Getting back to the FMIC project, I'm slightly worried about general cooling. The heat exchanger for the air-con lives in front of the rad and now of course, I'm planning on adding my FMIC in front of that, am I going to have any cooling issues, or am I worrying needlessly?

Does anyone think it would be worth adding a thicker rad and slimline fans, or would that be overkill?

 

ther is no such word
can you get slimline fans ?
are they off another model or are we talking aftermarket stuff like "kenlowe".

 

Think you are worrying. The fans will only actually be doing anything at speeds below 30mph. AFter that, there will be far more air flowing through the rads anyway.
Kenlowe are too expensive, and they arent that thin.
If you can find a supplier for them, Spal make good fans, and are anout the thinnest around. They come fitted to TVR's, and some other cars. I think that Pace supply them with their FMIC/Rad Kit.
Another thin one is Tripac, which are good, and available from Merlin Motorsport, and various other places. The Tripac are about the cheapest I think.
The 2 std Subaru fans will probably shift more air then any aftermarket fan though.

 

OK, next question: where should I put the DV? is it better closer to the turbo, or nearer the IC or does it matter?

Also, why does everyone charge over £1000 for FMIC kit when the core is about £150 and the pipework about £300? And thats at retail, robbing barstewards. At least the PACE kit includes a rad as well as an IC.

 

as near to the throttle body as you can get it.

Andy

 

I 2nd fuzz, as near to the TB as you can get...
Rob

 

Can someone explain why? I'm not doubting, but it doesn't fit with my understanding of what the DV does (or why we need one),

Cheers

 

page 3?????

top

 

Notorious,

In very basic laymans term (only way I know how to describe it)
the Turbo has a lot of pressure in it forcing the air into the inlet manifold. You take your foot off the loud pedal and the butterfly in the inlet closes. All that pressure is then all in the Turbo. So the dump valve dumps that pressure out.. either into the inlet past the butterfly (I think) recirculating DV, or to atmosphere. You can run without one but all the pressure remains in the turbo and the bearings don't like it. There would be less lag with out one and all the pressure would be there already when you openned the throttle after a gear change for example. Therefore you want the dump valve as near to the turbo as you can fit it so that there is less pressured air to dump...
and more importantly less area to pressurise, although I am doubting myself on this last bit as I type...

Anyone care to correct me if I am wrong?

I have just worked it all out as I go along.

JGM

 

Wonder if david managed to fit the fuel pump with one hand before he went away. No doubt find out when he returns.

BTW David when you return, i have ordered the FMIC and tubro so cant wait.

 

This is what I thought, but I was given advice to mount near the throttle body, which is about as far as you can get from the turbo, or am I confused as to where the TB is?

 

Thinking out loud...

The amount of air that is shot through the engine when you recirculate the dumped air would be catered for by the ECU..
If you run a difference ECU or a dump to Atmos DV I cannot see it making any difference whether it is nearer the turbo or the inlet..
surely a good guide would be to mount it as near as the standard location as you can get it??

I'd just like to add that I know nothing from practice so could be totally wrong.. I often am...

JGM

 

I would say that given the flow direction of air just before you lift off is towards the throttle body, then logically it would want to be nearer the throttle body so as to maintain that flow or pressured air, without it going into the throttle body.

ie if it were nearer the turbo then some air would inevitably end up back in the turbo and cause it to stall?

Just my opinion and understanding.

 

This has gone past my knowledge and I am stalling now

...

JGM

 

having looked at most of the FMIC available, they seem to have the DV no more than 1 foot away from the throttle body, and not 1 foot away from the turbo.

Just my thoughts again.

 

If you run VTA dump valve, all the air that is dumped on overrun still goes through the MAF sensor. So the ECU thinks there is more air going into the engine, so fuels accordingly, this is why you get more pops and bangs with a VTA dump valve.

With a re-circ, the excess air is fed back into the turbo inlet, hence the name.

Paul

 

Pavlo,

Yes as you say that is clear... but this makes no odds when talking about whether to put it near the inlet or the turbo?
does it not?..



