Finally getting my ZR-1 back from Corey's!!!

[EvanZR1]

On the flight down right now to pick up the Z from Corey Henderson's. Following is a brief list of all the work that was done:
OBX Long Tube headers installed
Fuel Injectors installed (from Fuel Injector Connection)
4.10 speedo gears installed
C4 beam plates
Removed secondary throttle blades
new plugs
Updated top end port work
Dyno tune

Final numbers were 360RWHP, which while not earth shattering is way better than the 300RWHP that I was getting. Corey said it didn't look like the secondaries had been working in quite a while. He also said the he would guess that I could probably gain another 20HP with a better flowing exhaust (currently have a Borla) and maybe a 160 thermostat. I was also thinking that I should probably MAT sensor relocation too. He said he was about 2.5 degrees short of where he normally can set the timing to without knock. I didn't have time to really talk with him in depth as he was finishing up and getting ready to go to BG. For any of you interested in OBX headers, make sure you ask him his opinion if you are there. If not, I will request a full email opinion on them and post it on here later.

Can't wait to get there and drive the car. Should definitely be a lot of fun now! :)

[Kevin]

please request an email from him as i won't be able to make it to bg this year

[EvanZR1]

Already requested. His initial comment was that they took a little "tweaking" to fit right. Also, he's not sure how much of the power I'm leaving on the table is the headers and how much is the Borla exhaust. My guess is the Borla as it really constricts before going into the resonator.

[PhillipsLT5]

Corsa time

[Kevin]

Corsa time

i think you meant b&b

[tf95ZR1]

It's the Borla resonator that is restricting.
Switch it out for a B & B X-pipe.
You will gain the HP.
How do I know.........

[PhillipsLT5]

I think you may get drone from B&B
Thats why I like the Corsa, no drone

[EvanZR1]

I think I'm going to try replacing the resonator with an x-pipe first and see what that does. It's a whole lot cheaper than a completely new exhaust.

[xlr8nflorida]

I think I'm going to try replacing the resonator with an x-pipe first and see what that does. It's a whole lot cheaper than a completely new exhaust.

I have a good amount of HP. I don't think you are leaving anywhere near 20 hp on the table at the 360hp level. Yes, the Borla restricts at the resonator. However, it sounds good if you like fairly quiet and no resonance. I hate resonance.

The most you are leaving on the table is 5-10 hp on account of the resonator. You can modify your existing reasonator or get an LT-4 resonator. The X pipe will make resonance.

Headers definetly give you 20hp and with a good exhaust you are golden.

To me anyway, unless its 20HP increase or more, the seat of the pants dyno is not affected.

I understand maximizing HP especially cheap hp. Just keep in mind there are trade offs.

I think you can gain 20hp by switching from Borla to B&B which is a bigger less restrictive system and also much louder with more rumble.

The exhaust claims I think are overstated. When the Borla came out in 1990, I have an ad that came from a reputable shop in Florida, I think it was in corvette fever, it says 40 HP increase from exhaust over stock - I'm sorry no way do I believe it. I think half the time you have to cut the claims in half in most people's applications.

Good luck do your research, I have thought about the X pipe as well and asked about it in the past. Most concur X pipe equals resonance. I am happy at my HP level so I have decided I don't need the extra 5-10hp.

I have thought about modifying my resonator or switching it out but not sure how that would turn out in the end. Marc Haibeck can give you more information on it, I think he even has an article about it.

I am not a big fan of the borla tips and how they hang. I have found a few nice examples of B&B tips and have thought about changing them out. I just need to find a good welder and an exhaust shop I can trust.

The Borla gets alot of bad press but I like it. It's more of a "sleeper exhaust" and does not have drone. I have heard all the others. The one that appeals to me is the B&B but sometimes I think it is too redneck for my tastes. It sounds nasty and like a racecar but as I get older, I like a more understated exhaust. Maybe its all the imports with fart can exhausts that turned me off to the loud exhausts.

Good Luck

[EvanZR1]

Hmm, might have to try an LT4 resonator. I really don't like drone. My 92 LT1 had no mufflers and an x-pipe, and it was a little too much.

[-=Jeff=-]

I have a good amount of HP. I don't think you are leaving anywhere near 20 hp on the table especially at the 360hp level. Yes, the Borla restricts as the resonator. However, it sounds good if you like fairly quiet and no resonance. I hate resonance.

The most you are leaving on the table is 5-10 hp on account of the resonator. You can modify your existing reasonator or get an LT-4 resonator. The X pipe will make resonance.

Headers definetly give you 20hp and with a good exhaust you are golden.

To me anyway, unless its 20HP increase or more, the seat of the pants dyno is not affected.

I understand maximizing HP especially cheap hp. Just keep in mind there are trade offs.

