Simply put I am trying to decide if I really need a bigger intercooler. My concern is not cooling as it seems to do a pretty decent job but flow. I have a T70 turbo and am running 15psi through a 24x11x3 ebay intercooler core. The IAT wide open runs at about 100-115 degrees on a 80 degree night. It just seems with the size of the turbo and the capacity of the intercooler it may significantly hold back volume of air flowing into the engine.

Any input or experiences with flow issues not so much cooling issues? Obviously more area is going to flow better but I would like to see some evidence/experience of how sizing effects flows in the large turbo rotary world.

I am getting to the point where I am going to throw it on a dyno in the next few weeks and I want to be sure the car is running 100%.

 

It sounds to me like your problem is an overly-large turbo as opposed to a small intercooler. However, I guess it is possible that your cheapie Chinese intercooler has some type of internal flow restriction that is not visible from the outside.

Intercooler flow restrictions are indicated by pressure drop. In order to measure the pressure drop, install an additional boost gauge just prior to the intercooler inlet. Compare this gauge with your current manifold pressure (boost) gauge. Generally, a restriction is defined as a difference of more than about 1.5psi at 10psi boost (or roughly 1.75psi at 15psi boost). The dimensions of your current intercooler should flow more than enough for your engine, so a better brand of the same dimensions should work well as a replacement if your current intercooler is too restrictive. Also, rectangular intercoolers will have a higher flow rate if the end tanks are mounted to the long edges as opposed to the short edges.

 

Tell me about it, I went with this turbo as a learn/curiosity experience and I will probably never go that big again.

Ill try that boost guage idea later this week and see how it turns out.

 

its interesting! it'll also tell you how good/bad the intake piping is

 

I'm running the same size intercooler from ebay. Flow seems fine with my t70 and 2.5" piping. I'm pushing 23 psi through it. As long as the flow area of the intercooler is large enough to flow the air before it's speed becomes too fast and turbulent it won't have a huge effect on flow. The amount of turns and the pipe sizing, bov location and pipe length also play a roles in flow. A too large core will have a higher pressure drop and also reduce boost response. Something to consider with a large turbo like that.

 

Dude what intake temps do you get with your setup?

 

Mine are always below 50c but i have 500cc of preturbo water and a cold air intake for my turbo

 

I have not actually tested my intercooler but I tuned on 20psi with 110 and the car seemed to pick up about 10whp over 15psi. Also the car is not very fast at all and it is a T70 turbo with a 1.10 Turbine A/R and it does not feel much faster between when I run it on 10 psi or 20 psi. I am thinking intercooler flow issues.

One thing as well is I have never seen an intercooler get so cold, even on a warm day after some WOT passes the intercooler becomes cold. Would this be a sign of restriction?

 

The same formulas for figuring turbo size can be used to figure out what intercooler piping diameter you would need to sustain the kind of velocity and flow for the system optimization.

www.turbobygarrett.com
Hit the system optimization link. Very interesting tool and its out in the open for everyone!
You just have to be able to calculate for rotary flow @boost pressure. Easy if you look at the link at the top of this forum.

 

You should feel a huge difference between 10 and 20 psi, thats like 150 hp. what size piping do you have? Intake temps? Straight piping or lots of bends? Sounds more like a boost leak to me. Pressurize your system and check for leaks. I saw one guy forget to tighten the bolts around the turbo compressor and it was leaking at the turbo which cost him a lot of power.

 

yea thats what I am thinking about the power difference. The piping OD is 2.5 inches, no its not huge but that shouldn't hold the flow back that drastically. The bends are pretty good, there are a few 90 degree bends but nothing more.

I do not think I have a boost leak I have already checked into all the couplers and piping and it holds pressure to redline. However testing it will only tell 100 percent.

Really it feels to have about 320whp on 20 psi witha T70 turbo, something is not adding up.

 

I'm running 2.5" piping and a medium size ebay core. I don't think it's your piping or the intercooler. It really sounds like your turbo is running out of efficiency. Unless you're running a cat thats clogged or have some kind of major exhaust pressure holding it back. A boost leak could be anywhere. The turbo, couplers, bov, gasket, injector o-rings, etc. You can test how much pressure loss you have at the intercooler by measuring boost pressure with your gauge before and after the intercooler and subtracting the difference.

 

I sure hope a T70 is not running out of efficiency. I am running nearly the exact same setup as above minus the fact that I do not have water injection and a smaller intercooler

Oh BTW!!! I just noticed that I had put the wrong intercooler size in the original post. MY intercooler is 18x6x3. Lot smaller then I originally posted.

according to http://www.turbobygarrett.com/turbob...tercoolers.htm that is equal to a 300hp application.

 

Well if it's got a big leak and making 40 lbs of boost just to get 20 into the engine then it would be running out of efficiency. Usually air temps would be quite high though. Something is definitely wrong since a t70 should come alive at 20 psi, It seems unlikely it would be the intercooler.

I think we are running the same intercooler. Mine looks something like this, not sure on the exact dimensions.
EDIT: saw your edit, yeah yours is smaller then mine. Just hook your boost gauge up before the intercooler and see how much more boost it reads. Then you will know the pressure drop.

 

an intake pressure tester will go a long way to see if you have any major boost leaks too.

 

just went out with a boost gauge before the intercooler and at the intake manifold. it is exactly 10 psi through the powerband at mani. Yet it would climb to 13-14 psi before intercooler 6k rpm on. I would say that is the restriction. Opinions?

 

I've heard 1 to 2 psi drop is typical through the intercooler. But i think thats just for the intercooler. I would think the manifold also has a certain drop, as well as the piping. Either way you should still feel a big difference between 10 and 20 psi. Check the pressure drop at 20 psi if you're tuned for it.

 

I put the new intercooler on and the car seems to be making more power and that pressure loss went away. Now the next problem is trying to solve the lag, turbo spools just fine rolling on to it but whenever I shift it completely falls on its face and has to build boost again. I seem to think it is my 3 inch DP into racing beat NA exhaust. My thought is on shifts all that back pressure is slowing the turbine wheel down. Ideas?

 

what do you mean when you shift? like WOT driving or just driving around with a moderate amount of throttle?

 

WOT, I have never seen a turbo drop off boost between shifts like this one does, it is quite dumb . I wouldn't say it is lag related because it will hit 10psi in 1st gear.