I put a Hypertech chip (160) in my 1990 350 TBI engine back in 1991.

Do you think I will have any problems changing the thermostat to 170 or 180?

Thanks

 

Your fans will not turn off when the temperature hits the "on" temperature, and because of the higher t-stat, you will never hit the "off" temperature.

Great time to get into eprom burning and start by making that modification. You can even use your existing Hypertech as your "test" eprom for erasing and reburning.

Just don't get too disappointed when you scope out your Hypertech eprom, and discover that other than the fans and possibly a little extra spark advance in the low-mid range of your rpm, it is basically the same as the stock GM memcal.

 

Thanks Glenn. It's in a truck, so no cooling fans to worry about.

My concern was if they made any changes that would cause detonation with the slightly higher operating temps.

What do you think?

 

Truthfully, that really depends on the correctness of your current mixture. When I went back to a 180* T-stat I was overly rich, which seemed to be triggering an "inaudible" knock retard (I have my own theory as why this was happening). The hotter T-stat (along with a lot of other changes) drastically reduced it.

When I owned a carbed vehicle, I found running cold T-stats to be a major problem; the mixture needs some heat to properly atomize in my experience. A TBI is similar in that it is a wet-intake also. I use to only think that only "dry intake" EFI systems should consider a colder T-stat. I am now of the belief that ALL engines should use a warmer t-stat based on the tighter tolerances inside the engine.

Just one guy's opinion.

 

You are not the only one that thinks 160 thermoststs are too cold. I have seen enough opinions from people that have some experience to make me want to switch to 180.

I don't know how correct my current mixture is, but I have just spent several hundred dollars on tune up parts and sensors, so everything should be close to spec except for the Hypertech chip.

Sounds like the chip is a joke. I recall someone telling me that the chip did not change a thing except under full throttle.

I guess it wont hurt anything, so I'll give it a try. If it detonates, I'll look for the stock chip or just put the 160 thermostat back in.

Thanks for your help.

 

Your friends are right. It does very little (and in your case not even the fans) and those changes are only at the WOT area of the tables. Part throttle, no differences. So (in a bad luck kind of way), you are lucky that it does very little.

BUT do give eprom burning a try, it really is not as hard you may thing.

Read this article https://www.thirdgen.org/newdesign/tech/promintro.shtml . It is probably the best place to start if you are half interested in burning your own eprom. The total cost (without a scan tool) is under $200.00.

Just from the money you'll save on fuel (and you will), it pays for itself quite quickly. And once you have the equipment, you can do virtually anything to your engine and make an appropriate eprom. Lastly, with a scan tool, you'll learn to read "what your engine" is saying and be able to isolate almost any problem with a sensor. Scan tools are not too effective in diagnosing a mechanical problem, though they can indicate that something is amiss.

 

I did ALOT of back to back testing.
The 190 was allows CONSISTANTLY faster.
The aftermarket clowns just love using flat head technology. The 160 in some calibrations get you about 6% richer. Which feels faster. When you optimize everything there is no lose of performance at 190. My GN is shall we say a good performer, and I run it at 205.
Oh, and parts last longer.
Remember little things like piston clearances, and bolt stretch vary with engine temp.. Too cold not engine tension, and too lose of clearances.
Note:
You do want to watch oil temps, also.

 

I'm sold. New thermostat tomorrow.

You know, it's amazing how much cr@p is being sold today. I am restoring an old suburban and want to up the torque a little.

I've been doing my homework and learned that if you don't see an independant dyno test or some honest timeslips, then it ain't happening.

I guess I got off cheap. So far, my only screw up is the hypertech chip.

It sure is nice to be able to get away from the advertisers and magazines for information.

Thanks guys.

 

The Hypertech chip isn't a total waste. You can use it as a "donor" for buring your own eprom.

Now buring your own eprom isn't hype. On a basically stock engine, your primarily after increased smoothness, driveability, and better gas mileage. If your engine and original eprom was nicely matched, you won't notice a lot of extra horsepower. But if it wasn't matched, then you will due to the better efficiency. I am noticing that on stock vehicles the stock GM memcal tends to be a bit "rich", so there is generally some HP to be found; just not the 35-50 HP that chip manufacturers would have you believe.

Where a good eprom really starts to show its stuff for HP, is when the engine has been modded.

 

I plan to make a few mods. Hope gain 30-50 torque between 2000-4000 rpm with no changes in reliability & driveability.

I have 130,000 on the motor. No leaks or smoke. Runs good. Compression is ok (155-165).

I don't see the cost/benefit of changing the internals. I'll wait till a rebuild is required and maybe put the Vortec crate in it.

Till then, I'm going with a major tune up, Doug Thorley 1 5/8 headers are in the mail w/SpinTech muffler and Hi Flow cat (all 3")single pipe.

I'm still thinking about a decent single plane intake manifold and will probably do it.

Still researching 1.6 roller rockers. Bang for the buck is the issue here.

That is all I'm gonna do for the next 50,000 miles. I think I can use most of this stuff when I repower.

I have no idea if this will require a new chip, but if it does, I'll have to learn how to do it or find someone that can do it for me.

 

The HP is the beginning.
hang on as the guys get brave with the DFCO IAC and other stuff.
Some chips allow a lean cruise.
I run 17.2:1 AFR in cruise. And this is a 231 turbo 6 with 55#/hr injectors so I can twist the boost to about 28 PSI, which is plenty quick enough for me.

With some tweaking I have, much better EGTs so it's an instant spooling.

There is just sooo much to play with