2.7 or 2.8, 2.7 it is Powered by Nelly, Finished

[dips346]

A genuine 230tq would be an unbelievable achievement and would be far from easy IMO, thats in excess of what a S54B32 makes in Tq / displacement (BMEP). Alpina claim 213lbft from a 2.7 and even that is excellent for a 2V street engine.

to get 220 bhp from a proper 2.7 is not that hard ,plenty on the zone ,

I agree.....but thats not what point i was making. Torque is a strong function of displacement and try and find any modern NA production engine that makes 85 lb-ft/L much less a 2V per cylinder one (hint you probably won't find any) and that hints as to how hard it is. Its much easier to make 220hp.

my bad ,true ,to get Torque it does cost

[cliffybabe]

pickingup my 2.7 chip from Ant tomorow to get it running right and later in the year ill be getting it setup on a rolling road im so excited

[Andyboy]

IMO it's not really worth going 2.8 over 2.7 in the expectation of loads more power because you ain't going to get it. An extra 100cc on a 2.7 litre engine will never give a lot more in the same way an extra 100cc would on a 1600 Ford Xflow for example - it's all relative. Plus the 2.8 has extra con rod angularity and thus more friction and piston dwell at TDC (curable with long rods and custom piston).
The 2.8 thing will be more popular because 2.7 Eta cranks are starting to get scarce now, especially good ones that don't need an expensive regrind. 2.8's have been around since 1995 and there are increasing numbers of shagged 328i's and E39 scrappers with block problems. From here we're going to see more broken 3 litre M54's..........

[march109]

Yes the M54 crank would make some prettty meaty M20 strokers.

[reggid]

IMO it's not really worth going 2.8 over 2.7 in the expectation of loads more power because you ain't going to get it. An extra 100cc on a 2.7 litre engine will never give a lot more in the same way an extra 100cc would on a 1600 Ford Xflow for example - it's all relative. Plus the 2.8 has extra con rod angularity and thus more friction and piston dwell at TDC (curable with long rods and custom piston).
The 2.8 thing will be more popular because 2.7 Eta cranks are starting to get scarce now, especially good ones that don't need an expensive regrind. 2.8's have been around since 1995 and there are increasing numbers of shagged 328i's and E39 scrappers with block problems. From here we're going to see more broken 3 litre M54's..........

the shorter rod ratio of 2.8L will reduce dwell at TDC but its peanuts really, for example the 2.7L will spend an extra 0.3 degrees (22.15* vs 21.85*) at 1mm or less from TDC and 1.8* difference at 10mm.

The same with extra angle its about 3.5% extra not really a problem unless you get a even bigger M54 crank (10% extra angle with eta rod) and the neccessary short skirt custom pistons which require larger clearances but you wouldn't use the Eta rod in this case so you can reduce it like you say with different rods and custom piston.

[oakey]

to get 220 bhp from a proper 2.7 is not that hard ,plenty on the zone ,

I agree.....but thats not what point i was making. Torque is a strong function of displacement and try and find any modern NA production engine that makes 85 lb-ft/L much less a 2V per cylinder one (hint you probably won't find any) and that hints as to how hard it is. Its much easier to make 220hp.

my bad ,true ,to get Torque it does cost

My relatively low spec 2.7 made 225ftlb and I dont think it was running perfectly either.

[cliffybabe]

and my eta bottom end is a high comp version thanks again Gareth

[reggid]

I agree.....but thats not what point i was making. Torque is a strong function of displacement and try and find any modern NA production engine that makes 85 lb-ft/L much less a 2V per cylinder one (hint you probably won't find any) and that hints as to how hard it is. Its much easier to make 220hp.

my bad ,true ,to get Torque it does cost

My relatively low spec 2.7 made 225ftlb and I dont think it was running perfectly either.

An interesting read.

http://www.pumaracing.co.uk/POWER2.htm

[oakey]

^ Aye. Tis a very good read! It pretty much says that 225 ft lb is near impossible from a 2v per cyl 2700cc engine. Hmmm. That is 83.3ftlb per litre

Quote:
It is hard to get even a race 2 valve engine to produce much more than 75 to 78 ft lbs per litre and for a 4 valve engine more than 85 to 88 ft lbs per litre.

[daimlerman]

2.7's are all about torque.It is torque that fires you out of a bend or gives the grunt to overtake.BHP is just a number that you boast about down the pub.On zone roam,the 325's were dropping one or even two gears to overtake or climb a mountain,I was tooling along in 5th!!And I recorded the best fuel consumption...as long as the car is rolling,first gear is redundant,I pulled it out of a hairpin on the Applecross road in second,and that was with the nearside on gravel and Calamity Jane convinced that she was about to get very intimate with the rock face..

