from what ive seen the 2 stock cores together cools really well. however, while it flows pretty well for stock it still flows well.....like stock. it wont flow like an aftermarket core. big expensive FMICs from greddy HKS or whoever are expensive for a reason. a lot of R&D has been done to make sure that they flow as good as possible. 2 stock top-mounts made into a front-mount will be cheap, but it wont flow that well.

 

I don't neccesarily agree with the part about not flowing well. The way the guy welded the 2 together in the picture is the bad way to do it. He did it in series. You should do them in parallel to get better flow with less pressure drop. That would flow twice the air. The stock cores flow pretty good to begin with but with twice the fin area to flow through it becomes really nice.

 

I have one using 2 cores, tubes run vertical, had top and bottom tanks made and welded on. Works excellent, more internal surface area available than the in series method.

 

exactly!

 

yes they do flow good for stock cores, but im saying that an aftermarket core will flow a whole helluva lot better. and its not how they are welded or piping or endtanks that makes them not flow as well as the aftermarket units. its the core itself. its worth it in my opinion to actually buy an aftermarket intercooler from a big company because they work a lot better. besides FMIC from greddy are getting to be cheap now a days. the big core is only 1000 or so and the "small" one(still pretty big) is like 800 or so. thats worth it to me considering it will always perform better than any stock cores welded together in any way and it comes with all the piping and everything. just my .02

 

I have 2 starion cores welded together in parallel that I guarantee don't flow less than the Greddy units. The thing is absolutley huge. I only have about $150 invested in the whole thing which makes $800-$1000 seem absurd. That is Haltech money. Maybe it doesn't cool as well I don't know but for the price it is unbeatable.

Not saying you are wrong. I fully understand where you are going. The Greddy unit is a fantastic unit and I'd personally take it over any Spearco unit anyday. I think the point behind welding 2 T-II cores together is price and there are NO aftermarket units that can even approach such a cheap price.

 

sounds like a good idea...from the picture it looks like a sizeable IC by some aftermarket comparisons...Greddy does make nice stuff but like anything else it varies by application. Custom work does demand more respect than shellin out some $$ for the aftermarket stuff, but only if it's done well I'm goin starion route when I turbocharge at first...

 

The Starion intercoolers have pretty much been proven to suck. Use a damn Volvo intercooler, or something, but don't use the Starion ones.

 

well the thing is size doesnt really matter when it comes to how well it flows. it the design of the cores internals. the core tubes and such. stock intercoolers are designed to runs stock boost. i believe the pressure drop on the stock S4 core is something like 2 or 3 psi? you weld two together you just doubled your pressure drop. thats all at stock boost levels. i dont know what the pressure drop is at say...12psi. it very well may be more. aftermarket companies spent alot of time and money designing their intercoolers to have as little pressure drop as possible at elevated boost levels. while any custom fab work does command respect, when it comes to cooling down the charge air on an engine like the rotary, ill take the best thing i can get. aftermarket units are the best, hands down. im not trying to tell you to not build your own intercooler, by all means go ahead. im just saying that if you think its going to be efficient as a better designed core, youre mistaken. a custom unit will work, but not as well as any of the aftermarket ones.

 

Yes but say for instance that your pressure drops is say 4 psi on two stock tii intercoolers then you are cooling twice the amount that the stock boost levels are allowing for meaning you can run roughly 1.5 times that of stock boost safely... meaning like on a S5 TII you can run 12-13 psi... which in my opinion isn't that bad for something that costs you all of about $200? isn't it? i think it does REALLY well for the fact that you are doubling what you cool by doubling the core except the fact that you are doubling what the stock unit has for defects.... however i cannot see how the cons outway the pros... i think this is the way to go!!! in my opinion..

Rotary God
tell me how you intend on doing this something like in this pic?

that is what i had in mind! would it be better than running them in seies and welding them together?

 

Flow wise, it would be better to weld them in parallel.. but it kinda depends on how much room you have (or are willing to make) upfront...

 

..cooling wise I think it's better to mount them in series ( I think... ) but that will increase the restriction and pressure drop... I guess... :S

 

how do you figure that the series would cool better? explain why you would think this?
because i would personally think that the parallel would allow for less restrictions more flow and equal cooling... right?
someone help me out on this theory!

 

bump ^

 

not positive, but in my head the way it works is that all of the air will be flowing past a larger surface area and greater mass (heat transfer and heat sink)... (each air molecule flows past 2(stock lengths) ... where as in parallel 1/2 the air will be flowing past stock surface area... (each air molecule flows past 1 stock length) The longer that an air molecule is in contact with the surface, the more heat can be exchanged...
Although the heat sink capabilities of both designs are virtually identical (weight), the period in which the air would be in contact with the heatsink is longer in the series design...

And obviously the parallel layout would prevent less restriction (pretend they are resistors in a circuit... )

But I do think that the series mounting would fit better in the front of an RX-7...

 

Ok well which would provide the most amount of potential HP For instance with a T04RR Turbo wich would be better to better produce further HP?

 

Uhmm... I can't say for sure... but:

-more flow + less cooling = less pressure drop (higher boost) and more fuel needed due to higher intake charge temp...

-more cooling + less flow = more pressure drop (lower boost) and less fuel needed due to lower intake charge temp...

It really depends on:
a) turbo flow at the boost
b) restriction of the intercooler at that flow
c) some lovely fluid dynamics equations that I can't find right now...

So I can't say for sure...
..I'd prolly just go with whatever fit easiest... but then I'm lazy...

 

does anybody else have any insights on this idea? which would be better in series or in prallel for HP gain?

 

Glad to see you trust my opinion so much! (j/k)

So does anyone else have insight/corrections?

 

Well I do but you semmed kind of uncertain and with your insight you made me dought my original conclusion now i am looking for a third fourth and so on! to see what other think!

 

im going for the 2 s4 welded together, the guy who does all my work recons it makes quite a good cooler dont know if hes welding them in series of parrallel ive seen it in action at the drags on a car over here it did a 12.9

 

Many people like to quote from Corky Bell's book Maximum Boost (I have it in front of me now!). He says that doing cores in parallel is the best way since there is less pressure drop and that series is not a good way to go. Also to run them parallel to each other top to bottom instead of one core behind the other. In the case of the one behind the first it is only performing 1/4 the cooling ability of the front mounted core.

However another really good book I have says that the pressure loss associated with series welding is more than offset by the lower temperatures that it produces and therefore recommends the series way.

Kind of confusing so its hard to tell. I personally have my 2 Starion cores welded together in parallel and love it. I guess someone needs to just try both and see for sure. I can see advantages/disadvantages to both.