Anyone know the characteristics of the JD plenum? Tossing up either the JD or Rajab. like the look of the JD more, but read good things about the Rajab

Quote: Originally Posted by AVG45 [View Post] Yeah bit his mate said JPC was the best? Basically it depends on what you're after with your car... If you like the RAJAB plenum, you're keen on a bit more low down and maybe (only slightly) less up top with the standard runner length, then by all means go for the RAJAB. If you like the JPC and are willing to sacrifice a little bit low down for more top end with the shorter runners, go for the JPC, or have a chat to Ariel (ISL33P) Custom Plenum Creations who seems to have a lot of knowledge on inlet manifolds, and also who has back to back testing showing the improvements by fitting one of his manifolds.. how will a pressurized plenum make more or less torque with a difference in runner length?

Quote: Originally Posted by bachig24u [View Post] how will a pressurized plenum make more or less torque with a difference in runner length? Usually the runner length & cfm play a good roll in torque difference's. There's also a difference between the NA & turbo plenum. I believe the NA plenum flows better. But I thought shorter runners give you more torque & top end.

you cant beat the modified standard inlet, seriously bang for buck etc, also theres something about a low mount and the vlt still present that to me says, Dear nissan/holden we appreciate the millions you prob spent on r&d but myself and afew mates made afew adjustments and heres a 9sec 1/4 time slip Ive got a standard modified (sydney spec :P) one on mine and it just works so bloody well, the 700roller comes on boost like a t3 and it makes ample power In terms of aesthetics, i personally couldnt go past a jpc one but thats just me

Quote: Originally Posted by Morgz [View Post] what do you mean by best results? If you're talking flow rates it's not the JPC plenum, and if you're talking MPH it's also not the JPC plenum. Outright top end dyno results mate thats all, for street use I'm with Katsta you can't beat the standard manifold modified.

Quote: Originally Posted by PROMASTER [View Post] Outright top end dyno results mate thats all, for street use I'm with Katsta you can't beat the standard manifold modified. Well if that's the case, going by mph, you'd probably be looking at one and the same manifold Some original photos have not been recovered yet.

Quote: Originally Posted by bachig24u [View Post] how will a pressurized plenum make more or less torque with a difference in runner length? oh my favourite internet comment....the good ol' pressurised plenum comment. Can I interpret that comment as saying that changing runner length will not change torque and ie horsepower - yes pressure is equal within all runners - NO that doesnt mean it flows the same or makes more/less power/torque - torque is directly related to runner length and cam duration at a certain rpm.....one can not go without the other - pressure has NOTHING at all to do with flow, well CFM. Pressure is a measure of air density - and to throw a spanner in the works, airflow does not change with the introduction of a turbo/supercharger I am happy to point people where to look if they want more info on this, just to clarify it and so you can see it for your own eyes and not just on an internet forum

Post away, sounds like some interesting reading Some original photos have not been recovered yet.

Quote: Originally Posted by ISL33P [View Post] oh my favourite internet comment....the good ol' pressurised plenum comment. Can I interpret that comment as saying that changing runner length will not change torque and ie horsepower - yes pressure is equal within all runners - NO that doesnt mean it flows the same or makes more/less power/torque - torque is directly related to runner length and cam duration at a certain rpm.....one can not go without the other - pressure has NOTHING at all to do with flow, well CFM. Pressure is a measure of air density - and to throw a spanner in the works, airflow does not change with the introduction of a turbo/supercharger I am happy to point people where to look if they want more info on this, just to clarify it and so you can see it for your own eyes and not just on an internet forum ^^^ This man knows his ****

calais25t - I can't go past a good (edit) book for the simple convenience of having it at your fingertips. Basic forced induction books can give you detail and then ones like "Engine Airflow" and "Scientific design of exhaust and intake systems" are both very good reads haha pro747 - maybe its just that I dont believe all the **** people post on forums.....thats what has lead me to do my own research and reading quality publications/non-model specific forums

Quote: Originally Posted by pro747 [View Post] ^^^ This man knows his **** Mate you need to wake up to your self, how can you say the speed of airflow will not change with the fitment of a turbo or supercharger. Do your homework bud.

