Been doing some added research on putting an intercooler in my '94. In some respects I'm wondering if I chose the right direction to head - materials wise.

I've gleaned over the two threads here on IC installs, as well as looking at a couple of other sites - forums and vendor, and a printed article I have on the install of a Turbonetics system in a 6.5 Blazer. For reference purposes here's what I've looked at and gathered info from:

myweb.cableone.net/tbogemirep/

dieselplace.com/forum/showthread.php?t=29834&highlight=intercooler

www.turbotechnologyinc.com/65_installation_instructions.htm

www.kennedydiesel.com > 6.2/6.5 Performance Parts > Intercoolers

www.turboneticsinc.com/ic_cores.htm

First, the 'original' 6.5 IC kit appears to be from Turbonetics. The IC core I'm guessing (as I have yet find listed dimensions) is about 20"w x 10"h x 3" d. Compare this to the Large IC core sold by Kennedy (Spearco) - 25"w x 6.5"h x 4x5d, and the IC core used by our own MrTailLight - 24"w x 12"h x 3"d. The Kennedy(Spearco) version and MrTs' version are both 'bar and plate'. It is unknown whether the Turbonetics used bar and plate or 'tube and fin'. From a volume perspective we have MrT @ 864 cu in; Kennedy/Spearco @ 731 cu in; and Turbonetics @ 600 cu in. (Understand that this is a physical dimension reference. I was to find flowrates for the Kennedy/Spearco IC only. Flowrate would have made for a better comparison.)

So here are some questions to ponder:

1) How much air flow (flowrate) or volume is required by the 6.5 Turbo?

2) Can an IC be too big or tto small?

3) For each of the IC,s how much of the actual IC core is out of the 'direct flow" of oncoming air? That is to say when looking at the front of the truck do you see all of the IC core or only a portion?

a) If you only see a portion, would a longer (l-dimension) but narrower (h-dimension) and deeper (d-dimension) be better in that it might expose more of the core to oncoming air.

4) Tubing size - is it best to keep the diameter the same as the turbo outlet and intake?

5) What are the pro's and con's for each - 'bar and plate' and 'tube and fin'?

6) What is an exceptable pressure loss across the inlet and outlet of the IC?

I'm not an expert on the subject but IMHO here are some of my thoughts:
Question #2 - size of the system would depend on what you wanted for cooling. You're probably looking for max gain so you would want a large area exposed to the air flow. The size of the air tubes can be too small and restrictive for your particular application and they could be too large and release the pressure built up by the turbo. It is probably mathmatically determined, and one of the parts of the equation is your question #1, how much does the 6.5 need to operate at peak power?

Question #3 - Kennedy/Spearco has a rubber air dam that hangs down to divert more air into the exchanger instead of just passing by under it.

Question #4 - I would say that you want the tubing to be the same as the turbo outlet and the plenum intake so you don't loose the pressure the turbo is giving you through machanical reasons.

Question #5 - Bar and plate would be a more robust design from a damage point of view, while tube and fin would give you a better heat transfer but more suseptable to damage by debris.

Question #6 - The amount of pressure loss, I believe, will be determined by the ambient air temp and the exchangers ability to transfer the cooler temps into the air inside the tubes, therefore causing the air to condense and this causes the pressure to drop. Acceptable drop would be the affect on the power produced by the charged air entering the combustion chamber. To counter act the pressure drop, if needed, the boost of the turbo should be turned up. The estimates that have I seen say 1 hp for every 10* of temp drop between the turbo and the intake plenum.

Now that I have shown how much I don't know are there any rebutals? Thanks for listening.

I also have been thinking about the intercooler for my truck. I heard from someone (I think Heath, correct me if I am wrong) that they are coming out with a liquid Intercooler for our truck later this year. So I was kinda waiting on it to see what it does in the real world before I make a decision. At the costs of these I can't afford both so gotta make the right decision the first time.

Just my thoughts.

I agree with you that 600 cu inches of Core is the best target to shoot for - of course more would be better. I doubt that an IC could be "too large" because more volume/size would only tend to bring the heated air back to ambient temperature. I also agree with you that keeping the tubing the same size as the outlet/inlet is desirable - larger size will not improve flow characteristics any appreciable amount.

I am currently trying to have fabricated an IC made of TWO Probe/MX6 IC's, attached end-to-end. If I succeed, the NEW IC will measurd approximately 26" x 13" x 2.5" thick, including the tanks. This "package" will be mounted between the frame rails at about a 45 degree angle with the road, and the inlet & outlet will be on the passenger side ( passing through the wheel well & into the engine bay). Total cubic core volume will be ONLY 450 cu. inches.

I have also bought (on Ebay) a small electric radiator fan, which I hope to mount on the INSIDE of the IC - pullling air up through it.

At this moment, I am unsure whether this is DO-able ? I have found a radiator shop who has attached the two Probe IC's together, but he is having problems welding the Aluminum to connect the tanks together. There are some of these Probe IC's on Ebay if you want to visualize what I am attempting.

I just noticed one point here that may have been overlooked. While the physical outer dimensions of the IC are a consideration, another consideration that nobody mentioned is the number of rows in the IC. Well, Willy kind of touched on it. Not only will this affect airflow, but it will affect efficiency. Think about it this way, if you have a 800 cu/in IC with lets say 20 rows in it, or a 600 cu/in IC with 35 rows in it of equal size to the ones in the 800 cu/in IC, which one would be more efficient? As long as there is still enough room between the rows for proper airflow, I'd go with the 600 myself. But, that's just my $.02;)

Which IC do you have FF?

I'm gonna bet that FF has the Turbo Technology/Turbonetics system. Just a gut feeling.

BTW, I spoke with Turbo Tech yesterday. Their core is in fact 18x7x3, which puts its volume at somewhere between 375 and 400 cu in - about 2/3rds of what I had originally estimated. It is the tube and fin design.

FWIW, I also spoke with a fellow that has a TT IC on his truck. He said that with minor exceptions it does the job well. One minor exception being when he was pulling a 7% grade for 6-7 mi with a heavy trailer - things did get a bit warm, but mostly the trans temp. Using this as a comparison for my needs, I think the TT IC would do me well.

wi65TD, you are right. It seems to work really well too. A little tight with all the tubing in there, but on the MT 2500 at 15 psi pulling a 6% grade for 2 miles my IAT was very respectable and my egt sat around 850. I can't remember what the iat was exactly so I won't even guess, but I do remember it was almost half what my friends non intercooled 98 was on a hill about 1 mile long same grade and no car trailer pushing 13 psi.

Well I opted for the Kennedy/Spearco. I've had it for a couple of weeks now but haven't got it installed yet. I did get the Heath PMD isolator moved so I could install the IC where it was but that took some thinkin' and bracket building. Anyway I'm having Randy's Offroad put it in for me this comming week and then the week after that I'll test it out taking the trailer to the coast down to the Long Beach / Astoria area. Couple of small hills to try it out on. Have to have a week around the house to test it out to see if the tubes blow off. When I get back I'll give you guys a report as to what I think.