Rumbles SLC Build

Hi Bill glad you made it back safely. That has to a great trip. Did you take any great photos or is that strictly your wife's area of expertise?
Thanks for the you tube video tip of Zakari's build I have watched about 10 in a row. You need to travel less and build more, Ha!
See you soon.
Guy
 
I'm starting to fit my body now. I mocked up the center spider, doors, rear clam, front clam, front splitter, etc.

Exact placement of the center spider is critical because it effects everything else.

In the latest 2.2 version of the SLC Build Manual, page 68 says
"adjust the spider so that the front edges of the door openings are located just even with the front of the dash".

When I position the spider so the wheel wells are centered on the tires, there is about a 1 1/8" gap between the door opening and the chassis upright structure for the dash.

Is that what you are seeing as well?
 

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Fran Hall RCR

Moderator
This is correct Bill...you should have 1 inch +/-

You should then space the fiberglass dash panel from the aluminum cross car beam that same amount to mate the front edge of the dash with the base of the windscreen
 
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I finished my exhaust. It starts with a GM LS7 insulated header that feeds into a 4" collector and then reduces to a 3" system. I went with the Flowmaster DBX (AKA HushPower) muffler. At 6" round x 14" long, it was the largest muffler I could fit in the available space. The Flowmaster DBX case is insulated to keep engine bay temperatures down as well.

To reduce exhaust noise further, I'm also trying vortex cones. They are installed inside the 3" pipe before the muffler. The total area of the perforations in the cones are greater that the area in a 3" pipe, so Dynatech claims no power loss and 1-3Db noise reduction. The Flowmaster DBX muffler internals use this same vortex cone design.

Considering the short exhaust system, the end result is pretty quiet and has a zoomy sound.
 

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Randy V

Admin
Lifetime Supporter
Bill,

On the Vortex Cones.. About 10-12 years ago, I tried this on an SCCA American Sedan car in order to make the 100dB sound limit at one particular track. While the car did go from 103 to 98, it also refused to rev to its normal max RPM of 6800. It just flat could not breath hard at all over 6000 and would barely make it to 6200. This was with a 5 liter engine.
I ended up tossing it in the bin and installed a SuperTrap end on the pipe. It was similar in that it was restrictive, but the car could at least rev to 6800..
 
Bill,

On the Vortex Cones.. About 10-12 years ago, I tried this on an SCCA American Sedan car in order to make the 100dB sound limit at one particular track. While the car did go from 103 to 98, it also refused to rev to its normal max RPM of 6800. It just flat could not breath hard at all over 6000 and would barely make it to 6200. This was with a 5 liter engine.
I ended up tossing it in the bin and installed a SuperTrap end on the pipe. It was similar in that it was restrictive, but the car could at least rev to 6800..
This echoes my experience and research on the Vortex cones.

It's also why I was scared to try the Hushpower mufflers on my 468ci LS. The Hushpower's are by far the quietest performance muffler I've heard. They sound awesome too. The cool can feature is a nice plus and a need in our cars. I couldn't get their cfm #'s but to Hushpower's credit they did have helpful tech support. I just could never get the answer I was looking for to make me pull the trigger on them. I had already been through too many exhaust experiments to roll the dice.

I hope you have great results with them. If they do not hurt power above 650rwhp, or at least not significantly, they would be the best choice currently available for someone wanting a quiet free flowing exhaust IMHO.

I'll be first in line to buy them and start another exhaust project. They are that quiet, and sound that good IMO.
 
I got the center spider section of the body mounted. A good way to start is by installing the black plastic female alignment pin receivers. There are 4 receivers in the front clam and 4 receivers in the rear clam. To ensure the receiver fits flush into their recessed pockets, you will need to grind off the square corners on the underside.

Once the receivers are installed, the alignment pins in the front and rear clam will have a much more precise fit. First check that the factory installed alignment pins are in the correct location by examining the fit around the wheel well. The alignment pins on my body were perfect, so no adjustment was needed.

Then check the fit with your doors.

Now you can slide the entire body (front clam, spider, rear clam, doors) around on the chassis as a single unit until the wheel wells are centered on the tires, both front to rear and right to left. On my body, I slid it all the way forward until the old rear cup holder hit the firewall chassis structure. At that point there was a 7/8" gap between the chassis dash structure and the front of the door opening.

Note: Be sure the bottom edge of the front of the door opening is trimmed so it is not resting on the chassis. That can throw off your body alignment.

With the body in this position, insert shims between the firewall chassis structure and the new smaller "Shot glass holder" body mount. On my body, the center of the Shot glass holder was at the very front edge of the chassis structure. My body had sagged in the middle and required some additional shims to bring it back into shape.
 

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Bill, your Hushpower setup (without the Vortex cones) is pretty much EXACTLY what I envisioned for my own build (picked up my SLC Thursday and it's still on the trailer in my garage) but my engine is almost as powerful as Ricardo's motor, so I'm torn.

