CO....limit .55%....pass

Visual here in ohio is pretty much nothing though. Just half assed put a mirror under the car to see if it has something that looks like a cat.

 

Something interesting- two 383's in this thread have passed with a moderate sized cam, while all the stock bottom end guys seem to be failing the emmissions test. How much does displacement actually have to do with emmissions? I was planning on buying a new rotating assembly for my car anyway, if a stroker will let me get away with a bigger cam I'll spend the extra money and do that.

 

FastZ...I'm running 11:1 comp ratio on 92 pump gas. The LPE specs are fairly simple...John just paid huge attention to detail and air velocity within the motor at somewhat low rpms (6000), and designed his stuff to pass emissions.

My set up is 4 bolt Corvette block, Callies 5140 crank, Oliver billet 5.85" rods, JE forged pistons, LT1 heads CNC ported and hand blended with 2.00"int 1.56"exh valves (lightweight manley stainless valves with titatanium retainers), 1.6 pro mag roller rockers, you already know the cam specs and its on their website, stock intake hand ported to match heads and the 58 mm TB, LPE CAI, Granatelli mass air, 1 3/4 shorties, stock fuel pump adj regulator, stock 1995 injectors...and tuned by John himself in 1995. There is nothing custom here it was just their 383 package in 1995. Call Ed at LPE 260-724-2552 for more info, but Ed recently told me that they have a "bullseye" on their backs now to make sure that everything that is put into a street car passes emissions before it leaves the shop.

If you read Car and Driver you'll note that they made over 800hp on pump gas with their twin turbo 427 Vette with all emissions stuff intact..That's rediculous.....

 

Thanks for the information. I'm really impressed with your times, I may try and put together a similar setup. I already have some ported LT1 castings with Manley RaceFlo 2.00x1.55 (or 1.56, can't remember) valves. The port job was my first attempt at a homeported set, and I'm happy with them but feel like I've learned some new tips since then. Before those heads go on I'll have them flowed to see how they are and if I can improve some.

Once again, thanks for the info.

 

You're welcome. There's plenty more hp to be had, but it's kinda cool to pass emissions and have a 10 year old motor that has never been apart since it was built. I'm also a big fan of bigger cubes, especially for a street engine. Build big torque and the hp will follow. It makes for fun stop light to stop light action. I think LPE focuses on relatively low engine speed (street engines)with a high lift, lower duration cam, and light weight smallish valves and fantastic port work and blending to keep air speed up, making good torque and hp at lower rpms...
--Alan

 

Mine is 242/252 on a 108 LSA. Don't even think about an emissions test with it. Birds fall out the sky dead when I drive by. Sounds bad a$$ though, LOL.
Steve...