Dual plenum inlet on 4G63

Hello

I am about to start building up my new engine & along with the refresh I want to make changes/try things out.

Ill provide a bit of info on my setup, use etc

2004 JDM Evo 8, imported to the UK approximately 2.5 years ago and the car was totally stock.

I’m not really interested in track work, this is purely a fast road car. I have always done all of my own work and over my 26 year obsession (pain sometimes😆) I have gained several skills, Tig welding, light fab work, engine assembly, stand alone tuning is my top number one interest! By no means am I a professional, however I have had quite a few very good results, I think nowadays ECU tuning is so easy to get into and in the nicest possible way - just about all ‘car guys’ are tuners to some degree, I feel I’m reasonably competent & confident at it, I don’t tune for customers etc…I have been a mechanic since leaving school so as you can imagine, my trade has brought about allsorts of skills.

I don’t want to go off course here, I feel it’s important to give the full picture when asking questions like this….Anyway, back to the car…

My previous fully built engine suffered from a major sudden issue which lead to Number 4 piston damage, tbh it’s still a mystery as to exactly what happened, I use just about every safety feature that MaxxEcu offers and the weird thing is nothing was triggered, no lean condition etc etc. I always felt this engine was very ‘noisy’ piston slap was very noticeable and always bugged me, it’s worth noting that This is the only engine that I bought as a fully ready to go assembly, it had all the right parts, price was very fair etc.

This time round I’m keeping it fairly simple, I am using what I can from the previous engine that is fit for use..

stock bore & stroke 4G63

Manley rods onto stock pistons, ACL bearings, ARP Main & head studs,

Cylinder head is mostly what i consider to be stock, Kelford 272 cams, Vernier pulleys, supertech valves/retainers, fresh set of guides, Uprated springs. Ports have all the rough casting marks smoothed out, NOT full on port job!

Internally that’s about it.

I will be using my new Artec Low mount manifold along with a Garrett G25/550 .72 possibly bigger as I have 2 different housings here to use, 45mm EWG

3.5’’ downpipe 3’’ system

walker 255 pump, Radium ‘higher flow’ Jet valve (saddle tank thing!)

stock lines

Radium rail with Bosch 980cc injectors, Adj FPR

Bosch 76mm E throttle

MaxxEcu Race Ecu on custom harness

This is where things will change a bit…

Ive always been intrigued about the Dual plenum thing and there are DIY kits available to buy from a a company in Norway, it looks to be a fairly extensive kit, and from my research quite a few people have done it and have gained good results.

I probably don’t exactly need a dual plenum, it’s more of an itch that I want to scratch!

I’m aware that Evo stock inlet manifolds don’t provide even air distribution specially to Cyl 4. Again from my research, the dual plenum aims to give MUCH better distribution to all 4 cylinders, the one thing that slightly concerns me is that they are designed / or can at least be specc’d to focus on a particular RPM & power & torque range…

With the Turbo I’m using, due to its small size I won’t be aiming for huge figures or expecting to rev crazy high, looking at my complete setup I would expect to make a good 400hp/400ft lb with ease and I’d expect it to have its sweet spot around 5k Rpm,

As it’s a purely a Fast Road car I think it’s important to understand reality & respect the fact that most of my road duties will be mid rpm. If dual plenum intakes are to give good results around a specific RPM range then it’s only natural to assume that I should build the manifold to suit MY expected rpm and power goals. I am expecting people to say stay with the stock inlet but as previously mentioned it’s something that’s interested me, costs are well within reason and from what I gather, a dual plenum can’t exactly have a negative impact on my setup/use case.

I think I’m looking for other peoples experiences, opinions, tuning tips etc. For a 400/400 road car engine what would i ideally do about the throttle body size? I am currently running a 76mm Bosch E-Throttle and I would assume this wouldn’t be a bad choice for the new Dual setup??

In reality, what improvements could i expect to see?

What negative results could there possibly be?

Is it reasonable to assume that lower boost pressure would be required to achieve a certain figure compared to a stock plenum?

I’m keen to hear anything tbh, I really want to try this and compare Data to stock intake.