spurvo

Wow! So I just finished the temp gauge mod. Now the gauge reads more or less cold all the time. Need to readjust, no biggie. I noticed that the fan comes on just under needle pointing towards the middle, and turns off at the cold normal mark, about what I expected. Anyway, the mod was easy, and nice to have a functional gauge.

What I really wanted to say was I got home and performed my daily pop-the-hood-for-an-hour mod. I happened to look over the pass fender, and a funny light caught my eye. I thought it was the streetlight. Nahhhh... couldn't be!

Yep. The pre-cat, right around the O2 sensor, was GLOWING. Nice red color, kinda like a coke can. I had NOT been on the turbos on the way home, and shut it off with the temp gauge around where the fans will shut off if they've been cycled with the lights on (otherwise known asn approx 195 F). No wonder the rubber hoses have turned to hard plastic...

The pettit dp should be here by the weekend. Chose that one 'cause I'm a masochist. Like to hurt myself. Anyway, just thought I'd mention this little observation...

Snook

iTrader: (12)

drive the car hard for about 10 min them come back and park it and start to install the downpipe.

tookwik

dubulup

Your gonna love the DP!

turbojeff

iTrader: (30)

It shouldn't be glowing after a mellow drive.

Your pre-cat is plugged and/or your car is running to rich. It could be bad plugs and/or wires causing the engine to leave some fuel unburned in the exhaust.

Jeff

maxpesce

Also a BAD O2 sensor will cause you to run very rich in Closed Loop mode (Part Throtle / No Boost) which in turn will cause the Pre-cat to get VERY hot.

ttpowerd

got to love a dp although I have seen them glow red before too Run it hard consistantly and it will glow

FDjunkie

Remember the little sticker that says not to park in tall grass...

Garrett

I love that name, downpipe

To think about it, I love my downpipe

Garrett

spurvo

Hmmm... too rich would give black smoke, yes? Also have driveability problems, which I don't. So far...

Plugs replaced this last weekend (all nines, for saftey, even though stock).

Now, the pre-cats being clogged... yeah, that may be. I've noticed that even though the car is boosting to ten, it doesn't feel as fast as when I first got it. I recall stepping into it in fifth on the freeway and getting faster REAL hard, now it just kinda winds up there. Of course, would I still be boosting properly (10-8-10, YAY!) with a clogged pre-cat? Hmmm...

RonKMiller

Downpipe = and

YayeR

i musta missed that one

spurvo

HA HA!! bringing back an old thread... (note that this is pretty long, so don't bother if you don't care!)

So I stuck a temperature probe onto the turbo housing when it was so hot it was glowing (this is after the DP has been put on, and with the turbo housing heat shield left off for now). I was measuring 450 celsius (842 F), which is nice and fine for an idling temp, given WOT temps are in the 850 celsius (1562 F) range.

Anyway, what I noticed was that the turbo housing stayed hot, even with the engine running at 177 F (the thermostatically controlled minimum temperature). I was keeping that temp low using the fan mod to keep the fan on low, keeping the t-stat closed, engine idleing. Now, when I turned off the fans, two things happened. First, of course, the engine temp went up (as measured from the stock temp sensor location. I linearized the gauge). But the turbo housing temp went DOWN! I realized that the thermostat closing must close the turbo cooling lines off from the radiator (you may remember me asking about this in another thread). So, to check, I turned on the fan. The turbo housing went down to about 400C (752 F) then stopped dropping as soon as the engine reached 177. The turbo housing temp actually started to rise again. I turned off the fan, and once again, the turbo housing temp dropped as soon as the t-stat opened again. Hmmm...

So I now use a modified turbo-timing type of shutdown. Typically, when I park the car after returning home, the engine temp is at 177-180. I let the temp come up by idleing at 1000 rpm to about 200 F. Then I turn on the fan and cool down to 180 again. I do this three times, and the turbo housing is at 360 C (680 F). This whole process only take three to five minutes. That's almost 100C (212 F) cooler than the temp it sits at when running on the freeway (another place where the t-stat is fully closed). I've noticed that after shutdown, I get almost no heatsoak in the engine (where the temp rises above the level seen at shutoff). I've also noticed that the turbo housing temp doesn't change at all if I run the fans after shutoff. It just cools down the same rate as if the fans weren't on. Just wondering how that fits into the whole turbo timer/fan mod thing... bring on the flames!!

Of course, temps go down faster if the hood is open. Even just popping it without opening it fully helps. Anyway, just thought I'd throw in my $0.02 about what's going on. I know there is less boiling of the coolant and cokeing of the oil because of this, though still would love to fiind a way of bringing the turbo temp down further before shutoff.

Thanks for getting this far!! Any comments? About to welcome me to last week? Got any ideas as to how we might re-route the cooling system to force the hot coolant from the turbos into the radiator first? I think the mixing temp differentials may cause local hot spots in the radiator, so the t-stat may remain closed but super heated coolant in the rad be a problem. Hmmmm...

Import Convert

The Pettit DP is an easy install. I didnt have to remove any studs or jack up the motor. Just slid right on.

spurvo

I totally agree. I swapped the studs since they came right out of the turbo housing (turbo replaced 15K ago before I got it), but my biggest friend was PB Blaster. Rust comes right off

Import Convert

I should have mentioned that PB Blaster is THE BEST product you could possibly use on those studs! To compare I put PB on the bottom studs and Liquid Wrench on the top. The bottom studs broke loose with a regular box wrench. I had to put a breaker on the top ones!

pomanferrari

iTrader: (1)

VW Passats and Audis use an electric pump for the heater core. The electric pump activates after engine shut off to continue circulating the coolant through the system. I've been meaning to try this with the FD line (for the last 5 years) but never got around to tracking a pump from a junk yard down. The pump is an inline electric pump. Set a timer using a 555 chip to run this pump for 5 minutes and it would cool the whole engine/turbos down.