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Liquid to Air VS Air to Air intercoolers (discussion)

 
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Thu Sep 28, 2017 1:54 am    Post subject: Liquid to Air VS Air to Air intercoolers (discussion) Reply with quote

In my track car project, im planning for a power output of 600hp. Still undecided if im going the 2L or a 2.5 - 3L 944 block. (i have a few options on the table) so im basing everything i do around the 600hp mark. Even if i get 500hp which is more reasonable, there's always headroom.

track car is more of a street based time attack car. So it will get driven on the street for fun, and do track days for fun (usually 20-30 min sessions) and time attack sessions which is big here in Australia (1 fast lap, so you can cruise for 3 laps or so to cool the car down and go for another lap ect.

***front bumper has to be stock, i can put a 944 valance on, but rather keep the 924 look***

The big issue is room for a big front mount intercooler like a 3" thick core. mounting that in front of a radiator that will most likely be a 2.5" core that'll also be cooling a liquid/oil cooler.
This means moving the radiator back closer to the engine to fit the intercooler. this isn't a huge deal with the 2L pending turbo placement, but can be an issue with a 944 block as it's longer/closer to the front.
So the idea of a liquid to air cooler came into play.
PWR make a barrel style cooler so i can ideally place that under the nose panel.
But i still have to place a heat exchanger. I can put that in front of the radiator so it'll get moved back a little, and because it's thinner, airflow to the radiator wont be affected as much. Or i can remotely place it at the back of the car with a set of fans.

But i have no real world data with Liquid to air intercoolers as it's not to common as it's more expensive and more complex.

Can anyone see any pros and cons with either setup?
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ideola  



Joined: 01 Oct 2004
Posts: 15499
Location: Woodstock IL

PostPosted: Thu Sep 28, 2017 2:31 am    Post subject: Reply with quote

The big question is how long do you think you'll be on boost at any given time. Liquid to Air is more ideal for successive short bursts of boost, while Air to Air is more ideal for long boost runs where the car is in continuous acceleration or sustained motion (i.e., not successive decel / accel events).

Based on what you describe, I would design the system to be optimized for the time attack use, and good enough for the street. Consequently, I would lean pretty heavily toward a larger, highly efficient air-to-air unit. I don't think the added complexity of a liquid to air system makes sense for your application, and it would be less than ideal when you want the optimum cooling capacity during time attack events.

  • To achieve 600 BHP you need at least 900CFM air flow capacity in the intercooler (rule of thumb is BHP x 1.5 = CFM requirement).
  • Minimize bends and length of tubing runs to minimize pressure loss.
  • Pay particular attention to the end tanks to optimize the flow of pressurized air into and out of the intercooler.
  • To optimize efficiency of the intercooler itself, consider a fan to pull air through it.
  • Avoid stacking heat exchangers. You could put a massive IC in the current radiator location, and then go with a split radiator set up for engine cooling, one for the block and one for the head, one on each side of the car behind the headlights (which is what the GTRs eventually moved to). This configuration would probably require a fixed headlight conversion. If you have to stack, get the spacing right between the heat exchangers to minimize turbulence, and seal the entire perimeter of the gap.
  • Fabricate proper duct work to optimize flow of ambient air across the IC. This means a duct with a frontal opening that is roughly 60% the size of the frontal area of the IC, with the sides of the ducts sealed all around the perimeter of the IC frontal area.
  • Add a ducted extraction vent in the hood behind the IC
  • Do the proper planning and calculations to size the IC and charge tubes relative to the turbo (refer to Corky Bell's Maximum Boost book)
  • Model your intake after the GTR/GTP setup (i.e., ditch the factory intake, and get the throttle body out front). This orientation will help minimize length and bends of charge tubes to and from the IC.
  • If rules permit, add IC sprayers that mist the IC fins with vaporized water during boost runs.
  • If rules permit, add a Stage 2 water-meth injection kit to provide additional boost cooling and octane rating (note that my intercoolers come preconfigured with a port for water meth injector!). The stage 2 setups have a microcontroller (that could be tied in to your EMS) that spray progressively more solution as boost increases. Thresholds and ceilings can be set so that you can optimize the boost cooling effects where it is most needed based on the adiabatic efficiency of your turbocharger.


600BHP is pretty ambitious, especially for a 2.0L. The best the factory ever got with the 2.0L lump is ~450BHP according to Roy Smith's book, albeit that was without the benefit of modern engine management.
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15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Thu Sep 28, 2017 3:25 am    Post subject: Reply with quote

Brilliant info dan, Thanks!

Although i did forget to mention, the radiator must retain in the factory location. So i can move it a little for going larger radiator ect but has to be in that spot, roughly.

but i think you've got a good point going with a front mount. But i have no choice other than going stacked. If i go stacked, i'll have both cores the same size and maximise ducting so air does not flow around the units.

Bonnet ducting will be there.

Headlights are fixed which helps with space.

I like how the gtp intake is made. I think i can replicate that, even with the IC in front of the radiator. Might need some cutting under the nose panel, but that's no issue.

Sprayers are on the table. ECU controlled, no problem.
Meth injection is not. Im pretty sure it is allowed, but not something i personally like.
Engine will be e85 fed 100% of the time.

I'll have to do some measurements. i'll have a look tomorrow.

Look i think 500hp is possible from the 2L with the right mods. 600hp at the flywheel is a big task but again, im not doubting it. If i do go ahead with the 2L build, i'll be doing everything possible to squeeze power from it. I'd still be happy with 450hp. though. Just aiming high. the 924 block should take 30psi. But it's not like i plan to run 30psi all day every day.

