stage 2+ cone filters and maf

[Mr Whippy]

You can get a differential pressure gauge for about £50, and it'd be useful for everything intake-side of the engine.

Then all you need to do is tap in to monitor pressures at different points and you can build a picture of what is good and bad as you tune. When you start to see bad results, then you can get in there change things and check the result.

That is good tuning, be it DIY or done by a manufacturer.



I'm just sceptical of changes made when the critical analysis of the part to be improved is basically "that looks crap"


Even if you just started with basic rules of thumb. Compressor intake will be X big. Due to X Y Z principle the throat at the other end needs to be X + 10%

I'm aiming for 200bhp at peak efficiency, the standard dimensions seem to be set for 100bhp at peak efficiency. That means I need double cross-section, or add 30% to my intake diameter... blah blah blah.

Optimum pipe radius to meet compressor if routing that way is 2x internal diameter at X flow, but we want 2 x X flow so the optimum bend is 3x internal diameter.


Even just some basic maths like that then I'd be thinking, yeah, they have got a shot at doing something worthwhile, they've got the numbers, seen why the standard one is not good, and by some basic rules of thumb a change might get them 5% more efficiency at 150bhp, and get them another 7-8bhp for their effort!



We all know intercoolers are better than none full stop, so we do them. We all know the benefits of bigger pumps, better turbos. They are all specified, rated, and well understood.

But a pipe like that isn't, so to do a good job of it you need to invest more time than simply finding a picture and saying "that is crap looking"


Dave

[Ruan]

So unless we spend 5 years reinventing the wheel, don't bother tuning?

It's quite evident that Peugeot decided to adjust that pipe for higher powered models... Peugeot are VERY good at making compromises - that pipe as you say is probably "just enough, no more"... Perfect - but that's for 90hp... You can easily remove any restriction and as long as you've got a GOOD cold air feed, there's NO reason you shouldn't gain power, 700hp Turbocharged engines aren't using 306 HDi inlet pipes because they're so especially well engineered with their constantly changing movement.. Nor are Top Fuel dragsters...

I like the whole theory of test and see what's going on, but if you carried on doing that, you'll end up spending SO much money, then yes, you may as well buy a "better" car...

Or you could replace with a pipe that you know will allow enough air through, a good cold air feed, monitor your IATs and know you're fine for lots of power...

When tuning CHEAP cars, you sometimes just have to replace parts that you know will do the job perfectly well, otherwise as you push the power up, the parts that were once good for "stage 1" power, are no longer any good, so you end up overrating...

[Mr Whippy]

Why would you want a cold air feed when the HDi already has a ram air cold air feed? IAT's on the HDi are always at ambient or just 1 or 2 deg higher even in the height of summer.
It also has a ram air system which means that even though it's not a cool looking cone filter, it probably has less overall restriction post-cone in normal driving conditions than NO filter at all.

MAF is small, but you'd want to check a 123d or something with 2.0 and a lot of bhp and see how big their MAF is. If it's the same size then that is a good indicator that isn't a problem.

MAF on the HDi should be good for metering nicely to 180bhp at 4000rpm, and if you simply run a bit leaner at peak and have a dip to stoich (as an example), then 200bhp and nice clean running should easily be possible.


I'd say the biggest single cost to a HDi intake is the gauss on the MAF (not really needed if you are happy to run a perfectly good paper filter imo), and that weird bendy flexy pipe just after the MAF which probably causes a lot of turbulent flow too.

After that I'd say it's all good again right to the compressor, which is where your biggest single 'intake' bottle neck right up to about 200bhp sits... maybe even 250bhp, who knows


I agree, too much testing and you will spend a lot of money and maybe get not very far. There is a compromise.

But if you don't even know what you have and why it has merits before you start hacking it up there is every chance you will spend money and have a compromised car, which is just as bad as spending money and having tested a lot and not made any changes hehe.

Chances are that even if the HDi90 compressor feed is only 'good' to 120bhp or something, you won't suffer from it's issues from a cost effectiveness point of view till 180bhp+ any way... and even at that point you might be hard pressed to spend £200 or so making/fitting one vs the cost of some other mod that you know will be a better idea at that level.


It is all about the efficiencies, you don't want to run over-rated on too many things. But until you know which things are out of efficient range it's hard to justify spending money on a hunch for most people.
Most people ARE tuning a cheap car and want to do it cheaply, so £££ on a hunch inefficiency vs a known power boosting mod is a hard call I guess.

If someone said a new off the shelf £150 replacement pipe added 0% at 90bhp and 20% at 200bhp, then you'd buy one after stage 2 without a doubt.

If it were £150 and 5% at 200bhp, would you bother?

