Why is my RB25 making such low torque?

[Iam99x]

Hey, guys. I went to a dyno day last month, and pulled 300 hp, and 242 tq. I've been told that my timing is off, but I've checked it, and it's right on. My spark plugs are in good condition. I can't figure it out...

S1 RB25DET
Garrett T3/T04e
Tial 38mm wastegate
HKS Super Sequential BOV
Blitz FMIC
Nismo Fuel Pressure Regulator
Greddy Profec EBC @ 10psi
The car has not been tuned, yet, and I think that it should still make more torque even untuned. I may be wrong.

Any help or suggestions would be greatly appreciated.

Thanks,
Allen.

[l0nestar]

What are the specs on the turbo. Numbers appear to be believable. DO you have a copy of your Dyno chart?

[Zacho2]

Honestly I wouldn't even worry about #'s until you get it tuned.

[Iam99x]

What are the specs on the turbo. Numbers appear to be believable. DO you have a copy of your Dyno chart?

It's a .60 trim.

Honestly I wouldn't even worry about #'s until you get it tuned.

True, but my friend has a S2 RB25 bone stock that dyno'd 276 hp and 276 tq on the same dyno. Stock turbo running like 10psi or something.

Here are our videos if anyone cares to watch for giggles:

Me:

[youtube]http://www.youtube.com/watch?v=7B9YhCEWZqs[/youtube]

Neejay:

[youtube]http://www.youtube.com/watch?v=rN7wpZI5I68[/youtube]

[l0nestar]

What are you using to tune with? PFC, Nistune, AEM, MS?

That .60 should be able to net you solid 300's, but agreed, get it tuned first, then start looking at charts. Also, what AFM are you using?

[eh?]

That's Normal.
You should NOT be making the same TQ# as HP. I would bet those with similar TQ# and HP# are having boost spikes/ bad tuning/ other problems. Remember you have a short stroke engine. You Will have low TQ.

[Iam99x]

What are you using to tune with? PFC, Nistune, AEM, MS?

That .60 should be able to net you solid 300's, but agreed, get it tuned first, then start looking at charts. Also, what AFM are you using?

I'm going to use an SAFC-II. I have the factory AFM on there now, but I have a N62 that will be on there when it gets tuned.

That's Normal.
You should NOT be making the same TQ# as HP. I would bet those with similar TQ# and HP# are having boost spikes/ bad tuning/ other problems. Remember you have a short stroke engine. You Will have low TQ.

All of the semi-local RB25 owners that I know of are making right at the same torque as they are horsepower. One guy is making 411 hp and 405 tq.

[240z4u]

I know NOBODY with a well sorted car making same tq as they are HP.

[l0nestar]

your maxing out your AFM.

I agree completely with what eh? said.
I would much rather have more torque than HP, but it's futile on this engine, lest I do some serious tuning. If your torque is 65-75% of HP, that sounds reasonable. Again, charts will tell the tale.

[Iam99x]

I know what the dyno sheets say, but okay. You guys know better than I do. Anyway, you really think I'm maxing out my AFM even on 10psi? Are they really that s***?

[l0nestar]

Yes. I used to max my OE RB25 AFM with the stock turbo @ 10 PSI. That is the main reason I upgraded to a Z32 AFM.

Post your chart. Does it include A/F readings?

[Iam99x]

Yes. I used to max my OE RB25 AFM with the stock turbo @ 10 PSI. That is the main reason I upgraded to a Z32 AFM.

Post your chart. Does it include A/F readings?

Gothca.

I'll post it up tonight when I get home.

Thanks, Guys.

[Iam99x]

I can't find the damn thing, but here's a pic of it that I took a while back. It's a little blurry...

Let me know if I need to keep searching for it for a clearer picture.

[meet07]

whats up with that dip?

[Iam99x]

Good question.

[FinkenS14]

What are you using to tune with? PFC, Nistune, AEM, MS?



I'm going to use an SAFC-II.

You fail

[Iam99x]

SAFC-II isn't the best in the world, I know, but it's better than no tune at all. It's all that I can afford right now. My long term goal for tuning is going to be Nistune.

That dyno sheet is from the dyno run in the video. You can't notice that sudden dip in the powerband while driving or on the video. It's odd.

[GSDKinked]

SAFC-II isn't the best in the world, I know, but it's better than no tune at all. It's all that I can afford right now. My long term goal for tuning is going to be Nistune.

That dyno sheet is from the dyno run in the video. You can't notice that sudden dip in the powerband while driving or on the video. It's odd.

