Turboing BMW M40 engine?

"davedave1111" (davedave1111) 01/15/2015 at 06:48 • Filed to: None

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So, I'm not really seriously thinking about this (yet), but I noticed that it makes almost no difference to my insurance if I turbo the 318, and I have to fix the manifold studs anyway so it's not like it would be a huge amount of work to add a turbo while I'm there.

I can't find a turbo kit for the M40B18 engine, though. Does anyone know if it's a workable plan? If so, roughly how much would it cost to do it on the cheap? Is it going to kill the engine if I just give it a mild boost?

From what I can see on Google, I'd need a custom manifold to fit whatever turbo I got (unless an M42 manifold will fit), but other than that, could I do it with cheap junkyard parts? With the number of diesels about, I ought to be able to find any number of low-mileage turbos of all sizes for not too much.

If I'm just going for low boost pressure, do I need an intercooler? What else should I be thinking about?

pip bip - choose Corrour > davedave1111 01/15/2015 at 06:50

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sounds like a reasonable plan , good luck.

davedave1111 > pip bip - choose Corrour 01/15/2015 at 06:53

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Thanks, but I was hoping for a bit more in the way of advice, because I have no idea what I'm doing :)

Do you know how much more to a basic setup there will be than just plumbing in a small turbo?

Cé hé sin > davedave1111 01/15/2015 at 07:01

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It's not that simple. When a car maker produces a turbo model they don't just bolt on a turbo. For a start the compression ratio is lowered and the engine is modified in other ways as well. Don't just bash away and hope it all works.

davedave1111 > Cé hé sin 01/15/2015 at 07:07

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I'm sure it's not that simple, although the internet says the engine can handle a little bit of boost with no trouble, and the internet is always right...

I have no idea at all what the other modifications needed to make it work would be. That's what I'm asking about. From what I understood from google, the engine as it stands can make use of the boost without internal modifications, but I assume it'll need things like the fuel pressure boosting too, and that kind of thing. For all I know, though, those things are enough over spec on the engine to handle it stock.

pip bip - choose Corrour > davedave1111 01/15/2015 at 07:08

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not being into BMW's or a tech , i'm clueless , sorry!

pip bip - choose Corrour > Cé hé sin 01/15/2015 at 07:11

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where's the fun in that.

what's the worst that can happen? engine detonates?

at least there's a good chance of some broken engine pics.

and some of us here will have a good laugh at someone's expense. LOL :)

imadeaburner > davedave1111 01/15/2015 at 07:14

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You need a new oil pan, new manifold, the turbo, a wastegate, turbo piping, an intercooler, a tune, down pipe, blow off valve or a diverter valve fuel injectors possibly different plugs if they are a high heat range.....

ITs more than just slapping a turbo to it and hoping for the best.

First off, getting the manifold, you are going to want to just get a good manifold, doubtful that the diesel one will work. It may be too heavy and pull studs out or just work the head sitting there. So get a custom one aftermarket.

Then the turbo, you want low boost, so get a small trim turbo, depending on the flange for the manifold will dictate what turbo you get and trim sizes and whatever else.

The Oil pain is needed so you can do the oil feed and return, you could just drill into the pan and hope it works, but that needs to be figured out.

Wastegate, tuirbo piping, and the blow off or diverter are all necessities. Can't really get around them.

The intercooler I would recomend, cause maybe down the road you want more boost, or a bigger turbo, and its nice to have cool air going into an engine.

Injectors and plugs, things people over look when doing a turbo, add more air you need more fuel, if the plugs are too hot then it can preignite or burn everything too quickly.

The tune, you can't slap the turbo on without telling the car what to do when it sees atmosphere + 7 pounds or so,

Turbos are a lot of work, you are best off staying NA and leaving the car as is, if you are motivated and want to slap the turbo there, and have the money and the technical ability, go for it.

Drakkon- Most Glorious and Upright Person of Genius > davedave1111 01/15/2015 at 07:24

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Back in the 80s, if the OEs were looking to add a turbo at 6-9 psi, they skipped the intercooler.