When the throttle butterfly closes the air that is pressurised between the turbo and the butterfly is dumped through the dump valve, be it to atmos or recirculated. I cannot see logically what difference it makes if the dump value is near the turbo or the butterfly? the pressure is still released from the same section of pipe.. near the inlet the pressure may be released from the butterfly quicker then the turbo.. but such a marginal amount.. I cannot see any advantage or disadvantage with either set up?? some explain why near the inlet would be better?
Perhaps it is better but I cannot see why? but I have not understood your stalling reference Steven?
I suppose the pressure would drop the turbo end first if the dump valve was nearer the turdo so when throttle reapplied the blades could stall... I think I understand but this is only a problems if you come off and back on the throttle... which does occur I guess in normal driving.. cannot see it effecting the inlet.. so yes agree I think nearer the inlet sounds better... in my very very humble opinion.. he ring someone that knows... like an engine builder?



JGM

 

Hold on a minute... the pipe is rather long if you are going through the FMIc etc.. so as you are saying P20SPD nearer the inlet would be better... I was thinking the pipe is fairly short but this is not the case... so the difference in pressure would make a fairly large difference...

I am trying to rmemeber my MR2 Turbo engine as the intercooler pipes are a bit longer than the Scooby as standard and I think from memory the dump valve is nearer the inlet.. than the turbo..

Hey ignore me I work in IT

Going back to the muppet forum now..

JGM

 

Me too, if I can't reboot it, I get confused

Maybe I should get a 360 bearing turbo and do away with the DV alltogether?

 

Not read all the thread lately ,having no dump valve causes a lot more lag, the air in the turbo has nowhere to go when the throttle butterfly is closed and stalls the impeller... thus when you reapply the throttle the turbo has to start to spin from standstill again..=LAG LAG LAG LAG
On the dump valve positioning front.. the reason for having the Dv close as poss to the throttle body is because that is where the most pressure is when you shut the butterfly..
Rob

 

and you may retain some form of "flow" of air thro intercooler further reducing lag. (if your gear change is quick)

/\ followed on from last post

 

TY mate forgot that bit..
Rob

 

Back to work on the car David.

Have a nice holiday M8.

Steven

 

Is he back already....**** that week went quick
oooh is that the time got a party to go to bye

 

BTTT

 

Always miss the corners

 

at least we have the pages back in the right order of things.
Hmm I'm sure we did till this one ran on to the next page.
Rollox.

[Edited by Fuzz - 8/25/2002 1:30:24 PM]

 

dump valves just protect turbo, that's it.

If you don't have one, what do you think happens to all that air that the turbo compressed while you changed gear? That's right it's all there waiting for you in the inlet manifold at about 3 million psi, put your foot down and it goes in your engine.

P

 

no its comes back out of the system and past the turbo the wrong way, slowing down the compressor and creating more lag.

Si

 

QUOTE :
Notorious,

In very basic laymans term (only way I know how to describe it)
the Turbo has a lot of pressure in it forcing the air into the inlet manifold. You take your foot off the loud pedal and the butterfly in the inlet closes. All that pressure is then all in the Turbo. So the dump valve dumps that pressure out.. either into the inlet past the butterfly (I think) recirculating DV, or to atmosphere. You can run without one but all the pressure remains in the turbo and the bearings don't like it. There would be less lag with out one and all the pressure would be there already when you openned the throttle after a gear change for example. Therefore you want the dump valve as near to the turbo as you can fit it so that there is less pressured air to dump...
and more importantly less area to pressurise, although I am doubting myself on this last bit as I type...

Anyone care to correct me if I am wrong?

I have just worked it all out as I go along.

JGM




This statement is actually incorrect in a couple of areas, first of all a Dump valve is there to get rid of the boost when the butterfly valve shuts if there is no dump valve the butterfly in the throttle body shuts and the pressure between the turbo and the throttle body builds up this has the effect of shock wave of air aitting the compressor wheel of the turbo , hence slowing it down and increasing lag when the next gear is selected. With a effective dump valve in place the excessive pressure which would normally build up and slow the turbo down is vented and the turbo can keep its speed up. Secondly the best place for the dump valve is as close to the throttle body as possible this is why on cars with front mounted intercoolers the valve is always situated on the throttle body side of the plumbing rather than the turbo side. also alot of the subarus fit their dump valve to the front face of the intercooler its self. Hope this helps.

[Edited by duczz - 8/26/2002 5:01:07 AM]