Intercooler in an FSJ sporting a 4BTA

[Carleysjeep]

I Personally, I think this shot looks bad @$$:

Heck Yeah!!!!!!!!!!!!!!
With something like that you don't even need a grill.

[zmjeeps]

Heck Yeah!!!!!!!!!!!!!!
With something like that you don't even need a grill.

Just to keep the birds out...

Thanks for all the kind words guys. I didn't mean for Hankrod's stuff to get posted and then put down. Anyone who can do a set up like that is OK in my book. I'm sure there is a reason for the 2 intercoolers, hopefully we find out what that is.

Mikel, Couple more questions for you. You have a 'hump' hose on the turbo side of the intercooler, should there be one on the other side too? The reason I ask is, the set up I took off a 6bt only had one hump hose and it was on the engine intake side. Didn't know if one side or the other was right, or if it should be 2...

Just me in uncharted waters again...

Still turns my stomach that I have to do all the cutting on the NOS sheetmetal.

Zack

[Mikel]

Mikel, Couple more questions for you. You have a 'hump' hose on the turbo side of the intercooler, should there be one on the other side too? The reason I ask is, the set up I took off a 6bt only had one hump hose and it was on the engine intake side. Didn't know if one side or the other was right, or if it should be 2...

I put that there to compensate for a bit of misalignment in the piping. The rubber elbows didn't give me the exact angles I needed. I may add one in the other side, to help dissipate some of the engine vibration and keeping it from stressing the intercooler too much.

[zmjeeps]

I put that there to compensate for a bit of misalignment in the piping. The rubber elbows didn't give me the exact angles I needed. I may add one in the other side, to help dissipate some of the engine vibration and keeping it from stressing the intercooler too much.

That's what I was thinking, one in either side for engine vibs. I got a piping 'kit' with a bunch of straight pieces, 90s and 180s of alum pipe and a bunch of silicon connectors so I'm going to try to pipe it all together witout having tig the alum pipe. We'll see. It also has some 90 deg and 45 deg silicon hose pieces. Here's a pic of the kit...




Zack

[zmjeeps]

I used 90 deg silicon elbows to go from the ends of the intercooler through the radiator support. Should be straight shots to the engine and the turbo after that...

Zack

[budojeepr]

I don't have room for an intercooler in front of (or behind) the radiator, since I moved my rad forward to clear the GM 6.5. I like that angled one in front of the axle though. Any thoughts on its effectiveness? I assume the airflow would be much less...

[zmjeeps]

I don't have room for an intercooler in front of (or behind) the radiator, since I moved my rad forward to clear the GM 6.5. I like that angled one in front of the axle though. Any thoughts on its effectiveness? I assume the airflow would be much less...

Got any pics of what you did? How far forward did you have to move the radiator? I've got room for the 3" thick intercooler, the A/C condensor, and an alum rad and none of it sticks out past the stock radiator mounts. I was actually surprised how much room was between the grill and the radiator mount.
If your are using a full width grille (razor or later) you can cut out some of the sheetmetal on the front valance and move the intercooler even further forward than I have it. I was just trying to do it wthout cutting the front valance.

Zack

[Hankrod]

The reason for the two intercoolers is, intercooler flow restiction. A good or effective intercooler will cause a pressure drop. Pressure drop requires more pressure at the compressor and causes more heat, do you see a repeat of events? The correct answer is to provide enough surface area for the compressed air to flow through with a allowable pressure drop. I calculated that my 401 needed 72 sq. in. of intercooler flow surface area to allow < 2lb. pressure drop @ 6K rpm. Been allmost three years and I feel its setup correctly. Hankrod

[zmjeeps]

The reason for the two intercoolers is, intercooler flow restiction. A good or effective intercooler will cause a pressure drop. Pressure drop requires more pressure at the compressor and causes more heat, do you see a repeat of events? The correct answer is to provide enough surface area for the compressed air to flow through with a allowable pressure drop. I calculated that my 401 needed 72 sq. in. of intercooler flow surface area to allow < 2lb. pressure drop @ 6K rpm. Been allmost three years and I feel its setup correctly. Hankrod

Like I stated before, I wasn't throwing rocks are your design or setup, just didn't understand the thinking behind the 2 intercoolers. Just out of curiousity, what formulas did you use to get the 72 sq in at 6k rpm? Is it base soley on air flow to the engine or ??? Thanks,

Zack

[Hankrod]

Zack, no problem and I know that I'm a bit short on my replies. The formula I used was from Corky Bell's turbocharging book. I would restate it now, but I loaned it to someone...... and now its gone. I recall it to be a basic formula based on the internal fin count of the intercooler tubes and there flow rate. Hankrod

[zmjeeps]

I was playing around with these:


For your 401 assuming 85% VE, 6000 RPM CFM= 591.75 CFM
For the 4BT (3.9L) 238CID, 90% VE, 3000 RPM CFM= 185.94 CFM

So we know how much air it needs, but I'm not having much luck finding the formulas for temp drop vs core size or pressure drop vs core size of an intercooler. I know PV=nRT, so I know the two are related, just trying to double check what I've done. I've been searching around the net without much luck. (Any one else can chime in here too).

Zack

[billyrb]

Zack, if you don't already have it, that book Hank mentioned is the turbo charging & intercooling Bible. I got mine for about $10 on ebay a while back. If you don't have one and don't want to buy, I can dig mine out and find the formula for the intercooler if that helps.

[zmjeeps]

Thanks man, I'm trying to make this thread a good resource for anyone looking to do an intercooler on an FSJ, for whatever turbo motor they would be using, so if you could post the info in this thread, that would be great. Thanks,

Zack

[Hankrod]

Hi Zack, I have the answer from ' Maximum Boost' by Corky Bell. Basically for every 500 cfm of air flow you will need 25 sq. in. of intercooler core flow area. Now at 14.7 psi of boost a engine can double its displacement flow. So if my 407 can flow 1400 cfm @ 14.7 psi it will need 70.65 Sq. in. of flow area. Many more veriables involved but thats about it. Hankrod

[JeepinPete]

I was going to use an intercooler out of a Dodge Sprinter van:



It fit in between the outer facia and the inner sheetmetal. It is rather thin, maybe an inch thick, but spans the entire opening. The 90* turns are part of the intercooler itself. It has to be mounted low to clear the hood latch.