LS1 Based Engine Tech LS1 / LS6 / LS2 / LS3 / LS7 Engine Tech

500whp LS3 swap build!

Old 07-02-2019, 11:43 AM
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500whp LS3 swap build!

Hi guys! I’m pretty sure nobody’s in here, but maybe I can attract some attention.

Back in October 2017, I took my 2002 Z28 to a track day at Gingerman Raceway. It was my first time on track with my new suspension (Strano SP141 springs, Koni SAs, BMR swaybars, plus a UMI adjustable torque arm). Had an awesome time and set a new personal best lap time of 1:36.57 seconds. I still had a ton of room to improve.

Anyway, after six sessions, most people had gone home and they did an Open Track session, where anyone from any run group can go out at once. My friend Conan was there in his 2005 Porsche 911 and had been running in the Advanced run group while I ran in Intermediate, but for this session we were both out at the same time. Conan is an extremely skilled driver, and his car is (obviously) more capable than mine. We’re a close match in the straights, but his brakes (14” StopTechs all around) are way better than mine (13” Baers in front, stock rear), his tires are better, his handling balance is better, etc. So anyway, I started the session a few cars ahead of him, and it took him until the end of my second lap to get past the traffic and catch me. I pointed him by, knowing that the alternative was to have him on my *** for the entire lap. I decided I’d rather chase him. So I did that for a lap, trying to follow his line to the best of my ability. I had been maxing out at about 127mph on the straight, and on the next lap, I decided to see if I could touch 130mph. I chickened out at 129mph and braked, and was too late anyway. I locked them up and spun into the gravel pit.

(Conan first appears at 3:18, and **** hits the fan at 5:20. In the video, I’m being followed by a coworker in his 2016 Camaro SS; his footage is on top in the video.)

I restarted the engine and discover that the exhaust is now 10x louder. Fun! You can hear me rev it a little at the end of the video (~5:45). Turns out the exhaust broke on the driver side at the flange where the manifold connects to the converter pipe.


I have a strict policy of not replacing broken factory parts with more factory parts, and that meant it was finally time for headers! I also believe strongly in paying good money to get quality stuff with minimal compromises, and for me that meant Kooks longtubes. The engine has 120,000 miles on it, so I figured it would be a good time to do spark plugs and wires too. It’s gotta be easier with the manifolds out, right?

So anyway, Kooks longtubes are expensive, and I had recently learned that my wife was pregnant with our second child, due in July 2018. I determined that, budget wise, this project needed to wait. So I parked the car and started making plans. Since the car would need a tune, I decided I wanted to do a few other things to get the most bang for my tuning buck. That meant a camshaft and upgraded valvetrain, and a bunch of other stuff. I also decided it was time for a tubular K-member, and so rather than do those upgrades in place, my plan was to drop the engine, perform the upgrades while it was out of the car, and then put it all back in together.

Time passed and I continued detailing my plans. I ended up calling Sam Strano during his 2018 Black Friday sale and got a great deal on the following:

Kooks LTs and catted Y
UMI road-race K-member
NGK plugs and Magnecor wires
UMI adjustable rear LCAs
All new Moog front suspension bushings
Strano swaybars (I don’t like the balance with the BMRs; too tail-happy. Strano’s rear bar isn’t as stiff.)

I hadn’t yet decided on exactly what to do for cam and valvetrain, so I waited on those items. Fast forward to Spring 2019. My annual bonus from work comes, and I get the go-ahead from my wife to spend it any way I want on the car.

I start shopping around. I’ve got a cart of stuff at briantooleyracing.com all set to go — their Stage 3 cam, trunnion upgrades, timing set, lifters, ATI underdrive Superdamper, various ARP bolts, Bosch 42# injectors, and poly engine mounts. Then from a few other places, I had pushrods, conical valvesprings, a ported LS6 oil pump, a fuel pump, a windage tray, and a crank scraper. The total was a bit under $3500, which was right at my budget. I was disappointed because I had wanted to throw a TurnOne power steering pump on the list.

