325ix stroker help

[6A LDY]

If you are doing that then I would say put in the cam for sure while you are in there, lighten the flywheel, buy ARP hardware for the head, rods, and mains, Total Seal gapless rings and then talk with VAC or someone about what bearings you should get to deal with turbo abuse. If you do that you'll be in a great shape for the turbo and since you are N/A it will be easier to load the engine and break it in without overloading it with boost so your rings will seal quite nicely.

There are a lot of people making good power on a formula similar to that.

What kind of cam do you recommend, Ive looked around a bit but it seems like a lot of people go with the 272 degree cam?

[77320i]

thanks for the great responses.

I am actually in the middle of doing this myself and the short answer is that it all depends on what you are trying to accomplish.

the goal would be to eventually turbo, but I'd like to have a little fun with the m20 without FI for a little while, but still get prepared for the turbo at the same time if that makes sense

I think I might have similar goals as you, 77320i, in terms of making good power without blowing anything up orhaving to reinforce the front diff too much

Yea that makes a lot of sense and what I was in the middle of until there was an incident where my cat/downpipe section disappeared out of my garage. I couldn't find one online and anyone on R3V or E30Tech said they were willing to ship but then never responded back to me and nobody had anything local.

I looked into the cost of the kit and the price of the manifold and just thought, what the hell. May as well do it now while I can enjoy it and before I get hit by a bus, some moron takes me out, or I become senile and incontinent.

If you are doing that then I would say put in the cam for sure while you are in there, lighten the flywheel, buy ARP hardware for the head, rods, and mains, Total Seal gapless rings and then talk with VAC or someone about what bearings you should get to deal with turbo abuse. If you do that you'll be in a great shape for the turbo and since you are N/A it will be easier to load the engine and break it in without overloading it with boost so your rings will seal quite nicely.

There are a lot of people making good power on a formula similar to that.

[77320i]

quoted because this guy knows whats up. If you're going to the to the trouble to buy $1000 pistons but are worries about spending more money on the crank you have your story backwards.

I paid $300 for my 89.6 crank and you can get that all day long. If you are going to spend over $1k whats another 30%?

Because there was no way I was going to drop $1k on pistons? I agree, if you are going with custom pistons or aftermarket rods and really building something than the 81mm crank doesn't make sense, there are known options that are better and with custom pistons you can get the desired CR for your application.

I however, bought my whole entire SETA bottom end for $80. I think for $80 it's a no brainer to just stroke it and use the 81mm crank then.

[nomansland92]

quoted because this guy knows whats up. If you're going to the to the trouble to buy $1000 pistons but are worries about spending more money on the crank you have your story backwards.

I paid $300 for my 89.6 crank and you can get that all day long. If you are going to spend over $1k whats another 30%?

This is exactly what happened to me. wanted to do a simple freshen up. But whats a set of rings on 250k mile pistons with worn ring lands. And factory BMW pistons are more them custom pistons and then that just unlocks every possibility. So like you said whats a little more for a crank, but I still haven't been able to drawl the line.

[downforce22]

no way would use 81mm crank and custom pistons today, M52 crank as a minimum with a full rebuild IMO, bigger if you want more midrange but arent chasing a high revving engine. it gets uber dollars to make a 3L+ to pull strongly above 6k so its best for a torquey street engine that will make its power at a lower rpm compared to the smaller strokers

quoted because this guy knows whats up. If you're going to the to the trouble to buy $1000 pistons but are worries about spending more money on the crank you have your story backwards.

I paid $300 for my 89.6 crank and you can get that all day long. If you are going to spend over $1k whats another 30%?

[6A LDY]

thanks for the great responses.

[QUOTE=77320i;4212859]I am actually in the middle of doing this myself and the short answer is that it all depends on what you are trying to accomplish.

the goal would be to eventually turbo, but I'd like to have a little fun with the m20 without FI for a little while, but still get prepared for the turbo at the same time if that makes sense

I think I might have similar goals as you, 77320i, in terms of making good power without blowing anything up orhaving to reinforce the front diff too much

[The Dark Side of Will]

For us ix people though the oil dipstick is in a different place, the oil pickup is at the back and not the front, and the intermediate shaft that drives the oil pump is geared different and spins backwards (WTF why? Can someone explain?) so realistically, the best option is to swap in 1988 SETA pistons, rods and the crank.

I'm still baffled that BMW made a different casting for the iX blocks just to put the dipstick in a different place... They couldn't have put BOTH bosses on a common casting and only machined the one that would be used in the final installation? Or machined both and just plugged the one that wasn't used?

Anyway...

The RWD oil pump is in front of the intermediate shaft and driven from behind. The AWD oil pump is behind the intermediate shaft and driven from the front.
Therefore... The intermediate shaft has to spin the opposite direction to drive the pump the correct direction.

The result is that not only do you have to use an AWD BLOCK to build an engine for an iX, but there are AWD-specific internal components that you have to use as well.

ditch the POS "barn door" air flow meter/AFM by switching to an Intake Air Temp/IAT sensor,

The mechanical AFM is junk by modern standards. However, to convert to speed-density, you'll need a MAP (manifold absolute pressure) sensor in addition to the IAT.

