LS Powered Stalker

[subtlez28]

I'm excited to see we have a build section! I figured since it was my idea, I better get a build thread up post haste. I pasted in most of the content from the original thread. I tried to edit out conversation and ideas that changed. It is quite condensed here it was about a 2 year build. And admittedly, it is not up to date. I'll try to add my off season stuff soon.

My first exposure to a Lotus 7 replica was at a MCSCC track event, several years ago. The particular car I saw was a Brunton Stalker with an LS3. 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.

[subtlez28]

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.




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.





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:

[subtlez28]

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.





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.




I've been getting a bit done. I'll try to catch the thread up some.

On the oil pressure adaptor I decided to spend the money for the nice engineering and machining of the Katech piece. The part that was on there site actually would not clear an LS3 intake. However, after emailing them I found out they had just produced a new part to clear the LS3 intake w no grinding needed. It was a more costly, but the machining was clearly more intensive. I just really want to keep the build as simple, OEM, and uncluttered as possible. So an OEM sending unit hidden under the intake worked for me. I intend to use a "Can-bus" gauges. These use signals from the factory sending units via the OBDII diagnostic port (more on that later).

The Katech piece is machined beautifully and is sealed via O-ring!





Sorry, the cell phone pics really do not do it justice.

I also got the steering shaft installed which gave me the opportunity to sit in the car, turn the wheel and make engine noises! It is starting to become a car.


I took the engine off the stand and installed the LS7 flywheel with OEM bolts that came w the kit.


Put on Brunton's engine stands:

[subtlez28]

I also bolted up the CTS-V trans. I forgot to get action shots of it in the air, but I was able to wing the whole unit into place with the chassis still up on the stands!



Next I installed the new CTS rear center section (3.23 gears and G30 limited slip):


I'm working to get all the major components on hand. I am pre-assembling pretty much everything. With the engine in I could get a feel for how much wiring harness I would need.



I called up Speartech and spoke w John. After a lot of research I feel comfortable he will provide a harness what will be cleanly built to fit my simplistic (subtle) style, and have the know how to help me through any potential bump in the process. I am especially fond of his testing every harness on a real engine set up prior to ship out!

Now the hard part, waiting for him to them to get through there back log of orders so they can build mine! I probably couldn't have picked a worse time of year to order, but I really wanted the engine/trans in before pulling the trigger.

Gratuitous engine pics (that I don't think are in the thread yet):

[subtlez28]

Beyond finding parts I also got some garage time in. A friend who has been a huge help and motivator committed some hours over the weekend. We got the floor mounted Wilwood brake and clutch pedal mounted. We initially tried to mount them a little further toward the back of the car thinking it would provide more foot room, as the footwell narrows. But when I began to modify the firewall and hang the brake booster and master it was clear I had to move the pedals forward. It was basically a lot of time put in for minimal visible result, but, I'm glad to have progress toward a driving car!



The clutch pedal has a master mounted to it. Brunton makes a bracket for the Miata power booster mounting it backward and above the fire wall as the engine takes up the room where a brake MC and booster would typically go. They also provide a lever system that converts your forward brake pedal motion to backward. Space is at a premium in such a small chassis! Part of me would really like to try manual brakes, but the advise of experienced Stalker owners is to keep power brakes.

I also installed a front rotor and caliper. I took out my Percy's Wheelrite tool to make some measurements at full travel. Another area of my research lately is into track wheel/tire set up. A lot of Lotus 7 replica's run 13" race wheels. With the Wilwoods, that is a tight fit, requiring pricey custom wheels. After a discussion w a race tire distributer I was shied away from 14", 16", and 17". He explained (used) race tires are much easier to come by in 13, 15, and 18" sizes. I don't mean to come across as too cheap, but my budget is running thin, and I want to be able to afford to finish and race this beast, this year! Anyway, I am looking at probably going with a 15x10 custom steel wheel from a manufacturer who just so happens to be right here in WI! Think oval track wheels. Obviously a 15x10 steel wheel is not the lightest option, but w sticky tires, I don't think it will hold me back as much as my weigh OCD would have me think... Plus, I could always pony up for some lightweight custom alloy wheels in a year or two if I still want to.



