I have heard that cooler thermostats can actually cause the ECM to take timing away? Is this true? Would I be better with the stock t-stat in? I thought cooler thermostats meant less detonation?

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91 Formula
305 TPI 5speed
1LE/G92/WS6

Paxton SN92 polished kit, SLP airfoil, ported/polished plenum, March pulleys, Crane AFPR(43psi),Crane Gold 1.6rrs,MSD coil,MSD6AL (5200rpm limit),Holley 9mm wires,Ac delco R43ts plugs,stock chip,Ford SVO 24# injectors,Bosch O2sensor,SLP 1 5/8" headers,SLP catback,shortened shifter,3:73s w/Auburn posi,170* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.

 

I haven't seen anything in some code hacks or chip programs that indicate that a cooler 'stat would cause the ECM to take out any more timing than it would with a stock 'stat when knock occurs. Generally, a cooler 'stat will help prevent detonation since there's less of a chance of any hot spots on a cylinder head from causing it since the head is cooler overall. Obviously, if the engine's running too cold and you're getting piston slap (like what happens with forged pistons on cold start-up), then the engine will see this as knock and dial back the timing, but that's before the engine has warmed up.

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Greg Westphal
'87 IROC 305TPI/A4

 

I have found a cold engine or a engine not fully warmed up more prone to knock retard.

If by pulling away timing you are referring to the "octane spark retard" which pulls away timing when knock is registered when high loads are on the engine, yes. That retard is not temperatrue dependent though. It occurs whenever knock of more than 4* is detected with a load of 70 kpa or more. That routine will pull up to 4*s away and is extremely slow to recover. You basically have to turn the engine off to recover the stolen spark advance.

 

That isn't what I seen in actual tuning when optimized for either operating temps.. This universal law of lower operating temps goes back to Flat head Ford Days, and just been repeated to where it's fact, for some. If the 160 operatin temp was true, why does NASCAR, CART, IRL, run at 210dF?.
For the average street car there is more damage done with a 160 then a 190.
Hyperstick, and others want a 160 for the extra enrichement, ie to lazy to tamper with the fuel tables.
In back to back testing with optimized cals, I found no difference in operating temps, but if you think your way though piston clearances, head bolt tensions, the 190 is best.
BTW, the GNs are supposedly really sensitive to this, and I run mine at 210dF, and it does just fine. At 25 PSI I can run 3d more timing then best performance and not hit the K/S

 

This may be true as far as efficiency goes, but not as far as max power goes....Ask any drag racer....cooler engines produce more power. My tpi engine is VERY sensitive to heat. I can slow down by as much as .3 between rounds if I dont have enough cool down time. I have found that the motor performs best when at or below 160*, and slows considerably at 170 or above.

Also: NASCAR and other circle track racers have fuel efficiency to contend with that a drag racer would not consider.

[This message has been edited by Desert86Roc (edited March 14, 2001).]

 

But did you try actually optimizing for the difference in temps?.
If the calibration is set for best running at 160 then of course it will run best there.
Change the timing and fuel for actually running at 180 and see what happens.
If you want to beat a point to death then Running no coolant like in Top Fuel can have it's advantages. But billet heads aren't vary practical on the street.

Heat soaking is very different from operating temps...

 

How does a top fuel cool down grumpy? Is the extra amout of fuel the cooler for the engine?