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Brunton M-spec #007

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My first exposure to a Se7en replica was at a track event, several years ago. The particular car I saw was a Brunton Stalker with an LS3 (midgetracr's). The car set fast time of day. It was light, simplistic, and it was powered my my favorite breed of engine. I was racing an LS1 powered 02 Z-28 at the time (the reason for my screen name). I loved the broad power band of the LS1, but wished I didn't have to carry all the Camaro's weight around corners and into braking zones. The Stalker was a car that was less than 1/2 the weight of my Camaro (3,600 pounds w driver), easier to work on, and undeniably faster. I was smitten.


After a couple years of messing with other projects, and even dabbling in off-road Jeeps and UTVs, it was time to get back to the road course. I looked into Cobra replicas, but after digging deeper into the Stalker idea, and speaking directly with Glen, it was clear that the Stalker better fit my wants. And after speaking with Glen, I knew their new M-spec chassis was the way to go. GM LS powertrain, independent suspension at all corners, and a real roll bar that looked like it belonged there. The canti-lever suspension was a huge deal to me. Plus, it is made right here in the good old USA!:flag:


We worked out a deal and I flew down to Florida, rented a Penske truck, and met the Mineharts in person. It was great dealing directly with the owners of the company. Glen and Scott are enthusiasts, who know their stuff, and seem to enjoy sharing their product w like minded car nuts. They really made the whole purchase and pick up easy and personalized.


I got to tour the shop, and more importantly got a ride in an M-spec! A quick ride shotgun w Scott made it clear that I had made the right choice. I've had some fast cars, and have had friends w even faster cars. In fact I had just got to drive a friend's new ZL1 Camaro. This Brunton thing blew everything else out of the water! At the time their test car was running a stock, truck 5.3 liter LS engine, right down to the truck cam (though w LS1 intake and headers). My mind was struggling to comprehend what a 6.2 liter LS with say, 500 hp could do!


I couldn't wait to turn my new bare chassis into a running car to find out!!



We strapped it into the cube van, and my brother and I road tripped back to the frozen tundra of Wisconsin.



Picking it up in December meant family commitments kept me from getting started right away. Having it set idle in the clutter of the garage was difficult.


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I spent what felt like forever organizing the garage and hanging the body work up on the walls, safe and out of the way. Eventually, I was able to start fabricating some aluminum panels.


Step one, flip it over, and build the floor:




Working with the aluminum was well within the grasp of your basic, do-it-your-selfer.


The pretty bare aluminum and Clecos really made me feel like some pro race car builder. LOL


As a testament to just how light the Brunton chassis is, after building the floors, I was able to just roll the chassis over, and pick it up (one end at a time) and set it on saw horses!


Building the panels just takes patience and basic tools like a jig saw, drill, and clamps. Brunton has videos available to walk a new builder through the process, and are there to answer emails and even phone calls to help you though.


I've had a couple of friends helping me out from time to time, which really helps keep the motivation up. Just focusing on one task or panel at a time keeps you from getting overwhelmed.


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I bounced around a little and mocked up the front suspension:





The canti-levers are so well fabricated, I cannot bring myself to paint them!


But I took the rest apart and another friend (networking is key) powder-coated the control arms and spindles.


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Wow, according to the date stamp on my photo, this 6.2L L92 has been waiting patiently on a stand for almost 5 years now!! For anyone unfamiliar w the L92 it is essentially the truck version of the LS3. It has the same aluminum block and cylinder heads (though w solid rather than sodium filled valves). The L92 uses VVT (variable valve timing) via a cam phaser. It makes 403 hp in stock form w truck accessories.



Due to the cramped nature of a Se7en chassis, the VVT had to go. That extra 1/2 inch that the cam phaser took up behind the water pump was just to much. The good news is that opens up pandora's box because a cam swap is necessary. I decided to go with a stock LS9 (the ZR1 Corvette's supercharged engine) cam. It is shockingly low priced ($120) and is similar in specs to an LS7 cam. Two friends of mine are running LS7 cams in their L92 swapped muscle cars and got 420 RWHP (that should be more than 500 HP at the crank). I also picked up some Texas Speed valve springs.


Yet another friend, came up to offer his experience w internal engine work.


Here you can see the cam phaser with the timing cover removed:



Sadly, we were not able to put a cam back in. I had purchased a stock LS7 cam. But when I opened the box, it was not a GM cam, and it was damaged. So, I'm waiting on the new LS9 cam to arrive.


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We were able to swap out the valve springs.



And we swapped out the stock rod bolts for Katech ones. This is a supposed weak point of LS engines, so I figure $200 on extreme quality rod bolts is reasonable insurance.


I also installed the Corvette style oil pan (loosely) and pick up. The engine will get a Corvette harmonic balancer and water pump also to clear the chassis.

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Liking good, z! Glad to se another Brunton car on the block.


Good right up!


Thanks guys!


Xcarguy, I will be hitting you up w questions I am sure. I already have some about your seat mounting as I intend to go a similar route. But I'll gross that bridge a little later.

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Thanks guys!


Xcarguy, I will be hitting you up w questions I am sure. I already have some about your seat mounting as I intend to go a similar route. But I'll gross that bridge a little later.




Just send a pm when you want info on the seats, etc. That way, I'll be sure and get it. Sometimes, I miss the posts.


BTW, are you registered on the Stalker Gallery? The last M-Spec I see on there is chassis #006.


And . . . has Scott or Glen got you registered on the Stalker Owners Group (yahoo)?



