how to build a powerful 2.7? most powerful built?

[oakey]

2.8 has the same bore and stroke correct? so it's a square engine - i've never read anything about the character of this. Theres plenty to read on over or under square lumps

As to saying they don't rev like a 2.7 thats rubbish E30Adams 2.8 revved very well

if you can find some alpina pistons you can use these with an eta/td crank and 325i rods and off you go, no decking or vernier pulleys needed

not disbuting what your saying but how can a 2.7 and a 2.8 have the same bore and stroke?

He's not saying the 2.8 and 2.7 have the same bore and stroke, he is saying that the 2.8 is a square engine.

1an- I dont see why you wouldnt want to go bigger?! Why not go for a 2.9 stroker kit? I think you can get a 3.1 also

[maxfield]

No the crank has a stroke of 84mm and the bore is 84mm. Therefore a square engine.

[HairyScreech]

the 2.5 is well over square, the 2.7 is only slightly oversquare and the 2.8 is square. its onle a mm or so between the 28 and 27 is is not? 324d is 83mm stroke isnt it? as far as revs are cncerned thats going to make sweet fuck all difference in real world terms, and anyway when was the last time you had your engine revving to the limit of its components.

in everyday driving the weight and reletive mass of the comonents is more important as it will dictate the speed the engine will gain and loose revs.

imo your would be a fool to make a 2.7 when you already have a 2.5 as all you would need for the 2.8 is a new crank, a spacer and some 320 rods.

for a 2.7 you would need the block decked and a verniaer pully ontop of everything else and for the extra money you would loose 100cc.

[Simon13]

Hairy get you facts straight

325 - 84mm bore 75mm over square

327 - 84mm bore 81mm stroke undersquare

328 - 84mm bore 84mm stroke square

All these engines behave differently and those few mm make all the difference to how they rev and the power they make. The 2.5 rev's well the 2.7 is classic undersquare with good torque but doesn't rev quite as well as a 2.5 can be made to

He also needs 320 rods for a 2.7 unless you aquire some alpina pistons. Then all you need is a crank - so which is easier then!

[march109]

2.8 has the same bore and stroke correct? so it's a square engine - i've never read anything about the character of this. Theres plenty to read on over or under square lumps

As to saying they don't rev like a 2.7 thats rubbish E30Adams 2.8 revved very well

if you can find some alpina pistons you can use these with an eta/td crank and 325i rods and off you go, no decking or vernier pulleys needed

not disbuting what your saying but how can a 2.7 and a 2.8 have the same bore and stroke?

He's not saying the 2.8 and 2.7 have the same bore and stroke, he is saying that the 2.8 is a square engine.

1an- I dont see why you wouldnt want to go bigger?! Why not go for a 2.9 stroker kit? I think you can get a 3.1 also

Your talking about the IE kits, and they require custom pistons and the block to be over bored. I don't think there is enough cylinder wall too do much of that withought weakening the block. Withought the IE kit it would be an arse to source all the parts to do this yourself. For example crank shaft with 89.6mm stroke, light weight forged Pistons, piston rings, high strength wrist pins, and main bearings ect ect ect, then have it all balanced and mod the bottom of the bore for the rods to clear.

[StuBeeDoo]

Hairy get you facts straight

325 - 84mm bore 75mm over square

327 - 84mm bore 81mm stroke undersquare

328 - 84mm bore 84mm stroke square

Got the first one and the third one right and the second wrong Simon.

Square = bore & stroke identical
Undersquare = stroke longer than bore
Oversquare = bore larger than length of stroke.

327 is oversquare.

[HairyScreech]

Hairy get you facts straight

325 - 84mm bore 75mm over square

327 - 84mm bore 81mm stroke undersquare

328 - 84mm bore 84mm stroke square

All these engines behave differently and those few mm make all the difference to how they rev and the power they make. The 2.5 rev's well the 2.7 is classic undersquare with good torque but doesn't rev quite as well as a 2.5 can be made to

He also needs 320 rods for a 2.7 unless you aquire some alpina pistons. Then all you need is a crank - so which is easier then!

thats why i said "324d is 83mm stroke isnt it?" hence the question mark at the end, as i was asking if it is. and the rest of my coment still stands, a 2.8 with lightened components will rev better than a 2.7.

the point of saying he needs the 320 rods was that he would need less parts to build a 2.8 out of a 2.5 then he would need to build the 2.7.

can you still get alpenis pistons? and whats the price on those?

