If I install an intercooler off an 85 244Ti onto an 81 242 GLT and just leave the actuator hose set up stock like it came on the 81, how much horsepower will be gained. (No change in boost PSI, just cooler air to the intake.)

I plan to add a manual boost controller later on. I've heard that the manual controller can simply be inserted into the actuator hose. If I do it this way, what boost pressure should I set it at? I don't want to push the limits of the system. I want the engine to be fun to drive, but I want it to last.
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Thanks everyone for all the help, Doug C. 81 242 Brick Off Blocks, turbo bars and wheels, M46; 86 244, B230, 150k , auto.

I've heard different opinions about installing the manual boost controller on the 1981 in the short factory hose that runs from the pressure side of the turbo to the actuator. This would mean eliminating the long hose from the driver's side IC hardpipe over to the actuator. (That's how it was set up on the 1985 donor.) It would also mean capping the nipple on the driver's side hardpipe and plugging the vent hole on the passenger side hard pipe. This seems like a cleaner layout, but I've heard different opinions. Anybody want to kick in their views on this?
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Thanks everyone for all the help, Doug C. 81 242 Brick Off Blocks, turbo bars and wheels, M46; 86 244, B230, 150k , auto.

On the old '85 244Ti I ran a G-Valve in the long hose, on the '92 745Ti I had it in the short hose, the short hose seemed to provide the best most consistent control, very little difference at all really and the difference could well be accounted for by the totally different equipment.

As to intercooling the car, cooler air at 6psi will be denser and therefore provide a bit more power than hot air at 6psi. As the air goes through the intercooler it will become denser, this is simple physics. The bottom line is 6 psi of cool air is way better than 6psi of 200º air.

With the short hose you have the wastegate measuring the pressure from the hot side of the intercooler and it will also measure the pressure loss across the intercooler, all in all with the cooler intake air it may be a wash. In the short term I world run a long hose from the nipple provided in the new intercooler hoses and that way measure the actual boost received by the intake manifold.

When you get your boost controller you can plumb it any way you want and adjust the actual boost at the manifold with the controller. You do have a calibrated boost gauge don't you? This is the first thing you should get!
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Dave Shannon
Spring Valley, California
'67 1800s
'73 1800ES
'88-240
my pages

No calibrated boost gauge yet. Before the install, I will be buying that and the manual boost controller. So, you are saying that, regardless of whether I plumb the manual boost controller before or after the intercooler, it won't matter that much because I'll be setting the boost controller according to the calibrated boost gauge on the dash which measures boost at the manifold itself? Do I have this right?
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Thanks everyone for all the help, Doug C. 81 242 Brick Off Blocks, turbo bars and wheels, M46; 86 244, B230, 150k , auto.

My geuss would be zero. Even if you drop the temp, there is no volume change and the O2 entering combustion is unchanged. It is a closed system in the IC/intake. The only point of the IC addition is the allowed increase in boost you can make.

The boost will be very low if you leave it stock, beacuse there is a pressure drop of a few psi across the intercooler. With this setup you might get more power on a hot day than before, but on colder days it would not be as different beacuse the actual boost would be lower. For example, stock you would be around 7psi (non intercooled) but with an intercooler it could drop to say 5psi, so you would be getting cooler air but at a lower pressure.

Once the boost controller is added you should stick with about 10psi at first. This will give a noticable HP gain and is in the safe zone.

Also with an intercooler the boost comes on slower (lag) due to the larger distance and volume from the turbo to the intake.

Personally I would wait to install the intercooler until you get a boost controller. The intercooler install is a bit of a project, and you have to run the lines also, so it makes it easier to do it all at once.

I can still remember the exact day (about 4 years ago) when I first installed the new turbo and and added an intercooler. The first test drive gives you a whole new appreciation for the car, and makes you wish you had installed it earlier.

Good luck,


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Zack Silver 83' 242Ti (221k)