MR is installed and looks great. I'll post pics later.

I have a new problem.

Here's the short story...ran my first 1/4 mile (13.19 @99 MPH). Checked the engine bay out and found oil blow out the side of the intake manifold. I drove it home 70 miles with the engine performance being fine. On the way home, my PCV valve popped (shot) off.

Fast forward....since I had to pull the TPI setup to fix the intake gasket, I decided to upgrade to the MR (thanks to all that gave me input on MR vs HSR vs SR). The shop doing the work got it all back together yesterday. When they started the car up, they saw alot of blow-by coming out of the same PCV port that shot off.

Investigation showed:
1) PCV port on left (drivers) side of enging
2) Oil in tail pipe on right (passenger) side
3) Plugs look a little dark, just a hint of oil on cylinders 5-8
4) Compression test (readings from memory, not exact)
#1....185 #2....85
#3....186 #4....70
#5....185 #6....80
#7....140 #8....120

At this point I had to leave so I don't know what they did next. We were talking about leak-down test, head problems, etc. One of the strange parts of this is that when the engine is running, you hear no miss or apparent problem with the motor.

So, we have an engine problem. Not sure exactly what it is yet. Any opinions?

I'm hoping for the best scenario....something simple. I'm sure it wont be.

 

Excessive blow by = crankcase pressure. Use a bore scope to look in the cylinders with the low compression, I suspect the cylinder walls are scored. Or pressurize the low reading cylinders with shop air & listen at the oil fill cap. Compare the sound of the excaping air to a good cylinder.

Its not terminal. It needs a bore job & new pistons/rings.

 

My car did this because I had detonation on my Hypereutectic pistons and I had cracked 3 pistons,

If you PVC popped off, my money is on broken rings or cracked pistons, or both,,,, sorry

 

IMHO, low compression and crankcase pressure sounds like bad rings or piston damage.

 

So, lets assume I've got a couple cracked pistons. What would have been the reason this happened? The motor only had about 20k miles on it. Custom built 13 years ago using only the best parts.

I'm not an engine expert, so please keep it at novice level.

 

Simply put, if an engine runs lean, pistons melt or break. Cast and hyper pistons shatter like glass, and forged melt. Do a leak down test.

 

I am wondering what caused a problem on only one bank.

 

I just had a dyno tune and optimized the A/F mix. As expected, the engine leans out with the TPI system around 4500 rpm.

So, following your comment, did the engine over rev during the 1/4 mile run.....creating a lean condition, which then caused the hyper pistons to crack? It seems like my engine shifts gears (700R4) at 6000 rpm. When I did the run, I just floored it and let it run through the gears automatically.

Prior to the run, I don't think I had a problem????? Or did I and didn't know it?

 

Hard to say. Lots of reasons for a lean condition. Air leak, bad injector(s), bad tank of gas, mass air sensor failure, etc, etc. Don't panic yet, but the oil blowing out strongly suggests the need for a leakdown test.

 

I finally had a cup of coffee, and reread your opening post. Based on the compression tests, motor is hurt. Oil out the pipes confirms it. Do not spend any more money diagnosing it. Pull it out for the rebuild.

 

Thanks Pete. I'm sure your right about the rebuild. I'm headed for a bloody mary, maybe a double!

I'm just a little frustrated with my resto-mod C2. Since I bought it in January, I've now had to replace my transmission, and now the engine blows!

I bought the resto-mod style C2 with hopes of having a more reliable hot rod. I sure haven't driven it hard. One 600 mile trip and the trany goes, one 1/4 mile run and the engine goes. All this happens after only 20k miles since the restoration (completed in 1997)

With these kinds of failures, the previous owner must have abused the #*it out of the car. You would never know it by looking at it. Very clean and appeared to be well maintained.

 

If you are lucky, detonation took out the rings, not the pistons.
I have never been very lucky though
Forum member ski_dwn_it was disappointed with his performance. Upon disassembly, the rings fell apart in his hands.

 

• 2008-09-02: Tuned
  "I just had a dyno tune and optimized the A/F mix. As expected, the
  engine leans out with the TPI system around 4500 rpm."
  .
• 2008-09-10: First 1/4 mi run
  "I shut her down after only one run because I saw some smoke and
  a little oil coming out around the back of the intake. It seems like my
  engine shifts gears (700R4) at 6000 rpm. When I did the run, I just
  floored it and let it run through the gears automatically. I drove it home
  70 miles with the engine performance being fine. On the way home,
  my PCV valve popped (shot) off.
  .
• 2008-09-26: MR installed while engine apart to replace intake gaskets.
  "When they started the car up, they saw alot of blow-by coming out
  of the same PCV port that shot off."
  .
• "the previous owner must have abused the car. You would never know
  it by looking at it. Very clean and appeared to be well maintained."

.

 

Suggestions needed.

If I'm doing a complete rebuild (assuming I have ring, piston & cyl damage), should I start with a new short block or rework what I have (parts & labor)?

If Short Block, which one
1) ZZ4 350 short block
2) 350 short block
3) 383 short block

It's matched to a 700R4 trany & 3.54 rear gears.

My car is for fun only. I don't race it, except for that once in a while opportunity (1 time and I blew the engine). I like the "seat in the pants" fun these cars give us.

Need your opinions, and please no "do what you want" comments.

 

383
10 t0 1 compression (assuming aluminum heads)
218 @.050 cam
2600 stall converter ( 9.5 incher)

 

Pete, I would try to use all of my existing components with the short block.

Cam: LSA 112, Duration @.050 224 intake, 230 exhaust
Ported heads, 2.02 intake & 1.60 exhaust
1.6 crane rockers
TPIS MR

I think my stall converter is a 2600 or 3000...can't remember.

Those components in either 383 or ZZ4 would work nice. Should I spend the extra $1k for the 383?

 

I would spend it. Your cam will work well with the miniram. One of the best things I have done to my ride was a 383.

 

383.