Equal length inlet tracts rv8 twin turbo

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DaveEFI
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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
Nck

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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.

Tom.
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Re: Equal length inlet tracts rv8 twin turbo

Post by Twinturbotr7 » Fri Mar 23, 2018 8:43 pm

SuperV8 wrote:
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.

Tom.

Hi tom think I've seen your front mounted throttle body, is your car the supercharged dax rush?
I've had my trumpet base back from the machinist, just chopping up my new alloy trumpets I'm using some I've bought from burton power ,some alloy ones off Webber 40's there a little bigger inside diameter 40mm of so going to port it out a bit ,I've been cutting down the trumpets to the correct height i think today I'm going for 38mm for the middle 4 and 23mm for the outer 4 that's the same ratio as the standard rover arrangement

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Re: Equal length inlet tracts rv8 twin turbo

Post by SuperV8 » Tue Mar 27, 2018 9:44 am

Hi tom think I've seen your front mounted throttle body, is your car the supercharged dax rush?
I've had my trumpet base back from the machinist, just chopping up my new alloy trumpets I'm using some I've bought from burton power ,some alloy ones off Webber 40's there a little bigger inside diameter 40mm of so going to port it out a bit ,I've been cutting down the trumpets to the correct height i think today I'm going for 38mm for the middle 4 and 23mm for the outer 4 that's the same ratio as the standard rover arrangement
Hi, yes that's mine:
Thread here although the photos are blocked by photobucket you can install a chrome app to make them viewable again.
viewtopic.php?f=18&t=12866
Or here:
http://forum.daxsportingclub.com/phpBB3 ... =35&t=4305
Dax Rush 4.6 supercharged V8 MSII

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Re: Equal length inlet tracts rv8 twin turbo

Post by SuperV8 » Wed Apr 11, 2018 1:16 pm

Before
Image2012-05-24180722 by t c, on Flickr

Image2012-04-20192920 by t c, on Flickr

After
Image2012-05-24194746 by t c, on Flickr

Image2012-05-24194801 by t c, on Flickr
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Re: Equal length inlet tracts rv8 twin turbo

Post by Twinturbotr7 » Wed Apr 11, 2018 8:10 pm

SuperV8 wrote:
Wed Apr 11, 2018 1:16 pm
Before
Image2012-05-24180722 by t c, on Flickr

Image2012-04-20192920 by t c, on Flickr

After
Image2012-05-24194746 by t c, on Flickr

Image2012-05-24194801 by t c, on Flickr
Hi tom , you have more trumpet To roof clearance with your gems plenum as standard than I had when my flapper plenum was standard , the gems plenum must be a bigger volume to start with , by the way I'm not using a flapper inlet manifold, just the plenum cover as I didn't want the capacitity written on it

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Re: Equal length inlet tracts rv8 twin turbo

Post by SuperV8 » Thu Apr 12, 2018 8:36 am

In the centre the GEMS and flapper plenums are the same height/clearence; I measured them.
The difference is the GEMS top is square, and the flapper top tapers down so roughly keeps the same clearance above each inlet tube.
But yes the total volume to the GEMS plenum would be slightly more than the flapper.

Tom.
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Re: Equal length inlet tracts rv8 twin turbo

Post by Twinturbotr7 » Thu Apr 12, 2018 4:37 pm

SuperV8 wrote:
Thu Apr 12, 2018 8:36 am
In the centre the GEMS and flapper plenums are the same height/clearence; I measured them.
The difference is the GEMS top is square, and the flapper top tapers down so roughly keeps the same clearance above each inlet tube.
But yes the total volume to the GEMS plenum would be slightly more than the flapper.

Tom.
I think if I was starting again with my plenum I prob would go with the gems one like you did , it would have been loads easier to Fabricate I had to weld a plenum base to my plenum cover so it was height enough to except the Thor throttle body , it was a right pain in the arse ,I think it's turned out nice in the end , I just didn't really want a land rover branded one under the hood of my tr7 (the bloke who does my ally welding thinks I'm barmy he dreds it when I come in , says I'm to fussy 😝)

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Re: Equal length inlet tracts rv8 twin turbo

Post by DaveEFI » Thu Apr 12, 2018 5:14 pm

Just grind any name or size off flush?
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Re: Equal length inlet tracts rv8 twin turbo

Post by Twinturbotr7 » Thu Apr 12, 2018 6:46 pm

DaveEFI wrote:
Thu Apr 12, 2018 5:14 pm
Just grind any name or size off flush?
If I was doing it again that's what I would do 👍

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Re: Equal length inlet tracts rv8 twin turbo

Post by volospian » Thu May 10, 2018 8:20 am

If you have accurate dimensions (or a CAD drawing, then I wouldn't have to draw it myself :)) I could CFD it for you. I'm looking at a plenum design for a V6, so it would be similar in concept in CFD.
No V8 at present :(

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Re: Equal length inlet tracts rv8 twin turbo

Post by Eliot » Tue May 15, 2018 8:14 am

Hi Chaps - can i copy these photos and put them on my Rover V8 manifold archive (the mez site listed on page 1)
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Re: Equal length inlet tracts rv8 twin turbo

Post by SuperV8 » Tue May 15, 2018 11:24 am

Fine with me mate.

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Re: Equal length inlet tracts rv8 twin turbo

Post by Eliot » Wed May 16, 2018 3:39 pm

to the o/p - i assume you are aware of the ACT plenum for the Dax/Westie:

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