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For the last couple of months I have been collecting parts for the H/C/I build on my 99 FRC. Previously I added Speed Engineering long tubes, LS6 intake and a base tune. I bought the car with a Borla S-type (original) axle back and a Volant CAI. I sent to car to Speed Inc to have the parts installed and get a dyno tune.
My parts list is:
PRC 2.5 243's
Texas Speed 233/239 cam
FAST 92
LS2 TB
FAST 36# Injectors
Racetronix fuel pump
Summit balancer
Dual springs
Hardened pushrods
Trunion upgrade
Car made 456.3 to the rear wheels. I was extremely happy with that number as I know it isn't a happy dyno. I do wish the car had a higher gear so I started looking at upgrading to a 3rib with a 3.90. I'm also thinking about trying to quiet it down a bit with either a V2 S-type or Corsa sport axle back. Still it's a fun street car at 3100#.
Congrats on the dyno numbers. Like mine I'm sure it's funner then hell to drive.
What size long tubes are you running? I was thinking of swapping to their 1 7/8 headers.
Thanks guys. @badazzsi I have 1 7/8" headers on it.
Awesome thank you. They look like quality headers from the pics. Also I have the corsa sport axle back exhaust it sounds good. I can upload some videos if you wanna hear it. I have a video of me launching it from 2500rpms in my build thread if you wanna hear it as well.
Awesome thank you. They look like quality headers from the pics. Also I have the corsa sport axle back exhaust it sounds good. I can upload some videos if you wanna hear it. I have a video of me launching it from 2500rpms in my build thread if you wanna hear it as well.
They were a breeze it install and 2 years later are still holding up well. The clamps suck so upgrade those. I think I went with Summit brand for new clamps. I will jump over to your thread to check out the video. Corsa seems to be my #1 choice. I had it on my C6 before I went full stealth.
They were a breeze it install and 2 years later are still holding up well. The clamps suck so upgrade those. I think I went with Summit brand for new clamps. I will jump over to your thread to check out the video. Corsa seems to be my #1 choice. I had it on my C6 before I went full stealth.
Thanks for the heads up on the clamps. I just uploaded another video on my thread. It's a cold start with me driving.
Congrats! I have been contemplating a similar build for my 2000 coupe. Can you give me an idea of the labor costs you incurred?
thanks and enjoy your new found HP!
It's a little hard to give you a strictly labor cost. I paid about $3K but that included the dyno tune and the fuel system. I provided most of the parts though. I bought them in stages.
The wheels look good. If they weren't on vettes so much I would probably go that route but I think I might go bc forged for my wheels. Also have you decided on what exhaust you wanna get? By the way how much torque did you make?
Decided to add Texas Speed high flow cats to the x-pipe. I lost ~10 rwhp which is about what I expected. The car is much more enjoyable since I don't reek like exhaust every time I take the car out and it seems to have toned down the drone a little bit. I am still considering adding Ti Z06 mufflers or Corsa Sport to tame it down a bit more. I am also considering sending the FAST 92 and LS2 TB to Tony Mamo for porting to get back some of the HP I lost and hopefully get back over the 450HP mark.
Nice looking curve
Excess gas-stanky can be addressed quite a bit in the tune. Will never be as good as stock due to the cam overlap, but imho many/most cammed cars are running waayyy to rich at idle and low speed.
Decided to add Texas Speed high flow cats to the x-pipe. I lost ~10 rwhp which is about what I expected. The car is much more enjoyable since I don't reek like exhaust every time I take the car out and it seems to have toned down the drone a little bit. I am still considering adding Ti Z06 mufflers or Corsa Sport to tame it down a bit more. I am also considering sending the FAST 92 and LS2 TB to Tony Mamo for porting to get back some of the HP I lost and hopefully get back over the 450HP mark.
Nice! Your numbers are spot on for your mods. My NA build on my '99 was similar to yours with the exception of the injectors and Fast intake. I was on stock injectors and LS6 intake. Car made 28rwhp less than yours.
