Turbocar myths and half-truths

Myth #1  "20 pounds of boost! how often do you change headgaskets?"

Answer- almost never.

leaking or "blown" headgaskets are caused by one of three things in my experience.

1) normal wear and tear
2) poor installation
3) overheating/detonation

Myth #2  "turbo engine? they are throwaway motors after 100,000 miles"

Answer- Nonsense.

Almost any motor will last a long time with proper maintenance and handling, I have had several turbo Mopars with over 150,000 on the clock and one GLH-T that had over 190,000 with its original motor and turbo in it. (never rebuilt) My current daily driver has 135,000 miles on it and can run 12's pretty much at will.

Myth #3  "you need a catalytic converter for backpressure or you will hurt the motor"

Answer- More nonsense.

You need a C.C. on your car because your electronics cannot handle the extra exhaust flow and your boost will go higher then the factory "target".  Your engine will suffer no damage because this "backpressure" is no longer present.  As a matter of fact the first time you stuff your foot in it and the tires are smoking because your making another 20-30 h.p. you will be wondering why you waited so long!

Myth #4  "headbolts have to be thrown away every time you use them"

Answer- Maybe.

Mopar specifies that headbolts SHOULD be replaced if they have been used twice. I have found a simple way to test headbolts and its never failed me yet.  First step is to throw out any bolt that looks stretched or has some corrosion on it. Then you install the bolts using the procedure in the factory service manual, then stop before the last step.

The last step is to turn the bolt a 1/4 turn from the last torque reading (65 ft/lbs for an 11mm headbolt) set your torque wrench to 100 ft/lbs and do your 1/4 turn. If the bolt is good you should have no problem getting that reading before you hit the 1/4 mark, if a bolt is bad it won't come up to the 100 ft/lb mark. Just replace that one and continue on to the rest of the bolts.. I mention this little test of mine because I know most FWD Mopar racers have a bucket of bolts lying around from engines that have been striped, so spares 9 times out of 10 usually aren't a problem...

Myth #5  "if you pull the head off a 2.2 it must be planed"

Answer- No.

Myth #6  "52 mm on a 89 1 piece intake? don't waste your time, it doesn't flow well"

Answer- Not true.

89-94 1 piece turbo intakes flow just as well as their 86-87 2 piece relatives.

Myth #7  "a mitsu turbo wont make more power at 18 psi vs 15 psi, its all heat expansion"

Answer- False.

(Gus's phone conversation with a mitsu engineer) He explained to the guy you turned up the boost and the car went faster, you turned it up more and the car went faster still. The guy said it was impossible the air was all heat expansion.  Proof is in the timeslip is all I have to say...

Myth #8  "lean is mean"  (to infer your car will go faster being lean)

Answer- Dangerously false.

Only if you wish to smoke a few pistons... lets put it this way, to some extent the fuel ratio for max power on our engines is 12 to 1 which works out to about 1575 degrees F.  You have some leeway of course on each side of that number which to play, cooler (richer) at most you risk losing 10% of your h.p. if your running very rich, to far on the other side however and you risk melting a piston at 1700-1800 degrees.  In my own k-car which has an EGT gauge the car runs the same MPH and ET at 1575 as it does at 1700 (the highest I have risked going) so in this case the only thing "mean" is when your piston melts from being "lean".  its a catchy phrase but not true.

Myth #9  "you cannot mix synthetic and normal motor oil"

Answer- False!

Hell they are selling blends of the stuff at the stores now.

Myth #10  "smooth upper hoses are needed to make horsepower with the stock intercooler"

Answer- False.

Disproved this on two occasions with two different cars on back to back passes, no gains of any kind were noted.  Trust me, that stock intercooler hurts your flow far more then the ribbed upper intercooler hose ever will.

Myths sent in by readers...

Myth #11  ".5  voltage at the O2 sensor is the optimum for max power"

Answer- False.

  "A well-respected guy on my DSM mailing list stated that turbo motors make the most power at .5V on the O2 sensor! He obviously confused "stoichiometric" (most efficient A/F ratio) with maximum power production. But I cringe to think of what's happening to the poor souls that try to run 25 psi at .5V."

See #8  "lean is mean"

Myth #12  "you can't intercool a log manifold T1, you have to switch to a later manifold"

Answer- False.

You CAN intercool a car using the early (1984-1987) Turbo I intake but the boost starts "stacking" up in the intake after 12 psi of boost. This isn't a problem with the later model intake manifolds. The early intakes are also hampered by a smaller throttle body as well  (42 mm vs 46 or 52 mm) It can be done but power output isn't nearly as high as a car with the later model intake.

Myth #13 & 14  "S60 top end with a T1 bottom end?  And a 525?  I *guarantee* you won't get halfway down the track without blowing it up." and "If he was running 20 psi of boost with those parts (85 Turbo I shortblock) he would blow the dipstick out clean through the hood"  Quotes uttered by auto engineer who shall remain nameless.

Answer- Perhaps.

The Turbo I internals "in some cases" may not be as strong as their Turbo II relatives but all are more then strong enough to make more then one pass down a dragstrip at high hp levels! The first intercooled motor in my 86 Daytona (285hp!) ran at 20 psi of boost for years and racked up over 50,000 miles on it before it suffered a failure of any sort. (The 525 is kinda fragile at those hp levels, it is only rated for 175 ft/lbs of torque)

Myth # 15  "100,000 miles on a turbo means the turbo is fried, regardless of maintenance history."

Answer- Nonsense.  See #2.

Myth # 16  "If you run the turbo past it's factory boost setting, it is called overspinning the turbo, and you will destroy the turbo."

Answer- True and False.

It is called overspinning a turbo when your operating a turbo outside it optimum map range, this much is true. But if your turbo has been built correctly and you follow proper maintenance along with common sense (letting the engine cool off before shutting down the car after hammering on it) your turbo will have a long and happy life.

My car? 135,000 miles on the motor and turbo.  Stock boost? 12 psi.  What do I run it at?  25-30 psi.

Myth # 17  "Big intercoolers cause lag"

Answer- False!

I'm guilty of this one, you would think the extra mass of air and the long hose runs would cause lag no? Well it doesn't, as a matter of fact in the K-car after I installed my "double size intercooler" the throttle response and spool up was NOTICEABLY better.
Myth # 18 "Turbos don't glow.  If your turbo glows, you have more problems than you know!"
Answer- True and False.
It's quite normal for your turbocharger to glow after "spirited driving" after all your exhaust flow is as high as 1500 degrees! The more power you make the more your turbo is likely to glow a bit after hammering on the car...
However it is possible that your cam timing ot distributor timing is off and that would cause you turbo to glow A LOT!  I have seen one car where the cam timing was off far enough where the turbo got so hot that pieces of iron were flaking off the housing!  If everything is in order moderate amounts of "glow" is normal....
And remember to let your car "idle down" a few minutes after hard driving, your turbo will live a lot longer....

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