The unsung hero.... the mighty log

[Lubed 55]

Thougt i would start a fresh on this topic to get some ideas out there.How many people out there think the 335i has a fairly impressive power output?.... and it runs a couple of little logs? go figure?

Edited July 24, 2008 by streetmagic

[Huttey 0]

Well that didn't work

[Lubed 55]

If some clever person on here can goggle search images for ( 335i engine ) and post the picture of the turbo set up that would be good of them seeing as i cant seem to manage that simple task at the moment

[CamB 48]

This is a pic:

I suspect those semi-equal length short manifolds flow pretty well - they merge nicely into the collector, and they're quite little turbos.

The argument in the other thread was about a poorly designed log which might/would restrict top end power.

If I was sticking a turbo on an M3, I'd want to make sure it could still rev.

It's a bit debateable whether the one going on my M10 (which is free flowing, 4 into 1, but un-equal length) is going to offer me much extra, but I bought one like that anyway...

I remember reading this a while back - basically says the log (a nice one - not that sack of crap DA motorsports one) spooled the turbo fairly quickly but choked the top end:

http://www.full-race.com/articles/Bseriestest_writeup.pdf

Yes, I know its a honda engine.

Edited July 24, 2008 by CamB

[Gus 5]

the 335i output aint that great...3.0 L turbo making 300hp? an increase of 60hp or so over a stock 3.0?

imagine what it could do with a nice free manifold and a large turbo!!

I really like the TCD M20 log manifold..good for 400 hp if I remember rightly?

[topcat 11]

looks tidy,dont tink i can copy it.

as for power,i wasnt impressed.had the privalige of sitting on the rear end of one of those 335's.

he couldnt do much to shake me off.

wonder what he was thinking,cause he kept looking in the rear view

[Lubed 55]

Yeah thats the picture thanks... if you look closely you can see cylinders 1 and 3 plus 4and 6 point very close to each other,also on cylinders 2 and 5 the runners are nearly half the length of 1,3,4,6. The debate im trying to put out there is that the turbo itself is going to be the biggest restriction in the system due to the exhuasts gasses having to push that turbine wheel around and around against the resistance of the compressor wheel spinning up all the boost

[Gus 5]

^^^^ well, duh...kinda obvious really isnt it?

what point are you trying to make?

[Lubed 55]

^^^^ well, duh...kinda obvious really isnt it?

what point are you trying to make?

Congratulations you get it but i think alot of people may not . The point im making is that the manifold design is not all that important as its cracked up to be as its still upstream of the bottle neck.As for the 335i making 300hp you have to keep in mind that it only runs 8.5 - 9 pounds boost in standard trim for longevity reasons and to also not show up its big brother... imagine giving those little turbos on those little logs a little tweak

[Mike 1]

The point im making is that the manifold design is not all that important as its cracked up to be

Only up to a certain point.

The manifold design plays a huge part in the power delivery of the motor. Logs are fine for a quick spooling street car with a limited top end. Anyone wanting to make serious power probably wont be using a log style manifold. Yes the turbo is a bottle neck, especially if its undersized, but the manifold still has a huge effect on the turbos response and power potential. Then theres thing like split pulse designs, which are very tricky to do with a log style manifold. Theres more to turbo exhaust systems than just flow.

I dont think there'd be a huge amount left in those turbos on the 335i, they are pretty tiny - designed for instant response. Surely you'd agree that a tubular mani with big single turbo is capable of much higher outputs than those little butt plugs.

Edited July 24, 2008 by Mike

[Gus 5]

Why do you think you are so right? do you have any facts at all to back up what you are saying?

I can see a little of the logic you are using but it doesnt have application to what actually happens.

Mike's right - the manifold plays a large part in the action of the turbo

Excuse me for pointing out the obvious, but are you sure those 335i manifolds fit into the log description? I am not 100% sure

In case you haven't noticed, no-one here thinks a log manifold is crap. they can be great. however there are better solutions out there for power, end of. log-lover.

[pjay 8]

streetmagic fails

[CamB 48]

imagine giving those little turbos on those little logs a little tweak

I don't know what you mean?

You could turn up the boost, but that won't give a huge amount of extra poewr but will - with little turbos - create a lot of heat as the turbos will be outside their efficiency.

There are two issues here:

1) Whether a log is any good - it can be, if well designed, for small(ish) turbo(s) and lowish power outputs. They are less appropriate for top end power, in particular on engines that rev and make good power at high revs (ie, any performance naturally aspirated engine converted to turbo), and for bigger turbos.

2) Whether the picture posted in the other thread is any good. It's not. The DA manifold is a crap design. It removes the only benefit a log offers - quicker spool due to short runners - through a crap design with sharp corners and a larger plenum area.

Maybe this whole argument is due to you having different views on what is "good" from a turbo system. If low boost and relatively low power is the goal, a log probably does the job.

[Andrew 30]

Maybe this whole argument is due to you having different views on what is "good" from a turbo system. If low boost and relatively low power is the goal, a log probably does the job.

I'm sure the 335 could do better with as you say larger turbos. I wouldn't say it had a log manifold.

The log works fine on the 1.8ltr 300hp e30. Granted it runs 18psi.

[Gus 5]

I'm sure the 335 could do better with as you say larger turbos. I wouldn't say it had a log manifold.