If you plan on keeping your car NA then the gear swap is an awesome compliment to that cam spec. I ran a 4.10 gear for many years with a 232/236/113+ cam. Car loved that 4.10 gear with that cam. I also ran a 3.90 in my other C5 which was also a better gear IMO than 3.42 but the 4.10 is my favorite. You'll love the gear change 100%. Especially street and slow speed parking lot driving. The 3.42s are too long for most NA builds with a 230+ cam.
However, if you ever plan to go FI the ported Fast is kind of a waste of money and the gear swap may not be the best option. Just something to chew on before pulling the trigger.
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Nice! Your numbers are spot on for your mods. My NA build on my '99 was similar to yours with the exception of the injectors and Fast intake. I was on stock injectors and LS6 intake. Car made 28rwhp less than yours.
If you plan on keeping your car NA then the gear swap is an awesome compliment to that cam spec. I ran a 4.10 gear for many years with a 232/236/113+ cam. Car loved that 4.10 gear with that cam. I also ran a 3.90 in my other C5 which was also a better gear IMO than 3.42 but the 4.10 is my favorite. You'll love the gear change 100%. Especially street and slow speed parking lot driving. The 3.42s are too long for most NA builds with a 230+ cam.
However, if you ever plan to go FI the ported Fast is kind of a waste of money and the gear swap may not be the best option. Just something to chew on before pulling the trigger.
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You are pretty much echoing my thoughts. I was looking into a built 3 rib diff with 3.90 gears as the next mod if I decide to port the intake and TB. Basically that will be the last piece of max effort HP while keeping the car streetable and enjoyable. I already spent $700 to lose 10rwhp but so far it's been worth it as I enjoy the car more. I also will need to upgrade the clutch at some point in the near future and wouldn't mind quieting it down with new mufflers as well.
I kept the LS6 intake that came off the car and have ID1050 injectors from a previous car so IF I went FI I would sell the FAST and run E85. I will still need a stronger diff but a 3.90 might still be a good gear at 700rwhp.
You are pretty much echoing my thoughts. I was looking into a built 3 rib diff with 3.90 gears as the next mod if I decide to port the intake and TB. Basically that will be the last piece of max effort HP while keeping the car streetable and enjoyable. I already spent $700 to lose 10rwhp but so far it's been worth it as I enjoy the car more. I also will need to upgrade the clutch at some point in the near future and wouldn't mind quieting it down with new mufflers as well.
I kept the LS6 intake that came off the car and have ID1050 injectors from a previous car so IF I went FI I would sell the FAST and run E85. I will still need a stronger diff but a 3.90 might still be a good gear at 700rwhp.
I've been debating another gear swap myself. I blew my last 4.10 diff my first pass at Island Dragway in 2021. I put my spare 3.42 3 rib Z06 diff back in same day. A few months later I added a Novi 1500. As a hater of 3.42 gearing in an NA C5...I'm also not a big fan of 3.42 when low speed driving an H/C/FI car. However, when getting in the throttle at 634/568 at the wheels the 3.42 gearing has me shifting in a flash.
The only benefit to a steeper gear swap now is just that real low speed parking lot driving or creeping through my "four wreath community". None of which is why I built my car or take my car out for drives. Otherwise steeper gears are a detractor at the current power level.
Still on the fence I reached out to Chris at ECS just last month for his reccomendation/opinion on swapping the gear. He recommended I stay with the 3.42. Which helped get me over the mental debate I've been having with the man in the mirror.
Just another thing to point out...with H/C/FI my car drives damn near stock with my tune at low RPM. If I granny shift and cruise around it's like a stock C5. It feels way more tame with the FI tune at low speeds than it was just H/C. But when I get after it the thing frigging screams. It's seriously like having two cars in one.
If you stay NA seriously consider the 4.10 over the 3.90. Having done both the 3.42 to 3.90 swap isn't enough of a change to make you feel it was money well spent.
