Great Head Debate!!!!!!

[Xtrempickup]

Here I go starting a debate again. Here's a good one i think at least. I hear about ppl burning up pistons all the time. A lot i hear are on the later yr cars and I'm making this to see what head casting experiened the most number of detonated/burnt up pistons. obviously there are at least 3 stardard 8 valve Turbo castings and a couple 16V i'm looking to see votes on. i'm gonna list them, if you burnt pistons in any of them, you know what to vote for.

[cordes]

It's the higher A:F ratios being burnt in the combustion chamber not the heads.

[Xtrempickup]

not totally correct, thats just one factor, i'm looking to see which head over all whether it had burnt pistons because of a/f whether, stock or modded, whatever. let the thread play out. humour me

[zin]

1st off, I gotta say I'm a little disillusioned, this thread is not what I thought it would be.

That said, I see what you are going for, trying to see if there is a pattern regarding style of head and carnage. Sure the water will be muddied by all the other factors, timing, lack of fuel, etc. But it might just show which head is the most forgiving of tuning errors and which one is not. That's what I assume (now) this thread's goal to be.

[moparzrule]

I've broken pistons with both the 287 and 782 head, so not sure what to vote for. I'm thinking the 782 head because when I blew up a piston with the 287, it took a lot more ''effort''.
Right now I run 1700 degree EGT's with a G head, been doing my own cal's and timing is maxxed out and fuel is good. Been running it that way for a couple thousand miles with no piston issues, stock mahle pistons.

[Xtrempickup]

Yes, which head is more forgiving or less forgiving and that way, maybe somebody can look to see where they can start their build considering what they have.

[moparzrule]

Just thought of something else though, with the 16V heads, if you use them on 2.2 pistons it becomes and interference engine. In that case, snap a timing belt and you'll have a lot of carnage be it pistons, valves, guides, the whole head, cylinder wall, basically the potential to trash the entire engine.

[Xtrempickup]

i think i geared the choosing so you can choose more than one answer when i set it up. not looking for snapped belt carnage, just detonation related damage

[Turbodave]

Since most turbo cars came with 782 heads (7 years of production) I have a strong feeling that the poll is going to just echo that.

It would be a lot more informative (and also nearly impossible) to show the overall percentage of failures for each combo. But to do that you would need to know how many people didn't burn a piston.

Anyhow I've had 4 cars with holes in the pistons, all with 782 heads. The funny thing is that 3 of those cars were TBI and never saw boost?

[Directconnection]

Too many factors to rule anything. Not talking about tune... but people putting G-heads on their cars were probably 1986+ swirl headed/calibrated cars. The g-heads need more timing and he swirl headed engines had different pistons which lowered compression and the calibration had less advance because of the fast burn chamber. These 2 factors will screw up your answers.

[2.216VTurbo]

Well, I've never burnt/broken a piston with a Masi Head or a Lotus head so that leaves G and Swirl/782. Burned pistons with both of those...

[Xtrempickup]

true, but if everyone burned more 782 heads than anything else regardless of tune, everything being equal as in all on turbo cars, wouldnt that be more incidative of a 782 head set ups being more prone to failure. a lot of ppl have run more than one of the heads listed, so honestly if you have destroyed the 782 on a set up and changed to the ghead on that same set up car just adjusted to compensate for a g-head and it hasnt budged what you would that say? how many stock or modded early TI 84-85 G head cars have detonated pistons? these were cast piston cars also. If i have to vote on a head that can take the most beating, i'm seeing what comes out of this thread as there are many gheads on later set ups where 782 have failed already.

[Directconnection]

I would put my money on the swirl heads if everything were the same (more detonation prone) due the much talked about quicker pressure rise.

Whomever responds that their g-head cracked/didn't crack pistons vs a swirl head shoudl also mention what pistons they used (dish size) and what cal. Then you can get a clearer picture.

[Frank]

I beg to state that I think the results would be invalid because of lazy people or even inexperienced people not doing what it takes to properly tune the car and then burn pistons.

[Xtrempickup]

even properly tuned cars fail dont they

[Frank]

Yes, but I have seen so many people burn up pistons for not caring... I dunno. It just seems excessive. I memory would go for swirl, but there are so many out there....

[cordes]

For what it's worth I recal Stephan stating that he did not have to pull as much timing as the boost went up with the 782 heads.

[moparzrule]

^ I believe that to be true. I had to pull a good bit of timing in high boost (although I added TONS out of boost and up to 10 PSI or so) with my 2.5 G head combo, it's the reason I believe that G headed 2.5's have high EGT's. However, I still believe with a G head it's more forgiving. I'm running 25-28 PSI on pump 93 octane, 1700 EGT's, stock mahle pistons. No failures, got the CEL flash on knock on and I maxxed out timing advance. IMO it's because I'm only at 1700 for a brief couple seconds, it's prolonged heat exposure that melts stuff. One time I was doing my own cal, forgot to enable the CEL flash. Did several WOT runs, raced a mustang, 24 PSI boost or so. Found out that it wasn't on, didn't change anything to the cal besides the CEL flash on knock back on, and the light came on at about 14 PSI yet I was running it all the way to 24!

[DBB mini]

Supply & demand. More rookies start out frying pistons with the swirl head than any other hands down, more readily available & victim to careless mods. Moreso operator error than characteristic of head design. Get a cal or advise from a buddy rather than read the plugs or invest in a wideband, pyro, etc.

My .02

[contraption22]

There are probably a dozen or so varaibles that would be higher on the list of possible causes of piston failure before I started trying to find a link to the cylinder heads.