I've been trying to figuire out what's going on with my 416. When I first got it running I did a compression test and all holes pumped 205 psi.
this is a 12-1 compression engine with a 50° ivc.
its always smoked out the breather.
newest compression test showed 7 holes 190psi and 1 hole 180 psi. The low hole was the same one i had a injector stick open

I leak down tested engine cold 6 out of the 8 holes and got 25%-40% at 40 psi supply pressure.

Car sounds different at idle from when I first got engine running. It sounds very tame and doesn't have the thump per say at idle it used to.

It also should have ran alot higher mph than the 133mph that it ran at 3100lbs. Probably closer to 140mph.
what's everyone's thoughts?
its leaking past the rings as I can hear it coming out the valve covers
Thanks

 

Hi. I always would "port" Bonami into the cylinder.
Lance

 

Can you elaborate on that?


OP, it sounds like you washed your cylinder bores. It looks like you've identified the problem, and you will need to hone the bores for new rings.

 

Costs less than purpose-sold "ring quick-seating powder", and is likely the same thing, just not re-packaged yet.

 

Bonami is a machinist trick going back 70+ years to get new rings to seat

 

"De-Glazzing" was taught to me BY Mike Costin.
YES it works!
BTW Perez AND Botox were SLOW by 3.69 seconds a LAP

 

Aston Martin even worse. I wonder if Alonso quits early. Such a shame.

Trying to keep an open mind on the new regs until the teams have it figured out, but it sounds really bad.

 

Yup, I used to use it too, before it was offered under the different name as a hot-rodder product.

 

Thanks for YOUR interest.
I was the person WHO caught Roberto Moranio a "ride in FA"
He won Willow that day FA AND I introduced him to my friend Carry Agapiou.
That year they won FA Champ and then Roberto joined F-1
Lance

 

 

That’s steam, not smoke. It’s the ethanol in the gas that causes that. Mine does it, as do all the builds I vent to atmosphere.

 

what's your thoughts on the leakdown results?

 

Id tear it down and run each cylinder with a dial bore gauge to see cylinder condition. Cylinder wall finish and overall condition is critical for retaining cylinder pressure. Bore size, taper, and finish will make or break you. My machinist is very expensive (NASCAR Shop) but we measure out to .0001 for taper AND roundness and I spec a Diamond hone for RA/finish. The more round the hole is after plate honing, the better off you are for rings to seal correctly AND last. Ring material choice is critical also if you want it to live. A leaky injector will hurt rings quickly because of the dry cylinder….which also hurts crosshatch, and likely your skirt(s) are wore also. Don’t ever never ever pick the least expensive machinist, if you’re looking for performance AND life.

 

You may not like the idea, but hear me out. Since you drive your hot rod, like I do, you might consider backing up a bit on the stroke and let the piston be more stable. If your bores are shot to the point of needing an overbore, you are buying pistons for sure. The more I build, the more I just do not like the 4.00 cranks in anything that gets mileage. The 3.900 cranks are better, let the piston be more stable and not pull the skirt so far out of the bore. Just depends on what you find. Since yours is an LS3 block, you can only overbore so much, 4.075-4.080 is about max.

 

The smoke coming out of breather is that on a cold start, if so, not so bad. However, if this after you have driven it say 30 minutes and you pull over and open hood that is not what it is suppose too do. Check catch can there is there a lot of water in there? If it has that much steam after hot how are you head gaskets / water levels? The 25% to 40% (loss) on a cold engine is terrible. Che70velle can maybe tell you an acceptable range but less than 10% on a cold engine. Both of mine are less than 5% cold and have a similar cranking compression to you. One thing that dual quad Dave eluded too is the reason your numbers maybe so high - is the piston at bottom of the bore? If so the reason the leak down number may be so high is piston is at bottom of the bore and is cocked sideways that with an out of round bore at the bottom will get you the big loss numbers you see there. Do the leak down test with piston at TDC and then rotate 180 degrees to BDC and see what results you get.

 

Can you do a hot leak down to verify? With 25-40% leak, could you hear where the air was going? Did you hear it out the breather, or was it going up into the intake? If you open your throttle body and you hear air you know it is the intake valves. If in the breather, it is going past the rings.

My LS7 would not smoke at idle when cold, but when the oil reached higher temps would push out the breather quite a bit - but I believe it is steam and oil contaminants boiling off. Worse with more ethanol content. It would really start doing it 200*+ when you reach the steam/boiling point of the moisture and really forced out the ethanol too.

