What would you hypothetically build? Now with more CTS-V

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Long time no update.  Back in the spring when the lockdown started, I got bored, so I tore into my car.  Because I can't leave a good thing alone.

I ported the blower more.  A lot more. 








I also bought a lid spacer.


I did more work in the lid.



I knew it would need more fuel, so I stepped up to ID1300 injectors.  If you read back through, this is my 3rd set of injectors.

I also finally replaced the fist part I put on the car.  The airaid intake was swapped out for a DDP.



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We moved in June and I hadn't touched the car in a few months.  It needed maf tuning and I just couldn't get motivated to get it done until last weekend. 

I went to the hill last night. Typically I can cut 1.4x 60's with the occasional spin later at night once the dew settles in. Last night was awfull.  I spun no matter what.  I doubt they put down any glue.

First pass was a test to get a datalog. I had tuned all of the maf curve up to 9000hz on the street and wanted to do the rest at the track. The car spun instantly off the line and I pedalled it. When I pedal, it usually upshifts to 2nd or 3rd. So it didn't recover well.
60' 1.907, 7.32@103.7

The tune was close, I had to pull 8% across the board in the maf curve above 9k hz. The car runs great with the new DDP intake and a dialed in maf curve (+- 1.5% error). Map was 207kpa in 2800'
DA. I would typically see 201-203 in similar air last year. And g/cyl moved up enough to get me into my safe timing area and only had 20* total. I had some pulled for safety anyway, so I added 2* back in.

Next pass, spun and pedaled again. 1.72 60', 6.89@108.4. A/F was ~1% rich and timing was 23*. In 2800' air I would typically run 107mph on a perfect pass (6.4-6.5 with 1.4x 60'). So with a bad pedaling pass running more mph is a good sign.

Last pass 1.87, 7.15 @107. I left off idle and this was the worst spin of the night.

Overall, the tune is pretty good now. I'll work on adding timing once the weather improves. I'm going to have to go to a better track to get the car to hook. I think there are some 6.2, maybe 6.1's in there doing some ricer math on my 160+ pass spreadsheet.

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Yeah I saw your 7.15 pass crazy.  They sprayed before every elimination round as I was first in line each round and saw/heard it on my tires but it was minimal at best.  I hooked great out there last season in the Shelby and this season I spun my ass off every pass but one...the one I chunked the rear on.  Frustrating to say the least.  Some cars are getting down it just fine but I wasnt thats for sure.


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It's done and I've been driving it to work to break it in.

I had been gathering parts to rebuild my shortblock for a couple years, but since it was fine it was hard to justify tearing it apart.


A coworker had been interested in purchasing my complete motor for a while, so once I knew he was serious I started looking to build a new motor.  I already had 4.070 bore stock stroke pistons, so I had to stick with that.  I found an aluminum gen 4 5.3 block.  Back in February, I took it to Shackletts to have it re-sleeved with Darton sleeves cut to 4.070, and line honed for new ARP main studs.



Old motor was sold from valve covers to oil pan as I bought all that stuff new.  The only things I re-used on the new motor were the cam and balancer.



Shacklett finished the block in mid July.




I have an "office" in my basement that is air conditioned and cleaner than the garage, so I covered the carpet with cardboard and assembled the shortblock in there.  I used a new stock LSA crank, A mix of standard and +.001" Clevite H series main bearings to get .0024-.0026" main bearing clearance.


I used Callies Ultra I-beam rods and Clevite bearings to get .0025" rod bearing clearance.


The rings were fit to .0026" top and .0028" second.


Then I pulled it all back apart for deburring, cleaning etc.

Matched the oil feed holes to the bearings.


Deburred all the casting flash to help with oil drain back.


And drilled and tapped the afm towers



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Then I cleaned it all up and assembled it.




Degreed the cam



The heads are Brodix BR3's ported by LME with inconel exhaust valves, chamber softening and I had them cut off the 6 bolt tabs because "stock block for life".




Since this block doesn't use oil squirters, I moved down to a melling 10296 pump that I ported.



I put an improved racing baffle in a used stock oil pan.


I used BTR's new shaft mount rocker system with their new rockers on the exhaust and new LS3 rockers on the intake.



