Precision motorsports Rb25 H-Beam rods

[MATTs14]

Anybody got anything to say about these? Good or bad? Just need some opinion on them.

Reason im asking is im getting an rb25 from RawBrokerage, who i must brag on for their excellent customer service, and i want to beef it up little all the way around. I either wanna do rods or at the very least arp rod bolts. Let me know guys and thanks in advance. Thanks

[Darius]

Rods are not the weak link. Replace pistons and rod bolts if you want a stronger bottom end.

[MATTs14]

What pistons do you suggest?? Ive looked at wiseco and cp but not sure whats preferred.

[Darius]

Both are fine. Look for the best price if those are your two options.

[MATTs14]

Ok well ive settled on the 86mm CP pistons. Since this is the standard bore will i need any machine work to make these work?? Sorry for the newb questions guys just kinda nervous about building the bottom end since i wanna do it right the first time. Thanks

[Darius]

What are your power goals for this motor within a 2 year time frame? This will determine whether you even need the pistons right now. Pistons basically equal a full rebuild.

[eh?]

Ok well ive settled on the 86mm CP pistons. Since this is the standard bore will i need any machine work to make these work?? Sorry for the newb questions guys just kinda nervous about building the bottom end since i wanna do it right the first time. Thanks

Yes machine work will be needed. There is no real standard bore or pistons, as they each have about 3 or 4 "standard" sizes. Your gonna machine your bores to match your pistons+clearance.

Also I'd really recommend researching the specs used to make the pistons. A few years back when I bought my pistons, Ross racing was the only one to have the right specs. The rest were wayyyyy off.

[MATTs14]

500whp max or whatever my holset hx35 runs out at. I would really like to settle on 400-450whp and be reliable. I realize its gonna need some machine work but i also realize that i dont need to go to extremes when doing so. I really just wanna replace the pistons with something that isnt gonna crap out on me the second i start making some respectable power. I realize that its also expensive. I wanna do some form of piston whether it be cp, ross, wiseco, or any others, get the block and head resurfaced, replace the bearings, main studs, head studs, rod bolts, headgasket, and get a better crank collar, and freshen up all the rest of it. I've had an rb20 for going on 2 years now and im ready to move on.

I guess what you guys are saying is dont try to match pistons to the motor, match the motor to the pistons, within reason of course, and thats completely understandable.

[eh?]

400whp is fine on a 100% totally stock RB25 long block. I've been doing it for years now. It really depends what your gonna want to do with the car. If your going to do drifitng or some sort of autoX, I'd do the full build. But if it's just daily/ weekend 1/4mile car you 'll be fine stock.

I paid about $1k in machine work+balancing when I built a motor, I assembled the bottom end myself, they assembled the head.

[MATTs14]

well thats really reassuring, thank you so much. I really want to get in the upper 400's or maybe even dip into 5, which i thought would be fine, but i had heard numerous times that the pistons were weak and that the ring lands were the first to go.

Its gonna be my daily driver with the occasional trip to the 1/4 mile, nothing really crazy, but the power will be there if i decide to turn in it into a devoted track car.

[eh?]

Good tuning goes a long way. The ring lands are supposedly weak but most of the evidence comes from Australia and their Dyno Dynamic Dynos read way less than our usually DynoJet and Mustang Dynos. Can't really correlate their numbers to ours so we can't really say what the limit is. Plus the fact most of them are using PFC's with no knock/egt control...

[MATTs14]

What do you suggest as far as tuning goes??

Ive had my eye on Carl H's tuning and from the looks of it, he does a great job. My buddy just got an ecu back from him and he did an amazing job. I know he can do a chip tune but do I need something to fine tune it with and sort of fill in the cracks to get it spot on??

Im not a big fan of apexi's afc's so thats pretty much out of the question. I want something thats reliable, but wont break the bank.

[Coolwhip]

Hey Matt,

I'm at the same power levels as you are seeking on a stock motor with a GTK500, but fully aware what potential dangers await me if I'm not carefull.

Would a build do you well? Yes. Is it called for right now? No.

Some great suggestion above as well. If going into the block you may as well do the full setup and do a slight bore for the piston job.

You can get the rom tune pretty fine tuned, Carl does a great job on that speak to him.

