Matt @ FSP

Just a comparison for everyone. Here is the LT1 style seal vs. the LSx style seal. Cost comparison wise the LT1 seal is about $7 retail and the LSx is about $25 retail.

Translator

Damn... No wonder those LT1 seals are prone to leaking, LOL

Higgs Boson

So we know the problem....what's the solution????

Theta

Re-routed PCV system is the current solution.

Higgs Boson

Well I agree its something, but not a fix for a weak/cheap seal. Seems like the solution would be a strong/expensive seal.

Theta

True. To be honest, it sounds like a tremendous aftermarket opportunity!

0East Tx Muscle Cars

All we did was take the LS1 seal and trim it down to .300 to make it fit
seals perfect and is SO much stronger. until you hold one in your hand you don't really get how crappy the LT1 seal is

the rear main seal is the same exact seal so we are all good there!

Theta

Yet another adventure in cost cutting! Or, perhaps a bit more nefariously, a warning shot to those looking to slap on forced induction seeing as how these blocks are so strong otherwise.

Theta

Now find a way to make that process quick and easy and market that for a nominal rate. Good way to save people time and make some money doing it!

slief

It will be interesting to see what seal they use on the C7 Z06.

robertf97

FWIW, The LT1 seal has a pressure energized lip where the LS seal doesn't. When the LT1 seal fails is the seal coming out of its bore or is the lip blowing out? Is that used seal a failed one?

Matt @ FSP

Seal did not push out of the bore, oil pushed from inside (Balancer lip of seal).

Yes that is a failed one.

robertf97

Thanks a lot. I've worked with a lot of linear and rotary shaft seals and 8 psi or whatever a blower adds to the crankcase shouldn't hurt the seal unless it is defective or improperly installed. That lip is actually supposed to squeeze the shaft tighter the more pressure is applied. Since the case is shorter than the LS seal, my first guessis some are skewed to the crank at installation.

Matt @ FSP

It is not even 8psi hitting the seal.. Steve @ ETMC did a crankpressure test, he was seeing 3psi I believe on the "worst" PCV/evac setup and about 1psi upstairs after rectifying.

Unreal

Crank case doesn't see boost. Any pressure is from leak down and making it past the rings.

Andy@A&ACorvette

Not only is the LT seal really weak, it's reversed. Pressure pushes the seal AWAY from the crank. It doesn't take much.
I had a fixture made for my lathe. You pop the seal in and in about 30 seconds it's trimmed and ready to install in an LT motor.
Upping the crankcase vent to 5/8" and installing an LS seal should do it.

flflatrate

Seems to be a global issue this seal. Was at Redline's shop the other day and that had the same seals laid out on the bench and showed me how week that lip is.....I don't understand the logic behind GM lightening up that seal when the old seal worked fine!

Redline Motorsports

Matt,

Thanks for posting those. The root of this issue is more the excess crankcase pressure then a seal although this new seal design is not helping.

Blow by in an engine is an inherent dynamic that exists. Forced induction just compounds the issue even further and when the factory PCV system is not well designed and then they use seals like Matt has show your bound to blow stuff out.

I think the return of the older style seal is a great enhancement but the pressure needs to be dealt with. We have a couple C7's down to the bare blocks and have dissected the system like a 5 grader with a frog in biology class. There are some valving issues that need to get addressed but the bigger issue is crankcase volume. I'm curious over time if the dry sump cars are more prone then wet to blow seals as the crankcase area is small. We are working on a expansion tank with built in catch can and have up sized the feed and return lines quite a bit to allow additional crankcase volume to at least leave the crankcase and not look for a place to push....in addition to the leak potentials there is also the excess pumping and windage that is going to most certainly effect power output.

Be warned that anything that adds additional cylinder pressure to the combustion chamber will increase blow by........this includes detonation. Detonation can raise cylinder pressures upward of 3000 psi and no ring set will keep it from getting into the case......food for thought.....

HT

Late Model Racecraft

You are correct, detonation can cause oil/blow by to get past the rings and in turn push out the weakest seal.(front seal)

Solutions right now are to install a more efficient breather system and do NOT detonate the engine.