And, yes, I know I should remove the plastic from the rotor and paper tag from the caliper prior to high speed use. LOL

Over the summer months I have made some progress. Pace has slowed to a crawl due to the increased activities of summer and my kids being home during the day, but that is far from a complaint.

When I have worked on the car it has been in short bursts, and I have neglected to take pics, which I know takes some of the fun out of the thread. We fit the seats, harnesses, pedals, and all the aluminum. We mounted the engine and took measurements needed for harness and driveshaft.

My use of the CTS-V style trans required some creativity for shifter mounting. Unlike F-body (Camaro/Firebird) style T-56s that mount the shifter right on the tail-housing of the trans, the CTS-V shifter is remote mounted, but with solid linkage.


The bad news, is with linkage at stock length, the shifter position is right were a chassis tube was (already removed in the pic). In a car Brunton built, they cut down the linkage to fit more like an F-body trans. We decided to move the chassis tube and create a mounting point to support the shifter.


The goal from the start was to trial fit most of the components, then take it apart to have the chassis powder coated. We got to that point, and I found a reasonable local powder coater. I'm proud to say I tore the car down to bare chassis in a mater of less than two hours! I was pretty excited to reach this milestone!

[subtlez28]

One week later:


We already have the front suspension back in place, and bent up some brake lines. Soon we will plumb the fuel system. I put in another nearly $1k order to Summit for car electric harness and fuel system parts, fittings etc. I think I can see light at the end of this tunnel!


We have made a small amount of progress since the last update. We installed the front suspension (again) and plumbed the brake lines:



It feels good to be permanently installing panels as apposed to the mock up stage.

I hope to make some more strides int he next couple days.

We've made some more headway, I will try to catch up.

We connected the aftermarket braided clutch lines to a factory style hydraulic throw out bearing (like an 02 Z2. Because I am using a CTS-V T-56, that came this a thicker, dual-mass flywheel, I had to space the through out bearing away from the trans. I used a piece from Katech (they are getting a lot of my $ on this build... ha). Hopefully everything works out, but I wont know for sure until I add fluid to the clutch hydraulics. I am avoiding adding any fluids now, in case things need to come apart again.


I also learned that the CTS-V T56 bell housing is longer than the F-body bell housing. We had to make room for the new hydraulic lines by nothing the CTS-V bell. This was pretty straight forward with the aluminum.


We dropped the engine and trans back in. I finally opened the box for the custom rear CV axles from the Driveshaft shop.


I opted to have some new bearings pressed into the donor Miata rear spindles. I guess that was a good choice as the shop had difficulty getting them together. My rear suspension can now go on.

[subtlez28]

I noticed the other day that the hubs really fight being turned despite the fact there is no driveshaft connected. I'm guessing that may be the new bearings... Is that normal? I can turn them, but it requires some effort! The diff itself is new, but I couldn't really turn it until the axles were installed. I may have to pull some stuff apart and investigate...

With the engine in, we bolted up a header, and made up the steering linkage. This was big for me. I can now sit in the car, shift the trans, work the pedals (except accelerator, which isn't in yet) and turn the wheels!!:driving:


I picked up a pair of front tires and had them mounted up. It is great to see a wheel and tire on the car!

I found a T-56 specialist a couple hours north of me. I decided to hand deliver the trans to avoid any risk of damage in shipping. Since I was making the trip I also brought along a F-body T-56 I scored on Craigslist. I got such a deal on it I assumed it was messed up. However, more good news there. It was good inside, and so I upgraded it with steel 3-4 shift forks, pads and billet keys. Now I have a fresh T-56 for the next project (maybe my DD 2012 Colorado w the 5.3).



We worked on the rear suspension to get a the alignment close, and the settings right to get the shock travel where I wanted it. I purchased a few sets of suspension push rods to play around with length. I found out a big mail order circle track suspension place is like 20 minutes from me (Lefthander Chassis), so that made getting the parts easy.


We bled the brakes, and clutch hydraulics. It is starting to feel like a real car! I ponied up for some pretty parts. I really did not like the factory brackets for the coils. I guess it was to speed up production but on the early LS1s (97-9 the coils mounted directly to the valve covers, which were perimeter bolt. When they went center bolt they went to brackets. Anyway, I picked up some black Holley valve covers that have the bosses to mount the coils direct. I really like how they look.