Dave

[Poodle]

I couldn't give a shit whether the cone filter looks or sounds cool, i'm interested because it can allegedly flow more than a standard paper filter. I know Jonny, he's not some boyzieee who wants sick induction noise innit or mad bhpss bruv, he's an intelligent bloke with an objective way of viewing new mods, so i trust his judgement. I'm not saying that automatically makes him right, but it saves me weeks of work doing my own testing for something that's not going to affect my figures by more than a couple of percent either way, as such i'm willing to take the risk, especially as it will help make the other, more expensive mods easier and cheaper to implement. Plus im not trying to create the perfect hdi bhp monster, just something thats great fun to drive, but still does the mpgs.

Have you ever tested the maf? How much of a difference is there with and without the gauze? I take that's why you think the maf is a significant restriction to flow?

[Jonny81191]

It also has a ram air system which means that even though it's not a cool looking cone filter,

Couldn't care less what it looks like, All I can go on is how the engine feels to drive, and at the moment the cone feels like it flows more.


I'd say the biggest single cost to a HDi intake is the gauss on the MAF (not really needed if you are happy to run a perfectly good paper filter imo), and that weird bendy flexy pipe just after the MAF which probably causes a lot of turbulent flow too.

I assume you've ran tests on the flow effect of the gauze? How much of a restriction did it impose? I'd have thought it wasn't that much on an issue, Peugeot wouldn't have fitted it otherwise...

And the turbulence from the flexi pipe probably makes no difference, as it'll have been designed with optimum flow in mind. A 90 BHP engine only needs as much air as a 150-200 BHP engine, does it not?

Sorry mate but I feel you're making a lot of noise about the air intake system, with no proof that it's good for big flow. As we have (at the moment) nothing to go by, all we can do is fit what we KNOW will flow enough air (big cone and large diameter piping), then go and see if it makes power. I'll try the options out on a dyno at some point, and if the results show I'm wrong, I'll happily eat my words. But for the sake of a few quid, I'd rather run what I think will work for now.

Peace.

[Mr Whippy]

I've not run any tests, that is why I leave it ALL standard. I've seen specific tests of this intake system though, and done lots of IAT logging to know that power gains are non-existent up to 150bhp, and with IAT/ram air effect you may possibly degrade those features if you mod.

From the piles of books and testing I have seen of different intake systems, then that is an area (gauze and concertina piping) where I'd look for turbulence and reduced flow efficiency.

Gauze is there to protect the MAF, just as the air filter is there to protect the engine. When they were new a new MAF might have been very expensive, I'm not sure. Right now with scrap yards full of them I'd be inclined to dump the gauze and smooth the concertina pipe. Easy to test the pressure drop over that run too.

But before I'd do anything I'd simply check the pressure just before that bend at the compressor inlet at normal road speeds. If it's anywhere above positive pressure with a standard intake (which I have a strong feeling it is from lots of reading about intake system designs and how the 306 HDi one works), then I'd say that anything you do will not make a difference.



Remember K&N and the like marketed their products when everything had a pancake filter and carbs, and petrol was 25p a litre and efficiency and emissions were not really a big factor.
I remember sticking a big K&N on a carb 2.0 4 pot 8v petrol and it felt a lot better vs the pancake filters 1 inch inlet haha! An inlet that fed off engine bay air via a crappy tin foil pipe that stuck a shroud over the exhaust manifold!
So this K&N which just sucked in normal under-bonnet air was amazing!

Then come the 90's, cat converters, ECU control, CR injection systems, a drive for low emissions and massive efficiency. Intake systems were suddenly designed with at least some effort, and suddenly things like K&N's and the like lost a lot of their market.

They soon started making panel replacements because a cone was worse than a panel which ran on the forced air intakes and cool air feeds etc.

But then panels were pointless too, the only real selling point was it was re-usable...



I'm happy for people to spend money on mods in the hope they add power/efficiency. Just giving my 2p on the system we have in the 306 HDi out of the box.

Yes, if you plan to upgrade to 250bhp, then that back pipe might be a bit crap. I don't doubt that. But until you get over 200bhp I'd concentrate on doing the important stuff right and make sure you put the funds there, because there is nothing worse than aiming for 200bhp+ and skimping on the important fundamentals.
Pump/injectors/turbo are essential for reliable high power tuning.

It's just gutting to see people splashing out on cams and engine balancing and stuff early on because their aim is 200bhp, but then run out of money and end up with a buggered turbo or HP pump and end up abandoning the project before they even get going

Dave

[Ruan]

Were not on about cams, lightening and balancing here, were on about an intake pipe...

Lightening and balancing are not detrimental to power, inlet piping is, it will also f*ck turbos if they are placing vacuum on the inlet pipe as the thrust bearing is being yanked the wrong way...

I've seen.2.5" pipes sucked in by turbos in the past...

[Mr Whippy]

Were not on about cams, lightening and balancing here, were on about an intake pipe...

