82 Turbo plenum question

[elk93001]

The 82 turbo used exhaust gases (as opposed to coolant on the earlier models )to warm up the plenum. I know that the exhaust gases flow in from the port near the EGR, but where does it exit? I have the parts manuals for 76-81 and see the diagrams for those, I am interested in whether the newer plenum could be used in an older engine.

Thanks,
Larry

 

[bill]

you could use the newer plenum on an older style engine if you also swap the intake manifold to in order to retain the egr func.and keep the carb plenum heated.you could just swap it out without the intake change if you don't want to have it heated,that's the only reason the exhaust gases flow though it anyways,and it was probabley easier than running coolant lines all over the place as the older ones did.but if you didn't want it heated you could just disconnect the coolant lines to the plenum and not change anything.Now to answer the first part of your question,the exhaust gases come though the front of the carb plenum though a metal pipe comming off the intake manifold(thats why you would have to change the intake also)and they dont exit anywere.that is untill the egr valve(which is on the rear of the plenium) opens to let the exhaust gases flow into the upper part of the carb plenium(though a port just below the carb) and recirculates back though the engine.see very simple.i have had both styles of turbo engines and prefer the 82/83 set up better.much cleaner looking and less places for coolant leaks.I will add that either way mantain some heat in the carb penium.i disconnected my coolant lines on mine once(thinking less heated air getting into the turbo sould run faster)but what happened was that it had terrible driveabilty from a dead stop,it would always hesitate,because without the heat the fuel couldn't vaporize fast enough to get into the engine and hence a bog.i drove it like that for months(in the summer mind you)and thought somthing was wrong with the carb,but there wasn't.as soon as i hooked the coolant lines up the hesitation went away and actually got better gas milage and seem to run faster now then with it disconnected.so much for the cooler plenium trick.I hope this helps and if you have any other questions just ask.

 

[bill]

I almost forgot,depending on what year engine you plan on useing ,if you change the intake you may have to change the heads also.if you have the coolant style carb plenium it would probabley be easier to keep it that way,there's know performance differance from one to the other anyways.

 

[b4black]

In this picture you can clearly see the pipe Bill is talking about:
http://home.flash.net/~rjgeorge/images/intake83.jpg

The EGR heated plenum is supposed to heat faster for better cold start driveability.


It is interesting to hear that the engine bogs when the coolant heated plenum is disconnected (even in the summer). I wonder if it could be "tuned" by only partially shutting off the coolant lines? A thermocouple would help. This wouldn't be possible with an EGR heated plenum.


For drag racing, blocking the coolant would (should, could) still work, since bog isn't an issue when power launching.

 

[bill]

I was also suprized it hesitated like it did,even during 80 to 90 degree days,I figured that it was plentey hot outside to make up the differance between that and the engine heat,thats why for a while i thought it was the carb.I tried differnt carbs to see if it would work better but was always the same result.thats when i decided to hook the coolant lines up and presto the hesitation was gone.I've heard to block off coolant flow partly for better performance and les KNOCK,Ijust decided to go one step further and totaley eliminate it.BAD IDEA.like you said racing it wasn't a problem so much but other than that forget it.but who knows,every car reacts differently,it may work for someone else.

 

[fc227]

I have a "83 " and a "80" if you need them.

 

[b4black]

Unhooking the THERMC air cleaner will cause the same bog.

Inlet air temp something that doesn't plauge the SFI cars because the have a temp sensor after the air cleaner. The ECM can compensate for cold air and therefore beneift from it.