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View Full Version : Front mounted intercoolers....do they increase turbo lag?



mef
16th March 2004, 08:32
I don't know if this has been discussed in detail before as I am faily new on here but here goes:

I have been following some of the articles about FMIC's and the one thing that strikes me is the very considerable length of the pipework. Does this cause a noticable amount of turbo lag? I can see the point of doing it and would like to do similar to my rally car but I dont want to make it any worse than it is already!

WRC cars seem to have the turbo turned around such that the inlet goes to the turbo with a nice straight pipe that doesn't go under the plenum, also the outlet points over the plenum towards the front. Plus the throttle body is on the front of the plenum so the pipework is cosiderably shorter. Presumably they have done all this work to keep the pipework as short as possible?

I was lookig at Andy Barker's Hybrid Focus/Subaru rally car and he has copied this idea, turned the plenum around and lifted and turned the turbo. Is this a common mod on road cars too?

Anyone have any pictures of such conversions or comments?

Thanks,

Martin

bwhinnen
16th March 2004, 08:38
Calling Mr. Wallis tongue.gif

I know David did it as part of his HUGE thread on SN.

The shortest FMIC piping I've seen on a normal car is the PWR (http://www.pwr.com.au) for a classic shape WRX. A friend used to have one on his VF22 equiped car and from all comments it was not laggy and very responsive.

Also the thing I notice with mine (complete with stock TD04 turbo) is that the lag is the length of time the small compressor takes to fill the extra volume of piping. Generally less than 1/2 second.

Cheers
Brett

Andrew Carr
16th March 2004, 09:37
3-4th unhurried gearchange in Link logs, approx 5Hz sample rate:

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Count RPM MAP TPS OXY ETEMP VOLTS ZONE %FF ADV %WG KNK
55 6700 222 100 87 80 14.3 665 99 16 1 21
56 6900 222 52 88 80 14.3 670 99 16 1 30
57 6500 27 10 52 80 14.3 165 5 27 13 17
58 5800 11 10 50 80 14.4 155 4 25 10 29
59 5300 9 17 64 80 14.4 150 7 27 8 12
60 4800 135 96 4 80 14.4 445 39 22 6 8
61 4800 216 100 83 78 14.4 645 83 14 6 9
62 5000 238 100 88 78 14.4 650 92 14 3 6
63 5000 240 100 89 78 14.4 650 95 14 1 6</pre>[/QUOTE]This is with a fe TD05, Hybrid FMIC, Gruppe-S headers, 1.4bar midrange.

Andrew...

Simon_
16th March 2004, 10:26
Not all of them have long pipe work though..

Not a good picture...
http://images.fotopic.net/?id=3083885&outx=600&oq=0

Would you not be worried about smacking it being out the front?

Simon

nom
16th March 2004, 10:39
In short...
If you are running a tiddly turbo, and FMIC may increase the lag.
If you are running a big one, you won't notice the difference.
My swap from TMIC to FMIC occurred when I had something the size of a VF23 - I did notice a difference, which was that the car had a fair bit more go to it smile.gif It was a little less twitchy too - felt like a larger engine, I suppose.
In pros/cons, any additional lag is heavily outweighed by the additional performance/safety of the FMIC. IMHO, of course :D

Simon_
16th March 2004, 10:43
I noticed no increase in lag when I fitted mine..

Even with my crappy home made pipework smile.gif

I have slightly more lag now on the Link than when on the OE ECU but think that is as I don't have the boost control set up spot on yet.

Simon smile.gif

bwhinnen
16th March 2004, 11:10
This is also a 3rd-4th change, reasonably quick off and on the throttle. Mine are 7Hz logs. And as you can see it does take a tad longer with the "tiddly" turbo smile.gif

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Count RPM MAP TPS OXY ETEMP VOLTS ZONE %FF ADV %WG KNK
2583 6700 204 101 94 84 14 765 78 17 79 33
2584 6800 204 101 94 84 14 765 79 17 80 29
2585 6800 204 101 94 84 14 765 79 17 82 30
2586 6700 133 9 95 84 14.2 365 26 33 82 32
2587 6600 182 91 76 84 14.1 765 72 18 59 33
2588 6300 184 101 87 84 14 760 66 17 58 30
2589 5600 194 101 91 84 14.1 755 65 17 56 19
2590 5200 208 101 92 84 14.1 750 64 16 54 16
2591 5000 220 101 93 84 14 850 67 15 53 8</pre>[/QUOTE]Cheers
Brett

Adamantium
16th March 2004, 11:12
perhaps a picture of pats pipework would show up what can be achieved.

