lack of power above 6500 rpm on rb20det

[blues14]

I recently converted my rb20 from an auto to manual. I was driving it the other day and noticed that the car has really no power above 6500 rpm. the car still revs to 7200, but there is no gain or loss of power or speed after 6500 rpm. what could cause this? the engine has about 36,000 miles on it. I am on the auto ecu, so i borrowed an actual 5spd ecu from my local speed shop and the car drives a lot better but still has this problem. any ideas?

[Joe]

is this a recent power loss? or has it always been like that?

the RB20 dosent have the best turbo out there so dont expect it to pull as hard all the way to redline

id also look for boost leaks, whats your pressure doing at higher RPM? losing boost?

[Yellow4g63]

Yeah that stock turbo blows donkey ballz and the stock cams like most cars power starts to fall off after 6200. Cams will raise that but you will lose a lil on the bottom.

[Carl H]

welcome to the world of stock engines.get a new turbo and some cams then tell me it doesnt make power up there.

[Slo_240sx]

Sounds like a slipping clutch...Does it ping or backfire at all? I'd check timing first and then check fuel pressure. Also like everyone else said check for boost leaks. If those all check out Then I just say you need more power.-Alex

[blues14]

well, the clutch is brand new, , boost stays at about 10psi, i am using a walbro 255 fuel pump, kn intake, 3'' downpipe and 2.5'' hks catback. I am thinking the culprit may be my 163,000 mile stock cat converter. maybe it just cant flow that much air. anybody selling a testpipe??

[biglipzit]

stock cat with an hks 2.5 inch cat back? You could seriously build up some dangerous back pressures that could cause this lack of power. I would get rid of that cat. The already small stock turbo has enough trouble without that much back pressure building up.

[Carl H]

or its the fact that its a stock engine with stock turbo and cams.trust me, fit new turbo and cams and enjoy the 8k redline.

[Valley]

he said once he hit 6500 rpm the car no longer gained speed, i would assume this happens in every gear, so its not because of the engine being stock.... is there an odd noise coming from your exhaust?

[biglipzit]

Hmmmmm what ECU are you using? The auto rb20 has a different ecu to the manual and since autos dont use up all the redline and shift just before it most times maybe your ecu is programmed to not stress the transmission too much and since it doesnt need much after 6500rpm then there is no need to have the ecu programmed for performance above 6500rpm. That could be your prob if you are running an auto ecu. Auto engines normally have less HP than their manual counterparts also.

[rbsileighty]

If you are not gaining speed past 6500... I would agree with driveline problems being the reason.

You don't need a new turbo... get a testpipe (some decent shop with a welder can make one) or highflow cat and you'll see increased boost and power.

Like yellow said... the RB20 falls off around 6200 on stock cams. If you want to build significant power past here pick up some poncams from tomei and get some cam gears while you are at it to make the most of it.

Again... no need to dump the turbo unless you are getting a death whine from it. Instead use that money to get a set of brakes if you don't have them.

As for the ECU... I'm on a auto ECU (manual trans) and it runs like others I've driven with similar setups and a manual ECU. You might try switching back to the auto just to see if it was reseting it (unplugging it) that made things run better.

[Eikon]

blues... my car is exactly the same. Exactly.

I get a nice surge of power from the turbo from about 3500 to 6500... after that I might as well shift because I get no increase in power at all.

I know my problems though at this point. I have a very very poor restrictive downpipe, and the stock 160k cat still on the car. I hope to replace those items very soon.

You will want to get a 5spd ecu for your car. You said the automatic redlines at 7200>... The 5 spd is 8000k.. that's the beauty of the RB20... you should take advantage of that.

[WDRacing]

Bad turbo, smaller runner exhaust manifold, old as hell cat, stock cams...Definitly will cause a problem at higher revs, he's gaining speed he just doesn't have the pull. The lack of pull would be caused by a lack in torque, which drops off like a lead weight at anything over 6400 with stock parts. The motor can't breath, you'll never see high rpm pulls without opening up your exhaust system and getting rid of that tiny T3.

Swap in a T3/TO4E and you'll have enough volume to flow 450WHP with no lag problems. Get rid of the cat...install a new one or use a test pipe. And have a set of cams made up at Integral, they quoted me $350 for a set of regrinds. Increase the lift and add about 8-10* of duration and you'll be able to pull all the way to 8000.

WD

[blues14]

thanks for the advice. I do have r32 brake upgrade and you can really feel the difference. I will soon buy a test pipe and see if that helps. my local shop is burning some ecu upgrade chips based on the mines ecu. they are dyno testing it in a few weeks and i am first inline:) I have a mag with a 300z that makes over 1,000 whp on 2.5'' exhuast, so I think its good enough for my rb so the stock redline on the mt rb20's is 8k? I was not aware of that. thanks again guys!

[WDRacing]

They'll pull to 8000 before having to redo the valvetrain and worrying about balancing the rotating assembly. I've seen them pushed to 8500 on occassions, but those were with 264 cams a huge turbo's. So no boost at all until 5800 or so.

WD

[blues14]

I figured out my problem with 13 bucks and 5 minutes. I changed my fuel filter to a z32 filter and now it pulls to redline. the guys at the nissan dealer told me the only difference between the ka an z32 filter was their size. BULL$*#%!my filter was supposedly changed at the time of the rb swap,, but maybe not. thanks guys.

[Carl H]

uh the filter is the same, just larger.ive seen some nasty crap drain out of fuel filters so a clogged filter doesnt suprize.

[SeVa-S13]

uh the filter is the same, just larger.

Dude whatever, everyone knows the Z32 filter actually has a mini fuel turbo hidden in it that makes power at ricer revs.

[Slo_240sx]

LoL. Make sure you have a high flow fuel pump to go with that new fuel filter or you'll be blowin stuff in no time going to 8k.-Alex

[Carl H]

LoL. Make sure you have a high flow fuel pump to go with that new fuel filter or you'll be blowin stuff in no time going to 8k.-Alex

dont have to worry about that man, the tomei gtr fuel pump i have in the rear makes more noise than the engine does and its covered in carpet and i have full interior!

[Slo_240sx]

Just checkin bro I don't like it when people are pissed because they forgot something or because we forgot to mention it. People don't blame themselves anymore they always like to point the finger. Remember, when you point the finger at someone, theres 3 pointed right back at you.

[Yellow4g63]

Just checkin bro I don't like it when people are pissed because they forgot something or because we forgot to mention it. People don't blame themselves anymore they always like to point the finger. Remember, when you point the finger at someone, theres 3 pointed right back at you.

lol that flow chart is the best.