Jump to content
SAU Community

Recommended Posts

what if a good number high HP ones are still using the stock item?

I'm with you there!!!

Gary (Sydneykid) had a great post awhile back stating that changing to aftermarlet plenums have in most cases no gains and in some cases negative gains.

post-4055-1131577237.jpg

i see little point in changing either. there's nothing wrong with the factory one. i still wonder why nismo re-invented the wheel with their aftermarket jobbie.

d

The standard one may be okay for power, but with the standard plenum, more air is distributed to the rear cylinders which means an unbalanced engine and leaner mixtures on the rear cylinders (if you tune with one O2 sensor).

Hence why RB26's tend to always do ring lands on number 6, rather than one of the front cylinders.

And the flow differences in injectors can be substantial, even after something like an hour of cleaning there was a variation of over 5% in the injector flow rates, which could result in a difference like 12:1 target but one cylinder running at 13:1

It's not a terribly easy thing to flowbench test as it's impossible to accurately reproduce the conditions inside the plenum as they would be with the engine running. Pulsing and reversion will make a difference to the way the air is distributed.

You can test the percentage differences between the head with a bellmouth and the head with a plenum attached for each cylinder and gain some results from that.

The best way to test would be with an exhaust temp gauge on each manifold runner just out of the exhaust port. If you know that all the injectors flow the same and the rear cylinder runs hotter than the rest then you know that that cylinder is getting more air than the others.

Most decent computers let you trim each injector to compensate which can bandaid the problem.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Seat of the pants assessment of the new intake: The car is way less "doughy" when hitting the loud pedal, especially off idle when stopped or in traffic, I did use a cheapo lazer thermal thingo to measure the temp around where the pod filter got its air, it was between 55 - 60°C, in saying this the car was shut off and not moving, so the OEM intake pipe was not supplying any fresh air to where the pod was when the car was at least moving A weird bonus was induction noise on the throttle in the cabin increased a bit,  I was worried that I was actually going to lose some of that induction noise I love so much, outside though, when I got the daughter to do a WOT drive by pass for me, the induction noise has increased alot when on the throttle, not quite ITB doort, but well up there I'm extremely happy with the results and have been exploring the country roads in the region  As for house mods: 1.New front fence is up and is awesome, it really upgraded how the joint looks from the street, and the added security is nice 2. Electricians have replace some interior lights, and with more lighting in the garage, a few new motion detecting lights out the front above the garage, front room, and at the front door, which I have already found heaps helpful coming and going, also now has fancy pants CCTV all round the house The only hold point for power though is the solar and batteries due to supply issues, although this will happen over the next few weeks 3. I have done a heap of landscaping out the front and I'm almost ready to do a new small retaining wall with some nice blocks to replace the brick and cemented in rocks around the raised garden beds cemented in river stone "was the fashion at the time" the house was built. I currently have a pallet of retaining wall blocks and 2 bulka bags of 20mm blue metal to replace the wood chip that is in the raised garden beds around the house 4. I now have 3 big raised garden beds for out the back to grow some vegetables, about 70cm high, 200cm long and 100cm wide 5. My 2 compost bins are already pretty full with brown, green and kitchen waste from the landscaping I'vedone so far, but they will probably take a few months to break down, so anything else that gets chopped, trimmed, and kitchen waste will just start filling the base of the raised garden beds to about 30cm before I start throwing 40cm of good compost, and stuff, for the vegetables to grow in, I'll need a few ton of compost and soil, but the local supplier can sent me bulka bags of the stuff Basically the logs, wood chips and a few strategically placed rocks for drainage, will give the beds some good organic materials down low to break down over time, and they will hold moisture during the warmer months to save the water in my big arse water tank if we don't get alot of rain So, all in all, the car and house mods are going well, and I'm really enjoying being retired, I sleep in too 0700 and slowly plod around inside until I feel like actually doing anything, and only work in the yard for as long as want, which has actually been alot over the last few weeks,  although when you look at it, it seems that not a huge amount of work has been done,  until I look at the before I started the work pics Happy days and good times indeed 
    • hahaha yeah. Plan is to get side skirts and probably just rear pods. But going to do them one-by-one. I've got a set that I really like from RHDJapen, but that one isn't shipped to AU. So need to find someone who can get it for me
    • Here's an idea, answer the questions I asked you as they are trying to work out WHY the LSD will be binding up in a straight line.
    • You haven't driven many modern cars then have you? Most of them have sfa steering feel with their stupid electric bullshit steering systems.
×
×
  • Create New...