He is using the same intercooler as Simon above which has top fed end cans which immediately reduce pipe length.

Pat has also reverse his manifold and has a copy of my uppipe and down pipe which rotates the turbo to give a straight feed from the air filter and the compressor outlet points directly under the inlet manifold and then goes straight onto the drivers side input to the intercooler.

The exit from the intercooler bends round to run parallel to the cross member and intercooler core, then bends right through 90 degrees and with a little persuasion mates with the throttle body on the reversed manifold.

Total pipe length must be about 3 feet of that.

On another note, I think even with a small turbo the issue isn't that great. Consider the increased volume of the pipework (and dont forget the larger volume intercooler) and calculate how long it would take to fill as a function of the flow rate at a given pressure.

Plus it isn't a case of havig to pressurise the whole thing before you can notice any increase in pressure at the throttle body. The initial increased pressure at the turbo will be felt at the throttle body almost instantaneously as the pressure wave will travel through the charge at the speed of sound. Bear in mind this will be faster given the initial temperature of the charge, and faster still depending on what the residual pressure inside the system is.


There will be a delay, but I think it would be imperceivable side by side with a top mount, especially when standard turbo lag comes into play.

Fit anti lag, it would be a moot point anyway!

Andrew Carr
16th March 2004, 11:14
Yeah what they said.

With the FMIC the car feels torquier even off boost, my FMIC installation had far less airflow restriction that the TMIC it replaced which in combination with the constant flow of cold air makes the car feel stronger all round.

Andrew...

Simon_
16th March 2004, 11:21
Originally posted by Adam M:
perhaps a picture of pats pipework would show up what can be achieved.
He has it on there now then smile.gif

Picture would be wonderful..

Simon

nom
16th March 2004, 11:21
Hey Adam - you could have taken your explanation almost word for word from something I wrote on scabbynet once :D
So yeah - what he said ;)
There's a theoretical pause, but I think it's just that - theoretical. I sometimes have wondered why go to huge lengths to reduce the pipework length given the effort.v.effect ratio. Of course, it doesn't count if the engine is being made from scratch in the first place...

Andrew Carr
16th March 2004, 11:28
I need to setup my TPS again, Brett get 101, Steven Darley gets 103! but I am stuck at 100.

Its like their amp volume controls go to 11.

Andrew...

Adamantium
16th March 2004, 11:28
actually my original plan was to not reverse the manifold, but after seeing the intercooler from mark, I pretty much had to have one.

It was in my opinion what the pace should have been.

Far larger area in that it occupies all the height and all the width available as opposed to Pace's decision to use the RS500 intercooler core and just use different end cans. It also uses their own design of core which is meant to work incredibly well.

We tried it on the dyno and it did seem to make a hell of a difference, and while we couldn't at first attribute this to the intercooler because there was a simultaneous fixing of a leaking uppipe, once it was on boost it was still streets ahead of what was on there before.

Admittedly this could also have been as a result of using the HKS headers instead of H and S which had smaller primaries, but this difference was so drastic, I am not sure we can attribute it to that.

HKS rate their core to 500bhp, and while trout is already producing well over that consistantly, I am sure it is beginning to have a restrictive effect on the inlet path.

Next time on the dyno we will only be using the lateral intercooler, and I think only the H and S headers.

The headers may prove to be a mistake, but I am getting to the point where I know chasing too many horses is going to end up in tears.

Simon_
16th March 2004, 11:40
AndrewC,

Idle on mine is TPS of 12 and WOT is 101.. lol

It's a bit like an amplifier that goes up to 11!!

smile.gif lol

Adam,

Once I saw the pictures below I had to have one too.. smile.gif I want to reverse my manifold but it is just another step further away from standard that I am unable to make at the moment, due to money and the possibility of needing to return it to standard.

http://images.fotopic.net/?id=1766561&outx=600&oq=0

http://images.fotopic.net/?id=1766559&outx=600&oq=0

The no bumper cutting was a big plus too..

Simon smile.gif

Andrew Carr
16th March 2004, 11:45
I think everyone should have to fit a Hybrid FMIC at least once in their lifetime, it's an unforgetable experience!

How are your water temps with the Lateral FMIC/Radiator?

Andrew...

