FMIC Lag....
26 February 2011, 03:28 PM
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FMIC Lag....
Looking to upgrade to a Front Mount next month and i was wondering about the amount of lag i'll get compared to the TMIC. My car has a TDo5 Turbo which is a little laggy.
Roughy, when will full boost kick in? My Turbo is a TD05 16g
Roughy, when will full boost kick in? My Turbo is a TD05 16g
26 February 2011, 03:48 PM
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Once pressurised you should not see much of a difference (with a decent system with little pressure drop).... it's that initial response that can be hindered (if at all).
26 February 2011, 04:06 PM
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Cheers Shaun, saw your car at a WMI meet last summer. Think you were pushing 600bhp. Not that im looking for 600, but what intercooler are you using?
26 February 2011, 05:08 PM
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Increased lag on a decent FMIC, properly mapped is an SN myth!
But it is important to decide whether you NEED the FMIC at the current/desired level of tune.
Get a quality piece of kit (e.g. Hybrid, perrin or APS) have it fitted well mapped properly and you'll be hard pushed to tell the difference in lag. What you will notice is the extra omph!
But it is important to decide whether you NEED the FMIC at the current/desired level of tune.
Get a quality piece of kit (e.g. Hybrid, perrin or APS) have it fitted well mapped properly and you'll be hard pushed to tell the difference in lag. What you will notice is the extra omph!
26 February 2011, 05:18 PM
#7
The pipework on a FMIC is much longer than on a TMIC and more pipework means more lag/worse throttle response (some people notice it, some don't, but it is there).
On a MY94 it can be a pain fitting a decent (STi8 on) TMIC and you might be better off with a decent FMIC.
On a MY94 it can be a pain fitting a decent (STi8 on) TMIC and you might be better off with a decent FMIC.
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26 February 2011, 06:43 PM
#10
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That car has gone now to a new owner, but it used a Hyperflow MONSTER Intercooler set-up. It is a very good FMIC, especially for the higher power builds..... but it aint cheap.
I now own another JDM, but this time a Hawkeye STI. This retains the TMIC and is producing 400bhp. I might change to a FMIC in the future, but only when I need to... currently I don't.
Regards,
Shaun
26 February 2011, 07:07 PM
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From my experience, front mount intercoolers on classics do give a noticeable lag increase.
It might be more difficult and expensive but but I'll be fitting a v5 iirc manifold and an sti7 tmic.
It might be more difficult and expensive but but I'll be fitting a v5 iirc manifold and an sti7 tmic.
26 February 2011, 07:15 PM
#12
ive gone from a sti top mount to a front mount,and to be honest you do get a bit of lag lowdown,but nothing to talk about really,marginal at least.but as others have said depending on how far you intend to take the car bhp wise the topmount does a good job especially the sti one,but if your looking big power future proof with a quality frontmount.
26 February 2011, 07:52 PM
#14
but because i am very sensitive to the low down pull i noticed that the throttle was not as snappy low down but as i said before very marginal but it was still there.
26 February 2011, 07:56 PM
#15
and further more i have been to darlington to get harveys uppipe and headers that was one of my first mods.i drove all the way from south east london croydon with my wife to get the work done and meet the legend,and very nice and friendly gent he was.
27 February 2011, 12:09 PM
#16
Hope you Jenny and family are good.
With an efficient core and proper mapping lag from an efficient FMIC installation is very much non existant. The cause of lag is usually something else.
With an inefficient core with a high pressure drop or poor pipework you will notice the lag. An efficient tube and fin core is the one to go for, such as Hybrid. As regards the increased pipe run and intercooler core size you can do the calculations for yourself and compare the increased pipework on the front mount intercooler installation with that on the top mount and then look at the engine air consumption. Even pressurising from a vacuum situation at low RPM, a worst situation scenario, say from 2500 RPM in vacuum, on to boost and the lag is only a fraction of a second. Obviously further up the rev range the lag factor decreases. The benefits from a front mount intercooler beyond a certain level far outweigh any minor deficits.
Maybe Pat could come along and do the calculations if he can be bothered because he has done them so many times before they are old hat. Do a search and you will see the calculations I have done separately.
If you want to have an alternative view it matters not to me but if you actually own a car with an efficient intercooler set up you need to be looking for the causes of any lag and not just putting it down to your intercooler (unless it is inefficient or bar and plate).
With an efficient core and proper mapping lag from an efficient FMIC installation is very much non existant. The cause of lag is usually something else.
With an inefficient core with a high pressure drop or poor pipework you will notice the lag. An efficient tube and fin core is the one to go for, such as Hybrid. As regards the increased pipe run and intercooler core size you can do the calculations for yourself and compare the increased pipework on the front mount intercooler installation with that on the top mount and then look at the engine air consumption. Even pressurising from a vacuum situation at low RPM, a worst situation scenario, say from 2500 RPM in vacuum, on to boost and the lag is only a fraction of a second. Obviously further up the rev range the lag factor decreases. The benefits from a front mount intercooler beyond a certain level far outweigh any minor deficits.
Maybe Pat could come along and do the calculations if he can be bothered because he has done them so many times before they are old hat. Do a search and you will see the calculations I have done separately.
If you want to have an alternative view it matters not to me but if you actually own a car with an efficient intercooler set up you need to be looking for the causes of any lag and not just putting it down to your intercooler (unless it is inefficient or bar and plate).
27 February 2011, 01:39 PM
#17
hi harvey,hope your in good health,jenny says hello.right back on topic,the intercooler i got is a perrin that my wife bought for a present for me,and it works well,but i just feel that low down the car just does not feel as sharp on the throttle as when i had the top mount.maybe its all in my head or i am just being pickie, either way its proberly nothing to talk about really its just slight.but it does perform well on the temps,which now i have the bigger turbo plus bigger injectors and am running more boost works fine.
27 February 2011, 01:55 PM
#18
If a TMIC is changed out for a FMIC and mapped with no other changes why would someone need to meddle with the headers/up-pipe to counter the lag that you say simply doesn't exist?
Also, why would someone like Cosworth on their completely reworked £50k Cosworth Impreza also choose a TMIC over a FMIC? And again, Litchfield.
So does a FMIC increase lag? Of course it does, like I said from the outset, some people will notice it and others may not, it's is still there though.
For the OP having a early classic, like I said a FMIC may be the better option.
Not sure what it is about the topic that turns this into such nonsense everytime.
27 February 2011, 04:59 PM
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I noticed increased lag while running a FMIC. I put my top mount back on and was suprised at the increase in throttle response. However, my car had not been mapped for it so that may have been an issue, i was only running a PP chip.
27 February 2011, 06:47 PM
#21
As usual, people here are confusing 'throttle response' with 'lag'. Swapping out a TMIC for a FMIC does result in a slightly less sharp throttle response due to increased pipework. (There's an old post on SN where Andy Forrest produced some calculations suggesting an extra 0.3 seconds in response time when pressing the loud pedal). As has been said on here, some notice this reduction in sharpness and some don't (I did). However, there's no reason why a good FMIC set-up should increase 'lag' - ie the rpm level at which the turbo spools.
27 February 2011, 08:40 PM
#22
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So let's just ignore that actual facts of increased pipework lengths. Lets also ignore the numerous people that say they do notice the increase in lag after fitting a FMIC and then the remaining people that says it makes "little" difference.
If a TMIC is changed out for a FMIC and mapped with no other changes why would someone need to meddle with the headers/up-pipe to counter the lag that you say simply doesn't exist?
Also, why would someone like Cosworth on their completely reworked £50k Cosworth Impreza also choose a TMIC over a FMIC? And again, Litchfield.
So does a FMIC increase lag? Of course it does, like I said from the outset, some people will notice it and others may not, it's is still there though.
For the OP having a early classic, like I said a FMIC may be the better option.
Not sure what it is about the topic that turns this into such nonsense everytime.
If a TMIC is changed out for a FMIC and mapped with no other changes why would someone need to meddle with the headers/up-pipe to counter the lag that you say simply doesn't exist?
Also, why would someone like Cosworth on their completely reworked £50k Cosworth Impreza also choose a TMIC over a FMIC? And again, Litchfield.
So does a FMIC increase lag? Of course it does, like I said from the outset, some people will notice it and others may not, it's is still there though.
For the OP having a early classic, like I said a FMIC may be the better option.
Not sure what it is about the topic that turns this into such nonsense everytime.
o my good lord, you still pedalling that rubbish? lol
28 February 2011, 08:14 AM
#24
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mainly because you havn't quantified your responce, i can't be arsed to go over ground that has been done twenty gazillion times, but here ya go if you realy want me to say the same thing again.
for those that don't know his information is based on a calcultaion that was done by andy forrest about 6 years ago. the calculation makes assumptions that in real life are so far off the mark that its unreal, eg its a static revs that the car will change gear at 3k. most cars i know are roughly 6000rpm when they change gear, and at 3k arn;t even on full boost. It also assumes that there is no pressure in the system at all, which there never is. there fundamental to working out the timing and send the answer so far off track that i think you need a map and satnav to get back again.
you constatntly harp on about front mount lag, yet folks who have gone from a top to front mount are telling you over and over they have not come across the same issue, yet you ignore them and reference those who have had issues even if corrected later due to other things.
you keep mentioning 'cosworth don't do it' 'why havn't subaru done it', the simple answer is cost. you'd have to redesign all the intake pipework as well. On a side note the subaru rally cars do have them in a changed position,
i guess you need to go and explain to them about it as well, cos i can;t seem to find a wrc subaru with a top mount :s.
have i missed anything or have i got to go back and link the previous threads?
28 February 2011, 10:22 AM
#26
I though I would check this out in my logs to get some actual figures .... a full throttle gear change from 3rd to 4th, from the time that the throttle is full depressed after changing gear to the time manifold pressure has gone from vacuum to full boost 1.8bar takes about 400 hundreds of a second with my APS FMIC and an MD321T. It feels pretty much instantaneous on the road.
I have found that getting the right low load timing has a much greater influence on how sharp the throttle response feels (i.e. if you are running too little timing, you are not using the available energy from combustion fully and this will make the car feel sluggish). If the car is well mapped throttle response should be good regardless of whether a FMIC or TMIC is being used.
I have found that getting the right low load timing has a much greater influence on how sharp the throttle response feels (i.e. if you are running too little timing, you are not using the available energy from combustion fully and this will make the car feel sluggish). If the car is well mapped throttle response should be good regardless of whether a FMIC or TMIC is being used.
28 February 2011, 11:50 AM
#28
Alcazar: Not sure what thread you're reading? Maybe a visit to Specsavers is in order 
Tidgy: WRC cars and road cars are completely different. You will also note that on the WRC cars they have done all they can to minimise the pipework length, nothing like most FMIC that people fit to their road cars. Do you really think Cosworth skimped on a FMIC kit?! Have you seen the spec? I daresay that TMIC they use is more expensive than most FMIC kits anyhow.
I think you will find that my first post is accurate and answers the OP's question. Alcazar's statement that it is a "Myth" is incorrect and won't find any reputable tuners agreeing with him.
Even a FMIC salesman will tell you that there is a difference in throttle response between a TMIC and FMIC, it's just logical. Nobody in the know is going to deny that there isn't.
Tidgy: WRC cars and road cars are completely different. You will also note that on the WRC cars they have done all they can to minimise the pipework length, nothing like most FMIC that people fit to their road cars. Do you really think Cosworth skimped on a FMIC kit?! Have you seen the spec? I daresay that TMIC they use is more expensive than most FMIC kits anyhow.
I think you will find that my first post is accurate and answers the OP's question. Alcazar's statement that it is a "Myth" is incorrect and won't find any reputable tuners agreeing with him.
The pipework on a FMIC is much longer than on a TMIC and more pipework means more lag/worse throttle response (some people notice it, some don't, but it is there).
On a MY94 it can be a pain fitting a decent (STi8 on) TMIC and you might be better off with a decent FMIC.
On a MY94 it can be a pain fitting a decent (STi8 on) TMIC and you might be better off with a decent FMIC.
28 February 2011, 01:13 PM
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8000 rpm @ 2 bar of boost = 1 x 8000 x 3 litres of air a minute !
Or 2.4 cubic metres of air !
Or around 85 cubic feet !
dunx
P.S. Using a TMIC on a built motor is O.K. because the engine is strong enough to allow the compromise to work... I'll stick with my Hyperflow "Monster" TA very much !
Or 2.4 cubic metres of air !
Or around 85 cubic feet !
dunx
P.S. Using a TMIC on a built motor is O.K. because the engine is strong enough to allow the compromise to work... I'll stick with my Hyperflow "Monster" TA very much !