s13-rb20:Dyno run II

Well finally went yesterday and did my yearly. Not a pap-smear, but spun the rollers. kinda dissapointed,but not really as my hp goals of 300whp haven't yet been realized on paper. But are there in reach.

Got a full tank of 93 oct, but the car still wasn't fast as it usually is. Thinking they sneaked in some ethanol into the mix. wanted to go to columbia and get some 94 oct just make sure it ran like a champ. But that didn't happen. adjusted my boost controller as it reads 2 psi higher than really is. so it was 15psi i started out with..


https://www.youtube.com/watch?v=p5VV_B25_V4



final number was 243.37@229.48tq
last year was a sorry ass 184.55@165.39tq

my problem this time was my boost wasn't steady. on my final run(this one) he hooked up a boost gauge to tell me where i was at.

got up to 15psi,dropped down to 0. got up to 16psi,dropped down to 0.got up to 18psi,dropped down to 0.???

so the dyno guy said my porfec b settings were bad AFTER i did my final run. i did set the gain "only' to 35 and i didn't adjust anything else.. so sperm on my face for that mistake.

if that wasn't the issue it could be

-the damn hx wastegate,since it dosen't have a ref bung on the cold side(i made one on the intake charge pipe). that could be it. and ive heard that the stock internal wastegates on these are funny.

-boost leak. dosen't seem likely since i have everything t-clamped(not t-bagged). but one or 2 of my pipes aren't lipped.

so there it is. the dyno guy did say cause i was dropping off and i didn't have a steeady boost curve that i was missing 50hp.. so next year iam going for goal..
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240sx guy. you were right on controlling the wastegate???

I love dump runs! Well not where you want it, but it is a start . Would the drop on boost be a leak in some point?

Mike

it could be, but if it was a leak the psi wouldn't rise higher and drop 2 0 and rise again you wouldnt think??

Id check your wastegate, it might be a good idea to tap into the compressor housing instead of the charge piping

Overboosting wrote:

Id check your wastegate, it might be a good idea to tap into the compressor housing instead of the charge piping

This. ^


A good way to check for boost leaks would be to use a leak tester like this one:



I want to Home Depot and bought parts for mine. I didn't plug the one end off like they do in the video..... mostly because I wanted to check everything down to the lower intake. Sometimes you can't hear the leaks, so just use a bottle of soapy water and look for the bubbles. Nobody that owns a Turbocharged vehicle should be without one of these.


With boos dropping to zero and then back up, it could be the wastegate. How fast was the drop/recovery? Sometimes a boost leak won't open up until a certain pressure....



Good luck man, you have a good start!

the drop and recovery was pretty quick, so tapping into the cold side is easy as drilling and welding??? i will have to do this boost leak test kit. i was also told that the stock bov would also leak at a certian psi..

Do you have a video of the boost gauge or did you log boost? Was the needle oscillating at the same area every pull? Compressor surge sounds like "ch,ch,ch,ch" almost like sneezing rapidly under WOT. My old t3/t4 setup did this and I had to change to something else because of it.

You may have a hole in the diaphragm of the wastegate, or the line running to the gate is too long and is creating a lag in correction if that's not it.

I expected to see severe boost creep, but forgot you had the 30 not the 35 on your motor.

no i have a graph of the boost that they logged on the dyno.

so the line running to my wastegate is going to the profec. you are saying if thats too long it could cause problems?? what about the bov??? i put the stocker back on..

https://www.youtube.com/user/synaptic1#p/u/29/oIAVLG2nh_U

Profec b has underhood solenoid for acutal boost control right? I am wondering if those lines are too long. Very easy to check obviously. Let's see the maps of your boost.

If you want to eliminate the bov as the problem, plug up the hole and remove it completely just for testing purposes.

I don't think it's the boost controller since it can only raise boost, not lower it. The wastegate spring(line directly from boost source to wastegate) is higher than 0psi guaranteed. Something goofy is going on.

It's unlikely to be the boost controller, I agree with ^

but can't the boost controller (limit) boost???

anyone know someone selling an oem srt 4 wastegate??

supersayianjim wrote:

but can't the boost controller (limit) boost???

anyone know someone selling an oem srt 4 wastegate??

Boost controller can't lower boost any further than having the wastegate hooked directly to a boost/vac source.