325... which path to take

[will_c]

Hi there, Im currently umming and arghing about selling up my 200sx S14a and getting a E30 325i. Now a standard 325 is no where near fast enough for my boost adiction so i would be buying one as a project. Due to the mileage found on these engines a rebuild would be called for and it would make sence to build a nice low compression forged engine to accept a turbocharger. I would be looking for around 350 - 400 bhp with a Garret GT ball bearing turbo and a stand alone engine management system. The only thing i dont really know about is the bottom ends found in these cars. Which is the best one to turbocharge, obviusly i ll be going for low compression forged pistons and rods, and a thicker head gasket but are there any issues i should consider on the 325i engine regarding my plans?
Are there any bmw tuning companys/engine builders i could discus this with?

Cheers

[Turbo-Brown]

Go for the low compression later engine and you shouldn't have any probs getting to your target 350bhp

If it goes pop, buy another one for a couple of hundred quid and off you go again!

Little bit bizarre that you'd elect to use low compression pistions AND a thicker head gasket though, one's the correct way to lower compression, the other's not, and if you're using one, why bother at all with the other?

[will_c]

well i want a fully rebuilt and forged engine so does it really matter which engine i get?
i.e, are there any issues with taking an engine from an F reg 325 and sticking forgies in and a thicker head gasket? obviusly the compression ratio will all have to be calculated and the block will need machining etc.

[Turbo-Brown]

Guess not in that case, but why on earth would the block need machining?!

And why would you want to weaken your strong new engine with a thick head gasket?!

[will_c]

you ll have to forgive me, i dont really know anything about these engines yet. The block will need the general machining work for the rebuild i.e honing the cylinders or boring them out if i went for larger capacity etc. Thicker head gasket to aid the lowering of the compression ratio but if its low enough already? then it wouldnt be needed.
How much can you safely increase the capacity?
what sort of compression ratio should i be aiming for?

[maxfield]

I don't think you can bore it out anymore. but you can stroke it to 2.7 or 2.8.

The later engines are only a compression ration of 8:5 or something cloe to that. Which is low enough to run high boost.

[Turbo-Brown]

I know Player6 has a 2.8 which is using the crank from some E36 engine or other and presumably an overbore.

You could probably start off with a 2.7 (there seem to be various ways of going about that one).

The stock compression on the later engines is less than 9:1 anyway (8.8:1 springs to mind but someone will be able to say yay or nay to that one) so they can handle pretty large doses of boost

I'd say if you're going to the trouble of getting forgies, get them made up so that you don't need the thick HG. It's such a bodgetastic way of compression lowering!

Sounds like you've got some cash to put into this engine if you're talking about forged pistons and steel rods, would be a shame to build in a weak link

[will_c]

really? hmm thats pretty blooming cool then!
so i could just get a later engine, stick some forged pistons in and bolt on a turbo!
mmm

[maxfield]

I think ant said 8:8:1 at aces iirc

[maxfield]

TBH you could just stick on a turbo without forged pistons and run to a certain amount of boost

[will_c]

well what it is is im going to sell my 200sx and buy a car for around 3k with a mint shell and a suitable suspension etc, that leaves me with 3-4 grand to play with the engine. £1000 of that will be the turbo and id want a rebuild gearbox aswell.
How much power and torque can a standard box take?

[Andy335Touring]

Like Alex said, if you are going to build an engine with low comp pistons you don't need or want a thick gasket because this increases your squish height which isn't ideal, have a read of this and good luck with your project as it sounds cool

This was posted for me on another forum




This is where this info was taken from, it might be a good referance book to have for your project ?

[Lee_Coupe]

Will_C...

Dont suppose you used to have a Rover Turbo in black with 18/19's? used to be on rovertech, I used to own a coupe! (Lee_Coupe)

You've joined the bimmer world aswell I see

[will_c]

I did mate!

http://img175.echo.cx/img175/7167/1111157img9aq.jpg

i broke it in the end and got about 9k for it in bits! Some fella in spain bought the engine and box for about double their value lol
bought a 200sx but my new job means too much traveling to have a car like that!
need a crappy van or somthing and then i ll have £Â£Ã‚£ for project bmw

[Lee_Coupe]

I remember mate, That thing was fcuking lovely!

Sadly there not RWD tho lol

Sold mine for a nice profit to pay off some depts and buy my touring.

Good luck with the new project buddy, going by the standard of your rover Im sure the BM will be a lovely car!

[Boots_Walker]

given your target of 350-400hp i would be inclined to start with a 8.8:1 2.5 and leave the bottom end stock, m20's are tough and i believe that those power levels are safe provided the car is setup and tuned properly.

thats my opinion

[E30BeemerLad]

I don't know much about your existing car, but is if the car ain't too smart but the engine is healthy and not suffering with the usual main & big end knock, then why not transplant it into the E30?

When I have the cash & facilities, I'm gonna do a jap transplant into an E30, using the 7m GTE lump out of a UK MK3 Supra, or if I am lucky enough, the 1-jz out of a TT Soarer/ MK3 Supra import.

