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Old 06-20-2012, 07:19 PM   #1476
bue car
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looking good.
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Old 06-20-2012, 07:40 PM   #1477
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i'm curious about balance after removing the spare. I would like to do this (seeing as its a really quick way to drop a few pounds), but how does this effect the front/rear balance of the car?
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Old 06-20-2012, 07:46 PM   #1478
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Quote:
Originally Posted by Nekronaut
i'm curious about balance after removing the spare. I would like to do this (seeing as its a really quick way to drop a few pounds), but how does this effect the front/rear balance of the car?
I haven't had the spare in my car in months.
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Old 06-23-2012, 06:31 PM   #1479
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It's about 25-30 lbs off with all spare kit removed. Not totally significant overall, but definitely a difference in feel. As the rear end is already lighter than the front, definitely try attacking the front. I'd definitely do a battery relocation.
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Old 06-23-2012, 08:00 PM   #1480
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Dss carbon shaft and the tomei ti exhaust coming soon
That should save me a few lbs
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Old 06-29-2012, 09:37 AM   #1481
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68Caddy, Still running the turbo coolant reservoir(bolts to the intake)? Does your radiator have a cap?

Take that off, hook the two hoses together, and weigh!

It might be a little more work to bleed the coolant system, but that doesn't look like something that will scare you
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Old 07-02-2012, 07:49 PM   #1482
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Quote:
Originally Posted by tachrev View Post
68Caddy, Still running the turbo coolant reservoir(bolts to the intake)? Does your radiator have a cap?

Take that off, hook the two hoses together, and weigh!

It might be a little more work to bleed the coolant system, but that doesn't look like something that will scare you
Not sure that would be good idea as it cools to turbo off after turning the engine off. If you still have the metal one you could replace with the plastic version from Subaru. It weighs less and is more reliable.
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Old 07-03-2012, 09:11 PM   #1483
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Quote:
Originally Posted by tachrev View Post
68Caddy, Still running the turbo coolant reservoir(bolts to the intake)? Does your radiator have a cap?

Take that off, hook the two hoses together, and weigh!
In a previous post in this thread I posted it's weight. I've always assumed that the up coolant reservoir was vital to getting and keeping air out of the cooling system. Air will get back in there no matter how well you bleed the system, according to Carroll Smith's books. So you need to have a system that continually removes the air that does get in. And the Upper Res is vital to that. I suppose I could weigh one of the plastic ones and see if there's any savings to be had there.

Quote:
Originally Posted by 68Cadillac View Post
Lost a bit more.

It's 2 pounds even (empty) and without the cap.


****. All that effort and only lost 3/16 lbs.
Looks like the OEM weighs: 907 grams

My modified one weighs: 822 grams
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Old 07-03-2012, 09:15 PM   #1484
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Quote:
Originally Posted by 68Cadillac

In a previous post in this thread I posted it's weight. I've always assumed that the up coolant reservoir was vital to getting and keeping air out of the cooling system. Air will get back in there no matter how well you bleed the system, according to Carroll Smith's books. So you need to have a system that continually removes the air that does get in. And the Upper Res is vital to that. I suppose I could weigh one of the plastic ones and see if there's any savings to be had there.
It's more critical for pulling coolant up through the turbo.
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Old 07-03-2012, 09:20 PM   #1485
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Quote:
Originally Posted by sc00by4life View Post
It's more critical for pulling coolant up through the turbo.
Huh? The coolant system works on pressure not vacuum.
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Old 07-03-2012, 09:29 PM   #1486
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Quote:
Originally Posted by 68Cadillac View Post
Huh? The coolant system works on pressure not vacuum.

With the motor off, there is a siphon effect in play that keeps the coolant moving after you turn the car off.
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Old 07-03-2012, 09:36 PM   #1487
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Just installed some AMS lightweight goodies - tubular front bumper beam and the race battery kit. Huge improvement in every aspect of performace
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Old 07-03-2012, 09:41 PM   #1488
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Quote:
Originally Posted by 68Cadillac

Huh? The coolant system works on pressure not vacuum.
I'm talking about the turbo. After the car shuts off the cooling system goes into vacuum. That's how coolant keeps cycling through the turbos after the motor is shut off....
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Old 07-03-2012, 10:07 PM   #1489
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Quote:
Originally Posted by bue car View Post
With the motor off, there is a siphon effect in play that keeps the coolant moving after you turn the car off.
No kidding? Learned something new. Thanks.
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Old 07-05-2012, 09:50 AM   #1490
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Here's how I see it:

Turbo Cooling after Shutdown: The siphon effect should still happen, even without the tank. There is still plenty of coolant in the system for this.

The tank does not cause or stop the siphon action. The fact that the coolant in the turbo is hotter than the coolant in the rest of the system does this. It's called conduction, I believe.

Also, there are LOTS of liquid cooled turbo setups, factory and otherwise, out there that do not have a tank near the turbo.

Air Pockets: After getting all the air out of the system, you should be fine.

If you have a working radiator cap and your coolant overflow is not empty, you should get no new air pockets in the system.

When you shut the car off and the coolant cools, it contracts. Coolant from the overflow will be drawn in to fill the void.

When it heats back up and expands, it will be pushed back into the coolant overflow. That is how a sealed system works.

I've checked mine after it cools off and the coolant is always right at the top of the radiator.



