[Z06] Less mild and more wild HCI build! (An American Heritage Performance tale)
07-07-2016, 12:55 AM
#1
Melting Slicks
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Less mild and more wild HCI build! (An American Heritage Performance tale)
If you do not want to read the entire write up then please feel free to jump down to the first bolded paragraph for the results. If you’re interested in the details and some of the thought that went into this build please enjoy the read.
Where do I begin? The last two years have been a journey of sorts. Without going into too much detail, as a frequent forum visitor I was aware of the potential issue inherent in many LS7 equipped cars. As my warranty expired I decided to be proactive and address the heads on my terms before the heads made the decision for me and rang up a higher bill.
I view the LS7 as one of the last great traditional Corvette drivetrain setups. Front/ mid engine, V8, large cubes and possibly one of the last normally aspirated engines available in a Corvette. As competitive as I see the sports car market these days and as big a piece of the equation as I see technology becoming I think it is only a matter of a few short years before Corvettes will only be had with forced induction, maybe fewer cylinders and even electric assist motors at the front to stay competitive on a global scene from a performance perspective. Just look at what Tesla is doing today as a pure electric, performance wise. Yes I recognize there are other limitations like range, appearance.
With all that said I have spent the past two years setting priorities for my solution and selecting the pieces I was going to use to do it. Normally I do my own work minus tuning but work these days consumes most of my time and if I took the car apart in my garage it would still be apart for longer than I am comfortable with so I went to plan “B”. Find a shop I can trust to do the mechanical work and tune. I am particular about my car and want someone that is willing to be just as meticulous as I can be. I found my solution about 1400 miles away in Southern California at American Heritage Performance! As I researched the heads and the options out there I came to realize that the operation Kohle has setup offers me the best one stop solution to get all the work done to my satisfaction in as economical a way as possible. It also gave me an excuse to road trip my car down there from Washington state and road trip it back.
I set three priorities on this project.
1. Fix the valve guide/ valve issue (Improve reliability over stock)
2. Sacrifice as little drivability in the process (My wife needs to be able to continue riding in the car)
3. Take advantage of the situation and add reasonable power in the process since the top of the motor will be apart (easier said than done especially keeping in mind priorities 1 and 2).
I’m sure in some people minds I went overboard with some aspects of my build and in other aspects I didn’t go far enough. While my choices may not be perfect they were the best I could make at the time I made them. Some of them simply presented themselves as an opportunity which was too good to pass up which is why I went the direction I did, case in point being my header selection which some will see as a mistake.
Here is the parts list/ what I had done.
1. AHP Stage 4 heads to include the Moldstar 90 guides, PSI 1511 springs and the Ferrea exhaust valves. I also had the heads milled .020 and asked Kohle to port and polish them.
2. Custom grind cam (very similar to TQ116) on EPS lobes. I worked on the this particular cam with Geoff at Energy Power Systems to deliver more power than the stock cam, take advantage of the better flowing heads and induction system and drive as near to stock as possible. The lobe design is also easier on the valve train unlike some other profiles out there. I also capped lift at .630 on both sides.
3. Pfadt 1 7/8” headers. Ceramic coated. I had a friend go FI (turbo) so these headers came off his car. Hard to pass up considering they were half price and almost new.
4. Ported factory throttle body. The NW102 can pose tuning and drivability issues based on my readings.
5. MSD Intake Manifold. Mamofied to include the stealth package.
6. Safe tune for 92 octane pump gas. There is a lot more to a tune than this but that was my one requirement going in.
Then came supporting mods I wasn’t planning on based on power output projections. My imagination started to take hold here and my ego made a break for it based on the above parts list.
1. Monster LT1-S twin disk clutch. Near factory feel and longevity with the clamping force to hold up to 700 RWHP. At this point I was unrealistically fantasizing about more power and felt I needed a beefier clutch. Still at some point I would have needed a clutch and this will likely be that last one I ever need to buy for this car…hopefully.
2. Siemens 63 lb fuel injectors. Factory units would be pushing the upper end of their duty cycle.
I dropped the car off in May and with plans to pick it up about 6 weeks later. As I added parts and the holidays approached we had to push the schedule out a couple more weeks. This was not easy as I found the longer the car was gone the more I missed it. Fast forward to July 5th and the car was completed by AHP and is ready for pick up. I plan to fly down this Friday the 8th to drive her back over the following two and a half days.
After reading all of this if you made it this far, I know all you want are the results and I need to shut up. Like a public speaker that can’t read his audience bear with me for a couple more sentences. Again my priorities focused on building a more reliable car. Not a much faster car although like I alluded to earlier as time passed and I missed my car more and more I fantasized and developed delusions of grandeur. My HP goal was to make C6 ZR1 numbers at the crank on an NA motor and I considered that somewhat of a stretch. Over time that number crept in my head up to 700. A completely unrealistic number that I had to keep telling myself was lie. When I got the email yesterday from Kohle that the car was finished I was hesitant to open it, afraid at what I would see and possibly resigned to the fact that I would spend the rest of the week bummed until I picked up my car that it didn’t live up to my pipe dream.
