SleepingTalon

Actually, the ball bearing will offer faster spool than the journal bearing based on its design. Ball-bearings use less oil and handle pressure more efficiently and effectively than journal bearings. Journal bearings run on a film of oil and the shaft relies on a constant supply of fresh, clean oil over a very wide contact area. The frictional value is very high on a journal bearing design. The 2 big options offered to most of us is the 270 and 360 degree bearing on the journal bearing turbos. The difference between the 2 is the the 360 has a full circle of lubrication, six orifices on the washer instead of three for the 270. The ball bearing design, althought it's still fed a small amount of oil, doesnt rely on that thin film of oil to support the shaft. This is what allows for the faster spool. Hope this helped some...

In the USA, we use what I think you would consider anywhere between 96-98 RON at the gas station pump. I dont know how you measure race fuel, but what I stock is 117 PON, unleaded. As far as the build goes, according to my measurments, there are 2 different bore sizes in the block. I dont know why that is, but it is infact like that, so I'll deal with it. On top of the factory pistons, there are some markings with 2 different numbers. Some pistons say "05" and some pistons say "06", and those happened to be the different bore sizes. I'm gonna bore the block .020 over to fix this anyway, so it's not an issue. Of course I'll be honing as well, as I always do that when I put new pistons in a car. I also grind down any sharp edges on the tops of the pistons to prevent any hotspotting. With the addition of the GTR rods, I'll be balancing the entire assembly as well. All in all, it should be a pretty strong motor. I really wish we could throw a set of cams in, but with this being a drift car, he really doesn't want it to overpower what it's being used for. If this was a drag car, I'd be knife-edging the crank, and using aluminum rods, but for 300-330rwkw, it's not necessary. It's not always necessary to balance the assembly, as I've built motors and just put pistons/rods in, with just some ball honing, and they were fine, but I'm gonna take the extra step with this one. This is a similair build to the Dodge SRT-4 that I did awhile back, with the exception of the Dodge having a built head. I figure with the use of race fuel, a heavy duty bottom end, and headgasket w/headstuds, I should be able to run a good bit of boost. Does anyone have pictures of the GTR rod next to the GTS rod? What's the difference between the two? Is it visibly bigger and a heavier rod? I'm just curious as to what's actually different between the 2 pieces...thanks!

This car started off as something small, and like most, has turned into something much larger than anticipated. Thanks to this forum though, things have gone smoothly. Rods/Pistons are being fitted so that the motor can sustain more boost and a more aggressive tune. The head will remain stock, with the only exception being a new headgasket and ARP's. The 2540 will be the turbo he's using, although it was not by choice. The customer purchased many of these parts with the car, so we're making the best of what he already has. If it was up to me, we'd be using a GT30R with the larger A/R housing. Anyway, fuel tuning is done with a SAFC2. It's got stock timing in the car, although with the SAFC2, it's not uncommon to see more aggressive timing numbers due to the way it adjusts the a/f mixture. It's fitted with a walbro fp, SARD 550cc injectors, and a Nismo AFPR. I'm going to leave the boost at 18-19psi on pump gas, which is 93 octane here. Normally, anything above that on that grade of fuel will cause knock. I will up the boost and build the 2nd data file for race fuel. How much boost extra, I'm not sure. I wont know until it's on the dyno and Im able to monitor everything. It's a fun build process, and I can't wait to get to the final product. I'll be sure to post all the results as I go, not that you guys haven't done what I'm about to do more times than I can count! LOL. If anything, I guess it's good to have the extra data on the site.

Yes the dyno we use at the shop is a dynojet. However, as I said above, we do have a dyno dynamics dyno here too. Infact, it's only about an hour away from the shop. While the dynojet was being installed, I dynoed a WRX over at the dyno dynamics dyno (www.dyno4mance.com), and the car made 253awkw. A few weeks later, after the dynojet was delivered/installed, we put the same car on the new dynojet (www.batlground.com) and it made the EXACT same numbers. I was sure it was gonna read higher, but it didnt. Needless to say I was VERY suprised. I've always been under the assumption that the dynojet read high, but in my ONE experience in testing this theory on the same car, the numbers were the same. I also put my new Audi S4 on the dynojet, and when comparing it to other dyno plots from other people who use different dynos in the USA, I noticed that my numbers for my S4 are lower too. I guess the true way to test this theory is to go put my S4 on the dyno dynamics dyno, and see what numbers I get, but that'll have to wait for now. As a tuner, I dont really care about numbers. All I care about is repeatability. I mentioned above that the dyno dynamics dyno's have a load control on them, and I wouldn't be suprised if that had something to do with the number repeatability between different dynos. Who knows...

Does anyone have the correct part number for the rod bolts because the part number (ARP 202-6005) I found actually corresponds to the SR20, not the VG30. Is it the VG30DET or VG30DETT? There are 2 different part numbers listed in the ARP catalog for those 2 motors. Actually 3 different part numbers if you count the SR part number I listed above. Any rod bearing recommendations, and a good place to purchase those from? Thanks again!

Which bearings do you use when fittings these rods? Do the old wristpins work, or is there another way they need to be fitted? Do ARP's work on these rods? Any other specifics would be greatly appreciated. StageZilla, I just talked to my customer and he would like to purchase the rods from you, so it looks like you sold a set! Thanks again!

Are the GTR rods direct bolt in, and are there any fitment issues with the rod bearings? If not, where can I purchase those? Is there anything else that needs to be done to fit these rods into the motor?

I will call him tomorrow about it. I'm pretty sure he'll do it. I totally agree with all of you, as there is no point to not doing it the right way when you already have the motor apart. So the stock rods shouldn't be taken above 300rwkw, even with forged pistons? I guess that's what others have experienced as the limitation of them. So I assume that everyone here would say that 522rwkw on the standard motor isn't conceivable? At least, I dont think it is...

