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> Idea: Twin Intercooled
post Oct 8, 2003 - 6:08 PM
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Inferno



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Several people have inquired in the past about Twin Turbo. More recently it was discussed that a Twin Turbo setup on a four-cylinder is completely pointless. We all know that turbo's create unwanted heat. I had the idea, while sitting in class today, of a Twin Intercooled engine. I don't know if anyone has ever done it, but I'd like to ask about it.

We all know that the 3S-GTE has a Top Mount Intercooler. I've read threads about putting a FMIC (Front Mount Intercooler) on a 3S-GTE engine. People have said it is possible, but it would need custom piping. So, this brought about the idea of a Twin Intercooled engine.

I figured if a person could mount a FMIC on a 3S-GTE (with custom piping of course), then why couldn't they simply connect it to the TMIC and have double the cooled air charge. I figure it would keep a high-powered engine MUCH cooler than normal. I also figured it was possible since there isn't a FMIC stock with the 3S-GTE engine, therefore there is the space to do it with.

Get back to me, people! I appreciate all who contribute!

This post has been edited by Inferno: Oct 8, 2003 - 6:08 PM
post Oct 8, 2003 - 6:31 PM
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sphinx



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YES. you can do it. but once again, it's pointless.

why have two intercoolers?

1 FMIC that provides cold air and a TMIC that porduces WARM air.

One of the reasons ppl upgrade to a FMIC is because the TMIC is on top of the engine.

A engine that gets real HOT. It cools down the air fromt he turbo, but it's still somewhat hot because of the fact that its surrounded by so much HEAT.

I say just get a good FMIC and hook up a sprayer to it.

That's just what i think.

This post has been edited by sphinx_race911: Oct 8, 2003 - 6:32 PM
post Oct 8, 2003 - 6:39 PM
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Inferno



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I know why people ugrade to a FMIC. But I was just thinking that the TMIC wouldn't hurt and would actually help. But I could be wrong. Thanks for the input!
post Oct 8, 2003 - 6:53 PM
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jayi12-15psi

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yea, but just the idea of the fact that the fmic will always be cooler than the tmic, so yes, the tmic would actually hurt performance. good job bein creative thou


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post Oct 8, 2003 - 7:27 PM
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Inferno



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Are you sure? Cos if you think about it...the TMIC does support the 3S-GTE beast. Maybe I'm just throwing out dumb thoughts. But I do appreciate your thoughts. smile.gif
post Oct 8, 2003 - 8:16 PM
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Xpander

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If you were to run both a TMIC and a FMIC you probably wouldn't benefit much. The added capacity of both intercoolers would most likely be so much that it would lower the pressure, therefore making less boost by the time it gets to your engine.

Colin
post Oct 8, 2003 - 10:31 PM
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FallenHero



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Agreed. Two intercoolers, while making the intake charge temp lower, would put a load of strain on the turbo to push air through two IC's.

Jon
post Oct 8, 2003 - 10:37 PM
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97sccelica



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1. boost pressure would drop by about 1psi

2. boost would come on later

3. puts mroe restriction on the system.

1+2+3= not good.

3000gt vr4's are twin intercooled as with 300zx TT's but that is because they have two turbos on v6 engines. the turbos are on opposite sides of the engine so they make the system symmetric to have the same restriction on both turbos to balance the system.


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post Oct 8, 2003 - 11:18 PM
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1bwilson



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QUOTE (97sccelica @ Oct 8, 2003 - 8:37 PM)
1. boost pressure would drop by about 1psi

2. boost would come on later

3. puts mroe restriction on the system.

1+2+3= not good.

3000gt vr4's are twin intercooled as with 300zx TT's but that is because they have two turbos on v6 engines. the turbos are on opposite sides of the engine so they make the system symmetric to have the same restriction on both turbos to balance the system.

Agreed. You will have hella boost lag with 2 intercoolers.

-Bryan-


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post Oct 8, 2003 - 11:44 PM
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jayi12-15psi

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it would be sick and I would throw up


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post Oct 9, 2003 - 12:34 PM
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Chrobis



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I agree with pretty much everything said... the best option would be to just get a bigger FMIC for more cooling.