[Jhonno]

if your gonna run custom pistons then you can dictate CR, could stroke it and bore it out slightly (i believe they will take a small increase in bore size

350-400bhp is achievable tho, maybe even on the standard bottom end if you do it properly 270bhp is the highest turbo'd figure i can remember from here on a standard bottom end

[Turbo-Brown]

270bhp is what I'm getting, and that's only on 7psi with the high CR engine.

Sure Ant and Fozzy are getting way more than that, think Fozzy's running 20psi or something crazy like that on a standard low CR engine!

[e30_Turbo]

I've peaked at 1.3bar but that was too much for the head bolts and it slammed no 1 and 6 HG clean into the water channels.

Next time it goes it'll go big time, then I'll buy another one and strap the bitch on again!!

LOL @ £1k Garret tho....... you guys are all nuts

[Jhonno]

Turbo-Brown.. yours is the only one that been r/r so far tho..

[Ant]

yours is the only one that been r/r so far tho..

wanna bet M8

[Jhonno]

lol

meant to say only one thats been r/r and figures shared that im aware of...

share the weath then dude..

[WillG]

I don't think you can bore it out anymore. but you can stroke it to 2.7 or 2.8.

The later engines are only a compression ration of 8:5 or something cloe to that. Which is low enough to run high boost.

you can bore it out to 85mm fine

Will C, if you want forged pistons (which you dont need) then contact JE and tell them was CR you want and fit a stock thickness MLS headgasket or get block o-ringed when you have it bored , fit new bottom end bearings, rods are fine as they are but if you go to 500hp swap to M50 rods.

Or you could just do new rings, bottom end bearings and get a .140" MLS gasket to low CR abit, or you can mill/lathe pistons abit aswell.

Dont need forged rods atall, might want to get a balance with forged pistons cos they abit lighter but people have fitted them and done ok without

[d6dph]

lol

meant to say only one thats been r/r and figures shared that im aware of...

share the weath then dude..

Hehe i know! well i was at one of the r/r runs. not sure if its been done again.

but my lips are sealed

[will_c]

Whats involved with increasing the stroke then?

Well i ve been thinking about some of the things im gonna want to do.

over bore, increased stroke, JE custom forged pistons, fully balenced bottom end, metal head gasket and an ARP head stud kit

will the standard head be ok to use for a while? i.e valve sizes, cam profiles etc?

[WillG]

I wouldnt bother stroking it if you turboing its more hassle then its worth,

Rest of its fine, could throw a custom cam in there aswell for £200 but its not needed.

Whats your budget and what engine management and exhaust manifold are you going to use. I would seriously consider just rebuilding bottom end stock, put a thicker MLS in, Get head welded and a custom cam and put a holset on and your gona save alot of money and get same or better result then what you just mentioned result if your on any sort of budget that is by far best value for money.

Some guy ran a stock bottom end but totaly rebuilt along with head which was welded, 372 PPF cam, oringed block, stock 8.8:1 compression and was using a autronic ECU and he made 600hp and that was reliable he went up track lots and never blew it up so the bottom end is safe for anything you want if its tuned right.

[will_c]

budget will be around 3 grand.
so you rekon a fully rebuilt bottom end will be fine for 400 bhp?
I ll be having a custom manifold and exhaust made up
not sure on management yet... stand alone system... i had a DTA for my rover but never got round to fitting it.

[Ant]

spend the £Â£ on getting the head welded, some uprated head bolts( metric blues or M30 type 12.9grade ) and give the bottom end some new shells and bolts, dont forget to add a new oil pump, or at least change the gears in the top , just to be doubly sure M8

the rest is well up to task at hand

What turbo you planned to use ??
What type of manifold have you gone for ?
external or internal wastegate??
What size downpipe ?

lots to think about m8 Check out Fozzymonsters posting for ideas on the pipework, the downpipe is the limiting factor as there's no clearance on the steering

use the DTA if you still have it

[will_c]

planning on using a Garret GT2871r with internal wastegate. Not sure on manifold yet... any ideas? was planning on a custom one.
What am i limited to with the down pipe issue?

Just like to say, what an awsum forum! really really good! Thanks!

[Ant]

planning on using a Garret GT2871r

dude, torque monster turbo(small), you after an all rounder or top end ?

My T3 in 60 trim boosts @2.2K , monster torque up to 5.2K but HP suffers up top

[will_c]

Well this car is going to be built for acceleration and will mainly be used on the track so i dont want a big laggy turbo.
GT2871r can flow 400 bhp and has minimal lag

[e30_Turbo]

Well this car is going to be built for acceleration and will mainly be used on the track so i dont want a big laggy turbo.
GT2871r can flow 400 bhp and has minimal lag

The GT2871r is too small dude, it can flow 400bhp but not on a 2.5ltr engine.

This turbo is great for small displacement engines up to 2.2L

I'd suggest something like a Garrett GT2876R (aka GT25/40R) but I'd rather say get a Holset

HTH, Mark.

[will_c]

ah yeh, im still in 2ltr 4 pot mode!
whats a Holset?

[maxfield]

www.holset.co.uk