O oh, here we go. Prove me wrong

Quote: Originally Posted by Morgz [View Post] Well if that's the case, going by mph, you'd probably be looking at one and the same manifold I remember Jules posting on here that apparently mautooks dynoed the hypertune plenum on his orange vl and it was the only plenum to make more power than the mautooks modified stocky, could be wrong, but thats what i remember getting posted on here. cheers darren Some original photos have not been recovered yet.

hahaha I am happy to admit that there isn't a well designed plenum on the market that wont increase HP...rajab, jpc, nizpro/bresciani, JD, hypertune. As how they compare to the modified stocky, well some people have their own agendas to push and points to prove, which is more likely the reason why those results come to light. I will bet my left...no actually, both testicles that mine and almost any of the plenums I mentioned above will make more hp than a modified stock one any day of the week....... edit - one thing I should add and as an edit to my previous post; - airspeed does not change from NA to FI. the peak airspeed is just reached quicker with FI compared to NA - air density (ie FI) is the reason for increased hp - i have also read that airflow does not increase when FI, again it's the air density (this is can be quoted from Allen Lockheed, reknowned US aircraft manufacturer) all remembering that boost is the measure of a restriction

Quote: Originally Posted by PROMASTER [View Post] Mate you need to wake up to your self, how can you say the speed of airflow will not change with the fitment of a turbo or supercharger. Do your homework bud. As mentioned in this post Quote: Originally Posted by ISL33P [View Post] edit - one thing I should add and as an edit to my previous post; - airspeed does not change from NA to FI. the peak airspeed is just reached quicker with FI compared to NA - air density (ie FI) is the reason for increased hp - i have also read that airflow does not increase when FI, again it's the air density (this is can be quoted from Allen Lockheed, reknowned US aircraft manufacturer) all remembering that boost is the measure of a restriction All a turbocharger/supercharger is doing is compressing more air into the engine (ie Compressor housing), the air is more dense, more air molecules per intake stroke, therefore more fuel can be added, therefore more power, it's not the speed of the air because it can only go as far as the piston on the intake stroke, the turbo/supercharger is just trying to cram as much air into that stroke as possible, a engine is just a pump the more you can put in the more you get out.

Ding ding ding we have a winner!!!!

[QUOTE=MxPx VL;2968009]As mentioned in this post All a turbocharger/supercharger is doing is compressing more air into the engine (ie Compressor housing), the air is more dense, more air molecules per intake stroke, therefore more fuel can be added, therefore more power, it's not the speed of the air because it can only go as far as the piston on the intake stroke, the turbo/supercharger is just trying to cram as much air into that stroke as possible, a engine is just a pump the more you can put in the more you get out. My Dear boy i wasn't refering to his entire post on the part thats stated airflow does not change with the introduction of a turbo/supercharger which isn't correct.

man this is like being in a science class at school but actually enjoying n learning from it haha!!!!

Airflow, as I was referring to as CFM, doesn't change so what's your point? Some more theory : - Theorectically, increasing the air pressure, remembering atmospheric pressure is 14.7 psi, to 29.4 psi (14.7 psi of boost pressure) should double that same engines horsepower, triple for 34.1 atmospheric pressure (29.4 psi boost pressure) and so on and so on

Quote: Originally Posted by ISL33P [View Post] oh my favourite internet comment....the good ol' pressurised plenum comment. Can I interpret that comment as saying that changing runner length will not change torque and ie horsepower - yes pressure is equal within all runners - NO that doesnt mean it flows the same or makes more/less power/torque - torque is directly related to runner length and cam duration at a certain rpm.....one can not go without the other - pressure has NOTHING at all to do with flow, well CFM. Pressure is a measure of air density - and to throw a spanner in the works, airflow does not change with the introduction of a turbo/supercharger I am happy to point people where to look if they want more info on this, just to clarify it and so you can see it for your own eyes and not just on an internet forum I hear you, and no I wouldn't interpret that question as a comment, just read it as it is. the question was aimed to clarify what one would know about what they were offering as advice to begin with. I've also re-engineered the RB30 & 25 inlet manifold in an effort to improve upon the other buckets of alloy waste material that I've come across. Measurable improvements in cylinder filling, throttle response, BSFC and driveabilty at atmosphere and above are noted. I see the log manifolds that guys come up with and think to myself, well at the very least, air should get in to the engine somewhere if theres no leaks! but each to their own.