graebz28

iTrader: (5)

I'm running a 180 now, but read about how a TBI likes heat for fuel atomization. Since I am still in open loop tuning mode right now, I want to know if going back to 195 would be beneficial before getting into major AE,PE and closed loop tuning. Please respond if you are running heavily modded and tuned TBI. Getting more hp on a stock ride w/o tuning may work by fooling the ecm. What is the stock ecm temp that a ECM goes into closed loop again??

vjo90RS8

iTrader: (1)

doesn't matter too much. The stat will open sooner but the engine will still heat up until the fans kick on during city driving. If you are driving on the freeway in cooler weather than the coolant temp might stay around 200*. remember, 180* is where the stat starts to open, but it won't be fully open until 5-15* hotter.

RBob

iTrader: (1)

Closed loop enable varies a bit, but in general is around 120*F. For an engine with aluminum heads, street driven, I prefer a 195 thermostat. If I could get a 185 or 190 I'd give those a try.

The 180 tends to be too cold, while the 195 tends to be on the warm side.

It also helps to have some heat in the intake manifold plenum. Currently with the Performer RPM I run coolant through the crossover passage. Did the same with the Torquer manifold. Helps with driveability. Use 3/8" hose for feed & return, so there isn't a lot of heat.

RBob.

graebz28

iTrader: (5)

Thanks for the input.

RBob,

On my 406 I tapped lines into the head for cooling per Stewart's Water Pumps instructions. Would I do something similar to this, but to the manifold intake runners? I am running a GMPP one which I think already has coolant passages; can I do this on a GMPP? I do a search later to see if you have pics online.

Dang it was a pain to find a 190, but I think the one on this page should work.

http://www.racepages.com/products/?D...94965395&Nty=1

I'll see if advanced auto carries the part number.

RBOB, One more ? since I go ya here. Typically, you have said that fast burn heads or vortecs require less timing. Can you elaborate? Does that means they require less ADVANCE or less total timing. I am having hard time interpreting what feels better when varying sa-idle from 15 to 23 degrees.

RBob

iTrader: (1)

Most likely a GMPP TBI intake has a full water jacket under the runners and around the plenum. I know that the stock L03 and L05 TBI intakes are set up this way.

The exhaust crossover is more of a carb style intake feature. The '113 heads don't have exhaust at these ports. Just a block off cast in. So it was easy to drill/tap the manifold crossover for water and plumb it in.

Thanks for the tip on the 190 thermostat. At first I couldn't believe the price. Then I noticed the stainless steel and app, makes sense.

Spark timing at idle isn't as critical as when at load. I would try 21 - 22 degrees at idle an see how it works out. Biggest is to find a SA value that allows for a smooth transition to open throttle. Such as when pulling out from a stop.

For the e-tec heads I would start with some Vortec head spark values. Not having tuned an engine with e-tecs I can't really say what they will want.

RBob.