Well to say AHP and Kohle merely lived up to my expectations is a gross understatement. The numbers produced by the car far and away exceeded all my expectations. Even my pipe dream. RWHP is 606 and RWTQ is 558. Assuming about a 15% drivetrain loss that works out to around 710 HP and 655 TQ. All out of an NA 427 motor! These numbers reflect the car as I will take possession in a couple of days. It actually made more but was dialed back to a more conservative tune to protect against hurting the motor. Here is the dyno chart.
Unfortunately I did not get a baseline before the work was done so we don’t have a clear picture on what the actual gains are which is really what a chassis dyno is good for telling us but I did have the car tested right after break in when it was new and it did put down 465 RWHP and 425 RWTQ. That dyno chart is attached below. Not apples to apples but a decent approximation.
To quote Kohle “Pulls extremely hard (especially over 3500rpms). Has good street manners with only a mild/slight bit of low speed surging. Overall drives very nice and sounds very good.”
These are relative terms but I will be able to provide my account with respect to drivability when I start the drive home on Friday.
So far I couldn’t be happier with the results. I also had a wonderful experience minus the anxiety I put on myself waiting for the car to be finished. Between Kohle and his team plus the help from Geoff at EPS, Steve at Monster and the intake manifold that Tony built for me everything has come together beautifully. AHP brought all these pieces together in one place and built up a car that I expect to deliver me thrills for years to come. I can’t thank AHP enough for the level of service they have provided to this point. I started out simply wanting to protect my car for years to come and maybe pick up a little power along the way. While there are other more impressive builds out there, for what I was shooting for and what I got I never thought these kinds of results were achievable.
I also want to say thanks to those forum members I have PM'd with over the last couple of years and who have provided some great insight into modding the LS7.
For those interested in the condition of the valves here is the data from AHP. 2008 Z06 and the motor has about 28K and the car was stock except for a CAI installed around 12K. Oil was changed regularly often with Mobil 1 5W30 or Amsoil 5W30. Most of the miles are on the street but I have dragged it, done an HPDE and autocross. It also see’s redline on a regular basis. Intakes were in worse shape than the exhaust. Still all were on their way out.
Raw wiggle test results:
#1 int: .011"
#1 exh: .0085"
#3 int: .013"
#3 exh: .009"
#5 int: .010"
#5 exh: .0075"
#7 Int: .013"
#7 exh: .0095"
#2 int: .010"
#2 exh: .009"
#4 int: .0125"
#4 exh: .009"
#6 int: .012"
#6 exh: .0085"
#8 int: .011"
#8 exh: .009"
Mic'd and dialed #3 and #6 guides for comparison to the raw wiggle test.
clearance #3 int top of guide: .0059"
clearance #3 int middle of guide: .0056"
clearance #3 int bottom of guide: .0058"
clearance #3 exh top of guide: .0038"
clearance #3 exh middle of guide: .0035"
clearance #3 exh bottom of guide: .0039"
clearance #6 int top of guide: .0058"
clearance #6 int middle of guide: .0055"
clearance #6 int bottom of guide: .0056"
clearance #6 exh top of guide: .0038"
clearance #6 exh middle of guide: .0033"
clearance #6 exh bottom of guide: .0035"
Here are some more pictures.
My car is on the right.
Where do I begin? The last two years have been a journey of sorts. Without going into too much detail, as a frequent forum visitor I was aware of the potential issue inherent in many LS7 equipped cars. As my warranty expired I decided to be proactive and address the heads on my terms before the heads made the decision for me and rang up a higher bill.
I view the LS7 as one of the last great traditional Corvette drivetrain setups. Front/ mid engine, V8, large cubes and possibly one of the last normally aspirated engines available in a Corvette. As competitive as I see the sports car market these days and as big a piece of the equation as I see technology becoming I think it is only a matter of a few short years before Corvettes will only be had with forced induction, maybe fewer cylinders and even electric assist motors at the front to stay competitive on a global scene from a performance perspective. Just look at what Tesla is doing today as a pure electric, performance wise. Yes I recognize there are other limitations like range, appearance.
With all that said I have spent the past two years setting priorities for my solution and selecting the pieces I was going to use to do it. Normally I do my own work minus tuning but work these days consumes most of my time and if I took the car apart in my garage it would still be apart for longer than I am comfortable with so I went to plan “B”. Find a shop I can trust to do the mechanical work and tune. I am particular about my car and want someone that is willing to be just as meticulous as I can be. I found my solution about 1400 miles away in Southern California at American Heritage Performance! As I researched the heads and the options out there I came to realize that the operation Kohle has setup offers me the best one stop solution to get all the work done to my satisfaction in as economical a way as possible. It also gave me an excuse to road trip my car down there from Washington state and road trip it back.
