standard air box clearances, how much cold air really gets to it.

[Turbo_Steve]

It might be, but the potential for hoovering up a puddle at that height is significantly increased, brad!

And yes, 30mph, sorry - all I can think of is mpg at the moment. My fuel bill is the same size as most peoples mortgage payments: they're really shocked when I tell them!


Dave - nothing wrong with a theory at all, and big props to you for even considering all this.

With the turbo, bear in mind that the radiant heat being transferred between the two halves is comparitively microscopic compared to the conduction through the metal middle of the turbo!

Also don't forget that the compressor side itself actually gets hot due to the compression process....it's generally just easier to intercool the charge afterwards.

I'm mainly interested in keeping the whole back of the engine cooler, irrespective of turbo performance. Cooling down the exhaust housing isn't going to make a significant difference in performance terms compared to allowing the engine to run cooler, allowing less fuel and more timing.

You need to be worrying about having a "perfect" exhaust design (which is, at the very least, a seperate exhaust for each turbo with a link pipe midway) long before exhaust housing cooling becomes an issue. That said, you could always wrap the exhaust side in a turbo blanket to keep the heat in.

I'd rather cool the whole lot, and run higher EGTs, though - you're not trying until you melt an exhaust manifold

[Davezj]

i had thought about cooling the back of the engine bay down a bit by fitting the 2 motorbike radiator fans (which are quite conpact) to a metal fram suspended off the fire wall and blowing down. the rubber seal is off the back of my engine bay so the fans should draw air in from that region as well as hot air from the top of the engine bay, and blow it across the rear exhaust manifold and turbo and blow it out the bottom of the engine bay and once the air flow has been established by the fans, maybe the draw from under the car with act like the draw on a coal fire when you first get it going with a sheet of news paper above the opening. but maybe that is just wishful thinking.
i think the fans would certainly help with the cooling of the rear.

[Turbo_Steve]

It's a thought, but I don't really think that you'll get enough flow through the back on the bonnet - IMO you'd need have an inlet on top of the bonnet (scoop for preference, but UGLY yuk) or a mesh vent or similar. With a scoop you should get downward +ve flow.........with a vent I couldn't be sure without trying it - I'd imagine that it should draw air upwards as it crosses the bonnet.

My thoughts were in terms of having a wide slot across the rear of the bonnet (about the width of the washer jets) that either dropped downwards, or simply spanned the width with a grille (Mercedes E class bonnet?) The problem here is the negative pressure under the car can make it difficult to establish airflow in this direction.

Alternatively, borrow heavily from subaru (look at the old Legacy single turbos) and have a teeeeeny scoop in the bonnet that directs airflow straight onto the turbo-charger.

This would have the benefit that you could put a fan into the assembly to keep air flowing when stationary.

[Davezj]

hmm, i will have to have a bit more of a think about the turbo cooling.

but i have decided what i am going to do about the air intake, a bit of foam tape and a bit of cutting and all will be done, for the better hopefully.

[fassi1]

I thought I'll refresh this thread.
I was looking at the air intake funnel the other day thinking that I should meassure the cross section of its inlet and outlet.
Inlet cross secton of the funnel is about 4 800 mm2 which is almost identical to the MAF outlet cross section.
Outlet cross section of the funnel is about 6 800 mm2 which is a lot more than its inlet cross section.
I wonder if funnel inlet can be restrictive for the stock induction especially running increased boost and having supportive mods like 3" exhaust and larger intercooler.
Has somebody ever tried to compensate smaller funnel inlet by adding an extra duct before air filter fed somwhere from the fog light area as mantioned by @Kenneth

" It is possible that the funnel does impede induction, however I haven't seen that proven and there are many of us with very good power figures who use the OEM airbox setup. It could be more cost effective to cut into the airbox before the panel and add another duct into a cold air position low in the wheel well. An added benefit of keeping the upper funnel is that you wont hydraulic your engine easily. "

in this thread
http://www.clubvr4.com/forum/showthr...t=maf+diameter

[exevoowner]

had looked at this for ages and looked at the differance in the pfl and fl grills as in daves pictures i thought about adding some kind of shield to the open section at the front but have not tryed any mods yet
I have seen the ARC airbox runs a open filter so as stated the cold air under the bonnet is not a big issue

[fassi1]

I just wonder if inlet cross section of the funnel was as big as its outlet, would that increase the air flow even if OEM inlet cross section of the funnel is as big as MAF's outlet?

