C5 z06 hp mods?
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Joined: Nov 2020
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From: California.
C5 z06 hp mods?
Hello I’m wanting to start to mod my car and was wondering what kind of intake, head, cam and exhaust would be best to reach the most amount of hp whole staying N/A while trying to be able to pass a visual on the smog inspection though not important for me(hot smog is also doable) What are things I can get away with from those that have experience with smog here. I do want to have a lot more mid to high range torque and an aggressive and lumpy cam as well. Thanks In advance.
Melting Slicks
Joined: Dec 2018
Posts: 2,663
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From: Orange County, CA
I don't have specific recommendations, but want to comment on CA smog stuff:
Would you consider an A&A supercharger kit? They offer CA-legal kits (including tunes) so you don't have to hassle with anything at smog time.
https://aacorvette.com/shop/product/c5-supercharger/
We also offer CARB emissions compliant systems for the C5 Corvette. Please call or email for emission compliance specifics.
- CA smog test equipment now checks for modified tunes, which of course you would need a modified tune if you do the sort of work you're proposing.
- HOWEVER, the C5 is old enough that they aren't able to determine if the tune is stock or modified. So you get a free pass on having a tuned C5Z. Guys have reported failing smog on tuned C6Z models.
- If you want to be guaranteed to pass visual legitimately, you NEED to have the following parts stock/original:
- catalytic converters: I think your C5Z is an '03, so you have 2 factory cats. A smog test location who knows what they're doing will check the markings on the cats to make sure they're correct.
- there may be CARB-approved aftermarket cats, but those would have a CARB EO # embossed on the cats.
- for a smog test where they "look the other way" on visual, any cats (or lack thereof) will do if your tune properly accommodates them.
- air intake: only stock air intake or CARB-approved intake (i.e. one that you have a CARB EO # for) will pass.
- vacuum system needs to be original
- AIR system needs to be intact & functional
- I'm fuzzy on the legality of a catch can system, but a legit smog shop may turn you away because they may assume the car is further modified.
- no aftermarket gauges... this too could suggest the car is further modified.
- catalytic converters: I think your C5Z is an '03, so you have 2 factory cats. A smog test location who knows what they're doing will check the markings on the cats to make sure they're correct.
Would you consider an A&A supercharger kit? They offer CA-legal kits (including tunes) so you don't have to hassle with anything at smog time.
https://aacorvette.com/shop/product/c5-supercharger/
We also offer CARB emissions compliant systems for the C5 Corvette. Please call or email for emission compliance specifics.
Thread Starter
Advanced
Joined: Nov 2020
Posts: 79
Likes: 7
From: California.
I don't have specific recommendations, but want to comment on CA smog stuff:
Would you consider an A&A supercharger kit? They offer CA-legal kits (including tunes) so you don't have to hassle with anything at smog time.
https://aacorvette.com/shop/product/c5-supercharger/
We also offer CARB emissions compliant systems for the C5 Corvette. Please call or email for emission compliance specifics.
- CA smog test equipment now checks for modified tunes, which of course you would need a modified tune if you do the sort of work you're proposing.
- HOWEVER, the C5 is old enough that they aren't able to determine if the tune is stock or modified. So you get a free pass on having a tuned C5Z. Guys have reported failing smog on tuned C6Z models.
- If you want to be guaranteed to pass visual legitimately, you NEED to have the following parts stock/original:
- catalytic converters: I think your C5Z is an '03, so you have 2 factory cats. A smog test location who knows what they're doing will check the markings on the cats to make sure they're correct.
- there may be CARB-approved aftermarket cats, but those would have a CARB EO # embossed on the cats.
- for a smog test where they "look the other way" on visual, any cats (or lack thereof) will do if your tune properly accommodates them.
- air intake: only stock air intake or CARB-approved intake (i.e. one that you have a CARB EO # for) will pass.
- vacuum system needs to be original
- AIR system needs to be intact & functional
- I'm fuzzy on the legality of a catch can system, but a legit smog shop may turn you away because they may assume the car is further modified.
- no aftermarket gauges... this too could suggest the car is further modified.
- catalytic converters: I think your C5Z is an '03, so you have 2 factory cats. A smog test location who knows what they're doing will check the markings on the cats to make sure they're correct.
Would you consider an A&A supercharger kit? They offer CA-legal kits (including tunes) so you don't have to hassle with anything at smog time.
https://aacorvette.com/shop/product/c5-supercharger/
We also offer CARB emissions compliant systems for the C5 Corvette. Please call or email for emission compliance specifics.
.
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St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23
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Second on the A&A kit. I also live in California and have one on my Z06, all Carb legal and the car made 570rwhp/510rwtq on a basically stock ls6, upgraded a few things while the supercharger was being done like the clutch and torque tube, PAC valve springs, CHE trunnions, ATI harmonic balancer and pin kit, trans/dif brace, etc etc, mainly because its my daily and it needs to be as solid and reliable as possible, and so far so good, thing runs awesome and pulls hard as hell, next upgrde is definitely gunna have to be better tires haha
Last edited by Eric_who; Oct 17, 2022 at 02:08 PM.
