Offroad-Express

Hi all
Recently i finished turboing my gq with a tdo5h from a wrx
Man does the thing haul compared to when it had a ct26.
Is currently running about 10psi and am wanting to up it to 15psi but have learnt that it should really be intercooled first.

My question is ,What size would be considered to small? As in the area of the cooling fins?

This would be for a top mount as want to keep the length between turbo and manifold as short as poss to keep lag at a minimum.
Thanks
Mike

forgot to add am wanting to use an air to air

Honestly I have done a few comparisons and intake length does not effect the 'lag' as much as one would expect and using a front mount would benefit from not having any issues with heat soak.
But if your certain you want to go the top mount route i would recommend using a water to air setup.

My 5c

Completely agree with Will, as for intercoolers, seeing as your using a WRX turbo running about the same boost and assuming its sized coerrectly you could just try a WRX intercooler or something of similar size.

Now feeling like a right plonker.went and fitted a small top mount (190mmx240mm fin size) before asking question. Oh well. lesson learnt!!
Is a subaru water to air big enough or do i need to look at something else.

you can go too small... but you can't really go too big as already said, the increase in lag from intake volume is slight.

W2A setups are cool (get it )- but are complex and heavy.

top mounted with a fan drawing down through the IC is fine as is a front mounted IC.

And yeah they go like stink with a turbo added! Went for a ride in a DSR equipped SWB truck last week and It was amazing for just 10psi. Cant wait till he cranks it to 15 and takes me for a ride!

Lots of cheap IC's on trademe but i would stay away from the older cores which are covered in oxide and covered in bent fins. New ones aren't that much more expensive.

are you going to be using it in the mud
if so a front mount would get covered in mud and loose it's efficiency
i was also under the impression water to air is better with 4wd as they work better at low speed because air need airflow to work affectively

mercutio wrote:are you going to be using it in the mud
if so a front mount would get covered in mud and loose it's efficiency
i was also under the impression water to air is better with 4wd as they work better at low speed because air need airflow to work affectively

If u chuck a fan under it drawing air through it should be good enough at low speeds.

Im going to be using a subaru W2A setup on my 3 litre with a DSR430 and about 18psi.

Yep. most of the runs we have down here(southland) do involve mud hence wanting a top mount.
For those in the know would a fan underneath work as well as a water to air?
As have already have hole in bonnet would prefer to stay air to air. Just wondering what a good size would be.

to make the top mount air-air work properly you will need to insulate it from the rising heat soak. A fan will help but it will need to run continuously.

To make a top mount work on a GQ you need to do a few things. Ideally you'd want one at less 300mm x 450mm x 100mm. (but bigger is better)
Then make a shroud and fit a big fan. You need a scoop on the bonnet and if it is in the back 1/3 of the bonnet then you may as well face it to the windscreen as that is the high pressure zone. (the actual hole I'm talking about here)

If you really want to cool your under bonnet temps in GQ then you need to fit 2 vents in the bonnet just behind the headlights. These will suck the hot air from the radiator out and then it will flow off the bonnet and not into the I/C intake. They also reduce under bonnet pressure so allow more air through the bonnet scoop. (look at Aaron Smythe's bonnet aka MUDYAZ racing)

If you do this then the fan will only be needed for low speed as the airflow at road speeds will take care of itself.

Subbie w2a is OK for standardish TD42 but if you're going to run 15psi then it will struggle and there are better ways that aren't very dear.

Cheers for that. So i get this right your sayin that if i have cooler at rear of bonnent i should face the scoop towards the windscreen as it would get better air flow?
Was going to vent the bonnet along the side of the rise in bonnet. This work or to small an area?
Which of these would be better?

http://www.trademe.co.nz/Browse/Listing ... =362542543
or
http://www.trademe.co.nz/Browse/Listing ... =364011230

The GTI-R's have a fairly decent sized core compared to the subaru.

crazyclark31 wrote:Cheers for that. So i get this right your sayin that if i have cooler at rear of bonnent i should face the scoop towards the windscreen as it would get better air flow?
Was going to vent the bonnet along the side of the rise in bonnet. This work or to small an area?
Which of these would be better?

http://www.trademe.co.nz/Browse/Listing ... =362542543
or
http://www.trademe.co.nz/Browse/Listing ... =364011230

Yeah I know that sounds strange but the air pressure builds up at the windscreen. When guys lift the back of the bonnet they end up with fumes from the engine bay coming out a low speed and then fresh going into the engine bay at higher speed.
If you want to test it then tape a piece of plastic over the hole in the bonnet and go for a drive. If it lifts up then air is coming out where as if it goes down then air is trying to get in the engine bay. Obviously different things will happen at different speeds. Stationary it is likely the fan will push enough for air to come out the hole.
I use to have the bonnet spaced up on my GQ and at low speed you got engine smell in the cab via the vents but at speed (and not that much) there was now at all.

I know what your saying about vent the side of the bonnet ridge and it is something I've thought about but haven't tried. best you tell me the results!! But it sounds like a good plan if you do it right near the front. There is an area of low pressure at the front of the bonnet that you want to use for this.

I ran a GTiR on mine and that would be the absolute minimum size I'd recomend. Bigger would be better though. The good thing about the iR is it is quite heavy ali so easy to work with and is a welded core. (not glued)

darinz wrote:

crazyclark31 wrote:Cheers for that. So i get this right your sayin that if i have cooler at rear of bonnent i should face the scoop towards the windscreen as it would get better air flow?
Was going to vent the bonnet along the side of the rise in bonnet. This work or to small an area?
Which of these would be better?

http://www.trademe.co.nz/Browse/Listing ... =362542543
or
http://www.trademe.co.nz/Browse/Listing ... =364011230

Yeah I know that sounds strange but the air pressure builds up at the windscreen. When guys lift the back of the bonnet they end up with fumes from the engine bay coming out a low speed and then fresh going into the engine bay at higher speed.
If you want to test it then tape a piece of plastic over the hole in the bonnet and go for a drive. If it lifts up then air is coming out where as if it goes down then air is trying to get in the engine bay. Obviously different things will happen at different speeds. Stationary it is likely the fan will push enough for air to come out the hole.
I use to have the bonnet spaced up on my GQ and at low speed you got engine smell in the cab via the vents but at speed (and not that much) there was now at all.

I know what your saying about vent the side of the bonnet ridge and it is something I've thought about but haven't tried. best you tell me the results!! But it sounds like a good plan if you do it right near the front. There is an area of low pressure at the front of the bonnet that you want to use for this.

I ran a GTiR on mine and that would be the absolute minimum size I'd recomend. Bigger would be better though. The good thing about the iR is it is quite heavy ali so easy to work with and is a welded core. (not glued)

That answers alot thanks
Will go with the gtir core then and the vents down the side of hump.Will post some pics(if i can figure out how!)and results when it done.
Sorry to sound sceptical but will give the backwards i/c scoop and see how it goes. .

Well you'd a complete muppett if you believed everything people told you on the internet! I question absolutely everything as that is how you learn. I find if you question someone and they get pissed off then it is normally because they don't actually know what they are talking about and are just repeating what they have heard without understanding how it works. And that equals dangerous advice!!!!!!!

have to agree with you on that one. Am learning to sort the wheat from the chaff when comes to stuff of the internet. In saying that have found most advice from the "old hands" on here to be invaluble.
Have put some tape on back off bonnet and guess what. It did as you say and was sucked down the back of bonnet! So will be going with the reverse mount for some proper testing.