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-   -   Got lucky... (https://www.rx7club.com/race-car-tech-103/got-lucky-935771/)

D Walker 12-27-10 04:36 PM

Got lucky...
 
Well as no one but me is likely to remember, when the FC ran the PIKES PEAK hillclimb the engine stopped and would not restart, so we ended up 7th out of 8th. Which kinda surprised me since we didnt cross the finish line, but hey we will go with it. When we got the car off the mountian there was no fuel in it (bone dry) and the turbo drain hose had split so no oil in it either (also, bone dry) so we had multiple reasons the motor might have stopped. A little surprised at the fuel usage, I would have thought we would have done better than to use 8 gallons in a bit over 12 miles, but ok.

So I had little doubt that whenever it was torn the down there would be 0 useable parts in the engine, and went ahead preparing a S6 motor for it. Since it is getting close to season, and its warm here, the wounded powerplant got yanked out today. I started to just set the old keg on a shelf, but figured why the hell not and tore it down anyway.
What I found was-

Definitely ran low on oil, rotor bearings both copper all the way across. No damage to the e-shaft.
Since it was running on e-85 and had maybe a dozen hours on it while still running pump gas, the rotors are pretty damned clean, along with the apex seals, corner seals, etc. Some weird "shiny" areas on the rotor face near the bathtubs which I believe are the results of the bearing wear.
Front and middle plates are very good, but will get lapped anyway. The rear plate was, as suspected, cracked at the dowl pin.
Many, many things were loose that started out tight, including the alternator through bolt (nut vibrated loose), turbo manifold bolts (snug but not as tight as they were installed), and a few other surprises.
Also a surprise was that the motor was completely un-ported, but that is actually a really good thing as it allows me to port them all up the same.

Overall, the motor I thought was a throw away was in pretty decent shape, and so the plan is as follows:

Send the housings out to Goopy to resurface
Send out the irons to be resurfaced if time allows
Replace the rotor bearings
Check and replace stationary gear bearings if needed
Replace cracked rear iron with a spare S6 iron we have here
Port irons and housings using the Pineapple templates I like
Send out the Goopy Performance corner seals to be Casidiam coated
Assemble the motor using Goopy Performance O-ring kit, apex seals, etc.

and keep on-hand in case its needed ;)

My only real concern at this point is the weirdness with the shiny rotors, Its not pitting or detonation damage, but its shiny and weird. If it comes down to it the rotors can simply be replaced with another set as they were NA rotors to up the compression, and I have a pair of NA engines here with perfect rotors :)

I also might try some different things with this build, like Nikasil coating the irons and housings after resurfacing, Casidiam coating the corner seals where they contact the irons, and maybe DFL coating the bearings. I have considered coating the lower intake runners and intake ports with a ceramic coating to limit heat absorbtion, but that might be going a little far.

Anywho, the car dodged a serious bullet and the little 13b will live to fight again another day. I took some pictures and will post them when I get home.

peejay 12-28-10 12:01 PM

Any telltale marks on the narrow points in the rotor housings, especially the one above the exhaust port?

D Walker 12-28-10 12:49 PM

Actually, other than some minor scoring (they are well-used housings) the housings look really good, which surprised me. No cracks around the plug holes, and in the first examination prior to cleaning I sae no pitting, dents, or other bad bad things in the surface. Pretty sure the last guy who assembled this engine put it together with the housings already a bit scored, as they were trying to get a motor together to go to a drift event. I will admit that using the E-85 I was a bit concerned about the premix ratio and added maybe more than needed, but as I said everything looks pretty damned good considering.
Also none of the corner seals were stuck or pinched, which also surprised me. The shiny spots on the rotors I believe was caused by contact with the housings due to the toror bearing clearances going away. Other than the scuffing/ scratches the rotors appear in good shape. As I said before, will not ruin my day if they are junk, but it would be a bonus if they are OK. Obviously they will need to be really well checked out, weighed, etc. before I go much further, but again, no real complaints here at all. I am also going to try and repair the cracked dowel pin boss on the rear iron by pre-heating it and then using a silicone bronze rod to TIG the bits back together. The Silicon bronze rod is more like a high temp brazing and I think it should work fine to do this, and if it fails miserably I am really no worse off.
Remember, this engine was running up Pikes Peak under race conditions and both ran out of fuel AND oil! It should be a melted pile of scrap metal, so I will be happy with what is here :)

I brought the better camera in today and will try and get some decent pics before I leave.

rotary everything! 12-28-10 06:02 PM

well, good luck with all that, i hope it all works out well...like i said before, cant wait...really want to see the results of your goopy stuff...im also interested in sending my housings to goopy and grabin' up some related parts from them...so im really excited to see how yours turns out...thanks man...
pics would be awsome, hope your camera takes a good photo.
thanks

D Walker 12-29-10 07:33 PM

Ok so I finally got a few minutes to upload the pics, and here they are:

Engine still inits home, untouched since the Hillclimb-

http://i218.photobucket.com/albums/c...r/IMG_0167.jpg

Did not even bother with the lift, just popped it up on jackstands

http://i218.photobucket.com/albums/c...r/IMG_0173.jpg

Housing, not terrible-

http://i218.photobucket.com/albums/c...IMG_3614-1.jpg

http://i218.photobucket.com/albums/c...IMG_3613-1.jpg

Cracked rear iron-

http://i218.photobucket.com/albums/c...IMG_3611-1.jpg

Scuffed rotor, they both have scuffing like this on each rotor face

http://i218.photobucket.com/albums/c...r/IMG_3624.jpg

Worn bearing, literally all copper-

http://i218.photobucket.com/albums/c...r/IMG_3625.jpg

Can post more pics if you like

rotary everything! 12-29-10 09:39 PM

yeah if you got the time, i'd love to see how your housings and rotors cleaned up...
did you put it all back together yet...? how's the compression?
im also really curious about the clearance of the housings and apex seals...did you pick up some apex n springs from goopy too...? if so, how do they look/feel...look like they'd hold pretty strong?
thanks alot man, pics came out pretty clear except the bearing one, kinda blury.

D Walker 12-29-10 10:02 PM

Thats actually engine oil in the rotor, I havent cleaned it yet :)

The car is getting a S6 FD/Cosmo motor next, should be cleaned up in the next day or so and the apex seals etc. will be here. These housings and irons need to be sent out for resurfacing and I am looking into having them nikasiled after they are done up.

The other T2 motor we have here will be going together on Wednesday next week, as soon as some delayed small parts arrive (UPS says Tuesday).

I have not tried the apex seal springs Goopy sells, but they are on the list to try. AFAIK they are just OEM Mazda Inconel apex seal springs.

j9fd3s 01-01-11 03:34 PM

that actually looks pretty good considering....

D Walker 01-01-11 03:58 PM

Yeah it is. I was really very surprised, as I have heard the horror stories of bearings welding themselves to the e-shaft, locking up completely and destroying pretty much everything.

The more I look at the rotors the less I want to use them, good thing these are N/A rotors and not terribly expensive :)

RotaryEvolution 01-02-11 01:56 PM

the rear iron failed due to detonation's twisting force or too much torque if you're using a massive turbo in n/a applications with the weak casting S4 rear iron without engine bracing. most likely the detonation cycle happened right as the fuel pump went dry and subsequently leaned out the AFRs. the engine probably would have finished the race without oil but it may have cause even more damage as oil starvation scores the irons and rotor ends, usually rendering the irons at least, useless.

don't discount that e85 sucks down fuel like a camel in the desert. i always say you need to figure double the needs of standard pump gas when switching to e85 as it's really only rated at 55-60% as efficient as pump fuels are.

the rotor damage was from when the engine twisted during the detonation cycle and the rotor face tapped the compression side of the rotor housing and drug across it's face.

lastly, keep in mind if you run the S6 rear iron that the porting is very different from any FC irons and the LIM bolt pattern won't match the TII lower intake any longer, also would require using a modified FD oil pan and at least making a brace to seal up the rear engine mount holes in the rear iron. then you would also likely have to use an FD front iron, however the ports still wouldn't match the FC center so you'd have to then use all FD irons, fab up engine mounts and use the whole S6 intake system. i just don't want to see you put the motor together and say "damn!" when things don't fit right anymore. stick with similar to what you have now or go with the S6 and figure out how to remount it with the different engine mount system it uses.

D Walker 01-02-11 02:15 PM

Good input! Will try and answer as best I can ;)


Originally Posted by Karack (Post 10394246)
the rear iron failed due to detonation's twisting force or too much torque if you're using a massive turbo in n/a applications with the weak casting S4 rear iron without engine bracing. most likely the detonation cycle happened right as the fuel pump went dry and subsequently leaned out the AFRs.

Actually, what we have found is that the prior owner had an overboost incident on a cold engine which cracked the iron. He may have done some sort of repair to get through the one drift event he used the engine in, because when started and idling in the shop it did not leak oil, however as we backed the car out of the trailer to load onto the dyno, I noticed a "minor" leak. It only got worse from there.


Originally Posted by Karack (Post 10394246)
the engine probably would have finished the race without oil but it may have cause even more damage as oil starvation scores the irons and rotor ends, usually rendering the irons at least, useless.

I think the engine would have made it, we were less than a half mile from the finish when the motor stopped, and when I tore it down the rotors were still btahed in oil and there was no signs of burning.


Originally Posted by Karack (Post 10394246)
don't discount that e85 sucks down fuel like a camel in the desert. i always say you need to figure double the needs of standard pump gas when switching to e85 as it's really only rated at 55-60% as efficient as pump fuels are.