Lightening and balancing are not detrimental to power, inlet piping is, it will also f*ck turbos if they are placing vacuum on the inlet pipe as the thrust bearing is being yanked the wrong way...

I've seen.2.5" pipes sucked in by turbos in the past...

I know, but the principle is the same.

Spending money on stuff you don't need means no money for stuff you DO need if you want to make more power.

If there is vacuum on the inlet pipe to that degree that it collapses the intake pipe, then you must have some serious vacuum and simply having a pressure take-off (like the nipples you put in the HDi elbow intake manifold union) would be all it'd take to assess the intake restriction.

I take it the 2.5" inlet wasn't aluminium but was actually silicone or something?


In any event, checking simple figures like pressure drop is easy and makes sure your inlet IS good if it needs changing, and makes sure you don't waste money if it DOESN'T need changing.

It also makes sure if you do mod and it works out worse you will know, or if you mod it and it's not much better, you will know.


Since so many people are desperate to buy shiny metal pipes I might just make some. £150 each for upgraded rear down pipes. Up to 10% gain in power!

Dave

[Jonny81191]

Ok maybe I need to phrase this differently. I'll fit an enclosed filter with a 3 inch pipe running to the turbo. It won't have any restrictive narrowing and there will be minimal bends of the largest possible radius. I will feed it from the standard cold feed and will use the porous pipe as is also standard.

That will be better than standard. Can't not be can it?

[Poodle]

The basis of this thread is for those who are aiming beyond the current "stage 2", therefore we need to look at the whole system. As you say, that pipe is very well designed for running X cfm of air to a compressor inlet Y mm across to produce 90bhp. By the same token what that pipe is definitely not designed for is passing 3X cfm of air to a compressor inlet Y+10 mm across to produce Z bhp. With different turbos being fitted it becomes daft to hold on the original pipe, purely because of difficulties with fitment and space constraints if nothing else.

I think the bit where i said i don't care about looks or shiny or noise got missed, so here it is again. Dave, we're intelligent adults, please stop treating us as you would kids with toys. Constructive conversation appears to have come to a close already tbh, but it would be good if we could resume discussing why the maf is a restriction and how to improve it.

[Toms306]

Back to the maf....


Dave probably has got a point about the mesh. It's there to smooth flow over the sensor, but just looking at it I reckon you're losing around 20% of the intake area there....

[Ruan]

So sack off the MAF sensor?

Or get a bigger one?

I know for a fact that the Boxer 2.8HDi uses a 1000kg/h sensor, which is EDC15, so you can just yoink the MAF Linearisation table straight out the map..

Even if it's not physically bigger, it'll give you greater range for higher powered cars, you MIGHT AS WELL get the bigger sensor, just like the 1800bar FRPS...

[Just Sean]

Finally a sensible answer thats relavent!

Thanks Ruan

[Mr Whippy]

The basis of this thread is for those who are aiming beyond the current "stage 2", therefore we need to look at the whole system. As you say, that pipe is very well designed for running X cfm of air to a compressor inlet Y mm across to produce 90bhp. By the same token what that pipe is definitely not designed for is passing 3X cfm of air to a compressor inlet Y+10 mm across to produce Z bhp. With different turbos being fitted it becomes daft to hold on the original pipe, purely because of difficulties with fitment and space constraints if nothing else.

I think the bit where i said i don't care about looks or shiny or noise got missed, so here it is again. Dave, we're intelligent adults, please stop treating us as you would kids with toys. Constructive conversation appears to have come to a close already tbh, but it would be good if we could resume discussing why the maf is a restriction and how to improve it.

You said it, we need to LOOK at the whole system.

You can't just arbitrarily say something is crap.
The WHOLE engine was designed for 90bhp by the logic of saying that pipe was designed for 90bhp, but as I've said numerous times it's about finding the inefficiencies that are both cheap and easy to overcome first.


We find even at stage 2 that the whole intake box/filter changes nothing vs standard if totally removed on a 150bhp tuned HDi!

That says to me that the intake system is well capable of running beyond design spec of 90bhp (remember the HDi90 is only engine in 306, so the airbox was only made for a 90bhp rating)

So right away we see a key part that people 'upgrade' for improved performance is actually perfectly happy at 75% extra air-flow!
What other parts might be happy to work at 75% extra with NO cost at all?

Why spend money replacing these if there are other things that are both cheaper and more inefficient to go chase down?



So why suddenly is the pipe that runs down the back enemy number one?

There is nothing to support it being bad except presumption because it looks like it should be crap.

Remember Pete had 205bhp from his HDi with that pipe and a VNT turbo. He did use the 2.8 HDi MAF though to make sure he could get good metering of air out to way into the mid 200bhp range.

So right now we know standard intake, MAF and back pipe should get you to near 200bhp without issues. Yes they may be starting to hit about 100% like the MAF, and if you can get an upgraded one on the way to 250bhp, go for it!