Anyway, I’m like a day from pulling the trigger on all that when Facebook Marketplace shows me an LS2 with 40k miles on it, fully disassembled, for $4k. I’d be able to buy that, still throw most of those upgrades at it during reassembly, and then sell my LS1 and the LS2 takeout parts for most of the difference in cost. I contact the guy and start going over details. A couple days go by, and I’m close to pulling the trigger on that, when FB Marketplace shows me an LS3 for $3500. It was listed as “longblock or complete engine.” I contact the seller and ask if the price changes for the complete engine. It does — he wants $4500 for it complete. I’m still interested. We start talking, and it turns out he’s an engineer at Katech (i.e. knows his **** and has access to some really great resources), and he offers to do some upgrades to the LS3 for me before I come get it.

To be clear: this is not a Katech engine. It’s an engine a Katech employee removed from his own car and then modified after-hours, using resources available to him in his position at Katech.

Last edited by JakeRobb; 07-02-2019 at 12:41 PM.
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Old 07-02-2019, 12:27 PM
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Re: 500whp LS3 swap build!

Long story short, there is now an LS3 in my garage, upgraded with the following:
Custom cam — basically Katech’s Torquer LS3 cam, but updated with a more modern lobe design. Specs are 226/239 605/621 113+4
PSI 1511 valvesprings
Trend 3/8" 0.080 wall pushrods
Katech locators
LS7 lifters
Blue Viton valve seals
Katech C5R timing chain
ARP cam bolts
LS2 solid tensioner
CHE trunnion bushings
24x reluctor wheel pressed on the crankshaft
CNC-ported heads
Katech billet tensioner
ATI super damper 10% underdrive
ARP balancer bolt
ARP rod bolts
Katech oil pump
Improved Racing crank scraper and oil pan baffle
Block steam-cleaned
Crank journals polished

The cam was verified with Cam Doctor to within 1/2į of spec, and then the valvetrain was tested on a Spintron as stable to 7600rpm. I plan to spin the engine to 6600; I’m told that the factory LS3 rods and pistons are a liability above that point.
















Last edited by JakeRobb; 07-02-2019 at 12:46 PM.
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Old 07-02-2019, 12:37 PM
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Re: 500whp LS3 swap build!














Last edited by JakeRobb; 07-02-2019 at 12:46 PM.
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Old 07-02-2019, 12:39 PM
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Re: 500whp LS3 swap build!

In addition, I have the stuff I bought last year from Strano, plus the following:
Speed Engineering 92mm throttle body
Racetronix fuel pump + hotwire kit
Energy Suspension poly motor mounts
ARP header studs
Truck starter

All of this came in at slightly less than my original budget (after I sell the LS1), such that I could afford the TurnOne PS pump with billet pulley after all.

I’ll be transferring over my ACT forged steel flywheel (15lbs), McLeod RST clutch, and built T56, plus my stock AC, water pump, and alternator.

The unmodified Torquer LS3 cam with upgraded springs and pushrods typically makes 525bhp on an otherwise stock LS3 with headers. With the updated lobe design, the crank scraper, the ported oil pump, the underdrive, the more efficient PS pump with lighter pulley, I’m hoping for maybe ~560bhp, which should work out to nearly 500rwhp. I’m trying to be conservative with those numbers; maybe I’ll break 500 at the wheels!

As of now, the LS1 is almost completely disconnected and should be ready to drop as soon as I get some more time to work on it.

Follow this thread for photos as I make progress, plus numbers and videos when I get it tuned, dyno’d, and back to the track!
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Old 07-02-2019, 12:50 PM
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Re: 500whp LS3 swap build!

Rewinding a bit:

Before that October 2017 track day, I installed the UMI torque arm. While removing the factory arm, I broke a bolt off in the trans tailshaft.



Despite my best efforts (welding a nut on it, etc), I was not able to get the broken bolt out. I finagled something good enough for the day and moved on.

When the engine+trans is out, I’ll be able to drill out that bolt and restore sanity.
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Old 07-02-2019, 12:52 PM
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Re: 500whp LS3 swap build!

I will also be replacing my PS rack with a replacement from Rack Doctor. The old one has a slow fluid leak. I was quoted $900 a while back by my favorite mechanic to fix it; I passed, knowing that it’d be massively easier for me to do myself when I had the engine out.



I’ll have some cleanup to do as well.
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Old 07-02-2019, 12:55 PM
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Re: 500whp LS3 swap build!

While I waited for the LS3 to be completed, I got started on removal. I am doing the work in a garage with pretty low ceilings, so step 1 was removing the hood. No way I could get the body up high enough without doing this first.