[subtlez28]

I pulled the trigger on track wheels and tires this week (its that time of year I guess).

I decided on 23x9.5x15 Hoosier Road Race Slick Radials. I am a 20 minute drive from Berget Racing Tires, so going used made sense. The ones I got are at about 80%. Thanks SCCA run off participants!



I ordered a set of 15x10 Diamond Racing Wheels. Much heavier than I would like, but I got the whole set for less than a pair of custom aluminum wheels. I figure I need to get the car on track (and almost on budget) this year. I can upgrade to lighter wheels next year.

I mentioned before about some trial and error on the driveshaft. My original stance was to use adaptors on both ends to keep the factory 3 bolt flanges on the CTS differential, and the CTS-V T-56. I figured we could use a driveshaft with a splined section in the middle to take up any movement and ease installation. I had just that kind of driveshaft on my last Jeep Rubicon project.

Well, after some lessons learned, we went with my original idea.

Here is the adaptor made for the T-56 flange:


Here is the shaft:

In other news, I received my Diamond Racing wheels. Steel 15x10s with a spun rim. I went this route based on budget. I want to get the car to the track soon. The wheels are of great quality! Obviously steel is a bit heavy, but custom aluminum can come later. The wheels are 21 pounds a piece, the Hoosier 23x9.5x15 Road Race Radials are around 19 pounds. So figure about 40 pounds per corner. Bear in mind this was measured using a bathroom scale, so it could be off a bit.


The sun is coming through the window behind the car, but here is pic of the wheels on the car:


Another catch to using steel wheels is the lack of stand off from the wheel flange surface. Diamond racing told me this would be an issue, so it was no surprise. The problem is my brake set up is stock 10" Miata rotors with beefy Wilwood 4 pot calipers. So the caliper protrudes outward of the hub face, and since the rotor is so small, it is to near the center to allow the steel wheels gradual angle away to clear. No worries though. Nothing a spacer (15mm) and longer wheel studs cannot solve.

I've been a bit neglectful of my build thread. Sadly, I am not yet racing the car, but I have made some progress of late.

One day, for inspiration I slapped on the hood and some of my magnetic racing numbers (that will be of no use to me on the fiberglass and aluminum skin).

The bad news is the classic hood, does not clear the pushrod suspension...

[subtlez28]

A racer friend of mine came up from Chicago to align the car with me. So down from the tables!

This one is fuzzy, because I took it quickly with my cell phone. He was more than a little nervous about me stepping back for a photo op at this point!

Down safe and sound, time for a fun (giant wheel-stand) photo!


Got it aligned, but... I chose the middle height points for the control arms. With the oil pan being the low point... I could not run over a 2x4 laid flat with my 23" race tires... Doh, one step forward, two steps back seems my pace...

So, I had to take the whole suspension off and go to the highest (lowest pick up points - still not very high) settings. Now I need another alignment....

I was inspired by having my number on the car, so I had the side panels vinyl wrapped and added the 228 placards and "AR" for my class (A-Race).


Then I installed the side pipes and see they are a little close for comfort to the vinyl. I bent out the passenger side as it had even less clearance. Time will tell. I'll keep a fire extinguisher handy when I start her up! May need some heat wrap. Open for suggestion here.

As you can see, we also started the wiring. Since I decided to keep the air intake on the shelf, my battery placement was compromised. I wanted it under hood to avoid extra safety equipment. The solve was to recess it into the shelf, and actually bolt it to the passenger side of the trans tunnel. I used an Odyssey battery and their aluminum box. I suggest you go direct with them, they were a pleasure to deal with and give a great direct price!
http://www.odysseybatteries.com/main...ccessories.htm
I'll get a pic of that up when I finish up the wiring.

I went with Speedhut's new CAN-bus style controls that pick up signal from the ECU, eliminating the need for extra sending units. I also ponied up for the GPS speedo. It has all kinds of cool toys like 1/4 mile times, 0-60, etc and will not be effected by differing street and track tire sizes. I chose to have the fuel gauge in the speedo. This should be cool watching one go rapidly down, while the other climbs! You can fully customize your set up. I went yellow. Hey, they look good on a Ferrari, and more importantly should be easy to see.

