So soon I'll be installing the LS3 in my AK427, so what are my IVA compliant side pipe options?
Regards
Phil
Don't quote me on it, check in the IVA manual first. It use to be about 75% of the engine max power = lower than something like 95Db, Best person to ask for advice is Anthony Hale @ Absolute Horse Power or Crendons.
He has just put a couple of AKs through the IVA. As its an LS3 you will need cats for the emissions check.
I've just been through IVA with side pipes
The regs are 99dB at 75% Max revs or at max Hp rpm. Reading to be taken 200mm off ground or at exit height which ever is higher and at 500mm from exit at 45 degrees to it.
I have a set of DB replica side pipes. But these needed an end cap on for the radius and dB killers in them to get under the limit. Mine came in at 98.6dB so by the skin of its teeth!
I'm not sure which systems are IVA compliant off the shelf though.
Cheers
Greg
Quote from: Austin21 on Jul 16, 2023, 03:00 PMI've just been through IVA with side pipes
The regs are 99dB at 75% Max revs or at max Hp rpm. Reading to be taken 200mm off ground or at exit height which ever is higher and at 500mm from exit at 45 degrees to it.
I have a set of DB replica side pipes. But these needed an end cap on for the radius and dB killers in them to get under the limit. Mine came in at 98.6dB so by the skin of its teeth!
I'm not sure which systems are IVA compliant off the shelf though.
Cheers
Greg
Thanks Greg,
Do your side pipes come with cats too? What engine are you running? I know I will need cats but just looking about for different options at the moment.
Regards
Phil
Quote from: Peato40 on Jul 16, 2023, 03:44 PMThanks Greg,
Do your side pipes come with cats too? What engine are you running? I know I will need cats but just looking about for different options at the moment.
Regards
Phil
Hi Phil
Ah yeah er what this thing about CAT's ;D ;D
My engine is a 1973 Chevy 350 block bored and stroked out to 383, but because of the age I don't need CAT's it's a non-metered emissions test thankfully.
That said I would be possible to fit some just after the merging section but that's not the best place for them they need to run HOT to work efficiently so as soon after the headers the better.
Cheers
Greg
Thanks Greg,
CATS will be a must for me, and I believe some are mounting them inside the side pipe, but as you say, might not be performing at their optimum if they aren't getting hot enough. So I thought it might be good to ask the Cobra community about their experiences.
Regards
Phil
Here are a few photos of my side pipes and cats on my AK, with an LS3
The only thing I would really change is where the cat meets the 4 into one collector, maybe should have put flanges on it, rather weld them.
Also the cast manifolds should have had the recessed grooved face machined flat to give a better face seal to the J pipe 2 bolt flange. Had to fit a crush gasket to take up the depth.
Side pipe 1.jpg
side pipe 2.jpg
Side pipe 3.jpg
Crush gasket.jpg
Thanks Mike,
AK Supply?
Regards
Phil