There is nothing wrong with the MAF fundamentally. You can flow a LOT of air through a small restriction. Those Lemans car diesels run 40mm or so and have 600bhp+!

The grating might aid superior air flow metering, so removing it might reduce intake restriction but worsen metering accuracy.

I think even the bigger 2.8 MAF has the same fundamental dimensions, just rated higher on metering capability... so adding one won't do anything except give you good metering at 250bhp tops.


If they can meter for 250bhp, then they can flow for it, and if that diameter intake can flow for it, then the pipe leading from it is best kept small to keep intake velocity high and not cause a pressure drop through an expansion.

Depending on compressor inlet size that might mean the pipe needs to step up or down in size at some point.



There is lots to consider and it's not just a case of making a 3" pipe that is smooth.

If your turbo is 3" compressor inlet great, but it probably isn't. So how do you smoothly transition to the compressor inlet size?

If your MAF is 2" internal diameter say then you need to taper smoothly all the way from MAF to the compressor inlet to get optimum flow... I have no idea how you go about doing that.


The easiest solution is to make a pipe your compressor inlet size and run it that diameter all the way to the air sensor, or run MAP or whatever...

But that all seems crazy expensive considering that it probably won't cost you anything.


What spec intake does the 123d BMW run to it's first turbo?

It's 2.0 capacity, revs to about 4500-5000rpm, and is super modern and remaps to 250bhp.
That is a great reference point for what sizes things need to be and so on.


Dave

[Arron]

All an interesting read.... whilst we are on the subject of Mafs..is the 2.8hdi maf plug and play, as in no need to map in or cross wires?

Im sure the hks mushroom I use has made a difference... especially initial throttle response... but I'm on my 3rd maf now. I know cone filters are terrible for heat soak in summer but its simply a case of you can't have it all IMO. On mine The inlet is 3 inch with a silicone reducer onto the maf. I must admit that pipe going to the Turbo does look restrictive but I'm only running a stock gt15 so I doubt that the Turbo will need anymore air/flow than that pipe gives

[Poodle]

That 2.8HDi maf sounds ideal, will keep an eye out in my local scrappy.

Haha it's not enemy number one, just another minor thing getting in the way of other developments. Even if I don't change it for performance reasons, i almost certainly will for practicality, simplicity and expense reasons lol. Not until I'm chasing stage 3 though, as you say, there's little point doing it before that. Tbh i was thinking of finding an alternative route for the inlet piping, but that's another story.

I think I can get maf flow readings on PP, will have to have a play with the grating some time and see if can spot any differences.

Bearing in mind Sean doesn't have a VNT, would there be any particular benefits to changing to a map sensor?

Off-topic, but I thought the intakes on the lemans cars were restricted by competition rules..?

[Mr Whippy]

Yes, the intakes on Lemans are for restrictions, but it just shows how much air can be sucked through them still! And if that is 'sucking' rather than being rammed through, the intake vacuum will be high, so that obviously isn't always a bad thing?!

As said, fluid dynamics isn't my strong area really, lots of weird counter-intuitive stuff goes on so what you see or imagine as being right or logical might not be the case.


MAP sensor seems over-kill in my view. MAF sensor is more intuitive as it's logging the actual air mass pre-turbo. Not sure why MAP might be more preferable except on engines that will be making MEGA power and a MAF is just a restriction you can do without (ie, tractor pulling maybe?)

I was at ASI at the NEC yesterday and lots of the intake people these days seem to have those MAF sensors that slide into the pipe through a mounting hole. Seems a better approach in my view. The OEM's do that now but not always on the best pipes.
Also the filter people still use silly cones without proper ram air feeds, but I guess they need a USP and to stand out against OEM, otherwise why would people buy?
I also noticed they had the most flash stands with their products placed like crown jewels haha... even my wife was looking saying maybe I should get a K&N haha!
Marketing over substance? Hmmmm...


2.8 HDi maf does indeed sound good. But those slide in MAF seem better. Then you can run any size pipe and mount an adaptor plate for the MAF. Only issue would be calibrating, BUT, I think you could do that by running it in the car alongside a 2.8 MAF (upstream maybe), and log values from both and then plot the new calibration hehe

Oooor, get the calibration data from a car that uses that type of sensor with a similar pipe diameter to the one you want to use...




Aaron, the sensor will probably need a tweaked map... you won't benefit at all from it unless you are up over 185bhp, but in theory you can probably run standard sensor with "ok" metering to 200bhp.

I think any air-filter as we have seen, is no different to OEM. As said, at 150bhp on a 206 HDi FMIC, a range of filters from standard, cones, etc etc, all the way to no filter at all, made no difference at all really. All dynos were within a few bhp of each other.

Dave