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1991 Impulse RS (AWD Turbo) project car

900 Views 7 Replies 4 Participants Last post by  sno
I bought this Impulse RS a couple months ago, other buyers had backed out and I got it for 750 canadian, approx 500 US. People were telling me there's less than 100 of these left, and the seller was saying it was going to a scrapyard if it wasnt sold within the week, so I made it my mission to save this piece of automotive history. Neat little thing with a transversely mounted 1.6L 4XE1-W DOHC, water cooled & intercooled turbo, manual transaxle in the front with double-wishbone, isuzu 8-bolt diff in the rear with macpherson struts, viscous clutch transfer case RWD biased 57/43, and suspension tuned by Lotus.

What's wrong with it:

-The turbo and manifold blew, and a previous owner took the core parts so I have nothing to remanufacture.

-The lotus struts are blown, and it will handle very poorly in its current state. One previous owner sold it due to trouble finding new struts.

-Other things like the intercooler, EGR setup, radiator and fan, and AC are also missing. The interior is partly dismantled and the front seats are stained. Shift knob is missing

-A fuel leak when the pump is running. Previous owner had a fire start back there but evidently put it out before damage.

How I plan to fix it:
-I've heard from two or three people who say they have either remanufacuted or core turbos and manifolds for this vehicle, but after two months I haven't heard back. Instead I may need to make a custom turbo/manifold/exhaust setup, I'd likely do something similar to huy tran’s car on the isuzone page, he runs a dsm/Evo 3 16g. I'd like to keep the hood scoop functional, but it will be more practical and less restrictive / less piping to have the new intercooler in front of the radiator, so probably will go that route.

-My dad's neighbour, a retired locomotive turbo diesel mechanic and pretty good welder, (who is also kindly allowing me to store the implse in his barn), is very interested in the project and will be a great help in making sure I get any custom forced induction setup done correctly. DIY custom turbo manifold incoming most likely. Probably will get a machine shop to make the engine side flange and go from there.

-Once again relying on the ingenuity of others, it turns out that running springs and struts for a corolla works well for the front struts with a few small mods: strut retrofit = @adventures_of_aamir and possibly might even work for the rears although AFAIK nobody has tried it yet

-The rear struts are available from Japan (KYB) but I am going to try running the corolla struts in the rear too because it appears that it might work

-An interior carpet for a Geo Storm is available, with the main difference being the Impulse RS just has a hump for the rear driveshaft. That saves me from needing to do custom replacement carpeting

-I'll probably drop the fuel tank to find the leak, but I'm worried if the leak point isn't obvious I may have trouble with tracking it down. Repairing the fuel leak has to be priority #1

The good news!
-Very little rust for a canadian vehicle
-a classic japanese AWD turbo sports car that isn't a subaru or extremely overpriced?! sign me up
-The engine makes good compression
-Catalytic converters (I will sell these to fund the project because no emissions regs in this part of canada) and owners manual were included with the vehicle
-I managed to find an amazing deal on a new-old-stock Koyo rad, which appears to be the only aftermarket radiator that has dual cores like the OEM RS rad. Paid $105 USD, MSRP for the koyorad 1117 in 2001 was more than I paid for the whole car
-All the CV axles and boots are in great shape

More Pics:

I would have liked to have towed it home with my trooper w/ heavy duty springs but when I was rear ended the tow bar got bent and that's the one thing I haven't fixed yet.

I was worried these RS specific HVAC controls were lost too, but I managed to find them :D

More updates to come. . . . .
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Looks like a fun project.
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Wow! This thing is so cool - I'm happy you had the chance to save it. I had no idea these came in an AWD flavor! The blue is great, looks like it has good bones, and sounds like it'll be unique and well built when you're done with it. Looking forward to following along.
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You are one lucky guy -- I've been looking for one of these in a project form (to avoid paying 10k+) that isn't just completely rotted -- should be a blast to fix up. FWIW, they made 600 for the US and Canada. Last I checked, 131 were registered in North America. Best of luck, I can't wait to see what happens
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Ordered a used original turbo, after scouring eBay for the turbo listed under Isuzu Impulse and never finding anything, a helpful friend from the isuzone page did a search for Lotus Elan M100 SE turbo which had the exact same engine and bam! Found a used one in decent shape. So that's on its way soon, let's just hope it doesn't get lost in the mail like my workshop manual did.

