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One more little tweak


jmxp69

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So do I have this right?

1) It'll make lower boost with the hot air (makes sense)

2) All cars N/A and FI will suffer the same degradation due to heat

3) As it cools, the measured boost and HP will increase. So if I performed no other mods and put it on the dyno in February, I could reasonably expect higher boost and hp output?

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So do I have this right?

1) It'll make lower boost with the hot air (makes sense)

2) All cars N/A and FI will suffer the same degradation due to heat

3) As it cools, the measured boost and HP will increase. So if I performed no other mods and put it on the dyno in February, I could reasonably expect higher boost and hp output?

You got it. Last night when it was 93F outside I was making 11psi. This morning on the way to work it was 75F and I saw 12psi.

Another restriction is the blower intake "dongle". If you went with a cut down radiator and made a 4" intake tube you will see a boost increase as well.

You really needed to get a before the blower dyno numbers in this heat. That way you would be able to see a % increase and not just some inflated numbers from all over the interwebz.

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So do I have this right?

1) It'll make lower boost with the hot air (makes sense)

2) All cars N/A and FI will suffer the same degradation due to heat

3) As it cools, the measured boost and HP will increase. So if I performed no other mods and put it on the dyno in February, I could reasonably expect higher boost and hp output?

You got it. Last night when it was 93F outside I was making 11psi. This morning on the way to work it was 75F and I saw 12psi.

Another restriction is the blower intake "dongle". If you went with a cut down radiator and made a 4" intake tube you will see a boost increase as well.

You really needed to get a before the blower dyno numbers in this heat. That way you would be able to see a % increase and not just some inflated numbers from all over the interwebz.

Well, the ship has sailed on the before blower dyno. That would have been ideal but I've already got the blower on and I'm not taking it off now :) I'm going to work on the assumption that I had 315hp stock.

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Got the car down to the shop and Nic loaded the base tune. He just took off in the car to dial it in a little and then we'll strap it to the dyno. Car already sounds better now that he's configured the computer for 60lb injectors.

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Couple of things for you to watch while I get the pics uploaded:

Last pull on the dyno

Nic did a drive-by for me after the tune. I've never heard my car roll by from the outside before.

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Loaded up and getting chained down for the trip.

1.jpg

Turns out the flat bed driver is a car guy too. We talked about his 64 Chevelle 496 stroker build and my work on the Vette all the way down :)

2.jpg

Nic got the computer connected and a base tune installed pretty quickly. He took it for a few laps around the block to dial it in before putting it on the dyno.

4.jpg

And here it is. I won't lie and say I'm not a little disappointed; however, Nic said the SC is moving a ton of air and we saw sparks coming out the exhaust which indicates the cats are the obstruction. He strongly recommended headers and catless straight pipes. Make sense given the engine is an air pump and while I'm stuffing a lot more in, I've gotta fix it so more can come out.

Anyway, this is probably ~140hp and 100lb/ft over stock. It drives exactly like the chart shows. It starts coming on pretty strong around 2500-3000rpm and just continues getting stronger all the way to redline. 60-90mph on the Interstate is ridiculous in 2nd or 3rd gear. I floored it in second gear after turning a corner and the traction control just screamed for mercy. While a little lower than what I hoped for, this isn't bad for a mod that didn't require me to break a seal on the block. Headers are definitely next, so I'm interested in opinions. ARH or Kooks v2s?

Have to give you props Joe--you called it pretty much to the number. 7lbs of boost, 10 degrees of timing, 91 octane, no meth.

dyno.jpg

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So the addiction begins....

The first few pounds don't cost that much...

But once you're hooked....

Bank accounts beware!!!

Haha.

I'm sure you will have a ton of fun with that. Does OBX make C5 headers? I know a lot of C6 guys run them. They don't cost a fortune since they aren't made in 'Murica. I would ask Joe which headers are the easiest to install also. You could probably just have an exhaust shop make some cat delete pipes for you if you don't want to do headers right now. Then just have Nic turn off the rear o2 sensors.

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So the addiction begins....

The first few pounds don't cost that much...

But once you're hooked....

Bank accounts beware!!!

Haha.

I'm sure you will have a ton of fun with that. Does OBX make C5 headers? I know a lot of C6 guys run them. They don't cost a fortune since they aren't made in 'Murica. I would ask Joe which headers are the easiest to install also. You could probably just have an exhaust shop make some cat delete pipes for you if you don't want to do headers right now. Then just have Nic turn off the rear o2 sensors.

I decline to say what Nic might or might not have done regarding ahem...well...GREAT idea though! :) I wonder if I can get them to install those cat delete pipes.

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joe@cpr.com

To hell with obx headers, they fit like garbage. Kooks, arh, and LG are what we carry. I guess after doing countless supercharger installs I get pretty good at guessing dyno numbers lol.

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Well, you were within 10hp and if my cats weren't messed up, you probably would have been dead on. What do you think about cutting out the cats and putting in straight pipes until I can get the headers done? Headers are definitely the next purchase.

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That is pretty much how my car performed with the similar set-up, when you factor in the 25 deg. cooler temp. I had less restriction with the headers and high flow cats, which messed with the boost numbers, so I can't remember what it was at. (~6-7 psi I believe)

Do not go with high flow cats, the S/Cs tend to melt the insides from the heat. Mine were so restricted after 500 mi. that the headers were glowing red at idle. Burned some valves from that also. Good excuse to change all the valve out though.

The downside to running with no cats is that your exhaust will smell like it is running ultra rich at idle. I have to back my car out of the garage and shut the door to let it warm up in the winter, or it will smell up the whole house. E85 will take care of that though.