[Darius]

To add to eh?'s comment about the Aussie RB25 piston failures, a lot of them were caused by guys installing miscellaneous aftermarket ECU's that they didn't know the details of the tune and also by guys cranking the boost up without tuning at all. I swear half of them were TRYING to knock their motor apart because nobody with half a brain would turn up the boost to the levels that they did without tuning the motor first.

Tuning goes a long way for reliability. If you can get 450hp and tune the timing so it doesn't knock, you should be good to go. That's why I say just drive it until it breaks and THEN rebuild it.

[Coolwhip]

That's why I say just drive it until it breaks and THEN rebuild it.

[MATTs14]

Thanks for the friendly advice Ricky. You always have some good words of wisdom. I believe that i will shoot for mid 4's on the stock block and build up some funds and build it in the near future. I would love to dig into the head and everything while im in there when i do the build to make the same power without having to stress everything so much.

From gathering info from all of you guys responses, i pretty much get the feeling that the stock block is the way to go for now, and if i decide to beat on it a lot, then definitely go for the build. Sound about right??

Also are all you guys running the oem headgasket??

Thanks again everybody

[Coolwhip]

Nissan can identify all their parts from valve cover to oil pan on my engine. :P

[MATTs14]

Thats exactly what i was thinking but didnt wanna say it. Ive always felt that rebuilding something before you even know it runs is kinda risky. Im glad im not the only one who thinks you should test the true potential of it before you go making it bulletproof.

Thanks guys

[Coolwhip]

True, but throwing a rod through the side of a block isn't best practice :P

We'll talk

[MATTs14]

Ok shoot me an email, if you dont mind, with some pointers. Thanks again guys

[Cjmartz2k]

Stock RB25 bottom end is good for 500+ USA rwhp I had a HX35/40 hybrid on there for over 1 1/2 years, and have been rocking a full HX40 at 1.8 bar for about a year on top of that. My buddy has a HX52 on his and he's at 95% on 740cc injectors at only 1.6 bar on a stock bottom end. The aussie guys listen to their own internet BS to much. It's all in the tune.

[blurrbosi]

1. aem. or pfc 2. exh manifold with your turbo3. decent intake manifold 4. 2 walbros, fpr, 1000cc?s 5. dyno time...stock bottom end. 450-500 all night

[MATTs14]

Thats awesome guys. Im definitely gonna go ahead and shoot for 500whp then. I definitely know that i wont be doing that with the hx35, possibly a 35/40 or a full 40, so if you guys see one for < $400 or so then give me a shout.

Also CJ i believe ive asked you before but do you have the pieces so that i could make the 35/40?? If not what exactly do i need to that??

Thanks again you guys for all the advice and pointers. Good to know that the rb community wont completely shun a 25 noob.

[Cjmartz2k]

Turbine wheel and exhaust housing from a HX35, center section from either, compressor cover and compressor wheel from HX40. Probably going to have to wind up buying to seperate turbos. No need to get the 6/7 blade HX40 compressor either. The smaller 8 blade flows enough to get choked out but the HX35 hot side as it is.

BTW, you could do 500rwhp with the 7 blade HX35 if you turned the boost up enough.

[Carl H]

skip the pfc if you can...after playing with a few of them i have decided that the extra resolution that they offer isnt worth it.stock ecu is the best route followed by a good standalone...i have my doubts about the aem.

[eh?]

skip the pfc if you can...after playing with a few of them i have decided that the extra resolution that they offer isnt worth it.stock ecu is the best route followed by a good standalone...i have my doubts about the aem.

Doubts about what? The biggest issue was with the ems having trouble reading some CAS, they've since issued out new CAS trigger wheels for free. Autronic has the same sort of wheel for the RB too. It's clearly not just a aem problem. It's been a few years since then and no more issues. I have't seen or heard about anyone having any other real issues. Lots of hondas running around with the aem and just about all dyno shops can tune the aem.The interface is simple and there are a s*** load of sensors you can use. Knock control/ EGT control/ boost control/Wide band closed loop/ traction control/ 2 step/ over boost protection/ onboard high speed logging... I can go on and on.It just takes a little bit of research to see how powerful it really is.

[MATTs14]

Ok guys ive got a dumb question,

What driveshaft am i gonna need if i plan on running an rb25 with the r33 crossmember and rb20 transmission?? Will i be able to use the stock 2 piece since im using the same transmission???

Thanks again to all you guys.

Also what should i use to tune the ecu after the reprogram by carl, or should the carl tune be accurate enough?? Thanks