PS on a 205 the IC would most likly work in helping cool but boost loss and resistance would still be bad.
post Oct 9, 2003 - 12:57 PM
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You gotta realize that the GT4 was a rally champion and whoever thinks the TMIC is pointless and useless and a bad idea, doesnt kno. The way the GT4's were produced provided plenty of cold air, and yes the FMIC is away from the engine and thus cooler, but it also provides more turbo lag. You gotta pump air throught the front of the car, with the TMIC its connected to the turbo and throttle body. Your getting air quicker and its having less time to heat up. By the time the air from the FMIC gets to the throttle body, its probably pretty close to the same temperature.

Also, the engines dont cool from air, thats there so you have a lil thing called combustion. The COOLANT cools the engine and thats why your big radiator is in the front of the car. Same concept on the ST205 IC which is both water and air cooled.

This post has been edited by Supersprynt: Oct 9, 2003 - 1:00 PM


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post Oct 9, 2003 - 2:42 PM
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SpedToe169



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For starters the difference in pumping losses between a TMIC and a FMIC aren't going to be much. You'd have a lot more loss from the pressure drop across the intercooler than you would from the piping. So thats not really a valid argument. Second, underhood temperatures do matter. The engine might be 'water cooled' and although a large percentage of its cooling comes from that, the cooling due to air circulation is not negligible on high-powered cars. Why do you think lots of touring cars have hood vents? If its good enough for factory BMW teams, then its good enough for me.

QUOTE
but it also provides more turbo lag. You gotta pump air throught the front of the car, with the TMIC its connected to the turbo and throttle body. Your getting air quicker and its having less time to heat up.


The heat in the intake charge is due largely to the compression of the air. It doesn't really matter how 'long' it takes to pass through. As far as getting air 'quicker' thats totally a misnomer. You have to think of the intake charge as continuous. Turbo lag isn't at all a result of 'how quickly' you get air into the engine, its a result of the time it takes for the rotational speed of the turbo to increase enough to make boost.

Back to the original question in the post. Its not worthwhile to have to air to air intercoolers for all the reasons that everybody else stated, they're all pretty much correct. It might be feasible and beneficial to have an air to air and a water to air intercooler. The added complexity may not be worth it on the street but when drag racing you could fill the water resivor with ice water and keep everything that much cooler. This wouldn't really make sense on anything that wasn't really built up.

One thing you have to keep in mind with all this intercooler talk is the efficiency of the core used. This will effect both the pressure drop across the intercooler and the change in temperature of the intake charge across the intercooler. The efficiency can be affected by many things, but you should always keep it in mind when choosing an intercooler. Spearco is one of the few companies that I know of that actually takes the time to know what their efficiencies are and as a result, they make about the best intercooler cores you can buy. Theres a good reason why they're so expensive. smile.gif
post Oct 9, 2003 - 8:08 PM
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What im saying with the time it takes for the air to get to the throttle body is that it has more time to warm up and that just happens u cant help it. And i disaggree with the pumping air throughout the car because if you have a FMIC its like 3x the length the air has to travel and thats definately a factor.


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post Oct 9, 2003 - 10:15 PM
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95ST

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If you are concerned about cooling your temp more what about a n'tercooler, instead of a second intercooler,

only have 1 intercooler and have colder air. And its probably cheeper to install than 2 intercoolers
post Oct 10, 2003 - 9:16 PM
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SpedToe169



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QUOTE (Supersprynt @ Oct 9, 2003 - 7:08 PM)
What im saying with the time it takes for the air to get to the throttle body is that it has more time to warm up and that just happens u cant help it. And i disaggree with the pumping air throughout the car because if you have a FMIC its like 3x the length the air has to travel and thats definately a factor.

QUOTE
What im saying with the time it takes for the air to get to the throttle body is that it has more time to warm up and that just happens u cant help it.


Ok, I'll go with you on that one. I think the actual length of the piping is negligible but the effect is there on some level.

QUOTE
And i disaggree with the pumping air throughout the car because if you have a FMIC its like 3x the length the air has to travel and thats definately a factor.


You're right, it definitely is a factor, but its not enough of a factor to matter. The restriction due to the intercooler and, in engineering terms the 'K factor' associated with the intercooler(s), is much higher than the K factors associated with straight piping sections and with mandrel bends (crush bends are a whole other story, stay away from them!).

Just to put some numbers with this, its pretty common to see a 1 or 1.5 psi pressure drop across an intercooler (due to the restriction). Ten feet of tubing and say...six mandrel bands will produce a pressure drop of about 0.1 or 0.2 psi at the flow rates and velocities that we're talking about. The size limitations on a TMIC mean that it usually can't be as big and can't flow as well as a FMIC so this fact more than negates the losses due to the extra tubing required for an FMIC.

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