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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 01:12
 
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Thats great Nark, but assuming the car is moving, you're constantly going to be running the 30 degree air over the ATA intercooler and not just constantly heating the same fluid up.
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Location:
At work :(
Registered:
June 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 01:17
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not fair... youre fighting with Physics 
I disagree with the starting point of the water. Youre also assuming the air temp is 30deg which is probably a bit high considering you may be doing 80-100kmph and the air is flowing through the cooler to cool the inlet air, whereas the water is static. You are also ignoring the larger size of the air-to-air cooler.
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Location:
At work :(
Registered:
June 2002
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Location:
c'town, NSW
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 01:34
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| itsnotagsr wrote on Wed, 26 March 2003 12:17 |
Youre also assuming the air temp is 30deg which is probably a bit high considering you may be doing 80-100kmph and the air is flowing through the cooler
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?
outside air stays the same temp no mater how fast your driving
this means a/a cannot cool lower than ambient temps (unless helped by sprays etc)
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Location:
At work :(
Registered:
June 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 01:33
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How can an air-to-air intercooler be more efficient than a water based intercooler?
There is an overwhelming quantity of ambient air available to cool an air-to-air core relative to the charge air thru the inside of the intercooler (The iced down water intercooler is the only exception to this argument.). At just 60 mph, with a 300 bhp engine at full tilt, the ambient air available to cool the intercooler is about ten times the amount of charge air needed to make the 300 hp. Whereas the water intercooler largely stores the heat in the water until off throttle allows a reverse exchange. Some heat is expelled from a front water cooler, but the temperature difference between the water and ambient air is not large enough to drive out much heat. Another way to view the situation is that ultimately the heat removed from the air charge must go into the atmosphere regardless of whether it's from an air intercooler or a water based intercooler. The problem with the water intercooler is that the heat has more barriers to cross to reach the atmosphere than the air intercooler. Like it or not, each barrier represents a resistance to the transfer of heat. The net result; more barriers, less heat transfer
from the site above.
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Location:
Cabramatta, NSW
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 01:34
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Yes, I know all this. It was simplified to show the difference in heat that air and water can absorb... It's quiet a difference due to water having a specific heat 4 times that of air.
Air will constantly flow, yes. But the water is constantly cooled also.
The temp differences don't really affect the numbers that much.
If you want 25 degrees then:
Air will absorb 53 joules before hitting 80 degrees.
The size of the intercooler matters in that it gives surface area, but the a/a will have to be four times larger than the w/a before things are equalised. I think.
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Location:
At work :(
Registered:
June 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 01:39
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Yes, but the air is cooler when moving through the fmic whereas the w-t-a is static heat.
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Location:
c'town, NSW
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 01:41
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that example above does not sound like an example of a road car engine where max boost is only held for a short period of time.
it is however a good example for a race car engine in a race car environment
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Location:
At work :(
Registered:
June 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 01:44
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Yes but what are we comparing?
Is this a street drag or say a run round a twisty bit of road? eg Nasho?
The longer your car is being driven hard, the hotter the w-t-a cooler will get and the less efficient it will be given that it will struggle to cool the water and transfer the heat. I think this is where the FMIC will see an advantage.
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 01:45
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I think the point notagsr is trying to make is that, yes, water is more efficient at absorbing heat, and it would take less energy to heat up air to 80 degrees than water, but the fact is, once you're moving, you're never heating up the same bit of air, so there is constantly a supply of cooler ambient air to absorb heat.
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Location:
At work :(
Registered:
June 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 02:06
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Frank,
yep.. glad to see someone understands
Chris
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Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 03:28
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It's great that it's the point your making.
Now stop and realise maybe your not listening to the point someone else is make cause your so busy thinking no-one is listenoing to you.
What you have to compare is if your unlimited less efficient air vs efficiency of water plus small core size and reduced lag.
What if the WTA wasn't over the engine, but to the side like a standard mr2's ATA is?
The current fastest MR2 in Aust has a WTA.
And the st205 engine is the same as the late MR2.
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Location:
Cabramatta, NSW
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 03:46
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| justcallmefrank wrote on Wed, 26 March 2003 12:45 |
I think the point notagsr is trying to make is that, yes, water is more efficient at absorbing heat, and it would take less energy to heat up air to 80 degrees than water, but the fact is, once you're moving, you're never heating up the same bit of air, so there is constantly a supply of cooler ambient air to absorb heat.
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And what's to stop you from putting in a huge front mounted heat exchanger?
That'll cool down the water as fast as it'll cool down air going through an a/a core.
You guys seem to forget that a w/a system has a heat exchanger. It's not a static body of water that just absorbs water.
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 03:48
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I'm not forgetting that at all dude. Point I was trying to make that sure the water is being cooled down, but it'll never get back down to ambient.
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 03:54
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Here's a mathematical formula for you to consider:
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3SGTE > SR20DET > watercooled Vw engine.
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Location:
Cabramatta, NSW
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 04:02
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| justcallmefrank wrote on Wed, 26 March 2003 14:48 |
I'm not forgetting that at all dude. Point I was trying to make that sure the water is being cooled down, but it'll never get back down to ambient.
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And the point I'm making is that it doesn't need to be at ambient. Because of the specific heat, it'll suck down MUCH more heat than air. The air coming out the other side of the i/c will be lower in temp in a w/a unless the water was at insane temps (check the numbers on my example where I've already given the a/a a 15 degree head start). If you've waited for water to boil, you'll realise how long this will take.
Yes, prolonged time on boost will eventually get the water past this point, but you'll only really get that in motorsport.
Plus, there's also the advantage of near-zero water temps for short bursts if you're willing to play that game.
