I recently boosted my rex to 8 psi, but i am not reaching full boost until 4000-5000 rpms, i expected turbo to spool instantly. What could cause this slow spool? Please help.
Also how many horsepower would my setup max out at, say 22 psi?

here is my setup
b18a1 ls
8:5:1 compression
pistons/rods
rev hard cast manifold
Garrett T3/t4 .48 exhaust .42 intake turbo
3in downpipe and thermal exhaust
450cc dsm injectors
blox intake manifold

-----230hp 200ft/lbs torque at 8psi----

 

there can be numerous situation causing slow spool up, what ems are you running?

one i might can think of is your too rich causing slow spool up.

22 psi? with 450cc injectors your limit should be around 300hp. I'm not sure how much airflow can a .48 exhaust can flow for 300hp.

 

what wastegate? I had the same problem and found i was missing the fire ring on my Tial 38mm.

 

that turbo would max out before 22psi most likely.
I thought the .42/.48 is a straight t3 turbo?
That turbo should reach full boost pretty fast on your ls

 

I used that same turbo on my old D16 setup and I seemed to max it out at around 16psi, the graph below is at 16psi and I was only using a 2.5" exhaust. Not sure how it compares to your car but hope it helps.

 

When I dyno'd my d16 with that turbo the first time, I hit 6psi just before 4k, but I also had a cat & stock-size b-pipe and axle-back. It was also a 'sinktrap' mani made from 2" pipe, elbows, and an OEM DX 4-1 iron header...

FWIW, on my sedan, the D16 hit 10psi just before 4k as well, and that was a t3/t04b s-trim using a full 3" turbo-back, no cat, and an HF manifold.

I would highly suspect its a boost leak somewhere. Either in your chargepipes (but I doubt since its hitting 230whp), leak in the exhaust, or leak through the WG. Either would make the turbo spool slow, and that turbo should spool much faster. I've seen a B16A spool a 60trim T3 w/.63ar faster than your B18 does the smaller turbo...


As far as that turbo goes, it will push the most air at 19psi, measured in the turbo. I'd guess a normal FMIC would give you 1-3psi of pressure drop, meaning 16-18psi at the most.

 

check your chargepipes, or anywhere else for boost leaks

 

Ok i just bought new t-bolt clamps today and torqued them down very tight. But im still having the same problem. If I start out in first and shift at rev limit (7000rpm) the turbo doesn't reach 8psi till 4500rpms. It sounds like my BOV might be letting pressure out early, I have a Turbonetics Raptor. Im afraid to tighten the bolt to tight so it doesnt blow off, does anybody know how far in threads the bolt should be in? How do i adjust it and know when to stop? Also could be the wastegate (38mm tial), the top hole on the wastegate is not plugged. Would this make any difference?
Thanks for info on turbo by the way. If i upgrade the injectors could i reach over 300hp, or would it even be worth it?

 

the top hole doesnt need to be plugged. it is used if you are using a boost controller that uses that port.

 

ok didnt think so. On that boost controller subject, is it possible to tee the boost controller into the botton line on the wastegate? I have never seen it done but my tuner hooked it up like that once (I took it off to run lower boost until i get a better clutch). Would it work at all?

 

i checked for leaks everywhere. Wastegate and exhaust and intake are good -no leaks-
I'm starting to think it could be my Blow off valve (turbonetics raptor) possibly, but i dont know how to adjust it properly. Any help? Any other suggestions?

 

I have same wastgate tial 38mm. What is this fire ring?

 

i am running uberdata / crome. I dont think its the tune causing this problem (hope not). It runs slightly rich usually around 12.5 decently tuned.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by axxicution &raquo;</TD></TR><TR><TD CLASS="quote">I have same wastgate tial 38mm. What is this fire ring?</TD></TR></TABLE>

It fits into the bottom of your wastegate.

 

this setup sounds familiar...was it down at 1320? who tuned it? what do u mean UD/crome? why is power dropping so early, its not the turbo, the graph is squiggly after 5k?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by axxicution &raquo;</TD></TR><TR><TD CLASS="quote">
I'm starting to think it could be my Blow off valve (turbonetics raptor) possibly, but i dont know how to adjust it properly. Any help? Any other suggestions?
</TD></TR></TABLE>
I again had the same problem with leaking boost through my BOV(not sure if you are or not) but I was using a cheap eBay type RS and was tuned for 16psi but I would only build 8-9psi. The way I adjusted mine was just tightening the screw a little bit and then take it for a run, but going easy on it first to make sure that it was releasing enough and then once it was, I looked at how much boost I was building and determining if I needed to make any more adjustments. After that I was seeing 16psi on my SOHC with a log manifold and only a 2.5" exhaust by about 4500rpm in 3rd gear.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LoseRPunKx182 &raquo;</TD></TR><TR><TD CLASS="quote">this setup sounds familiar...was it down at 1320? who tuned it? what do u mean UD/crome? why is power dropping so early, its not the turbo, the graph is squiggly after 5k?</TD></TR></TABLE>

That graph was actually for my old SOHC setup and yeah it was not the nicest thing and couldnt really tell you why it got squiggly, but it was still fun.

 

Here is my dyno graph

Yes the car was at 1320.... Is this John? I saw the " I tune in PA".



Modified by axxicution at 5:36 AM 11/23/2007

 

no im actually the asian kid u saw walking joe through crome haha one of the first days it was there. what did the a/f look like? the graph looks pretty smooth. not bad on 8psi and low comp pistons

 

Oh yeah I remember you lol. The whole shop kinda fucked me over on the car. Joe didn't even tune it, someone else did. I just found like 6 bolts on my turbo and intake manifold they had loose, and my wastegate wasn't even tight when I got it back. They said that they cut down my spring from 13 to 8psi, but I fixed the bolts and now its running 12psi so I dont think they did. It is still spooling slow (although alot better), i see boost by 3500 now, reach full by about 4 grand or so. Does this still sound slow for my turbo? When should i start to see boost, and does it matter what gear i am in?
oh yeah the afr stays around 10-13 usually under boost, 11.5 prolly average. Should i crank up the boost to lean it out or not?

 

your BOV sounds like junk.

Also, put a boost controller on that thing, and it'll build it quicker.