I've been debating another gear swap myself. I blew my last 4.10 diff my first pass at Island Dragway in 2021. I put my spare 3.42 3 rib Z06 diff back in same day. A few months later I added a Novi 1500. As a hater of 3.42 gearing in an NA C5...I'm also not a big fan of 3.42 when low speed driving an H/C/FI car. However, when getting in the throttle at 634/568 at the wheels the 3.42 gearing has me shifting in a flash.
The only benefit to a steeper gear swap now is just that real low speed parking lot driving or creeping through my "four wreath community". None of which is why I built my car or take my car out for drives. Otherwise steeper gears are a detractor at the current power level.
Still on the fence I reached out to Chris at ECS just last month for his reccomendation/opinion on swapping the gear. He recommended I stay with the 3.42. Which helped get me over the mental debate I've been having with the man in the mirror.
Just another thing to point out...with H/C/FI my car drives damn near stock with my tune at low RPM. If I granny shift and cruise around it's like a stock C5. It feels way more tame with the FI tune at low speeds than it was just H/C. But when I get after it the thing frigging screams. It's seriously like having two cars in one.
If you stay NA seriously consider the 4.10 over the 3.90. Having done both the 3.42 to 3.90 swap isn't enough of a change to make you feel it was money well spent.
Kind of cringing reading this, bc I just recently re-purchased a H/C Z06 I sold years ago. Made 448/410. I sold it with a 373 rear, and it was trashed when I got it back, so sent to RPM and had a 3.90 rear built. I love it for H/C, but made an appointment last week to go with an A&A kit, now has me thinking the 390 with the mn12 will be too steep?! From what I recall, a 390 in a Z06 is about the same ratio as a C5 with 410s?
Kind of cringing reading this, bc I just recently re-purchased a H/C Z06 I sold years ago. Made 448/410. I sold it with a 373 rear, and it was trashed when I got it back, so sent to RPM and had a 3.90 rear built. I love it for H/C, but made an appointment last week to go with an A&A kit, now has me thinking the 390 with the mn12 will be too steep?! From what I recall, a 390 in a Z06 is about the same ratio as a C5 with 410s?
Glad you brought your old baby back home where it belongs! The M12 with 3.90 gear will have RPMs between 100 and 375 RPMs higher (depending on speed) than an MN6 with 4.10s. It's not that much of an RPM difference really and at your current power level a really fun gear. But when you have the added torque from the supercharger the steeper gear is going to rev through the gears with a major quickness. Even with some extra RPM from a higher revving cam the 3.42 gear is revving out VERY fast with FI.
Undoubtedly low speed driving will be better with the steeper gear. But otherwise you may find them too short with the added power when you get in the gas. If you mainly cruise around town in your car it could be a good fit for you. Its the times you get after it or bring it to the track that will have you second guessing that gear change.
It's a bit of a catch 22 once FI and well over 500rwtq is part of the equation.
Glad you brought your old baby back home where it belongs! The M12 with 3.90 gear will have RPMs between 100 and 375 RPMs higher (depending on speed) than an MN6 with 4.10s. It's not that much of an RPM difference really and at your current power level a really fun gear. But when you have the added torque from the supercharger the steeper gear is going to rev through the gears with a major quickness. Even with some extra RPM from a higher revving cam the 3.42 gear is revving out VERY fast with FI.
Undoubtedly low speed driving will be better with the steeper gear. But otherwise you may find them too short with the added power when you get in the gas. If you mainly cruise around town in your car it could be a good fit for you. Its the times you get after it or bring it to the track that will have you second guessing that gear change.
It's a bit of a catch 22 once FI and well over 500rwtq is part of the equation.
Thanks! Glad to have to have it back in my hands. It was my first corvette I ever bought, spent a lot of time modding it, and making it my own. It was ironic, I sold my RPM built c6Z06, and 3 weeks later, the owner of the C5 asked me if I wanted to buy it back.
It feels pretty anemic compared to the 628rwhp ls7 I sold. As far as driving, spirited drives, and cruising is all I do, no track days, road or strip. I will see how it goes with the added hp/tq, and if need be, back it down to 342s. Appreciate the feedback!!
09-07-2022, 09:58 AM
Dyno Numbers From My H/C/I FRC