If I remember correctly, Saleen used a very low psi turbo setup on the S7 and they did not include an intercooler either. So here is your inspiration.

As far as the monifold goes, yes, it sounds like you need a custom. A tubular manifold will be much more expensive and in the long term, also more likely to crack due to heat expansion and cooling contraction. You need a really good welder (ain't me!) to do this right. Anyone will tell you 'sure I can do that' but trust almost none of them.

A 'log' style manifold will not yield you all the fancy schmancy effects of a tubular manifold, but it's less likely to crack and will be much cheaper. Likely last longer, too.

Whichever manifold style you choose, even though it looks gross, get the heat wrap tape and do a very clean and thorough job of wrapping the manifold right down to the flange. This will help keep the heat in the manifold and out of your engine bay, it will also keep the intake pipe which may or may not have an intercooler cooler and it will help minimize expansion/contraction.

If you don't like the looks of the heat wrap, make a nice aluminum heatsheild to hide that whole side of the engine.

Most importantly, you need a method of feeding the engine more fuel to burn the extra oxygen your turbo is providing. Running lean is the death of most home-built turbo setups. I know jack-squat about BWM fuel injection so you'll have to look for help from someone else for that. I know a lot of 90s Japanese engines will 'error' when the manifold sensors see more oxygen in the intake than the atmosphere can hold. GM engines of the same era don't have the trouble. Do a most of your research here.

Good luck.

Sam > davedave1111 01/15/2015 at 07:56

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Can you weld? Because you'll need to make a custom manifold. Though really, if you can we making a manifold isn't hard.

AM3R shamefully returns > davedave1111 01/15/2015 at 07:57

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pretty good thread.

http://www.e30tech.com/forum/showthre…

Jobjoris > davedave1111 01/15/2015 at 08:20

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Good luck with that. But let me prevent you from nightmares, empty wallet, non-decent-running engine, divorce and all probable negative emotions in life: get an M20B25 instead.

Much easier. Won't cost you that much (in the end).

GhostZ > davedave1111 01/15/2015 at 08:26

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For the cost, an engine swap is probably cheaper. But if your insurance would explode otherwise, here's somethings to consider:

1. Cooling. You will probably need a larger radiator. This is probably the single biggest thing when it come to modification that is overlooked.

2. Exhaust. You'll need to adjust the exhaust manifold (maybe do some custom work) too to fit the turbo. This includes wastegate, downpipe, etc.

3. Drivetrain. Is the extra torque/HP going to be straining the transmission, differential, axles, etc?

4. Compression. You'll need to avoid predetonation. The stock motor might be able to handle 'a little' boost, but 3-6 lbs of boost (0.2 - 0.4 bar) is only going to net you ~20 - 30 HP on that motor, and drastically reduce it's life, at least from what I know. You may see less, if the turbo's peak delivery isn't at the same time as the cam, and if it is, there's going to be lots of lag. This is what happens with junkyard turbos: high torque, lower lag, high HP, tons of lag.

5. Fuel. If your fuel pump and lines aren't delivering enough fuel, you'll run lean and overheat.

6. Brakes. If you're going to be turning this into a 160-200HP turbo monster, you will need better brakes or you'll end up killing yourself on a backroad.

GhostZ > pip bip - choose Corrour 01/15/2015 at 08:27

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Given that he's concerned with the cost of insurance, I'd say that risking an engine blowup is just not in the cards for this guy.

davedave1111 > GhostZ 01/15/2015 at 08:36

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Er, I said I'm not worried about the cost of insurance here. I'm just spitballing because I happened to notice that my insurance quote only goes up by £35 or so if I tick the 'Modified - turbo' box, where I expected it to be a couple of grand.

Given that I paid <£300 for the car in the first place, I wouldn't be devastated if it blew up - but I wouldn't want to take any risk. The internet says it can handle quite a bit of extra power without causing problems, if it's set up right.

davedave1111 > Drakkon- Most Glorious and Upright Person of Genius 01/15/2015 at 08:40

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"Most importantly, you need a method of feeding the engine more fuel to burn the extra oxygen your turbo is providing."

