Malc50

Hi All

Before I get shot down, apart from cooler charge temps What other effects would you expect to see from fitting a larger intercooler..i.e more lag ,less lag, hold more boost????

Cheers

Malc

PGT

some peeps beleive that a larger volume intercooler will give more lag but cant see the logic in this myself - size matters!

Anonymous

the bigger volume will give more lag if you use a dump valve too, as the turbo has to first refill that intlet pathway before it gets anywhere near the plenum.

never noticed it happening on a non dump valve car though, which makes sense as the cooler stays pressurised.

wayneclayden

lighter wallet

a propperly designed and researched cooler will have no adverse effects, just a gain in power, torque and throttle response.

Malc50

Thks Guys....

wimwerf

but without a dv..the air go back trough the turbo which slows the compressor wheel also....

Anonymous

A remap.

Anything changed on the engine needs to be checked and possibly remapped.

Mike Rainbird

iTrader: (3)

Chip,
Crock of shit . I don't think you realise just what volume of air a turbo produces (around 800cfm for a T4), do you really think increasing an intercooler by a few cc is going to be noticed . A bit like spitting in a pond and being able to expect to visually detect the increase in water level .

I've just fitted a mahoosive intercooler and noticed nothing but what Wayne has stated. The only downside was that it is so efficient, it needed shit loads of fuel putting in at the top end . Where it used to det at a held 1.9 bar (due to the high compression - hence why I had it set at a held 1.7-1.8) with the RS500 intercooler, it is now det free (with the extra fuel) .

PGT

says it all really

Anonymous

So mike did you run out of fuel on the greens - just to see the power you now have

Mike Rainbird

iTrader: (3)

That information is classified .

Anonymous

But your still on the greens at standard fuel pressure

Anonymous

Mike, many of the larger coolers people use are 10 litres+

Thats enough for 20 engine cycles!
Thats a thrid of a second at 4000rpm mate!

A third of a second is NOT a spit in a pond, not by a long way!

Anonymous

PS

A T4 cannot flow 800cfm when there isnt any boost going into a low compression 2 litre engine (and hence not as much exahust gas coming out) either mate, so you are wrong to think that the instant you are back on the throttle the turbo is instantly at its most efficient again, its not, its a fraction of a second later.

Also thats a far larger turbo than most people use on a cossie lump anyway, and highlights the fact that for larger turbos the cooler volume is less of an issue (which i agree with), but with a little T3 desperately trying to maintain 25psi into a volume that size at the same time as you remove a load of the exhaust gas pressure behind it, the difference IS there!

So wether you think its a crock of shit or not doesnt actually change the reality!

As usual mike you are just looking at it purely from the point of view of your own car and cant see the bigger picture.

Mike Rainbird

iTrader: (3)

Chip,
My intercooler must be around 15-20 litres, and believe you me, 800cfm (i.e. 22,650 litres per minute), has no problem filling it . NOW do you see how nonsensical it is what you are saying . So do you honestly think that even increasing your intercooler size by 100% from 10 litres to 20 litres would be noticed when the turbo can flow 22,650 litres of air per minute .

Now it's YOUR turn to be wrong - just admit it .

Even a smaller turbo of 500cfm is still 14,160 litres a minute , so what is 20 litres as a percentage of that . Even when it isn't at peak efficiency, it is still thousands of litres per minute .

Anonymous

Mike, things to consider:

20 litres @ 2 bar takes 60 litres to fill.
Assuming you manage to keep the turbo at nearly half its effiecency during the time when there is less air entering (and hence less leaving and hence less pressure on the turbo) then you are only flowing around 10000 litres per minute.

So thats only 166 litres per second, so still nearly a third of a second to fill that cooler completely with 2 bar of boost!!!!

Which bit of that dont you understand?????

Anonymous

Just seen you edit mike, right 14K at maximum efffiency for a smaller turbo qutoed by you, thats 233 litres per second at atmopsheric pressure.

Now lets pretend in mike's magical mystical world that turbo can manage to maintain maximum effiency even during a gear change with a closed throttle and no air going through it (does that really sound likely to you, cause if it does you are more of a blinkered fool than i thought!) that means you need to fill a cooler with 60 litres of air (at atmposhperic), so thats STILL over a quarter of a second, and thats assuming the turbo is still at 100% of its max flow!!!!!!!


Those are very very basic sums, how can a moderately inteligent person like yourself be so foolish as to not see that?

Mike Rainbird

iTrader: (3)

what-ever you say

Anonymous

DO THE MATHS YOURSELF MIKE


Come on, you are throwing these things around left right and centre.

YOU TELL ME HOW LONG YOU THINK IT TAKES A TURBO OF T4 SIZED TO REPRESSURISE AN INTERCOOLER TO TWO BAR?


Ive actually spotted a slight flaw in the maths i just did TBH, as obviously i only whacked those numbers up quickly off the top of my head, and ive got it out by a factor of a third at 2 bar (forgetting that DV only drops pressure to zero at worst case not to a vacuum like i had calculated based on) but you are still talking a whole .2 of a second!
(especially given that ive deliberately ommitted the fact the engine is trying to consume the air at the same time the turbo is trying to fill it, as i cant exactly quantify that in a rush, so ignored it, which skews the numbers massively in your favour and yet they are still damning!)

See if you can make the maths come out with less than lets say a tewentieth of a second (anything under a twentieth i will concede is not a signifcant amount of extra lag, although many drag racers would disagree!),

Mike Rainbird

iTrader: (3)

The fraction of a delay is there what-ever the size of intercooler - which part of that don't you understand ? Because of the air flow capability of the turbo compared to volume of the intercooler, increasing the size of intercooler will NOT increase the delay in filling it by any measurable amount UNLESS the intercooler is 1000 litres .

