Red-Rx7

Here are some pictures from my engine that blew back on June 21st, 2001. I was at the race track (road racing), and was at 6800 - 7000 RPM passing a 1997 911 twin turbo porsche.













The engine had some what low compression at the time. My AFR was in the 11.5 ranges. Not sure, but it just gave out.

It was a Pettit rebuilt block, with 3mm seals (Ceramics).

Open for conversation! The dent measured near 1/2".

rxtasy3

iTrader: (2)

From what I've read in the past, carbon seals would not have caused that damage.

j9fd3s

iTrader: (3)

ceramic is not carbon

Boostn7

Hmmmm....that dent clearly says it all...>>heavy signs of detonation at some point.

JD

matthewpims

yeah I was about to say damn! no apex seal could of made a ******* dent like that, some serious pinging!

gambone

iTrader: (3)

Got one just like it, happened at Woodburn Drag Strip. apexs seals came apart and onec or twice around and them little piceses do a good job on them houseings. I think the deal is the ex ports are to big and the apex will flex as it passes over them BIG ports at the higher Rs and sooner or later it will brake, that's my thinking

peejay

Apex seals *can* dent rotors when the engine turns into a sort of giant, self-inflicting coffee grinder. I have proof in my basement. Munched the rotor so hard it even punched a hole through to the oil in one spot.

That rotor housing looks *old*... it has that milky, hazy look of worn-outedness. How long was it in service? (To the point, were the ceramics installed on *new* housings?)

RX794

What kinda boost levels were we talking when it went? I think you needed more fuel, 11.5 is too lean for WOT, especially on boost.

RETed

They can make a dent, but NOT a shallow smoother indentation as clearly shown in the last pic.

Stock FD rotors are especially prone to this problem when there is detonation due to the thinner rotor surface.

Do you own an FD?  I thought you were an SA owner...


-Ted

Maxthe7man

That dent is about the same dimension as the folded lip of the seal groove, which to me says that the dent is from the apex seal piece being pinched against the housing by the rotor, which incindentally is about the the same size as the exhuast port, where the chunk probably went...
Whats interesting , is I had a similar melt down on a 3mm motor about a 1 and 1/2 ago, on a dyno, and I am glad you posted those pics and stuff... I think this kind of melt down is really caused by the milling of the rotor, and bad fitment of the seals rather than detonation, there was no sign of any detonation on my dyno runs,the fuel was 91 oct, the a/f's were in the 11.1-11.4 range timing was at 15 deg, intake temps were low, boost was a mere 12 psi... This motor had low compression as well, and was a rebuilt that had only had 10,000 km's on it, it came with my car when I got it...When I tore this motor down, I found the apex seal milling was not centred on the rotor tip, it was offset to either side on each tip which means each rotor face had a slightly different combustion volume and port timing, and on top of that the seal grooves were not straight, they were "s" shaped along the length of the groove, I think the seals start to flex and get cracked, and then a chunk pops out and the motor consumes itself, and because there are dents, people always think its detonation, but its just a where the peice of the seal hit the rotor face....Max

Red-Rx7

Hey all.

The engine went out in June of 2001. It has been sitting together since then, until recently.

I was running 12 PSI at the time. I have had this engine ping a few times, but it always recovered fine. There is an old video on the web of me on the dyno and you can hear it go PING PING PING PING real loud so fast. This was due to a corrupt map in the computer of the haltech.

But, it has pinged 8 times in its life. Each time, it did not kill the engine, surprisingly. Most of the times were near or at the same time.

When it was at the track, it didn't give any sign of detonation. Yet, we were also racing down the track at 6800 - 7000 RPM with the windows down @ WOT too. I didn't hear it ping, but obviously something happened.

RX7Wishing

yea, it commited suicide.

dont worry i have low compression right now too. and leaky turbos.. Goddamn FD's...

peejay

I remember getting that video from a link on the old "Big List". You could *hear* the sphicters puckering as it happened.

patriick

iTrader: (3)

Where can I get this video now? I've always wanted to hear what a pinging sounds like.

Red-Rx7

I am not sure where the video is. Ryan use to have it hosted, but it may begone forever now.

It was on the dyno, and you could hear it ping 3 times in a row. You could also see the black smoke come out when it did.

It lived through that, and about 7 other pings.

peejay

The video as I have it is called "PA210004.MOV". Yes, a Quicktime video. 5,014 kilobytes. My version is dated 2/18/2001 so the original is maybe a week older than that.

I counted 7 pings, by the way.

edit: It is at ftp.zeroglabs.com, in the Car_Movies/movies1/ directory.

patriick

iTrader: (3)

Downloading now...thanks peejay!

Red-Rx7

7 pings? I counted 3.

Yes, that is my car. I guess this can show the strength of the engine? I made 341 rwhp @ 12 psi with the engine & stock turbos, then tried to squeze more out of it. I went to a local dyno place, toyed with the maps a tad. It pinged 4 times on the dyno that day.

I then reset it all, and Steve K & I went through many things. A few Aussy guys recomended that I change some of the split (making it near no split for more power). So, I did. I didn't do it on the dyno, but did it before that trip to St. Louis.

The drive to St. Louis felt great. Didn't ping, made some very fast runs, etc. Then we get on the dyno, to show @ 12 psi trying to hit 350 to the wheels.

First run, that occured. I then went back and removed the split changes. The car ran fine, still had great power like it did origionally.

But, being silly & having a Haltech, I decided to play more. I really liked the setup too. I had the Haltech run my sequential twins. It was neat being able to turn on the 2nd turbo sooner than the normal, for a tad better RPM band. This made me have the best of both worlds (sequential & non-sequential).

Anyways, I went to the dyno once again. Made some more changes (Map sent to Steve K), and it pinged once again on the dyno in KC, twice.

So, I put the old maps back in, and it made good power. It did loose some power since the origional configuration of 341 rwhp @ 12 psi, but was still in the 330+ range.

So, upset about that, I went to a single turbo. Never got the single turbo to run right. Various problems, cheap quality on parts on a few things, etc.

With the single turbo, I know I pinged the engine at least 4 times, with 2 different maps. It was really odd, for the maps were suppose to be very safe from Steve K & Matt (Hitman).

Well, after finally not having it ping anymore, it didn't make the power it should. 12 PSI was about 310 ish at the wheels. It fluxuated it seemed.

Compression test showed:

Front rotor: 5.4 - 5.6 - 5.6
Rear rotor: 4.0 - 3.8 - 3.6

So, I decided what the hell. I took it to the race track (road racing) and made it out there on 4 segments. Each segment was 20 minutes long, and I was boosting 15 psi. Man, did that car fly around the track.

The last segment, a few minutes left, passing a Porsche 911 twin turbo "s", it blew.

What you see above is the damage from blowing it up at HP Topeka, and its ping history.

I had Iannetti Ceramics in the engine. It destroyed my turbo, taking a dime size chunk out of each blade.

Come to find out all in the end, I put a timing gun up to the engine bay before the HP Topeka event. Something I never did, assuming the stock BDC TDC, etc were correct in the haltech.

I was off 12 degrees or so compared to what was in the Haltech base timing in the setup.

patriick

iTrader: (3)

12 degrees advanced?