building a 2 litre M10 turbo

[e21-Mark]

I'd be inclined to check your info Tommi - these guys have been building and running turbo'd m10's for ages and I'm pretty sure their info is accurate.

[tommi_e21]

ant has been building turbo motors for some time aswell.

im not saying what your saying is wrong, im just not that worried about squish and swirl and all the other stuff.

im not really looking for epic amounts of power so if the car starts to get anywhere near the wrong side of too much boost then i will pull it far back

i have been told a t25 is too small

im just gonna bosh it all together and hope it works.

seems to have done the trick in the past

once i get the 2 litre engine and i start stripping it down and having a proper look i will see how much work is to be done.

[e21-Mark]

I think - from what I have read anyway - that you can get away with a a fair bit when it's just a low boost system so hopefully things will work as you hope. As you say, once you start winding the boost up the other bits and bobs start to need closer tolerances. I'm sure Ant knows his onions too.

My only experience was an old Renault Alpine turbo - Gordini turbo R5 over here - and we just wound the boost up till it went bang. Until that point though, it was all pretty basic ''hit and miss'' stuff that worked well enough although the lag was awful and it torque steered like a Mother Hubbard! In fact it was bloody dangerous and hard to keep in a straight line.

[tommi_e21]

i put a cossie turbo onto my charade and the same sort of result, massive amounts of lag, massive amounts of power and about 10 mins of fun before a big bang occoured.

i have learnt a fair amount of the things not to do when turbo'ing cars so with that knowledge i hope not to make too many mistakes

[jrcook320]

There are always several ways to do something that will work, but there is always a BEST way to do something. The motor will run and the turbo system will work if you go with a thicker head gasket, but it will not run as well or make as much power as if you lowered your compression by machining the pistons. Running a thicker head gasket is the cheap half-assed way to accomplish the goal that is only done for cost reasons. You can run a slightly thicker head gasket without problems, but you will reach a point where it will cause more problems than it will help. The stock head gasket is going to be around .040" thick, I'll hazard a guess and say you could run up to .070" thick. If you go up to .090", that's too much.

This is not merely an opinion on the matter, and squish is not some little detail to be overlooked. It is a fundamental basic requirement for every motor. The more squish you have, the better the combustion chamber you have. Anyone that says otherwise has no clue what they are talking about. At some point, less squish will INCREASE the potential for detonation because of the reduced combusiont efficiency. Avoiding detonation is the whole purpose of lowering your compression ratio. You asked for advice from those that are experienced and I'm trying to give it. I saw you mention running the thickest MLS head gasket you can get and I'm just trying to save you a bunch of heart ache here. It's your choice whether you worry about it or not. Read this thread, learn from others experience:

http://forums.bimmerforums.com/forum/sh ... ?t=1335371

You can bosh it together if you want, but a turbo system is not something to be boshed together. It takes planning and knowledge to match the components of the system so they work well together. I know you're not looking for wild power, my advice applies any way. I have done a significant amount of research on how to calculate air flow to match a turbo to a motor. On a 2.0L m10 with stock head and cam, your volumetric efficiency will be in the 80-84% range at the torque peak. I arrived at this number by modelling the m10 in desktop dyno. From here, I use the ideal gas law to calculate how much airflow a motor will pump based on displacement, VE%, ambient air temp, boost level, inctercooler pressure and temp drop, etc. Once you have mass air flow through the system you can map those numbers on a compressor map. According to my calculations, you will have to run at LEAST 14-15 lbs of boost to reach 250 hp (and this assumes a well designed system: properly sized charge pipes, mandrel bends, port matched everything, good heat control, properly sized intercooler, 2.5" mandrel bend exhaust, etc). This is enough to be pushing the limits of the stock cast pistons, especially if your compression ratio is on the high side with poor squish. If you throw in nitrous you're asking for trouble.

The T25 is on the small side, but it is capable of producing 275-300 hp on a high VE% 4 valve head 2.0L (the SR20DET). On the m10, I know for a fact it can support 250 hp with a very low boost threshold and low lag at it's limit. Larger turbos can and will work well, (gt2860, GT2871, T3 60 trim, even a GT3071 if you're going to run over 20 lbs of boost), just be carefull to not go too big or you will sacrifice low rpm and midrange boost for a high end that you won't be able to use anyway due to your cast pistons.

I recommend you mill the tii pistons to attain an 8.5:1 CR (or at least below 9:1) with a stock thickness head gasket. With the larger combustion chamber it won't take much. If you're set on the nitrous, then I recommend going with forged pistons. If you're going with forged pistons and megasquirt, you might as well just size the turbo to be able to make 300 hp (about 18-20 lbs of boost) on it's own and forgo the nitrous. It won't cost any more at that point. Also remember to file your ring gaps larger than stock for a purpose built power adder motor.

