Been doing some primary school maths (but cheated and used a calculator).

1900cc = 0.0671 cubic feet.

Assuming 1.5 bar boost, total air consumed = 2.5 times that (including the 1 bar atmo.)

Engine revs to 4500 rpm. However each cylinder ingests air every other revolution, so half it.

Multiplying this out, I get 377CFM flow required to run the engine at 4500rpm.

Is there anything wrong with this assumption? Why is it likely to be high or low (or just plain wrong)?

J.

Not at home right now, but I'll have a look later as I have all the calcs on my home PC

What are you trying to calc and why?

There are several variables not considered in your calcs, namely:

Altitude / air pressure

Humidity

Diesel efficiency - I guess you've used petrol engine efficiency ratio of 85% rather than a more realistic 60% for a diesel (I could work that out for you if you let me know things like compression ratio and expansion ratio ) IIRC56% is the ideal for a diesel, but for my calcs I've used 60% to err on the side of caution

Right, to my calcs:

CFM for normally aspirated:

(cubic inches x rpm x 0.5 (for the cycles on a 4 stroke) x efficiency) divided by 1728 (to convert to cu/ft)

goes to (115.701018315 x 4500 x 0.5 x 0.6)/1728

goes to 156196.37472525/1728

Gives 90.39142055859375 cfm

Right, now on to flow rate under boost (leaving out volumetric efficiency )

airflow rate = pressure ratio x basic engine cfm

goes to airflow rate = 2.5 x 90.39142055859375

Gives airflow rate = 225.978551396484375

Call it 226cfm

HTH

Trying my best to understand the terms going on up there.... But i'm afraid i've fallen at the first hurdle!

Which bits? I'll try and explain......

I sincerely hope it's not all that complicated or I'm lost...

...but Hey, I figured out where you got you 115ci's from It's my 1900cc's of 1.9litre diesel engine. I had assumed that there'd be losses in filling the cylinders. 56% is an eye opener though.

Ignoring the engine (!) I'm trying to figure out whether a 6"x4" chargecooler is gonna be big enough cool a remapped 1.9 PD 130. Idea being a tiny chargecooler in the right place will eliminate the extra lag I would see fitting an FMIC but prevent heatsoak.

www.chargecooler.co.uk is where I started looking. Have read some stuff on SCN and Pistonheads. I think trying to place the MAP sensor is where it'll get a) expensive and time consuming.

J.

The efficiency is the efficiency of the engine at burning the fuel.

The bit about the 0.5 is the same as you mentioned "However each cylinder ingests air every other revolution, so half it."

The RPM and the cubic inches you already knew

So it's simple really the only bit you were missing was the engine's efficiency.

As for the second part, again, fairly straightforward and you'd got that bit anyway.

Re the charge cooler, what do you want to know? eg I specced my intercooler based on a peak power rating of 450bhp

< Patronising git > You done the injector calcs for the car yet, or do you need a hand with them as well? < /Patronising git >

Just re-read your last post, what power you looking at? I'll calc the charge cooler size for you when I get a chance

I went a long way down the charge cooler ( it will need to be a lot bigger than 6 x 4 ) and in the end was advised it was the wrong way for a diesel by Badger bill, the well known Seat lunatic and tuner, but don't let me put you off, i settled for a BFOFMIC cheaper in the long run in kit form

To throw in yet another confounding variable - which I hope someone here can work out mathematically - what if you boost the intercooler's heat sink properties with a water mister (not sprayer)?

This is the question I would like answered:

Can an OEM SMIC fitted with a mister match a FMIC on its own? If it's even just nearly as good, it's a far cheaper option.

I would hazard a guess that it may even be superior to merely just increasing IC volume/ core mass if all an intercooler is is merely a heatsink:eek: . (Heresy!!! He speaketh against ye holy FMIC!!!! Burneth him at ye stake!!!! )

The high energy value of the latent heat of evaporation of water gives it a major effect on cooling.

See relevant data/graphs testing the effect via VAG COM on an Audi A4

on:http://www.audiworld.com/tech/eng22c.shtml

main article on: http://www.audiworld.com/tech/eng22.shtml

I have just received the bare-board intelligent controller, larger washer tank, headlight washer pump and will try to fit it all this weekend if I can. With temps here around 42 deg C, I'm anxious to see how it works out:D .

If this is indeed anywhere as good as a FMIC, it can save a major amount of money!

I welcome any comments, please

Cheers

Bas

Better still cool with Nos or methanol.

This is the question I would like answered:

Can an OEM SMIC fitted with a mister match a FMIC on its own? If it's even just nearly as good' date=' it's a [i']far[/i] cheaper option.