To keep it out of the way, I got a pair of 50lb-capacity bicycle hoists, built a little frame out of 2x4s, and lifted the whole thing up to the ceiling:



Before I put it up, though, I took the opportunity to weigh the stock 2002 Z28 hood. It is 51.7lbs, including latches and struts, but not including hinges.

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Old 07-02-2019, 12:59 PM
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Re: 500whp LS3 swap build!

I bought a new F-body oil pan, because I want to leave the stock oil pan with the LS1 to make it easier to sell.


It came with a factory baffle preinstalled. I removed it.


The factory baffle weighs 2lbs 15oz.


The Improved Racing baffle weighs 1lb 2oz. Almost two pounds saved!


The Improved Racing baffle, installed:
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Old 07-02-2019, 01:05 PM
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Re: 500whp LS3 swap build!

By this time, the seller had the LS3 ready to go. Off to get it!

I brought the oil pan with upgraded baffle with me. We installed the crank scraper (pictured earlier) and bolted up the oil pan and pickup with extra hold-down brace.



The seller showed me the Spintron data from my valvetrain test, indicating that it’s fully stable to 7600rpm. I wasn’t allowed to take pictures of the graphs or anything, but it was impressively stable.

Then it was time to load up:



It’s home!


Later that evening, I rolled out the engine hoist and lifted it out of the truck.



And finally, into the garage and transferred to the engine stand.

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Old 07-02-2019, 01:41 PM
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Re: 500whp LS3 swap build!

This is out of order, but here’s the LS3 right after coming out of its donor car, a 2014 SS 1LE.

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Old 07-06-2019, 02:51 AM
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Re: 500whp LS3 swap build!

Progress update:

I finished disconnecting things today and began the process of lifting the body off the subframe. In the process, of course, I found a few final things to disconnect.

With the engine hoist chained and strapped to the body, I lifted it up off of my jack stands and slid them clear:





Then I lowered the car until the engine and trans touched the sled I had prepared (a 1000lb Harbor Freight furniture dolly with some screwed-together 2x12 lumber on top to distribute the load):





Then, I unbolted the six 18mm bolts that hold the subframe to the body and began lifting, stopping every inch or two to make sure I hadnít missed anything and that nothing was getting hung up and causing issues.

I had it almost completely out when I had to call it quits for the day:




So I slid my jack stands back in place, extended them to hold the body, and washed up. Iím not using any cribbing blocks ó my large jack stands are sufficient on their own, with just a single piece of 2x4 between the tops and the body.

Tomorrow, I'íll lift it the rest of the way, roll the engine clear, and begin the process of transferring accessories to the new engine.

Last edited by JakeRobb; 07-06-2019 at 09:47 AM.
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Old 07-08-2019, 12:25 PM
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Re: 500whp LS3 swap build!

Itís out! Iíve made a bit of progress moving things over and installing new parts, but there is a lot more to do.

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Old 07-10-2019, 01:06 AM
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Re: 500whp LS3 swap build!

Were you pretty much stock LS1 in the engine department? If so, a 500whp LS3 is going to make those track days much more exciting! =)

I think you made the right choice on the headers. I've extremely happy with my Kooks headers. I think I've had mine since around 2011. The fitment on them is second to none.
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Old 07-10-2019, 09:59 PM
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Re: 500whp LS3 swap build!

Yes, stock with a lid+K&N and a Corsa catback; dyno'd at 325/343. Since then I've added a lightweight flywheel, but also gone up to a 17x9" wheel from the stock 16x8s. Nothing else that would influence RWHP, but lots in the turning and stopping department.

I picked Kooks after a conversation with Sam Strano. In his experience, they tuck up tightest to the body. I'm lowered close to 2" on Strano springs, so retaining as much as possible of what little ground clearance I have left is among my highest priorities.
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Old 07-11-2019, 10:49 AM
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Re: 500whp LS3 swap build!

Excellent documentation of an interesting project. Makes me wish I was 40 years younger and could do something similar. The LSx platform is amazing. Instead, I'm working on a deal to sell my Formula. All it's doing now is collecting dust in the garage. Going to be interesting to see where this site is going. You and I are the only moderators left that actually do anything, like helping people.
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