Simon_
16th March 2004, 11:59
AndrewC,

There is no doubting the price on the Hybrid is superb.. and although long the pipework looks to flow well.

Water temps have been very good and seem to sit between 84 and 88C.. and pops up to 90 in traffic.. I have the fans set to come on at 92C and have been watching temp closely at traffic lights etc and it seems to sit at 90 for ages before rising to 92 and fans come on..

Simon

Adamantium
16th March 2004, 12:06
sorry, I should have made it clear.

The lateral intercooler includes the rad which is taller but narrower to allow the take offs to the end cans to be in the right place. This pushes the whole assembly back (nowhere near as close to the headers and the cambelt cover as the pace). This means that the air con rad simply cannot fit in.

Since I was losing my aircon, I could remove the compressor, jiggle things round a bit run the pipework over the space that now creates and thus reverse the manifold.

I didn't have to do this but it opened up the perfect opportunity to reverse the manifold to reduce the pipe length, and the loss of aircon was the only thing stopping me from doing this before. That and a strong belief that the lenth of the pipes was really not an issue.

Anyway, having spoke with rally colin and suggestions from mark, it was decided that rather than losing the aircon compressor, I could lose the power steering pump and replace it with an elctric affair from a suitable peugeot.

I now require suitable bracketry so that all the important bits are in the right place, combined with suitable length belts.

The reversed manifold now opens up a large amount of space ofr a custom air con rad to go in, plus I intended to use the standard top mount as a template enabling me to provide adequate fixing locations for the new air con core.

This means get the best of all worlds.

mikeesingh
16th March 2004, 12:30
ive also fitted a lateral one to my car

http://images.fotopic.net/?id=3186522&outx=600&oq=0

will know what difference it has made over the pace one when pat tweeks map tommorow
i have upped fuel pressure for time being

only problem i had on mine was only being able to fit the one fan

mikee

mef
16th March 2004, 12:35
Thanks guys, all very interesting. I really like the idea of turning the manifold around, it seems like the obvious way to go. I noted that Andy Barkers Focus used an extension piece to move the turbo around and up, rather than a complete up pipe. Maybe a new fabricated up pipe would be the best bet though as its pretty horrible anyway!

Where do I get one of those intercoolers with the modified end cans from and how much? The WRC cars seem to have the pipe going in between the radiator and the slam panel. Will I have to fit a shorter rad then? I don't have any concerns with doing drastic mods/fabrication work as its a rally car and no air conditioning!

As regards the vulnerability of the I/C, well it's only the same as the WRC cars and ALL EVO's!

keep it coming!

Martin

Denmark
16th March 2004, 12:36
On this link you can see mine...

The pic is huge ,that why you can see it in this album.

http://img14.photobucket.com/albums/v41/Denmark/


Skassa

Simon_
16th March 2004, 12:43
Skassa,

Like the idea of moving the original rad back.. nice one smile.gif

Simon

mef
16th March 2004, 12:43
Looks like if I turn the manifold around I would have to move the alternator and power steering accross to the right a fair bit and remote mount the power steering reservoir too.

mef
16th March 2004, 12:44
Any pics of an installation with the reversed inlet manifold?

Simon_
16th March 2004, 12:48
You definitly have to move the alternator but I think it depends how you run air intake and other intercooler pipework as you whether the powersteering needs to be moved.

Have a look at Rannochs project thread..

Simon

mef
16th March 2004, 12:48
The other point in question is, is it worthwhile as I'm only using a 34mm restricted front entry TD05 turbo at present?

Simon_
16th March 2004, 12:52
Rannochs Pics (http://bbs.22b.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=2;t=000026;p=4)

Simon

Adamantium
16th March 2004, 12:57
will get pat to post his pics.

mef, which intercoller are you after with adapted end cans?

Denmark
16th March 2004, 13:04
Skassa,
Like the idea of moving the original rad back.. nice one
Simon


I have just ordered a carbonfiber plate to sit on top of the rad,so that the air only can come through the rad.

Skassa

Simon_
16th March 2004, 13:07
Good idea Skassa.. if there a gap between intercooler and rad fins? might be worth doing the same there?

I am thinking about doing similar only unfortunatly it won't be carbon fibre..

At least then you can cover that rusty old radiator tongue.gif

Simon

mef
16th March 2004, 13:12
I'm not really sure which intercooler I mean, I am refering to earlier posts and I dont know the makes etc? Please advise!

