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#1 |
![]() Join Date: Jun 2006
Location: Sparks, NV
Posts: 2,852
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After doing all the usual upgrades on my engine, Ported top end, chip, SW headers, modified corsa, new injectors, HO coils etc. I had the car dyno'd a couple weeks ago and was somewhat disappointed the get HP/Torque readings of 369/370. While the torque reading is good, the HP output is about 20 lower than expected. While there are alot of variables I suspected I knew what the problem was.
After all the mods were done I felt the Corsa system was too loud for my taste. I had a local exhaust shop swap out the corsa resonator for an X-pipe and a magnaflow resonator. I loved the sound and was happy till the dyno run. I finally jacked the car up and crawled under to take a look at their work today. What I didn't realize is that for some reason the shop used 2" pipe between the x-pipe and the resonator and between the resonator and the connection to the 2.5" Muffler pipes. This meant I had a system with a 3" header collector into 3" HF Cats into a 2.5" x-pipe into 2" pipe into a 2.5" resonator into 2" pipe into 2.5" mufflers. Not condusive to good flow. It just goes to show you if you want things done right you have to do them yourself and inspect the work others do for you before you accept it. The resonator and 2" pipes will have to come out. Since the corsa system is a 2.5" system I will leave the 2.5" x-pipe. I'm thinking of using a Borla resonator. The Corsa resonator is nothing more than straight pipe with an expansion chamber. It looks like the Magnaflow resonator that was used has pipe spacing that is too far apart. I need a resonator with a bit more muffling ability than the Corsa and that aligns correctly with the pipes. Given that I want it quieter I will have to give up some HP. But 20 is more than I am willing to give. Other than the Borla resonator any thoughts on what to use in there? H ![]()
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90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold. Last edited by Ccmano; 07-11-2009 at 06:34 PM. |
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#2 |
![]() Join Date: Mar 2007
Location: Crystal Lake, IL
Posts: 7,194
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You should through the exhaust from my 92 on it while its off the car and head to the dyno
![]() I would call Mike at twisted....he used 3' stainless on my car and I am sure he would change it....is the 2" what the kit came with?
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LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
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#3 |
![]() Join Date: Mar 2007
Location: Crystal Lake, IL
Posts: 7,194
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![]() ![]() Only bad thing about the Borla is its 2.25 neck down as it enters the resonator
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LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
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#4 |
Join Date: Aug 2008
Location: Houston 90 Red ZR-1
Posts: 2,320
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I'm doing all of the same mods you did right now. I don't want to set myself up for dissapointment by having expectations of big dyno #'s. I've got a Borla exhaust system right now and like the sound of it. It may not be the best exhuast performance wise but after top end porting and Jeal headers and tuning we will see. I have no idea what to expect from it all. I just hope it puts a smile on my face.
Last edited by rhipsher; 07-11-2009 at 07:42 PM. |
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#5 | |
![]() ![]() Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,493
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As for noise, I have a Borla resonator, if you want to try it. I just finished hanging my 3" system under my Z today. It still needs some regulating to get it all aligned right. Soon as I can arrange it, I'm also going to add the "Power Stick" 18" mufflers in place of a resonator (behind the SW crossover), and then going thru the Maganaflow twin tube mufflers. It will be a true 3" all the way to the muffler inlet that does shrink down to 2.5. But, I don't think a restriction that far back is going to result in much loss. Certainly it is better than the obstruction in the B&B mufflers. I don't mind a little noise, but don't want to have to shout to carry on a conversation while in cruise mode. I'll let y'all know how it works out. P.
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Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry |
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#6 | |
![]() Join Date: Jul 2007
Location: Bartlett, IL
Posts: 7,154
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I would say buy the X pipe resonator form Paul.. it is the magnaflow set up.. that would be better
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1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978 |
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#7 |
![]() Join Date: May 2008
Location: USA
Posts: 1,096
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You should be at 450 or 400 RWHP with your setup.
The exhaust is hurting some but not that bad. I have borla on my car and I'm probably leaving 10HP on the table over a B&B system. Mine sounds alittle throaty but more like a sleeper - I prefer that over a bunch of resonance. |
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#8 |
![]() Join Date: Dec 2004
Location: Jacksonville, FL USA
Posts: 4,645
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Hans, is the top end P & P including head porting and re-degreeing of the cams?
I'm asking as your dyno numbers are exactly like a 90 that I inquired about. He had a P&P to the plenum and I/H's and a chip and headers w/o cats. The P&P and chip was mail order from Mr. Haibeck's shop and the owner did his own assembly work. His heads & cams were not touched, and his dyno sheets which he posted in his add were right at a 365 hp avg for three runs. I don't remember the brand of headers and the exhaust.... ![]() ![]() Tom
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1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member |
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#9 | |
![]() ![]() Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,493
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Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry |
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#10 |
![]() Join Date: Dec 2004
Location: Jacksonville, FL USA
Posts: 4,645
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Yea, Paul. The other thing that I don't recall for sure was the brand of dyno....I think it was Dyno-Jet?
But it's what this 90's numbers were. This was when I was looking for a Z to buy, I was a noob so I knew very little about any of the finer points on our cars. This guy was generous in that he took the time to give me some heads up on what I should be buying in a used Z. ![]() Tom
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1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member |
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