Question for you guys:

This is my first FI car and I just got back from a fun weekend at Road Atlanta. During the last session @ 4:20pm (about an hour break from the previous session) going through the esses and coming out of 5 the turbo sounded louder than it had all weekend. Then coming out of 7 onto the back straight it sounded loud again and when I reach 5000rpm (4th gear) it seemed to fall flat on it's face.

I did notice during my last 2 sessions that it was taking me longer and longer to reach speed on the back straight. Earlier in the day I was reaching 120mph halfway to the black flag station, later I was struggling to reach 115mph by the flag station.

I will post a video of it when I get some time to edit it down. You can clearly hear a difference in turbo volume from the lap previous to the issue. I just want to make sure I didn't damage the turbo or anything else. After the track idle was fine and cruising the highway home there were no unusual sounds.

Only mods on the car are listed in my sig. Running stock intercooler and pipes.

~Shaun

 

What were all the temps? Ambient, oil, water, track, driving 10/10th's?

 

Dunno about the louder sounds. But:

A majority of the time, the track will be the fastest at like 10am in the day. That's usually the best combo of on-track temp (not insanely hot yet), ambient temps (still cool) along with your tire temps warm enough for grip and the car hasn't been hammered on (hot) all day.

After that 'sweet spot', the track usually slows down. We as newbs tend to keep picking up speed as we learn better lines and develop better skills so it'll mask that. So that's my guess.

 

Sounds more like you may have a leak of some sort. Could your bov or bpv be opening up? That could cause a loss in power, but not mess with your idle. If you had a vac line popped off, your idle would most likely be funky. I'd still go over every little vac line just to be sure.

Do you have a boost gauge to see what's going on when it's making this sound?

 

Unfortunately I don't have any aftermarket gauges in the car right now (working towards getting some). I took it easy on Saturday and then I put the hammer down a bit on Sunday. Sunday ambient temps in the afternoon were reaching 75-80. I am not sure what the track temps were. The dummy temp gauge in-car never went above halfway.

I was probably driving @ 7-8/10 in the afternoon. I was on street tires and street pads so I was letting off early prior to corners and working on carrying speed through the corner (which is why I have melted the outer edge on my front tire).

My lap times on Saturday were 1:58's to 2:00. Sunday I ran a best of 1:51.1 and averaged 1:52-1:55

I actually think I may have a boost leak because on the way home I hit boost once and it sounded like I had an open dump. I will dig into next Monday when I am off work (no time this week) and post a video tonight.

 

It is essential for even club racers who runs longer then 13 second at the time to have a boost ~ oil temp ~fuel pressure gauge or air amd fuel gauge at least

 

Actually I think that is your biggest clue that an exhaust leak pre turbo is likely what is causing the issues. When you go through heat cycles on a road course, things that are fine on the street can be massive leaks after multiple track sessions. If you have a leak pre turbo the boost won't build as fast and eventually if it gets bad enough your peak boost will start dropping as well. Then when everything cools down it might seal up the leak somewhat or make it worse depending on the different materials they are made of and how they are fastened together.

I've had this happen to me first hand, and a 2mm seperation between my Tial WG and turbo housing caused boost to build slowly at lower RPM's and peak boost started to fall off a bit until higher RPM's. Then I had enough exhaust hitting my firewall to cause a smoldering fire which almost burnt the car down. You could definitely hear the turbo louder because the noise of the turbo was not being muffled by the exhaust.

Let me know if I was right!

 

Good to meet you and your wife this weekend Shaun. Hope you figure out the issue without too much trouble. A 51 with those tires and brakes on a nearly stock 8 is moving it.

 

Thanks Jim... just hope I didn't move it too much. Enjoyed meeting you as well.

Hiboost: I don't think it is a pre turbo leak, but I will be checking regardless. I made one test run today and the power feels like it normally does down low, and it sounded like it was coming from the LICP. I am hoping that just a clamp came loose.

Robevo: I am planing on getting at the very least a boost guage shortly. If I were to run a boost~wideband~oil temp guage would I need to run a water temp of an oil pressure guage as well. I only want to run 3 gauges-4 max.

 

Well I found what was causing my issue, a 1" split on the inlet pipe off the endtank on the hotside. Currently getting an OEM replacement.