Thread: Thinking about a custom manifold

Wow, that is a fine read my friend.



Dudeman

That thread is great. It is amazing how much work is put into something before you even start production.

I do a lot of testing and RnD but almost everything I do I test on the dyno. Nothing Beats real world results. I do test AND COMPARE a lot of parts on many cars and even try cross-testing parts between manufacturers and such.

I can say that I have had one intake manifold in particular that was partially designed using sold works and on the flow bench it had uneven flow from back to front.

I do have 2 other manifolds I'm currently building to test on the dyno. These arent anything crazy, but something that if they work out good, I can manufacture in a timely process and possibly for a reasonable price.

agreed! However from what i have found with the vvl engines because of the low lobes the low end losses (associated with headers and intakes) are not as drastic. Also i have noticed that because of the reverse tapper on the standard plenum there are actually some low end gains to be had, even if the manifold is not necessarily designed for low end power.

eg. look at corys dyno (in fact if someone can post it or link it that would be great). His runners are 6.5 inches long and a 2.2ltr plenum and i would say not ideal for the vvl engine, but a great improvement from stock. Still he gained low down power even with those short runners. I put this down to his runners not having a reverse tapper and therefore the air speed at lower rpm is more desirable.


The standard ve intake is an interesting piece....it will flow quite well by itself, but attach it to the head and watch the flow figure of that head drop.

donttazmebro - easy from a fabrication point of view...just the time involved equals dollars which a lot of people can no justify.
This style of plenum was used in the turbo era of formula one and the old rally days and still today with some "production car" engines in europe and japan...by far the best design which has been proven over and over again and will be used on my own car

ca18 bluebird - send me the link that would be great. totally agree, hence the reason why I would prefer to make a complete custom unit because reverse taper defeats the purpose. That being said, I would really like to understand why the factory down this, there is a reason for it and they are the ones with the millions to play with testing and development.
Just putting this out there, if the inlet flows so well it makes you wonder why people dont just keep the standard manifold pull the head off and do some decent porting, maybe some larger valves and remove the restriction ? It is all about effeciency and removing the bottleneck is the first place to start.

As far as the n1 manifold goes it was designed for a 86bore x68 stroke motor we are using it on an 86 bore x 86 stroke motor. The air coming into a 68 stroke motor isn't required to fill the cylinders as fast as the 86 stroke motor.

very basic but i would rather give you a quick idea as to why nissan designed it this way than try to over do it

Would that style benefit an N/A application for the sr20ve motor?

simple answer for a simple question, thanks

Kevin from Kelford was telling me last week that the reverse taper is due to the low intake velocity of the VE head. He said that normal tapered intake runner going the other way is only an advantage if the head you're putting it on already has good intake velocity and also advised me to use parallel runners & not tapered ones if I get a custom one made. The man builds some of the fastest engines in the world so I'll go with what he suggests.

Once we've worked out the correct RPM peak for my engine Ariel, I would certainly be keen for you to make a custom intake for me

The reverse taper serves several purposes for the factory. Everyone needs to remember that HP is not the only goal with these motors. They need to run great, make power but most importantly, these need to run CLEAN, EFFICIENT, and PASS EMISSIONS. The reverse taper does change the intake velocity, as well as with the air moving at a higher rate from the plenum into the runners, as it moves downward, it will "thin out" and slightly lose pressure which can help with the fuel atomization which helps with emissions. A lot of it has to do with air flow at partial throttle where the air moving through the intake manifold is at lower than atmospheric pressure. This is where the engine spends most of its time running.

dont care about emissions, i want powahhhhhh (well, torque technically)