[Davezj]

personally i think the biggest restiction to the air flow is the area between the underside of the bonnet and the slam panel just in front of the the snorkle

see picture 14 in the first post, the one with the key in it. please bear in mind that the the normal bonnet stay with it foam insulation bit that sits directly across this area. blocking it off even more.
take a look at your area infron tof the snorkel.

i think the only way to change this restiction is to cut metal from either the underside of the bonnet or from the slam panel and reform it.

but after all that, i don't know if this area does cause a restriction or not.

you would have to work out the max flow of the turbos, then the cross sectioanal area of the smallest area the air has to flow through. then work out the velocity the air would have to travel at to allow the turbos to flow there max value.

then do a test to see what vacuum level you would have to create to suck that level of air flow through the restriction.


but rather than doing that you could just put a big pipe in place of the snokel and run it down the front of the gear box to get cold air in there.
then run the car and see if makes a difference.
if there is a restriction, then i would assume that the restriction would show up most as the turbos flowed there max air flow value. if there is no difference at this point, you can only assume that you have not removed the biggest restriction in the system. and vice versa if it does make a difference. i say you would have to do the test without any boost control due to the possibility that the only effect you get is a slighly higher ultimate boost level, and with boost control fitted you are pegging the ultimate boost level back already and quite significantly.

now for what the difference is this can only really be seen on a boost gauge. If you do not have a dyno to hand to play on. but you would have to have no boost control used and just allow the turbos to spin up as quickly as they want to and create as much boost as they want. but you will have to do this before and after the snorkel was removed.
i can only assume that the boost gauge will show a quicker response or a higher ultimate boost level. but i don't know what effect will occur. if you still had a boost contorl fitted , it will already be effecting the spool up and the boost pressure achieved, so you probably would not see any difference if there was one.

i can't really think of any other way you could test the effect of removing a potential restiction removal.

[HPRULZ]

http://www.autospeed.com/cms/article...tions&A=110824
interesting article on fitting ram air induction to a VR4 may have some use to you.

Kev

[fassi1]

I guess you don't want to be getting negative pressure (vacuum) just before the exit of the snorkel.
Great article Kev.

[Tam]

Hi Dave,

Very cool thread and questions posed. Could you not try a "by the bum dyno" and just remove your bonnet and see how that feels? Also seen on some bikes with home made ram air by removing a headlight and running the channel forward into the high pressure air before its disturbed by the fairing. With bikes they say that ram air only really starts working above 100mph and the airbox design needs to be of a sufficient size to have enough static air for the engine to draw in. With turbo'd cars i dont know how vital this static air is.... I just remember from when i used to watch the DTM cars when the bonnet was removed from the car all you could see was an airbox.

Marc

[fassi1]

I bought a vacuum gauge, should be with me very soon.
Will try to monitore the pressure somwhere around the outlet of the snorkel and somwhere else
and see if it comes up with something clever.

What I'm thinking to do is cut in the snorkel with min 50mm pipe like demonstrated on the picture and run pipe to the bottom of the bumper fitting its inlet somewhere in high pressure area. 50mm diameter pipe is roughly the difference between inlet and outlet of the snorkel.
Yellow cross would be the location for pressure test. Test can be performed with extra inlet blanked and opened. If there is restriction at the very inlet of the stock snorkel, the test should give positive result.

[HPRULZ]

I bought a vacuum gauge, should be with me very soon.
Will try to monitore the pressure somwhere around the outlet of the snorkel and somwhere else
and see if it comes up with something clever.

What I'm thinking to do is cut in the snorkel with min 50mm pipe like demonstrated on the picture and run pipe to the bottom of the bumper fitting its inlet somewhere in high pressure area. 50mm diameter pipe is roughly the difference between inlet and outlet of the snorkel.
Yellow cross would be the location for pressure test. Test can be performed with extra inlet blanked and opened. If there is restriction at the very inlet of the stock snorkel, the test should give positive result.

If you have a look at some of the other threads on the site I posted there are a lot of pieces of cool information regarding pressure zones and airflow but I liked the main article as it detailed the high and low pressure zones for a VR4. I shall follow this thread and see how u get on.

Kev

[fassi1]

It's all very exciting. I've ordered all the bits for additional air ducting, went for slightly bigger diameter 60mm.
Hope this test will give something positive.

[Davezj]

remember also that there are extra holes in the air box for water drainage and for the screw behind the battery. so you might want to removethe air box and block the holes up in there.
te article linked above by kev specifies not to take te air from under the car as this is a source of low pressure, so i know it is more work but you do need to get the extra intake pipe to the front of the car somewhere. to make any difference.

[fassi1]

Thanks for the tips Dave. I didn't mean the right bottom cause liku you said thats negative pressure area.
Will try to fit trumpet right next to the intercooler or where the fog light seats as I don't have em.

[elnevio]

Just be careful of puddles and standing water with low-lying air intakes - water doesn't compress very well!

[swinks]

Just be careful of puddles and standing water with low-lying air intakes - water doesn't compress very well!

But it's costless water injection setup, powah gains are endless!

[Davezj]

next on my list tomasz, i have a resovoir and a pump, i just need a injector nozzle/mister.

i am programming my own Arduino based controler as well.

[fassi1]

But it's costless water injection setup, powah gains are endless!

Yep that's what I'm expecting, huge power gains
Not sure if internals will take it.