I think you can gain 20hp by switching from Borla to B&B which is a bigger less restrictive system and also much louder with more rumble.

The exhaust claims I think are overstated. When the Borla came out in 1990, I have an ad that came from a reputable shop in Florida, I think it was in corvette fever, it says 40 HP increase from exhaust over stock - I'm sorry no way do I believe it. I think half the time you have to cut the claims in half in most people's applications.

Which Borla do you have? I found with my Borla Challenge system I was getting resonance, granted not anything near like B&B but it was there and it was annoying. It was mostly noticeable in the normal range 1500-2000rpm, but with the windows up and AC on.

B&B is louder, magnaflow has more drone then my borla does.

the Corsa has none or next to none with headers. Each person has a different tolerable level for resonance, some more then others

So far I like my Corsa, it is louder then borla the resonance is almost not there

[xlr8nflorida]

From M. Haibeck:

The difference between a stock system on a
93 and straight pipes is about +18 HP

18HP / 5 PSI = About 3.5 HP/PSI of back pressure
reduction

A case in point. The back pressure on a Borla 2.5
inch system is 1.5 psi at peak power.

5 PSI – 1.5 PSI = 3.5 PSI X 3.5 HP/PSI = +12 HP
The bottom line is that there is not too much of a
power difference between aftermarket exhaust
systems.

There is however, a big difference between how
they sound. Let your ears be your guide.

Someone else can pipe in or I'll check my emails. I think it was an article in the newsletter that discusses borla resonator and modifying it or switching to LT4 resonator.

If the truth were known, I think you are closer to losing 5hp then 10hp as a result of the resonator. I can't even really tell the HP difference when the cats are removed. I doubt you would feel much if you went to X pipe, think it would be negligible.

Good Luck

[xlr8nflorida]

Which Borla do you have?

To be honest, I'm not even sure. I think its the first system Borla ever had for ZR-1.

Here is a pic:

http://i159.photobucket.com/albums/t150/90koth/A4.jpg

[tf95ZR1]

http://i159.photobucket.com/albums/t150/90koth/A4.jpg

That is one great looking car...

:saluting:

[EvanZR1]

That's what I have.

[-=Jeff=-]

That's what I have.

Both the Regular system and Challenge system look the same but the difference is the Challenge system uses 2.75" pipes instead of 2.5" pipes

I do think the Resonator and mufflers are the same between systems.

[EvanZR1]

Mine's only 2.5". I actually have a 2.75" x-pipe I was going to have Corey put on, but he said the exhaust that's on there is only 2.5

[EvanZR1]

Well, so much for getting my car back. I was just driving along normally, when the car just started running really rough and blowing smoke. Was not on it hard or running it up to red line, and had been running fine before that. Limped it home and will let it cool off so I can take a look at it. So far symptoms are:
running rough, has a loud ticking, is blowing smoke and there is an oil leak on the driver's side dripping onto the header. Something else that was weird is that it would occasionally run better briefly on the drive home (under light acceleration over about 2,000rpm).

The ticking sounds like when I had a header gasket blow out on my LT4 Firehawk, but that did not cause rough running like this. I'd think a burnt/shorting plug wire, but they don't go anywhere near the headers. Maybe a fouled plug?? But what about the smoke?

Needless to say I'm really irritated at this point.

[sammy]

i came up with a system that dropped my et by 2 tenths and gained 1.7 mph at the strip over the corsa . my white car is a callaway 475 s natural zr1 with headers . the nice thing is its as quiet as the corsa at cruise. and has a very nice tone when your on it . it cost me 400 for everything . i started with a stk zr1 exhaust .built a ladder style crossover ,got rid of the resonator (put in sections of 23/4 pipe) then bought 2 dyno max super turbo 3 in mufflers with dual exits put on the zr1 tips painted it black and it looks stk .super turbo mufflers 120 for both 150 for the zr1 exhaust and 130 to have a muffler guy put it together . there are videos of the car at the strip with this setup on it . sorry i dont know how to post them here but if you pm me your email i can send them to you from u tube. bill boudreau drove the car with this setup and he loves the sound ..its nice not to spend over 1000 dollars for a exhaust.its not stainless but it should last a good long time .

[sammy]

are your coils the stk ones that the car came with . i had 1 post go out on one of my coils and it acted just like your is doing now .

[EvanZR1]

They very well could be, I just searched the spreadsheet I made of all the receipts/maintenance I'd been given on it, and could find any mention of the coils ever being replaced. Guess it may be time to pull the plenum and do them. That would make sense as that's more kind of thing I'd associate the rough running/missing with. Guess the white smoke would be from unburnt fuel? I did notice a rich smell when this started as well.

