Reducing exhaust fumes from cammed L77.

[Jeda]

if u get it tuned again then i can show u some settings to help out get them to adjust it will at least get your idle better and it helps with low end torque also and drivability also

Thanks man, I'll message you before I take it in to get the details of the what settings to alter. Won't be for a while as I'll do the exhaust first

 

[Jeda]

APS, twin city dyno tuning (Brett is one of the best in the country to my understanding - worked at G&D and HPF when their reputations were at the top of the game), LS1pwr among others.

Just make sure you do your research before committing to a tuner.

With a cam they will often smell, and there’s not always much you can do about it. If the engine is happiest at 12:1 idle afr and that gives best off idle transition, thats where you want it. All engines will be different.

Of course have some 200 or 400 cell cats fitted first prior to retuning if it’s a real concern to you.

Thanks for the reply, EYY.
In the mid 90's I had a cammed vc and vk, and I don't remember them stinking this much.

The only time it doesn't stink is when I'm running a tank of e85. But the trade off is I'll get around 150km from a full tank, and that's babying the thing.
On a full tank of 98, lucky to get 270km out of it as it is now.
Really think a retune could make the whole car better.

I will try and find some 400 cell cats and get them installed then get it retuned.

 

[vr304]

Damn that’s poor fuel economy!! No wonder it’s fumey, definitely needs the tune looking at mate, I’d say that’s where the majority of issue is

 

[losh1971]

Agree that is really bad economy. I get around 16-17lph to work and back, which is a mixture of hills, highway and city, On the mainland highways I can get 11lph or better.
I'd be going to a different tuner. Mine was tuned in Melb before I bought it and the tune was botched. I had it redone locally and the difference was massive.

 

[Jeda]

Agree that is really bad economy. I get around 16-17lph to work and back, which is a mixture of hills, highway and city, On the mainland highways I can get 11lph or better.
I'd be going to a different tuner. Mine was tuned in Melb before I bought it and the tune was botched. I had it redone locally and the difference was massive.

It's not great. For example, when I take off slowly from a stop, it's showing 39.9Lt per 100km on the instant fuel usage display. 39.9L/100 is the maximum the display can read, so who knows how much its actually using.
If I'm on the freeway, and that's a rare event in itself, it'll get down to about 12L/100 in 6th on a flat surface, so not too bad. Any incline and it'll jump into the high teens at least. That's using cruise control too.

I didn't modify it for economy, I knew the trade-off in power would be increased fuel consumption.
Just want to be able to start the car without first making sure the wife and kids aren't within 30 feet.

Had a look this morning and magnaflow make some 400cpi cats with 3 inch inlet/outlets. They have a ceramic substrate though. Not sure if metal ones are available in this size.

 

[dassaur]

It's not great. For example, when I take off slowly from a stop, it's showing 39.9Lt per 100km on the instant fuel usage display. 39.9L/100 is the maximum the display can read, so who knows how much its actually using.
If I'm on the freeway, and that's a rare event in itself, it'll get down to about 12L/100 in 6th on a flat surface, so not too bad. Any incline and it'll jump into the high teens at least. That's using cruise control too.

I didn't modify it for economy, I knew the trade-off in power would be increased fuel consumption.
Just want to be able to start the car without first making sure the wife and kids aren't within 30 feet.

Had a look this morning and magnaflow make some 400cpi cats with 3 inch inlet/outlets. They have a ceramic substrate though. Not sure if metal ones are available in this size.

I've looked into this. No metal ones available. Check the body size of the cat you are looking at - I think at 400CPI yo uwould want 5" body - which might be a problem with ground clearance if you have long tubes.

 

[vr304]

It's not great. For example, when I take off slowly from a stop, it's showing 39.9Lt per 100km on the instant fuel usage display. 39.9L/100 is the maximum the display can read, so who knows how much its actually using.
If I'm on the freeway, and that's a rare event in itself, it'll get down to about 12L/100 in 6th on a flat surface, so not too bad. Any incline and it'll jump into the high teens at least. That's using cruise control too.

I didn't modify it for economy, I knew the trade-off in power would be increased fuel consumption.
Just want to be able to start the car without first making sure the wife and kids aren't within 30 feet.

Had a look this morning and magnaflow make some 400cpi cats with 3 inch inlet/outlets. They have a ceramic substrate though. Not sure if metal ones are available in this size.

That’s ridiculously poor fuel economy even for a cammed LS mate you definitely need to get the tune looked at, I’d be doing that before you worry about the exhaust

 

[Phillbo]

I'm running an L77, DoD delete, 1-7/8 headers, hf cats with 2.5" exhaust. Cam is a 224/232 608/608 114 LS. Was extremely happy with the conversion but very very dissapointed with the crap tune. On cold start my eyes would burn with the fumes of unburnt fuel. Idle was awful and the fuel economy was pathetic - I could not get more than 300ks' from a tank with highway economy around 18ltrs/100k's

After investing in HPTuners and working with an experienced tuner, my car now feels and drives so much better. Lower to mid power is better (fitting a wideband shortly for upper power). My eyes now don't dissolve on start and economy is through the roof....12 to 14ltrs/100 around town with highway hovering around 8.5 to 9.5.

There are many tuners out there who seem to know very little as my supposed mafless tune didn't even have the speed density patch applied ....really!

Oh and if anyone want's to know who not to go to for a tune then pm me.

 

[Jeda]

I've looked into this. No metal ones available. Check the body size of the cat you are looking at - I think at 400CPI yo uwould want 5" body - which might be a problem with ground clearance if you have long tubes.

Yeah 5" round might not leave much ground clearance.

 

[RevNev]

The 100 cell cats may as well be gutted standard cats. They do the same job. The only difference is after market cats are easy to spot by anyone wanting to issue a defect notice.

Pacemaker an SA company made the shorty header similar to the HSV 340 headers to comply with SA's exhaust mod rules retaining the stock cats in the original location. Pacemaker shorty or 340 headers with piped cats that make nearly the same power as long tubes and 100 cells on a stock or mild cam engine, will pass a Rego inspection where the long tubes and aftermarket cats get a defect notice.