dyno numbers

[HPF Chrisk]

last night i decided to dyno my car and here is the results



it is a s1 rb25det in a s13 coupe, only mods are dp, cat delete, catback exhaust, but for some reason i am only running 6 psi, and it wasnt a steady 6 it would go between 5 and 6 so i think i have a big boost leak, or wastegate accuator is broke, i belive stock is 8 psi, well tell me what you guys think

[Joe]

if you dont have your boost solenoid hooked up you only run 5.5psi.

[HPF Chrisk]

is there a differnce between s1 and s2 wastegate accuators then? becuase a buddy of mine has his wastegate accuator hooked up off a intercooler pipe just like mine and he runs 10psi with no boost sylinoid or anything like that, and he has a s2 motor

[Joe]

nope, i had a S2 with no boost solenoid and ran 5.5psi

used to creep a little but never to 10.

[garage-c]

The TQ curve is total ****... 40lb/ft drop from 5k to 6.8k rpm.

[Joe]

The TQ curve is total ****... 40lb/ft drop from 5k to 6.8k rpm.

at 5252 rpm torque turns into horsepower. thats why the lines cross like that on almost all dyno with stock engines. modified ones are a different story but since he is running a stock turbo, thats what it should look like.

thats actually good torque curve. see how nearly flat it is? thats what we call "power under the curve" its where true acceleration really comes from.

[DrifterProdigy85]

Torque curve looks far from flat IMO. Only flat spot of torque is from 3800-4200rpm, after that its a roller coaster ride. My RB25 is 6psi stock too. Put a wideband on and see what the AFR reads. Most likely pretty rich.

[l0nestar]

*Note to self, learn how to read / interpret dyno charts.*

[Joe]

Torque curve looks far from flat IMO. Only flat spot of torque is from 3800-4200rpm, after that its a roller coaster ride. My RB25 is 6psi stock too. Put a wideband on and see what the AFR reads. Most likely pretty rich.

look at the overall direction of the curve. not the exact numbers. its a bone stock engine, not something that has been tuned. he doesnt have the ability to change the maps to get the curve perfect.

this is NOT a flat curve.

[matafied]

both my s1 and s2 without boost solenoids both stay solid 7psi. yea i would def check and fix that wastegate issue, cause that seems alittle weak. my s2 stock put down 254

[HPF Chrisk]

matafied- what did you have done to your rb when it put down 254??? i am still running the stock sidemount intercooler

[blurrbosi]

Numbers seem a little low IMO... Does that thing pull then ease out then pull again?

Looks like she might be sick or you have to give her a once over.

[Kansei240sx]

Those numbers are low as balls. You more than likely have a large amount of boost leaks. Get rid of the boost solenoid, that thing is trash, run an MBC or a striaght line from your hot pipe to WG with the MBC in the middle.

Check your timing, it should be at 15 +- 1 degree.

Also, get an AFR reading. From what it sounds like, you're also running fat as hell. Leaning it out some should help.

[HPF Chrisk]

i am pretty sure i do have a boost leak, and it is running rich cause i do have a aem afr, i want to get a boost controller on there soon but i am not sure cuase i dont have a afc or anything on there and am not sure how much the stock ecu can take. i would like to do a compression test but i am kinda scared to see the results, i am going to see if i can find any boost leaks first.

[DJButton]

Check for boost leaks, check you're timing and do a compression test as well, knowledge is power, at least you'll know what's going on in it. Hopefully just major boost leaks, and if you're actuator is bad try and snag an RB20 one they go at 10psi instead of the 7psi on the 25.

[002-M-P]

at 5252 rpm torque turns into horsepower. thats why the lines cross like that on almost all dyno with stock engines. modified ones are a different story but since he is running a stock turbo, thats what it should look like.

Torque and Horsepower will always cross at 5252 rpm on every motor of every car. Horsepower is completely dependent on torque because it is nothing but a simple formula.

HP = (TQ x RPM)/5252

So, when your RPM=5252 the 5252/5252 will cancel each other out and the formula will simply be HP=TQ.

As long as your horsepower does not fall of at the end then you are fine. That is why a flat torque curve is important. It guarantees that the horsepower will continue to increase with the revs based on the formula above.

[HPF Chrisk]

i really dont think that there is something wrong with my car, becuase at 5.5 psi i put down 249crank hp if you figure a 15% power loss threw drive train, i think at 8 psi i will put down quite a bit more, maybe not 254 but each dyno reads different also. check out this s14 too

http://www.northwestnissans.co...60388

he has full exhasut and a greddy intake mainfold and at 7psi he only put down 220whp.

[Sykoperformance]

Just for comparison, here's a pretty good example of a flat torque curve. This is from a stock RB26DETT with a little bit of extra boost.

[95-S14]

I know that dyno chart

[HPFBranden]

nope, i had a S2 with no boost solenoid and ran 5.5psi

used to creep a little but never to 10.

It was my Rb25 that was doing 10lbs without any controller or solenoid. The car used to have an AVC-R but it was removed, both the boost gauge and AVCr had read 10lbs. The numbers it put down on the same day and dyno was 236whp and 203wtq.

[DrifterProdigy85]

look at the overall direction of the curve. not the exact numbers. its a bone stock engine, not something that has been tuned. he doesnt have the ability to change the maps to get the curve perfect.

this is NOT a flat curve.

This graph doesnt even show TQ, but you can tell from the boost layout and HP curve that the torque never drops which would make for a flat torque curve. Actually boost creeps toward redline some which will make the TQ curve rise slightly.

[DrifterProdigy85]

Just for comparison, here's a pretty good example of a flat torque curve. This is from a stock RB26DETT with a little bit of extra boost.

Thats a great example of a flat tq curve. Just for comparison sake heres my SR20 graph. Its not stock but shows a flat tq curve.

[Racinjitter]

It was my Rb25 that was doing 10lbs without any controller or solenoid. The car used to have an AVC-R but it was removed, both the boost gauge and AVCr had read 10lbs. The numbers it put down on the same day and dyno was 236whp and 203wtq.

I have a stock S1 rb25 and it runs a steady 10psi all day long, With the boost controller off 10psi, on 14psi.

[DJButton]

Oh man ^ I forgot about your thread in the Classic Z forum, I see you got the car running though!!! I'll have to go find some more pics!

[matafied]

[IMG][/IMG]

stock with just frontmount and mbc 10psi

[HPF Chrisk]

matafied- there is a big difference between our hp numbers because there is a big difference in the motor set up, i am running the stock sidemount at 5.5psi, you were running 10psi and a fmic, so the extra 4.5 psi and fmic is what got you the extra 59 whp. ummmm maybe? maybe not? idk maybe you can tell me.

[l0nestar]

@matafied

And that is why I am going FMIC and MBC to 0.7 bar! I can't freaking wait... What exhaust / intake was on there when you did this pull?

[DrifterProdigy85]

Matafied, Why is your AFR so lean?

[DrifterProdigy85]

Can anyone explain the bump in tq from 4500-5000 rpm?

[Bwana]

Matafied, Why is your AFR so lean?

12.5-12.8 at 10psi... looks fine to me.