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To date, I've kept the exhaust system aft of the converters stock. Eventually, I'm going to have CF member "Josh B" modify my production '12/'13 mufflers for increased flow.
I'm curious now; what kind of modification is this?
I'm curious now; what kind of modification is this?
OE axle back exhaust necks down to ~2.5" just before entering the mufflers (and the rest of the way back from there). Josh opens it up to a full 3 inches...
OE axle back exhaust necks down to ~2.5" just before entering the mufflers (and the rest of the way back from there). Josh opens it up to a full 3 inches...
Hey Hib, can you write up a review of the car and post it up here on the forum?
When I decided I "needed" a streetable, 600-hp LS7, key reasons why I went to Katech were: a rich history of building successful road racing and circle track engines and its commitment to Chevrolet and the Corvette. As for the LS7 in particular, at the time I took my car to Katech for the Street Attack treatment, the company had built just under 100 performance-enhanced C6 ZO6es for street, street/track and track only and there had been an even greater number of LS7 crate engines which had gone at the door at Katech.
Fritz Kayl is the "Ka" in "Katech" and is who, along with Warren Frieze, founded the company over 40 years ago. I fondly remember what he told me over a dozen years ago, for an article I wrote for the now-defunct Corvette Quarterly magazine. "I became a Chevy guy in my teens," Kayl said, "and I never wavered–a lot of loyalty there. I'm very proud of that. In the race engine business, it's not so much getting things right; it's how many things you do wrong which makes you a winner or a looser. At Katech, we try not to 'out-trick' ourselves. We focus attention on science and engineering theory and practice rather than trying to find the latest 'hot trick'. Our aim is to take a conservative approach which pays off in reliablity and durability. We do everything in our power to win races. To work with Corvette," Fritz continued, "to go to Le Mans and win five out of the last six tries with an American race car is a dream come true. I get very emotional about it. I'm proud of the accomplishments of this company."
Has this approach worked? Look at the record. Katech-built Chevrolet engines have won hundreds of races and while that that resulted in championships in the American Le Mans Series (six-times); SCCA Trans-Am (five-times); ASA (four-times); NASCAR Xfinity series (three-times) and IMSA GTS (twice), Katech's greatest success has been in endurance road racing at the international level. Katech engines powered Corvette C5.Rs and C6.Rs to wins at the 24 Hours of Le Mans (six-times), Daytona 24 (twice), 24 Hours of Spa (twice), 24 Hours of Zolder: (twice), 12 Hours of Sebring: (six times) and the Road Atlanta Petit Le Mans 10-hrs (seven-times). If that list of accomplishments doesn't explain Katech's expertise at building GM Gen 4 V8s that make a lot of power and do it reliably for a long time, then maybe you don't understand English very well.
That said, even Fritz Kayl would agree that it's impossible to be perfect all the time. There's always that 1/2 of one percent of the time where "Murphy's Law" comes into play. That was the case with my Street Attack build. In spite of everyone's best intentions, the engine has problems. Initially, there was some hesitation on Katech's part to work with me solving those problems, but after Katech President, Steve Spurr and I had a email exchange which "cleared the air", we've agreed that I will ship my car back to Katech in Michigan and they will remedy the engine's troubles.
There were four issues that prevented my Street Attack build from living up to Katech's reputation for reliable, durable, performance-enhanced LS7s.
1) For an engine with the Torquer 116 camshaft, idle quality and light-load drivability did not meet my expectations.
2) Anytime the engine was run over 6000 rpm, the A/C compressor drive belt would jump two grooves rearward on the crankshaft damper. If not repositioned before further high rpm operation, the belt would shread.
3) In five months and 4989 miles, the engine has used 11 quarts of oil. Right after Katech did the work, oil use was 2000 miles per quart, but by early February, it had deteriorated to about 200 miles per quart. The engine has only been driven on the street and never tracked.
4) In road testing, during wide-open-throttle acceleration runs, in third gear from 1500-rpm to 6800-rpm, the engine suffers significant detonation resulting in a great deal of knock retard.
Calibration work fixed issue #1. At this point, idle quality and light-load drivability is improved. I am thankful for HPTuners. Without that software, I'd have been up S**t Creek without a paddle.
With #2, initially, because I never had the problem previous to Katech's work, I thought it was caused by the ATI crankshaft vibration damper Katech installed. I contacted Jason looking for a solution. He got in touch with ATI and they told him the problem was the A/C belt tensioner. I replaced the OE tensioner with an aftermarket unit from Continental, but to no avail. The the A/C belt kept jumping grooves. I bought a second tensioner, this one a Dayco. That didn't solve the problem, either. At that point, I decided it was unlikely this was a problem with belt tensioners.