The blue tape was to protect the dash panel, but may have to stay. I dig the contrast!

Another friend of mine, who happens to be both a car nut and engineer has been invaluable with the electrical. Starting from scratch with just a painless T-bucket kit was a bit overwhelming.

So, as per past practice, another issue bit me. We added the radiator and struggled a lot to build hoses to fit the tight chassis. After paying for a bunch of AN stuff that would not clear, we ended up with heavy duty industrial hydraulic type stuff. The local industrial hose shop was a huge help. We filled it up with Evans water-less coolant. I come back from a few days of vacation and find some coolant on the floor. Just a couple drips mind you, but more than I would expect with all new parts... There was a pin hole near the welds on the tabs.


After I quite sobbing, I tried epoxying it. However, not wanting to take 2 steps back, I tried to do it in place with out draining the coolant. That didn't work. The coolant made it's way through the epoxy and formed a new pin hole... twice! Today we drained the coolant, wire wheeled off the epoxy (Quick Steel) and re-did it without coolant. That seems to be holding. Wish me luck!

[subtlez28]

IT LIVES!!!!!

https://www.youtube.com/watch?v=sobX..._kMmdjWGE23FAQ

Just need to tie ups some electrical stuff, fit some body work, and get it aligned!

Lets go racing!

So, bad news first. We got rained out on last Friday night, so we didn't get to run down the drag strip. Times are coming though, I promise!

That was actually ok, as I worked on the car until after midnight (before the road course) fitting the hood and tying up last minute things. I ran without the rear body work.

Good news: perfect weather on Saturday for our High Speed Autocross. As expected, even though this was literally the first time I dove it other than rolling around the parking lot, I found the confidence to push it right away! The car is obviously capable and surprisingly forgiving.

It was the third fastest car there, behind a heavily modded GTR (no real hope of catching him), and a LS swapped - well sorted and moded Datson 240Z (driven by a very skilled and experienced driver).

The form of racing I do is called High Speed Autocross. We run on ~2 mile road courses, from a stop, one lap for time (no cones).

http://www.mcscc.org/autocross.php

The car ran a 1:19.760. To put that into perspective, my fastest time with my old 02 Z-28 was 1:25.809, and I ran a 1:24.839 with a 2012 ZL-1 (580 HP Camaro).

I have some video. I will edit and put something together when time allows. Though it does not capture the excitement as it looks pretty low drama with slicks.

This thing hauled. Enough power on tap to light the tires in 4th gear meant busying myself with shifting much was not needed. It also helped me keep the rpms down for the maiden voyage (don't think I was taking it too easy though).

Going ~130 mph with no windshield was quite the rush! I know better understand the chin strap as the wind wanted to rip it off my head!

I absolutely love the manual steering! I finally understand what the car review guys mean when they say they can feel what the tire is doing through the wheel! I am strongly considering a move to manual brakes for the same reason.

As far as teething issues, there were only a couple. I discovered another pin hole in my passenger side header (at a factory weld...).

With the 23" slicks, I ran the track in 4th and 5th gear (needed 5th). I think I will move to taller slicks. Shifting into overdrive (5th) was not as speedy as the other gears. And the vague CTS-V shifter might not be helping that. Just stuff to refine.

I also started experiencing a bit of front brake lock up in fast corners (like the 130 mph one at the end of the front straight). Not so much at weight transfer. I'm used to ABS cars, but that wasn't my mistake. It happened late in the braking. The proportioning valve is already allowing full pressure to the rear, so that isn't the issue. I may try a more aggressive rear compound and taller slicks for the next event.

Long term I think I will go with race style manual brakes with split masters and a balance bar.

Another issue was temp. According to my Speedhut CAN-BUS (reading through the OBDII diagnostic port) my LS (stock 195 thermostat and water-pump) was running 210-220 moving and as much as 240 sitting still. Not sure if this is normal with the Evans waterless coolant, the gauge is off, or if the fan is just not able to keep up (puller). I may swap to a larger, pusher fan.

I'm rambling a bit. I look forward to any feedback or conversation on my results.

