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Use of ribbed hoses and its adverse effects on the intake air flow - Page 2 - Induction/Turbo/Chargecooler/Manifold/Exhaust - The Lotus Forums #ForTheOwners Jump to content


Use of ribbed hoses and its adverse effects on the intake air flow


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Conversion to the "Ram Air" yielded power improvements on the dyno. Not "smooth bore " duct (yet), but pretty impressive with overall minimal cost. For dyno plot see  http://www.lotustalk.com/forums/f164/ram-air-mod-dyno-d-89se-403865/#post5323929

Edited by MrDangerUS
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Whatever gains are made, they probably aren't going to be noticeable in the real world for most of us. A 5% increase in power for example, doesn't equate to 5% more top speed or 5% off the 0-60 time, and most of us rarely us our cars at full power. @Changes did make a massive difference, with 412hp (IIRC) over the original 264hp, but for most of us, the things that hopefully give an extra few hp (rather than lose any) are more about the sound /tone etc.

So, if a nice smooth, free-flowing induction gives a nicer engine note, then it's probably worth it for that alone, rather than any reduction in acceleration times etc.

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  • 2 months later...

I take it a Little different. For me, it's more the sum of many small Things that create a collective effect, thereby making the engine breathe and run better.

Ram air mod, a filter, cam adjustment, free flow cat, exhaust, tubular manifold etc, all make up for small increments. But the gain will only really show, once they Work together all of them.

Very interesting measurement, John. I'll measure mine a Little later this year, I hope. Just did the ram air mod yesterday.

Kind regards,

Jacques.

Nobody does it better - than Lotus ;)

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  • 2 weeks later...

Jacques,

I'm in total agreement w/you!

I call it the "SUM of incremental improvements" or "engineering synergy". Well thought out modifications should work together contributing toward a cumulative improvement.

I see, you have been slaloming cleverly around some silly government regulations with a great result!

Congratulations!

John

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Cheers, and I will dyno measure it once more, asap as the ram air mod and the correct 12 mm wider intake hose is now in place. I tried to install the Sport300 intake hose with as Little bending as possible. More like one smooth curve. That turbo surely can gulp some more air into it ;)

I will take Dave and you Guys Work on the intake flow up in the Winter, as I have the 1" Spacer "ring" and another complete intake plenum (a Lotus test one) to fiddle with later.

More later.

Kind regards,

Jacques.

Nobody does it better - than Lotus ;)

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  • 5 months later...

In addition to the smooth bore duct, increasing the air inlet port by 40% is a prudent step. This engine desperately wants to breathe freely.

Imagine running Marathon wearing a gas mask?  LOL

Also, a director vane was added inside of the 90 deg elbow. Any 90+deg bends are v. bad for the flow.

 

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  • 2 months later...

If you're still thinking that the smooth bore duct is inferior, when compared to to the "elephant trunk" dryer hose,

can you explain, please, why the airplane fuselages or exhaust  pipes are not ribbed ?

Just asking...

 

Also, see this  http://www.lotustalk.com/forums/f164/ram-air-mod-dyno-d-89se-403865/

..

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So why use a 90deg bend and not two 45deg bends?

I would think with the way the trunking goes now, you would be able to get there with the 45deg bends. No?

All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

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38 minutes ago, ramjet said:

So why use a 90deg bend and not two 45deg bends?

Because the resultant loses would be the same as the change in direction is the same.

I.E if you loose 50% with one 90 degree bend but loose only 25% with a 45 degree bend but you have two of them. :thumbup:

Cheers,

John W

http://jonwatkins.co.uk

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Fair enough Jon. I was asking based on John D's comment of 90+ bends are bad for airflow. I just thought that 45deg would be less harsh and the air would be happier. Possibly no need for the internal addition to the bend which would be detrimental to the total airflow as well. Though minimally.

All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

For forum issues, please contact one of us Moderators.

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11 hours ago, Buddsy said:

I polished my head intake and exhaust castings then learnt that the rough castings provide an air buffer which allows the air in the centre to move faster with less friction than a polished port...DOH!

I had read the same holds true with the ribbed turbo air intake pipe over a smoothed wall air intake pipe. 

I have to add I know nothing of the flow of gases but that was just something I had read on here a long time ago.