That's a very good point. The reason I haven't added them to my build list is because I'm building the car for a customer, and it's not my choice. The ringlands busted on 2 of the pistons, and that's why we're putting new pistons in. Where can I source GTR rods? Thank you, I will make the suggestion to my customer. Sourcing Skyline parts in the USA isn't the easiest task in the world, which is why I frequent this board. The car made 295rwkw at 19psi with an HKS 2540. The rest of the motor was stock, but with the pistons coming apart, it's time to upgrade.

Well, even with all things being equal, conditions being optimal, and having a good tune on the car, I just dont see it holding up for that long. I see some people saying that 375rwkw is fine, but never from someone who actually OWNS and RB25, lol. Most other people have had the same experience that I've had, with that being a 300rwkw threshold for the standard bottom end. A rod that snapped at 278rwhp seems to be a possible tuning screw up. That number is real low for the motor to come undone without there being error on the tuners part. RB26 rods are pretty damn strong, but the pistons are also not quite up to the job of HUGE hp demands, correct? Meaning, from my experience, they're not quite on the same level as that of a supra, which can make 600rwkw on the stock bottom end no problem.

I'm actually wondering the same thing. I'm gonna be assembling a bottom end with a set of Wiseco's and the stock rods, so I was also curious of the limitations on such a setup. I only revved the motor to 7k during the last tuning session when it made 295rwkw, but I didnt think the stock motor and valvetrain was capable of anything more...Visibly, the stock rods dont look to be weak. The wristpin is pretty big, and their pretty short and stubby due to the stroke, but in this game, "visible" strength doesnt hold any water in comparison to ACTUAL strength, lol. Anyone else have any input they can share?

I was just wondering because someone had commented to me about a bone stock RB25 making 522rwkw, and based on my experience, I just dont see it. As far as the dynos go, well, I've always heard dynojets read higher as well, but from my one experience I've had, they read the exact same. The link to the dyno dynamics dyno I used can be found at www.dyno4mance.com. The link to the dynojet I used can be found at www.batlground.com. Like I said, there is a load control on the dyno dynamics dyno, so I dont know if that plays a role in the number repeatability, but that's only a guess.

587rwhp is quite impressive! Do you have a link to this car? I've never heard of an stock RB25 motor making that kind of power...I'm curious to know how the pistons held so much power. Do you have any idea what kind of setup, and how much boost? What kind of timing numbers? Any info or a link to it would be greatly apprecitated. Also, if anyone has seen a factory RB25det with HUGE power numbers on the standard motor, please post. I do believe 587rwhp is the most I've heard of...

LOL, that's exactly what I thought! There's just no way that standard bottom end will make that kind of power. I've got a few boxes of busted pistons that are a constant reminder of that small fact! My question is this though, what's the most ANYONE has made on the standard motor (with just headstuds and a headgasket, but standard pistons/rods)? Has anyone been able to make 400rwkw? I think even that would be far fetched as well...

How much is considered high rpm? 7k...? I'm about to put a set of wiseco forged pistons on the standard rods, and then increase power to roughly 320rwkw on race gas. The car will stay at 290-300rwkw for daily driving, but make 320rwkw for track purposes. Has anyone gone a similar route with their setup?

Actually, we have a dynodynamics dyno here in the states, and we tuned a WRX over at the dynodynamics dyno while the dynojet was being installed. The car made 340whp on the dynodynamics. When the dynojet was finally installed, the car made the EXACT same power on the dynojet. I was sure the dynojet would read high, but that wasnt the case. I think it's all based on how you adjust the load control on the dynodynamics.

That's exactly what I've come to realize about the standard pistons. What about the rods? The rods look strong enough to handle a fair bit more, but I still think its a far cry from 522rwkw! I just dont see anyone being able to tune the standard engine to that kind of power levels. With forged pistons and aftermarket rods, then I can see it, but on the standard internals??? I dont think its been done. What's the most anyone has seen the standard motor make? Has anyone been able to make 400rwkw on the standard bottom end?

I've tuned them on the stock motors to 290rwkw, but the motors longevity wasnt there. 522rwkw seems a little overboard though. I've noticed that the pistons arent up to the task, does you or anyone else have the same experience with the pistons being weak? They are a cast piece, not forged.

Can anyone verify that the RB25det can make (522rwkw)700whp on the stock motor, no problem? I've had this "rumor" thrown in my face, and I wanna verify the "extreme" limitations within the largest group of RB25 owners I know of. Can everyone with experience, please let me know? By the way, just so noone has to look up the conversion themselves, the conversion from rear wheel horsepower to kw, would be 522rwkw! Is 522 at the rear tires feasible on a standard internals of an RB25det? Thanks again!

I have a question that I thought some of you could help me with. Im a tuner in the U.S., and I recently tuned a few RB motors, both of which made EXCELLENT power. Anyway, the first one was an RB20DET, it made 350whp (261rwkw) @18psi on pump gas, that's 93 octane here. The one I did last night was the RB25DET, and did even better. It made 395whp (295rwkw) @19psi on pump gas, 93 octane. My question is, how much boost do these motors take without the need for headstuds? Is 21psi safe on the stock head bolts? Does it need a upgraded headgasket with some ARP's? Also, how much power will the stock motor, on each of these platforms, make before having to upgrade the bottom ends? Lastly, how much RPM can you spin on each of these motors with the stock valvetrain? On a final note, both of these engines seem to make power with ease, and are great platforms from what it looks like to me. It's always fun to play with a different platform and see what it can do! Thanks again everyone!