Some of you may know my car or have seen it at events. I have been competing in SCCA Time Trials and some GridLife events in Street GT and Track Mod (most recently). I have been running the stock LS6 (for the most part) since I bought the car in 2020. In 2022 I added headers and an intake manifold which was all I could do within the class rules for each series. This year the car has felt slower and slower without any changes from last year. At the end of the year I was about 3-5mph down in Vmax on all the straights at Pitt Race, and about 2.5sec off my personal best there. I think 12k track miles and occasional runs past 7000rpm has made the original engine a bit tired.

For 2026 I am building an engine with the help of Summit Racing, Cometic Gaskets and Klotz lubricants. The class rules for Max 2 limit NA engine displacement to 6.4L or less. This makes an LS3 build the perfect fit. I found an L92 truck block to use as the base for the build. Then we are going to fill it with the full line of Summit Pro LS parts (crank, rods, pistons, cam, etc)! I will be documenting the process in here with all the parts used. Our goal is to make 550 wheel hp on pump 93 octane. The basic outline will include around 11.5:1 compression, TrickFlow 280 heads, short runner intake and a cam and valvetrain capable of around a 7500rpm redline.

So far all I have is the block. Since the L92 is a truck engine with DoD/AFM, I had to plug the towers in the block the oil flow. I tapped the holes for a 3/8-24 set screw vs the hammer in plugs or rivet type kits. I used the BTR plug kit in my Gen V truck AFM delete, but I like the more mechanical retention of threads for this engine.

Next, I dropped the block off at Cragon Automotive, a shop around here that does a lot of Chevy and Corvette work. They are going to clean it up, line hone, bore, deck etc. Stay tuned for more updates as the progress moves!

https://cragonautomotive.com/

 

Look forward to seeing your progress! Good Luck!

 

Are you going to keep the stock PCM? Or make the move to aftermarket standalone?

Convert to 24x reluctor?

This is going to be a fun one. I think many of us have been following the journey of this car for years.

 

Where did you find the block? Junkyard score?

I'm following your build, as I have a very similar one myself, albeit iron block. No dyno yet, but I am hoping after the BTR Trinity install I am also in the mid 500s

408ci
11.3:1
TSP Brawler Series LS3 heads (stainless valves)
Johnson linkbars
Sum 8721R1 cam
90mm TB
1 7/8 headers, 3" x-pipe, z06 Ti's

I wanted 7500rpm, but I am settling for 7200 and shifting at 7. I've seen a few 4.8 crank/rod combos in 6.2 blocks- that might be an engine I go for when then this one pops, because rpm is fun

 

help as in sponsors? nice.

 

Keeping the stock PCM and going with a 24x wheel crank. Summit has both 24 and 56 available in a forged crank but I dont want to mess with converter boxes and I dont have the budget for a Halltech or something stand alone.


I found the block on FB marketplace. It came with a Camaro the guy bought but wanted to keep his car old school with a big block. I dont know the history or anything about it, but the bores are still stock and looks like it will clean up well.

Yes, pretty close! RPM is definitely fun! I am going with the larger heads, short runner intake, and SUM-8744R1 cam to make this more of a top end engine. Since we are "displacement limited", allowing the engine to spin more will make more power up top. For road course use, it will just shift the powerband up. Using the short runner intake will sacrifice some torque down low, but in the 200tw tire classes its already difficult to dig out of the slow corners with less traction. Even the big cube cars like Ryan Matthews and Justin Peachey are using short runner intakes.

 

Yup! Not everyone has $25k+ to have HPR, BTR, Lingenfelter, Katech etc to build them an engine. The idea here is to show what power and reliability even the more budget friendly options have.

 

Awesome.

Two things.

Do you have a CCW crank on tap? My knowledge comes from YellowBullet and Bret which suggests more miles and seasons between rebuilds as well as better rpm capacity.

Second thing: Haltech Rebel LS is basically an R3 at half price or less which also includes a harness. $1400 I think at my last check around black Friday? One hell of a deal.

The only differences between R3 and Rebel were related to boost functions. I have an excel sheet somewhere on it.

 

No CCW crank. My limited knowledge suggests that more for stroker combinations. I need the stock stroke to keep under the 6.4L requirement.

