[DatBrotato]

Car went in to get a vengeance stage III cam package put in.
This included AFM delete, LS7 Lifters, Trunion rocker arms, BTR .660 lift double valve springs, head studs, and chromly pushrods.

Within 24hrs of receiving the car it saw 3 pulls.
On the 3rd pull I miss-shifted from 3rd to 4th gear and the car free-revved and saw redline(6850) and well...
the photos and video speak for themselves.
As you can see from the video this wasn't a 3-2 shift, it was a free revv with some momentum behind the rotating assembly.

Shop(Speedtek) is covering labor and machine work on the rebuild.
Shop claims they didn't do a PTV clearance check because it's a common LT1 H/C package
Vengeance refused to concede that any of the parts they provided could've been out of manufacturer tolerance.
Heads weren't milled, stock depth gaskets.

1 cylinder wall was marred and will require a hone.
Head is salvageable.
All pistons got tagged, 1 got windowed.
Time for forged drop-ins.

https://photos.app.goo.gl/4ULeAJ44xJ6H7MWa6
https://photos.app.goo.gl/1xcjh3PdrvVxPZtv9
https://photos.app.goo.gl/WsP59gXfHL19TKNx9
https://photos.app.goo.gl/WsP59gXfHL19TKNx9

[oldman]

Sorry, IMO I can't tell it is a free rev or a 3 to 2. The carnage looks like a 3 to 2, once all the valve bend up the engine is basically free spinning with no compression. So you really can't go by an exhaust sound which connotates there is compression.... I've heard GM does store the RPM in the ecu 30 seconds before any check engine light. I don't know if Joe Public has access to this. I highly doubt a human looking at a tac after the event happens during a race can tell what maximum RPM an engine went on a 3 to 2 clutch in miss shift, the tac and human reaction are just too slow.

I DD a 9000 UP RPM capable engine, and over several decades I have done 1 3 to 2 miss shift off the cuff calulations the engine saw 11,000 RPM, I told myself it was not a 3 to 2 just a free rev-miss shfit, there was only a slight tick to the engine for like 2000 miles before a valve let go... No way the tac and human interaction can tell the actual RPM.

Heck I've no lift "free rev" shifted my Camaro more than 1000 times... FYI.

[DatBrotato]

Originally Posted by oldman

Sorry, IMO I can't tell it is a free rev or a 3 to 2. The carnage looks like a 3 to 2, once all the valve bend up the engine is basically free spinning with no compression. So you really can't go by an exhaust sound which connotates there is compression.... I've heard GM does store the RPM in the ecu 30 seconds before any check engine light. I don't know if Joe Public has access to this. I highly doubt a human looking at a tac after the event happens during a race can tell what maximum RPM an engine went on a 3 to 2 clutch in miss shift, the tac and human reaction are just too slow.
I DD a 9000 UP RPM capable engine, and over several decades I have done 1 3 to 2 miss shift off the cuff calulations the engine saw 11,000 RPM, I told myself it was not a 3 to 2 just a free rev-miss shfit, there was only a slight tick to the engine for like 2000 miles before a valve let go... No way the tac and human interaction can tell the actual RPM.
Heck I've no lift "free rev" shifted my Camaro more than 1000 times... FYI.

It wasn't a 3-2.
You can hear it bouncing on the limiter.
I also distinctly remember missing 4.
Top of 3rd into 2nd would've been VERY violent, the rear end would've stepped out hard, or at the very least there's a be an abrupt decel.
I've never 3-2, 4-3, or 2-1 shifted a car

[NickyRacerBoy]

I tossed rod threw block on stock motor on road race course.
I too busted valve off but it exploded piston and rod whipped around with wrist pin and windowed block and sawed oil pan��
Watch for debri in your intake manifold. I had to replace all the way to even the roto Fab airfilter.
I had total loss.
New motor cam phaser is completely locked out. If your wasn't I wouldn't be surprised that your cam timing did not walk. Phaser cannot handle high rpms and spring pressure from aftermarket springs that are obviously required. I also said "no way" to ls7 and spent the dollars on Johnson slow bleed leak down link bar lifters. Understand that vendors all wanna have the best cam packages as far as pricing so....

[NickyRacerBoy]

6850 rpm was not the culprit.

[NickyRacerBoy]

Oh BTW I have one good head for cheap..
Doing me no good on the shelf. Hopefully will help.

[oldman]

Many cams and these exact springs go to 7000 RPM, as I 've stated I use the no lift shift at 6500 RPM on a daily basis for 2 years, and now even with cam and springs, the engine routinely see just shy of 7000 RPM...

This is a stage III max performance cam, it should clearly pull IMO upto and past 7000 RPM. The valve springs are 380 lbs just slightly lighter than the TSP spec.

I would estimate the is a 238, maybe even 242 duration cam and 380 lbs springs, don't know the lift but say it is .645... there should be NO issues at all with valve float at 6850 rpm with a normal ramp profile. My setup is a blower cam with low 22X and 62X to 63Xish lift, I pretty sure it has a conservative ramp profile and 400 to 420 lbs springs. Combo clearly capable IMO for 7000 RPM (not saying it makes power there, just saying the is lots of headroom, literally. I'll let guys with bigger cams chime in.