Martin

Denmark
16th March 2004, 13:20
At least then you can cover that rusty old radiator


Rusty ???.

Its just to make the air go in the right direction :D

Skassa

Simon_
16th March 2004, 13:26
lol.. I was kidding.. :D

I did for about 5minutes want to remove the complete centre section of my bumper to expose the complete intercooler to the incoming air..
then decide it was totally over the top for a road car and would no longer look so stealth.
;)

Simon

Adamantium
16th March 2004, 13:28
well obviously I think the lateral performance set up is a good one else I wouldnt have chopped in my hks for it, but the hks was still great and the same can be said for aps which I know people rate.

Have also not heard a bad things said about the hybrid one available through harvey's group buy, but I think in that situation, price was more an issue.

Didnt follow it closely enough to comment.

Personally I am not keen on the idea of spacing the radiator that far back, not unless you box it in relative to the intercooler.

Denmark
16th March 2004, 13:57
Personally I am not keen on the idea of spacing the radiator that far back, not unless you box it in relative to the intercooler.


But there is as it is now no problems with the watertemp,from the linklog,its around 84-86degrees when going for it,that used to be 82-84degrees before the frontmount came on.

Skassa

CarlosH
16th March 2004, 14:17
Originally posted by mef:
The other point in question is, is it worthwhile as I'm only using a 34mm restricted front entry TD05 turbo at present? uhmmmmmm I don't think you will need a huge intercooler for a 34mm restricted car, especially when the peak power will probably get is 320bhp.
My experience is that FMIC do help a lot, and let you have more power/torque, but on a rally car o hillclimb car it will depend on the type of event. If it is very twisty you will definetly feel the xtra lag ..... what you can do is also to have ALS enabled that way there will be virtually no lag left.

Carlos H.

Fuzz
16th March 2004, 17:36
Originally posted by AndrewC:
I think everyone should have to fit a Hybrid FMIC at least once in their lifetime, it's an unforgetable experience! :eek: :eek:

Could you explain this quote further please as it is one of these that a customer has bought for me to fit to his Rover...


Andy

Andrew Carr
16th March 2004, 18:48
Can't comment on anything but the impreza kit, but it's hard work: http://bbs.scoobynet.co.uk/showthread.php?t=295624

Andrew...

harvey
16th March 2004, 20:44
In answer to the original question, I think that stories of increased turbo lag caused by FMICs are part of established Scooby fooklore and unfounded. There will be a marginal increase but hardly noticable and as already stated the benefits are very noticable.
I guess you could work it out. Take the flow rate of the engine at your chosen RPM and compare it with the increased pipework and FMIC air capacity over the O/E set up.

CarlosH
18th March 2004, 04:27
Harvey, your reply sounds about right, but for competition purposes unless you can get a setup with much less pipping than that of APS (probably rotated inlet manifold etc.) then there would definetly be an increase in reaction time of the throttle. IIRC Andy F. with his very short FMIC pipping design still argued that for drag racing he lost some time when changing gears when compared to his TMIC setup.

Would be interesting to see how would the APS silicone pipes handle, very aggressive ALS ;) .

Carlos H.

johnfelstead
19th March 2004, 00:13
i would try and work out the volume of the WRC intercoolers being used now Martin, i would expect that is well researched with regards to performance with a 34mm restricted engine.

CarlosH
19th March 2004, 01:24
John IIRC the FMIC of the 2003 Impreza WRC is smaller (in volume) to an APS unit ..... it is possible to check this out by just comparing pics. But the pipping is waaaaaaaaay shorter.

harvey
19th March 2004, 18:46
Carlos: You are right in that there must be an increase in lag because there is a bigger volume of air but in my experience on five or six Scoobies to date any lag increase is so small that it is barely perceptible whereas going to a bigger turbo it is very noticable by comparison. As an aside you adjust to it and instinctively and have your foot down half a second earlier or whatever.(referring to the bigger turbo)

The WRC FMIC is noticably smaller than the APS but remember what the WRC is about. Lots of differences to a road car that has to fuction satisfactorily for thousands of miles. Everything is minimalist. The car runs on a restrictor, "only" has 300 odd BHP and weight is the enemy so no point having an intercooler that can deal with 400 BHP.

No idea how silicone pipes would stand up to anti lag but they are OK for road use if fitted with care and thought. Slight flex or expansion of the pipe is not an issue. About 33K mls on mine with one mishap early on which was down to bad fitting by me and coming in contact with the headers. A temporary repair around midnight in Swindon and Bob's your uncle if you know what I mean. Lasted several hundred miles until I repaired it properly. No thanks to APS who wanted around 200 for a single pipe.

