Track Results from a PT7675 CEA to a PT8285 CEA BB
04-27-2015, 10:32 AM
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Track Results from a PT7675 CEA to a PT8285 CEA BB Hey All, I haven't posted much on my build in a while although not much has changed. Over the season last year I was chasing down suspension issues and finally got that sorted toward the end of the year. I made a two passes and ran a 9.81 and a 9.75 @140mph with a 1.39 60'. I was pretty happy with the results but had to push the PT7675 to 21psi to get there.
Attachment 723318
[YOUTUBE]dFbLtECdkOI[/YOUTUBE]
My MPH didn't seem to improve and I believe it was due to the 3" downpipe choking back the turbo over 15-16lbs. I decided over the winter that I wanted to increase my downpipe and give it another go to see if that helps with higher boost passes. This would require me to get a turbo Kmember and have my buddy TurboJoe@Straightline make the downpipe. I could have done a fender exit exhaust but it's not a race car or anything
. I was planning on pushing the little PT7675 as far as I could but, well, my buddy with a badass supra was selling his old turbo so I asked if I could borrow it. It's a PT8285 CEA BB turbo and said if it fits it sits. Well it's a huge bitch for being a T4 but it fits very tight with minimal messaging.
btw, I've since replaced the elbow on the compressor to an aluminum on so it wouldn't collapse.
Attachment 723323
Attachment 723324
With the kmember, turbo, and downpipe in place I decided that I'd be best off getting a wideband and take on the tuning. I had an awesome tune from Mikey@Straightline when I had the PT7675 and he helped guide me through the process a little and I researched online for some techniques. More than anything I just wanted to dial in my AFR and add a little timing and boost here or there. I picked up a LM2 wideband and it integrates well with my HPTuners device. After setting up my config file to read an AFR error percentage histogram (basically compares you commanded afr vs actual) I found that the tune wasn't that far off. 5-10% during the top of a pull. I command .85 at WOT. Good enough to run at the track and tune from there at least low boost until I feel comfortable with the VE table
So fast forward to yesterday. My plan was to gauge how well the turbo is working efficiency wise. I wanted to run better times and mph on less boost and the same timing. Just seeing if the efficiency of the turbo and larger downpipe was going to produce results while dialing in VE. I left my shocks settings front and rear as the same when I ran last year the 9.7 and 9.8.
Honestly this is a personal hobby but at some point I felt like I was in over my head. Just the little things. I've started to take safety as a big concern. I got a role bar, fire extinguisher, fire jacket and 5 point camlock harness recently. I feel much more safe in the car as I said if I did something stupid while wrenching at least I feel safe in the car to push it. If I need something fabricated I'll have a shop like straightline help but otherwise I'm doing the work and I'm a computer nerd by trade with no prior experience with this sort of stuff.
My first pass I was a bit nervous. I did a week burnout and got up to the line. Car launched hard but didn't have any heat in the tires and immediately kicked the rear end out and sent me into the other lane. I let out and straightened it out but I know the C6 vette in the other lane ruined his pants. I hot lapped as they ran T&T back to back so I sobered up on the return lane for another pass.
Pass 1
My buddy helped me in the box and stage up. Got my wideband plugged in, hptuners plugged in, and hooked up and recording. I got some good heat in the tires and felt better. I pulled forward and broke the beams. I was anxious this time and trying to stage by brake torquing into the beams and didn't hit my tbrake. I need a bump box lol. Got back in the beams and loaded up the brake. I worked up about 8psi and let lose. Front came up and back down pretty manageable and the car felt solid and on rails. First pass was a 9.49@143.08 1.35 60'. I was kinda shocked but the car did feel like it's ran its fastest pass up to that point.
So i pulled off and took a look at the logs. My buddy gave it a look as well and we determined that the pass looked good and healthy. No KR anywhere and no odd dips or misfires. I went ahead and put in 3 more degrees of timing to bring it up to 22-23 and left boost alone but upped my 2step 200 more rpm. The odd thing was it was on spring pressure with a 12psi spring but I was sitting at 16 psi in my logs. Maybe my wastegate isn't large enough and overboosting.
Pass 2
Well I got back in line. Had a great burnout and pulled up to the line. Staged up and hit the 2step/tbrake. I actually tried to cut a decent light and the car left as hard as it ever had. Next to me was the Blackout Racing red cobra. Thing is a beast!!! So i make a solid pass and get my slip. The time/mph were slightly better at 9.42 @143.74mph with a 1.29 60'. Not a bad 60' considering the car is a full weight, full interior, and full exhaust. If I weren't so stubborn I could have helped myself out, but I want to get times for the car that I drive on the street. Not a shell of what it is and then add all the weight back.