I felt the the coolant tank was mostly there to be a high point in the system to make filling/bleeding easier.

Now I am no engineer, just a car guy. I removed mine and I don't worry about it.

If your not comfortable doing so, no worries. Just wanted to point out my reasoning.

I saw you did a lot of other things people might consider crazy to remove weight. Just another one to think about.
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Old 07-05-2012, 10:54 AM   #1491
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The cooling our turbos get after engine shut down is called thermosiphon. It's a convection heat transfer mechanism. The hot fluid expands and the density drops. This is why hot air (fluid) rises. Cooler fluid is moves down to replace the rising hot fluid by gravity.

It was used in the model T. No water pump. Nothing new under the sun. Speaking of sun, you can see air convection on a hot day with the "heat" rising off of a road. The current's are so strong that there is optical distortion looking through them.

Yes, I'm a dumb mechanical engineer.
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Old 07-05-2012, 11:14 AM   #1492
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Quote:
Originally Posted by Web Foot STi View Post
The cooling our turbos get after engine shut down is called thermosiphon. It's a convection heat transfer mechanism. The hot fluid expands and the density drops. This is why hot air (fluid) rises. Cooler fluid is moves down to replace the rising hot fluid by gravity.

It was used in the model T. No water pump. Nothing new under the sun. Speaking of sun, you can see air convection on a hot day with the "heat" rising off of a road. The current's are so strong that there is optical distortion looking through them.

Yes, I'm a dumb mechanical engineer.
I knew there was a technical term for it (as there is for everything).
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Old 07-05-2012, 12:48 PM   #1493
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The tank may be a precaution used for the longevity of the oem turbo, to avoid turbo failures for the everyday person.
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Old 07-05-2012, 03:06 PM   #1494
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I thought about it a little more. Since thermosiphon is driven by the fluid's density gradient and gravity there needs to be a height difference between the top of the turbo and the top of the radiator top tank. Most cars have the turbo(s) mounted low in the engine compartment. Subaru has the turbo mounted relatively high, and the radiator relatively low for better aerodynamics. There isn't much head to drive the flow without the aux header tank. I'm sure Subaru would love to leave cost of that tank out if it was not needed.

If the top tank/aux tank was below the turbo there would be nothing driving the fluid loop and simply cook off at the turbo outlet.
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Old 08-13-2012, 05:44 PM   #1495
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Thought I'd join the fun of this thread, My car used to be lighter than most of the target goals...

I'v read the first 8 or so pages and the last 2.. i need to go back and read all the middle ...

My car is a 1993 Subaru Impreza. For 3 years i rallied it as a production car 1.8L FWD. the last time i had it on car scales, wet (with a full tank of gas) she weighed :
2450 It was in log booked Trim, but not passing tech trim. car was wet, with a full tank of gas, a full sized spare tire, and the stock scissor jack.

Since the weigh in i've added 2 fire extinguishers, first aid kit, spill kit, and rattle gun.

a year later I added a few more roll cage bars (new 09 rules) . and since then i've done a full RS 2.5 swap . the 93 owners manual says the awd version is 175 lbs more which would be 2625 + all the other stuff i listed.

So i think my car is around 2700 lbs and I've been raciing it in a production trim (plastic piller trim, stock doors, windows, battery, etc)

I'm going to begin a weight savings operation for my car. I do comute in my car on a very frequent basis, but i'm not overly converned with keeping it "comfy" its not comfy at all ... I want to modify my trunk & hood by cutting out all the extra metal that gives it stregnth (no more standing on the hood or trunk) and possibly even the C pillers (I've got a roll cage and no back seats ... why not? )
gut the doors
replace glass with lexan (except the windshield)
light weight battery
???? Ideas ? I'd like to replace the bumper beams (or remove them) but being that its a rally car , crashes are common and usually (hopefully) you smash your front end (first) ... though maybe i can use a roll cage pipe that would be stronger and lighter?

ideas?
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Old 08-13-2012, 06:01 PM   #1496
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Custom front bumper. Exactly like you said, stronger and lighter.
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Old 08-13-2012, 06:11 PM   #1497
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hi buddy
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Old 08-15-2012, 03:19 AM   #1498
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I did both front and rear with 1.75inch diameter DOM steel, same as my rollbar. saves ~20 pounds over the stock bumper beams and costs all of $20 to make if you have a welder and bender handy.

front beam after ~35mph impact into a boulder



Decided to do a tube front end after the accident, this front end ripped a diamond plate bumper off a taco truck and simply bounced off with almost no damage to my car. I replaced one headlight and straightened the fender a bit (free headlight, 1 hour labor), the taco truck needed a new diamond plate bumper because i mashed it up and ripped it off the welds that held it to the frame ($1200).



Rear beam:


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Old 08-15-2012, 04:38 AM   #1499
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Nice job with the tube front, looks great!
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Old 08-15-2012, 06:49 PM   #1500
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Got a very small start last night. tore out 15 pounds of "stuff"

i still had some A,B & C piller trim in the car (was running in a production class)

and i tore off the rear door cards . i was kinda surprised it added up to 15 lbs. Eager to tear into the rear doors but i need to wait for some professional / (knows wtf he's doing) type help

I really like the idea of using a roll cage tube for the front bumper beam, and the same with the rear...

hmm
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