Rumbles SLC Build

[Mesa]

What cable tuning with the Ricardo? My experience was that it worked perfectly right out of the box, with the worst being that shifting out of 5/6 don't cause the shift lever to automatically return to centering over 3/4 because of lack of a return spring.

Not to side track the thread but, I needed custom length cables for my build due to custom routing. Also I have the GT Shifter not the Brandwood shifter and in my case and a few others - the inner cable length was too sort and thus required an extender on the threaded end section at the trans. In the end I am not sure he could have done anything about the 'short coming' and I moved the stop mount on the shift base closer to the shifter to compensate. I also have the exact same 'lack of return to center' issue you mention. Contact me directly to discuss further.

 

[Ben]

Bill, I'm really glad that you are spearheading the shifter issue. I was going to send the rear case cover to Jim so he could use it as a template, but try as I might, I can't remove it. Whatever was used as a gasket sealant has proved to be stronger than I.

To complicate the issue, I can't remove the rear clam because the center spider is suspended from the garage door rails, thus the garage door can't be opened. This forces me to work from within the engine bay. Taking down the spider would be a ton of work, and I'm still not guaranteed to get the case off.

Rob: I found the same thing with fore/aft adjustment. I still don't like the position of the telescoping motor as it can potentially get in the way of my left foot. I too had thought about removing both motors and fabricating some sort of hand crank mechanism.

 

[Vidal]

I tried a modification to the prototype bracket to reduce the side force on the shift rod. I tack welded the fore/aft cable bracket at the 11:00 position. That angle seems to work better.

While your experimenting, may I suggest adding a flange to your bracket that moves that cable mounting point forward? This will decrease the angle and force required.

 

[Bill]

I think its time to show what's happening at the "Rumbles Skunk-Works". Sometimes a simple phrase can change everything. For me, that phrase was "I want a trunk".

The area in front of the cabin was filled with cooling system radiator, reservoirs, lift pump, etc. There is quite a bit of space up front for a trunk, but that moves many vital component to other places.

The most significant move is the radiator. I moved that radiator to just behind the passenger. I expect very little air flow back there, so I enlisted the help of a expert with lots of experience building cooling systems for rock crawlers. Rock crawlers use lots of horsepower to scramble up impossible mountain faces, but they do it at a very slow speed (i.e. no ram air flow). Due to the low ram air flow in the rear, the radiator is considerably larger than the RCR unit. Its a high tech piece with a 2 pass layout, 3 row core, and narrow passageways to maximize cooling. We then added the most powerful fans that SPAL makes. Due to the confined space, there is 1 pusher and 1 puller fan. It all fits within the SLC body with just a fraction of an inch on several sides.

I've also mocked up the radiator hose, heater hoses, steam lines and a custom expansion tank.

You may remember quite a while back I decided to mount the fuel tank as far forward as possible. The reason was that the radiator fits flush to the frame, so there is no room to route the heater/AC lines forward to the cabin. Moving the fuel tank forward allows just enough room to route the hoses between the tank and the vertical chassis member.

The custom expansion tank is meant to flow with the lines on the intake manifold, and clean up the firewall. It also hides the steam line coming from the motor as well as the pulley system. The fill neck is a bit hard to get to, so it may not make it to the finished car.

 

[Ian]

I think its time to show what's happening at the "Rumbles Skunk-Works". Sometimes a simple phrase can change everything. For me, that phrase was "I want a trunk".

The area in front of the cabin was filled with cooling system radiator, reservoirs, lift pump, etc. There is quite a bit of space up front for a trunk, but that moves many vital component to other places.

The most significant move is the radiator. I moved that radiator to just behind the passenger. I expect very little air flow back there, so I enlisted the help of a expert with lots of experience building cooling systems for rock crawlers. Rock crawlers use lots of horsepower to scramble up impossible mountain faces, but they do it at a very slow speed (i.e. no ram air flow). Due to the low ram air flow in the rear, the radiator is considerably larger than the RCR unit. Its a high tech piece with a 2 pass layout, 3 row core, and narrow passageways to maximize cooling. We then added the most powerful fans that SPAL makes. Due to the confined space, there is 1 pusher and 1 puller fan. It all fits within the SLC body with just a fraction of an inch on several sides.

I've also mocked up the radiator hose, heater hoses, steam lines and a custom expansion tank.

You may remember quite a while back I decided to mount the fuel tank as far forward as possible. The reason was that the radiator fits flush to the frame, so there is no room to route the heater/AC lines forward to the cabin. Moving the fuel tank forward allows just enough room to route the hoses between the tank and the vertical chassis member.

The custom expansion tank is meant to flow with the lines on the intake manifold, and clean up the firewall. It also hides the steam line coming from the motor as well as the pulley system. The fill neck is a bit hard to get to, so it may not make it to the finished car.

Ferrari F348/F355 is set up similar to the way you propose. Pretty cool idea!

 

[Jack]

Hey Bill, you're ight up there with Rob Mesa on out-of-the-box solutions!
Very interesting, indeed.

 

[Will Campbell]

Wow.

Which way does the air flow through the rad? I imagine that pumping pressure from the tires would tend to force the air through the outside to the inside- is that what you have planned? Or are you planning to use wheelwells to mitigate that?

So now there will another SLC with a trunk in the front.

Cool!

 

[Dave Lindemann]

Bill - Nice work, very innovative - way to think out of the box!

Dave L

 

[Bill]

Before I started, I probed Fran about the aerodynamic testing he had done and how the air flows through the engine bay. Fran tells me it should flow from the outside to the inside.

 

[Ricardo Montalvo]

Very innovative. I'm looking forward to see how this comes out. I've always been envious of Mesa's trunk...

I didn't phrase that properly.

