Eta: Why the 4600 RPM Redline? Truth be told

[gotKRAUT]

A lot of miss information and questions led me to this thread.

The Eta was designed to be a daily driver. Good efficiency, lots of low end torque and almost 0 engine wear. How did they do this?

1) Soft Valve Springs
2) Lower tuned cam
3) SUPER soft piston Rings
4) Long Narrow intake manifold Runners
5) Efficient Chip Tuning.
6) Not to mention the Connecting rods are super weak

No i am not talking out of my @$$, this is all from the mouth of a 20+ year BMW Master Technician

if you want RPMs out of an Eta you would literally have to do the following
1) I valve Springs
2) I cam or more aggressive
3) Aftermarket Pistons to get the right CR with number 4
4) I connecting Rods
5) Stronger piston rings
6) I intake Manifold (Requires port maching the head)
7) I injection
8) I ecu

point being, its way too much work to get a 2.7 stroker this way, just buy a B25 and swap over the crank and get some aftermarket pistons and BAM your set... But, it is possible to get the revs out of the Eta, using the steps above(only thing Eta remaining would be the Case and crank lol)

[nukeduster]

con rods arent weak, thats actually false.. everything else is true. biggest thing preventing revving is the valve springs, i've setup an eta with dual valve springs and it was able to rev, just didnt make any power without a swapped out aftermarket cam.

next, if you want to rev above 7k would be rocker arms. have to go micropolished or billet. billet are sexy. yummy.

[triggrhaapi]

Meh, rocker arms. Revving out an Eta is silly.

[ldsbeaker]

Eta's with S50's are cool.

[gotKRAUT]

Originally Posted by nukeduster

con rods arent weak, thats actually false.. everything else is true. biggest thing preventing revving is the valve springs, i've setup an eta with dual valve springs and it was able to rev, just didnt make any power without a swapped out aftermarket cam.

next, if you want to rev above 7k would be rocker arms. have to go micropolished or billet. billet are sexy. yummy.

Well i guess BMW is mistaken then on the conrods they installed in their motors

My Previous Eta had i cam, i springs, i intake manifold port matched to the head and i injection, thus i had the i DME also..never revved it past 6k though i have always been told the conrods are a weak point from more than one BMW Tech now, so no offense i will take their word over yours nothing personal, for all i know you could be right i have never load tested them side by side..

maybe they ment the con rod bolts? i dunno i also remember hearing in passing that the main bearings were softer too just like the piston rings just to prevent wear but that one is just hearsay for now, i wanna yank an Eta and "I" apart and just compare everything side by side

[gotKRAUT]

aparently a lot of people are misconceiving the entire point of this thread. I am not saying this is what you should do to make an Eta Faster. This is simply answering the question of how to get the engine to REV HIGHER. which is pointless but this is how. Thanks i will be here all week..

[KMFDMR]

Okay.. Well, this is a point I'd thought about myself, so thanks for bringing it up, gotKraut.

From a marketing perspective, when the eta engines were released, they were filling the gap that the diesels in the BMW range fill today. They were built to be low-revving (low wear), torquey, fuel efficient daily drivers.

What is possible to do to the eta to make it rev is irrelevant - why would you spend the money? By the time you get all the conversions done, and everything is sitting pretty, you may as well have sold the Eta, gone out and found yourself a slightly worn 325iS and had it's internals given a nice sprucing. Financially, it's backwards - if the Eta was meant to rev, BMW would have made it that way.

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KMFDMR

[Starmavin]

Originally Posted by KMFDMR

Okay.. Well, this is a point I'd thought about myself, so thanks for bringing it up, gotKraut.

From a marketing perspective, when the eta engines were released, they were filling the gap that the diesels in the BMW range fill today. They were built to be low-revving (low wear), torquey, fuel efficient daily drivers.

What is possible to do to the eta to make it rev is irrelevant - why would you spend the money? By the time you get all the conversions done, and everything is sitting pretty, you may as well have sold the Eta, gone out and found yourself a slightly worn 325iS and had it's internals given a nice sprucing. Financially, it's backwards - if the Eta was meant to rev, BMW would have made it that way.

