Jump to content
HybridZ

Dual intercooler efficiency question


Guest DaneL24

Recommended Posts

Guest DaneL24

Okay, I'm planning on putting an L28ET (stock T3) into my '71 240Z this summer. I want an intercooler, but would rather choose a junkyard unit than spend big bucks for an aftermarket intercooler. I know that OEM intercoolers are usually less efficient and more restrictive than aftermarket intercoolers, just so you know that I'm aware of the tradeoff with price.

 

But my idea was to use two OEM intercoolers (not sure from what car yet). Since there will be twice the cooling medium, cooling should be more efficient. If I plumb the intercooler piping to fork to both intercoolers after the turbo (instead of air going into one intercooler than the other...flow splits in half to two different intercoolers.) it should increase the total flow (two intercoolers have twice the flow capacity of one intercooler) and there will be less of a pressure drop. I think the price of two junkyard OEM intercoolers should be low enough and efficiency enough that its a better option than an expensive aftermarket intercooler.

 

So what do you guys think of this idea. Will it allow better cooling and less of a pressure drop like I think it will. I'm pretty sure the cooling effect will be better, but I'm not quite as sure about the pressure drop. Is the pressure drop after the intercooler due to the intercooler acting as a flow restriction, or the extra volume of the intercooler. If the flow restriction causes the pressure drop, this idea should work. If extra volume causes the pressure drop, then I'll go back to the drawing board...

 

Thanks in advance.

Link to comment
Share on other sites

Pressure drop is caused by restriction. You will cut your pressure drop by 75% with paralleling intercoolers. Most folks make the mistake of plumbing them in series which will double your pressure drop (cooler air, but stupid). It's a good idea; what intercoolers were you thinking of using? The Ford Probe/Mazda 626 ICs might be good candidates, or possibly Audi or Saab 900 intercoolers.

Link to comment
Share on other sites

Guest DaneL24

Parallel vs In Series Intercooler Plumbing...thats the word I was looking for, and yes thats what I mean. I thought that flow restriction caused pressure drop, so I figured two parallel intercoolers would be better than one because they increase the flow. I have easy access to Volvo, Audi, and Saab intercoolers at a local yard. I could probably find a Mazda 626 at the same yard. I would also keep my eye out for Buick Grand Nationals and Mitsubishi Starions. It would cost me about $75 for an intercooler at that yard...so $150 total in intercoolers. Whatever intercoolers I get, I would just make sure its two of the same intercooler, so flow isn't uneven between the two. Not exactly sure which intercooler to go with yet, I just know which are available to me at local yards.

Link to comment
Share on other sites

so $150 total in intercoolers.

That is just one small part of the total cost. Figure out how you are going to plumb it, then factor in the cost of all that mandrel piping, "Y" connections into the I/Cs and into the TB and all the connector ho$e$. Remember that the "Ys" must have the right spacing to properly line up with the parallel I/C pipes so chances are someone will have to make them. Only then will you understand the true cost for a solution that MIGHT get you what you want. Do not fall into the trap of thinking a solution is cheap because you can get parts from a junkyard.

 

Ironically I have not heard any mention of how much HP you plan on making and that is the determining factor in the flow capacity of the I/C you need. I bet you will find that there will be little cost difference in the end with going for a single I/C from RRE or being patient and ready to pounce on a good deal for a quality I/C when it becomes available.

Link to comment
Share on other sites

Scottie is right about the mandrel sections. I had to pick up two tight radius mandrels for my set-up, and they were 35 bucks each. :shock:

 

Not to mention the one u bend I ruined by having the muffler shop try to expand it and it split, and the other one that was not quite right that I had to scrap. Yes I did my own work which saved me some money, but still.

 

also you have to make sure your welds don't leak, if you use flux wire like I did.

 

I think I had about 300 bucks in all my mandrel sections by the time I was done. Yes I have some left over, and that includes what I used for the downpipe and plumbing my MAF for the JWT set-up.

 

Also consider the flow you lose. Each mandrel 90 bend will knock off 3% roughly, and I only have 5 bends in my entire intercooler plumbing.