PS. The 2003WRC is about 50kg lighter than the classic shape WRC was and has to have lead weights added.

CarlosH
20th March 2004, 04:48
Harvey, if you know that the WRC FMIC is noticeably smaller than the APS unit then you are just confirming what I was trying to tell. Martin(MEF)'s car is not a road car, it is a rally car with a 34mm restrictor ;) ..... therefore like you say there is no point for him in having a huge intercooler when the most power he will probably get is 320bhp. I would recomend him to go for a better/bigger TMIC than going for a FMIC, unless he has a intercooler custom made, much smaller than the common units (HKS, APS, Hyperflow, etc.) and with very short pipping ..... $$$ .....


I really doubt that the fairly long silicon pipping of the APS kit would handle aggressive ALS, you would have to look to a pipping setup more similar to that seen on WRCs.

mef
20th March 2004, 06:10
OK, I get the point, if I was to stay TMIC, what should I fit, one from a new age Sti maybe?

Martin

Andrew Carr
20th March 2004, 10:02
Martin,

You should have a couple of emails from me.

As I said the other day, WI in conjunction with a free flowing TMIC is an option.

Andrew...

CarlosH
20th March 2004, 13:35
like on the old Group A days ..... TMIC plus methanol injection :D

Carlos H.

johnfelstead
20th March 2004, 16:45
Martin, the TMIC setup on the current Spec C is good for more power/torque than you are ever going to see. I wouldnt go for an aftermarket TMIC, they weigh a ton and will make heat soak on the start line to a stage worse due to mass increase and dont help your C of G either.

harvey
20th March 2004, 17:44
Wood a picture of the WRC 2003 set up help anybody?

Simon_
20th March 2004, 21:07
Originally posted by harvey:
Wood a picture of the WRC 2003 set up help anybody? Any picture would be great to look over, I am becoming a trainspotter for Scoob engine bays! lol I think I have seen the 2004 but not 2003, different??

Simon :D

CarlosH
22nd March 2004, 03:06
http://www.johnfelstead.co.uk/rally/wrc/monte_carlo_2003/images/DCP04698.JPG

http://www.johnfelstead.co.uk/rally/wrc/monte_carlo_2003/images/DCP04701.JPG

John please let me know if you want the pics not to be used .....

Carlos H.

mef
22nd March 2004, 08:07
Only a tiny little FMIC then on the WRC cars then as they only produce 300Bhp!

Simon_
22nd March 2004, 09:16
Thanks Carlos smile.gif

Floyd
22nd March 2004, 13:02
Only small but with the ducting and venturi effect, it'll be as efficient as a larger more obstructed one?

F

mef
22nd March 2004, 20:48
I was joking! It looks huge!

Floyd
23rd March 2004, 13:15
It only looks as if is on the top half of the grill.

F

Simon_
23rd March 2004, 13:18
Yeah but the APS is only the bottom grill in the bumper.. obviously we are not taking depth into account etc..

Simon

jim.....
23rd March 2004, 15:11
The intercooler does only use the top section of the grill, but what you have to remember is that all the cold air hitting has to go through it, as its cowled in so no air can escape sideways, and with the duct going on to the bonnet, the pressure drop within it will increase air speed through the FMIC.


Jim

CarlosH
24th March 2004, 13:54
WRC engine ;) :

http://www.i-club.com/gallery/data/504/3091tas2003_93_.jpg

Andrew Carr
24th March 2004, 14:08
You've gotta love the EJ20 - from any angle it's an ugly mess!

Andrew...

Simon_
24th March 2004, 14:11
Originally posted by AndrewC:
You've gotta love the EJ20 - from any angle it's an ugly mess!

Andrew... It sure is isn't it.. I still remember looking under the bonnet for the first time and just seeing masses of hoses and wires..
and I remember saying "well that's where the oil goes.. which is all I will be doing on this car.."

How wrong was I!! ;) :D

Simon

jim.....
24th March 2004, 14:30
Wish mine was that clean! even the car outside it isn't that shiney!


Jim

Simon_
24th March 2004, 14:35
Originally posted by jim litten:
Wish mine was that clean! even the car outside it isn't that shiney!


Jim It would only get dirty again smile.gif

Simon