I'm going to tell you this right now. If you can't afford it, don't bandaid it. It will make things worse. Just save and save and then get it. Proper tuning will save your motor from grenading. Unless you like blowing s*** up

[240z4u]

Beware of that turbo BTW. I had the same turbo as you and had serious compressor surge problems above 12psi. I had to replace it.

[ST240]

You fail

Cmon man. One of the reasons I like this forum is because posts like this are rarely seen in serious discussions. Nico has been pure gold for me for a lot of things and I don't want it to go down hill like my local car forum has.

I'm not coming down on you at all but it would be great if you could tell him why he "fails" instead of just posting that. No offence meant man .

[Justin Duncklee]

^ I think he's saying you fail becuase the other guy listed off all these nice standalones; PFC Nistune, AEM, ms, and the guy is using a SAFC

[GSDKinked]

You fail

Cmon man. One of the reasons I like this forum is because posts like this are rarely seen in serious discussions. Nico has been pure gold for me for a lot of things and I don't want it to go down hill like my local car forum has.

I'm not coming down on you at all but it would be great if you could tell him why he "fails" instead of just posting that. No offence meant man .

You gotta realize the person saying it wants to put a T28 (From an SR) onto his RB set up....

[l0nestar]

You fail

Nested comments appear to beyond your comprehension. <insert terse retort here>

[s13drifter88]

Those numbers honestly look legit to me. the dip may be the maf hitting 5 volts maybe idk. g60 i think which is good to 300-310whp on rb25 tho Im not entirly sure tho as i have a ca so dont flame me if im not on point. If you have an afc it will be okay to use it to cal in an n62 maf but then u could start pushing ur fuel system past its limits. afc also trick the computer by modifying air flow signals so telling the comp ur getting more or less air will make u run more or less timing. the computer itself can run ur stock injectors to their 370cc max so u cant really use it for "more fuel".

[Iam99x]

Thanks, everyone. I hope my turbo will do fine after the tune for 14psi.

Should I sell the SAFC-II and save for Nistune and a tune?

[s13drifter88]

to my knowledge there is no nistune for rb25 computer, u have to use a z32 tt computer and re-pin the wiring harness main plug to use nistune tho i could be wrong and something new having been released that i dont know about. either way, id sell the afc and look into something different. safc is good to cal in a different maf and make some SMALL corrections but not for anything serious

[ST240]

If the maf was hitting 5v it wouldnt continue making power after that would it?

Yeah with regards to nistune, you can use either the Z32 ECU in order to retain VCT, or you can use an RB20 ECU but youll need a VCT controller should you choose to retain it (and why wouldnt you?). I think theres also a TPS mod you have to do as well with the RB20 ECU...

You're able to browse the Nistune forums, but you are unable to post unless you've bought it. I'd suggest going on there and learning everything you can .

[Neejay]

That's Normal.
You should NOT be making the same TQ# as HP. I would bet those with similar TQ# and HP# are having boost spikes/ bad tuning/ other problems. Remember you have a short stroke engine. You Will have low TQ.

Yeah, when I made that much, I was actually kinda worried. And still am, which is why I granny my s13. lol I still need to tweak my setup. I'll be using a SAFC2 + N62 MAFs tune for a while. Why? Because my motor is stock, with the exception of a Apexi cone filter and 3" turbo-back exhaust. I'll also be buying a wideband o2 setup as well.

When/IF I upgrade the turbo, injectors, etc., I'll go with a NISTUNE setup.

[s13drifter88]

That's Normal.
You should NOT be making the same TQ# as HP. I would bet those with similar TQ# and HP# are having boost spikes/ bad tuning/ other problems. Remember you have a short stroke engine. You Will have low TQ.

This is an RB25... not an RB20. It prob made similar tq to hp being the stock turbo and it comes "on song" where the motor is right in its power band where your larger turbo prob has a little bit more lag so when u do acheive full boost ur not utilizing the full potential of your rev band. I can see an rb20 making 265-270whp and 215wtq in stock form but its no surprise to see a stock rb25 do 280whp 265-270wtq. 500cc more displacement with a slightly larger turbo and VCT, theyre not a tq deprived motor. i raced my friends rb25, him on 10 psi me on 12 and i had my hands full till about 3ed where my turbo took command.

[eh?]

1) the rb20 rb25 AND rb26 all have very short strokes. You need to research under and oversquare motors and their torque characteristics before you talk about displacement.
2) vtc does NOT increase maximum Torque. I have shown a dyno of the effects of vtc on and off. It only helps mid range but NOT max. That is exactly what nissan says it does.
3) I have done enough dyno tuning to see the effects of boost spikes/ creeps on the rb25. How much rb tuning have you done?
4) lastly the rb25 makes 250hp/213tq. Why would you think a larger turbo would help tq than hp?