500hp (wheels) is not so difficult with a 944 block. Mine in my 944t is a 500hp capable block. if i turn it up to 25psi it should hit 500whp. But i dont plan to.
I do have a closed deck block on the table if i want to go that route, that is 550hp capable.

Look at it this way, 3 years ago if you said 700hp 968 engine, everyone would say it cannot be done. They're actually calling it 800hp from the amount of air and fuel going into the motor. If you had said 1000 - 1200hp 968 engine, Just wait a few weeks. Theres a billet one coming from Europe. Ok It's billet and 4L but still, we're moving forward with it.

I believe the same can be done with the 2L. Extensive head work, and a solid bottom end. Ive just been doing my homework and i have planned out a high hp 924 block.
At the back of my head, i want to go with the 924 block just to keep it all 924.
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ideola  



Joined: 01 Oct 2004
Posts: 15499
Location: Woodstock IL

PostPosted: Thu Sep 28, 2017 3:35 am    Post subject: Reply with quote

Paulyy wrote:
Meth injection is not. Im pretty sure it is allowed, but not something i personally like.


Why? It's a beautiful thing. I have it on one of my cars. It's cheap, easy, simple, and very effective. It adds a wonderful margin for error. There's even a post somewhere here on the board with an engineering article published by Porsche that discusses the tremendous merits of this approach. I wouldn't be so hasty to rule it out.
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Thu Sep 28, 2017 3:47 am    Post subject: Reply with quote

ideola wrote:
Paulyy wrote:
Meth injection is not. Im pretty sure it is allowed, but not something i personally like.


Why? It's a beautiful thing. I have it on one of my cars. It's cheap, easy, simple, and very effective. It adds a wonderful margin for error. There's even a post somewhere here on the board with an engineering article published by Porsche that discusses the tremendous merits of this approach. I wouldn't be so hasty to rule it out.


I dont think there's anything wrong with it. I know the potential using it. I just dont like the fact if something stops working, i.e electrical issue, injector stops, ran out of meth ect, i cannot run the engine at it's maximum. I know it's a low probability.

But allowed to run e85 gives me the headroom.

But at the end of the day, if it comes to running meth injection, i'll end up doing it. but i rather not.
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ideola  



Joined: 01 Oct 2004
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PostPosted: Thu Sep 28, 2017 3:56 am    Post subject: Reply with quote

Makes sense. I like the E85 option.

Which EMS are you planning to use?
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Thu Sep 28, 2017 4:10 am    Post subject: Reply with quote

ideola wrote:
Makes sense. I like the E85 option.

Which EMS are you planning to use?


I have a Motec m400 with a few nice features unlocked. I've got launch control, flatfoot shifting, antilag, traction control and a few others unlocked.

e85 is widely available here. I can buy e85 in barrels but it has MTBE in it that not all injectors like.

The m400 does allow me to use twin injectors per cylinder in a sequential setup if i do choose to run MTBE safe injectors.
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Cédric  



Joined: 27 Aug 2004
Posts: 1718
Location: Sweden

PostPosted: Thu Sep 28, 2017 6:50 am    Post subject: Reply with quote

You should have a chat with joakim.s, he have some serious power and a pretty clean install. If you missed it here is a quick vid from the dyno, you can see his IC aswell, fits pretty neatly in the car, the turbo and manifold on the other hand..

https://youtu.be/Maae0lF1mXs

Here is his car thread, http://www.944sverige.com/forum/viewtopic.php?f=17&t=19326&start=405

Will need a Google translate though
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Fri Oct 06, 2017 12:46 pm    Post subject: Reply with quote

Cédric wrote:
You should have a chat with joakim.s, he have some serious power and a pretty clean install. If you missed it here is a quick vid from the dyno, you can see his IC aswell, fits pretty neatly in the car, the turbo and manifold on the other hand..

https://youtu.be/Maae0lF1mXs

Here is his car thread, http://www.944sverige.com/forum/viewtopic.php?f=17&t=19326&start=405

Will need a Google translate though


Yeah i've been though his thread a few times, and seen that video a lot of times. Thats the only vid giving my good hope if big hp goals.
But there has been no update on his build?

I'd really like to see that car on the street or track with the latest setup.
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1549
Location: Not Detriot - NMI

PostPosted: Sat Oct 07, 2017 7:33 pm    Post subject: Reply with quote

I got a 3.5" core fmic infront of my rad by spacing it back some..
https://youtu.be/X2jbkENELMk

I had a thread but the pics are all dead.. intercooler or bust
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1551
Location: Somerset, UK

PostPosted: Sat Oct 07, 2017 8:05 pm    Post subject: Reply with quote

I’ll leave this here. I hope your ambition is as deep as your pockets.

http://www.speedhunters.com/2013/12/german-speed-metal-a-time-attacking-porsche-944-turbo/

Plenty more info on this car and engine build around the t’internet
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Then www.924board.org/viewtopic.php?t=31252
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Sat Oct 07, 2017 10:48 pm    Post subject: Reply with quote

Fasteddie313 wrote:
I got a 3.5" core fmic infront of my rad by spacing it back some..
https://youtu.be/X2jbkENELMk

I had a thread but the pics are all dead.. intercooler or bust


I am sick of how photobucket destroyed all photos. neat install.
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Sat Oct 07, 2017 10:50 pm    Post subject: Reply with quote

Carrera RSR wrote:
I’ll leave this here. I hope your ambition is as deep as your pockets.

http://www.speedhunters.com/2013/12/german-speed-metal-a-time-attacking-porsche-944-turbo/

Plenty more info on this car and engine build around the t’internet


Oh i know Patricks (the owner) car very well. I am actually going WTAC next weekend to watch the competition. Im building mine to run in the class lower than his "club sprint" He's in open class. And there's a 968 "RP968" in pro class. And that is on a whole another level.
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