Attachment 723328
Got back to the truck and pulled out the laptop to see how it's doing. We looked it over and the logs looked good. I made some changes to ve to dial in the afr. My boost is still hovering around that 16psi and it was a little erratic between 13-16psi. Keep in mind that the controller is completely disabled still so I'm going off of spring only. I decide to put on the boost controller and try a lower setting duty cycle. i added another 100rpm to the 2step and got the car back out. I did a really good burnout and moved up to the beams.
Pass 3
Got on the 2step/tbrake and built up the boost to about 10psi and let lose. The car went heals to Jesus and I **** my pants. I'm getting pretty use to the front traveling up and seeing nothing but sky but when I started to feel like I was rotating backward I let off the throttle a little bit to try and get the front down. It started to come back down and I immediately got back on it to try and save my underside from pancaking and keep the rear planted. I did a couple bounces after that and stayed in it all the way down. My drivers side headlight cover came lose and as I was going down the track it did this awkward dance of folding backwards and bending up really good. There were a flurry of fbombs being tossed around in that car that are still hovering somewhere over Lake Michigan. The headlight cover was just added entertainment. On that pass the car ran a 9.6@143.79 with a 1.37 60' and looking at my logs my boost settled at 17psi but stayed solid compared to the base runs that were erratic. Maybe the controller being on is regulating the boost much more than just relying on the spring. I'd imagine if didn't have to peddle it on the launch it could have gone 9.2's maybe. Anyway while on the return road they send a guy down the track to see if I broke anything off. Track was clean. I get my slip and head to the truck. Outside of the headlight bracket and a couple scuffed exhaust tips the underside was fine.
And now for a pic and video of that pass. I was told it was definitely a scene worth watching. I couldn't tell you because I was ruining a perfectly good set of pants. Courtesy BlackOut Racing. Thank you guys for being cool and letting me learn some things.
Attachment 723329
Next time out I'll bring the boost up to 20 psi and soften up my front shocks a little to keep the front down. Now might be a good time for travel limiters since this seems to be a theme.
In short the PT8285 and larger downpipe is allowing me to run faster times at more mph with 6psi less boost and all other things equal.
Attachment 723318
[YOUTUBE]dFbLtECdkOI[/YOUTUBE]
My MPH didn't seem to improve and I believe it was due to the 3" downpipe choking back the turbo over 15-16lbs. I decided over the winter that I wanted to increase my downpipe and give it another go to see if that helps with higher boost passes. This would require me to get a turbo Kmember and have my buddy TurboJoe@Straightline make the downpipe. I could have done a fender exit exhaust but it's not a race car or anything
. I was planning on pushing the little PT7675 as far as I could but, well, my buddy with a badass supra was selling his old turbo so I asked if I could borrow it. It's a PT8285 CEA BB turbo and said if it fits it sits. Well it's a huge bitch for being a T4 but it fits very tight with minimal messaging. 
btw, I've since replaced the elbow on the compressor to an aluminum on so it wouldn't collapse.
Attachment 723323
Attachment 723324
With the kmember, turbo, and downpipe in place I decided that I'd be best off getting a wideband and take on the tuning. I had an awesome tune from Mikey@Straightline when I had the PT7675 and he helped guide me through the process a little and I researched online for some techniques. More than anything I just wanted to dial in my AFR and add a little timing and boost here or there. I picked up a LM2 wideband and it integrates well with my HPTuners device. After setting up my config file to read an AFR error percentage histogram (basically compares you commanded afr vs actual) I found that the tune wasn't that far off. 5-10% during the top of a pull. I command .85 at WOT. Good enough to run at the track and tune from there at least low boost until I feel comfortable with the VE table
So fast forward to yesterday. My plan was to gauge how well the turbo is working efficiency wise. I wanted to run better times and mph on less boost and the same timing. Just seeing if the efficiency of the turbo and larger downpipe was going to produce results while dialing in VE. I left my shocks settings front and rear as the same when I ran last year the 9.7 and 9.8.
Honestly this is a personal hobby but at some point I felt like I was in over my head. Just the little things. I've started to take safety as a big concern. I got a role bar, fire extinguisher, fire jacket and 5 point camlock harness recently. I feel much more safe in the car as I said if I did something stupid while wrenching at least I feel safe in the car to push it. If I need something fabricated I'll have a shop like straightline help but otherwise I'm doing the work and I'm a computer nerd by trade with no prior experience with this sort of stuff.
My first pass I was a bit nervous. I did a week burnout and got up to the line. Car launched hard but didn't have any heat in the tires and immediately kicked the rear end out and sent me into the other lane. I let out and straightened it out but I know the C6 vette in the other lane ruined his pants. I hot lapped as they ran T&T back to back so I sobered up on the return lane for another pass.
