Dodging a bullet
 

Today, I tore apart my car's previous engine, which was a half bridge ported GSL-SE engine done on the cheap - 160k core engine that was given to me in pieces, so I did an experimental port on it (experiment: FAILED) and threw it back together with all of the old seals. The corrosion in the cooling system was spectacular so I didn't deem it worthy of new parts.

The last event the engine ran before the new engine was finished was a two-day rallycross, the 2012 Great Lakes Division National Challenge. I placed first in class. On my way home, I noticed that the engine had very little power at low RPM. 3000rpm at city traffic speeds, you could floor it and get nothing but intake drone.

First thing I noticed was that the JB Weld that I'd used to port-match the FC intake manifold (the primary ports sit a half inch lower) was rattling around in one of the intake ports. I'd never had it come loose before. It was only held in by the gasket and luck. If it entered the engine, it would have been a 1/2"x1.5" spear of death. None of it was missing, although there was a big curl of swarf ready to break off.

Upon cracking the engine open, I noted that the side seals were worn flush with the rotors, the corner seals had no pop, and the oil rings were shiny across half the face. End housings were FUBAR with grooving, a sign of dust ingestion. Apex seals had no springing left and they stayed stuck in the rotors. The center iron may be salvageable, which is fine because the end irons are crap anyway - 6 ports suck and I have a pair of 12A end housings on hand ready to make this a proper 4-port like my current engine.

But the rotor housings themselves? PRISTINE. Still no chrome flaking anywhere except for a small divot next to one of the exhaust ports, just like when I'd put it together. FUBAR everything BUT the rotor housings? On a 3mm iron seal engine? That's impossible!

The extra goodness is when I was picking the rotors apart. The backsides of the apex seals had deep gouges where the springs rode, another sign of dirt ingestion. Dirt gets in there and has no way back out so it laps everything, thus the lack of apex seal springing. Then I got to the third seal on the rear rotor - it came out in three pieces.

My exhaust ports are big enough that it SHOULD have lodged in the port and shredded everything related to the rear rotor. But, it didn't.

So, at least some of these runs: were made on a broken engine....

2 things:

madness
ever tought of using an airfilter on this kind of track? :D

Oh believe me - air filter gets changed out every day, oil gets changed frequently, intake system gets smoke tested regularly to find leaks (the S4 inlet is horrible for leaks - silicone it on and never take it off!), etc.

This wasn't a particularly dusty event.

you did dodge a bullet or at least a piece of epoxy. unscathed rotor housings are odd. what's your theory on that rear? detonation? excess heat?

No idea. I never revved it over 8000rpm, had an 8000rpm limiter and I only ever hit it twice and that was a long time ago.

The apex slots are wallowed out pretty badly, the eyeball says .020", the grooves visibly V-shaped, so that and the lack of effective seal spring probably had something to do with it. All of the seals had no tension on them, the springs and backsides were that far worn.

I was wrong about the spot of flaking - it's doubled in size and is now halfway to the exhaust port, so I'm going to consider that housing to be done. Still have one good one left though, and fortunately the good one was the rear one, so I should be able to use it to fix my current engine.

Current engine has 1/4-1/2" chrome missing all around one edge in the rear rotor, according to the borescope, and both of these engines have relieved secondary bridges so the housings are position-specific.

I really need to switch to carbon apex seals, but gosh, I apparently don't have any good 3mm rotors anymore and the 2mm carbons are supposed to have horrible longevity. Mazda Motorsports shows 1-piece 2mm ceramic seals that allegedly are 3 seals for $200 but the information in the catalog is contradictory.

Chevy 3.5 with a mild cam is good for about 275hp, that's probably going to be my next move when I'm totally out of engine parts.

is that the LX9?

To be honest, I don't know the nomenclature. The non-VVT engine with the 3100/3400 style block, not the 3.5 with VVT and the same large bore/spread decks as the 3.9.

I already have headers for said engine, and you know those engines are barely 20 inches long bellhousing to the front of the damper. I'd been planning a 3100/3400 for a while now but the 3.5s are actually lots cheaper since they *never* break, and their heads are even better than the 3100/3400 heads. The 3.9-based engines have a different exhaust port pattern and my headers won't work as easily, plus the VVT is an added complication.

But first, we must use up ze rotary parts, because that's still cheaper than buying an engine and a trans and having a driveshaft made and deciding whether to use the GM computers or hack together a pair of Megasquirts to control the engine and the trans. At least, I'm fairly sure that a computer that controls a 4T40 should be able to control a 4L60.

its a GM V6 you could probably make it work with a distributor and one fuel injector...

we did one, and basically the injectors just ended up being ON and the advance was pegged @like 40 something.

so no tuning required!

yep. that sounds like the LX9.

don't worry though, the only reason i know is because i'm looking into doing something with the wife's Impala now that it needs an engine. so i've been doing my homework. those 60º engines are quite fascinating. if it weren't for the VVT and all the intimidating wiring and computer issues it would bring, my choice would be easy. that 3.9 .... :)

realistically though, i'm looking at either the LX9 or the L36 (the unrelated, bad-ass Buick 3.8).

i must admit, there's a small part of me wishing you'd run out of parts soon, now that you've revealed your plans. :scratch: i think i need some time alone at a confessional or something.

I have a lot of interest in those 60 degree motors. They're very compact and the heads flow really, really well for what they are.