The solution came from a likely source, this forum site after I posted a question about ATI dampers. Subsequently, CF Senior Member "double06" and I had a PM discussion about his experiences with the ATI Super Damper for LS7s. The original ATI design had no shoulder behind the A/C drive belt grooves. Apparently, this was the cause of a widespread A/C "belt throwing" problem which had ATI changing the design by adding a shoulder about .100-in high. The stock damper's shoulder is .160-in high. The belt I was using, a Continental Elite (which is the Goodyear Gatorback design which Conti now owns) had failed, so I reinstalled the stock belt which, I had kept as a spare. The stock belt stayed in place during repeated high rpm tests.
That got me thinking about slight differences in belt lengths. It was difficult to find effective length information about some of the belts on the market, but of belts for which I obtained data, the Continental Elite was the longest. I physically compared it to the OE belt, which is branded "Mitsubishi" and found it visibly shorter. Using listings on rockauto.com, I found the belt with the shortest effective length of belt makers which published lengths was a Dayco, so I ordered one. It didn't fit. There was no way, working by myself under the car, that I could get the Dayco on, so I went back to the OE belt. I'll save the Dayco to when I have someone to help me install it–one person underneath holding the tensioner back and another person working from the top to pry the belt over the A/C compressor pulley.
Bottom line: the problem was the "second design" ATI Damper and its sensitivity to belt length.
Ok, now the biggie, #3: oil use. The engine is not leaking it. The engine is burning it and under high load it burns a lot of it. I've had the throttle body off to find the inside of the intake manifold covered with oil film and pools of oil in "low spots" in the manifold's interior. This week, I borescoped #3 cylinder and could see what looked like oil residue on the piston top. At high rpm, the engine sometimes emits visible smoke. My guess is the oil is getting into the intake because of an as-yet unidentified crankcase breathing or windage problem. Some have said: install a "catch can" but that's not a solution. I'd be constantly emptying it. Some service action needs to be taken to get oil use back to 2000 miles per quart or better.
Lastly, #4: knock retard. The engine detonates quite a bit at wide open throttle from mid-range rpm on up. I reduced spark advance in the high octane table to only 12° BTDC in some areas and the engine was still getting modest KR. My guess is the detonation is being caused by oil ingestion and that's not going to change until #3 is fixed.
Well...that's the scoop on my Street Attack ZO6. I've stopped driving the car and am looking forward to getting the car loaded on a Pilot Transportation truck and on its way back to Katech. I'm grateful to Katech President, Steve Spurr; Director of Engineering Operations, Chris Meszaros and Director of Aftermarket Operations, Jason Harding, for their help with this difficult situation.
With all that oil consumption, it sounds like piston oil rings could be the issue or piston lands to tight. I had a SBC engine with custom Weisco pistons and oil consumption was terrible as you describe.
Turned out, I sent pistons back to Weisco and the land clearances were slightly too tight, not allowing the oil ring to seal against the cylinder properly. Weisco sent me new ones and issue was resolved. Still have that engine in my 69 Camaro.
With all that oil consumption, it sounds like piston oil rings could be the issue or piston lands to tight. I had a SBC engine with custom Weisco pistons and oil consumption was terrible as you describe.
Turned out, I sent pistons back to Weisco and the land clearances were slightly too tight, not allowing the oil ring to seal against the cylinder properly. Weisco sent me new ones and issue was resolved. Still have that engine in my 69 Camaro.
The problem has most of us, including the guys at Katech, scratching our heads.
No question that something "went away" in that motor as, initially, oil use (2000-mi. per quart), while a bit high for my taste, was acceptable by many standards, including the one GM uses for warranty work. Over the period of several months it went from 2000- to 200-mi per quart. I would have thought, if i had the same problem as you had with oil ring clearance, I'd would have had high oil use from the get-go.
In any event, the car leaves here today on a Pilot Transport truck headed for Katech. I've grown tired of speculating what the problem might be and am eagerly awaiting Katech's report once they have the engine apart.
Last edited by Hib Halverson; 05-12-2018 at 12:21 PM.
There were four issues that prevented my Street Attack build from living up to Katech's reputation for reliable, durable, performance-enhanced LS7s.
1) For an engine with the Torquer 116 camshaft, idle quality and light-load drivability did not meet my expectations.
