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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Thanks Hib for taking an interest & helping me learn.
You're welcome. Glad to be of service.
BTW, I noted your car is a '13. You might want to look at backdating the exhaust to a 2-cat system off an '11. I did that on my '12 and gained a little power and ended up with the car sounding better.
BTW, I noted your car is a '13. You might want to look at backdating the exhaust to a 2-cat system off an '11. I did that on my '12 and gained a little power and ended up with the car sounding better.
I know you're a serious AutoXer so...have fun!
I am thinking that, if I find one at a decent price. Should be some as a lot put a whole system on.
I did notice on mine there is NOT an H connection. Don't know what year it changed but mine is like the after market ones with the sides of the 2 pipes sliced open and welded right up.
I am thinking that, if I find one at a decent price. Should be some as a lot put a whole system on.
I did notice on mine there is NOT an H connection. Don't know what year it changed but mine is like the after market ones with the sides of the 2 pipes sliced open and welded right up.
Admittedly, as this started as a gasoline thread, so we're getting even farther off-topic here, as this was originally a gasoline thread but...
GM introduced an X-pipe mid-section in '09 on ZR1 and, in '11, replaced the H-pipe with the X-pipe on ZO6.
Unfortunately, the exhaust-backdate mod is a bit pricey and labor intensive. Because GM changed the connections between the cat outlets and mid-section inlets, to do that mod on a '12 or '13, you need cats from either an '09-'11 ZR1 or an '11 ZO6. You also need the exhaust mid-section from an '09-'11 ZR1 or an '11 Z06. You replace both cats and the mid-section but keep the lower restriction '12/'13 mufflers. On my car the mod was worth 11-hp and 11.6 lbs/ft torque at their respective peaks. Those numbers are SAE-corrected.
Re: the cat conversion, I think a good independent muffler shop could just cut out the 2nd set of cats & put some "test pipe" sections in. Maybe even I could do it, hehe.
They are pretty small cats , not sure the power gain would be worth the effort. I am NOT doubting your numbers as I know you are meticulous in the work you do, that seems like a LOT of power by deleting those 2 little cats. Were you surprised at the gain?
Re: the cat conversion, I think a good independent muffler shop could just cut out the 2nd set of cats & put some "test pipe" sections in. Maybe even I could do it, hehe.
They are pretty small cats , not sure the power gain would be worth the effort. I am NOT doubting your numbers as I know you are meticulous in the work you do, that seems like a LOT of power by deleting those 2 little cats. Were you surprised at the gain?
Because of aggressive enforcement and very high fines, it's quite rare to find anyone who will install "test pipes" in place of cats on a car licensed for the street.
Your welding will need to look like stock because, when a inspector look under the car, depending on how sharp-eyed and how much of a conformist he/she is, if they can tell you cut the second set of cats out, they might flunk you.
I'd think if you were a good welder and were using the same kind of tubing, you could do it that way.
Because those cats were small and potentially restrictive, along with understanding what GM did to reduce restriction elsewhere in the system for '12 and '13 to make sure the LS7 could still hit the 505 mark, I expected a gain but not quite that much. I was looking for 7-8.
Last edited by Hib Halverson; 05-21-2018 at 02:23 PM.
This debate and some of the ignorant comments I see on this site, as well a casual conversation with others, is a pet peeve of mine. I have wonderful 90 octane "premium" fuel. The second option is 89, then of course; 87. I have spent quite literally, 100's of hours experimenting with fuels, additives (including those found in the hardware store paint section), blending race fuels, methanol, water injection, ect. And, I also tune my own vehicles and a few friends from time to time.
I am glad Hib weighed in on this subject. His position is the correct one. The notion that the ECM will resolve inadequate fuel requirements is extremely misleading. It will only do what it can, and it does have its limits. Unless you have actually logged KR with a tank of crappy 91 or 90 octane fuel, (and assuming you know what it is you are looking at), you ought to just refrain from saying anything.
Yes, there is a "low octane" spark table, and a "high octane" spark table. I'll post a pic of both below. Take note of the values found in each table at the respective cell. However, the ECM, does not have a switch that flips back and forth between the two tables. The ECM always references both. It monitors KR over time and learns a multiplier to use when it sees KR again in order to know just how much spark to pull. You can actually see this learning if you log the PID: Knock Learn Factor. This enables the ECM to know how much spark to pull if the KR sensors are activated. It also works with another KR table called "Burst Knock". Burst knock retard is an aggressive function that will pull spark before any KR is seen.
(snip) Unless you have actually logged KR with a tank of crappy 91 or 90 octane fuel, (and assuming you know what it is you are looking at), you ought to just refrain from saying anything.(snip)
"Michael D" gets the Tuesday morning "Beacon of Reality Award".
05-19-2018, 07:28 PM
