M20 and M30 turbo options

[gareth]

as some of you will know, i'm debating the engine to replace my 2.5 M20.

i've ruled out the M series engines in all their multivalve loveliness simply due to cost as and when i break it!

i reckon the M30 3.5 route is the best way forward financially but it does seem that a turbo may be less work. ie, rad, prop, mounts, hoses etc etc all remain unchanged if i keep the M20!

as this has been done a few times on here, what is the realistic cost of a turbo M20 conversion? (assuming no rebuild...). is the 525tds the car to pillage for the manifold?

i know there are some tidy aftermarkket ecu setups but i may be tempted to use an ignition retard module and 7th injector setup simply due to time and money.


oh, and if i did fit a M30, waht manifold would i need and will the turbo fit with the larger lump in there?

i suppose it's all really down to bhp/Ԛ£ at the end of the day but any advise would be great.

[Jos]

Turbo-Brown (bi turbo), Ant and fozzymonster all M20 turbos on the way, on the M30 front, I think the 1st thing you need is a LHD shell tbh... or a bloke that can make manifolds.

[Turbo-Brown]

Well, god knows how much a turbo could be had for as this seems to be completely random!

For the manifold: I had the flanges made up for the head and turbos for about Ԛ£120. The pipe required to make the manifolds was around Ԛ£60 plus a couple of weekends to fabricate them.

Depending on whether you're happy to use the standard exhaust system, you could make a downpipe for less than Ԛ£50 I'd say.

Then there's a scrappy raid for an intercooler and boost piping so perhaps another Ԛ£50 for that lot.

Can tell you're from the 205 crowd Gareth I think you could have real problems with a 7th injector getting fuel to all the cylinders in equal measure.

Not sure how the ignition retard things would work with the standard management but hopefully someone will be along to help out on that one

[gareth]

hehe! spotted! maybe a 7th, 8th, 9th, 10th, 11th and 12th injector then! why mess about!

am i right in thinking standard manifolds can be had from a 324td (M20) and 840i (M30) or am i getting my boxers in a twist?

i reckon the hardest bit to sort will be the exhaust / maifold so if a standard manifold can be souced that'll make life a lot easier!

is the ss scorpion effort i have significanly larger than a standard?

so many questions!

anyway, you got theat bloody GT6 done yet or what?

[Turbo-Brown]

the GT6 is on hold untill the Beemer's done (and to an extent untill miamistu's car's up and running)

Have heard of the TD manifold for the M20, but I thought 840 was a V8?

[Toby_Unna]

u mean 745i (3.5 m30 turbo) i think

but that LHD only.

i wish i'd built mine in a LHD shell why didn't i realise 230lbft wouldn't be nearly enough

[Turbo-Brown]

Can you post a piccy of the drivers side of your engine bay Toby?

Surely there's enough room to get a blower in there!

I mean, if I can get two in.......

[Toby_Unna]

certainly can Alex will get some later.

i think it's possible with custom fabrication of the entire exhaust/manifold. but what got me started was seeing a complete m30 3.5 dinan kit on ebay US that went for about $1500. which would be ideal but was LHD only

[Turbo-Brown]

If you can do the welding yourself, you can make the entire system (inc manifolds) for about Ԛ£450.

Just don't do what I did and try to cut the corner the exhaust follows at the rear or it won't clear the suspension. Must sort that this weekend

[lentec]

them last few corners are tight!

[gareth]

i was kinda close then!!!

i knew it was a M30 3.5 turbo in a 7 series... just a bit vague as to what bmw decided to call it! a 735Ti would make sense!!!

i suppose we're generally screwd by 90% of the world being LHD really. at least the brakes are more out of our way... they could have moved the m/c and servo all over too!

if i do go the turbo route it'll have to be a fairly easy bolt-on bits conversion to get the job done quickly. i have a 3 year old and a <1 year old... half a kitchen... half a bathroom and a bmw widow of a wife to pacify as well!

looks like it's a choice between turbocharging (maybe supercharging but more harware to get done) my 2.5 M20 or swapping in a 3.5 M30... tough call!

i reckon the best way to do the M20 route could be a 2.7 ETA bottom end with a 2.5 head, this is no good for N/A due to the low CR but the forced induction ought to be just the right cure for this! (maths not done yet... could be talking balls!)

at least the main mechanics of the car can remain more or less standard.

[lentec]

i reckon the best way to do the M20 route could be a 2.7 ETA bottom end with a 2.5 head, this is no good for N/A due to the low CR but the forced induction ought to be just the right cure for this! (maths not done yet... could be talking balls!)

That was my thinking on phase 2 i used the m20b27 eta to keep the CR down for the charger and the cam from the 25i mainly for strengh and extra bearings but used the ETA head

It runs a lot better under boost! Or am i just hooked!!

[gareth]

ahh.. what's wrong with the eta cam then? too mild?

[lentec]

For me
And they got 4 extra bearings when fitting dual valve springs the extra strengh must help.

[gareth]

so the eta head casting has the extra bearings but not on the cam? like a large clearance?

seems a bit weird

[lentec]

Well more like the bearings are there but not drilled! look at my site
http://www.lentec.co.uk
I got it wrong first time

Anyway im off to the US to get some bigger injectors

[gareth]

err... looks like that could have cost a bit!!! i assumed that lesson cost the head?