The fuel issue was a miscalculation on my part, as I had no baro correction over 12,000 feet and so it was basically 9 or 10/1 from there on up to 14,000ft or so.
Never said I was perfect ;)


Originally Posted by Karack (Post 10394246)
the rotor damage was from when the engine twisted during the detonation cycle and the rotor face tapped the compression side of the rotor housing and drug across it's face.

Yeap, thats the consensus, as the rotors will wobble like all hell when the bearing cleanaces get too loose or the engine overheats


Originally Posted by Karack (Post 10394246)
lastly, keep in mind if you run the S6 rear iron that the porting is very different from any FC irons and the LIM bolt pattern won't match the TII lower intake any longer, also would require using a modified FD oil pan and at least making a brace to seal up the rear engine mount holes in the rear iron. then you would also likely have to use an FD front iron, however the ports still wouldn't match the FC center so you'd have to then use all FD irons, fab up engine mounts and use the whole S6 intake system. i just don't want to see you put the motor together and say "damn!" when things don't fit right anymore. stick with similar to what you have now or go with the S6 and figure out how to remount it with the different engine mount system it uses.

I have been looking at this, and you are right its looking to be more of a PITA than its worth. I am pretty sure I can get an S5 rear iron without much issue, but I know others have used the FD rear iron, just not sure exactly how they managed it. I am already building an S6 engine mount setup for the car, so no biggie there :) Also no hurry on getting this engine back together since I am using the S6 engine thats ready to go together initially.

Again, thanks for the input and comments!
Cheers,
Don

RotaryEvolution 01-02-11 03:37 PM

i was wondering what that mess was on the rear iron... i've never tried to patch one even on my own cars when i've had rear iron failures, mainly because the pressure behind that dowel pin is at minimum of 60psi, i guess it just depends how bad it was. mine lost 4 quarts in a 3 mile range so it was pretty bad, nothing i wanted to try and patch together even to try to get it home on, that's some serious ghetto rigging there.. lol. if he was careful you can swap the rear iron without tearing the whole motor apart, or even pulling the oil pan off for that matter(use clamps to vice the rear rotor housing to the front iron while the tension bolts are removed).

the rotor bearing damage may have already been present from when he lost oil due to the crack actually.

those rotor housings don't look too bad for what they have been through but i wouldn't use them due to the chrome flaking, it will never really reach it's max potential compression even with high comp rotors, i would guess that max compression once broken in even if you cleaned the surface scarring would be ~85-90psi with new seals, as an example a good condition S5 non turbo should be in the neighborhood of 120-130psi. if they can be salvaged with nickelsil coating though that may be an option, one that i have yet to explore. you can see the steel sleeve beyond the face where the chrome is completely gone, aside from just the corner apex seal gouging.

but the last bit is arguable, that advice was coming from an engine builder where the engines are driven daily on and off the street. so long as you can get the engine started the only thing you will suffer on is low end torque from a standstill, once the engine is revving and in the power band the loss of power from compression is negligable from the gains that the turbo is putting out, making the low compression issue nearly nonexistent once up to speed.

rotary everything! 01-02-11 03:39 PM

can we get more info about goopy's work?
thanks man, this is a good read.

D Walker 01-10-11 10:20 PM


Originally Posted by Karack (Post 10394365)
those rotor housings don't look too bad for what they have been through but i wouldn't use them due to the chrome flaking, it will never really reach it's max potential compression even with high comp rotors, i would guess that max compression once broken in even if you cleaned the surface scarring would be ~85-90psi with new seals, as an example a good condition S5 non turbo should be in the neighborhood of 120-130psi. if they can be salvaged with nickelsil coating though that may be an option, one that i have yet to explore. you can see the steel sleeve beyond the face where the chrome is completely gone, aside from just the corner apex seal gouging.

but the last bit is arguable, that advice was coming from an engine builder where the engines are driven daily on and off the street. so long as you can get the engine started the only thing you will suffer on is low end torque from a standstill, once the engine is revving and in the power band the loss of power from compression is negligable from the gains that the turbo is putting out, making the low compression issue nearly nonexistent once up to speed.

I missed this until I re-read it before posting an update- the rotor housing is not missing any chrome, the dark spots are burned on carbon, I had not cleaned the housings at all before taking the pics. Even with some minor chrome flaking Goopys resurfacing will ensure good compression for a "race" motor.

The "new" FD motor is ready for assembly tomorrow, will post pics as I have them. Its going together with the following bits:

Goopy Resurfaced Housing, Pineapple port
medium ported irons
Goopy 3MM Apex Seals
New GSL-SE 3mm apex seal springs
Goopy Corner Seals
Goopy O-ring kit (Teflon encapsulated)
FD CS Springs
multi-window 'race' bearings
medium ported irons
side seals are a mix of new and in spec used

Injectors are stock FD secondaries as primaries, and 1600cc secondaries, still using E85. Still no OMP yet, as I have no time to wire it in, so premix is it. Still using AEM ecu.


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