I set three priorities on this project.
1. Fix the valve guide/ valve issue (Improve reliability over stock)
2. Sacrifice as little drivability in the process (My wife needs to be able to continue riding in the car)
3. Take advantage of the situation and add reasonable power in the process since the top of the motor will be apart (easier said than done especially keeping in mind priorities 1 and 2).
I’m sure in some people minds I went overboard with some aspects of my build and in other aspects I didn’t go far enough. While my choices may not be perfect they were the best I could make at the time I made them. Some of them simply presented themselves as an opportunity which was too good to pass up which is why I went the direction I did, case in point being my header selection which some will see as a mistake.
Here is the parts list/ what I had done.
1. AHP Stage 4 heads to include the Moldstar 90 guides, PSI 1511 springs and the Ferrea exhaust valves. I also had the heads milled .020 and asked Kohle to port and polish them.
2. Custom grind cam (very similar to TQ116) on EPS lobes. I worked on the this particular cam with Geoff at Energy Power Systems to deliver more power than the stock cam, take advantage of the better flowing heads and induction system and drive as near to stock as possible. The lobe design is also easier on the valve train unlike some other profiles out there. I also capped lift at .630 on both sides.
3. Pfadt 1 7/8” headers. Ceramic coated. I had a friend go FI (turbo) so these headers came off his car. Hard to pass up considering they were half price and almost new.
4. Ported factory throttle body. The NW102 can pose tuning and drivability issues based on my readings.
5. MSD Intake Manifold. Mamofied to include the stealth package.
6. Safe tune for 92 octane pump gas. There is a lot more to a tune than this but that was my one requirement going in.
Then came supporting mods I wasn’t planning on based on power output projections. My imagination started to take hold here and my ego made a break for it based on the above parts list.
1. Monster LT1-S twin disk clutch. Near factory feel and longevity with the clamping force to hold up to 700 RWHP. At this point I was unrealistically fantasizing about more power and felt I needed a beefier clutch. Still at some point I would have needed a clutch and this will likely be that last one I ever need to buy for this car…hopefully.
2. Siemens 63 lb fuel injectors. Factory units would be pushing the upper end of their duty cycle.
I dropped the car off in May and with plans to pick it up about 6 weeks later. As I added parts and the holidays approached we had to push the schedule out a couple more weeks. This was not easy as I found the longer the car was gone the more I missed it. Fast forward to July 5th and the car was completed by AHP and is ready for pick up. I plan to fly down this Friday the 8th to drive her back over the following two and a half days.
After reading all of this if you made it this far, I know all you want are the results and I need to shut up. Like a public speaker that can’t read his audience bear with me for a couple more sentences. Again my priorities focused on building a more reliable car. Not a much faster car although like I alluded to earlier as time passed and I missed my car more and more I fantasized and developed delusions of grandeur. My HP goal was to make C6 ZR1 numbers at the crank on an NA motor and I considered that somewhat of a stretch. Over time that number crept in my head up to 700. A completely unrealistic number that I had to keep telling myself was lie. When I got the email yesterday from Kohle that the car was finished I was hesitant to open it, afraid at what I would see and possibly resigned to the fact that I would spend the rest of the week bummed until I picked up my car that it didn’t live up to my pipe dream.
Well to say AHP and Kohle merely lived up to my expectations is a gross understatement. The numbers produced by the car far and away exceeded all my expectations. Even my pipe dream. RWHP is 606 and RWTQ is 558. Assuming about a 15% drivetrain loss that works out to around 710 HP and 655 TQ. All out of an NA 427 motor! These numbers reflect the car as I will take possession in a couple of days. It actually made more but was dialed back to a more conservative tune to protect against hurting the motor. Here is the dyno chart.
Unfortunately I did not get a baseline before the work was done so we don’t have a clear picture on what the actual gains are which is really what a chassis dyno is good for telling us but I did have the car tested right after break in when it was new and it did put down 465 RWHP and 425 RWTQ. That dyno chart is attached below. Not apples to apples but a decent approximation.
To quote Kohle “Pulls extremely hard (especially over 3500rpms). Has good street manners with only a mild/slight bit of low speed surging. Overall drives very nice and sounds very good.”
These are relative terms but I will be able to provide my account with respect to drivability when I start the drive home on Friday.
So far I couldn’t be happier with the results. I also had a wonderful experience minus the anxiety I put on myself waiting for the car to be finished. Between Kohle and his team plus the help from Geoff at EPS, Steve at Monster and the intake manifold that Tony built for me everything has come together beautifully. AHP brought all these pieces together in one place and built up a car that I expect to deliver me thrills for years to come. I can’t thank AHP enough for the level of service they have provided to this point. I started out simply wanting to protect my car for years to come and maybe pick up a little power along the way. While there are other more impressive builds out there, for what I was shooting for and what I got I never thought these kinds of results were achievable.