2) Anytime the engine was run over 6000 rpm, the A/C compressor drive belt would jump two grooves rearward on the crankshaft damper. If not repositioned before further high rpm operation, the belt would shread.
3) In five months and 4989 miles, the engine has used 11 quarts of oil. Right after Katech did the work, oil use was 2000 miles per quart, but by early February, it had deteriorated to about 200 miles per quart. The engine has only been driven on the street and never tracked.
4) In road testing, during wide-open-throttle acceleration runs, in third gear from 1500-rpm to 6800-rpm, the engine suffers significant detonation resulting in a great deal of knock retard.
Did you happen to experience issue #4 before issue #3 reared its head?
Did you happen to experience issue #4 before issue #3 reared its head?
Unknown.
I didn't start logging data until I noted smoke out the exhaust at higher rpm during the first few WOT runs I made once the engine had 3000 miles on it and it wasn't until I started logging data that I noted a lot of KR. I started trying to calibrate the problem away, but I got to where I had parts of the high-octane table at 12° and was still seeing significant KR so, I decided this was oil ingestion and gave up.
Once Katech fixes whatever is causing the oil use problem, then I will, once again, start trying to do the WOT fuel and spark cals.
Last edited by Hib Halverson; 05-16-2018 at 04:15 PM.
The valve guides in my Street Attack engine are manganese-bronze parts manufactured by CHE. My opinion and that of WCCH, Katech and others is that, as long as guide/seat concentricity is held to .001 or less, Moldstar 90 guides are an unnecessary expense. On the other hand, if the lack of concentricity is greater than that, then maybe guides made of different material would offer better control of wear rates. In my opinion, it's better to have guides and seats which are concentric rather than use guides of a more expensive material.
If you really wanted to split hairs, theoretically, everything you had Katech do under the hood could be argued to be an "unnecessary expense"!
If Moldstar 90 is a superior alloy (durabilty/hardness and thermal conductivity) to berryllium copper (BeCu), and BeCu is superior to even manganese bronze, well then, isn't it logical that Moldstar 90 a superior alloy to bronze, as well? Cost would of course be a secondary factor.
Originally Posted by Hib Halverson
There's an interesting story about those heads. The set I put on that engine during the Engine Build Experience at the old PBC in Wixom, MI, were eventually replaced under warranty because of a problem with lack of concentricity of the guides and seats. After the warranty work, that set of heads were returned to GM. At the time, I was in the middle of writing a series of articles for Corvette Magazine along with another Corvette web site which covered the development of the LS7 engine as well as the guide wear problem. In the process of writing those articles, I was able to convince GM to share the testing and fault diagnosis information it gained about the car's original set of heads using one of the CMMs in the Inspection Department at GM's Global Propulsion Systems HQ in Pontiac MI. After GM was done with that, it was kind enough to send me back the disassembled heads. I appreciated the gesture because LS7 heads are serilized and their numbers are on the "build sheet" that went with the engine which I assembled at the Performance Build Center in 2012.
Bottom line, my Katech Street Attack now has the set of heads which I originally put on the engine at the Performance Build Center back in 2012.
That's pretty cool that GM sent you back your original castings and you were able to re-use them. I have a copy of my build sheet from the NCM but I don't see any serial numbers that appear to match up to the heads; you must have received additional paperwork with the PBC build. Cool beans.
Originally Posted by Hib Halverson
[FONT=Arial]
[COLOR=Blue]There were four issues that prevented my Street Attack build from living up to Katech's reputation for reliable, durable, performance-enhanced LS7s.
2) Anytime the engine was run over 6000 rpm, the A/C compressor drive belt would jump two grooves rearward on the crankshaft damper. If not repositioned before further high rpm operation, the belt would shread.
With #2, initially, because I never had the problem previous to Katech's work, I thought it was caused by the ATI crankshaft vibration damper Katech installed. I contacted Jason looking for a solution. He got in touch with ATI and they told him the problem was the A/C belt tensioner. I replaced the OE tensioner with an aftermarket unit from Continental, but to no avail. The the A/C belt kept jumping grooves. I bought a second tensioner, this one a Dayco. That didn't solve the problem, either. At that point, I decided it was unlikely this was a problem with belt tensioners.
The solution came from a likely source, this forum site after I posted a question about ATI dampers. Subsequently, CF Senior Member "double06" and I had a PM discussion about his experiences with the ATI Super Damper for LS7s. The original ATI design had no shoulder behind the A/C drive belt grooves. Apparently, this was the cause of a widespread A/C "belt throwing" problem which had ATI changing the design by adding a shoulder about .100-in high. The stock damper's shoulder is .160-in high. The belt I was using, a Continental Elite (which is the Goodyear Gatorback design which Conti now owns) had failed, so I reinstalled the stock belt which, I had kept as a spare. The stock belt stayed in place during repeated high rpm tests.