 

[Troy Truglio]

Bill,
Good idea. Is there only one radiator on one side? Did you think about running two radiators and one for each side of the engine? I would think you could make them about 3/4 the size and more airflow since both sides. Might even be able to do 1/2 size or smaller and still have more airflow so more overall cooling. Would have to add an extra transfer pipe, but might work out good. Could also keep the cabin cooler and I wonder if it will help with aero at all since there can be less backpressure in the front.

So you will have a front truck (frunk) and for a street car that can be a great idea and would be really nice. Now how are you going to acces this area? And do you have the lift kit because I was wondering where you plan to put that and how you are going to locate that?

I am sometimes glad I have not finished my Mini yet so I can see all these great ideas.

 

[Bill]

I did consider splitting the radiator and putting one on each side. A long time ago I saw where someone else had done that in a white SLC (Rob Mesa?). It sounded like he was having some problems getting enough ram air flow, so he reshaped the rear clam and made the side vents considerably larger. Also, there is twice the plumbing. I'd love to hear how the white SLC is coming, if the cooling system is working OK now, and correct me if I don't have my facts right.

I just wanted to keep it as simple as possible. Locating the radiator on the right side seemed like a natural since the water lines come out of the front of the motor at the center and right side, and the cabin heater is on the right side too.

By placing a single radiator close to the motor, I figure I'll save 30-40 lbs when compared to the long run up and back from a front mounted radiator. The weight isn't so much the pipe/connector/clamp hardware, as it is the water inside those long runs.

The down side is that it moves the stock 60/40 weight distribution toward the back a bit. I normally cruise with a full tool kit, so I plan to secure it as far forward as possible in my new trunk to compensate.
The overall strategy is to keep wire and hose runs as short as possible, so:

• All the cooling, heater and AC components are on the right side
• All the electrical and fuel components are hidden away on the left side

 

[Alex]

Interesting idea but I hope you know what you're doing - the stock setup, when setup properly, bleeds perfectly and holds temperatures solid.

 

[Mesa]

Bill,
The car is gray and yes I did reshape the sides of the car to feed the two radiators, basically took the two existing vents and super sized them to feed much more air. The set up is traditional thinking for radiators in this location and they will be fed with hopefully a good amount of front side pressure and count on back side vacuum to evac the used air from under the clam. Each rad has it's own fan and yes the plumbing is more or less more complicated than with one rad, but it isn't in the front of the car so that helped. I don't have the final word on overall efficiency as the car is not on the road yet.

 

[Jack]

Rob has done a fantastic job on his SL-C. Outside of the box mod's are spectacular!

 

[Ken Roberts]

With no air being naturally forced through the radiator at speed your fans will be running most of the time. Two large Spal fans will be drawing close to 40 amps. You'll need to insulate the rear bulkhead well or the fan noise will drive you crazy.

Proper fan shrouds will need to be constructed as well. Attaching the fans directly to the rad is very inefficient. Also note that you will be pushing/pulling hot air directly towards the fuel tank.

Without proper shrouding you will be sending already hot engine compartment air through the rad only to be distributed in the engine compartment and then remixed again with a bit of cooler air from the side inlet air then through the rad again over and over. You really need a fresh air intake only to the rad.

Over come these obstacles and you've got a fantastic solution.

 

[Fran Hall RCR]

My concern is that rock crawlers may make lots of power but they use it in very short bursts....allowing lots of cool down capability.

Think of a Formula1 or race car not using any fans...they have adequate cooling/heat rejection when moving quickly but as soon as they stop the heat soak and cooling/rejection capability drops off dramatically ..almost immediately overheating..

We can sit and idle all day long with occasional burst , such as a dyno run with no ill effects but when they sit in the pits after having run hard on track, we often burp a little ...and we run fans too....its pretty normal.
The fans work at low speeds , 20-25mph but after that the airflow takes over and makes the fans redundant...

I feel that Bill will need to duct all the air possible into the rad. not allowing any to bleed off or bypass the front of the rad and then also duct the exhaust air away from the rear of the rad efficiently too..

 

[Grant S]

Good luck with this Bill, I have to agree with Fran and Ken on this. Put a winter front on your truck or car this summer and see what happen's.

 

[Dave]

That looks like a bad idea...rock crawler expert guidance or not.

Besides what Fran mentioned, note that rock crawlers radiators are usually completely exposed at the rear so as not to inhibit airflow, coming or going. Your radiator location is the opposite of that.

You may want to consider paneling the triangulated floor area behind the radiator and perhaps the front half under the engine. Air will likely want to come up through those areas and counter any airflow through the radiator making it harder for the air the fans are trying to redirect, which is at least 90 degrees and into the opposite direction of everything else in flow.

I'd consider doing the Mini Mesa Mod to the side intake duct like Howard and I have done.

I hope you prove us all wrong and you always have room for another radiator on the other side.

 

[Bill]

Thanks for your comments.

I agree that I'm playing edge on this design and all things need to be optimized for it to work properly. For example:

• To increase the ram air pressure in front of the radiator, I plan to increase the side vent size a bit and add a scoop at the bottom to pickup air from under the car.
• To decrease pressure behind the radiator, I plan to add a small belly pan to the lower triangular chassis section.
• To decrease the engine bay temperature, the top scoop will channel air in to the rear clam, the LS7 headers and Flowmaster DBX mufflers are insulated, the exhaust tubing is under 24" long and will be ceramic coated and/or wrapped.
• To minimize cooling demands, I'm running a bone stock LS3 (430HP) .
• I will add fan shrouds as needed.

Fran, I'm not sure whether opening the vents at the front of the rear wheel wells will pump air out or allow ram air to bleed into the wheel well. Your thoughts?

This alternative cooling system is all bolt-in, so it's just 6 rivets and 2 screws to undo it if it doesn't work.