The high energy value of the latent heat of evaporation of water gives it a major effect on cooling.

Last year I ran a SMIC mister rig using the Autospeed nozzle - looks like a similar setup to yours except I built my own timer/controller.

Under UK conditions, it produced a measurable drop in intake air temperature (from 92

charge cooling should be mentioned in terms of B.F.O with regards to FMIC and cooling.

An FMIC will only cool the charge air down to ambient temperature (42

surely a fmic could cool the boost air to below ambient temp due to (for want of better words) wind chill?

sat here at my computer in hot weather i can blow over my hand and it cools it temporarily' date=' i assume this is because the moving air is absording the heat energy being disapated by my hand.

or i could be completely wrong [/quote']

It could be because you're sweating and blowing air over your hand it to evaporate

The efficiency is the efficiency of the engine at burning the fuel.

The bit about the 0.5 is the same as you mentioned "However each cylinder ingests air every other revolution' date=' so half it."

The RPM and the cubic inches you already knew

So it's simple really the only bit you were missing was the engine's efficiency.

As for the second part, again, fairly straightforward and you'd got that bit anyway.

Re the charge cooler, what do you want to know? eg I specced my intercooler based on a peak power rating of 450bhp

< Patronising git > You done the injector calcs for the car yet, or do you need a hand with them as well? < /Patronising git >

[/quote']

I want "up to 200bhp" on my Fabia. Initially, I'll settle for a custom remap and 175-180ish. However, I've read that even with Pikey mods, the SMIC may not be up to it.

I think that chargecooler, plus reasonably large chargecooler radiator could be the answer I'm looking for. Main gripe/worry is setting it all up and wondering how loud/whiney the pump will be.

One of the great things about the car is the instant, on-tap grunt should I plant my boot on the throttle at somewhere around 2500rpm. I don't want to lose this.

Pistonheads article: http://www.pistonheads.com/gassing/topic.asp?p=4&f=66&t=268120&h=0

PWR website

http://www.pwr-performance.com/intercooler.htm

I seem to have misread something though, their core is 6"x4", with the "cones" on it's more like a foot long... - 11.75" Still not huge though...

J.

My understanding (limited ) is that you'd need the chargecooler radiator where the FMIC would normally go. The benefit would be that the chargecooler would be a much shorter intake air route I suppose.

Is there enough room to actually fit the charge cooler itself?

FMIC definitely has a positive impact especially at the moment with 30+ degrees C temperatures, much better than SMIC based on comparison with last year's hottest days where it was heatsoaking like mad.

Venting the arch is by far the cheapest option of course, and I reckon for value for money it's great.

If the charge cooler causes the air path to be reduced I'd imagine it would improve the responsiveness a little (post-custom-map).

Definitely interested in the outcome

I think trying to place the MAP sensor is where it'll get a) expensive and time consuming.

J.

How about leaving the smic in place with the map sensor fitted and fit the chargecooler somewhere else in the pipe work. Saves trying to figure out a way of fitting it plus you have the addition cooling of the smic.

So what size radiator are you looking at for the pre rad?

How about leaving the smic in place with the map sensor fitted and fit the chargecooler somewhere else in the pipe work. Saves trying to figure out a way of fitting it plus you have the addition cooling of the smic.

Wonder if it could be done? Have to figure if it will fit together with piping for radiator/pump etc.

I e-mailed AVT, he reckons the 6x4 will do the job.

Whatever the outcome, I've got to whip off the wheelarch liner etc. to see if the i/c will fit, so I may as well get down and pikey whilst I'm at it. Apparently a 2 litre coke bottle is a good approximation of the shape of the CC.

J.

If the chargecooler is the size of a 2litre coke bottle will it fit inplace of the smic? Might be tight.

What else is needed for a cc? I take it the cc itself. Radiator to cooler down the water. Water pump to pump the water and piping. Anything else? I take it all the water is stored in the radiator or does it need a seperate water tank?

Anyway sounds like a good idea as long as the radiator is big enough to keep the water cool under hard runs.

i would have thought a master cylinder would be needed otherwise you will get air in the rad.

i would have thought a master cylinder would be needed otherwise you will get air in the rad.

Coke bottle or slightly shorter than... They quote 11.75" but there's likely to be a requirement for silicone elbow(s) to route the pipework properly.

Other items needed - high flow pump, 3/4" coolant hose, extra radiator... Don't know what I'm going to do about the rad. yet. Though if a forge FMIC fits, an extra rad. will definitely fit.

Alternative that's been rejected is to use the "bong" approach :eek: to cooling down the the CC water.... As seen on several computer overclocking sites...

J.

the rad for the CC will be significantly smaller than the coolant rad, probably more like the air-con rad.