That got me thinking about slight differences in belt lengths. It was difficult to find effective length information about some of the belts on the market, but of belts for which I obtained data, the Continental Elite was the longest. I physically compared it to the OE belt, which is branded "Mitsubishi" and found it visibly shorter. Using listings on rockauto.com, I found the belt with the shortest effective length of belt makers which published lengths was a Dayco, so I ordered one. It didn't fit. There was no way, working by myself under the car, that I could get the Dayco on, so I went back to the OE belt. I'll save the Dayco to when I have someone to help me install it–one person underneath holding the tensioner back and another person working from the top to pry the belt over the A/C compressor pulley.
Bottom line: the problem was the "second design" ATI Damper and its sensitivity to belt length.
I ran into a similar issue with my AC belt when I did my heads and cam, too. The Dayco accessory belt I had bought to go with the main belt was just too short. I had it on my desk for a couple of weeks with measurements from a handful of comparable belts that I could find, but I just never got around to emailing Dayco. The Dayco accessory belt as I had measured was shorter than the four or five other that I had researched.
On the ATI balancer, I had just seen too many recent posts here on the CF of bad LS7 balancers from ATI, (with pics.) I'm not sure I would have gone with one had ATI given me one for free, there was definitely an issue that I only imagine they resolved with a subsequent design. I decided to go with the PowerBond Race Series balancer instead and am very happy with it. GM ought to have a contract with PowerBond to supply their balancers at least on high-performance applications such as Corvette and other motors with more than 400hp.
If you really wanted to split hairs, theoretically, everything you had Katech do under the hood could be argued to be an "unnecessary expense"!
Yeah, I guess your right.
If Moldstar 90 is a superior alloy (durabilty/hardness and thermal conductivity) to berryllium copper (BeCu), and BeCu is superior to even manganese bronze, well then, isn't it logical that Moldstar 90 a superior alloy to bronze, as well? Cost would of course be a secondary factor.
Trust me...I have researched the LS7 engine and the valve guide problem as well as or better than most here on the CF. I've talked to engineers at different companies which make valves, valve seats and valve guides. There is no arguement that Moldstar 90 has impressive material specs. My problem with it is that other materials make excellent valve guides at a lot less cost. Also, I believe that given guides and seats which are concentric within a thousandth, you don't need a guide like that. Now if you're going to work with heads having guides and seats which are not concentric, guide wear is going to be a significant problem and then maybe guides of MS90 might last a little longer. Also, if you were going to do a valvetrain with a tremendous amount of lift–far more than you'd ever run with a production based head–well then maybe you'd need guides made of Moldstar. That said, recently I talked to someone who builds blown fuel motors and he told me the guides they use are screw-in steel parts with manganese-bronze sleeves. I've also spoken with those at GM who build the motors for Corvette Racing and the heads on the 5.5L race engines do not use Moldstar 90 valve guides. Bottom line: Yeah, it's a killer material, but there are very few applications were it's really needed.
That's pretty cool that GM sent you back your original castings and you were able to re-use them. I have a copy of my build sheet from the NCM but I don't see any serial numbers that appear to match up to the heads; you must have received additional paperwork with the PBC build. Cool beans.
The head SNs were on some paperwork I got on the engine from the people at the PBC.
I ran into a similar issue with my AC belt when I did my heads and cam, too. The Dayco accessory belt I had bought to go with the main belt was just too short. I had it on my desk for a couple of weeks with measurements from a handful of comparable belts that I could find, but I just never got around to emailing Dayco. The Dayco accessory belt as I had measured was shorter than the four or five other that I had researched.
Oh great. We both have useless Dayco belts sitting on our work benches. Actually, I still think I can get that thing on, it's just going to take two people. One underneath the car holding the tensioner back and the the other leaning over and pushing the belt over the A/C compressor pulley.
On the ATI balancer, I had just seen too many recent posts here on the CF of bad LS7 balancers from ATI, (with pics.) I'm not sure I would have gone with one had ATI given me one for free, there was definitely an issue that I only imagine they resolved with a subsequent design. I decided to go with the PowerBond Race Series balancer instead and am very happy with it. GM ought to have a contract with PowerBond to supply their balancers at least on high-performance applications such as Corvette and other motors with more than 400hp.
