Turbo Gen 1 plugs hit 2 pistons...

[06.5 racing]

Looking for answers to why... We are running a turbo gen 1 (new build) in a race car. Stock crank, rods, pistons etc. Only about 7-9 lbs of boost. Car ran fine in the first race, but started running very rough and stopped during the 2nd race. Turns out #3 and #4 plugs had the gap closed?!? It seems to me that if the piston/plug gap at TDC was insufficient, for whatever reason, that it would have presented itself immediately. The only thing that was different (as far as I can tell) was that it was running hotter on the second day (water temp indicated in the 210-220 range). Our intercooler (I call it an "interheater" ;-) doesn't seem to be working because the data showed the intake charge was 150... ) Could the extra heat have expanded the internals enough to make that much of a difference? What is the clearance between them normally? Does anyone have any ideas? Thanks in advance...
Scott

 

[202mphbusa]

maybe hurt a couple pistons and the pieces that came off hit spark plug electrode

 

[LC4CARL]

Radical!

 

[LC4CARL]

Can you scope the cylinders to check for witness marks in the carbon on the pistons?

 

[06.5 racing]

Radical!

We race against Radicals, but it's a Stohr.

 

[06.5 racing]

Can you scope the cylinders to check for witness marks in the carbon on the pistons?

Unfortunately, our scope won't fit in the tiny plug holes...

 

[LC4CARL]

We race against Radicals, but it's a Stohr.

Super cool! I used to do tech at the local track. Some these cars are insane!

 

[LC4CARL]

This is going to get over my head very quickly. But what plugs are you running? Do the porcelains read hot? Any indication of pre ignition?

What is odd to me is that two holes failed. I could see a random mechanical event in one hole, but not two.

IC is "air to air?"

 

[sixpack577]

Was it dyno-tuned or data-logged and tuned?
What is the air/fuel ratio?
If 2 cyclinders got hot enought to close and weld shut .035-.050"(roughly) spark plug gaps, then either the tune is way too lean, or you have air leaking into 2 cylinders.

 

[michael parris heuberger]

Ok

Was it dyno-tuned or data-logged and tuned?
What is the air/fuel ratio?
If 2 cyclinders got hot enought to close and weld shut .035-.050"(roughly) spark plug gaps, then either the tune is way too lean, or you have air leaking into 2 cylinders.

Hi. You said stock rods. Maybe rod stretch? How many RPM's you turn? The one I am building will turn 13500 RPM I use a Marine custom crank, custom Carrillo rods 13500 to over run of 14500 . The ae not off the shelf. I think they were $1800.00 to $2200.00 and custom J &É pistons. This motor should make 800 to 1,000 HP. We are at Loring LSR race with the B bike our supercharged busa.

 

[06.5 racing]

Was it dyno-tuned or data-logged and tuned?
What is the air/fuel ratio?
If 2 cyclinders got hot enought to close and weld shut .035-.050"(roughly) spark plug gaps, then either the tune is way too lean, or you have air leaking into 2 cylinders.

Data logged and tuned by a turbo Busa expert. The gap didn't "weld" but looks like it was hit by the piston. Our last motor ran too lean and burned the pistons well before the gap was welded closed...

 

[06.5 racing]

Ok

Hi. You said stock rods. Maybe rod stretch? How many RPM's you turn? The one I am building will turn 13500 RPM I use a Marine custom crank, custom Carrillo rods 13500 to over run of 14500 . The ae not off the shelf. I think they were $1800.00 to $2200.00 and custom J &É pistons. This motor should make 800 to 1,000 HP. We are at Loring LSR race with the B bike our supercharged busa.

View attachment 1702764

View attachment 1702765

 

[06.5 racing]

I didn't run much over 9000, since the power seemed to be falling off. The AFR was set around 12:1. The data logging wasn't working well, but I had an alert if it went above 12 and it didn't under load.

 

[sportbikeryder]

I would guess you cooked the engine. It didnt just hit the plug, foreign matter or material came loose inside the chamber and hit it, or you melted it.

Runing a stock engine with 7-9lbs of boost will likley cook it, especially when used in a car application.

Head can be left alone, with stronger springs added

If using stock pistons and rods, at least a thicker base spacer to lower the compression is needed (2mm/.080 is common)

I would put rods and an actual turbo piston in it, along with the valve springs and head studs rather than running stock parts.

I would also at least add a workig logger to be able to monitor the AFR and RPM on the engine while running it. If it is an OEM ecu, I can't imagine the fueling is correct for part throttle an being on and off the throttle often as one would see on a road course.

Not pulling above 9000RPM is a big red flag. Tq peak on that should be about 9800 RPM and power will pull through at least high 10K RPM's.

 

[06.5 racing]

I would guess you cooked the engine. It didnt just hit the plug, foreign matter or material came loose inside the chamber and hit it, or you melted it.

Runing a stock engine with 7-9lbs of boost will likley cook it, especially when used in a car application.

Head can be left alone, with stronger springs added

If using stock pistons and rods, at least a thicker base spacer to lower the compression is needed (2mm/.080 is common)

I would put rods and an actual turbo piston in it, along with the valve springs and head studs rather than running stock parts.

I would also at least add a workig logger to be able to monitor the AFR and RPM on the engine while running it. If it is an OEM ecu, I can't imagine the fueling is correct for part throttle an being on and off the throttle often as one would see on a road course.

Not pulling above 9000RPM is a big red flag. Tq peak on that should be about 9800 RPM and power will pull through at least high 10K RPM's.

We are logging the data through a Holley HP ECU to our AiM system. I'm not sure how much the power was decreasing over 9000, I was being conservative with a new motor and learning a new track and it felt like the next gear was pulling just as well. I never got to redline in 6th.

 

[202mphbusa]

Bearing spin allowing piston to move .055 higher? I think shells are that off memory

 

[sportbikeryder]

We are logging the data through a Holley HP ECU to our AiM system. I'm not sure how much the power was decreasing over 9000, I was being conservative with a new motor and learning a new track and it felt like the next gear was pulling just as well. I never got to redline in 6th.

You may want to look at fuel pressure. If you dont have a sensor and have an available input on the Holley, perhaps add one. You may be uncovering your fuel pickup in turns, causing fuel to be interrupted.