[digger]

no way would use 81mm crank and custom pistons today, M52 crank as a minimum with a full rebuild IMO, bigger if you want more midrange but arent chasing a high revving engine. it gets uber dollars to make a 3L+ to pull strongly above 6k so its best for a torquey street engine that will make its power at a lower rpm compared to the smaller strokers

[77320i]

if you're going to rebuild the bottom end, why not get an s52 crank and make a 3L+ stroker?

$$$ and ease. I found a local crank, had a spare set of rods and some pistons and then got a bunk set of local pistons and wound up having to search CL/E30tech/R3V to find enough good ones to use.

The nice thing about going the SETA route is that if you don't need a rebuild then it's a couple seals and some bearings away from being dropped in.

Now.... my S52 M-Tech II vert is totally getting a huge displacement bump before the turbos get added...

[77320i]

Not for you, man. Not for you.

Yea and you're one to talk mister "oh once you sort that out you can come over and turbo my 88 ix"

[downforce22]

if you're going to rebuild the bottom end, why not get an s52 crank and make a 3L+ stroker?

[potshot]

Not for you, man. Not for you.

[77320i]

You can use that 81mm crank your 135mm rods and a set of Ross racing pistons from Ireland engineering and have a good compression 2.8, But it's hard to stop there haha

Does it ever stop?

[77320i]

I am actually in the middle of doing this myself and the short answer is that it all depends on what you are trying to accomplish.

For me, what I've read is right around 450bhp/350AWHP the front diff goes boom so my goal is to be able to get there without pyrotechnics. I decided to use the SETA bottom end. It has the same crank and rods but the pistons are much more like the I motor where as the ETA motor has flat top and not dished pistons. This way the compressions will go from 8.8:1 on the US spec M20B25 to 8.5:1 from the 1988 325e and 528e M20B27 US spec motors. If you use the ETA and not SETA pistons they are different and I'm not sure the exact CR but I believe that it drops it to under 8:1 which means that if you aren't using a turbo it's going to be a bit weak comparatively and if you are using a turbo then you will have less power "off boost" and "under the cam".

Now, if you use the SETA bottom end, this is ideal for two reasons. One, you don't lose that much compression, and 2, it is GREAT for a turbo setup. I'd prefer 9:1 for the turbo but this should give decent power off boost with the higher compression and then be pretty sweet when that PSI starts kicking in and with a tiny drop in CR I should be a bit safer in my desire to avoid detonation. I'm determined to limit it to 350AWHP so I don't blow anything up since it's going to be my winter beater. That might change if I can find a way to strengthen the front diff.

Since you have an M20B25 motor you do NOT need to swap anything. On the ETA motors the intake, exhaust, and cylinder head intake/exhaust runner diameters are smaller and flow less. Additionally they only have single valve springs. On the SETA, while it is an 885 casting the cam profile is different and again, there is only single valve springs. I'm not entirely sure if the intake and exhaust runner diameters are smaller like on the older motors. In addition to that the supporting components changed; the ECU is tuned for an "economy" tune rather than sport and it is also rev limited to less than the I motor due to the single valve springs. The easiest swap for non-ix guys is to just take their I car and swap the bottom short block. For us ix people though the oil dipstick is in a different place, the oil pickup is at the back and not the front, and the intermediate shaft that drives the oil pump is geared different and spins backwards (WTF why? Can someone explain?) so realistically, the best option is to swap in 1988 SETA pistons, rods and the crank.

I would definitely recommend a cam either for N/A or split turbo one depending on your future mods/desires and a either a chip with a tune, or better a Miller W.A.R. chip or even better yet MegaSquirt.

With the MegaSquirt unit you have a LOT of flexibility and can do things like ditch the single ignition coil and go to a wasted spark setup using GM 3800 Series II coil packs for a more powerful spark and ease of turbo, use semi-sequential fuel injection instead of batch, add a GM/Ford FlexFuel sensor to run E85 which allow more timing and flexibility in fuels for street or track, add dual knock sensors from more modern BMWs, ditch the POS "barn door" air flow meter/AFM by switching to an Intake Air Temp/IAT sensor, allow multiple tunes, sensor feedback, timing advance and retard based on demand and load, and about a million other reasons. Yes, the tuning sucks but hey, you add options and complexity and you add time and difficulty.

I'm personally doing most of that on my 1989 325ix and I bought the KA Motors M20 turbo kit for a base but used the cheap a$$ china CXRacing manifold because it seems to be the only one to clear the front axle and strut towers on the ix at this time and also the CXRacing turbo back exhaust because $750 for a stainless turbo back seemed like a deal and I'm not confident enough in my welding abilities yet. Plus if you remove the stupid "plug" in the muffler for "sound dampening" then it's a full true 3" turbo back.

My .02 is go for it but buy some SETA pistons and enjoy the added power, mean sound, and additional fun right now and when you have time, hit the turbo button.

[nando]

yeah you can swap the bottom end into an ix block but it wouldn't be worth doing using eta pistons.