My e30 BMW 2.7L

[johnt0709]

is it not easier just to look at the guys dyno chart - does it reflect a 2.5 or 2.7?

[march109]

is it not easier just to look at the guys dyno chart - does it reflect a 2.5 or 2.7?

neither, hence why more investigation is required.

Its either a very poorly 325i, or a completely shagged (or restricted in some way) 327i, but cerainly no 320i.

Since no one knows the details of the supposed 2.7l build anything is still a posibility, the only sure fire way to tell if its a 2.7 is to check the stroke, procedure detailed above.

320i and 325i share the same stroke but different bores, we can nearly 100% rule out it being a 320i based on power, head, intake and throttle body though.

[johnt0709]

not good news either way then

hopefully a restricted 2.7

[StuBeeDoo]

320i and 325i share the same stroke but different bores

Not true.
320i = 80mm bore/66mm stroke
325i = 84mm bore/75mm stroke

Its either a very poorly 325i, or a completely shagged (or restricted in some way) 327i, but cerainly no 320i.

Agreed. FWIW, my money's on an eta with an 881 'head and issues.
TBH, I can't see it being a poorly 2.5, it's making too much torque.

[afcbob]

Why is it only rev to 5k when doing the rolling road

[GeoffBob]

.. the power and torque curves cross at 4500rpm.

What does it all mean?

I spotted this too Stu and immediately started banging away on my keyboard about the dynograph being faulty. Luckily, before I finished, I spotted the fact that the torque and power curves are on different scales - so technically they don't actually cross at 4500 rpm.

For those that don't know what this means, power is related to torque according to:

HP = (RPM x T)/5252

where HP is the engine power in units of hp, and T is the engine torque in units of lbs-ft. Hence, provided the power and torque curves are on the same scale, they should cross each other (intersect) at exactly 5252rpm. So at first glance this dynograph looks dodgy. On closer inspection though, the numbers do check out.

I do however suspect that the x-axis (rpm) of the graph is faulty. I would be interested to hear how the rolling-road operator measured the engine speed. Did he pop an inductive clamp around one of the plug leads (and then tell his PC that it was an I6 engine) or did his PC calculate the engine rpm from the roller speed (by telling his PC the final drive ratio and gear ratio for that model vehicle).

If the latter is the case then its possble that he assumed the car had a diff from a 325, while it quite likely still has it's original 320 diff fitted. The good news afcboc is that if this is the case then the x-axis of the graph simply needs to be rescaled, and the engines power output recalculated (which will be more than that currently shown).

This is just one possibility. So the question is, how did the dyno-man determine the engines RPM while he was performing the test?

[jermyns]

It may have the eta chip in there.

Before I started to all of the work on my e30 myself I had one of the local BMW tuners looking at it from time to time. Unfortunately he was a bit of a villan and at one point removed the programed chip that was in there making the most out of the 2.7 litre thinking I wouldn't notice. Unfortunately he was right, I went a few months without going for the redline, but when I did it hit the wall at 5krpm. Figured out what this heap of steaming turd had done and went back to confront him. Shop closed, no forwarding address.

Do all of my own work now.

[schnaarf]

Redline at 5k? That's not right on any e30 except maybe the 325e

[GeoffBob]

Redline at 5k? That's not right on any e30 except maybe the 325e

Quite so. But then from what I have read through this thread it sounds as if the OP has a 2.5l ETA engine converted to 2.7l (by means of 81mm stroke crank and new rods) with type 885 head and now the possibility that the original ETA chip was put back by some unscrupulous person. From the OP's other thread on this topic m-jermyn seems to have done an excellent job of identifying that car does in fact have the correct ECU (non-ETA), but it now seems that the EPROM could have been swapped back for the ETA chip.

afcBob, So long as the rolling-road operator measured the engine rpm correctly during the test then I think that this one may be explained.

[m_jermyn]

Geoffbob I read through your other post

You need to tell me how the rolling road operator measured your engines RPM. Did he put a clamp on one of the plug leads, or did he calculate your engine speed based upon the speed of the rollers? The reason I ask is because I think the x-axis (RPM) of your graph may be in error.

I suspect you are right on this mate.... I was looking at his dyno thinking the bloody thing just drops off at 5000... Just like a ETA does... thats why I wanted to know what ECU he had.. I suspect the eta one, But he does have a 325i ECU, I then told him it should rev to 7000.

His reply

It does rev to 7000 when am driving it

Could this just be down to Dyno operator error?

[GeoffBob]

Could this just be down to Dyno operator error?

I am inclined to think so, unless someone has indeed swapped the EPROM chip out of afcbobs motronic ECU back for the ETA version. TBH, I am not even sure if this is possible, so would be interested to hear what others say in this regard.

Operator error does however seem more likely to me. If the operator measured the engine speed off the HT wire from the coil to the dizzy, and had previously tested a V8 engine (ie: software was still set to 8 cylinders) and he forgot to set it down to 6 cylinders, then the RPM indicated on the graph would be 75% of what they really were. In other words, 5000rpm indicated on the graph is actually 6666rpm in reality.

