Ported/polished Manifold and Head

[mcfly]

M-spec is the pot, and he just called mr kettle black.

[Opus]

No the rb25 head is a little big for the rb20 block. My reference to the rb25 was as an engine complete. Every time I talk about my rb20 build someone pulls " why bother playing with a 20 when the 25 exists". In my case it's just something to do. It doesn't cost me as much as someone who has to pay to do this. I don't want to suggest that you port anything yourself, if it's the first time you've ever ported a head. It takes alot of trial and error to get the skills to be proficient. You have to make a few mistakes along the way. Unfortunately this could cost alot as well. The rb20 head isn't a great head to begin with. The exhaust port had a big obstruction where the exhaust stud boss sticks out into the flow of air. I'm not going to make a huge flowing cylinderhead. I just want to improve what's there.

[sexonwheels]

Ya I definelty agree with staying with the RB20. It's something different and economical for everything I what to do.

[Skym]

From what I understand you don't need to port head for 300-400hp on RB20DET. On racespec RB20DET, they drop the compression into the 7's and up the boost for 400-500hp+. I gather they use boost to compensate for lack of compression.

This is the result -

http://www.youtube.com/watch?v=BIasNcIrZcM&feature=related

Would be interesting to see the flow figures when your finished. In Australia I think they mentioned that they hit the restriction in stock head at around 370rwkw or 560hp at engine with stock cams, etc. Although I think cams, traction, tall diffhead where the limiting factors.

The max hp in Japan with stroked bottomend (2.4litre) and modified head is 653ps.

[sexonwheels]

WoW skym, you amaze me every time you post. Lowering the compression and increasing the boost would be a wicked idea but the funds dont allow it at the moment....:hit_head:

So I can get up to 560 horsepower on a stock manifold and head?:-D...or just the stock head with an aftermarket manifold?

[M-SPEC]

M-spec is the pot, and he just called mr kettle black.

very insightful

Your right I was a little hypocritical on that one, but I thought I would introduce my self a bit more since others where doing so ..... and make it clear I’m not some noob talkin $hit

BTW you still have not quantified what you said about the valve guide hump

The good thing about forums is that people can discuss technical things like this and hey if de-burring and smoothing out the valve guide hump is

"the single worst thing you can do to a RB engine"

Then I would like to hear a logical explanation for this reasoning so other people will not make the same mistake if in fact it is … not a story about a kettle. This is still a million times better than another hesitation or freakin wheel size thread so lets keep the good technical info and threads coming

I agree with Skym 100%, on a RB20 there is little point on P&P it for the amount of power it will ultimately make. Don’t get me wrong I think they are great tough reliable motors that really can take a beating

BTW thanks Skym, the forums need more members like you, helpful, polite and backs what he says up

[Skym]

Thanks for the kind words. I think your kind, polite.

The engine was a play engine to see how much they could extract from stock RB20DET (stock cams, head, crank, conrods, pistons, block, etc).

Here's the thread on the roughly 373rwkw/560hp RB20DET at 35psi for 40-50 dyno runs -

http://www.nissansilvia.com/forums/index.php?showtopic=298289

This RB20DET engine was done on the cheap. I like the dodgy intake manifold, but it works.

There's another RB20DET on SAU forums producing similar hp but has cams.

Look at the RB20DET dyno thread on SAU if you want to see what some have extracted from RB20DET -

http://www.skylinesaustralia.com/forums/Rb20-Turbo-Upgrade-Dyno-t103095.html&

This is Roy's R32 RB20DET with around 400hp at engine with stock head, cams -

http://www.youtube.com/watch?v=dkP33kxpHvw

This boosted up 400hp at engine RB20DET is now in Canada with cams, similar turbo to Roy's RB20DET and was in the for sale thread on GTRCanada forums -

http://www.youtube.com/watch?v=_1JlZNPI6MQ&feature=related

Another 300rwkw RB20DET (stroked to 2.4 litre properly with HKS cylinder liner kit, etc) in Japan -

http://www.youtube.com/watch?v=wdDFBkdbljk&feature=related

Also you'll need to join forums to see the photo's of dynocharts.

[sexonwheels]

Ha I like the idea of the RB26 manifold fitting on the RB20. That would save so much money but might be a bit of work to get it to fit properly.....hmmm...maybe I'll try that in the spring.

What are some other decent manifolds other than Greddy that can get a RB20 to 500 horsepower?..Does Nismo make anything like this?

[Skym]

Nismo do make an upgraded intake plenum for RB26 -

http://www.300zx.com.au/pricelists/Nismo/nismogtrplenum.jpg

Here's a link to the thread on Nico forums with stock RB26 intake plenum, etc on a RB20DET -

http://forums.nicoclub.com/zerothread/307325

That's a similar look intake plenum to what they ran on the 653ps RB20DET engine in Japan. I was told the individual throttle body's are good for around 1000hp.

Also with the stock GTR intake plenum mod on RB20DET, you could fit the Nismo intake plenum.

Aim for around 400hp-440hp with RB20DET, which can be done with stock intake plenum.

