ATTN: SCOTTIEGNZ

[SHANE]

i understand you might have some pros and cons about the NPR intercooler's. i have two of them (the big one and the small one) and was planning one using one on my car. i will be running 25-30 psi through it. my spearco is just too small. so, am i wasting my time with these I/C"s or not?

 

thanks

[Scottie-GNZ]

Shane,

 

I hit a brick wall with the large NPR at about the 400RWHP range. Your 11.6 @ 116 puts you in the 350rwhp range and if you plan to turn up the wick to 25-30psi, that should put you in the 400+ range. Of course I am guessing since I do not know the details of your setup.

 

My advice is to not use the NPR. I have never seen any published flow numbers for the NPR or any OEM I/C for that matter. Ironically, a lot of folks are using OEMs that seem to be working fine but probably have major pressure drop. As a rule of thumb, you want 1.5cfm of flow for each HP before you start getting pressure drop and you probably want a 20% margin of safety when you are running that hard. That would make 400rwhp require 750cfm. What Spearco model are you running? There are very few Spearco models that flow less than that.

 

Look at this list: http://www.spearcointercoolers.com/stdcores.htm

[SHANE]

well the closest they have to my model(mine is 4 years old) is 2-225 700cfm. i still think it is too small 9x14x3.5" i guess i will shop around then for a better I/C. i was afraid of the NPR cause of the thickness. here are some flow tests on NPR I/C's from turboford. in case anyone is interested.

 

DRHausee has an awesome program for calculating all of this. He is currently in rev 2 of the program. I have his first version and this is what I calculated:

First of all, some constants: Compressor efficiency is 71%, compressor inlet pressure is 14.7psi absolute, compressor inlet temp is 80°F and intake manifold pressure is 20psi. This is for a 2.3 with VE of 75% at 5000rpm.

 

Starion IC : (the bigger one) at 324cfm and 292°F on the inlet side of the IC, the pressure drop is 0.29psi. The outlet temp is 139°F, heat rejected is 52287 BTU/hr, and the calculated heat exchange area is 1217 square inches.

 

Saab 9000 IC: at 332cfm and 295°F on the inlet side of the IC, the pressure drop is 0.81psi. The outlet temp is 123°F, heat rejected is 60350 BTU/hr, and the calculated heat exchange area is 1602 square inches.

 

Volvo IC: at 331cfm and 293°F on the inlet side of the IC, the pressure drop is 0.55psi. The outlet temp is 126°F, heat rejected is 58809 BTU/hr, and the calculated heat exchange area is 1539 square inches.

 

So it appears the Saab 9000 IC is slightly better than the Volvo.

 

Now lets look at the Dual Volvo IC (like mine) : at 340cfm and 291°F on the inlet side of the IC, the pressure drop is 0.29psi. The outlet temp is 94°F, heat rejected is 73063 BTU/hr, and the calculated heat exchange area is 3077 square inches.

 

I am not sure that these numbers are correct as Don's program looks at the numbers enters as being a single core IC. When the outside air hits the second core passing through, it is much warmer than the front row, so the numbers seem a little optimistic.

 

Now lets look at the Isuzu NPR medium duty Truck IC http://www.turboford.org/npric/ :

 

The smaller NPR IC: at 329cfm and 290°F on the inlet side of the IC, the pressure drop is 0.09psi. The outlet temp is 130°F, heat rejected is 55553 BTU/hr, and the calculated heat exchange area is 1404 square inches.

 

The larger NPR IC: at 340cfm and 290°F on the inlet side of the IC, the pressure drop is 0.07psi. The outlet temp is 111°F, heat rejected is 64237 BTU/hr, and the calculated heat exchange area is 2018 square inches.

 

Gentlemen! I think we have found a new intercooler! The big one (look at the attached link) is sweet! It will fit right in front of the ranger radiator, which makes it a great fit! Forget the starion, that thing is a turd. Now the downfall...the price, these things go for $250-300 on ebay.

[Scottie-GNZ]

Re the NPR, I think he likes it . The one he has listed as the "Big I/C" is what I refer to as the medium NPR. Here is pic of the medium and "LARGE" NPRs for comparison. The Large one is what I used up to 400rwhp. As you can see, the Large is taller but also has bigger tubes for more flow.

 

 

As for the Spearco, do not judge what a Spearco can do by its size. 700cfm can support 460+hp w/o a margin, so that is a pretty damned good I/C you have there.

 

BTW, in case I did not say it, 11.6 at 5800' is FLYING!!!