Thread Starter
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Joined: Nov 2020
Posts: 79
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From: California.
Second on the A&A kit. I also live in California and have one on my Z06, all Carb legal and the car made 570rwhp/510rwtq on a basically stock ls6, upgraded a few things while the supercharger was being done like the clutch and torque tube, PAC valve springs, CHE trunnions, ATI harmonic balancer and pin kit, trans/dif brace, etc etc, mainly because its my daily and it needs to be as solid and reliable as possible, and so far so good, thing runs awesome and pulls hard as hell, next upgrde is definitely gunna have to be better tires haha
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From: California.
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awesome that’s a good amount of power and in the range of what I’ve wanted to get. How much noise do you get from the supercharger or is it pretty quiet? What tires do you think of getting I currently have the continental extreme contact sports and like them but with a supercharger I’d imagine something more grippy would be needed. Thanks for the reply!
As far as tires, I'm gunna try and get some Toyo R888r's or some comparable Nitto's. Right now it just has some Sumitomo tires on it that came with the car when I bought it a year ago, and it can now easily rip them loose
Race Director
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I installed this intake years ago. We installed it while the vehicle was still strapped to dyno after a base run on completely stock C5Z. It picked up 13hp/11torque. No ram air effect since only using cooling floor fan in front of dyno. This is now discontinued but perhaps will be available soon or may be something similar on the market. All of my other mods are not street legal my any means. 
https://www.corvettecentral.com/c5-9...fair-intake%2f
https://www.corvettecentral.com/c5-9...fair-intake%2f
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St. Jude Donor '05
Are you aware the latest revision of Cas "cant have fun with cars" smog rules are OEM tune only? Cant even mess with the trans.
Visual, you probably know everythings gotta be there..they ck the # stamped on the cats has to be a "ca" one also.
Hear there are a few things you can do where the stock tune can compensate a little.....the CARB legal supercharger kits should pass but not sure if they are getting rejected or not. So much for considering a newer vette for the future
Visual, you probably know everythings gotta be there..they ck the # stamped on the cats has to be a "ca" one also.
Hear there are a few things you can do where the stock tune can compensate a little.....the CARB legal supercharger kits should pass but not sure if they are getting rejected or not. So much for considering a newer vette for the future
Melting Slicks
Joined: Dec 2018
Posts: 2,663
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From: Orange County, CA
Also from everything I've come across, the C5 (and similar era cars) aren't affected by the latest CARB tune checksum verification, so we shouldn't have an issue with tuned C5s (provided all the readiness stuff is intact).
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Joined: Nov 2020
Posts: 79
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From: California.
I installed this intake years ago. We installed it while the vehicle was still strapped to dyno after a base run on completely stock C5Z. It picked up 13hp/11torque. No ram air effect since only using cooling floor fan in front of dyno. This is now discontinued but perhaps will be available soon or may be something similar on the market. All of my other mods are not street legal my any means.
https://www.corvettecentral.com/c5-9...fair-intake%2f
https://www.corvettecentral.com/c5-9...fair-intake%2f
Thread Starter
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Joined: Nov 2020
Posts: 79
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From: California.
OP has a Z06 so I don't think the trans comment applies.
Also from everything I've come across, the C5 (and similar era cars) aren't affected by the latest CARB tune checksum verification, so we shouldn't have an issue with tuned C5s (provided all the readiness stuff is intact).
Also from everything I've come across, the C5 (and similar era cars) aren't affected by the latest CARB tune checksum verification, so we shouldn't have an issue with tuned C5s (provided all the readiness stuff is intact).
Thread Starter
Advanced
Joined: Nov 2020
Posts: 79
Likes: 7
From: California.
Are you aware the latest revision of Cas "cant have fun with cars" smog rules are OEM tune only? Cant even mess with the trans.
Visual, you probably know everythings gotta be there..they ck the # stamped on the cats has to be a "ca" one also.
Here there are a few things you can do where the stock tune can compensate a little.....the CARB legal supercharger kits should pass but not sure if they are getting rejected or not. So much for considering a newer vette for the future
Visual, you probably know everythings gotta be there..they ck the # stamped on the cats has to be a "ca" one also.
Here there are a few things you can do where the stock tune can compensate a little.....the CARB legal supercharger kits should pass but not sure if they are getting rejected or not. So much for considering a newer vette for the future
Race Director
Joined: Oct 2000
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From: N. Alabama
That is correct. Without the ram air effect of traveling at speed while strapped to the dyno it still showed quite an improvement for not much money - relatively speaking. Those initial improvements of 13hp are the cheapest you will ever find. As the HP improvements stack up they get a lot more expensive per/hp. With speed the ram air effect from the shroud should yield a few more.
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