This is the original Impulse IC after cutting the end tanks off.

The IC is an air/air unit and is the wrong form factor for me to use as an air/water unit.  The core was cut in half to give two smaller cores for the air/water unit.

This shows how the two smaller cores will sit as an air/water unit.   The water will flow through the cores.  The charge air will flow through the face and fins between the cores.

These are two of the composite end caps I made up.

Testing the positioning of the IC with the mocked-up end tanks in place.

This is the oil pressure line source.  It uses the same tap that the Impulse did and matches it to a standard 10mm banjo.

The braided steel oil pressure line with a piece of rubber hose over it to prevent chaffing.

Yet another test fitting.  This one with the spacer in place and after polishing up the heat shield a bit.

After talking a bit about it and how to make it work, I was convinced that it'd be best to draw the air the opposite direction so it'd be exiting the scoop instead.  To make it work however, I'd need a rather complex scoop design so that it'd still draw cool air through the IC instead of hot engine air.

After that, I decided to work on an air/water IC unit.  It has the disadvantage of more complexity to add the water lines, pump, tank and front heat exchanger, but it has the advantage of keeping the intake air duct volume to a minimum and the IC core can be much smaller than a comparable air/air core would need to be.  This makes it easy to mount the IC above the engine and give the intake charge a strait shot from the turbo, through the IC and into the throttle body.  I will also have to fit a front mounted heat exchanger for the water, but this will be much easier to do than fitting the thick IC core there with the associated plumbing.

I had intended on using two Impulse ICs in parallel for my air/air setup.  Since I'm switching to an air/water setup, I'm just going to use one of them now.  The core was cut in half and each half was rotated 90°.  Where the charge air used to flow through the cores in the air/air setup, the water will now flow.  The charge air will now flow through the face and cooling fins of the cores where the cooling air did in the air/air setup.

I don't have the ability to weld aluminum right now, so I toyed with the idea of making the new end caps from composites and epoxying them on.  I made some up using materials I had on hand from building my RC airplanes.  I'm not sure how these will hold up though.  I need to find someone who knows a lot more about composites before I try this for real.  I don't really know what they can and can't do, or what are the best materials and epoxies to use.  At the least, they'll serve as good patterns if I take them to a fabricator to make out of aluminum.

I also made the oil pressure line for the turbo.  It takes the oil from the oil gallery on the passenger side of the block using the same tap that the Impulse did.   You'll want this as well as it's a weird metric tapered thread similar to pipe threads.  You can also get something like this from AutoMeter.  They sell a package that converts several different metric threads to stander 1/8" NPT to hook up their gauges to European and Japanese cars. 

I also put in a tee connector so that I can hook up an oil pressure gauge just before it goes into the turbo to monitor it if I want.

The oil line itself I made from Earl's parts.  I had used them for my rear brake lines after my lift and was happy with them and their selection of oddball pieces and adapters so I used them for this too.   The line runs under the engine so I slipped a piece of rubber fuel line over the hose to keep it from chaffing against the engine block or anything else it may contact.

I also did another test fitting of the turbo with the spacer in place between the exhaust manifold and the turbine in order to position the oil return line.  I polished the heat shield up a bit while I was at it.  The water lines are worked out as well, but I won't do those until I actually put the turbo on as I'll have to drain the coolant to do so.  I still have to make a new elbow for the compressor inlet as the stock TurboCoupe one is at the wrong angle to work.

Finally, around mid Dec, I'll have a second car to drive for about a month so that's the target for putting the turbo on.

This is the new water line with the two taps for cooling the turbo.

You can kinda see the EGR tube in this picture.  It's just a slip fit (no clamp) with about 1" of overlap.  It hasn't leaked and I can still get it out if I have to pull the manifold.

Here's a view with the oil pan removed.  The oil return fitting is threaded into the small hole in the casting on the right of the picture.

Here's a view from the top showing the oil return fitting on top of the oil pan casting.

Here's a view before drilling and tapping the casting.  You can also see the stock EGR and coolant pipes before modification.

This is the dipstick tube and brace after bending it into it's new Z shape to clear the turbo.

Here's another view from underneath.  The tee on the left is the oil supply line.  One for the turbo and the second for an optional gauge or maybe a secondary backup Hobbs switch to cut off the fuel pump if oil pressure drops (i.e. plugged or leaking turbo oil supply line) to prevent damage to the turbo.

I drained the radiator of coolant and started on the water lines for the turbo.  This wasn't too bad.  I changed my mind 4 or 5 times in the process until I came up with what I did.  The lines tap into the hard water line that runs along the driver's side of the block.  By cutting that line up and combining it with some bends cut from the Impulse line, I finally came up with the new one that had the water line taps in it and is out of the way of the exhaust elbow coming from the turbine.

I also had to cut the EGR tube behind the head and connect it to the end of the EGR tube from the Impulse to hook it up to the manifold.

While I had the radiator drained, I took a closer look inside and noticed it was only a single row core.  I know Isuzu made a double row core so I thought about getting one of those to alleviate my cooling problems I've been having in the desert heat.  In the end, I had a local shop re-core my radiator with a new high effeciency 3 row core instead.  They added a nipple to the upper tank for the turbo coolant return line as well. 

While I was at it, I redid my electric fan by placing it in a slightly different position in the shroud and closing in the gap around the blades for better flow.   It's kind of a cheesy temporary job right now made with balsa sheets and duct tape.   But, knowing the fine qualities of duct tape, it may very well end up being permanent.

I pulled the oil pan and drilled and threaded a hole for the oil return line.   Kind of interesting to look up into the internals of the engine.  The crank and rod ends looked massive for such a small engine, but I haven't seen many others to compare it to so it may be very normally sized.