I haven't bought any mufflers yet so I'll probably be willing to spring for a pair of Hushpowers and use them on something else later if they prove to be too restrictive.

I'd like a fairly quiet exhaust but I'm not willing to attempt a setup like Ricardo's; I'm pretty sure I'd end up shooting myself before I got it finished. Maybe I'll just go with earplugs...

JR
 
The comments here about whether the HushPower (Flowmaster DBX) muffler and vortex cone are restrictive got me wondering. I did an "exhaustive" internet search on the topic this morning. I found in other forums where HushPowers and vortex cones were installed on LSx motors, Mustangs, Vipers, etc.


The consensus was:
  • Perception is that "If you can't see thru them, they are restrictive". You actually can see thru the HushPowers and vortex cones, but the perforations concern on-lookers.
  • Owners who switched to the HushPowers and vortex cones generally agreed that they are both good solutions to quiet your exhaust.
  • I found no dissenting/negative opinions from owners of LSx motors, Mustangs, Vipers who installed HushPowers and vortex cones. The owners who switched from other performance mufflers experienced no noticeable power loss. As you would expect, the owners who switched from an OEM system noticed a power gain.
I feel better now!:pepper:
 
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The comments here about whether the HushPower (Flowmaster DBX) muffler and vortex cone are restrictive got me wondering. I did an "exhaustive" internet search on the topic this morning. I found in other forums where HushPowers and vortex cones were installed on LSx motors, Mustangs, Vipers, etc.s generally agreed that they are both good solutions to quiet your exhaust. I feel better now!:pepper:
Bill, I also did a pretty thorough investigation on the Hushpower line a few years back. I had their smaller HP II's on my other smaller engined replica and they also sounded great.

I went for a 50 mile or so ride yesterday in the SLC and the Hushpower (now flowmaster) sounded good- same exhaust size as you're using but with the LS376 - 480hp crate. Just the right amount of boil with some minor popping on full throttle off situations at certain rpm's. I'm very pleased with the sound.
 
I got the front splitter mounted.

I found it easier to prop the splitter up against the front clam by wedging some scrape wood under it. That allows you to make fine movements to get the splitter in just the right place. Then reach thru the mouth in the front clam to mark the mounting holes.

I wanted to hide the front splitter supports, so I mounted them further apart on the aluminum uprights. I then cut out the bottom of the "Fangs" to hide the supports inside them.

I laid out the side splitter supports so they would not hit the front wheels when they are turned. The supports need to cut to about 19" and then treaded for the turn-buckles.

The turn-buckles are 1/4"-20, one right hand and the other is left hand thread. Most builders don't have a left hand tap, but you can use the turnbuckle itself to press the threads in. It helps if you drill out the hole first with a 7/32" bit and then use some oil.

I added 4 screws to attach the splitter to the front clam. Up front, I fabricated "L" brackets that are hidden in the "Fangs". On the sides, I hid the screws just inside the wheel well.
 

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Most builders don't have a left hand tap, but you can use the turnbuckle itself to press the threads in. It helps if you drill out the hole first with a 7/32" bit and then use some oil.

Huh, i can throw away my left hand taps! Nice idea...
 
Most builders don't have a left hand tap, but you can use the turnbuckle itself to press the threads in. It helps if you drill out the hole first with a 7/32" bit and then use some oil.
If you have a spare LH thread bolt, it only takes a few minutes to cut three lengthwise flutes with a small abrasive disc. Then taper the 'nose' a bit. It will tap very well. Your clearance hole can be standard for a 75% thread.
 
I installed the latches for the front and rear clams.

As you probably know, you need to trim the latch flange for the front clam. I plan to enlarge the side vents on the rear clam and needed to move the latches forward, so I trimmed the rear latches as well.

An accurate template is essential for cutting the hole for the latch. Once the center is cut, the screw holes are very close to the center hole and tend to breakout when drilled. I found that a Dremel tool worked better.

Once the latch is mounted, a flat carpenters pencil fits perfectly up thru the latching mechanism to mark the hole where the eyelet post will come thru the underside of the body. Once the hole is drilled in the spider, install the rear clam and use the carpenters pencil again to mark the mounting hole for the eyelet post in the clam.

With the eyelet post installed, carefully close the rear clam to see where it contacts the spider body. Then just drill the second hole and cut out the body between the two holes.

If you taper the eyelet post opening, the alignment with the latch pin will be much more forgiving.

The front is more or less the same. The biggest difference is that the clam is not hinged, and the body must be removed to access the top side of the latch mounting screws.
 

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I was installing thew headlights today.

I noticed that the glue-on fiberglass mounting flang does not align with the top headlight adjustment screw. In the attached PIC, the glue-on flange has been trimmed and is rotated as far clockwise as possible.

Any suggestions?
 

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