I don't hear a bounce off the rev limiter and these cars have a no lift shift feature where the RPM hoovers so there is no real bounce off limiter, I can hear the end of combustion which happens when the valves bend. like I said IMO, 6850 RPM and even 7000 does not kill this valve train combo.

Now I could believe and I'm 100% on board with the cam phaser sucks and anybody with cam and springs should go to a direct drive sprocket... I've moved this to a front burner on my car. This would be consistent with no shock load observed to the rear. Also consistent with a bigger more aggressive can being more sensitive to sloppy cam pashing...

[KingLT1]

These engines don't have a rev limiter like the older stuff. The throttle just closes so you don't bounce off anything...much easier on the engine that way. It was bouncing because something was mechanically wrong (obviously).

[oldman]

Originally Posted by KingLT1

These engines don't have a rev limiter like the older stuff. The throttle just closes so you don't bounce off anything...much easier on the engine that way. It was bouncing because something was mechanically wrong (obviously).

agree here.

[DatBrotato]

Originally Posted by oldman

Many cams and these exact springs go to 7000 RPM, as I 've stated I use the no lift shift at 6500 RPM on a daily basis for 2 years, and now even with cam and springs, the engine routinely see just shy of 7000 RPM...

This is a stage III max performance cam, it should clearly pull IMO upto and past 7000 RPM. The valve springs are 380 lbs just slightly lighter than the TSP spec.

I would estimate the is a 238, maybe even 242 duration cam and 380 lbs springs, don't know the lift but say it is .645... there should be NO issues at all with valve float at 6850 rpm with a normal ramp profile. My setup is a blower cam with low 22X and 62X to 63Xish lift, I pretty sure it has a conservative ramp profile and 400 to 420 lbs springs. Combo clearly capable IMO for 7000 RPM (not saying it makes power there, just saying the is lots of headroom, literally. I'll let guys with bigger cams chime in.

I don't hear a bounce off the rev limiter and these cars have a no lift shift feature where the RPM hoovers so there is no real bounce off limiter, I can hear the end of combustion which happens when the valves bend. like I said IMO, 6850 RPM and even 7000 does not kill this valve train combo.

Now I could believe and I'm 100% on board with the cam phaser sucks and anybody with cam and springs should go to a direct drive sprocket... I've moved this to a front burner on my car. This would be consistent with no shock load observed to the rear. Also consistent with a bigger more aggressive can being more sensitive to sloppy cam pashing...

They mentioned before install that they would lock out the phasers. Now whether they did or not..
specs:235/247 .657/.660 114-4
I agree it should've had no problem spinning past 7k.

Originally Posted by KingLT1

These engines don't have a rev limiter like the older stuff. The throttle just closes so you don't bounce off anything...much easier on the engine that way. It was bouncing because something was mechanically wrong (obviously).

My tuner manually set a spark cut at 6850 as well as the TB shut(as a precaution).
No lift shift was set at 6750.
In the vid it bounces off the no lift shift right before I miss shift and it free revvs, that's where the limiter kicked in.

[oldman]

yep all indication would be a phaser problem, either it fell apart, or they forgot the limiter / lockout, Vengence sells a lockout setup. I'm for a solid gear! I'm looking into the Katech one, I dropped my pan because I could not flip the chain off the front and I pinned the guide. I've been told that if I did not pin the guide, the chain does flip off the back. Definitely, you should go solid gear...

[Vtor_ZL1]

Another winner.. courtesy of street racing.

[oldman]

Originally Posted by DatBrotato

They mentioned before install that they would lock out the phasers. Now whether they did or not..
specs:235/247 .657/.660 114-4
I agree it should've had no problem spinning past 7k.
.

IMO, with that kind of lift and duration, a solid gear or complete lock out, + this would have to be clayed just to be sure and IMO, it probably is flycut time.

This is where I tell you a story cause I'm old. About 2 decades ago Honda gave the primary engine builders a B18 Type R engine, the goal was to build a max effort street engine for dyno shootout on pump gas. Literally, every builder's engine failed on the dyno. Why? Because the rod at 9000 to 10,000 RPM will stretch especially with way heavier than stock forged pistons, the .060 clearance on VTEC went to ZERO at 10,000 RPM instant failure. Like the LT1 the B engine has a hard time getting CR into the high 12s so there is enough dynamic compression to support a big cam.

[NickyRacerBoy]

Originally Posted by DatBrotato

They mentioned before install that they would lock out the phasers. Now whether they did or not..
specs:235/247 .657/.660 114-4
I agree it should've had no problem spinning past 7k.


My tuner manually set a spark cut at 6850 as well as the TB shut(as a precaution).
No lift shift was set at 6750.
In the vid it bounces off the no lift shift right before I miss shift and it free revvs, that's where the limiter kicked in.

I've been told by a calibration engineer that even though it's edited out via tuning it still has potential to move. Don't think for a second that you click a couple tales in HP tuners or whomever that there isn't the possibility that there is an unknown table working in the background. Ask your shop if it was a full lock out or just a limiter.