Anonymous

You call .1 or more seconds difference between 10 litres and 20 litres, even on a largeish turbo a "not measurable amount"????

Mike Rainbird

iTrader: (3)

Chip,
It is already .1 second . Try it on your car... Then try it with a bigger intercooler, it will STILL be .1 second .

Anonymous

Mike, you are honestly telling me that you believe it will take the same time to fill double the volume?

It will be around .1 seconds for a small intercooler on even a largeish turbo, and it will be a quarter of a second or more on a huge intercooler.

You are concedeing that filling a 10 litre intercooler takes .1 seconds, but your brain is too tiny to extrapolate from that the fact that (given you are already assuming max flow of the turbo so that cant possibly improve) it will be double that for a cooler twice the size?
(not exactly double of course between 10 and 20 litre coolers, as its whole inlet volume that counts including the pipes etc, but 10 and 20 were numbers you picked, which are hardly an extreme case i know of people who have increased intercooler size by 300% or more on some cars!)

GARETH T

chip there is a floor in your plan

you are saying that the reason there is lag there is because of the volume of air it has to fill??

what about exhaust energy?

Anonymous

No flaw there mate, think about it, for the example we just did i let mike assume that the turbo was still running flat out, so we have assumed thee is utterly no drop in exhaust energy or turbo speed.

So where is that going to cause a flaw?

Anonymous

PS

Im not just basing this on some maths, i have actually tried it and seen the effects in real life (wasnt on a cossie engine, but principle is the same for any engine of course)

GARETH T

i do agree with you in that it will be a difference,,, just how much of one,, ill have to think about it

Anonymous

Well if you can manage that, it will put you one step up the evolutionary chain from Mike.
The best we can hope from him is that he phones harvey, him actually thinking about it himself isnt even vaguely possible it would seem!

GARETH T

you are saying that the volume of air which the turbo in pumping into is static aswell,,, but it isnt,, its a function of the engines ve and turbo to thrttle plate volume

Anonymous

Yes i know, i mentioned that in one of my replies above, the engine is actually consuming air at the same time the turbo is trying to pressurise the system, so its actually a worse case than it looks like in terms of how long it takes.

Mike Rainbird

iTrader: (3)

Chip you flid, you do the maths and then get back to me . I'll point you in the right direction though - lets say there is currently a 0.1s delay. Let's also say that the turbo ONLY flows 7,000 litres per minute at the point you come back on the throttle and lets say the volume of the intercooler goes from 10 to even 50 litres, (that is a huge increase), that still only represents an increase from 0.14% to 0.71% of the flow capability of the turbo (before it gets properly on song even ). You honestly think you can notice 0.57% inrease on 0.1s .

Anonymous

Mike, what on earth are you on about, seriously?

In order for the inlet system to be back at (for exmaple) 2 bar of boost, its simply a case of the time taken for the flow of the turbo to exceed the consumption of the engine by the volume of the inlet * 2.

So if you go up to 50 litres (80 litres extra at atmosphere), then even assuming the engine consumed no air at all, and the turbo was flowing 7000 litres per minute, thats going to be well over half a second before its back up to 2 bar again.

So yes i am confident i would notice a 50% drop in power for .5 of a second (on a slope from 50% to 0% drop over that period of course, its not an on/off thing), if thats the question you are trying to ask, which i cant honestly say im clear about (what you are asking i mean, im clear about how it all works)

Phone Harvey again and get him to explain it to you a bit better this time

Mike Rainbird

iTrader: (3)

We'll have to agree to disagre then, as I have just changed the volume of my intercooler by several hundred percent and noticed no difference what-so-ever . Test, don't guess .

Anonymous

I have, as mentioned previously in the thread.


BTW - just to clarify, im not saying that im against big intercoolers, i run a rs500 one on mine which is a pretty large IC by any standards, im just saying that if you go too over the top with it (ie RS500 intercooler size on a renault five with a standard turbo or similar extreme example) that you will get a marked difference in time to build boost up.

On a cossie going from a 4wd cooler to an rs500 cooler for example, the difference is small enough not to worry about given the gains that you will see on a hot day on boost, but thats not the context the question was asked in, it was far more theoritical than that and not a specific example of a sensible change (like your own car).

Mr C

iTrader: (2)

so in answer thats a yes to most of the above then. only getting less lag if its designed to flow better than the original if it was similar size though. Lots to think about above.

Anonymous

Simple answer is that a well designed cooler with a moderate increase in volume (ie 100% or less), is going to make noticeable gains on boost, but not cause a significant enough amount of extra lag to worry about.

So as a general rule of thumb, bigger is better providing you dont go silly with it.

Mike Rainbird

iTrader: (3)

You should see the following, depending on the design:
1. Lower ACTs
2. Possible increase in boost
3. Air that is more dense at specific points, thus requiring more fuel (i.e. a possible remap).
4. No noticable increase in lag*



*Depending on size of turbo and intercooler - i.e. T2 with 10 x 2wd cores would be a no-no .

Anonymous

Mike, Re: 2

Ofen (due to the air becoming denser) people see a DROP in boost.

Eagle lost about 2-3 psi when fitting his RS500 cooler he claimed at the club meet.
(although that was a little higher than i would have expected its not contrary to what ive seen previously)

Malc50

Question answered in only a way Passionford can

Thks for all the input, cheers Malc

Alg1k

iTrader: (2)

Another one
You will have less space