As for as I know there's 3 sniffe tests to pass but no visual and no OBDII. If the car 'could' pass without CATS there's no legal reason to run them, of course it isn't going to happen though. But the Land Rover TD5 engine (diesel) passes without the need for CATS so it does happen.

The test are:
-start up
-idle for X number of seconds
-and holdind in the rpm range, I think it has to be something like 2500-4500 range fot X number of seconds

What I'm not certain is exaclty what gases they are checking for or in which quantities.

 

CO output

 

Right'o think I've found it. There's two main tests if it passes the first one then it's PASSED if it fails it goes onto the second one.

BET - Basic Emissions Test

This is just with a probe in the exhaust pipe.

The BET standards are:

Fast idle 2500-3000rpm

CO no more than 0.3%

HC no more than 200 parts per million

Lambda between 0.97 and 1.03

Normal idle 450-1500rpm

CO no more than 0.5%

If it fails it has to go thru the Advanced Emissions Test. I can't find out exactly what it envolves but I think it ensures the engine is a X temp and no electrical devices (air con, etc.) are being used. I assume it would still have the meet the same numbers as above.

Anyone know how this varies compared to US emissions testing. Would selective tuning of the a/f & timing combined with CATS be enough to pass do you think or is it still a no no with these cams?

 

TTT

Anyone got any info on what these sort of cams fail emissions for, as in specifically which gas?

 

In the US, cars are usually held to a standard for the model year of the vehicle. Not sure if the numbers you provided are flat standard or for your model year.

Increased overlap from a performance cam usually raises HC levels, which a catalyst can control, within reason. CO is usually the by-product of incomplete combustion. If compression is raised, combustion temps are higher, and NOx levels generally increase.

If you look at PREDATOR-Z's advice, a smaller cam will net you greater gains in the range you are looking for, keep operating rpm's under the threshold where trans modifications become necessary, and possibly pass emissions without two cam swaps for each test interval.

 

Been speaking with a few people here and they reckon as long as it's a good CAT in working order and a closed loop lambda it should be fine on the emissions front even with something as wild as the T-Rex.

Nox emissions aren't an issue as they don't test for them, it's just CO2 and HC.

Anyhow I haven't really decided what rpm range to use yet. There seem to be several people running big cams and not spinning them anymore than I itend so I'm a little perplexed as what would be a better alternative. I really can't beleive most cammed LS1's really run to 7000rpm and beyond and I'm looking at ~6600rpm +- and if the convertors not locked that would make more than enough rpm for me.

But I know these guys REALLY know their stuff too, so I'll listen, research and learn.

 

Biggest thing is that a cam is always a compromise. You trade power down low for power up high. If you run a cam like the T-Rex that spins to 7200, but you only rev it to 6200-6500, you are not only missing out on nearly 1000 rpm of the operating range it will give you, you are also trading away torque in the area you need it when you drive your car every day. Your converter will help, but that cam just doesn't seem right for a car that isn't being setup for the track.

 

That's fine but I'm not looking at the T-Rex and never was. Also my car isn't a daily driven car and probably never will be.

I also understand that a cam moves the powerband up the rpms, but PatrickG's Torque cam is still making 320rwtq at 2500rpm which I personally think is pretty good going considering a stock LT1 only makes a maximum of 325lb ft at the flywheel.

 

You need to look at the VEs, head flow, SCR, DCR to understand why it does that.
The same cam on stock heads will not put out nearly the same numbers.
This is why I repeat, quit looking at off the shelf cams and just get one designed wth your combo and power range in mind.

 

this is an excellent idea, but after contacting the sponsors...they've all mentioned off the shelf cams. it seems that unless i am building a stroker motor from the ground up, they won't go out of their way to spec a custom cam. alan futral so far is the only one to spec a custom cam. 1 out of 4 isn't very good. ..just something to consider in the good fight of choosing the right cam.

 

Geoff at thunder speced a cam out for me, though i came up with my own numbers, he was glad to look it over and make some suggestions.

 

I understand that my setup won't be anywhere near one with good heads and FAST 90/90, but there are some cam only guys that still make decent power.

As for designing my own cam - I'd love to but in all honesty I don't feel my expertise and first hand experience is sufficient to do so.

Also speaking with US suppliers such as Thunder Racing isn't easy when your on this side of the Atlantic. Not only are the time zone issues a bugger but also the shear cost of making international calls. Emailing is fine, but I've emailed several companies in the past on more than one occasion and have received nothing in the way of a response.

So unless someone is kindly offering to help design me a cam I'll just have to do the best I can

Here's where I'm at so far from reading all the info provided.

If these are the mods I go for:
-usual bolt on's (LT's, catted Y, catback, LS6 intake, ported TB, lid, etc.)
-3.42 rear gears
-3600rpm stall
-stock bottom end
-PRC CNC LS6 heads
-Thunder Racing Cam install kit (Comp 921 springs, push rods, etc.)
-Ported LS6 oil pump
-LS2 timing chain
-EFI Live tuning software
-Fuel injectors
-ARP studs/bolts (or what ever is needed to safely spin the motor higher)

Requirements:
-lopey idle
-big power
-savage power delivery would be acceptable as opposed to unwelcome
-street doable as opposed to DD, but must be possible to drive at lower speeds
-rev range, probably about as much as the stock short block can take within reason ([b]how much is this?[b]), as for the tranny well I'll just see how it holds up, if it doesn't then I'll cross that bridge when I get to it
-the aim I guess would be maximising potential, even if it means sacrificing some of the driveability
-noise and emissions will not be a concern at this point in time
-I don't want to go too middle of the road and then regret it later, so wild as opposed to mild is the order of the day

So based on the above what sort of custom grind would you recommend?

 

If you want lowend torque and topend power just keep the duration under 230...If you want more highend power/torque while sacraficing some lowend go mid 230's.... There is no magical cam. Personally, Id also stick with XER lobes for a street driven car. Thats why I did. My car makes 320 rwtq at 2500 rpms and hits peak torque of 400rwtq at 4800. The power peak is 435rwhp at 6300 rpms. This is a 228/228 duration XER cam, 114 +4 LSA...PRC LS6 heads stock valves/stock compression/stock quench and through the exhaust.
I just bought a Fast 90/90 and after I get that installed Im expecting 450rwhp and 410rwtq from this combo, and 600rwhp with the juice.