The log works fine on the 1.8ltr 300hp e30. Granted it runs 18psi.

v true...doesnt mean it couldnt be better.

the Hartge 335 does 380 hp which aint bad..imagine what that engine could do let loose!

[Apex 693]

Thougt i would start a fresh on this topic to get some ideas out there.How many people out there think the 335i has a fairly impressive power output?.... and it runs a couple of little logs? go figure?

It puts out good usable power and torque that can be accessed from anywhere in the rev range, the engine is fantastic but the overall power is not that impressive, it is an efficiency engine before it is a performance engine.

The Toyota 3.0Ltr Twin Turbo 2JZ-GTE had more power 15 years ago and just look at what they can be tweaked too, far beyond the BMW engine.

[E30 325i Rag-Top 2956]

the 335i output aint that great...3.0 L turbo making 300hp? an increase of 60hp or so over a stock 3.0?

imagine what it could do with a nice free manifold and a large turbo!!

Don't read too much into the stock production figures, the power would be severly wound back to make sure the engine is rugged enough to survive any punishment in service. There's a 3-year unlimited Km's warranty to get through.

One of the biggest frustrations in automotive design is to have to turn things down to reduce the risk of failure and warranty claims to satisfy the bean counters. There would be heaps more power available, even from ECU mapping alone, before you have to worry about changing the hardware, the good old "safety factor" coming into play.

When Cosworth worked on the original Sierra their target was 100bhp / litre the only problem they had was keeping the figure LOW enough to satisfy the risk managers - one for engine reliability (even stock 2ltr cossie good for 300+ bhp and reliable for years) and insurance risk. It's still the same today, which is why people like to tune their cars and all the aftermarket boys are out their - shame it voids the manufacturer warranty!

[Apex 693]

Yea they just get the tap out and turn it back.

[Lubed 55]

Why do you think you are so right? do you have any facts at all to back up what you are saying?

I can see a little of the logic you are using but it doesnt have application to what actually happens.

Mike's right - the manifold plays a large part in the action of the turbo

Excuse me for pointing out the obvious, but are you sure those 335i manifolds fit into the log description? I am not 100% sure

In case you haven't noticed, no-one here thinks a log manifold is crap. they can be great. however there are better solutions out there for power, end of. log-lover.

Looks like a few cages have been rattled over this thread.... I dont as you have put it " think I am so right" Im mearly stating a fact based on knowledge from more than a few of years in the motor trade.

I fully agree that for maximum power a well tuned manifold is required... thats not the original point that i was making but you have to remeber we are mostly talking about R/H/D street cars for which a log is more than suitable for pumping out some fairly serious numbers.

If you read back through the previous thread there are some negative views on the log.Im not the enemy... just another guy with a common interest in BMW who enjoys a good debate.

[Lubed 55]

streetmagic fails

As for this guy... what a hater.It appears he does not have the bottle to make his own thoughts on this topic known.

[320guy 0]

Congratulations you get it but i think alot of people may not . The point im making is that the manifold design is not all that important as its cracked up to be as its still upstream of the bottle neck.As for the 335i making 300hp you have to keep in mind that it only runs 8.5 - 9 pounds boost in standard trim for longevity reasons and to also not show up its big brother... imagine giving those little turbos on those little logs a little tweak

Its not all about a free flowing exhaust to the turbo to help the engine breathe better. Its about the manifold preserving the exhaust energy to help spool the turbo.

Well designed log manifolds can be good (TCD log manifold for example, good for 400HP), but the DA manifold is crap because it introduces more turbulence and bends than is needed + the big chamber all the runners go into reduce exhaust gas velocity.

A individual runner manifold is even better as the exhaust gas pulses from other cylinders dont interfere with each other and it is possible to run split entry turbos to their potential (can be done with two log manifolds on a 6 cyl aswell though).

[320guy 0]

There were some simulations done on the DA manifold, although not 100% accurate, it does show it is a pretty bad design. Not that you need a simulation to work that out, you can tell by just looking at it.

[elmarco 56]

Don't read too much into the stock production figures, the power would be severly wound back to make sure the engine is rugged enough to survive any punishment in service. There's a 3-year unlimited Km's warranty to get through.

One of the biggest frustrations in automotive design is to have to turn things down to reduce the risk of failure and warranty claims to satisfy the bean counters. There would be heaps more power available, even from ECU mapping alone, before you have to worry about changing the hardware, the good old "safety factor" coming into play.

When Cosworth worked on the original Sierra their target was 100bhp / litre the only problem they had was keeping the figure LOW enough to satisfy the risk managers - one for engine reliability (even stock 2ltr cossie good for 300+ bhp and reliable for years) and insurance risk. It's still the same today, which is why people like to tune their cars and all the aftermarket boys are out their - shame it voids the manufacturer warranty!

+1 Jon

Precisely why the car companies take so long to design and validate (as we both know - PFMEAs up to the eyeballs!!). Can you imagine the liability if 100,000 units needed an engine replacement? The cost (to BMW - not what you and I would pay) would be close to half a billion $....

Oh and don't forget the emissions and corporate average fuel economy laws.... I have no doubt that the white coats in Munich could realise much more from this motor, but have solid (germanic) reasons to leave it right where it is.