Here's the RB20DET powered Skyline racecar with around 440hp (similar but different videoclip to what I posted above) -

http://www.youtube.com/watch?v=e-eafwz7eqA

This is what the RB20DET powered Skyline racecar engine bay looks like -

http://www.youtube.com/watch?v=8_iHWWiVBXs

[M-SPEC]

Good links Skym as always

There are a couple manifolds kicking around for the RB20/25

plazmaman (only a half mani and wayyy over priced)

http://plazmaman.com/shop/index.php?action=item&itemId=18

RIPS ...nice stuff not sure if they have RB20 but its a simple sheet metal manifold
http://www.ripsltd.com/products.html (bottom of the page)

And a couple on ebay , one has velocity stacks which greddy slacked out on

http://cgi.ebay.ca/NISSAN-SKYLINE-R32-RB20DET-INTAKE-MANIFOLD-RB20-plenum_W0QQitemZ330283219936QQcmdZViewItem?hash=item330283219936&_trksid=p3286.c0.m14&_trkparms=72%3A1215%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

Personally I’m just going to make my own, I like to make as much of my own parts as possible , heres a VERY rough Solidworks drawing of what I’m going to build , I’m still going to mess with the shape to find the optimum size and angle for maximum flow and efficiency because I can run simulated flow tests in the program before its even made

[Skym]

Thanks.

I like the intake plenum design.

Are you going to round the intake plenum more??? Or have you found a flow reason which says that a square edge flows better and is easier to make???

Why I ask is the Nismo intakeplenum is rounded around the plate that joins velocity stacks together.

This is my guess (if you don't mind me mentioning this) on one of many ways it could be made -

Velocity stacks made in a CNC machine.

With plate that joins velocity stacks together, could use 1/4 of a rounded pipe and cut it up. Then clamped on a drill press and drill holes for velocity stacks.

The top could be 1 piece. Use a piece of cardboard and cut the shape out . Then transfer to sheetmetal and cut out. Then bend into shape around a rounded pipe. Or use one of those sheet metal bending machines with multiple rollers (can't remember the name) to shape it.

Around number 6 velocity stack, cut a section of 90 degree mandrel bent round pipe, weld to main 1 piece of sheet metal to cap intake plenum. That way, when air reaches back of plenum, it's redirected smoothly into number 6 velocity stack.

For the front piece, where the throttlebody mounts to, use 1/4 of rounded pipe, clamp in a metal cutting saw. Then cut to desired angle and weld to the 1/4 piece of rounded pipe that joins the velocity stacks together.

The top part of front piece is another rounded piece of sheetmetal, which is drawn on cardboard and cut to shape. Then transfer to metal and cut final shape. Then bend in sheet metal bending machine and weld to intake plenum.

Then put front of finished intake plenum onto a piece of sheet metal. Then trace and cut the shape out. With the piece you just cut out, drill holes for mounting throttle body and hole in the middle for air to flow through. Then weld to front of intake plenum.

Or if you want the 1 piece to be 1 piece of sheet metal and a perfect shape, find somebody with sheet metal press that presses motorcycle fuel tanks, etc and design a mould for the press. Could use modelling clay or something like that for a template.

If you can flatten the shapes in the 3d modelling program and print out on paper. Then paste paper to cardboard and use as templates for the sheet metal. I guess it's a good way to see what it looks like before spending alot time and money in making a sheet metal version. Also gives you templates for mass production if someone else wants one.

[RyanGTS-T]

You need to meet my buddy. He's made several plenums from his 2jz 71' datsun 240z to various sr20 datsun 510's. He too has used velocity stacks, it looks unreal when you flip the throttle body open and see a line of them all perfectly aligned. To be exact I'm having him make my plenum for me. Already dropped the bottom half of the intake manifold off at his shop. Here's a phone pic of his work.

Good links Skym as always

There are a couple manifolds kicking around for the RB20/25

plazmaman (only a half mani and wayyy over priced)

http://plazmaman.com/shop/index.php?action=item&itemId=18

RIPS ...nice stuff not sure if they have RB20 but its a simple sheet metal manifold
http://www.ripsltd.com/products.html (bottom of the page)

And a couple on ebay , one has velocity stacks which greddy slacked out on

http://cgi.ebay.ca/NISSAN-SKYLINE-R32-RB20DET-INTAKE-MANIFOLD-RB20-plenum_W0QQitemZ330283219936QQcmdZViewItem?hash=item330283219936&_trksid=p3286.c0.m14&_trkparms=72%3A1215%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

Personally I’m just going to make my own, I like to make as much of my own parts as possible , heres a VERY rough Solidworks drawing of what I’m going to build , I’m still going to mess with the shape to find the optimum size and angle for maximum flow and efficiency because I can run simulated flow tests in the program before its even made

[sexonwheels]

Wow great stuff!:-)

The only thing about your custom plenum (M-SPEC) are the last 2 velocity stacks look like they wont get enough flow. The plenum goes big to really small toward the end where the last 2 stacks are. Can you test this part on your software?

I think I'm going to invest in an RB26 manifold and get my buddy to custom make me that mounting bracket. I think that looks wicked and I'll have the guarentee that it will be able to give enough air to the RB20 because it came off the RB26.

[Skym]

The RB26 intake plenum + throttlebody's on RB20 looks close to factory, except you can see the adaptor plate between throttlebody's, head.

[Opus]

Well I had purchased a stock head to get the baseline flow rates with, but some ***hole thought that you could port a head assembled. They gave up and ran the head afterwards. I didn't notice it untill I started to clean it up a bit. Some of the guides have been damaged and I have since disassembled the head. It's still good for my project but i won't be able to get the base line flow rates to compare with. Does anyone know somewhere on the net where I could get a flow map of the rb20 head at various valve lifts? (Not just peak flow #s, that worth nothing to me) I have searched and found nothing.