Cut And Shut Plenum

[Dose Pipe Sutututu]

Individual temperature probes on each exhaust runner (off the head).

Hotter is leaner. Simple as that.

yeah I know that too, but I was asking BLITZ-26 how his mate's tuner know that there were no lean cylinders.. most if not all tuners rarely whack on EGT probes on each cylinder exhaust runner

[AMR33]

I have seen two RB20s that died rather nastily with the same cut'n'shut plenum. After the second death, when the third engine went into the car, some thermocouples were installed into the exhaust manifold and some rather frightening differences in temperatures demonstrated. These differences were not linked to the injectors (as these were swapped around and also cleaned and flow tested as part of the ensuing paranoia). And when an unmolested RB20 plenum was put back on (with a Gibson style pipe to hook it up to the cooler piping on a temporary basis) the temperature differences all went away.

This was 16 years ago. The science hasn't changed since then. The only thing that has changed is whether the bodgy mod to the plenum gets the lucky angle or the unlucky angle. Whether the throttle body is set to swing one way or the other way, or any of a half dozen other reasons why one hacked plenum won't work at all while another will.

Can't help but think that had this been posted earlier; it would have been a real time saver. Well if this is true, then the resuts speak for themselves

[GTScotT]

yeah I know that too, but I was asking BLITZ-26 how his mate's tuner know that there were no lean cylinders.. most if not all tuners rarely whack on EGT probes on each cylinder exhaust runner

Oh right my bad lol I saw a question and auto replied lol didn't realise the question was aimed at someone specific about a specific comment made.

All good.

[Sinista32]

I'm too tired and lazy to read the whole thread tonight sorry. But has why been covered ?

Surely previous R+D has come up with the answer.

Can something be bought off the shelf that works ?

If price is an issue then I'm certain there'd be "copies".

Is there significant benefit over stock for your application/needs ?

[AMR33]

I'm too tired and lazy to read the whole thread tonight sorry. But has why been covered ?

Surely previous R+D has come up with the answer.

Can something be bought off the shelf that works ?

If price is an issue then I'm certain there'd be "copies".

Is there significant benefit over stock for your application/needs ?

Better to read the thread but as to your 3 questions:

To reduce length of intercooler piping (supposedly more response)

Perhaps an aftermarket forward facing plenum

No significant benefit

[FineLine]

Live with one and live without one, I wouldnt go back to stock piping.

[Sinista32]

Thanks mate

Now that I've read the thread I think I'll sit on the side line and maybe learn something.

Side note: Went down a path for an aftermarket plenum for my 32.

Purpose was to reduce temps, improve airflow to rear cylinder/s, and a minimal response/power benefit.

I'd worked pretty much everything else on the car and this was the last thing I did performance wise.

Hey Noel, your on the track regularly aren't you? Did you go aftermarket or do a cut/shut on existing ?

We both have different Skylines to Abdul so I have no real clue about a 31 Cefi. So suppose I shouldn't be commenting.

Personally I wouldn't attempt a cut n shut myself.

Edited August 23, 2013 by Sinista32

[ARTZ]

I have seen two RB20s that died rather nastily with the same cut'n'shut plenum. After the second death, when the third engine went into the car, some thermocouples were installed into the exhaust manifold and some rather frightening differences in temperatures demonstrated. These differences were not linked to the injectors (as these were swapped around and also cleaned and flow tested as part of the ensuing paranoia). And when an unmolested RB20 plenum was put back on (with a Gibson style pipe to hook it up to the cooler piping on a temporary basis) the temperature differences all went away.

