IROC5.7TPI

Thanks for the clarification Willie. I have been trying to tell people for years but it seems they hear others say its no good and try and convince me i'm doing something wrong.

All I have to say is come take a ride in my car... I'll show you how well it runs. And I live in MI and get heat enough to where I don't even need the fan running to feel it.

RdRacerZ28

160 Thermostat will not harm your ECM...geez. The way you say it makes it sound like it damages the ECM. Like the engine running cooler makes the computer go bad. TPIS gets them from Robertshaw. They are $10 with the gasket. I have a 160 stat in my 94 car.it runs @ 174-181 degrees all day long with no problems. IT goes into closed loop 14-25 seconds after start up. On TPI cars without a heated sesnor you may find a problem going into closed loop.

Willie

....On TPI cars without a heated sesnor you may find a problem going into closed loop.

Jim,

As I stated previously, the ECM goes closed loop when engine coolant temp reaches 104 deg F. I've owned 11 third gens of which nine were TPI's, two were carbed; most were 305's while others were 350's. I've installed either a 160 or 170 t-stat on all and all attain closed loop with absolutely no problems.

Also, I have never seen a Robert Shaw 170 t-stat at any local parts stores, only 160, 180 and 195. That doesn't mean they don't manufacture the 170, on that I've never seen it marketed that way. GM is the only distributor I know of that carries the 170.

Willie

RdRacerZ28

I was just venting a little. I hear all the mis-nomers all day at work from people and have to help people filter through info that is in-correct and help them find good info. If you live in a warm climate you can run a 160 without a problem typically. A 160 or 180 would be fine and if you drive your car in the winter, you may want to slap a 195 in there then go back when it gets warmer out. I know if I take my car out in the winter for whatever reason, I don't have much heat because of the 160 stat. Heat for yourself is one thing but you also need to make sure you can keep heat in the engine. I didn't want to seem like a *****, but it just sounded like someone was telling someone that a 160 stat would make thier ECU go bad.

RdRacerZ28

Robertshaw makes them for TPIS....I don't think you can buy one in a store other than the GM one.

Damon

Willie's right. Engine temp has little to do with when the ECM drops into closed loop. It's mainly when the O2 SENSOR REACHES OPERATING TEMP. The ECM determinies this by counting how many times it flips over and under 450 mv (and maybe some other stuff, but that's the main thing).

I have heard elsewhere that engine coolant temp cvan be as low as 68*F and still go into closed loop if the O2 and other systems are ready to rock.

My experience with HEATED O2 sensors on 3rd gens confirms this bigtime. I can get them into closed loop within 30 seconds of startup from dead cold if I start immediately driving them.

I'm not here to argue the exact coolant temp number since I don't have any data to absolutely prove my number- and it isn't relevant to this conversation. Just here to agree that a 160 stat will work just fine. Used them many times.

Combined with bypassing the TB coolant lines, rigging the fans for a lower cut-in temp and relocating the MAT (Manifold Air Temp) sensor from under the plenum (the "oven") to a cooler location in the air filter box can make a SEAT OF THE PANTS difference in hot-engine performance on a TPI motor, as well as more consistent performance at the strip, street or anythwere the engine can "heat soak" in a hot engine bay before a run.