 

Cheap initially doesn't mean cheap by the time its done.

Link to comment
Share on other sites

Guest DaneL24

I meant $150 for the intercoolers themselves...I already know that doesn't include the price for plumbing. I was actually thinking about using PVC pipe for the intercooler plumbing. It works pretty good for a "spud gun" with internal combustion, so why not for intercooler plumbing with boost PSI? I was also thinking of using wide sections of radiator hose for the some of the bends in the plumbing, as well as PVC pipe bends of course...it really depends what works best when I actually start plumbing all the pipes together. It should be able to hold up under pressure...so why not have radiator hose as an option too?

Link to comment
Share on other sites

I meant $150 for the intercoolers themselves...I already know that doesn't include the price for plumbing. I was actually thinking about using PVC pipe for the intercooler plumbing. It works pretty good for a "spud gun" with internal combustion, so why not for intercooler plumbing with boost PSI? I was also thinking of using wide sections of radiator hose for the some of the bends in the plumbing, as well as PVC pipe bends of course...it really depends what works best when I actually start plumbing all the pipes together. It should be able to hold up under pressure...so why not have radiator hose as an option too?

 

PVC will not last long. It is not rated for any kind of temperature - it will flow and burst very quickly.

Link to comment
Share on other sites

You don't want radiator hose. You want as much hard pipe as possible. Any hose has the potential to expand, which is spool up time, not to mention radiator hose pops off easily. I have about 1 foot of hose total in my set-up. I also used several of those silicon turbonetics hump connections, and I used nitrile hose (1/8th to 1/4 inch thick not sure) which is very rigid for the other connections.

 

Get good clamps too. I reccommend the one's Road Race Engineering sells, and I got my nitrile hose from them too. The heavy duty worm gear clamps they sell work very well.

 

PVC sucks, and they have restrictions in the elbows.

Link to comment
Share on other sites

Pressure drop is caused by restriction. You will cut your pressure drop by 75% with paralleling intercoolers.

 

Wouldn't you be cutting the pressure drop in half with two intercoolers in parallel? Have I missed something here?

Link to comment
Share on other sites

Pressure drop is caused by restriction. You will cut your pressure drop by 75% with paralleling intercoolers.

 

Wouldn't you be cutting the pressure drop in half with two intercoolers in parallel? Have I missed something here?

 

James stated the calculation above - pressure drop is proportional to the square of the flow, the same principle that allows injectors to increase flow only with the square root of the fuel pressure.

 

Doubling the flow (two intercoolers) will drop the restriction by a factor of 4, or 2 squared.

Link to comment
Share on other sites

Guest Anonymous

I'd steer away from the two parallel intercooler idea. Someone mentioned before you're going to need several y connectors, more piping (just lost your pressure drop advantage), and a complex system of pipes. The twin turbo supra has a descent size SMIC that you could probably mount as a FMIC. I'd stay away from the starion's. I've heard they're not very good into double digit boost. Depending on how close your project is to completion I'd wait on the intercooler and pipes and scan parts sites to find a descent FMIC someone is getting rid of. I'd tell you some sites but then I'd be giving away some of my secrets!! :wink: As far as the plumbing goes I'd try to do the most direct way possible. There goes parallel and all of its y connectors out the window. If you do a parallel and if the tubing would be anything like I'm imagining it would give you some serious lag and negate what pressure drop you saved your self from. Along with the direct route method I'd buy descent quality hard pipes unless you like replacing your PVC pipes or reconnecting radiator hoses. Doing it right once will save you alot of headaches later.

Link to comment
Share on other sites

Speaking of intercooler plumbing- I am buying it all right now for my 240ZT w/ NPR, and it's not fun! It will cost around $150 just for the silicon connectors and clamps. Those transition connector$ - ouch. Then about $100 for the mandrel bends in aluminized steel. The NPR cost me less than actually hooking it up!

 

Sean73

240ZT in progress

L28ET, T3/T04E, NPR, Z31 ECCS

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...