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Bashed on the car pretty hard again over the weekend and I now have some pretty serious slop in either the transmission or the rear diff. Time to put it up in the air and see where it is coming from. The MV5 I put in it was a high mileage unit, but it was the ONLY one I could find in CO so I went with what I could get my hands on. Now that I'm in TX I'm hoping they will be easier to come by and I will get on car-part.com once I know for sure it is not the diff..which was impossible to find in CO.
Just wanted to post up a quick update on the status of the car. Wifey got me a GP8 for my birthday so I am finally able to get a bit of footage on the track. I am still playing with the DL features of the Solo2 DL but it is a great tool for learning and I wish I had bought one a long time ago. Getting the video and data merged in RaceRender was pretty easy too so no need to by that crazy overpriced SmartyCam if you don't want to. Sorry there is no audio. Still trying to figure out how to blend the audio into RaceRender...
I was finally able to get the car to MSR Houston for the first time which has a decent back straight to test the top end power I was shooting for with the turbo. Here is a short clip of the 1st qual session for the time trials event. The day started off with tons of rain and the circuit was CRAZY SLICK! It didn't help at all that I had never been on the track before either. I could not get a single clean lap due to all the slipping and sliding but I did manage to keep the car on the pavement which is more than could be said for many of the others that morning. The rain finally quit and the track had dried up just enough to get some heat and grip in the tires but it still felt "greasy" so I was only pushing it about 75-80% in the corners in the video. If you look close you can still see some of the standing water I was trying to avoid in the video. Car felt a little unsteady around 120ish so I was breaking WAY early before the slower right sweeper before the tight right turn after the straight. If I can get the rear aero sorted out I can carry a TON more speed at the end of the straight. Good news is that even at 120 the turbo was in full HELL YEA mode and still pulling hard by the time I needed to get out of the gas and on the brakes. Although I was taking it easier and short shifting I had absolutely ZERO cooling issues now that the rear exchanger is installed so that makes me and the car very happy. I did almost run her out of gas tough and got a power blip in a corner which forced me to end the qual one lap early and head to the trailer for fuel.
After reviewing the footage and the laps I was able to get in while it was drier I think I can get a 1:45 out of the car pretty easily. Bottom line... I am super happy with the car and the turbo I picked just so happened to be a perfect fit for what I wanted to achieve. It is not crazy overpowered on the bottom end running 245 100TW tires and JUST...KEEPS....GOING on the top.
**EDIT**
Had the boost dialed back to 5psi max and redline set to 6500 for this event.
Not sure what happened. Audio in the GP footage but when I ran it through RaceRender it got stripped out. Takes a bit of time to generate the video with the overlay so I just said screw it. When I have some time I will try to generate another video that will have the audio.
You get your new exhaust yet? Can't wait to see how it sounds!
That thing should not be unstable at 120. Definitely something going on. All I have is the front dam and I was stable to 135 (gear limited) but fast completely glued at 120.
Not sure what happened. Audio in the GP footage but when I ran it through RaceRender it got stripped out. Takes a bit of time to generate the video with the overlay so I just said screw it. When I have some time I will try to generate another video that will have the audio.
You get your new exhaust yet? Can't wait to see how it sounds!
Muffler is being built now, should have it next week.
That thing should not be unstable at 120. Definitely something going on. All I have is the front dam and I was stable to 135 (gear limited) but fast completely glued at 120.
Agree and it was not really "unstable" at speed but just felt a bit too light at twitchy for me to push it on a slightly wet track. It was not uncontrollable at all and I just need to find a place where I can do some back-to-back testing with the rear wing. I had the AoA dialed way down to see how she did in a straight line and I just need to dial in more angle in the GT 250. Only testing will tell the tale. I also have a bit of toe-out in the front and toe-in dialed into the back which make the turn-in amazing but is probably contributing to the current "twitchy" high-speed habbits.
So at the end of the last track day I was hearing/seeing some odd detonation and I could feel the car trying to pull a ton of timing coming out of the corners. The WB O2 was all over the place so I logged a few runs and noticed that just the driver side bank was really lean.
I started my investigation with the plugs. Pulled the passenger bank and the looked like they were running rich. Started pulling the driver side plugs and #2 did not want to come out. Worked the plug out slowly and once it finally came out it was clear it was running lean. #4 would not budge so I skipped it. #6 finally came out but took some time and had what looked like alu melted around the insulator. Tried #4 again and SNAP....the worst case scenario....plug snapped off in the head. These were all brand new one step colder Brisk plugs.
I found a cheap low milage Camaro LFX locally so ran and grabbed it because a whole engine is not much more than just a head. This is one of the best thing about the LFX over a V8!! Cheap and everywhere.
Rather than swap just a head I decided to pull it and swap motors because I needed to upgrade my slipping clutch anyway. Curiosity was killing me so I started to pull the head off the old motor while I wait on my new clutch and flywheel. I pulled the timing cover off and there was no need to go any further. It was the left bank timing chain that caused the issue and it all made sense now...
The additional power and torque stretched the OEM chains and the driver side bank was able to hop one tooth(verified by chain/cam indexes). The ECU was trying desperately to use the phasers the keep the timing correct but it couldn't. Driver bank went lean so it was dumping fuel to try and keep things in check. Only odd thing was that it never threw a cam code so I'm guessing it was stretching just enough that the cam sensor was being fooled.
I'll post more pics once I have a chance to dig deeper but do yourself a favor and install a good aftermarket timing set in your LFX the first chance you get. They are a known weak point even when you are not running boost.
I originally decided to replace my MV7 with an MV5 and was going to go with a monster clutch. Spoke with SPEC to get a total cost comparison since Ryan is having good luck with his after moving to an MV5. Turns out that SPEC now has a specific part number for a 2009 CTS 3.6 which is the spec I used to find an OEM dual mass that worked fine other than not enough clamping force for my build. Had a long chat with SPEC and he indicated that they incorrectly assumed the flywheels were the same.
Since the frame rails are different and I have a floor drop, a swap will be a pain. Add in the cost for all the other stuff needed and it just made sense to stick with the MV7 if there is an aftermarket clutch option that will actually work. Not really much to go wrong in a manual gear box so one spare should be sufficient. The only reason to get away from the MV7 was the oem dual-mode clutch was a 100lb turd and good aftermarket clutches wouldn't disengage when paired with the MV7. I will provide part numbers and results once i have it in and properly track tested under boost.
Still researching the "best" timing chain based on failures after replacing them. I'll post up the one I go with when I post the parts I use in the rebuild.
That brings me to future plans. I am going to rebuild my old motor with better guts/springs/cams and I have found a company that makes a HPFP that states that it provides 60% more fuel that the Hitachi one found on the ATS-V. That should give me a chance to play with more boost if I want to and way more reliability while running lower boost.
I'd be very wary of giving SPEC any money. It's kind of hard to determine with our order of events (bad dual mass, spec flyweel + sprung center clutch, springs evacuated, replaced clutch, didn't shift as nicely as when the dual mass wasn't totally trashed, went back to dual mass - still not easy shifting but way better than spec). I think there might be some input shaft damage on our MV7 from the spec adventure, and I'd like to see if the MV5 holds up or starts to go south with spec setup.
08-29-2019, 10:34 AM
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