I've been having the same back and forth...unsure if my rings are f'd or not on my 60k mile SBE LS7 with thousands of track miles. I have been pushing so much oil out of the breathers into my catch can it was ridiculous, but I think it was truly just a valve cover problem. I've been wanting to do a leakdown, but too lazy with how much of a pain in the butt it'll be in my rx7 engine bay to do a hot leakdown. I've also had the butt dyno telling me I'm losing power (probably just at the I'm used to it stage), a second dyno reading less by about 20whp (but I didn't believe the first one), more bucking and misfiring, higher engine and oil temps, and some less than expected performance results, but is all likely just in my head trying to make connections to explain the excessive oil from what I suspected was excessive blowby.

I swapped to LS9 valve covers, 10AN fittings on the covers, and Y'd the two valve covers into the catch can. I drove the car relatively hard for 1.5 hours on Saturday and had less than an ounce in it, and more than half of the liquid was clear contaminant with a little PCV sludge. I did a mild 2 hour drive the other day with my other valve cover and breather arrangement and got 10 ounces in the can and more overflowing with tons of smoke and oil coming out the vent.

PS - I put an exhaust extractor to the top of my catch can and it is one of the best things I ever did. When I had a breather to the engine bay, I had 3 instances at least where the catch can overflowed while racing and my engine bay and whole underside of the car has been just inundated with oil. I clean it, and more comes out lol. The exhaust extractor pulling the gasses and fumes away from the engine bay and passenger compartment has been a huge perk.

What ECU are you running? Not having the same sound at idle, maybe the fuel trims or timing tables are learning? You could reset your ECU and go back to the original tune and see if the pop comes back. My Holley definitely can learn itself in the wrong direction at idle and light load. When the O2 sensor sees misfires it can make an adjustment that makes it worse.

 

Spanks 13 - Anything specific on the LS9 valve covers that makes them better for overflow? So your catch can runs into the exhaust for the exit. If you have a dip stick on engine you can put your thumbs there to see if it is coming out the bottom end there.

 

The baffling is way better than any aftermarket solution. I don't know if I can link it here, but they're available from michigan motorsports for $150 a pair with gaskets and bolts. The baffle design is similar to LS3 valve covers, but the top of the cover is bumped up to accommodate a larger baffle volume without impinging on the rocker arms. The underside clearance is the same to an LS3. Also nice that the coil packs bolt directly onto them without a bracket, so they're a bit cleaner looking.

You can see the oil/vapor needs to travel from one end of the valve cover to the other. The red cap is the factory quick disconnect. There's a company selling press in 10AN fittings. You remove the stock fitting and drill out the hole to 9/16" and press in the 10AN. The factory fitting is for 3/8 lines, but the ID is less than 1/4".

I've had Holley, BTR, modified BTR, and now these. Road racing and autoX is a royal pita for oil control. I'm at the track again this Saturday and really hoping I can get through the day without oil drama lol.

And yes, we welded an exhaust extractor into the exhaust pulling on the top of the catch can. MightyMouse sells a remote exit that replaces the air filter with a 10AN cap. I had the can overfill a couple times with the exhaust extractor and all I had was some oil residue on my rear bumper instead of half a quart of oil inside my engine bay lol. Honestly got very lucky that nothing hit the headers and decided to flare up. MightyMouse recommends relocating the breather behind the car or into the airbox for road racing and I see why.

Sorry for the derail, this hits close to home lol. I feel your pain OP.

 

I did a cold leak down and #6 was 35% then warmed it to 200° and it dropped to 28%.
I put the piston at TDC on the compression stroke. You could hear the air coming out the valve cover breather holes. I even loosened the rockers up on that cylinder when it was reading 28% just to see if the valves might be hanging open. That didn't make a difference. I couldn't hear it coming out anywhere other than crankcase.
im using the terminator x with a ATM 1050 carb. My terminator burnt a injector driver on #6 and caused the injector to hang open amd almost hydrolocked the engine.
I had a few so called tuners tell me my tune was off before I found the burnt driver. So I ditched the port injection and just use the terminator for fan, trans, gauge control along with the data log feature. Kinda best of both worlds.

 

I had a terminator X fail on me too. Randomly out of nowhere the battery voltage read ~7 volts when the battery was fully charged. The rest of it worked, but I didn't trust it anymore. Look it up and it is a common failure and Holley can't do anything for you.

Those are definitely high leak values, especially when warm. Sorry to hear it wore out. You've inspired me to try and check mine tomorrow.