While the rebel is a good deal at $1500, its about $1499 more than I have extra in this build budget, lol.

 

Amen! Yes. I've not had a budget limit until the baby came along. That Z06 is basically going to be pushrods, oil lines and incidentals to get it running now. And whatever I can sneak into it of course! The coupe is much more firmly budgeted mostly because it is the red headed step child.

Your point on the ccws. That is why the 402 is what it is. I could not at the time find a CCW with a factory stroke which was not also a $5k custom order.

 

I have a 6.0 with 4.8 crank and basically 4.8 rods(6.250 vs. 6.275) with custom forged Wiseco pistons, LS3 heads, intake manifold, custom Cam-motion cam, BTR platinum springs, BTR shaft mount rockers, Johnson 2126 lifters, etc... going in my road course car. It will be safe to rev to 7500-8000 but it wont make power up there on an OEM LS3 intake manifold so I wont likely shift it that high. Gotta watch alternator RPM up that high also... 10% under drive ATI + 3" Motion alternator pulley should keep it in check.

HPR built my short block. I think my total bill with them was shy of 5500. I supplied block, crank, main and head studs. Bought rods and pistons from them plus all machine work, bearings, etc... They also inspected, CC'd and skimmed my heads. They can do work that doesnt cost 25-50k dollars... but yea their big cube motor is like 55k... bonkers.

 

I was going to use Summit reciprocating parts, but last time I checked they didn't sell balanced assemblies and all of the machine shops here in NASCAR country want to charge $20k just to balance and fit pistons.

I think an :LS2 valley cover will seal the DOD crap, but plugging certainly doesn't hurt.


Good luck

 

That's hilarious!

 

Are you restricted to use the stock PCM? Im considering a motec M190

I have a CCW crank in mine, HPR recommended it do to LS cranks flexing a bit in the center when making power on a stroker. Bearings live longer

 

There is so much to learn in this world, damn. I was really happy with my parts choice for this 408, but you guys were talking about CCW cranks, and now Im sad I didn't spend more money on my bottom end

 

Then this will make you even sicker, my Callies CCW crank was only about $200 more than a none CCW crank. Also went with a callies billet reluctor wheel, was $50 more than than the GM 24 tooth

 

I did the billet wheel too, because I've had issues with the GM one bending before

but I didn't even know about the CCW crank at the time

welp, maybe next motor build I'll get it right!

 

Oh wow. @davidfarmer is still active in the forum. I had no idea. I remember 20+ years ago getting down into the paddocks and hanging out when you were running the yellow C5 Z06 at Lime Rock one summer after the oily Skip Barber cars had wet down the starting grid. Pretty sure I was paying more attention to the flag girls than anything.

Re: capping the oil lines on a newer block for DOD... I have a National A-37 bearing sitting on a shelf at home. They're $15 on Amazon and if you break it apart the rollers are apparently the PERFECT size to block GM oil passages in the galley intended for DOD. Just tap them in with a copper hammer.

 

Thanks David! The shop doing the machine work can balance it no problem. I think they quoted like $300 or something along those lines. I dont remember the break down, but the total cost of machine work and balance was around $1500.

Something about relying on those little o rings on the Ls2 cover didnt sit right with me on a race engine. Im sure its prefectly fine, but I like the mechanical interlock, lol.


Cost is main driver for the stock PCM and non CCW crank. I am using all Summit brand components, and they dont make a CCW crank.

This is what will be going in:
https://www.summitracing.com/parts/SUM-180LS362224

The Summit crank is forged and lightened, and just a few bucks more than a stock cast LS3 crank. I am not concerned using this in the build for a couple reasons. Keeping it stock stroke, there will be less of a moment pushing on the crank than a stroker, and with "only" 11.5:1 compression the cylinder pressure is still lower than a boost application. Being forged its already a stronger material than stock too. But keeping an eye on the bearings like you mentioned is a good idea after each race season.

 

Yes, yes I must have exactly the same problem with my car! Its only seen 25 years of track events 13 of which its been cam'd. I'm 2 sec off my pace and just don't seem to be able to get it back. I was blaming it on me now being >60 yrs old. I like your excuse reason better! Lol!

Good luck with the build, can't wait to see the results!

Rob