 

buddsy

Yes ,  But not as simple as just that.   The air buffer you refer to is the laminar boundary , sub or  viscous layer and its thickness or layer levels is the influencing factor..  You will find the velocity of the center flow moves quicker in ribbed duct for the same volume requirement, because the thickness of the laminar layers narrowing the effective size of the laminar stream,  hence it has to move faster to achieve the required volume..  The same size duct with a smooth wall will have much smaller sub / viscous layer, so the center laminar stream is larger producing less velocity for the matching volume requirement.   

On pre turbo, or N/A engine up to plenum , the velocity is not the issue ,it the volume with least resistance.  So larger smooth ducting with calibrated reduction where needed will out perform like for like ribbed hose hands down..  

As for head ports you refer to , well that follows the same thought but with added factors.. First the inlet. Up to just prior to fuel introduction point the lowest viscous layer you can get the better..  After that its a balancing act with port size and velocity for the given VE of the engine.  You need a boundary layer to prevent the fuel molecules from beading on the port wall . But you also need a given velocity to keep them in suspension with the laminar flow.  There is also the factor that you need an optimum velocity across the valve to maximize cylinder filling.   This all brings us to the fact that bigger and smooth inlet ports don't always work, too big and the velocity will drop , along with performance.. So rough finish in larger ports can actually be needed .. within reason (to much to list..)   However when the VE of the engine is all increased the balance of a larger inlet port with a reduced laminar layer providing the optimum velocity produces the engines full potential..      On the exhaust side , more polished the better, get those gasses gone.. 

Air flow is a science in itself , also one of the major parts of engine tuning,  Most of it is common sense, but understanding the science is what makes the difference.. 

hope that helps. 

D        

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  • 3 months later...

For those of you wanting the benefits of ram air, this is probably the best budget non-invasive solution yet..  Simple, quick, cheap and effective..  ' Four reasons which will probably get your interest'.   

Another point which can also be cheap is the intake grill ..  On John's photo you will see he still has the std intake gauze grill, this has a 30-35% flow restriction factor due to the tight weave ....  If you change to a much larger grill with circa 12mm holes then the flow restrictions are reduced to minimal percentile.  The wire gauge on said grill should also be thin..  A suitable source for this is a piece of the grill found within the sound inhibiting box under the o\s wheel arch which will no longer be in use... Ideal for the job and F.O.C......  

Also remember max flow air filter at all times is needed to capitalise on these type of mods ....        

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Yes Dave, you're right, but I have run out of time.  I had to finish all changes by May 25 to be able to attend the first show of this season.

I'm planning to replace the CAI intake mesh this winter, together with some other improvements. Already, the car is running like a scalded Ape!

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1 hour ago, MrDangerUS said:

Already, the car is running like a scalded Ape!

A certain Lotus addict now scouring eBay :thumbup:

Only here once

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I’ve done this very modification tonight. I can confirm it does make a noticeable difference in throttle response.

elephants trunk must be the next

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May I ask what the part number of the k-n filter you are using? I've re routed my elephant trunk over the winter and I'm thinking about this smooth bore mod.

'89 Esprit, '77 Elite 503, '72 MGB, '95 XJ12, '10 Mini Cooper, '67 Imperial, '78 New Yorker, '76 Town & Country '73 Cessna 150

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3 hours ago, 89esprit said:

May I ask what the part number of the k-n filter you are using? I've re routed my elephant trunk over the winter and I'm thinking about this smooth bore mod.

 

2 hours ago, Barrykearley said:

I’m using a standard paper filter. The partnumber is in the cross reference section on here though

If you lads want to get the best from this , Go for the highest flow (top quality) air filter you can get..   The aim is to get the negative pressure between the air filter and the compressor as low as possible .  This will reduce the scavenging load on said compressor so reducing MAT caused by that.   It then in turn puts less load on the charge cooler allowing it to be more efficient at keeping the charge as low in temp as possible so improving VE , result is more power..     So improving the elephant trunk is just as important........... Always remember an engines performance is the sum of its parts,  they are all interlinked , to step up you must address the most restrictive part at what ever stage you are at first.  Anything else will not realise its full potential and confuse results until that primary choke is addressed ..             

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Awesome, Thanks!

'89 Esprit, '77 Elite 503, '72 MGB, '95 XJ12, '10 Mini Cooper, '67 Imperial, '78 New Yorker, '76 Town & Country '73 Cessna 150

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