Intercooler Aux. Fan?

[joed]

I did a topic search and didn't really find anything specific, so...

Speaking of aux. electric fans, has anyone tried running an electric fan in front/behind the bumper mounted IC for lower speed towing?

I have Kennedy's big IC mounted in its usual behind the bumper-between the frame location and find it works really well if boost pressures are above 12 and speeds above 45. When towing, this equates to being in 4th gear (direct on my 5spd). I do tow fairly heavy, between 10-12k.

When I get on a long, steeper climb (7-8 miles at 7-8% grade) and have to use third gear, my boost will top out at 11-12 and speeds will drop to around 40. On my scanner, IAT will still climb to ~230 deg. F, which is still a lot better than the 300 I would see before the IC install, but obviously not the 50 deg. above ambient some report with an IC. It seems the IC gets heat soaked on these long climbs.

For this situation, I'm wondering if a smaller electric fan (10" dia. or so) could be turned on to help flow thru. the IC? Would the fan become more of a hinderance than help because when its not running it blocks the normal airflow thru the IC?

Also, most of these fans in this size seem to draw around 7 amps. Is that more than the stock alt. can handle?

Sorry for all the ?s. Thanks in advance.

Joe.

[More Power]

Is the OEM plastic air dam still mounted below the bumper? If so, this will deflect a lot of the air that would otherwise hit the IC.

If that's not it, I'd look at making an aluminum scoop that attaches to the IC to catch and direct more air through the IC core. With an IC mounted at an angle to the airflow (like these are), much of the air will simply slide off without going through. I'd do this before contemplating an electric fan.

Jim

[joed]

No air dam - truck didn't have one. In fact, I don't think I've seen a 8600 gvwr 3/4 equipped with one.

The IC does have a rubber flap mounted to its rear that extends down about 4 inches to act as a scoop. You can see a picture of it on JK's website...

Maybe my boost level is just too low - this is CO, and most passes are 9-10,000' elev.) I'm reluctant to try and increase it at higher engine rpms - GM's programming has it drop off at higher rpms to put less stress on the engine, perhaps?

Joe.

[ronniejoe]

It's actually more of a turbine housing flow problem. The GM turbine housing cannot flow enough mass at high engine rpm to keep up and chokes. This causes high back pressure and high egt.

The programming does reduce the wastegate duty cycle up there, but even with the actuator running straight off the pump, boost falls off at higher engine rpm.

[joed]

Okay, that's making more sense now.

How about timing, would there be a benefit to changing the programming to increase the injection timing at the higher rpms? It seems the EGTs get lower with more timing.

I may still try the fan idea - seems like it would help with heat soak issue on the longer climbs.

Thanks. Joe.

[Robyn]

Ron
Can one use a different set up and rebuild things with a different down pipe to get rid of the bottle neck that the GM housing has??

How well does the Banks setup flow when asked to go beyond its design criteria??

[keplinger78]

No air dam - truck didn't have one. In fact, I don't think I've seen a 8600 gvwr 3/4 equipped with one.

The IC does have a rubber flap mounted to its rear that extends down about 4 inches to act as a scoop. You can see a picture of it on JK's website...

Maybe my boost level is just too low - this is CO, and most passes are 9-10,000' elev.) I'm reluctant to try and increase it at higher engine rpms - GM's programming has it drop off at higher rpms to put less stress on the engine, perhaps?

Joe.
My 93 2500HD 4x4 8,600 gvwr has a airdamn with fog lights,It's Silverado cab and chassis,not a Pick-up,well it's an 8ft bed.It was a utility bed truck from GM now it's going to be a welding truck.
Later Tom K

[joed]

Well, after doing some measuring, it looks like the biggest fan that will fit over the IC core area is a 7-inch diameter. I've found one that's rated at 400 cfm.

For those that know more fans than I, is this enough to do anything? It would have to be installed in a 'pusher' fashion.

Also, any thoughts on which side of the IC - hot or cold side?

Thanks again.

Keplinger - interesting on your truck about the air dam. Maybe it's something they dropped on later model years. I know my dad's 95 doesn't have one either