I also want to say thanks to those forum members I have PM'd with over the last couple of years and who have provided some great insight into modding the LS7.
For those interested in the condition of the valves here is the data from AHP. 2008 Z06 and the motor has about 28K and the car was stock except for a CAI installed around 12K. Oil was changed regularly often with Mobil 1 5W30 or Amsoil 5W30. Most of the miles are on the street but I have dragged it, done an HPDE and autocross. It also see’s redline on a regular basis. Intakes were in worse shape than the exhaust. Still all were on their way out.
Raw wiggle test results:
#1 int: .011"
#1 exh: .0085"
#3 int: .013"
#3 exh: .009"
#5 int: .010"
#5 exh: .0075"
#7 Int: .013"
#7 exh: .0095"
#2 int: .010"
#2 exh: .009"
#4 int: .0125"
#4 exh: .009"
#6 int: .012"
#6 exh: .0085"
#8 int: .011"
#8 exh: .009"
Mic'd and dialed #3 and #6 guides for comparison to the raw wiggle test.
clearance #3 int top of guide: .0059"
clearance #3 int middle of guide: .0056"
clearance #3 int bottom of guide: .0058"
clearance #3 exh top of guide: .0038"
clearance #3 exh middle of guide: .0035"
clearance #3 exh bottom of guide: .0039"
clearance #6 int top of guide: .0058"
clearance #6 int middle of guide: .0055"
clearance #6 int bottom of guide: .0056"
clearance #6 exh top of guide: .0038"
clearance #6 exh middle of guide: .0033"
clearance #6 exh bottom of guide: .0035"
Here are some more pictures.
My car is on the right.
Last edited by NW94Z; 07-07-2016 at 01:05 AM.
The following 3 users liked this post by NW94Z:
07-07-2016, 01:10 AM
#2
Race Director
I like the process you went thru to consider your upgrades. It is a similar process to what I did. At 46K miles 14 of my 16 valve guides were out of spec via full measurement.
I do wish more people would run before/after runs on the same dyno as stock LS7 dynojet numbers vary by 40+ HP. Your after numbers are very strong for a mid-level cam and ported OEM throttle body. Enjoy your build.
I do wish more people would run before/after runs on the same dyno as stock LS7 dynojet numbers vary by 40+ HP. Your after numbers are very strong for a mid-level cam and ported OEM throttle body. Enjoy your build.
07-07-2016, 08:55 AM
#3
Melting Slicks
Nice #'s but I wonder.................
How do your #'s compare to Dynojet SAE #'s? Are your #'s from the Dynapack SAE #'s also?
Can you post a larger image of your Dyanpack results?
How do your #'s compare to Dynojet SAE #'s? Are your #'s from the Dynapack SAE #'s also?
Can you post a larger image of your Dyanpack results?
07-07-2016, 09:15 AM
#4
Burning Brakes
Interesting.
What are the cam specs if you could share. Will like to see how those numbers compare to a DJ.
What are the cam specs if you could share. Will like to see how those numbers compare to a DJ.
07-07-2016, 10:03 AM
#5
If you do not want to read the entire write up then please feel free to jump down to the first bolded paragraph for the results. If you’re interested in the details and some of the thought that went into this build please enjoy the read.
Where do I begin? The last two years have been a journey of sorts. Without going into too much detail, as a frequent forum visitor I was aware of the potential issue inherent in many LS7 equipped cars. As my warranty expired I decided to be proactive and address the heads on my terms before the heads made the decision for me and rang up a higher bill.
I view the LS7 as one of the last great traditional Corvette drivetrain setups. Front/ mid engine, V8, large cubes and possibly one of the last normally aspirated engines available in a Corvette. As competitive as I see the sports car market these days and as big a piece of the equation as I see technology becoming I think it is only a matter of a few short years before Corvettes will only be had with forced induction, maybe fewer cylinders and even electric assist motors at the front to stay competitive on a global scene from a performance perspective. Just look at what Tesla is doing today as a pure electric, performance wise. Yes I recognize there are other limitations like range, appearance.
With all that said I have spent the past two years setting priorities for my solution and selecting the pieces I was going to use to do it. Normally I do my own work minus tuning but work these days consumes most of my time and if I took the car apart in my garage it would still be apart for longer than I am comfortable with so I went to plan “B”. Find a shop I can trust to do the mechanical work and tune. I am particular about my car and want someone that is willing to be just as meticulous as I can be. I found my solution about 1400 miles away in Southern California at American Heritage Performance! As I researched the heads and the options out there I came to realize that the operation Kohle has setup offers me the best one stop solution to get all the work done to my satisfaction in as economical a way as possible. It also gave me an excuse to road trip my car down there from Washington state and road trip it back.
