Opinions regarding this intake 2

[hvychvy81]

This is an intake that is popular among the Neon owners... I dont believe that it is functional regarding performance gains. i have not personally personally performed this modification. I just wanted to see what kind of problems everyone saw with this setup. Please feel free to "Bash" it... I want all honest personal opinions.

thanks in advance, stephen

 

[hvychvy81]

My apologies, I forgot to include the link to the thread

http://forum.2gn.org/viewtopic.php?t=12037

 

[patprimmer]

If I understand it, it is made from the original aluminium runners glued into an ABS pipe.

It has to withstand turbo boost and under bonnet temperatures. ABS is not really strong enough nor temperature resistant, nor solvents resistant enough to do the job.

OEM plastic manifolds are normally made from Glass Filled Nylon 6.6 which is considerably more expensive and more difficult to process than ABS.

If ABS was suitable, OEM would use it and solve the problem of gluing the various components together.

Regards

eng-tips, by professional engineers for professional engineers
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[hvychvy81]

Well, actually its not an aluminum intake... the intake is plastic. Then they cut the runners down and jb weld the PVC pipe into that. Seems a little dangerous to me. And also, most of these gus are not intending to run any kind of forced induction in these homemade manifolds.

 

[patprimmer]

If the OEM is plastic, it will be Glass Filled Nylon 6.6.

Nylon is very difficult to glue.

The link says ABS, but you say PVC. These are different plastics with different properties. PVC is more common than ABS for pipe, but both are used and both respond well to solvent bonding to themselves, but not to nylon.

The manifold will be fragile and prone to cracks between the nylon and the PVC/ABS?

The different plastics will have very different reactions to temperature changes. ABS softens at about 100 to 110 deg C and PVC softens at about 90 deg C. under bonnet temperatures are more likely to peak at 130 or 140 deg C I would think.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[hvychvy81]

Good catch, I thibk I just assumed PVC since it is so common. Thanks for the info, I dont believe i thought of it from the stand point of the differences between the types of plastic.

 

[rpmag]

it constantly surprises me that some people think that a plastic/alloy log manifold will do better than the well tested production manifold. Do they think the original engineers are stupid or that they wasted their time and should have used some old waste pipe and glue!
I would be very surprised if this owner gained much in the way of performance even at one specific rpm.
The intake runners entering the plenum are not radiused. Plus sticking the ends out into the prevailing airflow is not wise. T'would be better if they joined in a similar manner to the stock manifold.

 

[GregLocock]

There's nothing wrong with a custom manifold... so long as you fit new cams and new fuel and new spark, and in this case a new red line.

But if you don't then I suspect the gains would be small, at best, and negative, typically.

Basic engine 101 says VE is good for economy, and torque, at a given rpm. OEMs like good economy, and performance, for no money. So, either the OEM engineers are thick as two short planks, or the VE has already been optimised. Most OEM engineers are only as thick as one short plank.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[kenre]

Greg, ive seen a few weired and wonderful attempts of backyarders attempting to better an engineers work.

Some of these make two short planks look like a computer!!

Ken

 

[rpmag]

I think a new manifold that switches to ITB's or a larger-different design plenum/runner combination for specific turbo application, e.g. for drag racing or an engine that is essentially redesigned and is being used for a different purpose is quite a valid modification.

 

[hvychvy81]

I would have to agree... I'm currently trying to find information regarding the tuning of ITB's. I'm not interested in foreced induction for my car at this time.

This intake design seemed so wrong in too many ways. I belive an all aluminum intake would be better for these kind of modifications.

Unfotunately I do not have any experience with welding aluminum, and do not wish to spend alot of money having someone else build an intake for me.

One of these days I will be able to fabricate what I need, but for the time being, I like to learn as much information as possible so that my "backyard" creations will add performance, rather than take it away.

Again, thanks everyone for the comments.

 

[patprimmer]

If you wish to make a tuned length high performance manifold, you will need to make it from metal or FRP.

Individual throttle bodies are very difficult to fabricate unless you have considerable skills and equipment.

An easier way is a similar design to many OEM designs that have individual runners feeding from a plenum, with one big throttle body on the plenum. That way you just buy a suitable sized throttle body from the wreckers. This costs a fraction of response time, but actually can make more power as the throttle body is a restriction that creates some turbulent flow. The inlet to the plenum is a less sensitive area re turbulent flow than is the manifold runner near the port in the cylinder head. This is at least partly because the restriction in each runner disrupts both the inflow flow and the pulse back from the closing valve.



Regards

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[hvychvy81]

With that in mind, what would be your opinions regarding a dual plane intake manifold? One that would use butterfly valves to close of air flow to the shorter runners during low rpm's and opening up at high rpm's?

This design has been used numerous times in OE form,,, but would there be better way to tune the butterfly time contrary to what the oem ecu is set to do? I know that rpm window switches (available in the aftermarket) can be used to control the motor that operates the inatke tract valves. Is there a formula used to calulate optimal dual plane intake manifold "actuation"? Or is it more or less just a trial and error on the dynomometer... -or cheaper- The butt dyno?

 

[patprimmer]

I think it requires calculations re length and cross sectional area of each runner to get a starting point close to what you want, then fine tuning on the dyno to get it just right. Some of the variables of tuned length are less predictable than others. The interface where the two air columns come together I would expect is one of those unpredictable areas.

A cheap dyno is a stretch of steep uphill open road where relative speed can be checked against landmarks. A bit rough but can indicate reasonable size gains and losses with some measure of magnitude.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[rpmag]

Fiat/Lancia tried a vacuum operated variable length manifold on the higher spec Lancia Thema's of the 80's. This level of tech is achieveable for a backyarder, but it is telling that it has roven problematic and many owners are converting to a non-variable manifold.
WRT ITB's you can of course use suitably sized OEM ITB's or motorbike ITB's, but not with a stock computer...and it gets expensive.
Should you wish to get an article on tuning you can email me at rpmagazine@optusnet.com.au and I will email you a copy of an article from the current issue of Race Magazine. The material comes from a MoTeC engineer about his own car and his experiences with it. It might help a little with some aspects.

 

[GregLocock]

http://us1.webpublications.com.au/static/images/articles/i27/2792_11mg.jpg

is a shot of our boroadband manifold. You can see the vacuum actuator, which turns 6 butterflies.

Cheers

Greg Locock

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