This was 16 years ago. The science hasn't changed since then. The only thing that has changed is whether the bodgy mod to the plenum gets the lucky angle or the unlucky angle. Whether the throttle body is set to swing one way or the other way, or any of a half dozen other reasons why one hacked plenum won't work at all while another will.

is it me or is it pretty bloody obvious you just made that up to try save some face.....

let me make a story up....back when nIrvana were still top of the pops we cut n shut the plenum on an almost new rb25...at the time it was a never thought of idea and there was no internet available to get online an bounce our ideas with other self proclaimed geniuses, so we thought we should stick a temperature prope in every exhaust port... So we did it, an EGT stuck in every runner...it s a somewhat expensive excercise but back then an rb25 was worth like a squillion dollars so we thought it was worth it... the results we found were fine, we had perfectly even heat distribution across all cylinders.. wh then thought we should double check so we put a wideband in every runner, which is pretty silly because widebands dont like heat and should be placed further down the exhaust anyway but we thought it was definately worth sacrificing some very expensive widebands because it was definately worth it, it was an RB afterall.....It made about 400kws...which was alot back then....unfortunately we did not document everything on a website for your perusal and even if we did it would be well lost in the archives by now. but that engine is still running strong..You will have to take my word on that though ...

That's the problem with ignorance. Some people just keep re-stating the same point of view until people with actual knowledge get frustrated at the lack of rational discussion, throw their hands in the air and give up.

thats the problem with know-it-alls they keep reinstating the same point of view when they have still brought no factual evidence of anything...

I've given up because you have brought nothing but theories to the table and a lot of slander...

I dont know what makes you believe your argument is any more valid than mine...Just because you have your hand in GTSboys pocket doesn't automatically make it right, its just means you get might get a reach a around in the showers at night...

so to come down to you're level...You're an idiot!....and inline with this conversation I am also changing my signature to reflect upon yours, I even made it a funny colour so it really stands out ...but unlike you, I actually thought it up myself..

Can't help but think that had this been posted earlier; it would have been a real time saver. Well if this is true, then the resuts speak for themselves

Thats because its a load of crap...

[ARTZ]

So GTSboy seeing as you're the physicist. ..a small test...if we were to get an RB complete intake side...attach a plate or some tubes with basic a pressure sensor, like a tyre gauge to the end of each runner and fill it with compressed air via the TB and then take the readings from each gauge... would this be a effective enough representation of real world events?

[Ben C34]

So GTSboy seeing as you're the physicist. ..a small test...if we were to get an RB complete intake side...attach a plate or some tubes with basic a pressure sensor, like a tyre gauge to the end of each runner and fill it with compressed air via the TB and then take the readings from each gauge... would this be a effective representation of real world events?

no. Not at all.

[ARTZ]

no. Not at all.

because ?

[Ben C34]

If you put a pressure gauge in the fuel reg port it would show the same psi reading as the rest of the gauges on the inlet ports based on sealing off the ports.

Edited August 24, 2013 by superben

[GTSBoy]

Oh f**k ARTZ. You have no idea that there is a massive difference between static pressure and flow do you?

By the way. The RB20 I spoke of was in an S13 that was associated with the JMS crowd in Adelaide. I don't think it was Danny's as he only ever blew his engines up from simply leaning on them too hard. But this S13 was running a TD06 highmount at about 26rwkW like Danny's. My brother-in-law was the one working on the car to try to work out why it was going pop. Would you like me to give you his business phone number?

Edited August 24, 2013 by GTSBoy

[ARTZ]

Oh f**k ARTZ. You have no idea that there is a massive difference between static pressure and flow do you?

i'm over trolling this thread...have fun guys....

[Tonks]

^^ this.

Off topic, that Gibson31 AFM gets me everytime haha funny kents

Edited August 25, 2013 by Tonks

[Ben C34]

Back on topic. How much time would you actually save when changing plugs anyway without the crossover pipe? 5 minutes? Then factor in how long the install of a ffp takes. ......

[GTSBoy]

That's long been one of my arguments. I take the crossover pipe off the car more often to carby-clean the TB than to touch the igniton anyway.

[ARTZ]

nice plenum on this big turboed 25/30....wonder how long till the engine explodes

[PSI086]

Who cares how long it lasts lol. That thing is awesome

[Soundboyracer]

Look at the differences between and look at the last cylinder in the aftermarket intake. Noting much right?

You think that engine will go boom?