Test session at the Las Vegas “Strip”
I use a low boost level of 19 psi and run a few shakedown runs. End up running 12.4 @ 113 MPH, by just grandma shifting her
down the track. The car already feels better than my 2G with a 20G @ 23 psi.
I bump up the pressure to 25 psi with Unocal 76
racing fuel. 112 leaded fuel in the tank and the timing curve is in the 22-24 degree range. My best runs are 11.7 @ 121 MPH
Extremely consistant runs. With the 5750 RPM launch
rev limiter, the car get 1.7s 60fts consistently. Back to back to back 11s.
The temperature increases here in the desert.
The times are the same, but I seem to have developed a coolant problem. I notice the temperature above 220 after the 6th
run of the night. The coolant has filled the overflow, so I just unbolt it and pour it back into the radiator. I still am
able to pull the 11 second quarter with track temperatures at 100 degrees
I have to pour the coolant back out of the overflow
and into the radiator after every run. I’ve been searching the internet for causes, and it seems to be a blown head
gasket. I can’t see how I have a blown head gasket when the car is so strong. 25 psi down the track and I still get
120 MPH trap speeds. There is absolutely no smoke coming from the tailpipe.
Same coolant problems. I purchased a new Mitsubishi
radiator cap to see if that would prevent the coolant from escaping out the overflow. I didn’t work. This year seems
to be an extreme Summer here in Vegas. Avg. temp this month is around 113F. The overflow would fill up and the radiator would
only be half full of coolant. Still no smoke.
I end up performing a compression test. 183-182-185-182psi This is an absolutely strong engine
according to the numbers. Head Gasket problem?? Yeah right. But why am I pushing coolant?
This is getting bad. After an 8 mile drive to
work, with no boost, I am filling up the overflow. I even installed an additional overflow bottle to hold extra coolant. Boost
pressure is some how getting in the cooling system and pushing all this coolant out. After every drive, I have to get out
and slowly open the radiator cap to release the excess pressure out. If I don’t do this, the coolant in both overflows
will not siphon back to the motor.
Even after all these problems, I still take it
to the track. I can’t seem to bust out any more 11’s. Best run of the night is 12.2 @ 116MPH, but I contribute
the slowness to the hot temperatures.
Now the pushing coolant problem is getting so
bad, I have to carry extra water with me just to drive the car just a few miles. I fill BOTH overflows in a few miles without
even getting on it. I must be spilling coolant all over the street when I drive. How can a head gasket do this without throw
white smoke out the exhaust? Why are my compression numbers still good?
The trip to the track was one to remember. I emptied
both overflows back into the radiator before getting to the line. Coolant temps were 150 degrees. First pass was 12.6 @ 113
MPH and it was misfiring throughout the run. I check the overflows and BOTH are full after just 13 seconds of throttle! Over
a gallon and a half of water was pumped out the radiator in less than 13 seconds! That’s just about how fast a gas station
pump is! I can’t imaging what it must have looked like in the engine compartment, having coolant escape that quickly.
Now the car is misfiring even at idle. I call
it a night and I hope I can even get this car home without a tow truck. My house is 25 miles away from the track. I end up
pulling over every 3 miles to refill the coolant. I’m just dumping it on the highway when the overflows fill up.
The next morning I check the motor out to find
that the oil dip stick level is twice as high as normal. 4 quarts or oil and probably another 4 quarts of coolant. I’ve
been putting off the inevitable and now I know I must pull the head and look at this head gasket..
With the help of JR from, HorsePower House of
Las Vegas, we pull the head and find coolant in cylinder #4. We figure the gasket must have taken a dump that side of the
block. The surface of the block checked out well, but the head was warped. We sent out the block for resurfacing and I ended
up picking up a new GT35R and a new T3 manifold for new power.
After reassembly, we drove the car around, and
the new turbo felt great. All 4 tires lit up when you went WOT in 2nd gear. It's a pretty wild beast and extremely
torquey. After we got it back in the shop, I noticed a coolant leak. I figured that we needed to tighten down a hose clamp
we missed, but it was coming from the overflow AGAIN! It started to misfire also once the coolant temperature gets to operating
levels. We have to pull this head off again to find the real problem. The head gasket was never the problem. I noticed the
crack on #4 once we got the head off for the second time.
Check the “Cracked Block” link for
more info and pics.
I hand deliver the short block to Road Race Engineering
and a brand new short-block is on order for me to receive by January 2006. Rob at Road Race Service has never seen a 4G63,4
motor crack like this. It’s a waiting game again. This car has been down for more than 4 months now.