83 L-body conversion from carb to SMEC questions

I've always sworn I would leave my Scamp carbed, but recently I've come across most of the parts needed to put a turbo motor in it, and after driving my Daytona for a year, I am officially addicted to boost!:eyebrows:

With that being said, I wanted to ask for advice from anybody who has converted an early L-body over to SMEC. What are the pitfalls? I have FSM's for both 83 & 89, so I know I can work out the wiring. The SMEC & harness are coming out of a P body. I know a lot of folks recommend using a mini harness, but since the 83 & earlier cars wiring is WAY different than 84+, I really don't think it's going to matter. My plan right now is to drive the truck as-is this summer, and start the conversion over the winter when I don't drive it anyways, so I have some time to gather info.

I've read a lot of conversion threads, so I'm prepared for most of the issues(I think). I know I have to get a TBI sending unit and install a turbo pump, unless I mount an external Walbro 255. I know I have a TON of wiring to splice. Just hoping for some guidance on what other have found/done to make this go as smoothly as possible.:)

I would probably install the SMEC as practically a 'standalone' from the rest of the car. It doesn't really need to interface with anything inside the car besides the ignition switch unless you're trying to do cruise functionality or something like that. I would pare down the p-body harness to go straight from the SMEC across to the engine (like the V6s do) instead of around the firewall, and when you're ready to do the swap you can basically drop in the wiring and only have to hook it to your battery, ignition feed, and wire the fuel pump.

Just my .02, but as ive gotten more and more comfortable with wiring over the years i see less and less point to the way the wiring is typically handled on turbo swaps as a whole engine bay harness. I've done a drop-in van-to-van harness swap (on my TBI-Turbo van) and i've modified a van harness for my Aries and been involved with Strax22's impressive merge of an SMEC harness with the PDC and body control module of a 95 Caravan so i've seen it done many ways and my opinion at this point is it's actually easier to add only what's necessary to the wiring you already have than to try to modify a harness from a completely different engine bay to replace a bunch of wiring you have that already works.

Very good points. The truck hasn't had working cruise in years, so that really doesn't bother me. If I leave that off, do I need to worry about a VSS signal at all? Being an 83, the Scamp is a mecahnical speedo, so I don't need one from that perspective. It runs the old style voltage regulator on the firewall, so I don't really need the SMEC to control that either... I would like to run a check engine light inside so it's easier to check for codes, but that should be very easy. All the emissions crap was removed a long time ago. I really only need to run boost & baro solenoids, MAP sensor, and all the sensors on the engine. I need to sit down with my wiring diagrams and start mapping this thing out...

When I did my 1983 Rampage I also used a 1984 and newer dash complete, along with a 1988 Omni 50 pin dash harness.

Makes the bulk head connector 1989 Caravan compatible and possibly also 1988 LeBaron.

Another I spliced the P body harness to the 40 pin bulkhead.

iturbo converted an Omni TBI harness to turbo, which probably fits the Engine bay easiest.

Fuel filter is a slight issue due to leaf springs, I mounted mine up front for easy access.

One more to go, if I live long enough, deciding which way to try this time!!

Good luck, keep us posted.

Thanks
Randy

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Originally Posted by GLHS60

When I did my 1983 Rampage I also used a 1984 and newer dash complete, along with a 1988 Omni 50 pin dash harness.

Makes the bulk head connector 1989 Caravan compatible and possibly also 1988 LeBaron.

Another I spliced the P body harness to the 40 pin bulkhead.

iturbo converted an Omni TBI harness to turbo, which probably fits the Engine bay easiest.

Fuel filter is a slight issue due to leaf springs, I mounted mine up front for easy access.

One more to go, if I live long enough, deciding which way to try this time!!

Good luck, keep us posted.

Thanks
Randy

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Thanks for the info Randy. I was hoping you would chime in knowing you've done one. I really want to keep the interior stock, and have what's under the hood speak for itself. In fact, I'm planning on keeping the 4 lug rims just to mess with folks...

Here is the tentative combo so far:

Common block 2.5TII
Ported head
2 piece intake
ported exhaust manifold
FWP S50 large turbo
P-body wiring harness & boost button ECU
TBI or FWP F-3 cam
Hoping to find an A-520 with a 3.50 FD. With the torque of the 2.5, I don't need low gearing. With the 520, I can still keep my stock shifter... Next step would be an A-523 with the 3.50 FD like I put in my Daytona, but I would need to figure out a shifter....

I know some people who are going from auto to 5spd probably figure they might as well go for the 'better' 523/568 stuff but i've owned 520/555 and 523/543/568 (yes all 5 of those) and i've never driven a 520/555 and thought to myself "i wish i was driving the newer style trans". I would stick with the older stuff to avoid shifter complications.

I'm gonna be the first and only to say: Why not keep the 767 cam for the turbo build? :evil:

Also, if you're going to run any 'not strictly necessary' wires into the cabin may i recommend you extend/relocate the scanner connector into the cabin? I've gotten very tired of driving around with wires routed in through my window and having to be careful not to pinch my scanner cabling with the hood/door. I have my scanner's extension cable semi-permanently routed into my van through a hole i made in the firewall for the express purpose. Although there is a bluetooth datalogger in the works that may remove the need for this.

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Originally Posted by Vigo

I know some people who are going from auto to 5spd probably figure they might as well go for the 'better' 523/568 stuff but i've owned 520/555 and 523/543/568 (yes all 5 of those) and i've never driven a 520/555 and thought to myself "i wish i was driving the newer style trans". I would stick with the older stuff to avoid shifter complications.

