Hello everyone, thanks for reading... Here is a run-down of what is going on with a friends car:

GSR longblock, CTR pistons, CTR/ITR cams, boltons. Conservative tune, 93 octane.

So far, this motor has lost two pistons in cylinder #3, in a row. While I don't have any pictures of the piston nor have I seen any yet, the owner of the car said the piston was "deformed" looking. I am guessing it melted from heat.

Someone has told the owner of the car that he is losing motors due to the CTR cams not being aggressive enough for the CTR pistons, and that they are causing the issue. In MY opinion, if he is losing pistons on the same cylinder each time, and the other 3 are fine... I suspect an injector or wiring issue on that one cylinder.

What do you guys think?

- Louis

 

What do the spark plugs look like?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Master of the Universe &raquo;</TD></TR><TR><TD CLASS="quote">What do the spark plugs look like?</TD></TR></TABLE>

Not sure, just left a message with the cars owner to find out.

MOTU, have you ever heard of motors blowing because the cams weren't aggressive enough for the compression?

 

#3 is usually the hottest. ive had an extremely similar setup last quite a while(c5 motor/head, mugen hg, ctr cams, ctr pistons) but not without spark knock(hot days, low rpm high load situations). so its possible it could be a combination of the cr/cams/and possibly a weak injector

 

Just sounds like to much CR for the gas. Piston #3 usually goes first.

 

High compression on pump gas can mean death for motors. We usually have to pull a bunch of timing on setups like that. You can check EGT's and A/F for the cylinder that is letting go to see if there is a problem on that cylinder alone, but number 3 is usually the first to go when A/F's or ignition timing are a problem.

 

Okay, so the cams should have little to nothing to do with the issue. It's most likely related more to the compression and pump.

Would using a second (or thicker) headgasket put him into a much safer comp. ratio?

 

1. Reduce CR with thicker head gasket.

2. Also what ECU program is being used? Need to use a custom timing map that has toned down timing in part throttle as well as lower WOT timing.

3. If the pistons are hurt chances are other parts are hurt as well such as cylinder, valves etc.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Master of the Universe &raquo;</TD></TR><TR><TD CLASS="quote">1. Reduce CR with thicker head gasket.

2. Also what ECU program is being used? Need to use a custom timing map that has toned down timing in part throttle as well as lower WOT timing.

3. If the pistons are hurt chances are other parts are hurt as well such as cylinder, valves etc.</TD></TR></TABLE>

1. Thick headgasket will be suggested to him.
2. Hondata S100
3. Everything else has looked fine. But I will have him have it all inspected.

Thanks much, guys.

 

why not just go with some p30's instead of the thicker headgasket to bandaid the pct piston design

 

You need a bigger cam and some overlap to reduce vaccuum at low rpms

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mar778c &raquo;</TD></TR><TR><TD CLASS="quote">You need a bigger cam and some overlap to reduce vaccuum at low rpms</TD></TR></TABLE>

What does that mean for this particular setup?

 

A cam with a larger primary and more overlap will lower vaccuum at lower rpms. This will lower the amount of air taken into the cylinder. Inturn, this will richen the fuel mixture and reduce the tendency to pre-ignite and lower combustion temps.

 

[QUOTE=b19coupe]High compression on pump gas can mean death for motors. We usually have to pull a bunch of timing on setups like that. You can check EGT's and A/F for the cylinder that is letting go to see if there is a problem on that cylinder alone, but number 3 is usually the first to go when A/F's or ignition timing are a problem.[/QUOTE

I understand fully the reasoning behind pump gas and high compresion = detonation but can you elaberate as to why cylinder 3 gets hottest first??

 

i did that a few months ago w/a a friends car.. it was detonating its *** off on the dyno so i told him to park it till he got bigger cams.. of course he didnt.. blew 3 pistons to **** [freak]ed hte rods, the bearings etc..

 

[QUOTE=b19coupe]High compression on pump gas can mean death for motors. We usually have to pull a bunch of timing on setups like that. You can check EGT's and A/F for the cylinder that is letting go to see if there is a problem on that cylinder alone, but number 3 is usually the first to go when A/F's or ignition timing are a problem.[/QUOTE

I understand fully the reasoning behind pump gas and high compresion = detonation but can you elaberate as to why cylinder 3 gets hottest first??

 

If your saying that Cams are not big enough for his compression, which should be around 12.9 give or take, Would this be the same for forged 12:1 pistons with gsr cams?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DarKStaR5 &raquo;</TD></TR><TR><TD CLASS="quote">If your saying that Cams are not big enough for his compression, which should be around 12.9 give or take, Would this be the same for forged 12:1 pistons with gsr cams?</TD></TR></TABLE>

It simply means that they will work at that compression level but larger cams would work even better.

In this particular case, high compression/aggressive timing and pump gas may be responsible for destroying this engine. Cams that have more "overlap" help reduce the effective compression ratio a little possibly making this engine run "better" and not detonate. This would be considered more of a band-aid approach though and the build/tune should really be re-thought.