I bolted the heads down with ARP CA625 studs and LS9 gaskets.  At this point I ordered custom length Manton 11/32 pushrods because I'm using Johnson 2110 lifters.


Slung it in the car.


And last Tuesday night I fired it up.


I'm going to drive it a couple weeks and cut the filter open to be sure nothing is wrong.  Then I'm putting my 15" wheels and brakes on, rebuild the diff and do some preventative stuff to the fuel system.



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To sum up that engine build.

377 cubic inches (6.2L)

Gen IV aluminum 5.3 block with Darton dry sleeves with a 4.070" bore

New GM LSA crank

Wiseco 11 CC dish pistons with upgraded thick wall S718 pins, 9.5:1 compression assembled

Callies Ultra H beam rods

Clevite H series main and rod bearings

ARP mains

LME CNC Brodix BR3 heads, hollow stem stainless intake, inconel exhaust

ARP CA 625 head studs

GP tuning 2.5 cam

Johnson 2110 lifters

Manton 11/32" pushrods

LS9 head gaskets

BTR shaft mount rockers


I figure the shortblock is good for 1300hp.  I'm sure I'll be there one day.  Right now I'm guessing it will make 800rwhp and hopefully run 6.0x and maybe 5.9x in perfect weather.


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Wow.   Nice stuff.

I've been watching a few head porting vids (by Eric Weingartner) where I just saw some "chamber softening" last week.   What benefits do you want from that?

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It should allow me to run more timing on 93.  I thought the compression was going to be closer to 10:1, but the machine shop didn't deck the block as much as I thought.  It may not help as much on 9.5:1, but it should help regardless.  

I think it's usually used more with flat top pistons and higher compression.  Basically it gets rid of all the quench area and funnels the charge to the center of the chamber as the piston hits tdc.

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There are SO many considerations/variables in head flow/cylinder pressure/spark timing.   It would be so neat to see that engine perform with and without "softening" to see the results on paper.

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So let me ask... :yes: 

What was the advantages of selling off the 6.2 LSA for a aluminum Gen IV 5.3 shortblock?

I'm guessing strength with the ARP hardware and Darton sleeves, but how did the cost work out on that?

Break even or cost more (my guess is more cost)? 

I need to start planning for a forged bottom end myself because my D1X can make more power than my bottom end can handle, and I'd like to turn it up some more. :yum: 

With no more MARTA testing, it's a green light on going more racecar. :hyper: 


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The biggest advantage to selling the LSA motor was $6500 in my pocket for a complete running longblock.  Otherwise I would have used the block and crank, sold the heads and thrown the rest away.

The second advantage to the 5.3 block is more meat around the mains and the darton sleeves (6.2 sleeves are very thin and some crack at low power).  Total including the block, sleeves and machining, the block cost me about $3500.

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This wasn't some big master plan kinda build.  It's just how it all came together.  If I hadn't had someone wanting to buy the LSA, I probably would have just built that block or possibly sleeved it.

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Thanks for the info!

So the 5.3 has more meat In the mains. Who’d thought! I’ll definitely look in to the sleeves as well. 

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On 8/30/2021 at 9:50 AM, Mike said:

.  Basically it gets rid of all the quench area and funnels the charge to the center of the chamber as the piston hits tdc.

Hmmmm....a long time ago, possibly when I was in automotive school, I think I learned that there was quench, squish, and squench in a chamber.  The internets seem to lump quench and squish together...except for https://www.crankshaftcoalition.com/wiki/Quench

My terms:  quench is the area of the chamber exposed to coolant.  Squish is the area (mostly in a wedge head) that is "pinched" by the piston gettng very close to the chamber.  Squench is an area of both squish and quench.

Has anyone heard that?

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I'm almost finished with the fuel system, rear suspension rebuild, control arm modification and Carlyle brakes for the 15" wheel conversion.  I wire brushed, sand blasted and painted all the steel parts to remove the minor rust from northern VA winters.  I'll put the new struts up front this weekend and bleed the brakes.  Maybe I'll get to go to the track Tuesday night to start refining the tune on the new motor.

fuel pump.jpg.

control arm 1.jpg






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