Yeah, I was thinking that. Apparently higher-flow injectors from the M50 engine will fit just fine, so that's not too big a problem. I have no idea if the ECU can handle mild boost as stock, simply adjusting the fuel flow for the increased air-mass reading. I'd guess not, though.

As for the manifold, is it possible just to add some sort of piece between the manifold and the downpipe? Seems like it would be much easier to fab.

davedave1111 > imadeaburner 01/15/2015 at 08:45

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"ITs more than just slapping a turbo to it and hoping for the best."

I'm sure :)

I guess what I'm asking is what the most minimal setup could be, given that I'd be happy with only a little bit of boost.

"Wastegate, turbo piping, and the blow off or diverter are all necessities. Can't really get around them."

Do turbos with built-in BOVs and wastegates exist?

"The tune, you can't slap the turbo on without telling the car what to do when it sees atmosphere + 7 pounds or so,"

I was thinking more like 3-5 psi, but yes. Just changing the ECU and having it flashed isn't a lot of labour, though.

"Turbos are a lot of work, you are best off staying NA and leaving the car as is, if you are motivated and want to slap the turbo there, and have the money and the technical ability, go for it."

I doubt I'll ever actually do it, but it would be fun. I just don't know anything much about turbos beyond the basic principles at work.

davedave1111 > GhostZ 01/15/2015 at 08:52

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"For the cost, an engine swap is probably cheaper."

It's probably cheapest just to sell the car and buy something quicker, but where's the fun in that?

The funny part is that I expect I can get a turbo for very little money, but seemingly littler things like plumbing it in would require custom work and cost much more.

1. I think it's the same radiator as on the bigger-engined models, so ought to be OK.

3. I think that's all fine as well, for much the same reason. I wasn't thinking of a huge increase in power.

4. According to the internet, the engine ought to be fine with a small power increase, without killing it quickly. I was thinking about 20-30bhp would be nice, but that was assuming it didn't cause any longevity issues. More torque low down to help spin the wheels would be great :)

5. Yeah, I was wondering about that. Again, though, I think it's the same fuel pump for all the engines, so it should be fine. Might need higher-flow injectors, but they're a straight swap.

6. Now where's the fun in that?

davedave1111 > Jobjoris 01/15/2015 at 08:54

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Is it really easier? I always figured an engine swap would be a lot of work. If you have all the tools and parts, plumbing in a turbo looks like a relatively small amount of labour.

If I was going to do an engine swap, anyway, it'd be for something completely non-standard. Otherwise it'd be much simpler just to sell my car and buy another with the engine I want.

davedave1111 > Sam 01/15/2015 at 08:55

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I can't, although I keep meaning to get the kit and learn. But I was assuming I'd have to get someone else to do it.

davedave1111 > AM3R shamefully returns 01/15/2015 at 08:59

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Yeah, that one turned up when I was looking for a turbo kit on google. Unfortunately it doesn't get specific about anything much. I'd love to see what his manifold looks like.

Drakkon- Most Glorious and Upright Person of Genius > davedave1111 01/15/2015 at 09:17

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This is where finding a mentor who has done it before would be the best.

Like I was saying, a japanese engine (most of them) with a hot-wire Mass Air Flow sensor would freak out.

A GM air-speed-density sensor would be none the wiser and this would be gravy. It just depends on air measuring system. But some guidance from someone who has done this before would be the best.

Also, your idea of just a short pipe to change from the current manifold to the turbo flange probably is your best bet. Just keep it as short as possible.

Sam > davedave1111 01/15/2015 at 09:22

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Yeah, you can probably find a shop to do it fairly easily. Just don't get an eBay manifold, if there are any, they're bad news.

Jobjoris > davedave1111 01/15/2015 at 10:19

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If I'd mount a Turbo that engine was gonna come out anyway I suppose. Think about all the pipes you'll need to 'plumb': the exhaust manifold (after all, just an arrangement of plumbing that connects the exhaust ports to the turbine), the inlet from the airfilter, the outlet to the intercooler (if used), the exhaust pipe out of the turbine, cooling water in and water out, the oil pressure feed and oil drain. Doing all that with the enige in is probably possible but then again: Getting that engine out and another one in probably takes you far less time. And a Turbo'd engine would really benefit from lower compression and other ignition/fuel settings.