Tinman put a Series II 3800 in one of his FCs because it's a turnkey 200hp drivetrain. The 3400 is good for that with a decent exhaust system and not the funky crossover-into-the-other-manifold stuff. (The left side manifold is a 1.25" diameter log... and they still were rated at 185hp) The thing I like about the 3800 over the 60 degree is the crank is less scary looking, it's split pins instead of the funkiness required for a sixty degree V6. But I don't think there are aluminum heads for the 3800, I don't think aluminum 3.8 heads will work with that block and TA and Champion want a fortune for those anyway, whereas the 60 degree stuff is already there. And did I mention CHEAP since GM flooded the market with them?

Both engines have crossbolted mains and all the other goodies, to boot.

The other option is to find a 3.4 Camaro engine, which is the old style block, and use my 3400 heads on it, for an instant 12.5-13:1 compression... or maybe a little lower after some chamber work to unshroud the valves a little better... But the 3.5 has other benefits for it like having the cooling outlet at the front of the engine instead of the rear.

But that's all off in the distance, and there's another direction I may go as well depending on some other factors, so everything is up in the air. For now I should have enough bits for one more engine, which means another year of running rotary. And who knows what other stuff I might get in the meantime. Might go turbo the year after that, which is a concept that I find more odious than going piston, but you gotta do what you gotta do :) Power corrupts, and all that.

get a mushroom filter with a sponge element. oil it with PJ1 motorcycle filter oil and put pantyhose over it. you can replace the pantyhose a few times per filter cleaning. just clean it with gasoline if it's a good quality element and it should be fine.

don't fuck around with dirt ingestion, it's worth losing a few hp.

it's cheaper too, i know you'll appreciate that. ;)

using just the right amount of oil though takes a little trial and error. obviously it's best to start with a lot of oil, this is for offroad use so it is tacky to catch the dirt but it is rather difficult to use too much. i hose the filter with oil, squeeze it by hand to wring out the excess oil then wipe off the outer surface with a rag then put the pantyhose over the clean/oiled filter.

Upon inspecting the GSL-SE intake manifold some more, there was dirt in the secondary runners but not the primary runners. So clearly it was not a filter issue but a vacuum leak somewhere.

This jibes with how the end housings were trashed but the intermediate is still somewhat okay. The dirt was only getting stuck between the oil rings and the side seals there. The wear on the intermediate can be easily explained just by the dirt/iron contaminated oil.

I was running the power brakes to the primary side of the plenum so it couldn't have been coming in through the brake booster. Without having looked very far into it, I'm going to guess that it was coming in through the plugged-off secondary injector ports. I epoxied them shut but there was always oil drool around them, and leaks usually go both ways.

i tend to not rely on my gut that i sealed up an intake well enough, no matter how much i put into paying attention to detail it never fails to have a leak. it's a good idea to just spray down the manifolds with carb cleaner to check your work.

Smoke testing. Find everything.

Holley carburetors are a zinc casted vacuum leak. All SORTS of places where unfiltered air gets through.

Were you using FC or FD corner seal springs? Also, can you snap a picture of housings with dust ingestion? I want to compare it to mine when I open her up soon. And I launch on dirt from 8k lol.

3mm seals means you don't ever ever exceed 8500 on pain of exploding. Learned that lesson twice.

160k mile old wire corner seal springs went right back into the engine. I re-used EVERYTHING :)

Here's a pic of the 6-port streetport that I built and killed in one event:

http://a4.l3-images.myspacecdn.com/i...c6402315/l.jpg
http://a4.l3-images.myspacecdn.com/i...0fd45b76/l.jpg

Mind you, if it's this bad, you will have no usable parts inside. The engine got me home and never restarted, it had basically no compression. Side seals were worn down to .105" high at the ends, oil rings were completely flat from filing themselves against the side seal gouges, apex seals were 1.6-1.7mm thick and the grooves opened up... everything but the rotor housings and the eccentric shaft were garbage. Dust gets in to the side of the rotor and has no way out so it just turns into lapping paste.

The interesting thing is that is also wore out a set of FD corner seal springs. The ends were worn square and were really sharp.

Killing THIS engine is why I bought the GSL-SE engine and just threw it together without any new parts. I had no idea if it was going to last me one event or a whole season. It was a very depressing time. I went overkill on eliminating ANY non-filtered air, keeping the air filter clean (I use Klotz oil), keeping the oil clean... and it worked, for a while anyway.

that ultra fine dust is a killer, at least with saindrails it isn't all that difficult to filter sand.

Yeah, our dust is pervasive... the lot at National Trail Raceway is a clay base, and the cars turn it into something like well-sifted flour. I had it come in through the zipper of my tent one time.

I fantasize about a giant vacuum cleaner truck that sucks up all of the dust berms that develop, then re-deposits it into the ruts after the event is over.

[Chester Cheetah voice] impressive, sir! :D


i actually came back here because that trainwreck of a Holley thread in the Gen I forum got me thinking of this comment you made. it will be interesting the next time i get to work on my brother's car to test for leaks because in retrospect, it would offer a halfway decent explanation of the few remaining issues it has. i can check the theory before i start the next version of the Megasquirt install on it.

A surprising number of the accessory mounting holes on the sides (choke bracket, vacuum secondary can) go through to air. I ended up siliconing the mount screws. The throttle shafts all leak, too, especially if the carb has miles on it. Improper return spring routing really accelerates baseplate wear as well.

It can be a PITA but the carb will be far happier if you mount the spring such that it is pulling directly against the throttle cable, so it is not putting any side load on the throttle shaft.

Bad:

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Good:

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