Pass 1
My buddy helped me in the box and stage up. Got my wideband plugged in, hptuners plugged in, and hooked up and recording. I got some good heat in the tires and felt better. I pulled forward and broke the beams. I was anxious this time and trying to stage by brake torquing into the beams and didn't hit my tbrake. I need a bump box lol. Got back in the beams and loaded up the brake. I worked up about 8psi and let lose. Front came up and back down pretty manageable and the car felt solid and on rails. First pass was a 9.49@143.08 1.35 60'. I was kinda shocked but the car did feel like it's ran its fastest pass up to that point.
So i pulled off and took a look at the logs. My buddy gave it a look as well and we determined that the pass looked good and healthy. No KR anywhere and no odd dips or misfires. I went ahead and put in 3 more degrees of timing to bring it up to 22-23 and left boost alone but upped my 2step 200 more rpm. The odd thing was it was on spring pressure with a 12psi spring but I was sitting at 16 psi in my logs. Maybe my wastegate isn't large enough and overboosting.
Pass 2
Well I got back in line. Had a great burnout and pulled up to the line. Staged up and hit the 2step/tbrake. I actually tried to cut a decent light and the car left as hard as it ever had. Next to me was the Blackout Racing red cobra. Thing is a beast!!! So i make a solid pass and get my slip. The time/mph were slightly better at 9.42 @143.74mph with a 1.29 60'. Not a bad 60' considering the car is a full weight, full interior, and full exhaust. If I weren't so stubborn I could have helped myself out, but I want to get times for the car that I drive on the street. Not a shell of what it is and then add all the weight back.
Attachment 723328
Got back to the truck and pulled out the laptop to see how it's doing. We looked it over and the logs looked good. I made some changes to ve to dial in the afr. My boost is still hovering around that 16psi and it was a little erratic between 13-16psi. Keep in mind that the controller is completely disabled still so I'm going off of spring only. I decide to put on the boost controller and try a lower setting duty cycle. i added another 100rpm to the 2step and got the car back out. I did a really good burnout and moved up to the beams.
Pass 3
Got on the 2step/tbrake and built up the boost to about 10psi and let lose. The car went heals to Jesus and I **** my pants. I'm getting pretty use to the front traveling up and seeing nothing but sky but when I started to feel like I was rotating backward I let off the throttle a little bit to try and get the front down. It started to come back down and I immediately got back on it to try and save my underside from pancaking and keep the rear planted. I did a couple bounces after that and stayed in it all the way down. My drivers side headlight cover came lose and as I was going down the track it did this awkward dance of folding backwards and bending up really good. There were a flurry of fbombs being tossed around in that car that are still hovering somewhere over Lake Michigan. The headlight cover was just added entertainment. On that pass the car ran a 9.6@143.79 with a 1.37 60' and looking at my logs my boost settled at 17psi but stayed solid compared to the base runs that were erratic. Maybe the controller being on is regulating the boost much more than just relying on the spring. I'd imagine if didn't have to peddle it on the launch it could have gone 9.2's maybe. Anyway while on the return road they send a guy down the track to see if I broke anything off. Track was clean. I get my slip and head to the truck. Outside of the headlight bracket and a couple scuffed exhaust tips the underside was fine.
And now for a pic and video of that pass. I was told it was definitely a scene worth watching. I couldn't tell you because I was ruining a perfectly good set of pants. Courtesy BlackOut Racing. Thank you guys for being cool and letting me learn some things.
Attachment 723329
In short the PT8285 and larger downpipe is allowing me to run faster times at more mph with 6psi less boost and all other things equal.
04-27-2015, 10:49 AM
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It's got a 3.54 gear and the PT7675 had a 3" downpipe and now the PT8285 has a 4". Both with cutouts and connected to my magnaflow catback. Only other difference was the kmember to accommodate the larger downpipe.
04-27-2015, 10:59 AM
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Yeah the next time I'm out probably. I want to drive it this summer so come fall time I'll turn it up and see if it holds. Motor has together been 4 seasons so far so knock on wood. Not bad for an ls1 aluminum block
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04-27-2015, 01:58 PM
#16
Awesome runs man! I wish you lived closer, our cars next to each other would be quite the show! lol New turbo seems to be working well. Next thing on the list for me is turbo and injectors. This little 73mm is maxed the $%#@ out unfortunately. Congrats again on the 1.2X sixties, huge wheelies, and mid 9's. 
04-27-2015, 04:41 PM
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Great update, Great writeup, and great work.
Love seeing updates like this. Your hardwork is paying off greatly. And it shows. Love the full on street car ride too. Im going for the same. I can see why people do it, but i dont want a swiss cheese car.
Good Job.
Love seeing updates like this. Your hardwork is paying off greatly. And it shows. Love the full on street car ride too. Im going for the same. I can see why people do it, but i dont want a swiss cheese car.
Good Job.
