I’ve had my rb25det in my 95 240sx for a few months now and still running awesome.
Just had a few questions and most problems ive already figured out just from researching around but just want some opinions and some suggestions.
I am having issues with burning lots fuel (even though it is turbo’d) and have come to the conclusion that its because of my SSQV. Because its an atmospheric bov my stock ECU is still thinking all that air its releasing when i release the throttle is still there and thus pumping more fuel then is nessesary and i dont plan on getting a recirculating bov. And also i can tell that im burning really rich because of all the backfiring. So only way of fixing it is to get my ecu tuned. I have a greddy profec-b but wanting to get it tuned before install.
Now my question is in the next year or two im going about the goal of 350ish rwhp on low boost and 400rwhp on high boost. So what should i be looking into for upgrading for fuel efficiency and perfomance wise. Example; i still need to get a wide band o2 sensor, but what about a new MAF, Power FC/EMS or just a SAFC. Also who would you guys trust to program a Power FC or what ECU would you guys suggest (pros/cons) and again who would be the best to program it.
As for upgrading, im looking for a turbo good for 400-450whp so i was looking at a GT2871R but no to familiar about what A/R to get and how much lag with either .63 or .86. More or less suggestion for 400whp.
although an S-afc and a Z32 MAF would help with tuning the fuel maps, it’s not precise, and doesn’t tune ignition timing maps. Greddy E-Manage can. the new Greddy E-manage Ultimate even has auto-tune with the help of a wideband O2, which helps in getting your car driving in no time.
Turbo wise, i would actually opt for a T3/T4E 57 trim or bigger. it would support 450 crank HP, and cost 1/2 that of a GT series turbocharger.
Ok, if you want to hit 400whp on an rb25 here’s the recipe.
Keep in mind, unless you rebuild the motor/use cams, the more power you have, the bigger the turbo you need, the more lag you will have. There’s always a tradeoff of power and lag, im running an hks gt3037s on my car (rated for 500ps) and for me its almost too laggy. Once i rebuild my motor and get cams that problem will be solved though. On stock motor a gt30r is not all that bad, a little bit laggy. A gt3071r is a good choice as long as you get the one with the bigger center section. I dont think the 2871r or 3071r come with t3 exhaust flanges though (i could be wrong, but i think u can swap the exhaust housing off of your stock turbo to the aftermarket one, or just get a t2 flanged manifold. Either that or you can run an external gated set up which is a way better idea if your making 400whp, cause internal wastegates tend to run out of flow at that high of horsepower and you get boost creep. Anyway, here’s an idea of what your gonna need.
Emanage or some Standalone with at least $500 worth of dyno time, and someone who can tune it well.
Injectors (550’s would do fine)
Fuel Pump
Boost controller (which u have)
FMIC
Intake
3 inch turbo back exhaust
FPR (good idea)
Wideband or at least a bung welded in for the dyno wideband.
Headgasket (stock one will hold, but who knows for how long, this also drops the CR cause 25’s are 9:1)
Cams (not necessary but make it a whole lot easier)
Turbo
Manifold
Wastegate
Good Colder Heat Range Plugs
Good Clutch to hold it all
Z32 MAF
Also to make 400whp on the stock intake manifold is sort of stretching it. It can be done, but at that point its not very efficient anymore and if you get a top mount turbo your pipes get heat soaked quite badly from the turbo. Greddy plenum is a good idea.
400whp is not just a magic number that you can slap a turbo on a car, crank the boost up and make that much. It takes a lot of work, and someone who knows what their doing. A 300whp car will run high 12’s on street tires…400whp will put you at like 120mph in the quarter.
And im not looking to get cheap power in anyway. I know it costs alot of money and time to get quality performance. So if it costs me another 5 grand to do things right and get a solid 400whp engine rather than some smaller turbo blown to the max. So cheap or cheap way/parts is not in my vocabulary when it comes to cars.
And yah it does sound like you know how it goes Chris.
I was looking at 650s but i was thinking its a little too much.
I already have boost controller, intake, 3inch turbo back, fmic.
Still stock turbo and everything. And ill probably be getting a new intake manifold when i buy a turbo for best efficiency. Again price really isnt a problem cause its worth it in the long run. Also if i was thinking of putting a metal headgasket, but if im doing that i might as well just redo the cams and such. But thats the only section i dont understand. Replacing the cams entirely? And what else are you doing or suggest when you have your engine open.
I also was looking into plenums but just recently starting researching them.
Another thing i am getting and installing over the winter will probably be a kaaz 2way since i still have a stock lsd on my 240.
And about the 120 on the 1/4…thats my plan haha, i more or less want to drift, but ever since i did a 8.1 in a 78 oldsmobile (passenger seat) i love the g’s. Aswell as friends with gtr’s. Even though the stock rb25 is a nice change from the ka, its still not enough anymore.
Something i forgot to ask was about gear box. I have the rb25 tranny but what about the gear box. Because lets say a gts with an rb20 can hit its govner before it redlines in 4th when im looking at 5th at 5500 rpms. Not that i care about going that fast in most places anyways, but i want to set the ratios for a track or drifting. And i do understand the drivetrain loss during a swap.
I’ve never attempted to get a car past 300whp so all this feed back is awesome, thanks guys.