Well...I'm kinda committed to the ATI at this point. Katech told me they use them because they've had the greatest success with them.
trust me...i have researched the ls7 engine and the valve guide problem as well as or better than most here on the cf. I've talked to engineers at different companies which make valves, valve seats and valve guides. There is no arguement that moldstar 90 has impressive material specs. My problem with it is that other materials make excellent valve guides at a lot less cost. Also, i believe that given guides and seats which are concentric within a thousandth, you don't need a guide like that. Now if you're going to work with heads having guides and seats which are not concentric, guide wear is going to be a significant problem and then maybe guides of ms90 might last a little longer. Also, if you were going to do a valvetrain with a tremendous amount of lift–far more than you'd ever run with a production based head–well then maybe you'd need guides made of moldstar. That said, recently i talked to someone who builds blown fuel motors and he told me the guides they use are screw-in steel parts with manganese-bronze sleeves. I've also spoken with those at gm who build the motors for corvette racing and the heads on the 5.5l race engines do not use moldstar 90 valve guides. Bottom line: Yeah, it's a killer material, but there are very few applications were it's really needed.
The way I look at is this. If I am to run Ti valves, which GM did from the factory on the LS7 intake valves, and I want to run bronze valve guides, I need to address the valves with the additional Molybdenum coatet stems. While that is a great solution, that's going to cost me just over $3,000 for 16 Ti/Mo valves. Instead, I can go with "overkill" Moldstar 90 valve guides for $600 and keep my stock Ti intake valves, and even upgrade at no additional charge to the superior Ferrea F2042P exhaust valves.
And AHP's tolerances on their valve jobs are .001" or under on valve seat run out (concentricity.) They take pride in their work and stand behind it. A lot of shops out there can't even get to that level of accuracy, let alone do it consistently. A superior valve job and a superior valve guide.
Originally Posted by hib halverson
oh great. We both have useless dayco belts sitting on our work benches. Actually, i still think i can get that thing on, it's just going to take two people. One underneath the car holding the tensioner back and the the other leaning over and pushing the belt over the a/c compressor pulley.
I found the specs on the a/c belts I briefly researched; measurements taken from the RockAuto website, I think. The Dayco is definitely the shortest. Interesting that the stock belts say Mitsuboshi.
The "Blue Bullet" is back at Katech. I shipped the car there using Pilot Transport about which I cannot say enough good things. I dealt with Angie Makin in Pilot's main office in Brighton Michigan along with Joe Sanchez, the truck driver. Back on Saturday the 12th a Pilot tractor pulling a 53-footer rolled up outside.
I pulled the BB out of the shop, while Joe unloaded a C7 he was going to drop later in the day over in Los Angeles, then he drove my car onto the top level and all the way to the front. Then he stuck the C7 back in behind my car.
He was on his way about 45-minutes later. Pilot Transport knows their stuff as far as moving collector and special interest cars around. Their price beat the other two I had quotes from, Reliable Carriers and Passport.
If you need to have a car transported, give Angie Makin a call at 248-486-3701 or email her at amakin@unitedroad.com. Thanks to Pilot driver Joe Sanchez for getting my car to Michigan safely.
The car arrived in Pilot's yard in Brighton on Friday the 18th and Katech picked it up there on the following Monday.
Katech emailed me yesterday to say that they will be starting work on the car late next week.
Obviously, I'll be very interested in what they find.
Once Katech fixes the engine, my plan is to, once again, fly to Detroit, pick-up the car and drive it back to California and, in the process, do some prerun work for the 2019 Corvette Caravan. Only this time, I'm going to drive as far as St. Louis then do an oil check. If the engine has used too much oil, I'll turn around and go right back to Katech.
Last edited by Hib Halverson; 06-24-2018 at 12:57 PM.
I had a conference call with Katech back on Wednesday. They gave me a preliminary report over the phone but the final report on the problems with my engine is pending. The guy at Katech responsible for that kind of thing, Chris, is off work because his Wife had a baby. After Chris comes back, completes the report and forwards it to me, I'll summarize it in a post here...probably be a couple of weeks.
In the meantime, congratulations Chris on your "family expansion"!
In other news....
I just finished an article for Corvette Magazine on the new ZR1's LT5 engine. I, also, did a piece for CM earlier this year on the car itself. While I love my LS7 because it's an NA engine that revs to 7100-rpm, I have to say that the new LT5 is impressive...everthing the LT4 could have been had the C7 ZO6 not had to meet European safety standards to allow its sale in the E.U. but I digress...I know this should be posted in a C7 forum.
