Jump to content

Melted pistons


Recommended Posts

  • Replies 51
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Thats shit mate. Well done on melting forged internals though lol!..... I can't remember but don't the pistons work 1 and 4 at the same time and 2 and 3 at the same time? Not sure I would say its the map if it's just the two. Maybe more down to the timing or something? Not entirely clued up on engine builds... Always thought forged internals would cope with pretty much anything lol


Link to post
Share on other sites

It's excessive EGT's which have caused the failure of a component in this case, the AFR and knock levels are fairly irrelevent.

Upon removal of the head did you check the timing belt? If this has retarded slightly it would have caused the exhaust valve to open later, keeping excessive pressure and heat energy in the cylinder during a time when it shouldn't have been.

So much more to tuning a car than just AFR and knock levels, I think many people forget this. The safe running of an engine relies on many more parameters.

This is what I'm saying I have seen Garrett inconel wheels that have melted due to tuning if they can be melted am sure pistons can!

Link to post
Share on other sites

This makes me sad :( hope you fix her taggy, you need to get the money's worth out of what you put in, you'll just have to put in a bit more!

It's simply an unfortunate circumstance, there's noone to blame essentially, it could be a fault that occurred well after mapping/engine build, it's likely that its just coincidence that it happened a few weeks after, if something was wrong during the time of mapping, no doubt TD would have noticed. Anyone with half a brain cell that maps cars would know if it was running lean enough to cause this amount of damage, surely.

Link to post
Share on other sites

Ai i agree there wasnt anything wrong when it was on the rollers as it was all checked over, only problem is trying to diagnoise the cause, car had a full tank of fuel at the time, the injectors were plug and play 372cc lime green tops (out of an MR2 a drect swap) but they were reconditioned and looked in good condition.

I have always been keeping an eye on temps and it didnt even get above half on the guage at the time, also i was going in a straight line at 135mph so its happened when the engine was working it nuts off, so if it did run lean this would of been the time this could of happned.

Does anyone have any suggestions on whats caused the damage and is the most likely culprit? I am also running a Walbro pump in the tank.

I think two cylinders down is steering me away from injector failure as its unlikely two have gone at the same time, i hadnt thought about timing, is this what it looks like has happened?

This makes me sad :( hope you fix her taggy, you need to get the money's worth out of what you put in, you'll just have to put in a bit more!

It's simply an unfortunate circumstance, there's noone to blame essentially, it could be a fault that occurred well after mapping/engine build, it's likely that its just coincidence that it happened a few weeks after, if something was wrong during the time of mapping, no doubt TD would have noticed. Anyone with half a brain cell that maps cars would know if it was running lean enough to cause this amount of damage, surely.

Link to post
Share on other sites

What cr pistons are you running dude? Could it be to do with them being put in a 5e instead of a 4e? Also did you have a thicker headgasket? And at 135 mph it wouldn't take long for any engine with fuelling/ignition problems to die. It could still be fuelling but the electronic side not the fuel delivery To the rail. What is your distributor set to? As in how many degrees BTDC is it set to? Its fustrating not knowing the cause of the problem, but it would be an idea to try and solve that before doing 135mph again.

Link to post
Share on other sites

This is what I'm saying I have seen Garrett inconel wheels that have melted due to tuning if they can be melted am sure pistons can!

Ay mate I agree, anything can be smelted if it gets the right temperature with the correct amount of energy.

Ai i agree there wasnt anything wrong when it was on the rollers as it was all checked over, only problem is trying to diagnoise the cause, car had a full tank of fuel at the time, the injectors were plug and play 372cc lime green tops (out of an MR2 a drect swap) but they were reconditioned and looked in good condition.

I have always been keeping an eye on temps and it didnt even get above half on the guage at the time, also i was going in a straight line at 135mph so its happened when the engine was working it nuts off, so if it did run lean this would of been the time this could of happned.

Does anyone have any suggestions on whats caused the damage and is the most likely culprit? I am also running a Walbro pump in the tank.

I think two cylinders down is steering me away from injector failure as its unlikely two have gone at the same time, i hadnt thought about timing, is this what it looks like has happened?

I personally wouldn't say its ignition advance related, unless there was literally no timing in the map what so ever, but since TD have done many of these engines now I'm sure it wouldn't be that.

Before removing the fuel pump, bridge two ports (can't remember which) and this will run the fuel pump, remove the banjo fitting to the fuel rail and grab a measuring jug/bucket. Measure the fuel flow for 1 minute and see what flow rate you get. I have known quite a few walbro pumps to fail or start failing, and its a hard component to diagnose because during mapping if the desired AFR is not reached then the mapper just keeps increasing the duty cycle.

Was the timing belt loose? Had it skipped any teeth?

In the cylinder head are any valves sticky? Is there much carbon build up around the valves or the squish area?

Edited by AdamB
Link to post
Share on other sites

Isn't the 370cc injectors a bit too small for the HP that you wear running?



Online calculators would say something in the region of 440+cc for your case.



What was the duty cycle that you were running? Should be fairly close to 100%


Link to post
Share on other sites

I have known quite a few walbro pumps to fail or start failing, and its a hard component to diagnose because during mapping if the desired AFR is not reached then the mapper just keeps increasing the duty.

I have heard of quite a few horror stories about these walbro fuel pumps.

Best thing get a supra pupm in there :p

Link to post
Share on other sites

Ay mate I agree, anything can be smelted if it gets the right temperature with the correct amount of energy.

I personally wouldn't say its ignition advance related, unless there was literally no timing in the map what so ever, but since TD have done many of these engines now I'm sure it wouldn't be that.

That is the complete opposite of what would actually happen.

As for the injectors been the problem. That shouldn't be the case either.

We can check them for you should you require.

If it was the fuel pump, I wouldn't expect to see those pistons damaged in the way. Again we could test the pump for you on our rig. Its important to find the issue before proceeding to rebuild the engine IMO.

Link to post
Share on other sites

That is the complete opposite of what would actually happen.

As for the injectors been the problem. That shouldn't be the case either.

We can check them for you should you require.

If it was the fuel pump, I wouldn't expect to see those pistons damaged in the way. Again we could test the pump for you on our rig. Its important to find the issue before proceeding to rebuild the engine IMO.

Could you explain please Ricky?

A guy who races over on TGTT had near enough the same problem, lucky enough though he was running an EGT gauge and was netting near on 1000 deg C at 1.2bar boost pressure, with only 8 degress igntion advance, he then re-wrote that map using det cans and found out that it was the low ignition advance which was giving him such high EGT's.

Link to post
Share on other sites

Not good, not good at all, Problem seriously needs to be addressdd before you fix it though. I'd get the injectors out and remeber which came from where and get them flow/spray tested. Then as others have said, check over the belt for signs of damage/where it has slipped.


Link to post
Share on other sites

Still not 100% sure i am going to rebuild it, the problem i have now is trying to get two pistons. Wossner only have 1 spare available in stock, so i need to find another one. Does anyone know anyone who has an unmatched set from an engine that may have gone bang before??


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...