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You could also just take your cats off and hollow them out. Then reinstall them. E85 smells so nice. I'm bummed I don't have it next to the plant anymore.

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Do not go with high flow cats, the S/Cs tend to melt the insides from the heat. Mine were so restricted after 500 mi. that the headers were glowing red at idle. Burned some valves from that also. Good excuse to change all the valve out though.

The downside to running with no cats is that your exhaust will smell like it is running ultra rich at idle. I have to back my car out of the garage and shut the door to let it warm up in the winter, or it will smell up the whole house. E85 will take care of that though.

Yeah, that's a problem for me. I don't want to run around in my vette smelling gas. I want cats just to reduce that smell.

You could also just take your cats off and hollow them out. Then reinstall them. E85 smells so nice. I'm bummed I don't have it next to the plant anymore.

I haven't looked..is the cat section of pipe bolt-on or will they have to be cut/welded (or clamped)?

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Do not go with high flow cats, the S/Cs tend to melt the insides from the heat. Mine were so restricted after 500 mi. that the headers were glowing red at idle. Burned some valves from that also. Good excuse to change all the valve out though.

The downside to running with no cats is that your exhaust will smell like it is running ultra rich at idle. I have to back my car out of the garage and shut the door to let it warm up in the winter, or it will smell up the whole house. E85 will take care of that though.

Yeah, that's a problem for me. I don't want to run around in my vette smelling gas. I want cats just to reduce that smell.

You could also just take your cats off and hollow them out. Then reinstall them. E85 smells so nice. I'm bummed I don't have it next to the plant anymore.

I haven't looked..is the cat section of pipe bolt-on or will they have to be cut/welded (or clamped)?

if you don't want the unleaded rich smell, then you shouldn't hollow out your cats. If you search the big forum, you'll pretty much see that almost everyone who has a SC has either not installed cats, or melted them. You might talk to Joe about getting some ZR-1 or other SC OEM cast off cats to use. I read that some expensive aftermarket cats (not LGs) will last a few years, but eventually they all seem to melt/clog and you have to keep replacing them. My issue with that is, you may not know when that happens, until something bad show up (e.g. my burned valves).

One of the drawbacks of generating heat with the SC. (unleaded smell, E85, OEM restrictions, choose one). Welcome to the, as your title says," One more little tweak" club. I started off just where you are "just the SC, I don't need anymore power, can't get it to the ground anyways" Ha!

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I figured hollowing out the cats would give me an idea of what a catless x-pipe would be like to live with. It would be a cheap trial before shelling out the $$ for the full exhaust.

I really do see where this is going. I sold my take-off thinspokes to another Vette guy today and when he was in my garage checking out my car, he asked if I'd start it so he could hear the exhaust/blower. After leaning down and listening at the pipes, he popped up and said, "you know your cats are obstructed right?" lol...yup...Nic told me yesterday. I also went for some backroad driving today and my clutch doesn't love a hard launch. I need to get it to grab first, then it's fine. Joe and I have discussed internals/heads/cam strategies too, so I guess it's time to just plan and execute.

- May go ahead and pull trigger on exhaust now.

- Scheduling headers/x-pipe install with Joe tomorrow.

- Clutch, internals, heads, cam later.

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Try to listen to all of the exhausts in person before you buy. If you can get test rides, that will be better. My Magnaflow sounds great at idle, great when you rev. it, but it drones loudly at 1400 - 1700 RPM, exactly where you cruise at on the freeway (~ 60-75 mph). Also headers, cats and cams change the loudness characteristics of the exhaust big time. Joe can guide you in this area, but nothing beats hearing it for yourself. One person's great sound, is another person's obnoxiously loud.

One more suggestion. The boost a pump, I'm assuming you have one, has a fuse on it. It is located in the rear fender well. I got stranded during the last Corvette event in Goodyear, due to this fuse blowing. I had no way to remove the rear wheel to get to it, so I had to have it towed all the way back to Mesa, just to remove the wheel and change a fuse. I would suggest that you extend the fuse to your trunk area for access.

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Just got off the phone with Joe. It's looking like next week for header install. I went with Kooks and hi-flow catless x-pipe. Also going down 1/10th on the pulley to 3.48" Found it at Summit.

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Try to listen to all of the exhausts in person before you buy. If you can get test rides, that will be better. My Magnaflow sounds great at idle, great when you rev. it, but it drones loudly at 1400 - 1700 RPM, exactly where you cruise at on the freeway (~ 60-75 mph). Also headers, cats and cams change the loudness characteristics of the exhaust big time. Joe can guide you in this area, but nothing beats hearing it for yourself. One person's great sound, is another person's obnoxiously loud.

One more suggestion. The boost a pump, I'm assuming you have one, has a fuse on it. It is located in the rear fender well. I got stranded during the last Corvette event in Goodyear, due to this fuse blowing. I had no way to remove the rear wheel to get to it, so I had to have it towed all the way back to Mesa, just to remove the wheel and change a fuse. I would suggest that you extend the fuse to your trunk area for access.

Joe has been very helpful discussing options. I went with Kooks and their hi-flow cats.

Great call on the BAP. I really didn't like seeing a fuse tucked away like that one is. How did you know the BAP went out? How does one know the BAP is even working? That's been a nagging question in my mind from the moment I installed it.

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I didn't know it was the BAP, but we had checked 2 fuses and a relay under the hood. A call to Joe, brought it down to the BAP fuse, BAP failure or fuel pump failure. Got it back to the shop and verified it was the fuse.

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Did you ever find out what caused the fuse to blow? You know...where there's smoke, there's fire. I don't like blown fuses, they're normally a precursor to something more exciting.

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