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My powder coater dropped off some more of his work. Engine mounts, rear control arms, and the fabricated piece to mount the master cylinder (reversed):


I sent him off with the pushrods and tie rods. They are gold anodized, but I have decided to black out most parts, leaving the fasteners as is for contrast.


A friend of mine who has been a huge help dropped over today. We made some progress. It is starting to look like a car!



I also got some GM parts in. My LS9 cam, timing chain and pushrod...

I was surprised to see the timing chain was made in France of all places.


I was more surprised that ordering "PUSH RODS" at the discounted price of $15.29 netted me exactly one push rod! I thought it was too cheap to be a set of 16, but also to much to just be one. Especially considering the description label of "push rodS". Not a big deal though since I found out my L92 push rods are the same part number as the LS9s.


Hope to slap in the LS9 cam soon, and button up the engine!



To that end. Can someone advise what the substance is called that GM puts in the corner of the gaskets? It is an off white and stays tacky, sort of like plumbers' putty. Though I realize thats not what it is.

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I got a little more work in today. I finished off the top of the trans tunnel. All the clamps, lumber, and square stock are to create the slight bend in the panel as it transitions to flat:



I cut in the rough shape of the scuttle onto the fire-wall shelf, and fit the fiberglass dash to the scuttle's rear side:




We made up templates out of cardboard yesterday. That really helped making the cuts to the shelf and dash.


I completely wrapped the fiberglass dash in painters tape to avoid scratching it.


I only have a couple more pieces of aluminum to fit (the other side panel, 2 trim pieces that go under the hood, and a simple foot well panel).


Now for the fun part! Test fitting the engine and bolting up the suspension and brakes!

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  • 2 weeks later...

I was able to finish off the aluminum panels.


My LS9 cam came in. I have been asked, why use a cam intended for a forced induction engine. The reason is it is similar in specs to an LS7 cam, and I have friends who have had success w LS7 cams in L92s. The LS7 cam is more aggressive in an actual LS7 though due to its 1.8 rockers (as apposed to the 1.7s on most LS engines). Oh, and it is $120 new as apposed to around $400 for the LS7 or most any LS cam... Can anyone explain that?


LS9 cam specs: 211/230 .558/.552 (or.562 according to some internet sources...) 122.5 LSA

LS7 cam specs: 211/230 .560/.557 120 LSA

LS6 cam specs: 204/218 .551/.547 117 LSA



I purchased a VVT delete kit from Texas Speed that has an LS2 front cover, cam sprocket, and cam sensor.



I installed the oil pan w/out a gasket to align the front cover, and sprung for the GM sealant fro the corners.


Edited by subtlez28
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Nice work! Making me want to upgrade to the LSx motor myself... If only I could find a wrecked donor for nearly free, as that's what my budget for upgrades for the rest of the year will be...


I have #6. Love the new M-Spec chassis too... I switched to that style cage and love the new windshield layout it gives.

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The L92 I am building was intended for an Escalade or Denali they used to build here in Janesville.


All the power potential of the LS3 but cheaper! Though I did need the LS3 intake, oil pan, timing cover, balancer, and non-VVT cam. So it would be easier to start w a Vette LS3.

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I had to register just to see this build. I've been a avid FFR Cobra replica guy for a long time until I realized I'm too tall to fit in it. Then I found the Lotus 7 world. Out of curiosity, why did you pick this car to build? Also - did you get a standard frame or a XL frame?


This project is far better than the Corvette you had, no rust to deal with like you had on that build (my username the same on mfba too, but I still have fbody)

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With more gracious help from friends I have pulled the L92 from the stand, and bolted up the bell housing to align the oil pan. As luck would have it my torque wrench crapped out. I'm glad I didn't trust it because it wanted to put down way more than the spec 18 ft/lbs on the oil pan bolts! That would have been a bad day stripping treads out of the aluminum block! But I snugged them down so at least it is aligned, and I picked up 2 new torque wrenches the other day. A 1/2" drive to replace the failed unit and a smaller 3/8" in/lb that will be better suited for most smaller fasteners. Hope the old torque wrench was accurate when we were doing the rod bolts!! I think it was though, just the low torque settings that seem to be an issue...


Then we put it back on the stand to install the corvette balancer. I skipped the trick of heating the balancer to make installation easier. That may have been a mistake as installation was quite difficult. In fact I ruined a specialized tool made to install LS balancers. After reading a bit on the inter-webs on how much torque to apply I found it to be 250 lb/ft! So I needed a cheater bar. Problem was the special tool required a large crescent wrench (as I didn't have a large enough open end wrench). So my usual cheater pipe would not fit. After some garage scrounging, we did find a suitable replacement that did fit over the wider wrench handle:


Who knows what that super specialized, high performance cheater bar is?



I was not able to research a definitive answer on just when the balancer is on fully. This is how the balancer is in relationship to the flange now. Any input would be helpful here. Needless to say we put a lot of torque to it and even went to the old bolt method after stripping the tool (thankfully not the crank!).



In order to run the LS3 intake in reverse orientation, the oil pressure sensor at the rear of the valley cover needs to be removed. After much speculation on just how to remove the bung and machine the surface flat, I went crude and just saw-zalled and flapper wheeled it down.




Now I have yet another decision to make. Katech makes a slick piece that bolts to the flat surface I have created, putting the stock sender at a 90 degree angle. In fact they already had an adaptor for the other LS engines, but the LS3 intake allows even less room than the others. Luckily for me they just released an LS3 specific part that is even more dramatically machined. The alternative is to drill and tap the cap over the oil filter or buy a pre tapped piece.


I'm currently leaning toward ponying up for the Katech piece to keep the harness relatively stock routed, and using the cap by the filer for an aftermarket sender.

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