Equal length inlet tracts rv8 twin turbo

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Re: Equal length inlet tracts rv8 twin turbo

Post by DaveEFI » Fri Mar 09, 2018 9:51 am

The length and size of the inlet tract affects what is known as the ram effect. Think of a trombone - as you move the slide, the note changes. The note the trombone makes occurs at the resonant frequency. At resonance, air flows much easier. In an engine, this gives a peak of torque at resonance, ie a particular RPM. But of course the peak torque figure is determined by other things too.

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Re: Equal length inlet tracts rv8 twin turbo

Post by Twinturbotr7 » Sun Mar 11, 2018 9:41 am

Well From the research I've done on old posts on this forum blended bases on n/a engines seem to perform better than standard trumpets ,maybe not quite as well as act carbon trumpets but still a improvement I've never seen any tests done on a forced induction with a blended base?? but as I've learnt this week having equal length inlet tracks is pointless on forced induction motor , so can't imagine a blended base on FI motor wouldn't be any worse than on a normal motor , I've just sent my base off to get the final 8mm removed from it when I get back my inlet tracts will be 38mm shorter I've made the disision to set all my trumpets to the same height and set them all to 38mm heigh to compensate for the loss in inlet Tract length , therefore I will still have the same theoretical length inlet tracts as the blended base this coupled with the facts that I'm fitting 40mm id aluminium trumpets with lager bellmouths should all work out ok , well we will just have to see I will post a picture when I've finished my aluminium trumpets

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Re: Equal length inlet tracts rv8 twin turbo

Post by SuperV8 » Fri Mar 16, 2018 1:26 pm

Normally Aspirated engines have the pressure of the column of atmosphere above then to push air into them - why they make less power at altitude, less air above them, less pressure.
Forced induction motors have additional pressure from a pump to help push more air into them - similar to a NA engine running on a planet with higher air pressure, like on Jupiter (forget the composition of the air for this analogy!).
Any modification to help the air get in and out of either engine would in theory help make more power.
The fact is bolting on a supercharger or Turbo would usually make massively more power than fine tuning the inlet of a NA which means spending time/money trying to find another 5 or 10HP when you have just bolted on 100HP rather pointless.

I had the same thought, regarding the inlet trumpets. I also changed my inlet manifold from side entry to front entry to make my plumbing neater and more direct (centrifugally supercharged 4.6) and noticed how close the trumpets are the the roof of the manifold, also thought about blending the base but easiest thing for me was to just cut of the bottom portion of tube and re-fit the trumpets. I did however cut an equal amount of each tube so the inlet length remained roughly equal. The outer 4 trumpets are set slightly lower in the base.

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