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Location:
Sydney
Registered:
March 2003
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 04:31
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Location:
was adelaide now newcastle
Registered:
February 2003
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 06:20
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at risk of being involved in a forum war.. heres my 2cents (more like $1.28)
1) from what i know yes WTA is better at heat transfer(more efficient)
2) WTA lowers lag (both turbo and s/c due to shorter intake tract)
3)WTA also weighs a shit load (1Kg for every litre of water, usually need several litres of water, heat exchangers, water plumbing, and an electric pump
4)due to ammount of parts involved WTA has more sites for reliability issues to arrise (electrics for pump, water leaks,)
5)WTA is usually more expensive to implement.
6)A/A has awsome wank factor
7) A/A also can suffer from heat soak, ie after lots of boosting, although when cold will work (perhaps better than WTA)but the stability of the WTA can be seen as a bonus to those not drag racing.
8)although the heating of water in the WTA is obvious the heated water will still have great heat exchange efficiency (this can be shown by the fact that subaru only ran the pump intermittently in the original RS liberty indicating that warm water will still pull more heat out than air which is slightly cooler -(specific heat value differences)
just out of interest i do have a front mount A/Aintercooler in my gze powered AE86, (evo3 lancer) but due to excessive lag (massive volume for intercooler and pipework)the idea of encasing a factory gze intercooler in alloy and riging up all the other associated stuff (and perhaps a seperate radiator for dry ice) appeals to me -one day i'll do it.
of interest how many people believe that crap about painting intercoolers black for "better heat transfer"????
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Location:
Cabramatta, NSW
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Wed, 26 March 2003 06:30
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Yup, w/a is much more unreliable since there are many, many more things to go wrong.
The w/a pump can be turned on only on boost due to the fact that the water being pumped in is from the heat exchanger, therefore at ambient temp.
As for the black paint, I've been told that it's gotta be a certain type of paint and also it can't be too thick (otherwise it'll act as a barrier rather than helping).
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Location:
Wellington, NZ
Registered:
March 2004
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Re: MR2 Vs S14 200SX Vs WRX
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Sun, 11 April 2004 09:08
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Getting back to some of the other points the ST205 3sgte is the same as the Gen III sw20 3sgte with the exclusion of the wrc edition which only had the ic spayers + disconnected antilag etc otherwise there the same. The difference itsnotagsr talks about is probably between the Gen II & III 3sgte. He also mentioned the "lack of traction vs awd " only in the wet...on a dry day the MR2 can lauch just as good if not better than a 4wd as it has all the weight over the rear wheels....Iv'e out launched many a evo & wrx etc etc just takes more practice to get it down to an art than a 4wd.
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"limited mods available to turbo"
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Hmmmm....news to me, why do you say that??
GSR's are OK...there still only 1.8 ltr and don't like much boost, more comparable to a Gen II MR2..no comparrision to a Gen III.
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The 3sgte is limited to about 1.3 bar before it starts lifting the heads and you need to start thinking of strengthening it.
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1.3 bar...maybe the ct26 but the ct20b will happily provid that sort of boost on a MR2 with just exhaust and intake...an aftermarket would be nice but not crucial. The 3sgte is dead safe to 400 hp with stock internals...500 if ya wanna push it to it's limits.
Cheers
KiwiMR2
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Location:
Colac, Victoria
Registered:
May 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Sun, 11 April 2004 09:32
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mr2 turbo if you want " mini ferarri with the go to match the looks "
s15 if you want parts availability and many many avenues of aftermarket modification cheap and 2 useless rear seats too small to fit a baby carriage
W to A - like on a gt4 has the advantage of short intake path ! With an under heat shield , constant pump running and decent coolant fluid ( toyota red ) ive heard of quite well cooled charge levels ..
Couple this to water injection and well - youve got one very very eficient street setup woithout all that extra piping to play with ..
the toyota ones are rated as one of the best charge coolers about - and theres better versions from TTE as used in the rally cars.
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Location:
Brisbane
Registered:
July 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Sun, 11 April 2004 10:15
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so much bitching about intercoolers lol
Id go an mr2, besides handling better than both it has the best engine out of all 3 stock for stock, less aftermarket but its still there
they are well less common
make sure its a turbo one though.
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Location:
Potts Point, Sydney
Registered:
October 2003
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Re: MR2 Vs S14 200SX Vs WRX
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Sun, 11 April 2004 10:47
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personally i'd get a 200SX...for some reason i love them...if you can whack in a rb20DET or rb30DET it'll fly like a biatch...
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Location:
Brisbane
Registered:
July 2002
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Re: MR2 Vs S14 200SX Vs WRX
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Sun, 11 April 2004 11:04
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or if ur feeling rich an rb26
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Location:
northan beaches
Registered:
March 2004
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Re: MR2 Vs S14 200SX Vs WRX
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Mon, 12 April 2004 13:48
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i used to own a 4wd turbo car. at first you love the grip and wow your mates with corner exit speed and 0-100 times. then you get board with the grip and try to exceed it. you soon find out that the limits are VERY high and when you get there you will either be in alot of trouble or need a new gear box, trust me a lot of $$$$. i did this. soon you will find your self borrowing your dads auto falcon just cause it is fun on a twisty road.
get a mr2 (i had an aw11) you will love the response and it it's alot more fun and just as fast if you get it right. or if you want to be safe and boring get a wrx. don't even start me on the sr20. i know there is alot of aftermarket for these. but do any of the big time Japanese races use them??? however the top cars for the last few years take out a supra 2jzgte and drop in a 3sgte..... they are very rarely wrong about this kind of thing. and have only now been replaced by the 4L N/A v8.
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Location:
sydney
Registered:
September 2004
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Re: MR2 Vs S14 200SX Vs WRX
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Sat, 09 October 2004 09:52
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simply...
which is faster in the straight line?
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