I set three priorities on this project.
1. Fix the valve guide/ valve issue (Improve reliability over stock)
2. Sacrifice as little drivability in the process (My wife needs to be able to continue riding in the car)
3. Take advantage of the situation and add reasonable power in the process since the top of the motor will be apart (easier said than done especially keeping in mind priorities 1 and 2).
I’m sure in some people minds I went overboard with some aspects of my build and in other aspects I didn’t go far enough. While my choices may not be perfect they were the best I could make at the time I made them. Some of them simply presented themselves as an opportunity which was too good to pass up which is why I went the direction I did, case in point being my header selection which some will see as a mistake.
Here is the parts list/ what I had done.
1. AHP Stage 4 heads to include the Moldstar 90 guides, PSI 1511 springs and the Ferrea exhaust valves. I also had the heads milled .020 and asked Kohle to port and polish them.
2. Custom grind cam (very similar to TQ116) on EPS lobes. I worked on the this particular cam with Geoff at Energy Power Systems to deliver more power than the stock cam, take advantage of the better flowing heads and induction system and drive as near to stock as possible. The lobe design is also easier on the valve train unlike some other profiles out there. I also capped lift at .630 on both sides.
3. Pfadt 1 7/8” headers. Ceramic coated. I had a friend go FI (turbo) so these headers came off his car. Hard to pass up considering they were half price and almost new.
4. Ported factory throttle body. The NW102 can pose tuning and drivability issues based on my readings.
5. MSD Intake Manifold. Mamofied to include the stealth package.
6. Safe tune for 92 octane pump gas. There is a lot more to a tune than this but that was my one requirement going in.
Then came supporting mods I wasn’t planning on based on power output projections. My imagination started to take hold here and my ego made a break for it based on the above parts list.
1. Monster LT1-S twin disk clutch. Near factory feel and longevity with the clamping force to hold up to 700 RWHP. At this point I was unrealistically fantasizing about more power and felt I needed a beefier clutch. Still at some point I would have needed a clutch and this will likely be that last one I ever need to buy for this car…hopefully.
2. Siemens 63 lb fuel injectors. Factory units would be pushing the upper end of their duty cycle.
I dropped the car off in May and with plans to pick it up about 6 weeks later. As I added parts and the holidays approached we had to push the schedule out a couple more weeks. This was not easy as I found the longer the car was gone the more I missed it. Fast forward to July 5th and the car was completed by AHP and is ready for pick up. I plan to fly down this Friday the 8th to drive her back over the following two and a half days.
After reading all of this if you made it this far, I know all you want are the results and I need to shut up. Like a public speaker that can’t read his audience bear with me for a couple more sentences. Again my priorities focused on building a more reliable car. Not a much faster car although like I alluded to earlier as time passed and I missed my car more and more I fantasized and developed delusions of grandeur. My HP goal was to make C6 ZR1 numbers at the crank on an NA motor and I considered that somewhat of a stretch. Over time that number crept in my head up to 700. A completely unrealistic number that I had to keep telling myself was lie. When I got the email yesterday from Kohle that the car was finished I was hesitant to open it, afraid at what I would see and possibly resigned to the fact that I would spend the rest of the week bummed until I picked up my car that it didn’t live up to my pipe dream.
Well to say AHP and Kohle merely lived up to my expectations is a gross understatement. The numbers produced by the car far and away exceeded all my expectations. Even my pipe dream. RWHP is 606 and RWTQ is 558. Assuming about a 15% drivetrain loss that works out to around 710 HP and 655 TQ. All out of an NA 427 motor! These numbers reflect the car as I will take possession in a couple of days. It actually made more but was dialed back to a more conservative tune to protect against hurting the motor. Here is the dyno chart.
Attachment 47998257
Unfortunately I did not get a baseline before the work was done so we don’t have a clear picture on what the actual gains are which is really what a chassis dyno is good for telling us but I did have the car tested right after break in when it was new and it did put down 465 RWHP and 425 RWTQ. That dyno chart is attached below. Not apples to apples but a decent approximation.
Attachment 47998258
To quote Kohle “Pulls extremely hard (especially over 3500rpms). Has good street manners with only a mild/slight bit of low speed surging. Overall drives very nice and sounds very good.”
These are relative terms but I will be able to provide my account with respect to drivability when I start the drive home on Friday.
So far I couldn’t be happier with the results. I also had a wonderful experience minus the anxiety I put on myself waiting for the car to be finished. Between Kohle and his team plus the help from Geoff at EPS, Steve at Monster and the intake manifold that Tony built for me everything has come together beautifully. AHP brought all these pieces together in one place and built up a car that I expect to deliver me thrills for years to come. I can’t thank AHP enough for the level of service they have provided to this point. I started out simply wanting to protect my car for years to come and maybe pick up a little power along the way. While there are other more impressive builds out there, for what I was shooting for and what I got I never thought these kinds of results were achievable.
