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what sort of comp ratio is gona be best? as above, using standard, prepped internals, need to no what size gasket to use. lookin to run about 1.5bar, 550cc injectors, microtech ecu and do away with afms, may be a set of pom cams and adjustable pullies?

antone no what software the microtech uses, and wat contest there is between the power fc?

I used a Sub Zero style cylindrical plenum on top of the standard lower inlet manifold of the RB25DE top end that we used.

I have been looking for pics and info on the sub zero plenom and other plenoms that bolt to the lower inlet RB25det manifold.

Anyone have pics and/or know where I can get one of these?

Ben.. just curious  (i just addded u to msn btw - so i'll be having a chat to you when i get home :cheers:)

do you have any pics of the engine in the silvia? or is it yet to enter the engine bay

i'm just curious because my car has just been through rb25det conversion - and i want to see the height of the RB30 in the S13 engine bay

cheers

BRAD

Engine is not in yet. Not far away now.

I know it won't fit.. so I am going to lower it as much as possible, remount the sway bar (or make a custom sump to clear) and possibly make a custom bonnet.

:P

I have been looking for pics and info on the sub zero plenom and other plenoms that bolt to the lower inlet RB25det manifold.

Anyone have pics and/or know where I can get one of these?

RIPS do an excellent one - see pic below. Keeps all factory sensors, unlike the Sub Zero and Greddy ones...It uses true short runners, unlike the cut and shut job Sub zero style....

His email is [email protected] - Damn good quality if you ask me...he does kits for any type head you have for $1500 NZD ($1350 AUD) comes painted in your choice of colour too :P

RIPS do an excellent one - see pic below. Keeps all factory sensors, unlike the Sub Zero and Greddy ones...It uses true short runners, unlike the cut and shut job Sub zero style....

Greddy plenum keeps all the factory sensors, idle control equipment and has short runners too. Not that short runners are by any means a good thing, especially on something as low revving as a RB30DET.

Sub-zero plenums look ok, have long runners (a *good* thing) but use none of the factory equipment, and I do hear the odd negative story about them here and there. Main problem causer is they don't bolt on to the lower half but weld on.

RIPS might be ok, just don't know enough about their plenum to have anything against them.

As far as i know (which aint that far :P) the Greddy one doesnt have one of the cold start sensors that the Power FC uses (one of the factory sensors?)

Since when were long runners a good thing? I read on this forum (from a reliable source) that the Jap tuners said its the runners that were the main reason for the change to the front facing plenums...hence the design of the greddy one, which also tapers to the rear. Rips uses the same design as the greddy one shorter runners, and tapers to the rear, unlike the sub zero style one which uses factory runners, with a square top welded on it.

Looks like the design was more influenced by the need to move the throttle body if you ask me...But this thread should stay on track, its too long to argue over which FFP is a better design ;)

I found a great way to get my intercooler pipe (which runs along the front of the engine) to fit under the bonnet. After having a good look at it i noticed the main problem was the fan was geting in the way. So i'm going to pack out the fan by about 20mm, where the fan bolts onto the water pump. This will allow me to lower the intercooler pipe enough to clear the bonnet. Also with the fan being closer to the radiator it will make it more efficient.

Since when were long runners a good thing? I read on this forum (from a reliable source) that the Jap tuners said its the runners that were the main reason for the change to the front facing plenums...hence the design of the greddy one, which also tapers to the rear.  

Theres more detailed info on this, but basically runner lengths are tuned for a rpm range. Short runners are better for high rpm and long runners for low rpm. In fact, the best setup for low down torque for most engines would result in runners over 500mm. Not practical under a bonnet, and the reason why manufacturers like to curl runners to extend their length.

Short runner setups may be good for high reving rb25s and 26s but they'd be less than optimal for a rb30 that has a 7000rpm redline. Its not stopping me from using a Greddy plenum on mine, but thats still the facts :P.

But this thread should stay on track, its too long to argue over which FFP is a better design ;)

Agreed. ;)

I was always lead to believe short runner lenghts are for low RPM (diesels have great torque down low and have very short runner lengths) and long for High RPM. That's why some cars have the curled runners and in that a butterfly opens and closes. Making the change to a short runner by opening and bypassing the big curl and going to a long runner length when it closes, N/A falcons have the same setup to give the best torque all around. Turbo XR6's dont have the butterfly so the air bypasses the long curve of the runner so you have the torque down low and the turbo gives the great airflow up high. I have also seen N/A cars that have trumpets that increase in length as the engine's revs increase.

Have I been led down the garden path all my life??????

I was always lead to believe short runner lenghts are for low RPM (diesels have great torque down low and have very short runner lengths) and long for High RPM.  

Have I been led down the garden path all my life??????

I think you may have just been a little mixed up :)

Have a read of this: http://www.autospeed.com.au/cms/A_0122/article.html

In particular paragraph 7:

In a Helmholtz Resonance system (one with runners connected to a common plenum), US-based engineering guru David Vizard suggests that a runner length of 17.8cm at 10,000 rpm makes a good starting point. (In this context, "runner length" refers to the distance from the inlet valve to the plenum chamber.) Add to this length 4.3cm for each 1000 rpm less that the system is being tuned for. Tuning for peak torque (not peak power) is the norm, and so if the engine were being tuned for 4000 rpm, a runner length of 43.6cm would be required.

I know it's getting of the RB30 conversion topic but how come diesels produce good torque down low with short runners?

Open the bonnet of any Toyota landcruiser and you'll see very short runners joining onto a common plenum.

Not trying to get into an arguement, just want to now why what i see being used goes against the pricipal's explained in that article?

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