WhangareiKE70

Will this intercooler be sufficient?

Recommended Posts

Hi all, 

Have tried looking, but couldn't find the info I was looking for.

Looking at an intercooler for my RB25DET Datsun 720 project. 

Intercooler core size I am looking at (A2A) 500x180x65mm.

https://www.trademe.co.nz/Browse/Listing.aspx?id=1795400654

Engine is RB25DET, expected power somewhere around 300-350hp. Mostly on road driving, I am aware of the limitations of A2A in offroad environments. The main reason I am looking at this size is it will package neatly behind the grill with minimal/no clearancing, and  allow for very short piping (around 1m total). Inlet/outlet size is 2.5" (63mm) which I have found info on, and believe to be sufficient? If someone believes otherwise feel free to chime in.

It is early to be looking at this, but I am fabbing up the rad support so I have to make allowances for mounting the intercooler/oil cooler etc. 

It is hard to get good info on this subject as most cars running RB25DET engines have intercoolers sized for trucks that hang hectic low and scrape in the KFC drive through.

If anyone could help or point in the direction of where/who to ask, that would be really appreciated. 

Share this post


Link to post
Share on other sites

standard falcon turbo one is similar size and theyre around that hp rating so if its a decent intercooler should be fine?

 

  • Like 1

Share this post


Link to post
Share on other sites

Sizing wise it should be ok, if there was any chance of going thicker say 75mm or even better 100mm this would help by reducing pressure drop across the cooler..

 

If a longer piping solution allowed additional cross sectional area I would look at that, because the pressure drop will be the limiting factor well before the internal volume of the cooler piping will cause you any issues.

The 180x65 core may not have much more cross section than the 2.5 inch piping once you do the maths. (The 500 length will only affect cooling capacity not flow rate)

  • Like 1

Share this post


Link to post
Share on other sites
1 hour ago, mjrstar said:

Sizing wise it should be ok, if there was any chance of going thicker say 75mm or even better 100mm this would help by reducing pressure drop across the cooler..

 

If a longer piping solution allowed additional cross sectional area I would look at that, because the pressure drop will be the limiting factor well before the internal volume of the cooler piping will cause you any issues.

The 180x65 core may not have much more cross section than the 2.5 inch piping once you do the maths. (The 500 length will only affect cooling capacity not flow rate)

Intercooler core:

180x65= 11,700 mm2

Intercooler pipe:

pi x radius squared= 3.1415 x (32.5x32.5) = 3.1415 x 1056.25 = 3,316.6

So cross sectional area of intercooler core is about 3.5x the piping. 

I can do math, just not performance engines. Will that difference be enough?

Share this post


Link to post
Share on other sites

That assumes the core is 100% open, which it isn't (all the passages etc) so actual surfacr area for air flow will be much smaller?

 

Share this post


Link to post
Share on other sites
17 minutes ago, Beaver said:

That assumes the core is 100% open, which it isn't (all the passages etc) so actual surfacr area for air flow will be much smaller?

 

Yeah, true, didn't think about that. Makes sense.

Moral of the story is, I bought it, and it is now on its way to me. It will do for mock up, and once everything is running, I will soon discover if it is suitable or not. 

I hope it is because I don't want to cut the grill. 

I appreciate all the advice all the same. I will make sure to try and report back once the project runs. 

-Hayden  

  • Like 1

Share this post


Link to post
Share on other sites

Haha yeh that's the best approach, give it a crack and see how she goes. Kudos for not wanting to hack the front up!

  • Like 3

Share this post


Link to post
Share on other sites
16 hours ago, WhangareiKE70 said:

Intercooler core:

180x65= 11,700 mm2

Intercooler pipe:

pi x radius squared= 3.1415 x (32.5x32.5) = 3.1415 x 1056.25 = 3,316.6

So cross sectional area of intercooler core is about 3.5x the piping. 

I can do math, just not performance engines. Will that difference be enough?

You can halve the surface area straight off as 50 % of the bar area has the external cooling air passing through to the radiator. Then take a look inside at the amount of vane material which extends into the airflow, minus this off next. 

Then take off the bar (or tube) thickness (top, bottom, and side material each bar is made from) as this is another reduction of internal surface area.

 

@Beaveris right though it will work, (so would a straight piece of pipe though) it just may not be optimised. 

 

 

Just to clarify I'm not trying to be negative - just trying to educate from my own experience.

  • Like 2

Share this post


Link to post
Share on other sites
17 hours ago, mjrstar said:

Just to clarify I'm not trying to be negative - just trying to educate from my own experience.

I get that, that is why I put the post up, to be educated.

I suppose I knew it wasn’t going to be optimal, just wanted to know if it was going to be a resounding “no, this won’t work at all”, in which case I would have to reassess. 

There was enough of a “maybe” for me to give it a go.

On 10/10/2018 at 16:27, Beaver said:

Haha yeh that's the best approach, give it a crack and see how she goes. Kudos for not wanting to hack the front up!

I didn’t say I wasn’t hacking up the front, just not the grill... hahaha. 

But seriously, trying to find the balance between old school looks and 4wd practicalities (bullbar, winch, proper clearance etc) is difficult. I’m gonna try incorporate the factory bumper into the bullbar somehow. 

Share this post


Link to post
Share on other sites

Go water to air and stick the heat exchanging radiator in the tray so it doesn't get clagged up with muck when you do use it off road.

Share this post


Link to post
Share on other sites

If you find the Intercooler is a bit small with I take temps being a bit high still, you could always do a water/meth injection setup which will help. Or stick a slightly larger compressor wheel on the turbo haha. 

Share this post


Link to post
Share on other sites

I'd say its on the small side for 350whp. Try find something thicker or taller for more cross sectional flow area (ideally).

My 230x550x63 IC was a significant restriction at 280wkw/375whp (awd) with something like 4/5psi of pressure drop. It cooled the air effectively but the flow area was too restrictive.

Now I have a similar size but 100mm thick and it has no pressure drop, also the tune needed more fuel and less wastegate duty for the same boost.

 

Edit: Also look at ITL intercoolers, had them recommended by a few people and do the trick while not costing the earth (could get their 500x300x100 cut down to 500x180x100 or so).

Share this post


Link to post
Share on other sites

Intercooler 1Intercooler 2

In place. There really isn't any room to go thicker, it is hard up against the grill and the rad support framing, and I have already had to trim the grill a fair bit in behind.

If I have to I can go for a  taller intercooler and cut out the bottom of the grill, I will just have to come up with a way of hiding it. This is something I want to be hidden/subtle, unlike everything else on this build. :lol:  

EDIT: Also, fun fact, the engine is actually in the engine bay in the bottom photo, hahaha, shouldn't have any problems with air pockets in the cooling system at least? 

  • Like 3

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now