I also want to say thanks to those forum members I have PM'd with over the last couple of years and who have provided some great insight into modding the LS7.
For those interested in the condition of the valves here is the data from AHP. 2008 Z06 and the motor has about 28K and the car was stock except for a CAI installed around 12K. Oil was changed regularly often with Mobil 1 5W30 or Amsoil 5W30. Most of the miles are on the street but I have dragged it, done an HPDE and autocross. It also see’s redline on a regular basis. Intakes were in worse shape than the exhaust. Still all were on their way out.
Raw wiggle test results:
#1 int: .011"
#1 exh: .0085"
#3 int: .013"
#3 exh: .009"
#5 int: .010"
#5 exh: .0075"
#7 Int: .013"
#7 exh: .0095"
#2 int: .010"
#2 exh: .009"
#4 int: .0125"
#4 exh: .009"
#6 int: .012"
#6 exh: .0085"
#8 int: .011"
#8 exh: .009"
Mic'd and dialed #3 and #6 guides for comparison to the raw wiggle test.
clearance #3 int top of guide: .0059"
clearance #3 int middle of guide: .0056"
clearance #3 int bottom of guide: .0058"
clearance #3 exh top of guide: .0038"
clearance #3 exh middle of guide: .0035"
clearance #3 exh bottom of guide: .0039"
clearance #6 int top of guide: .0058"
clearance #6 int middle of guide: .0055"
clearance #6 int bottom of guide: .0056"
clearance #6 exh top of guide: .0038"
clearance #6 exh middle of guide: .0033"
clearance #6 exh bottom of guide: .0035"
Here are some more pictures.
My car is on the right.
Attachment 47998259
Attachment 47998260
Attachment 47998261
Attachment 47998262
Where do I begin? The last two years have been a journey of sorts. Without going into too much detail, as a frequent forum visitor I was aware of the potential issue inherent in many LS7 equipped cars. As my warranty expired I decided to be proactive and address the heads on my terms before the heads made the decision for me and rang up a higher bill.
I view the LS7 as one of the last great traditional Corvette drivetrain setups. Front/ mid engine, V8, large cubes and possibly one of the last normally aspirated engines available in a Corvette. As competitive as I see the sports car market these days and as big a piece of the equation as I see technology becoming I think it is only a matter of a few short years before Corvettes will only be had with forced induction, maybe fewer cylinders and even electric assist motors at the front to stay competitive on a global scene from a performance perspective. Just look at what Tesla is doing today as a pure electric, performance wise. Yes I recognize there are other limitations like range, appearance.
With all that said I have spent the past two years setting priorities for my solution and selecting the pieces I was going to use to do it. Normally I do my own work minus tuning but work these days consumes most of my time and if I took the car apart in my garage it would still be apart for longer than I am comfortable with so I went to plan “B”. Find a shop I can trust to do the mechanical work and tune. I am particular about my car and want someone that is willing to be just as meticulous as I can be. I found my solution about 1400 miles away in Southern California at American Heritage Performance! As I researched the heads and the options out there I came to realize that the operation Kohle has setup offers me the best one stop solution to get all the work done to my satisfaction in as economical a way as possible. It also gave me an excuse to road trip my car down there from Washington state and road trip it back.
I set three priorities on this project.
1. Fix the valve guide/ valve issue (Improve reliability over stock)
2. Sacrifice as little drivability in the process (My wife needs to be able to continue riding in the car)
3. Take advantage of the situation and add reasonable power in the process since the top of the motor will be apart (easier said than done especially keeping in mind priorities 1 and 2).
I’m sure in some people minds I went overboard with some aspects of my build and in other aspects I didn’t go far enough. While my choices may not be perfect they were the best I could make at the time I made them. Some of them simply presented themselves as an opportunity which was too good to pass up which is why I went the direction I did, case in point being my header selection which some will see as a mistake.
Here is the parts list/ what I had done.
1. AHP Stage 4 heads to include the Moldstar 90 guides, PSI 1511 springs and the Ferrea exhaust valves. I also had the heads milled .020 and asked Kohle to port and polish them.
2. Custom grind cam (very similar to TQ116) on EPS lobes. I worked on the this particular cam with Geoff at Energy Power Systems to deliver more power than the stock cam, take advantage of the better flowing heads and induction system and drive as near to stock as possible. The lobe design is also easier on the valve train unlike some other profiles out there. I also capped lift at .630 on both sides.
3. Pfadt 1 7/8” headers. Ceramic coated. I had a friend go FI (turbo) so these headers came off his car. Hard to pass up considering they were half price and almost new.
