Slant 6 Turbo needs tuned.

[finnman1]

Finnnaally got her going and all the leaks taken care of. Only problem now is she overheats and it acts a little funny under boost when i romp on it. It makes a ppffff sound and acts as if it stops pulling. It will still build boost (had it up to 8 lbs tonite but it was making that sound so i let off) Didn't know if anybody had experience with this. This is all new to me. The turbo a .42 garrett and i've seen it on a diff slant before so i know it's not necessarily too small. Any of you guys know what this is an indication of?

[tkelly27]

sounds like a boost leak to me. I had a split hose one time that would only open under a certain amount of boost. To test it I made a plug from PVC pipe and filled it up with an air compressor. Does it have the stock rad? Might be overheating from the extra power you are putting into it. Also, when you get on the boost, it's a big rush of power and can be difficult for the cooling system to remove it, so unless it's going into the red on your gauge, it might be normal.

[finnman1]

well, i don't think its a boost leak because all the lines are good, and the sound is loud enough and defined enough that i think it's something bigger maybe the turbo fluttering or the engine. Man, i really dont know what it is. its something big going on though. i guess you could compare the sound to a blowoff valve or something like that. but it's a constant ppffppffppffppppffppff.
as for the cooling system, i think you're right about needing a bigger radiator. my old man had a 318 in a slant6 truck and it overheated a little. but w/ this thing, i'm afraid to let it just get hot and grenade.
oh, and when it makes the noise, it stops pulling, it doesnt stutter or kill, you can feel the seat of the pants feeling diminish.

[john1320]

Do u use a bov? I only ask because there is no where for the pressure to go, when the carb blades close.

[wallace]

Did you leak test your cold side piping? I just made a rig to test mine and found several bad leaks at welds I wouldn't have guessed would leak. I'm betting it's a leak too.

[mpgmike]

There is another problem that fits your description...too small of exhaust pipe. You should be running 2.5" minimum, and 3" preferred. If you have the stock exhaust pipe still under the car then there is your problem (I know, I did that on a L-6 turbo conversion back in '98).

Mike
www.PowreHaus.com

[15w/ashelby]

Timing off?

[finnman1]

timing's dead on. using a msd boost timing master to retard. the waste pipe is about a foot long w/ a collector insert to deaden the sound a bit. basically a open exhaust. i used a piece of flex pipe for the hot side into the turbo. that's probably leaking. those arent air tight are they? i wonder if header wrap would seal it off. isnt that like an ace bandage for a sprained ankle material?

[finnman1]

also.. its overheating badly so i wonder if i was to pinch the coolant feed hose a bit to restrict flow to the turbo to prohibit a bit of that hot turbo coolant from getting into the radiator so it stops overheating. BAD IDEA?? the turbo is oiled and the coolant just cools it right? 1/2 the coolant flow to the turbo wouldnt be That bad right guys??

[tkelly27]

"i used a piece of flex pipe for the hot side into the turbo." Lol, that would have been good to know before hand. You need a bigger radiator and a solid pipe. The hissing sound you are hearing is the exhaust leaking out of the hot side. You feel it stop pulling because it's basically acting like a wastegate, only it's not controlled.