Mounting that M20B25 is considered the easiest swap because all the parts are standard BMW. There's no need for custom components, and everything you need can be supplied by one donor vehicle. There is no fabrication or welding required, and just a few brackets need to bolted on under the bonnet for engine ancillaries.

You can always buy another car, but that's the easy way out!

imadeaburner > davedave1111 01/15/2015 at 17:13

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You can get them with the Diverter valve and a wastegate built in, they are entirely unreliable long term from the aftermarket that way though

The tune is hard, I do my own tuning and it takes weeks to get them set sometimes

3-5psi is not nothing, I would still do an intercooler with even a little boost, without one your temps on intake will be notably higher and on a hot day you will have nightmares.

Even the most minimal setup is going to be costly.

davedave1111 > imadeaburner 01/18/2015 at 05:16

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"You can get them with the Diverter valve and a wastegate built in, they are entirely unreliable long term from the aftermarket that way though"

Oh? I thought it was a normal thing these days, with stuff like Garrett turbos?

"The tune is hard, I do my own tuning and it takes weeks to get them set sometimes"

That's one bit I really don't understand. I know the theory, again, but I have no idea how you actually go about setting up an ECU. Why is it hard? In theory(!) you just calculate the fuel and airflow throughout the rev range, don't you?

"Even the most minimal setup is going to be costly."

As I said, there are endless cheap turbos available. It's all the other bits and pieces which would be expensive...

davedave1111 > Jobjoris 01/18/2015 at 05:26

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If the engine was coming out anyway, then you'd have a point. But that's to be avoided. And TBH the good bits of the car are the engine and transmission, so doing a swap would be completely daft.

It doesn't seem to me that the plumbing would be too hard to sort out, if there's space for the exhaust bits. The hot-air side is dead easy on that engine.

I'm surprised you think a swap would take less time - I'd expect a swap to be loads of work.

Jobjoris > davedave1111 01/18/2015 at 12:29

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And TBH the good bits of the car are the engine and transmission, so doing a swap would be completely daft.

If the engine is the only good bit (you could even leave that transmission in place if I remember correct): Why mess it up? Don't get me wrong, I get this point but again: It's not just adding a different exhaust/manifold/turbo to make it a usable engine. That M20B25 is usable instantly.

Swapping an engine isn't that hard. If you take one day to get the old one out and another day to put the other one in: fairly possible (not considering changing the struts, brakes, etc). This is a well documented swap, as OPPOsed to your M40-turbo project. For a reason.

But I'm always in f0r a good documented project: so please make this dream happen and keep us posted!

davedave1111 > Jobjoris 01/18/2015 at 15:03

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"but again: It's not just adding a different exhaust/manifold/turbo to make it a usable engine."

Yeah, that's the kicker really. As it is, I won't do anything, in all probability. It would be better to put the effort into getting the car nice, then sell it and buy something else. Or just to get it on the road again :)

Really, it was more of a matter of interest than any serious plan. A 'why not', not a 'how'. You have to pull the suspension to get to the exhaust manifold on an RHD E30, and I have to do that anyway, so I wondered how much extra effort it would be to slap a minimal turbo setup on while I'm there.

What I have so far is custom manifold; LPT; oil feed and return; plumbing to the intake; bigger injectors; ecu rejigging of some kind.

imadeaburner > davedave1111 01/19/2015 at 06:19

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THe diverter valve and wastegate being included isn't always normal, on a factory car turbo yes, anything aftermarket isn't going to coem that way usually.

Any turbos I have been looking at have had the diverter and wastegate seperate.

And its not just calculating air flow and air fuel ratios. Spark timing, VVT Timing if that is a Vanoss engine.

And if you go cheap on a turbo don't expect it to last even at low boost, I've seen Ebay turbos do great, but then I've seen them fail at a low boost setting like you want, even in low boost conditions the compressor and impeller wheel will be spinning at high RPM and any unbalance can cause a catastrophic failuere/