4. Ported factory throttle body. The NW102 can pose tuning and drivability issues based on my readings.
5. MSD Intake Manifold. Mamofied to include the stealth package.
6. Safe tune for 92 octane pump gas. There is a lot more to a tune than this but that was my one requirement going in.
Then came supporting mods I wasn’t planning on based on power output projections. My imagination started to take hold here and my ego made a break for it based on the above parts list.
1. Monster LT1-S twin disk clutch. Near factory feel and longevity with the clamping force to hold up to 700 RWHP. At this point I was unrealistically fantasizing about more power and felt I needed a beefier clutch. Still at some point I would have needed a clutch and this will likely be that last one I ever need to buy for this car…hopefully.
2. Siemens 63 lb fuel injectors. Factory units would be pushing the upper end of their duty cycle.
I dropped the car off in May and with plans to pick it up about 6 weeks later. As I added parts and the holidays approached we had to push the schedule out a couple more weeks. This was not easy as I found the longer the car was gone the more I missed it. Fast forward to July 5th and the car was completed by AHP and is ready for pick up. I plan to fly down this Friday the 8th to drive her back over the following two and a half days.
After reading all of this if you made it this far, I know all you want are the results and I need to shut up. Like a public speaker that can’t read his audience bear with me for a couple more sentences. Again my priorities focused on building a more reliable car. Not a much faster car although like I alluded to earlier as time passed and I missed my car more and more I fantasized and developed delusions of grandeur. My HP goal was to make C6 ZR1 numbers at the crank on an NA motor and I considered that somewhat of a stretch. Over time that number crept in my head up to 700. A completely unrealistic number that I had to keep telling myself was lie. When I got the email yesterday from Kohle that the car was finished I was hesitant to open it, afraid at what I would see and possibly resigned to the fact that I would spend the rest of the week bummed until I picked up my car that it didn’t live up to my pipe dream.
Well to say AHP and Kohle merely lived up to my expectations is a gross understatement. The numbers produced by the car far and away exceeded all my expectations. Even my pipe dream. RWHP is 606 and RWTQ is 558. Assuming about a 15% drivetrain loss that works out to around 710 HP and 655 TQ. All out of an NA 427 motor! These numbers reflect the car as I will take possession in a couple of days. It actually made more but was dialed back to a more conservative tune to protect against hurting the motor. Here is the dyno chart.
Attachment 47998257
Unfortunately I did not get a baseline before the work was done so we don’t have a clear picture on what the actual gains are which is really what a chassis dyno is good for telling us but I did have the car tested right after break in when it was new and it did put down 465 RWHP and 425 RWTQ. That dyno chart is attached below. Not apples to apples but a decent approximation.
Attachment 47998258
To quote Kohle “Pulls extremely hard (especially over 3500rpms). Has good street manners with only a mild/slight bit of low speed surging. Overall drives very nice and sounds very good.”
These are relative terms but I will be able to provide my account with respect to drivability when I start the drive home on Friday.
So far I couldn’t be happier with the results. I also had a wonderful experience minus the anxiety I put on myself waiting for the car to be finished. Between Kohle and his team plus the help from Geoff at EPS, Steve at Monster and the intake manifold that Tony built for me everything has come together beautifully. AHP brought all these pieces together in one place and built up a car that I expect to deliver me thrills for years to come. I can’t thank AHP enough for the level of service they have provided to this point. I started out simply wanting to protect my car for years to come and maybe pick up a little power along the way. While there are other more impressive builds out there, for what I was shooting for and what I got I never thought these kinds of results were achievable.
I also want to say thanks to those forum members I have PM'd with over the last couple of years and who have provided some great insight into modding the LS7.
For those interested in the condition of the valves here is the data from AHP. 2008 Z06 and the motor has about 28K and the car was stock except for a CAI installed around 12K. Oil was changed regularly often with Mobil 1 5W30 or Amsoil 5W30. Most of the miles are on the street but I have dragged it, done an HPDE and autocross. It also see’s redline on a regular basis. Intakes were in worse shape than the exhaust. Still all were on their way out.
Raw wiggle test results:
#1 int: .011"
#1 exh: .0085"
#3 int: .013"
#3 exh: .009"
#5 int: .010"
#5 exh: .0075"
#7 Int: .013"
#7 exh: .0095"
#2 int: .010"
#2 exh: .009"
#4 int: .0125"
#4 exh: .009"
#6 int: .012"
#6 exh: .0085"
#8 int: .011"
#8 exh: .009"
Mic'd and dialed #3 and #6 guides for comparison to the raw wiggle test.
clearance #3 int top of guide: .0059"
clearance #3 int middle of guide: .0056"
clearance #3 int bottom of guide: .0058"
clearance #3 exh top of guide: .0038"
clearance #3 exh middle of guide: .0035"
clearance #3 exh bottom of guide: .0039"
clearance #6 int top of guide: .0058"
clearance #6 int middle of guide: .0055"
clearance #6 int bottom of guide: .0056"
clearance #6 exh top of guide: .0038"
clearance #6 exh middle of guide: .0033"
clearance #6 exh bottom of guide: .0035"
Here are some more pictures.