The right lane trap mph was not working. Lets see who can guess what number I am...

I went to a test and tune Weds with some friends.

I spent the first couple hours trying to diagnose a no-charging issue. Ultimately I gave up, charge it w jumper cables, pushed it through staging and made a run. Oddly after the run it started charging so I made a few passes.

I swapped out my 23" Hoosiers for some 25.5s. Not only do they look bad @$$, they allow me to run higher speed in fourth, avoiding using overdrive like I had to at BHF.

I ran 17 psi. I imagine it would have liked less pressure for drag racing, but really not what the tires are for. I also passed on the burn out since I am having issues with reverse...

My friend took a decent video that I will try to post soon. You can hear the poor Hoosiers begging for traction pretty much the whole way. I really couldn't go full throttle in 2nd (the gear I launch in) without burning off the tires. Third was also touchy.

I was short shifting an bit, which might explain the lower than expected trap speed.

Point being there is plenty left in it!

I also did a low speed autocross. It was in an oval track and infield, so it was pretty tight. Not ideal for such a powerful car. It also tended to push badly in low speed corners. I think this is a scrub issue, as the 15's I am running require spacers, so they are not optimal offset wise.

I also experienced front lock up again (running the 23"s).

I have one more high speed event in October. I am hoping the taller slicks help. I do not have time to do much with the brakes before then.

The off season will be the time for brake and oiling revisions.

END OF ORIGINAL THREAD

I got kind of rushed to get on the track toward the end and was less apt to photo and post details. I will try to get some documentation of the changes going now.

[iracemine]

Neat!

[heavy85]

Shaun - I've fought chronic front brake lockup issues forever. I think its too much brake torque from the big brakes. I've tried several pads but last year I tried the Hawk DTC30 front pads amd that helped a bunch. Those pads work good cold and have low torque and consistent torque across the temp range - they are actually for dirt cars. With other pads I would get similar to what you describe. My conclusion is the pads gain friction capability as they heat up and with huge front pads it takes a long time for them to heat up and when they finally do its major lock time. I found after a couple laps and the brakes are fully up to temp that gets better. Thats why the DTC30 seem to work well.

Cameron

[subtlez28]

Neat!

Thanks

Shaun - I've fought chronic front brake lockup issues forever. I think its too much brake torque from the big brakes. I've tried several pads but last year I tried the Hawk DTC30 front pads amd that helped a bunch. Those pads work good cold and have low torque and consistent torque across the temp range - they are actually for dirt cars. With other pads I would get similar to what you describe. My conclusion is the pads gain friction capability as they heat up and with huge front pads it takes a long time for them to heat up and when they finally do its major lock time. I found after a couple laps and the brakes are fully up to temp that gets better. Thats why the DTC30 seem to work well.

Cameron

Cameron

My main winter do-over is the brakes. I picked up a Wilwood pedal set up that runs two independent master cylinders, and a balance bar (I wanted to ditch the power brakes anyway). My hope is I can get it dialed in. My lock up issue is bad enough that something needs to change. It was even a problem at the low speed event I did.

While I was discussing the issue on another forum, I was pointed to a rear brake kit (for a Miata - which is what my suspension uprights are from) that uses a 4 piston Wilwood caliper. What was special about that kit is it is machined with a parking brake. This solved another issue, as I think I need a parking brake to get it road legal (inspected). The stock Miata calipers had the e-brake cable pointed right at the chassis. That wouldn't work for me. This set up runs perpendicular to the rotor, so it should work.

I'll get pics up as parts arrive.

[iracemine]

hmm. While your doing all your brake research I will pick at your brain.

If I go to a larger pad does that create more heat than a smaller pad (same rotor) or will it create less heat since I (in theory) have to push on the brake less????

[subtlez28]

hmm. While your doing all your brake research I will pick at your brain.

If I go to a larger pad does that create more heat than a smaller pad (same rotor) or will it create less heat since I (in theory) have to push on the brake less????

Hmmm. My gut says: Brakes convert forward motion into heat via friction. So slowing a car at a particular rate should make the same amount of heat. Right? If that is true, having larger components like rotors or pad should be larger heat sinks. So same heat, but less effect on the larger pad is my assumption.