Exhaust Manifold top mount rb25 suggestion

[DynamiteQC]

Iam gathering part for the build and Iam clueless about what too look for when buying a top mount manifold. What are the downside of buying a lower cost manifold ? What are you running or suggesting. I am planning on pushing in the 500whp range.

[PurpleStreak]

Upside of buying cheap manifold is cost. downside is poor fitment, making expensive rework likely,and likelihood of welds cracking high.

A T4 flange manifold would be a good size. You can look into either twin scroll or quick spool valve to help with spool.

Wastegate sizes vary with 38 to 60mm sizes for regular manifolds. I would personally prefer 321ss for material however lost manifolds are made of regular carbon steel or 304ss.

I have a lovefab manifold that should fit Rb25 for sale. check my FS thread if interested.

Sent from my MB860 using Tapatalk 2

[DynamiteQC]

Mind you , I will be getting a precision 5830. I was told stock manifold can do the job if ported , but a topmount give you easy acces to the turbo incase something break. I will check your add but buying the part won't go until end of winter.

[Skym]

Only top mount exhaust manifolds that are known to be good are :-

6boost -

http://www.6boost.com/

Sinco customs -

http://www.sincocustoms.co.nz/products/Nissan%20RB20-25-30%20Top%20Mount/16

I think both brands are made of thick steam pipe for runners and have thick flanges so they don't warp. Only problem is they are heavier than cheaper aftermarket exhaust manifolds.

[DynamiteQC]

6boost website is underwork and the sinco one have no price tag. I don't think the weight on the manifold will bother me alot.

[Skym]

If search web, sometimes cost is mentioned.

Also probably would need a adjustable tension bar or similar from engine mount (metal part that bolts to engine) to turbo flange and a flexi in front pipe, just like what is used on Honda exhaust's to not snap exhaust studs or rip them from head.

[DynamiteQC]

cool thanks , I will take the time to find the price tag. While Iam at it , does anyone have a build thread of a rb25det pushing over 500 whp? I will be looking for one in the project page and google also.

[Skym]

RB25DET engines with that sort of hp have RB26 crank, RB26 H beam conrods, RB26 forged pistons inside stock RB25DET block, 1.2mm metal headgasket. Cams used are the same as RB26, so Tomei 260 duration cams with adjustable exhaust camgear, Tomei valve springs, Tomei solid lifters should be good enough for 700hp at engine.

Basically what mods work on RB26DETT, works on RB25DET as far as fuel, bottomend, intake manifold (Can fit stock RB26 intake plenum with adaptor plate), cams go. Basically you are making a RB26DET out of a RB25DET (better to start with RB26, as less work involved and have solid lifters, etc). Turbo, FMIC are sized to suit powerlevel.

Or you can fit a RB30 bottomend (more hp, torque than RB25, RB26) -

http://www.ripsltd.com/products.html

Size of intercooler core vs hp you want (turbo + engine combined) is here -

http://www.turbobygarrett.com/turbobygarrett/intercoolers

Then search for turbo (right side) that matches the hp you want and research at what rpm full boost is on that engine -

http://www.turbobygarrett.com/turbobygarrett/turbochargers

Injector sizing calculator is here (stick to 80% duty cycle max) -

http://www.deatschwerks.com/fuel-calculators/

[DynamiteQC]

thanks alot for all the link. I will be looking into them when I get back home.

[nick-nismo]

I bought one of thoes 170 dollar eBay manifolds. I had to cut and re angle the flange for turbo clearance and I also added a bigger port in the collector for wastegate and better boost controll.
There's definatly something to be said for buying brand name products.

[markdett]

Try ETM manifolds too, merge collector design's a bit better then the 6boost (dont get me wrong 6boost are awesome). Powertune here in aus also make a nice manifold and can custome make with the appropiate flanges/wastegate ports.

One tip ill give you is to use the OEM nuts and yokes when fitting these manifolds as the nuts supplied will tend to seize unless copper coated.

A friend of mine is running just under 500hp (480 @19psi) with a stock internalled RB25. His running a garrett GTX3582R, 640cc nismos, bigger fuel pump, plazmaman plenum, PowerFC with z32 AFM, bigger cooler ETC. Does 3rd gear stand still's but is now having diff troubles as he keeps snapping shafts/gears. As I said the engine is bone stock and has only had 1 engine fail due to hitting limiter and breaking valve spring retainer which intern dropped a valve. $1500aud later and his got another stock engine in there and its still going strong.

Heres a clip for your veiwing pleasure.

http://www.youtube.com/watch?v=7iWSWDEFiig&list=UU0DgpMo259EHp0E5JCQj82Q&index=1&feature=plcp