The oil dipstick was in the way too.  I had to rotate it about 90° and put another bend in it making it rather 'Z' shaped.  It now clears the turbo and looks like it'll have enough air space to not get too hot.  I can always add a heat shield around the tube later.

To make it work, I also had to weld a flange to the base of the tube for the bolt to secure it to the block and make a new support bracket for the tube as well.

I gave the manifold, my 3/8" spacer, the turbine scroll housing and the exhaust elbow a shot of high-temp exhaust paint prior to final assembly.  They had each been covered with a ceramic coating that resists to 1800° - 2000°.  The final coating is resistant up to 2500°.  Time will tell how well this stuff works and if I applied it correctly.

Hooking the exhaust elbow up to my current exhaust was supposed to be a simple manner, but it ended up leading to a complete re-do of the exhaust system (again).  I took off the HUGE muffler (the thing looks like it belongs on an RV) that I put on because I was sick of the loud turbo muffler I had and replaced it with said loud turbo muffler.   I think it'll be much better this time because of the turbocharger and the addition of the new cat I put into the system a while ago.  I don't think noise will be a problem.  It also fits much better underneath the truck being much shorter.

All this took about a week and a half maybe.  Everything is hooked up now (oil, water, exhaust, EGR) except for the induction hoses.  The hoses from the compressor to the throttle body were pretty easy.  It's not very pretty, but it's temporary until I get the intercooler in.  Hooking the compressor inlet to the MAF and air filter though is being a pain in the a$$. 

I really need a good tubing bender and this would be easy.  As it is, I'm doing it the hard way cutting and welding elbows together to get the right angles.  Making flanges to bolt to the compressor and MAF has been a pain as well.  Doable, it's just taking a while.

Finally, the last step is to work out the vacuum hoses.  Some I know will need check valves, some need to be run upstream of the compressor and some are fine where they are.  I still need to figure out what needs what.  After that, I'll be ready to test fire it.

Pictures will be coming soon...

Right now, it's set up to keep the max boost at it's lowest.  I seem to be topping out around 6 psi, but it's hard to get there because the clutch slips so bad.  I've hit that only once or twice.  4 or 5 psi seems to be the norm.  Mathematically, that equates to about a 40 - 50 hp boost if I can keep it all the way to 5000 rpm.  7 psi @ about 5000 rpm would be about 60 hp.

The clutch has been going for several months now.  I bought a new CenterForce DualFriction clutch a couple months ago with the intentions of installing it before the turbo, but that got delayed.  It's on the priority list to get done now.

I just did some seat-of-the-pants testing in different gears starting at about 1500 rpm.  If I floor it, I'm *almost* in boost by the time my foot hits the floor and it rises rapidly from there. If I start above 2000 rpm, lag is almost non-existant.   Depending on the gear, the boost stops rising the the rpms shoot up about the time I hit 3500 rpm from the clutch slipping so badly. It's actually worse in higher gears and it slips at a lower rpm and boost level in 5th than it does in 3rd. By feathering the throttle, I can keep a pretty constant accelleration going at somewhere around 3 psi without the clutch slipping.  Anything over that and the clutch slips freely within a second or so.  Also, when I'm cruising and I floor it, I've noticed that boost comes on faster if I'm in a higher gear.  "Turbo lag" is more noticible in 2nd than 4th or 5th. 

So, I have to take it easy driving it. Anything over half throttle quickly leads to clutch slipping. It's way cool though to be cruising along in 4th or 5th then nail it and accellerate harder (for a couple seconds anyways) than if I had downshifted one or two gears. It actually seems to make it much easier to drive as I don't have to shift so much.

I also added a compressor bypass valve (commonly refered to as a "blow-off valve" or BOV).  It's a Bosch part from a turbo SAAB.  Initially, whenever I shifted it let out an awful noise as the boost backed up into the compressor when the throttle plate shuts.  It could be minimized by slowly letting the rpms and boost drop before shifting but it was a real pain.  With the BOV in place, I can shift like I want with no problem.  All I hear is a slight "pffftt" as the pressure bleeds off and then only if I don't have the radio on.

In my case, I fed the blow-off air back into the compressor inlet.  This helps to keep the turbo spooled during the shift and I don't get a rich spike that dumping metered air (it's already gone through the MAF sensor) overboard would.

Also, no intercooler yet.  I've got a core put together for an air/water unit, but I'm also thinking of something else a little more exotic than air/water.  I may also be able to get one of those ERL Aquamist water injections kits to test out as well.   That'll all come in time, but I think I'm just going to take it easy for a little while and enjoy it.  It's been almost a month since I've driven it.

I also want to get some good instrumentation (temp sensors, fuel pressure, oil temp, etc) so that I can really monitor things and measure the effectiveness of the IC and water injection when I start pushing it.

Incidentally, I'm still running 87 octane fuel and I haven't noticed any pinging or detonation even when I hit 5 or 6 psi, but I haven't hit this over 3500 rpm yet and even then it's only for a second or less due to clutch slippage.  I still haven't had it out on the freeway yet for high speed testing either.  Frankly, I'm not sure I even could with the clutch in the condition it is.  That'll be the place to test boost at higher rpms and to listen for knock.

Oh, and BTW, in case you're wondering.  No, this is not for, nor do I intend it to help (very often anyways) in off-roading abilities.  I do mostly the slow crawling stuff so forced induction won't really help. The Amigo (and all the Isuzus for that matter) are excellent and have all the power needed for slow off-roading.  I just want better on-road performance.  Now if you're a mudder or a high-speed desert runner, that's a different story...

After my fueling is figured out and I'm able to floor it from off idle, I'll really be able to see what's going on.