[Ant]

Neil, if you're rebuilding the ETa( and I would !! , bearing in mind the low friction mains and big ends are only designed for 5.2K max rpms ) then TBH I'd drop in the B25 slugs and do the job properly.

885 head with flat top Eta slugs does work, but you have to run less timing to prevent det @ peak Torque, and the result is less overall power, I'm sure 100+ "experts" will arrive soon and shoot that statement down in flames, but the two heads use radically different pistons for a very good reason.......

I've yet to see a 2.7 with the eta/885 combo make more than 213hp, and that was with a 288 cam, BBTB, BTB and Unichip/MAF combo( a 5K+ rebuild in total )

Oz's made 225.6 HP on stock motronic 1.1, thats the benchmark IMHO

[march109]

Ant - Neil has a BBTB and 6 branch (alpina iirc) already, and when we spoke was happy with 190-200ish bhp. I know he also planning on a cam (unless plans have changed) so what do you reckon his bhp aspirations should be so as not to be disappointed?

[march109]

And FYI neil isn't looking for balls to the wall power, just a nice smooth running engine with a bit more torque and power than a regular 2.5L after all its going into a scuttle shaker, this isn't a race engine build and neil won't pretend it is, this will also be built to a very reasonable budget.

and the engine had 98k ish miles on when it was liberated from the donor.

[Demlotcrew]

Would it not be best to use a custom Rod and not deck the block? That 2m extra on rod length would do wonders for more power!

A

[Ant]

SO the buzzword here is cheap.....

In that case, I'd still reshell the ETA and drop a new oilpump in there for good measure, plus a good glazebust and re-ring, that said. you're only £150 max of machining and the cost of a vernier , piston and combustion chamber matched, full fat 2.7 with the correct crown shape on the slugs.

Custom rods are OK but custom slugs on the B25 rods must be the better choice ? less rod angularity no.

For what cliffy is trying to achieve, the BK 2.7 will suffice methinks, more TQ than HP for the chromed scuttle wagon.

[Demlotcrew]

Quite right Ant - the way to get less rod angularity is with custom pistons and B25 rods, but if you are going all that way why not get a extra few mm's from custom rods too

^ Above is over decking the block.

I would use custom pistons with a 20mm wrist pin and max out on the length of the rod. You could even go to 2 ring pistons and use a even longer rod for extreme power!

[Ant]

Sorry dude, I was referring to the Alpina spec using the 81mm crank with the 135mm rods and the oddball Mahle slugs

gives the longest possible rod with that crank in the B25 c-case, gives the C2 2.7 its characteristic piston slap from cold too.



Sorry Cliffy a little OT but its the zone, and thats what we do best

[Demlotcrew]

135mm the Stock S14's are 144mm and my next engine is going to have 147mm

Nice car Hap!

[pacerpete]

135mm the Stock S14's are 144mm and my next engine is going to have 147mm

Nice car Hap!

You obviously haven't seen it !

[reggid]

SO the buzzword here is cheap.....

In that case, I'd still reshell the ETA and drop a new oilpump in there for good measure, plus a good glazebust and re-ring, that said. you're only £150 max of machining and the cost of a vernier , piston and combustion chamber matched, full fat 2.7 with the correct crown shape on the slugs.

Custom rods are OK but custom slugs on the B25 rods must be the better choice ? less rod angularity no.

For what cliffy is trying to achieve, the BK 2.7 will suffice methinks, more TQ than HP for the chromed scuttle wagon.

what rods does Oz's use?

[cliffybabe]

its a cab at the end of the day and th elast things i want is the chrome peeling off to be honest i just want areliable strong engine and the thought of a 2.7 seemed a good one, As Gareth said really

Im quite happy with my bbtb alpina 6branch and my 3.9.1 slipper and Ants 2.7 chip

thanks
neil

[cliffybabe]

Its complete im well happy with it looking forward to the Dyno next Monday

BIG THANKS NELLY

[JazzMan]

Awesome that was quick!

[OBs]

Awesome that was quick!

Pah my Mum could of doneit quicker

[siddiqi1]

my god; i thought Ant and Demlotcrew werent going to stop

what a load of language ive never heard of before; they took it to another expertise level there! my head hurts

[Nelly]

BIG THANKS NELLY

Your welcome squire - now enjoy