[tommi_e21]

well the plan with all obtained advice and i really do appreciate it i just work on different princepals

ti pistons with the top machined down
mls gasket, standard size
ARP headbolts
t3/4 turbo (will get the specs of the one i have found)
Nitrous (25bhp shot more show than go)
megasquirt control with AEM AFRatio control both ignition and fuel
front mount intercooler sized accordingly
2 1/2 inch mandrel bent system with side exit exahust.
tubular turbo manifold
injectors to suit with custom made fuel rail
century turbo inlet manifold modified for injectors
throttle body is yet to be decided,


another question for the masses

What effect does having the turbo further away from the head, eg longer primarys?
more lag???
thinking a primary place for turbo is the battery tray area as i dont have a battery there any more just a huge amount of space and the inlet for the manifold is relocated to the other side with the century turbo inlet.
i have seen rear turbo kits on cars so its all possible.
would also be different and out of the norm, would save me the pain of having to move the crappy brake brake servo aswell which is my biggest ball ache at the mo

[jrcook320]

That sounds like a pretty good plan.

The 65mm m30 throttle body will fit on the e21 1.8 intake manifold with only minor modification (see my website for more info on that).

I believe the e30 318 intake has a different bolt pattern so the m30 TB won't fit without an adaptor plate (or maybe you could redrill the manifold for new studs?). I think most guys run the e30 325i TB on the 318 intake.

One more thing that just occured to me, the Tii pistons do NOT work with the 1.8L head's combustion chamber. The piano dome is designed for the earlier 2.0L head (IIRC, the 121). With machine work I'm sure you will be able to get them to fit, but it will take careful planning to get the compression ratio you want and also get the shape you need to not hit the head. Just don't go milling off the tops of the pistons blindly.

[340i]

good idea running a 'low power' nos setup, i've heard that it has a chargecooler effect on boosted motors, so with the turbo you'll get more from it than you would n/a, and also run cooler when you hit the go button. plus, you'll be cool like vin diesel...
...just don't run so much nos you blow the welds on the intake....

[tommi_e21]

nos would cool the charge bit only if you spayed it against the intercooler or back far up the system. the extra oygen will only increase temperatures . extra fuel is the only way to cool it down.

im going to be running a century turbo inlet manifold and it comes with it own throttle bodie but i will wait for it to arrive before i decide to change it, i have a wide variety of bits i can steal from fritz so i can try many many throttle bodies to find the biggest within sensible reasons.

not gonna worry about the turbo side of the equation yet, gonna concentrate on getting all the megasquirt fitted. and run it NA on a 2 litre. still got lots of bits to collect from the scrap yard.

[340i]

seems like a lot of hassle, you should just flag it and drop a v8 in

have you got an intercooler yet? are you going hidden or visible front mount?

[tommi_e21]

its going to be behind the grill so pretty much hidden but mounting intercoolers is my favourite job and i dont mind spending lots of time doing it.

dont really want one hanging of the front, too prone to damage really

[Jazziat]

At last,


I found the topic i really want .... and i need a very big help through this topic as i`m really lost in all of that.

I have now an M10 1.8 engine but with the following combaination:

- E-30 M10 head
- E-21 1.8 EY Block (i don`t know for what stands the EY) - this is the original block of my car and the original head was Carb solex 2B4 and i replaced it with a fuel E-30 M10 injection system.

Because my block is damaged currently (the bearings are damaged), so i thought i could change the direction for a turbo M10 application.

i have two options:

1- To buy a used M10 2.0 Block (coming from earlier E-21 engines), and put it on my E-30 M10 head, and then boost the engine with the proper setup.
2- Rebuild the M10 1,8 EY block which i currently have (using the stock component) and install and turbo setup on it.

My questions are as follows:

1- What would be the comprission if i got the M10 2.0L block into my E-30 M10 head
2- Is it a real fact that the internals of the M10 2,0L internals are somehow forged.

3- What is my current comprission now, using the currect setup i have.

Which setup you recomment more, putting in consideration that i have in hand the original block which came with the E-30 head (its also damaged in what regards bearings) and i noticed the huge difference in the piston deck which is very much higher than mine in the EY block.

all i need is a 220 HP from M10 engine with stock internals.


please help.

Thanks
Ragaii

[mr edd]

flat top 2.0ltr pistons were used in euro 320(carb)m10 engines 75/77 and us 320i engines up to 1979....edd...

[Jazziat]

If flat top M10B20 were used in old 320 engine .... then it can easily be fitted to the M10 E-30 head without heating the valves .... i think this is a good start ....

what would be the compression at this stage ??

[tommi_e21]

didnt the old flat tops run 8:1 compression. definatly low enough for boost with a intercooler