My car is on the right.
Attachment 47998259
Attachment 47998260
Attachment 47998261
Attachment 47998262
07-07-2016, 10:17 AM
#6
Safety Car
Well thought out combination and goals. Enjoy your new power
07-07-2016, 11:14 AM
#7
Melting Slicks
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I like the process you went thru to consider your upgrades. It is a similar process to what I did. At 46K miles 14 of my 16 valve guides were out of spec via full measurement.
I do wish more people would run before/after runs on the same dyno as stock LS7 dynojet numbers vary by 40+ HP. Your after numbers are very strong for a mid-level cam and ported OEM throttle body. Enjoy your build.
I do wish more people would run before/after runs on the same dyno as stock LS7 dynojet numbers vary by 40+ HP. Your after numbers are very strong for a mid-level cam and ported OEM throttle body. Enjoy your build.
At the end of the day I have a rebuilt top end that should give me trouble free driving for many years and the car has a little more performance to go with it all.
07-07-2016, 11:20 AM
#8
Melting Slicks
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This is a great question and I don't know that there really is a good answer or at least an accurate answer. The Dynapack set up bolts directly to the cars hubs as opposed to sitting on a set of rollers with the tires and from what i have read is a more consistent tool for tuning and results but again how those results compare is a largely unknown variable. I think it's really about tuning and less about actual hard performance numbers. We can compare to some degree but that may only create more debate.
07-07-2016, 11:25 AM
#10
Melting Slicks
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Yes and no. The injectors do drop straight in but they will not connect to the Z06 wiring harness. I bought these through Lingenfelter for the Z06 application and they made no mention of a connector compatibility issue. Kohle did have to add an adapter that fits between the injector and terminal in order for them to work. As for tuning I would have to defer that question to Kohle.
07-07-2016, 12:55 PM
#12
Curious what your overall cost was on this if you are comfortable sharing. Feel free to PM me if you don't want to post it here. I recently purchased an 08' with 73k and I don't believe the heads have ever been done and would like to do something similar.
07-07-2016, 01:07 PM
#13
Melting Slicks
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I did have a budget and ended up exceeding it. Largely due to two things. I added the MSD intake which I had not planned on but when I saw what Tony was doing with them I liked the potential power gains without giving up anything on my first two priorities and I like the factory look. The other items I hadn't considered were the supporting mods like the injectors and clutch. If you want some specifics as far as cost go PM me and I will share with you. I still came in considerably less than what it would have cost if the motor had let go out of warranty.
Last edited by NW94Z; 07-07-2016 at 01:09 PM.
07-07-2016, 02:05 PM
#14
Team Owner
07-07-2016, 03:51 PM
#16
07-07-2016, 04:13 PM
#17
Team Owner
Not a fan of pfadt headers but since you got them used I guess that is OK. That is what I was going to say. Looking back though I would add a nw102. Tuning issues was when they first came out and used a c5 motor. Any nw102 made in last 3-4 years are nothing more than 1-2 minor tune tweaks. If your tuner can't handle them then they shouldn't be touching your car. You would probably see a solid 10hp/10tq from a nw102 and the three cars I've done with them all drove better and had better throttle response and less cam issues.
Dynapak can read high or low depending on setup. For example your chart shows 3.43 gear which is wrong and will skew numbers.
Dynapak can read high or low depending on setup. For example your chart shows 3.43 gear which is wrong and will skew numbers.
Last edited by Unreal; 07-07-2016 at 04:14 PM.
07-07-2016, 04:26 PM
#18
Team Owner
Excellent built, and excellent results...but no surprise there, Kohle and his team at AHP are top notch. 
Most importantly, thank you for including a bore mic comparison to the wiggle results; which further bolsters what most have learned over time. Is the wiggle test precise? No; but if its performed correctly, it certainly can give a very good indication that something isn't right.
Most importantly, thank you for including a bore mic comparison to the wiggle results; which further bolsters what most have learned over time. Is the wiggle test precise? No; but if its performed correctly, it certainly can give a very good indication that something isn't right.
07-07-2016, 05:23 PM
#20
Looking back though I would add a nw102. Tuning issues was when they first came out and used a c5 motor. Any nw102 made in last 3-4 years are nothing more than 1-2 minor tune tweaks. If your tuner can't handle them then they shouldn't be touching your car. You would probably see a solid 10hp/10tq from a nw102 and the three cars I've done with them all drove better and had better throttle response and less cam issues