Scuba

My mate is wondering if this is possible without 'leaning out'.. he does have a fuel pump/reg.. and green panel

I said to him the FMIC would cool the charge not increase it thus making more power without ars*ing about with the boost.. am I right?

Delboy2

Fitting an FMIC will cause the charge temperature to decrease thus causing the air to become more dense to the extent it may cause the AFR to lean under boost conditions. Ultimately a remap would be advisable

Cheers

stevie boy

any increase in power on a standard car on a dyno would proberly be canceled out in real world driving because of the extra lag. IMHO

stevie

Jolly Green Monster

iTrader: (4)

here we go again.. lag is myth.. and is complete rubbish!

I took a not far off standard MY96 and fitted a FMIC and there was no increase in lag..

Would be best to remap the car to gain the benefits of the fmic and to ensure not running lean, or you could fit knock link, afr and adjust the fueling accordingly.. remap safest though.

JGM

Delboy2

I would deffo agree with JGM When I fitted my FMIC to MY96 I did have additional modifications but didn't notice any increase in turbo lag. If the car was mapped with the FMIC there would likely be power/torque increases due to the significantly lower cooler charge.

Cheers

chucknorris

Jolly Green Monster:

I hope you don't mind me picking you up on something for my first post.

What you say (and a few others have said similar things recently) is not stricktly true about "Turbo Lag", although it is true that it generally doesn't cause any "noticable" increase.

If you think about the fact that a Turbo is a compressor, with a standard TMIC the volume of air to be compressed is far less than the volumes of air involved with FMIC's. So the fact of the matter is that with TMIC's the pressure is built up faster than with FMIC's because there is less air to be compressed, especially if the front mount has pipes running all over the place and has a much bigger intercooler. BUT... the fact is that unless you are doing things like shoot-outs or track racing, i would imagine most people wouldn't notice any difference or have a problem with it.

Maybe the best way to put it would be to say that: lag does exist and will increase with a FMIC but it is not significant enough to cause a problem. As Delboy2 put's it:
So maybe it isn't so much a "Myth", more an "un-noticable fact" ( how about that for coining a new phrase )

Jolly Green Monster

iTrader: (4)

I think you are under estimating the practical hand on fact that many many people have done this and noticed no increase in lag.

Two of us alone in this thread have mentioned we noticed no increase.. I do drag my car occasionally too.. and will be at the shootout at the end of the month and a number of people track their cars with fmic.

Harvey who I am sure will not mind me mentioning also said that he never noticed an increase in lag when switching to a fmic and his last RR was 585bhp and his was the quickest Scoob at last years shoot out..

Also if there is lag but it is not noticable, is it really lag?? lol

There are other factors other than compression of air..
The speed at which the core or the intercooler can flow air, the path through which the air can take through the intercooler.
The Turbo is not compressing the air that is in the intercooler and therefore there is more to compress as the intercooler is after the turbo.. Therefore the turbo compresses the air and fills the intercooler.
Other thoughts are that you have a tmic full of air.. a small amount of air.. you floor the car and it draws all that air out of the intercooler into the engine and is then starved of air waiting for the turbo to push some more through.. and a vaccum is formed in the intercooler.. and a lag occurs in air reaching the engine.. fmic has more air in as it has a greater volume.. so you floor the car and the engine draws more air before there is a lag in air supply by which time the turbo is spinning a filling the fmic.. just a thought..

Theroies are fine but when in practice they don't appear that way.. which is wrong?

JGM

chucknorris

JGM: Blimey there's so much involved i think we need a boffin in a white coat, with a big forehead and a row of bic pens in his top pocket to tell us exactly what's happening under the bonnet with this one!!!!

As you rightly mention mine was just the theory behind it all and as you rightly say it's very rarely the same in practise because of so many other factors that are involved.

The only thing i would say is that with a bog standard uk car, you might find that lag may be more noticable (if at all) than compared to the likes of Harveys 500+ car. .... Who Knows...Only the Boffins at Tefal may be able to tell us! (please tell me you remember the Tefal adverts, or am I the only old git around here)

Jay m A

iTrader: (2)

Heres a theory that i made up

Think of flowing air in an IC like flowing water in a garden hose.

there is always air in an IC, whether the car is on boost, mid gear change or even switched off.

There is water in a hose, whether the tap is turned on or not. If you were to turn the tap on a hose full of water, would there be any time difference between the water coming out of the end of the hose, be it 1 foot or 50 foot long?

Its probably bollocks, young glasshopper

chucknorris

Your theory holds much water my young Padowan!


Now go and "wax on, Wax off" for an hour.

Jolly Green Monster

iTrader: (4)

How did you know I had a large forehead, wear a white coat with pens in the pocket and work for Tefal??

wrxtankie

I back up JGM an Del alright del, I fitted a dr 500 APS FMIC and noticed No more lag. If anything after the tek3 remap i think there was less.

Just my 2p


By the way cheers for the info b4 guys looks like im gonna change both MAF and the Lambda/O2 just to be safe.

Jolly Green Monster

iTrader: (4)

I have had a change of heart..

stick with the TMIC everyone (I want a chance of my car being quicker than somebodies!) LOL

JGM

Delboy2

LOL @ JGM

AvalancheS8

Water is more or less incompressible though, air isn't.
Makes a big difference.
The the main reason that the FMIC doesn't increase lag noticeably is that the volume of air being pushed through the system, and the speed at which it travels is huge. A 2 litre engine is drawing in 1 litre of air per rev on full throttle, which at 7000 rpm is 7000 litres per minute, or 116.6 litres pre second. Say your pipe work to and from the intercooler is 60mm dia, that 116.6 litres per second requires a that the air be flowing through the piping at 41.24 metres per second (about 92 mph), so maybe 2m of piping at most is going to mean that it takes the air .05 seconds to complete the loop. That's not going to be noticable. Even coming on boost at about a third of those revs, the time taken is still only .15 seconds, which still isn't going to be too noticable. In reality you won't have to wait for the air to make a complete circuit anyway, the pressure will rise through the system much faster than this, so the response time will be negliable.

vindaloo

Good theory but one slight problem. You can't squash water (compress it to a smaller volume). Therefore, you'll always get water out of a hose at the same time if you turn on the tap.

IMO whether there's any more power or more lag with an FMIC depends on the quality of the bits-n-bobs fitted. Is it fair to compare the effects of an aftermarket FMIC with a stock TMIC?

J.

vulnax999

iTrader: (7)

I have Si, but it IS now a STi V big shiny straight TMIC ... so less lag !!! So we may be near joint last!!

Actually, I now sustain boost longer and at higher pressure from my ickle TD04 turbo with the bigger TMIC as, I think, you said earlier ( and I thought was erm ... borrox ) as the volume of pressurised air is about 60% bigger and so stays at nearer full boost for longer at 7000 rpm in 2nd, 3rd, 4th ( 5th stays at 17psi for some reason! ) where as before with little slanty TMIC it would drop to under 10 psi in 2nd, 12 in 3rd, 14 psi in 4th, and only in 5th would it stay at around 15 / 16 psi ... at around 5000 to 6000 rpm ... private road of course.

back on topic...
Lag - the delay between requesting an action and receiving the response.
i.e. put foot down on accellerator and get a forward increase in accelleration.

More air to move in bigger volume pipework / FMIC rad, unless all this air is KEPT pressurised, more to move and so slower spool up, slower boost pressure rise, slower pressure to pressing the loud peddle.
See lag from big turbo's - large volume to compress and takes a finite time to do so before noticable effect ... compare to increased volume of air in FMIC vs TMIC.

Ever wonder why some FIMC kits major on short pipe lengths, reverse inlet manifolds on WRC and other cars... etc ... to reduce the volume of static, dead air that needs to get moving, on request.

<wipes brow, too late in evening for this !!>See ya at the Shootout JGM.!

siwrx

I have to say that personally I did notice a difference in lag when I fitted my FMIC.

I was running full decat, 17 psi boost, lightened flywheel, samcos,HKS SSQV, metal induction pipes etc so a few supporting mods for the boost. I fitted a HKS FMIC and instead of making full boost by 3500 rpm I now only push about 5psi until I hit 4,000 then the car goes like a train and imo pulls harder than it used to with the standard top mount.

However, just found out im misfiring a bit so will have to give you a second opinion once the car is running properly

Jolly Green Monster

iTrader: (4)

but Si has the car been remapped for the new intercooler??

If you take a car with a fmic on it all mapped for it and fit a tmic I think you will find you will have running problems and probably an increased lag too.

You cannot compare it if it is not been mapped for the new intercooler.

Presuming you still got the 2.2 in there so there must be some increase in fuel pressure to compensate or different ecu?

Simon