[sammy]

also did you ck to see if you map sensor hose at the back of the plenum might have come off???? this will cause that to . also you can do the mat sensor relocation yourself .sure helps if you drag the car at the strip .before i moved it the sensor would read 170 deg while idling in the staging lanes . now it get max 5 deg hotter then the outside temp

[EvanZR1]

Not yet, will go check it now.

[sammy]

They very well could be, I just searched the spreadsheet I made of all the receipts/maintenance I'd been given on it, and could find any mention of the coils ever being replaced. Guess it may be time to pull the plenum and do them. That would make sense as that's more kind of thing I'd associate the rough running/missing with. Guess the white smoke would be from unburnt fuel? I did notice a rich smell when this started as well. give corey a call .believe me he will help in any way he can . he solved my problem over the phone many times . he is a true class guy

[sammy]

understand the frustration , dont know how well you know corey, he and i go way back and dont worry he will never leave you hanging. he is one of the most honest guys i have ever met. just wanted to share to put you at ease

[EvanZR1]

Oh, I'm sure Corey will be all over this as soon as he gets time. I know he's at BG, so I don't expect an immediate response from him. Checked the MAT sensor, and it's plugged in good. The thing that worries me the most is the oil, it's not just a little bit, there is a hand sized stain on the concrete under the car, so I'm very worried about that irregardless of what else is going on.

[sammy]

where is the stain located

[EvanZR1]

Directly under driver's side header collector (actually dripped on the header). Pretty much in line with rear of engine on driver's side.

[Kevin]

Directly under driver's side header collector (actually dripped on the header). Pretty much in line with rear of engine on driver's side.

sounds like a bolt may have backed out on the headers. your best bet is to call corey

[A26B]

Corey is indeed here in bowling green. He says that there are any number of things that could be causing your issues but first and foremost the O2 sensors could be a problem. Your injectors are freshly installed so more than likely they are ok but you could have an injector driver issue in the computer. Coils are original but they didn't show any signs of weakness on the dyno, but you can't rule them out completely. The oil leak is a concern for sure, probably the header stud on that side. He says he will call you first thing on Monday when he gets in the shop so you guys can make a game plan for getting her fixed up.

[EvanZR1]

Thanks Jerry. You have to love the ZR-1 community, such a good group of guys.

[A26B]

You know, they really are. And trust me when I say Corey probably won't sleep tonight worrying about your car!

[Locobob]

Hmmm oil getting onto headers is most likely the header stud, cam cover or possibly the cam position sensor. Ticking - likely an exhaust leak - quite possibly at the header gasket given the other symptoms. Smoke = burning oil. Rough running is likely a result of the exhaust leak throwing off the O2 sensor.

My best sight unseen guesses.

[Kevin]

Hmmm oil getting onto headers is most likely the header stud, cam cover or possibly the cam position sensor. Ticking - likely an exhaust leak - quite possibly at the header gasket given the other symptoms. Smoke = burning oil. Rough running is likely a result of the exhaust leak throwing off the O2 sensor.

My best sight unseen guesses.

it does sound like a header stud backed itself out

[EvanZR1]

Just thought I'd update this to let anyone that was interested know the answer. Turns out it was one of the "new" injectors stuck open. Swapped the originals back in, and it's running better. Will be sending the new ones back to Jon for him to check, they were rebuilt and apparently if they sit "dry" too long they can have issues.

[-=Jeff=-]

I had the same issue at first with one from Jon.. he will take care of you..

[Blue Flame Restorations]

Which Borla do you have?

To be honest, I'm not even sure. I think its the first system Borla ever had for ZR-1.

Here is a pic:

http://i159.photobucket.com/albums/t150/90koth/A4.jpg


Love the yellow!!!!!!!!!!

[ittlfly]

Love the yellow!!!!!!!!!!

Me too! :handshak:

[rhipsher]

Hmm! My 90 makes 357rwhp with just top end porting only. And I'm still running stock cats and manifolds with a Borla. 360rwhp seems pretty week with all the work you've had done. I would think you should be higher than that.

[sammy]

the lower than average figures are most likely due to corey not being ablr to put the timing in the car he would like to . nice thing about corey is he tunes the car safely so it will live. the borla is costing you at least 15 rwhp as i have tested just about all the cat back systems out there . if you removed the resonator and added a x pipe or balance tube you power woiuld get to where it should be .jmho

[EvanZR1]

Yeah, I was already thinking of replacing the Borla resonator with an x-pipe. I've been under it and looked at the inlets, and they are really restrictive. Once I get the new injectors back and finish up some exhaust work, I'll re-dyno. May even have Corey retune after that.

[4-cam]

I just removed my Borla resonator and replaced it with an x pipe. The car has less resonance inside than it did with the resonator in place. I was very surprised! Im glad the resonance is gone, but I wish it made a bit more noise. My Bro was following in his vette and he said it still sounded pretty mean from behind though.