This is the thinnest area of all pistons for a small ford, detonation, lean are the causes. As far as the explanation from the builder, well ..............

 

I'm guessing not having a tune may have done it, never a problem from that engine builder for myself...

 

Curious what, if anything CHP will do for you.

 

Really?

Why?

 

Im with Woody, melting a piston is really evident versus breaking a ring land off because of detonation. Lack of fuel.

 

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The blue line is the first pull (how it was running while I was breaking it in)

Red is the tune by DGR Performance


It was also the #7 and #8 cylinder pistons not 6&7. Sorry.

 

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Did i miss where it tells us what those pistons are (hyper?)

 

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stoksuks- I dont think CHP would do anything. I got the kit. Had Hammacker's Engine shop install the short block. Then I put the rest together and into the car.

I just don't want to put this car back together (got -20.10cc pistons for 9:1 compression for t/c s/c) and have the issue happen again. Could there by any other causes than running lean?

 

No sir. Any time you knock the top land off next to the intake pocket, it was lean.

 

Detonation... and or ring butt... But if ring butt was an issue it would have popped em across the block.

It was going bang bang bang, and those were the hottest/worst of the group and the first to fail.

 

Can you explain the ring butt possibility. What do you mean " across the block"?

 

K. So I can probably assume this happened before I got it tuned? Or after?

On the sheet you can see it was running lean from 2,000 rpm to 3,000 rpm. I daily drive it and drove it 500 miles like this.

They are PROBE FORGED SRS Pistons

 

If you were babying it during the break in miles, I would say, that wasnt your problem. Most likely this happened after a few good hard pulls. Even the afr after the tune appears to be lean. I would feel more comfortable with my daily drivers afr in the 12's at WOT.

Were you using the shops muffler mounted wideband? Or was the 02 sensor screwed into your header collector? There can be as much as a 1.0 difference in afr just between the placement of the sensor.

 

If it were me I would upgrade to 42lb injectors and get a tune.

I am by no means an expert though.

 

The blue line is very lean in every spot, the red line is just lean. (the red line I read 13.34 at the end?)

 

What the heck are those marks at the top of number 7??? I'm guessing its the from chuck of piston that cam off? I've seen pistons like that before, from a stock engine though.

 

goody_seven- it was between 13 and 14 the whole time after tuned

86mustang408w- it was pieces of the top ring...an inch piece of the top ring broke off in that cylinder. Thats what made all the noise and made me aware of the problem.

DGR performance had to make a bung in my exhaust for his sensor

justhereforinfo- I was babying during breakin. Which means I mostly drove it between 2,000 and 3,000rpm which is where it was running as lean as 17. This is why I thought I may have caused the damage before the tune.

EVERYONE: I am going to be running dished pistons and a compression of 9:1. Will a/f ration of 13-14 be alright?

 

Running lean at part throttle isn't as bad as running lean at wide open throttle. An AFR of 13-14 is still lean at wot. I would shoot for 12's. I'm not positive on this, but dropping the compression by two points may richen your fuel mixture. Or, I should say, it may require less fuel.

What type of tuning device did your tuner use?

 

I bought the SCT Chip. I'm guessing he used SCT program to load onto it.

Question: any suggestions how to break the motor in? My engine builder actually said he breaks his engines in on the engine dyno and does around 3 pulls. He said I could probably take it to get tuned and have it broken in the roller dyno.

 

Roller engine break in, start it, check for leaks, drive it like you stole it. best thing is city driving or drag racing. Worst thing, cross country trip on the interstate. Want a handfull of Varied RPM hits with compression and vaccum. Your just seating rings, doesnt take any time at all.

Typical race engine break in... start get warm move rpm around between idle 1100 or so to about 3000. Check intake torque, head torque, leaks timing etc.

First pull, medium load, up to about 80%, check fuel curve and initial timming set.

Second pull..regular break. scare the hell out the owner and run it out to the point where the power falls off.

from there on, tune it and run it.

honestly within about 3 minutes of total engine run time, mine was turning 9000 RPM

 

Why was it leaned so much??? I would never have let it run like that on the dyno or the street???

 

We originally thought my used heads had 72cc (based on part # and AFR website) so we thought it was 10:1. However, they are 58cc and I was definitely at 11:1 compression. So tuning should really keep a/f ratio between 12 and 13?

 

Shoot for 12.5 if using 93 octane pump gas. If you are having it tuned at a shop why aren't they giving you this information?

 

If I am reading that right , says 13.34 ?

 

You read it right, he is in desperate need of a new tuner.

goody_seven- it was between 13 and 14 the whole time after tuned

 

talk to Frank @ PSI Motorsports
PSI Motorsports Inc.
not much on his website, but he's good

PSI Motorsports has moved. Below is their new contact info and address.
610-900-4900
500 Little Gap Rd.
Unit 1
Palmerton, PA

this car is his latest beast..saw it at the track running 7.60's..####in nasty lol
http://boccellasperformance.com/sponsor-cars/videos

I had mine done by Chris Rose at Tillman Speed near philly..
Tillman Speed Inc. - Performance Since 1979
he now does the canned bamatunes for american muscle,but i believe he still does the tuning for tillman's...that was over 3 years ago,no complaints, a/f 12.7-12.8 @ WOT..car was on the dyno for 4-1/2 hours..Frank is probably more $,but closer to you

 

Well the dyno sheet says DGR , and from the looks of it that was a place called SGS , and then before that it was called Kauffman's , if you do a quick google search looks like this guys has grenaded a few motors even since the days under the Kauffmans name , I know of 2 local guys around me that had work done at Kauffmans years ago on Lightning trucks and then after blowing engines both are doing there own tuning now ......

 

I know someone has already said this, but ill say it again.

Part throttle cruising at 16-17:1 will not break a piston like that. every motor is different, my cam has a bit of overlap, and is perfectly happy cruising at what would be considered lean air/fuel ratios. When it goes WOT throttle tho, it is around 12.5:1