I'm gonna be the first and only to say: Why not keep the 767 cam for the turbo build? :evil:

Also, if you're going to run any 'not strictly necessary' wires into the cabin may i recommend you extend/relocate the scanner connector into the cabin? I've gotten very tired of driving around with wires routed in through my window and having to be careful not to pinch my scanner cabling with the hood/door. I have my scanner's extension cable semi-permanently routed into my van through a hole i made in the firewall for the express purpose. Although there is a bluetooth datalogger in the works that may remove the need for this.

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Thanks for the suggestions. A 520 is my first choice. In fact, I've found a salvage yard not too far from me that claims to have 3 of them... I like the way the 523 shifts in my Daytona, but I'm like you. I don't get in my Scamp and think "boy I wish I a 523 in this." My 525 is a sweet shifting trans. Never had an issue with it. But I know it won't put up with the power I want to make. I'll scatter parts all over the road if I leave it behind the 2.5 I'm planning....

Never really thought about trying the 767 cam in a turbo motor.... Interesting idea... The 2.5 I'm getting is a short block, so I need a head. I've actually considered putting the G head from my Scamp on it. I know I'll need to change exhaust valves, but it's ported, and makes the 2.2 run really strong... Hmm... install that head, and leave the cam & PT lifters in it....:eyebrows:

There have been a lot of negative comments about the 2.5/ghead combo over the years, but i can't recall ever hearing of anyone doing any real dyno tuning to find MBT before complaining about how difficult it is to find a good timing curve, so who knows. I do know that a stock 2.5T1 (782 head) setup with an intercooler can be tuned to run past 15psi on 93 octane and can make well over 300wtq at that power level, which feels insane in a light car (my aries dyno'd ~312wtq and weighed similar to your rampage). Honestly it's way more torque than you could ever hook on any kind of street tire you could run on those 4-lug wheels until 60+mph. I think having a bigger cam and turbo will help your power delivery to make it more manageable. It will be a riot.

On my 2.5 van i have a basically stock 2.5t1/mitsu setup with an intercooler and 6* of cam retard on the stock cam, and it still breaks my 25" street tires loose in 2nd when it spikes to 13-15psi so even that level of cam retard isn't killing mid-rpm torque enough to quell wheel spin. It will spin in 3rd on a lumpy road.

So what are you going to do with your carb engine, anyway? I am planning to build a 10:1 2.2/ghead combo myself.. to turbo! With a big cam!

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Originally Posted by Vigo

There have been a lot of negative comments about the 2.5/ghead combo over the years, but i can't recall ever hearing of anyone doing any real dyno tuning to find MBT before complaining about how difficult it is to find a good timing curve, so who knows. I do know that a stock 2.5T1 (782 head) setup with an intercooler can be tuned to run past 15psi on 93 octane and can make well over 300wtq at that power level, which feels insane in a light car (my aries dyno'd ~312wtq and weighed similar to your rampage). Honestly it's way more torque than you could ever hook on any kind of street tire you could run on those 4-lug wheels until 60+mph. I think having a bigger cam and turbo will help your power delivery to make it more manageable. It will be a riot.

On my 2.5 van i have a basically stock 2.5t1/mitsu setup with an intercooler and 6* of cam retard on the stock cam, and it still breaks my 25" street tires loose in 2nd when it spikes to 13-15psi so even that level of cam retard isn't killing mid-rpm torque enough to quell wheel spin. It will spin in 3rd on a lumpy road.

So what are you going to do with your carb engine, anyway? I am planning to build a 10:1 2.2/ghead combo myself.. to turbo! With a big cam!

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I've read the negative comments about the G head/2.5 as well, which is why I really hadn't put a lot of thought into using mine.

I'm glad you're kind of confirming my thought process. I was thinking if I run a little larger turbo to keep the boost from coming in so quick it would make it easier to get traction. I have a spare mitsu turbo I could slap on this combo, but I'd be afraid it would spool way to fast, and we all know in the end it would be the limiting power maker...

I haven't really thought about what to do with the 2.2.... It's the original engine. Guess I was just going to wrap it up, and store it for now.

Good luck with your turbo project. I know with the Scamp, I'm running the stock ignition computer, and I only have about 10* initial timing dialed in to keep it out of knock with 93 octane fuel with my 10:1 compression ratio...

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Originally Posted by 83scamp

I've read the negative comments about the G head/2.5 as well, which is why I really hadn't put a lot of thought into using mine.

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Negative? G-head and 2.5 go together like cheese and crackers. Anyone that suggests otherwise might... well... not tried it proper.

Reliant was burning the quarter down with a 2.5 and bathtub head, 'nuff said.

2.5 = longer dwell time at TDC.

Bathtub head = lower pressure spike.

Quote:

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Originally Posted by mopar-tech

Negative? G-head and 2.5 go together like cheese and crackers. Anyone that suggests otherwise might... well... not tried it proper.

Reliant was burning the quarter down with a 2.5 and bathtub head, 'nuff said.

2.5 = longer dwell time at TDC.

Bathtub head = lower pressure spike.

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I'd be interested to hear more about your sucess Gary. Transfering my head to the short block I'm getting would save me some hassle... Can I use the factory 2.5 pistons?

My big concern with using my G head is it's already been shaved .015". I did that & .030" on the block to get the compression up to 10:1... I know the swirl head chambers are smaller, maybe that won't hurt it if I use the stock 2.5 pistons???

Well, first batch of parts has arrived. I scored a like-new 2 piece intake manifold off ebay, for less than 1/2 the going rate, and then turned around and purchased a 10K mile exhaust manifold from the same seller for $22!! The intake was bare, no injectors, fuel rail, or sensors, but I can deal with that. I have a couple sets of TII injectors sitting here, and a 52mm TB from a 3.0.

Next is a trip up North for the short block, wiring harness & SMEC....