[HairyScreech]

isnt turbo brown using the IE crank and normal 84mm bore pistons?

[march109]

isnt turbo brown using the IE crank and normal 84mm bore pistons?

I don't know is he? I don't know what crank IE use, I'll have to ask him.

[HairyScreech]

Happyness and joy, will mine be the first E30 to feature not one, but two Holset turbos?

Cheers to Fozz for the heads up on a dinky little HX27 which set me back the princely sum of £90! Gotta love the brand anonymity of Holset, God knows how much the equivalent Garrett would've gone for.

So, here's the spec so far:

2 Door shell (to have it's diff mount reinforced!)
2 Litre block to be bored to 84mm
2.9 stroker kit from Ireland Engineering featuring forged crank, steel rods and forged pistons (it'll work out at 2791cc if I keep the bore to 84mm instead of 85mm)
Holset H1C
Holset HX27

Be interesting to see where this leads!

Cheers!

Alex

looks like he is, just lifted that from his thread.

[march109]

When I PM'd him last it seemed alot of the e30tech boys had put him off. Apparently the parts could be sought seperatly cheaper.

I wonder if he has bought it, if he knows what crank IE use? I assume the cranks for their 3.0 and 3.1 kits are the same, but not sure on they're 2.9 kit, again I would assume its the same as the M52B28 crank.

[Simon13]

it's 81mm

324td 81mm
eta crank is the same and made of chocolate!

[Ant]

Harsh Si, not chocolate dude, they work well up to 7K, 7.4K in bursts(not sustained) PROVIDED there are no ETA heavyweight slugs hanging off the end of the rods.

I can't believe were having yet another 2.7 thread

for the record, Adams 2.8 made LESS power and torque than it should have given the spec and CR( only my opinion guys, thats NOT gospel ), but sometimes they can fail to become more than the sum of the parts used, no matter how hard you try.

Ian, you been for a drive yet BTW ?

[Turbo-Brown]

I'm using a 2.8 crank (84mm stroke) and forged 85mm JE pistons now as it worked out WAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAY cheaper than the IE kit!

This whole "revviness" debate always seems to leave out one vital part of engine design:

An engine of a given capacity, say 2.0litres, can have pretty much any bore / stroke combination. What dictates it's "revviness" to the largest extent is the bore size for one simple reason: if you have a large bore, you can get large valves in.

It's not piston speeds or weights etc which effect an engine's ability to rev, it's whether or not it can breathe.

Now if you increase the capacity of an engine but don't increase the ability of the head to breathe, it probably will become less "revvy", but whether that capacity change comes from a stroke change or a bore change probably won't have all that much effect on that "revviness"

[Jhonno]

also under or over square isnt the full story of revs.. Valve area is, which is normally associated with oversquare lumps.. the norris evo thing was v undersquare iirc yet revved to 8k

weight is another factor..

[oguz327]

Interesting thread

[1an]

Oz which way was your engine built?

[oguz327]

Oz which way was your engine built?

Basic spec

325 head
eta block (decked) and crank
early 325 pistons
cam
vernier pully


Speak to Ant for full spec dude!

[I am not very bright]

I am looking to do a engine rebulied myself but i am on a tite buget

[1an]

Oz which way was your engine built?

Basic spec

325 head
eta block (decked) and crank
early 325 pistons
cam
vernier pully


Speak to Ant for full spec dude!

so its the way ive been looking into over on e30tech, and this makes quite nice power doesnt it if im not mistaken

[Simon13]

the best 2.7 i've experienced imo was the old GUG engine. Loads of low end grunt and plenty of HP up top too

It did everything well if you get me

[1an]

makes sense Simon, wasnt that a les stanard(sp) built engine?

[fowler]

Ian just Turbo a stock m20B25 if it can take my abuse i am sure you can not break one plus you will scare yourself shitless with 25o BHP coming from a weezy 1.6
plus ther is no point using a tired 2.5 block sort out what you want to do !! plus you have to stick to a budget of dull money and shirt buttons LOL !!!

[jaistanley]

I'm inclined to agree with the FI option... (just to stick my tuppence worth in)..

I can completely see why 1an wants to build a nice 2.7 with exotic materials and a high revving nature.. I was an automotive engineering student and things like that make me go oooooh. But I'd still vote for the FI. Despite having a bad rep for reliability, you'd be boosting fairly low so I can't forsee any great difficulty for the engine. The extra torque lower down would make the car a lot faster in general. Yes, on a track a well tuned NA engine might be more suitable but in a narrow band. The extra torque gives you much more effective power. As my lecturer's used to say.. Its the area UNDER the bloody graph, not the number at the top..