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KMFDMR

You should also read my thread called "Luke, use the torque...."

[nukeduster]

Originally Posted by KMFDMR

Okay.. Well, this is a point I'd thought about myself, so thanks for bringing it up, gotKraut.

From a marketing perspective, when the eta engines were released, they were filling the gap that the diesels in the BMW range fill today. They were built to be low-revving (low wear), torquey, fuel efficient daily drivers.

What is possible to do to the eta to make it rev is irrelevant - why would you spend the money? By the time you get all the conversions done, and everything is sitting pretty, you may as well have sold the Eta, gone out and found yourself a slightly worn 325iS and had it's internals given a nice sprucing. Financially, it's backwards - if the Eta was meant to rev, BMW would have made it that way.

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KMFDMR

if my 540i was meant for racing and destroying camaros and rustangs and evos then they might have made it that way too.. doesnt mean i'm not gunna build it up for the power and handling to destroy 80-90% of the vehicles on the road today...

some people dont like buying M's straight up, but making them unique to their liking (i like e34's and the m5's torque output is actually lower then my 540is anyway...plus my car has an affordable supercharger available.. m5.. no sir.)

[KMFDMR]

Lol. Dude, a 540i was designed stocko-blocko with a 286Hp - largest output in a car at the present time, barring the M5 - V8.. Slightly different situation, and as such your argument kinda shoots itself in the foot.

The fact is that a 540i was made to be a musclebound machine - lots of torque, lots of power it was made to possess these things. These developments you're talking about are congruent with the design of the 540i. Consider that effectively, 'wise' car makers build a perfomance engine like yours, test out what it can do and wind it back about a 1/3 of the way - so that Joe Bloggs doesn't rev the nuts of it, and put a piston through the header before the end of the warranty period.

The Eta on the other hand, was not made to rev, so performance upgrades to that end are kinda silly from my point of view, when there a perfectly good alternatives to do up (which there aren't in the E34s - I'd take a 540i over an M5 or the 3.0 V8 anyday; nicer engine, without the 'prestigious' pricetag). Having fanged my share of E30 trade ins, (including a Evo II M3, which was a grinner), the 325iS was the pick of the bunch from a perfomance point of view if you couldn't justify the dosh for the M3, and also from a modification point of view - look at all the stuff you have already, you don't really need to do much to make it a killer - stroke it out to 2.7, do the cams, chip, intake, exhaust and you've got yourself a cold blooded mofo. Which you could have for less than doing the silly stuff to the Eta, which is going to cost you more for the same thing. Capiche?

Not saying that you can't do it, or that if you can get it done cheaply you shouldn't, but the Eta was not a perfomance engine - this was not it's purpose, and thus will not respond as readily as a 325iS. Therefore, more money which could have gone further on a car that is the logical choice.

It is your money though. Do what you please. =)

I can't talk, I'm a mile upside down in this E21, and I'm trying to sell it.

--
KMFDMR

[nukeduster]

Originally Posted by KMFDMR

It is your money though. Do what you please. =)

I can't talk, I'm a mile upside down in this E21, and I'm trying to sell it.

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KMFDMR

I know what you mean.. being un-employed the last 2+ months, I'm cleaning up my e30 getting ready to sell her :/

Half finished, 12 grand into her.. probably end up getting 2-3 grand just to pay rent heh.

FTL.

[gotKRAUT]

Originally Posted by KMFDMR

Okay.. Well, this is a point I'd thought about myself, so thanks for bringing it up, gotKraut.

From a marketing perspective, when the eta engines were released, they were filling the gap that the diesels in the BMW range fill today. They were built to be low-revving (low wear), torquey, fuel efficient daily drivers.

What is possible to do to the eta to make it rev is irrelevant - why would you spend the money? By the time you get all the conversions done, and everything is sitting pretty, you may as well have sold the Eta, gone out and found yourself a slightly worn 325iS and had it's internals given a nice sprucing. Financially, it's backwards - if the Eta was meant to rev, BMW would have made it that way.

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KMFDMR

as i stated before, i was mearly answering the question how, not is it worth it...

again, everyone is completely miss understanding the purpose of this thread