Also, amayama has relisted the turbo exhaust manifold after they said it was unavailable a couple months ago, so I put in a parts request and fingers crossed it will be available to order new from Japan. Not gonna get my hopes up but I will be very happy if I'm able to order a brand new one ($432 canadian)
Also just wanted to say thanks for the supporting messages and I'm glad you all like this car too!

I've made some serious progress in finding parts. Aside from the turbo, I also ordered an exhaust downpipe / precat assembly from ebay as well.

Additionally, Isuzu Japan confirmed availability for brand new exhaust/turbo manifolds, and it is set to ship out by the 18th! Isuzu's legacy parts support is INCREDIBLE. A couple months ago I put in a parts request for the manifold. Unsurprisingly there were none available, but i retried 2-3 months and they have since actually cast at least two new ones (likely more), confirmed availability with me, and are set to ship it soon. Absolutely amazing. I've seen them do this with parts for my 93 trooper as well although that was for smaller things, but it seems like when they have ran out of supply in the main warehouse in Kanagawa they often make more new parts rather than discontinuing them like Toyota and Honda tend to do. I am SO IMPRESSED by this! They actually dug out the old moulds and made a new batch after I expressed interest in buying one. Amazing. Will definitely be posting pics of the nice shiny new manifold once it arrives

Now the next thing I need to do is fix the fuel leak and figure out my cooling fan situation
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Received my core turbo today, I was getting quite worried because Canada Post temporarily lost track of the package so today when it arrived a week past its recorded delivery date I was super happy! Almost thought I had a repeat of the workshop manual...
Called up a local turbo rebuilder and despite their surprise that an isuzu gasoline passenger car turbo exists, they ran the part number and confirmed they can get a rebuild kit. $890 CAD for the turbo rebuild, this core is overall pretty decent but the shaft bearings have waaay too much longitudinal play

Also received this wonderful email from Amayama a few days ago - lots of little bits and pieces, along with the brand new turbo/exhaust manifold have been shipped! Only a few weeks until that arrives

Amayama Trading Co.

We've just sent your order

TitleQuantityPrice, CAD
Isuzu 9095613240
Part number changed. New part number: 8970757550
Isuzu 8943360690 - THERMOSTAT
Isuzu 8944806892
TURBO HOSE; WATER, PIPE TO PIPE, B Part number changed. New part number: 8944806894
Isuzu 9095714120 - WASHER
O-ring, coolant pipe throttle body to tstat housing
Isuzu 0743106300 - SCREW
Front door armrest screw
Isuzu 0911501060 - NUT
Radiator flange nut
Isuzu 0280806160 - BOLT
M10 sway bar end nuts Part number changed. New part number: 0280506160
Isuzu 8944731601 - GASKET, METAL
Isuzu 8944740720 - GASKET, METAL
Isuzu 0911502100
Part number changed. New part number: 0911802100
Isuzu 0280808180 - BOLT
Ign coil bolts
Isuzu 0280808140 - BOLT
Ign coil bracket bolts
Isuzu 8944806880 - HOSE, RUBBER
Turbo oil return hose
Isuzu 9095714100 - WASHER
Turbo coolant I/O crush washers
Isuzu 1096750450
turbo water I/O banjo bolts Part number changed. New part number: 1096750810
Isuzu 9019606200
Rad tank mount bolts Part number changed. New part number: 0506406200
Isuzu 8944731565 - MAINFOLD, EXHAUST
Turbo manifold
EMS International (the 19th of May) 6.108 kg 193.61

And finally, my downpipe / precat assembly is also on track to arrive in just a couple days!

Now I just need to stop procrastinating on getting that fuel leak fixed...
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My shipment of OEM parts from Japan arrived this morning! Came much faster than I expected

Almost thought they forgot to ship my manifold, or there was a mixup in the parts numbers, since it was all so well packaged in there

Everything arrived perfect as usual. I'm continually super impressed by Isuzu Parts Japan/Amayama

Drove over to the turbo shop and dropped off the turbo for rebuild. Not sure when that will be done but hopefully less than a week

In the mean time I'm gonna continue chasing the fuel leak (need to drop the gas tank, I can tell someone has been in there before, non EFI rated hoses and the cheap worm gear style of hose clamps were used as replacements which could be part of the problem).
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