All that said and done I did it the other way and went and found myself an S50.. Some other mug had paid for all of the development and all I had to do was sling 3k at it and be able to replace it with stock bits if I broke it. Should be making the same/more torque, 50 hp more power at least and use less fuel. Good for pu talk too... LOL

I can't quite understand why you discount the 24v engines. We're not talking a model T ford here. IMHO the E30 is just a fun car to play around in, not some sort of holy entity that must be kept pure. I understand the argument about not using a 2.8 crank even less.

Good luck with whatever you choose dude.

Jai

[1an]

Ian just Turbo a stock m20B25 if it can take my abuse i am sure you can not break one plus you will scare yourself shitless with 25o BHP coming from a weezy 1.6
plus ther is no point using a tired 2.5 block sort out what you want to do !! plus you have to stick to a budget of dull money and shirt buttons LOL !!!

correct me if i wrong but yours is in Ants workshop broken.

dont claim no dull money thanks, like ive said its planed for long term i.e over this year. ive made my mind now i want a 2.7 no changing and dont want f/i.

plan is to chuck the 2.5 in now then build myself a rebuilt 2.7, with all the trimmings.

[JazzMan]

My 2.8 build has cost £100 for an M52B28 block I pulled the crank out of, £20 for the conrods from a zoner, £100 in machining work and testing on the head, £350 in various bearings, bolts, water pump and gaskets and other parts. I wasn't going for an out and out top quality as new rebuild - that would have cost substantially more and involved replace a lot more parts.

Capacity increase + a diy referb of the important parts. I also got a new cam and valve springs (I think about £250). I picked the 2.8 route because it was less complicated than the 2.7 + 100cc extra can't hurt and I already had a nice 6 branch manifold I didn't want to drop in favour of FI (there's always the supercharger option in future!).

The expensive bit will be Megasquirt to run it all

Not sure what kind what torque / power I will end up with but it should be a chunk more than before which will make me happy.

[cliffybabe]

ian is gonna go 2.8 i can see it coming

[HairyScreech]

seen as theres more m20b28 engines being built is anyone willing to make a motronic (moronic) chip like the alpina and basic 2.7 chips?

[cliffybabe]

Ian just Turbo a stock m20B25 if it can take my abuse i am sure you can not break one plus you will scare yourself shitless with 25o BHP coming from a weezy 1.6
plus ther is no point using a tired 2.5 block sort out what you want to do !! plus you have to stick to a budget of dull money and shirt buttons LOL !!!

correct me if i wrong but yours is in Ants workshop broken.

u gotta laugh

Besides everyone knew ben would even break the engine or write the car off

[oguz327]

Apart from Jazz, Scott Player and Adam/Andy, who has built a 2.8?

As said before, everyone talks a good 2.7/2.8

[oguz327]

the best 2.7 i've experienced imo was the old GUG engine. Loads of low end grunt and plenty of HP up top too

It did everything well if you get me

So you keep saying Simon

[cliffybabe]

Apart from Jazz, Scott Player and Adam/Andy, who has built a 2.8?

As said before, everyone talks a good 2.7/2.8

well said

[1an]

ian is gonna go 2.8 i can see it coming

nah 3.1 stroker,

problem i have with going f/i is that i will keeping turning the boost up and up and up untill it goes bang. with n/a i cant do this.

2.7 in my opinion is also proven to give a nice driveable engine with alot of torque but i want to build it so it revs like a nutter, every little move of the throttle and the engine will respond is what i want.

im not disregarding an m50 becuase trust me i really want one but not in this shell, that will come but probally in diesel power as my every day car.

[JazzMan]

We'll see if mine runs or not over the next few weeks

[fowler]

correct me if i wrong but yours is in Ants workshop broken.

dont claim no dull money thanks, like ive said its planed for long term i.e over this year. ive made my mind now i want a 2.7 no changing and dont want f/i.

plan is to chuck the 2.5 in now then build myself a rebuilt 2.7, with all the trimmings.

the reason mine is there is because i have taken an M20 or should i say Ant has taken it to a completely new level and its having some teething issues like every ongoing project. soon to be released with more BOOST
if you want to get in to a pissing contest we can, but to be truthfully honest don't waste your time with the B25 as its mayoing all over the place just build something properly. as you have pointed out!! oh by the way i was extracting the urine and i don't need any of your bovine scattery!!! thanks !!