I managed to warp the seals in my brand new motor for the second time. The first time came in feburary 19th, 2008 after a 6 month rebuild. Motor was built by a local guy that you guy might know chris rogers "Mr. rx7 tt" from Va. beach. Great guy and great builder, but for some reason this engine keeps warping seals. Forward to two days ago. July 08th, 2008 I go back to Ray @ PFsupercars to get tuned again and the samething happens. After being on the dyno for a few pulls and tuned we ended up with 420hp @16 psi on pump/c16 mix and warped seals. Engine still runs but wont hold an idle. I havent done a compression test yet, but from knowing what happend last time I can almost bet you that the seals are warped again.

Back ground on the engine:

Built by Mr. Rx7 TT
Tuned by Ray PFsupercars
Street ported
Exhaust ports opened
oil mods
3mm mazda oem apex seals
PFC
Dual mocal oil coolers / mocal stat
Greedy IC
NGK 10.5 trailing
NGK 9 leading
850cc
1600cc
omp still hooked up
premixed 1/2oz to a gal. using IDEMITSU

first time this happend the engine maybe had 50 miles on it. We came to the conclusion that I did put enough premix in her. Even thought the OMP is still functional. This time the motor had about 2k break in miles and the same thing happend.

Ray @ PFsupercars monitored for knock, a/f was @ 11.5, boost was at 16psi steady, and the car sounded good. Do you guys think there could be something wrong with the clearence on the rotors from the 3mm job. We are thiking in using another set of rotors with mazda oem seals

 

Drive it out, they'll re-seal on you.

 

what are the chance's that the will break instead of resealing?

 

sounds like its a likely culprit, if everything else went fine then i'd also assume the 3mm machining was at fault.
i do agree to just use stock 2mm seals.

 

how big of a street port? could be a corner seal issue causing the low idle/holding idle problem?

Tim

 

Have you confirmed your OMP is working properly?

 

do a compression test to find out what actually is wrong. it could be an apex seal or it could be a side seal.

 

What were the exhaust gas temps? When you opened up your last engine, what did the Apex seals look like?

 

what kind of exhaust ports are you running , are they the "square" ports?
those supposedly tend to warp seals

 

Is a normal-large street port. At least that what i asked for when the engine was built. Well last time this happen the center of the seals...mainly the rear rotor was worn. The corner seals looked fine.

YES!! i also ran heavy on the premix

65-70 psi on all faces.......yes its low. This was done at pfsupercars.

No EGT's..... Center on seals worn and flat.


Couldnt tell you. I know they were opened up and matched all the way thru, but nothing crazy... Hope that makes sense.

 

having similar problems here in the UK....rebuild (bridge and T51R kai) and run in 1000 miles, boost on for 400 miles (460bhp 1bar) and one cracked when the boost started spiking at 1.5 bar, replaced seals for the 1st time. 400 miles later and seals warped but engine still running.....changing seals for the 3rd time. using hurley 2mm one piece originally as they tend not to break but moving onto 2mm 2 piece unbreakables.

Advised warping can be to do with heat soak and this was my underdrive pulley kit being too small and water not circulating after 6000rpm so everything getting too hot although defi guage reading 95 degees water temp.

Flat seals in the center may be heat soak as they touch the plugs with expansion (its not a seal fault). Can also be to do with not running ignition amplifiers or old coil packs not doing their job at high revs.

 

I assume the exhaust ports are properly beveled?

 

it took repeated, audible detonation to warp my 2mm RA Super Seals. Double check the machining of the rotors or switch seals

 

Do you have a picture of the rotor housings in the area of the spark plugs?

This is where most of our problems start.

Barry

 

who did the 3mm on the rotors..

 

420 RWHP- What fuel pump were you using?
John

 

Causes:
(1) poor clearancing.
(2) insufficient lubrication.
(3) insufficient rotor housing cooling.
(4) EGTs too high.
(5) exhaust port design too wide, non beveled edges, port closes too fast.
(6) bad apex seals.

 

Do you guys have pics of non beveled edges, exhasut port too wide and square ports so we know what not to have

Comparison pictures of GOOD against BAD would be great if you have the time

 

The stock exhaust ports have a 2mm bevel designed in so that the apex seal does not hit a knife edge as the port closes. When the rotor housings are ported, this factroy bevel is ground away. Therefore it has to be re-created after finishing porting. Any reputable engine builder should know this.

 

What fuel pump were you using?? You probably ran lean on the top end and it did not show on the wideband. I have seen this happen with the walbro pump and the cosmo pump at the power you are stating. The apex seal warp due to a high-heat/lean condition. Check your fuel pressure on high rpm pulls- you'd be surprised at what doesn't show up on a wideband. The symptoms you are stating are directly due to a high heat condition.

John

 

It could be caused from porting the exhaust port too wied. If exhaust port is too wide it may cause the seal to flex under boost. Check and see if the engine is geting ported to wide.

 

This is what Chris also sudggested. I am running a single rotary performance pump. We ran some numbers and we came up that the pump is at its max at this boost level. I have not tested the pump to comfirm that it is starving at 16psi. The wideband was running 11.5 when we got into boost. IMO this is a very safe level. We also ran 5 gallons of c16 mixed with the 93 that it had already in it. I'm going to order an aeromotive 1000 pump and forget about fuel.

Well chris has build a few 100 engines and I'm sure he know how to port an exhuast port.

I was not aware of this. I'll check when the engine comes apart hopefully next weekend. I'm sure Chris know this.


1. no possible. everything has been mic to specs
2. possible, but I still run the omp + heavy on the premix
3. possible, but kinda hard to check.
4. we didnt monitor for egt's
5. according to chris all the ports are fine
6. 2nd set. ordering another......I hope this is not the case.

 

was there ever any conclusion to this?

 

It is still sitting in the garage. I plan to finally rip it apart this winter. I started building another car for drifting and this one took a back seat. I have tons of goodies ready to be installed for this motor.

 

Update from my engine after 2mm unbreakable managed to wrap themselves over one of the rotors..... thats the third set

Tuner advised likely cause is 'bounce' caused by worn rotors and housing and to replace them. with new......thats not a cheap job