Last edited by Hib Halverson; 06-24-2018 at 12:57 PM.
I had a conference call with Katech back on Wednesday. They gave me a preliminary report over the phone but the final report on the problems with my engine is pending. The guy at Katech responsible for that kind of thing, Chris, is off work because his Wife had a baby. After Chris comes back, completes the report and forwards it to me, I'll summarize it in a post here...probably be a couple of weeks.
In the meantime, congratulations Chris on your "family expansion"!
In other news....
I just finished an article for Corvette Magazine on the new ZR1's LT5 engine. I, also, did a piece for CM earlier this year on the car itself. While I love my LS7 because it's an NA engine that revs to 7100-rpm, I have to say that the new LT5 is impressive...everthing the LT4 could have been had the C7 ZO6 not had to meet European safety standards to allow its sale in the E.U. but I digress...I know this should be posted in a C7 forum.
Many of us are waiting to hear what the problem is and how Katech will handle it for you.
Many of us are waiting to hear what the problem is and how Katech will handle it for you.
So is there a C7ZR1 in your future?
DH
After researching those two articles and after watching the videos Chevrolet has been posting. I have to admit, it would be the first supercharged Corvette on my radar, but for now, working with the guys at Katech to get my C6 ZO6 straightened out is about all I have time for Corvette-wise.
Last edited by Hib Halverson; 07-16-2018 at 03:37 PM.
Heard from the Katech folks this morning. They are going to pull the motor, tear it down and inspect/measure everything. I'll have the report in about two weeks.
Last edited by Hib Halverson; 06-28-2018 at 01:06 PM.
I have the report from Katech. It came as a .pdf and has "Katech Confidential" displayed on every page, so I can't post the specifics, but I can summarize parts of the report.
In mid-May, just before I shipped the car back there, I ran an oil use test lasting about 300 miles. I put a quart in 200-mi after the test started and then another quart at about 100-mi after that. Katech confirmed that level of oil use just prior to their teardown with a road test of their own which showed about 100 miles per quart.
Katech ran the car on the chassis dyno and found it down on power. They put the original calibration back in the ECM and some of the power loss came back, but it was still 50-hp down from what it was when the car left Katech last on 7DEC2017. They also noted the engine exhibited knock retard.
The report states the MAF and spark table calibrations which were problematic. Starting on 28FEB2018, after Katech emailed me that they were unable to continue to send me revised calibration files, I made changes to both those tables. Prior to that, starting in early January, I had, also, made calibration changes, but none were with MAF or spark. Any calibraton change voiids the warranty Katech extends to Street Attack customers.
They ran an exhaust pressure test and found excessive backpressure on both sides. Both cats are restricted. They borescoped one of them and observed spots where the substrate had begun to melt, an indication the air:fuel ratio was lean under high load.
After getting the engine apart, Katech found the crankshaft, bearings, connecting rods and the valve train are all ok.
The crosshatch in all bores is just about worn away leaving a near-mirror finish. Bore wear is about .001-in. on all cylinders. All the piston tops were wet with oil. All the rings were severely worn. The Katech guys told me that an air:fuel ratio under load which is excessively lean or excessively rich can cause that type of bore and ring failure. Poor air filtering can, also, cause that level of wear.
Combustion chambers and valve faces are wet with oil and sooty.
The Intake manifold had dirt/debris inside. The air filter had been damaged, by my blowing through it with shop air when I cleaned the filter about a month before shipping the car to Katech. In talking with them and the filter vendor, I found out doing that to oiled-cotton filters is a bad thing.
Katech uses GM's warranty benchmark for excessive oil use which, in brief, states that oil use more 2000-miles-per-quart indicates an engine mechanical problem.
My "Street Attack LS7" has 4873 miles on it since it was built by Katech in late 2017. In the first 2851 miles of operation, before I violated Katech's warranty by making calibration changes in early January, the engine used two quarts of oil. It used a quart in the first 2070 miles and a second quart 781 miles later, which maths-out to 1380-miles per quart. From then on, oil use accelerated until I shipped the car back to Katech in mid-May.
In a conference call I had early last week with Katech's top managers, they were unable to explain how the oil use got started in the first 2900 miles. Katech's guys said that they have built many Street Attack engines in the last 12 years and have never had an engine with a problem like that.
The next step is for Katech to send me a quote on what's necessary to repair the engine and what it will cost to do that.
05-07-2018, 01:43 PM