The other possibility is that the operator determined the engine RPM from the roller speed, and assumed the car had a 2.93:1 diff in it (where as it possibly still has its small case 4.1:1 left behind from its days as a 320 ”“ TBC). Now why the operator would assume a 2.93:1 diff I wouldn’t know. Possibly he mistakenly selected a 325e from a drop-down menu in the software? Or maybe that’s what the car tested before had on it and he forgot to change the setting ”“ who knows.

Afcbob, assuming this was the mistake he made then the dynograph would look as follows:



To get this I took the liberty of reading the torque data-points of your posted dyno-graph. I then re-plotted them having recalculated your engine RPM. Since your RPM are now higher than before I recalculated your engine power (which is the product of RPM and torque). This may look a little more along the lines of what you were expecting, but please don't take it as gospel until we fully get to the bottom of this one.

[afcbob]

Ok Thanks for all the help guys on this one i will be getting in touch with the Operator of the Rolling road to find out what he says.

I will update this once i get a reply from him

and thanks again for the help.

[afcbob]

This was there reply

The dyno doesn't need to know what kind of engine is in the car for it
to work out the power.

The dyno is teaches the PC at the start by holding the car at 3k RPM in
the gear used to run the car.

Then for the power runs the computer will work out the power from the
ramp rate on the run & coast down.

There is no need to input engine code/type or gear ratio for it to work
out the power.

[GeoffBob]

Fair enough. That's one way to do it, albeit not the most accurate.

In which case the operator didn't hold your engine at 3000rpm while he was teaching the PC, he was in fact holding it at 4000 rpm (dozy twonk should have had his eyes open). That clearly explains why the dyno-graph falsely indicates that your engine was red-lining at 5000 rpm (at least that's what the PC thought your engine was doing), while your engine was in reality on the edge of 6700 rpm!

[afcbob]

So does this mean that it was just down to that why the BHP is wrong or is it the ECU.

[GeoffBob]

RPM was wrong Bob. And because power is calculated from torque multiplied by RPM, then so was the power.

Click on that dyno-plot that I plotted for you above and have a good look at it. That's based on the torque data that I extracted from your dyno-graph that you posted. That is (more or less) what your dyno-graph would have looked like if your dyno operator had been paying attention.

Kindly note that I am taking you at YOUR word that you can in fact run this engine up to 7000rpm for real on the road. That tells me, along with m-jermyns efforts, that you don't have an ETA ECU in your car. I therefore can't see any other reason than operator error for your problem.

And now you have reason to smile . It looks to me as if you are at least making 210hp at the flywheel, and that you do indeed have a 2.7 under your bonny wee bonnet .

[m_jermyn]

Geoffbob your a master....

As far as the eta chip in the 325i goes the eta ECU has two rows of pins while the 325i one has three.... I dont think they are interchangeable..

afcbob sounds like it a quick car, I would be reeeeeeeaaaaaaaalllllllllllyyyyyyy happy with that.

Great effort

Mike

[afcbob]

Right a update i had her out this morning to see what see redlines at just to makes sure and she redlined at 6500k

Does this change anything?

m_jermyn

Am more than happy with the car i love it as its my 1st BMW been wanting one since i was young

[GeoffBob]

Right a update i had her out this morning to see what see redlines at just to makes sure and she redlined at 6500k. Does this change anything?

Nothing changes, sounds about right to me.

Would recommend that you out her back on the dyno if you want to satisfy your own curiosity, but I think you'll find your power curve will be similar to what I posted above.

[jermyns]

2.7i....niiice.

Tooling around at 1500rpms in top...foot down and it pulls away effortlessly...steep long winding hills where you are still accelerating in 5th when you breast the top.

This is motoring BMW style at its best. Congratulations on a great car.

[E30-MANIAC]

enjoy her mate and take care of her

[afcbob]

Yeah wil be putting her back on a dyno, as i think it would be good to have the right power to go with the car.

And thanks again for all the help.

[m_jermyn]

Not a problem glad we worked it out.... If you live near Atech take it there.. fastbimmer.co.uk i think

[afcbob]

No no where near it am up in Scotland

[octanejunkie]

Pukka looking car, i hope you've got the spec sorted now.

They look great in white.

[afcbob]

Sad news about my car some time ago now about a year ago some little 14 year f**ker thought it was that nice he would take it.

and was so nice of him taking it he also did this



But to top it all of is due to it been righting off 2 before now the 3rd time i was not getting it back.
Aslo the guy i got it from must of fixed and put it back on the road to sell it as it was just before i bought it


It pissed me off that much i did not want to buy a new e30.

But now missing the joy of driving a e30 i wish i could get one again

[mani]

shoot

[mani]

it looked nice

[Greeny]

sorry to see the e30 in that state, thieving f**kers want their hand cutting off.
Buy it back off the insurance and get the motor stuck in another one.

[afcbob]

They would not let me due to been a write off for the 3rd time it had to go to Mr Scapland poor shame as it would be easy sorted

[knuckledragger]

this is odd as my my 1988 e30 touring has a2.5/2.7 casting on the head and stamped in the little rectangle bit at bottom of the n/s of engine it says 2.7 is this a origanal 2.7 block as i was imformed by last owner it had been stroked

[afcbob]

Need to find a new one soon missing the e30 now