High Boost Testing!!
High Boost Testing!!
High Boost Testing!!! :rock: :syty:
I can definitely testify to the fact that these heads and cam do allow you to run more boost on pump gas........but just a little, maybe 2-3 PSI more. I think I was able to run ~18 PSI with areas of 0.0 knock now on pure 93 octane. I CERTAINLY am not able to run any significant amount more timing than I could with my stock heads. And neither could the only other vortec-headed truck I tuned personally..... :roll: Do I believe vortecs "greatly reduce detonation"? Not really. Not in the sense that, if your truck was knocking on stock heads, it ain't gonna be magically fixed with vortecs. I just haven't seen the evidence. :2cents:
After getting the WOT AFR close to flat around 11.0-11.4 I decided to step it up and turn on the (SMC dual nozzle) alcohol injection system and start leaning out the top end and adding boost.
Man, this thing is freakin' awesome!! The PT51 turbo hits so hard now, it will squeal the tires from a 10-15mph roll!! And these tires (stock rims) got me a best 1.630 60' so it's not like they are some tight sidewall 18" that turn over easy, either! When you floor it now, you gotta have both hands tight on the wheel and keep it straight because the front (and rear) tires want to make it skate all over. I think this is "the Syclone dance" the foreign SyTy owners talk about.
Gave a handful of people rides already, if you give it even 3 PSI on a launch, it will burn the tires all the way through 1st and into 2nd (never did that before!) The boost just hits so hard, I think people who seriously over-turbo their engines are making a huge mistake, it's so much more FUN when you can get full boost at half throttle!
On the flip side, I might be starting to feel the drawback of the small turbo.
I get 21 PSI on the spoolup spike, but by 5400 RPM it's down to 16.0 PSI!! My boost control used to be within 1-2 PSI, now it's just garbage. I ported the wastegate somewhat conservatively after TurboTony warned me that too much porting can cause the wastegate to open on it's own. That's kind of how the boost is responding, at high RPM it's opening too much. Or maybe the turbo is just out of flow? My DM dynos hit a new all time high of ~585 HP (720 LB-FT torque!), right what the PT51 is rated at. Is boost dropping at high RPM a sign of a too-small turbo? I tried adjusting the wastegate rod tighter but it doesn't seem to be helping. Even though the boost is fluctuating +/- 5 PSI, my AFRs are tuned flat to 10.9-11.4.
I ran through a gallon of methanol already. This project feels like such a success at this point, that I broke out the $50/750mL single malt "Cask Strength" scotch :silly: :drinking:
I was giving a friend a ride today and on a launch it hazed the tires and then BOOM! The engine went silent and I thought that was all she wrote. My heart stopped and I looked at the tach and I thought it was dead. Then I realized it was still at 900 RPM, and I just blew an intercooler hose off my (inadequate) 2nd alky nozzle mount. I fixed it but I realized that with 250 miles on this build, I already had enough fun to make it worth it if it lets go tomorrow. :lol:
Timeslips Soon.....?
I also wore an LS1 brake pad down to nothing so I'm doing a brake job today (are ceramic pads good for street/strip?), and the dragstrip is open on Tuesday for the last weekday of the year... I'm gonna try and make it so I can finally get a timeslip faster than the 11.79 I ran in ..................2003!! :? :dunno:
![Quickstop [UK]](/data/avatars/m/5/5165.jpg?1570199786){kind=avatar}
