[Sillysspeed]

Looks good did you find a primary cat delete?

[Joshinator99]

Originally Posted by Sillysspeed

Looks good did you find a primary cat delete?

I don’t think he can delete the cat in the EU. But improving the flow into & out of the cat helps control the temps much better as well.

[SpeZ]

Since my passenger side cat melted (1/4 of its volume) and clogged alot. Pretty sure because of high zinc 5W-40 at track.
I made sure to poke a hole in each primary cat, around 1 thumb thick.
That even gained torque on high revs.
Officer, it's just worn.

[Tim M]

Unfortunately, due to sound and inspection, I'm keeping the cats. I do have concerns over degradation...seems like I can see a bit on the inlet side...hmm. Nonetheless, I pulled out the Dremel and opened up the inlet to slightly more than 2 1/4...avoiding any reversion issues - exceeding the newly ported manifold outlets.



I also spaced the O2 sensors out a bit...hardly worth the effort, but only cost a few washers.

[Tim M]

Reworked the driver's side cat...quite a bit of obstruction - some intentional and some not, it appears:

Before:



The initial inlet is over 2.25, but it necks down with the sharp tubing ends at 2 inch. So out came the Dremel.

After:



The end result is at least a smooth flow into the cat...can't open it up due to the tubing thickness. Interestingly, the Dremel provided grinding tool didn't get far. However, the Amazon grinders (for $20) did a much better job. In either case, I have metal shards everywhere...including slivers in the hands...and I was fully covered! Unfortunately, I did see more 'melting' of the driver's side cat than I was expecting...likely doesn't help the overall power numbers...

[Tim M]

Roads were clear of salt so fired up the Camaro to drive to work - no issues! Limited in work this winter, but always nice to have a project back together and mobile!



Now to schedule a tune and follow-on dyno visit!

[Tim M]

Update: currently on the 8th remote street tune from Ted Jannetty. Running quite well. Tomorrow is a dyno visit...to see if it makes more steam...anything over 700 CHP will be a plus!

[Tim M]

Success! I drove home from the heart-breaker! And picked up a bit of HP as well...

740 crank HP to be exact. Last iteration stopped the dial at 700 CHP...so x-porting the LT4 blower and porting the OEM exhaust manifolds and cats added 40 CHP! I'm happy with this result - nice ascending power curve and believe it will be sufficient for the big goal on the autobahn.

Big thanks to Ted Jannetty for supporting the dyno session and reflashes - definitely worth the effort.

Fortunately, a rather uneventful dyno video:



I will say the drive home was not without a 'hmmm'. Leaving the shop, a new noise developed...does not appear to be mechanical and may have contributed to the LTFT's split that was noticed. More to follow tomorrow!

[JANNETTYRACING]

Originally Posted by Tim M

Success! I drove home from the heart-breaker! And picked up a bit of HP as well...

740 crank HP to be exact. Last iteration stopped the dial at 700 CHP...so x-porting the LT4 blower and porting the OEM exhaust manifolds and cats added 40 CHP! I'm happy with this result - nice ascending power curve and believe it will be sufficient for the big goal on the autobahn.

Big thanks to Ted Jannetty for supporting the dyno session and reflashes - definitely worth the effort.

Fortunately, a rather uneventful dyno video:



I will say the drive home was not without a 'hmmm'. Leaving the shop, a new noise developed...does not appear to be mechanical and may have contributed to the LTFT's split that was noticed. More to follow tomorrow!

Thank you for your business Tim, always great working with you on your projects.

[Tim M]

Ted - appreciate the dyno visit support - really made the engine come alive!

Got some time in the garage...15 mins to drop the exhaust...a bit challenging solo...far easier than reinstallation, certainly.



And the culprit...appears I found the limit for self porting the tubes...little too much dremel power!:



Quite the massive leak...will see if I can have it welded closed.

Other comments...the X-ported blower may have picked up 1 psi compared to the 'Stage 1' previously. This is a bit lower than expected. The hotter dyno cell temps were significant even with the correction factor. +40 degrees F made the blower too hot to touch...

[JANNETTYRACING]

Originally Posted by Tim M

Ted - appreciate the dyno visit support - really made the engine come alive!

Got some time in the garage...15 mins to drop the exhaust...a bit challenging solo...far easier than reinstallation, certainly.

And the culprit...appears I found the limit for self porting the tubes...little too much dremel power!:

Quite the massive leak...will see if I can have it welded closed.

Other comments...the X-ported blower may have picked up 1 psi compared to the 'Stage 1' previously.* This is a bit lower than expected.* The hotter dyno cell temps were significant even with the correction factor. +40 degrees F made the blower too hot to touch...

You are welcome, on the crack, what works is you build it up with weld before porting so you don't break through.

Ted.

[Tim M]

My go to machinist/welder did it up right:



Even smoothed the interior:



New gaskets:



Solo exhaust install is a full body experience, but managed:



And we have success! I believe the tapping noise to be the mechanical high pressure fuel pump on the high lift aftermarket cam lobe (32%)...smooth idle cam is still a bit rowdy even in stealth mode (video below):

[Tim M]

A bit of closure to this thread...ultimate goal with this engine was to see how it performed on the autobahn...200 mph was the hope. Fortunately, it held together for a 34 second WOT run and topped 202!

Really impressed with this Chevrolet product with no changes to the chassis even after adding ~300 CHP.

Fun video: