1.3 Motronic Up-Grade & 2.7i How To

[ForcedFirebird]

I'm doing a head swap along with the motor if upgrade and the head will come off with both manifolds attached.

Do I assume correctly that that's the ideal point to swap harnesses ?

A harness swap isn't too bad by itself, really. The A/C bracket needs to come off if you don't want to cut the oil pressure sensor wire, and the OEM CPS wire routing is kinda a pain unless you remove the water pump pulley at minimum (in the "i" setup).


Generally when we pull an engine at the shop, the ECU connector comes out of the firewall, the oil pan ground leaves the frame-rail, the C101 gets disconnected, and it all come as a unit.

[jeffnhiscars]

I'm doing a head swap along with the motor if upgrade and the head will come off with both manifolds attached.

Do I assume correctly that that's the ideal point to swap harnesses ?

[ForcedFirebird]

All the "I" stuff is the nearly plug and play from 87 up in US spec. Some chassis differences, like the pesky #20 on the c101 and water pump etc. The earlier "I" had motronic 1.1 153 variant ecu, but it all bolts and plugs together. Keep in mind the AFM needs to match the ecu, along with injectors.

[ATL_E30]

I'm BACK!

Best bet is to just put the whole b25 in your eta. The "stroker" using a flat piston piston engine with 885 head doesn't make as much power as a plain b25.

So I sold the car with the b25 so i'm back to looking into building a stroker... One thing that still wasnt answered from my original post. Can I take parts from a pre-88 (IE. i intake, ecu, etc.) or do I need to stick to these parts from an 88+?

[ForcedFirebird]

I've got an 84 325 and I'm in the process of gathering parts. Are the pulleys really needed? Why?

The crank pulley has the crank sensor on it for the M1.3, your eta has a smooth crank pulley and the crank sensors in the trans bell housing.

The water pump pulley doesn't "need" to change, but it will turn slower when using the "i" crank pulley and eta water pump pulley, and you will need to use a non-stock belt.

If you go on realoem.com and poke around at the eta and "i" diagrams, you will see the differences.

[thejimlab]

Are the pulleys necessary?

I've got an 84 325 and I'm in the process of gathering parts. Are the pulleys really needed? Why?

[ForcedFirebird]

"For the 1988 model year, the eta cars got a refresh from the factory. This included a newer Bosch Motronic version with adaptive idle control, a 325i head casting with the larger valves, ports, revised combustion chambers and water jacket, new pistons to fit the 2.7 L stroke with the 2.5 L head, a dual exhaust system and a 5300 RPM rev limit. Though it only made slightly more power in stock form, it could be easily boosted by bolting on a 325i head, a complete 325i intake manifold and throttle and plugging in the 325i engine control unit. Depending on which cam, chip and intake is used, the combination can make over 180 horsepower with the stock compression ratio."

Why bolt on the 325i head onto a SETA block if the two are the same? What, if any, are the differences? It makes sense that Kenika65 says to do this swap with the SETA you only need the intake manifold, TB, and ECU, but later says bolt on the i head to boost it? Why bother?

And ForceFirebird, do you have a picture depicting which pin on the C101 is the #20? I guess I got plain lucky I didn't fry mine when plugging it up. I do have an issue overall with my setup, the engine revs will fluctuate when warmed up and the gas pedal is down, suddenly cutting out and recovering. Haven't identified the problem yet, wondering if it doesn't have something to do with my wiring. If I can't figure it out soon I'll have to take it to the local indy.

The head castings are the same. The 88 eta got single valve springs and a 7 bearing eta camshaft. It also got a seta-specific intake manifold that has the skinny runners and TB like the eta, but the ports open up right at the head.

I don't have a pic handy, but if you peel back the rubber boot the numbers are next to the pins (also on the face side when unplugged).

What AFM did you use? The eta AFM doesn't work properly with the 325i electronics.

[MrWolf]

ForcedFirebird, whoops, don't know where I got "883". Apologies for any added confusion. You certainly spelled out your credentials - I've got one project still in progress under my belt, undoubtedly I am the amateur here.

I obviously was confused, so help me understand here. Back from page 1:

"For the 1988 model year, the eta cars got a refresh from the factory. This included a newer Bosch Motronic version with adaptive idle control, a 325i head casting with the larger valves, ports, revised combustion chambers and water jacket, new pistons to fit the 2.7 L stroke with the 2.5 L head, a dual exhaust system and a 5300 RPM rev limit. Though it only made slightly more power in stock form, it could be easily boosted by bolting on a 325i head, a complete 325i intake manifold and throttle and plugging in the 325i engine control unit. Depending on which cam, chip and intake is used, the combination can make over 180 horsepower with the stock compression ratio."

Why bolt on the 325i head onto a SETA block if the two are the same? What, if any, are the differences? It makes sense that Kenika65 says to do this swap with the SETA you only need the intake manifold, TB, and ECU, but later says bolt on the i head to boost it? Why bother?

And ForceFirebird, do you have a picture depicting which pin on the C101 is the #20? I guess I got plain lucky I didn't fry mine when plugging it up. I do have an issue overall with my setup, the engine revs will fluctuate when warmed up and the gas pedal is down, suddenly cutting out and recovering. Haven't identified the problem yet, wondering if it doesn't have something to do with my wiring. If I can't figure it out soon I'll have to take it to the local indy.

[ForcedFirebird]

I appreciate everyone's input here! Very knowledgeable all around! My main question though however was should I be sourcing all of these parts from any e30 or should I be focusing mostly from 88+ e30's.

Reason I ask is because I have an 87 iS as well and if i'm unable to sell it in a timely manner I would look at parting it out and keeping all the i bits needed for this conversion.

Thanks!

Best bet is to just put the whole b25 in your eta. The "stroker" using a flat piston piston engine with 885 head doesn't make as much power as a plain b25.

[ATL_E30]

I appreciate everyone's input here! Very knowledgeable all around! My main question though however was should I be sourcing all of these parts from any e30 or should I be focusing mostly from 88+ e30's.

Reason I ask is because I have an 87 iS as well and if i'm unable to sell it in a timely manner I would look at parting it out and keeping all the i bits needed for this conversion.

Thanks!

[ForcedFirebird]

The SETA also used the 200 cast cylinder head - you will want to replace with an 883 "i" cylinder head to make the most of the conversion. The 883 uses bigger intake valves, has larger intake and exhaust ports so it "breathes" better and is where you are going to make the most difference.

The SETA uses the same pistons as the i, but with a longer stroke so the 88 is actually the ideal car to use in this "stroker" build. Replace cylinder head with i head and components, and use an i ECU and wiring harness and BAM! - you've converted your ETA into a stroked 2.7i

All this is pretty well documented throughout the 50+ pages of this thread and on other threads of r3v.

You are confused, it's right on page 1!!! Please fact check before challenging a senior member and/or giving advice to other members.

1988 super eta, seta

Parts Needed:
i intake manifold, i 173ecu(computer in glove box)

Optional Parts:
i cam, i double valve springs, i duel exhaust, i radiator and expansion tank, i single fuel pump fuel tank and fuel lines, i flywheel, i transmission with drive-shaft(Must use original center support bearing), i differential(4.10 from ix), i brake booster, i 90amp alternator[U]

I will take the "883" as a typo. The seta does NOT use the same pistons as the "i", as the rod pin was moved to account for the 130mm rods and 81mm stroke (top domes are the same shape, though). If you put seta pistons in an "i" motor, they will stick out of the block ~2mm. Likewise, if you put "I"pistons in a motor with 130mm rods and 81mm crank, the pistons will be 2mm down in the block. I shave blocks 2mm to do this combination often and it results in a 9.5:1 2.7 with all the good things an m20 has to offer. The domed shape pistons in the "i"/seta do not interchange with the 200 head as the eta pistons are flat to match the 200 head flat combustion chamber.


The 1988 seta came with an 885 head, eta 7 bearing cam (200 head has 4 cam bearings), seta-specific manifold, eta TB and seta-specific ecu. Right now in my workshop I have TWO seta engines, 28 m20 cylinder heads in various stages of rebuild, and 8 m20 rotating assemblies in various stages of rebuild. I have owned 14 e30's and opened my shop in 2009 which has about 90% e30 clientele.


Even flowed the 885 head with a seta and stock manifolds on my flow bench. I have dyno tested countless options (my dyno files are in the thousands). Your eta with 885 head will make around 135whp as it sits. A stock tired b25 makes about 150. The seta with an i cam/spring/electronics are in the 165 range. The b27 crank with eta rods/crank and block shaved 2mm makes about 175. Change the crank to an 84mm, they go over 180.

Also to anyone following on my previous post regarding the C101 connector - the issue with the mismatched number of pins was not an issue for me. I got my car running with no alterations or hacking of the wiring harness. An 86 eta and a 89 i harness WILL work!

I did my first eta top end swap over a decade ago on my first e30 (about the time this thread was started), and have done numerous since. There's only one wire you need to worry about in the c101 and that's #20. #20 on some cars are a power, some are ground and some are empty pending production date. Later models have a red/yellow wire, some early brown, some early empty. If you plug a red wire into a brown wire, you will fry the body harness under the steering wheel (ABS relay circuit), and your engine harness will be toast. I have seen people do it so many times, and repaired burnt wiring I don't know how many times.

[MrWolf]

Also to anyone following on my previous post regarding the C101 connector - the issue with the mismatched number of pins was not an issue for me. I got my car running with no alterations or hacking of the wiring harness. An 86 eta and a 89 i harness WILL work!

[MrWolf]

All you need to change is the valve springs, cam, ecu, inlet manifold and throttle body when you have an 88 "seta"

The SETA also used the 200 cast cylinder head - you will want to replace with an 883 "i" cylinder head to make the most of the conversion. The 883 uses bigger intake valves, has larger intake and exhaust ports so it "breathes" better and is where you are going to make the most difference.

The SETA uses the same pistons as the i, but with a longer stroke so the 88 is actually the ideal car to use in this "stroker" build. Replace cylinder head with i head and components, and use an i ECU and wiring harness and BAM! - you've converted your ETA into a stroked 2.7i

All this is pretty well documented throughout the 50+ pages of this thread and on other threads of r3v.

[ForcedFirebird]

Also, here is a great site for information on swapping your eta to later model equipment...

http://strictlyeta.net/technical/328i_1.html

[ForcedFirebird]

In the very early stages of collecting parts for this. I have a stock 88 325 super eta, so my question is do I need to collect parts for 88+ or can I get an i manifold, ecu, etc from a pre 88?

Thanks in advance!

All you need to change is the valve springs, cam, ecu, inlet manifold and throttle body when you have an 88 "seta"