Why such late boost?
 

My car made 380rwhp at 16psi on a stock motor with 50k miles. T66 turbo with a .70 divided housing. I was told that with this setup I should see full boost at 3500 but it was 4700. I have the pfc map air fuel graph and dyno graph right here if needed for reference.
http://plaza.ufl.edu/yanni25/YanniT66.zip

Just trying to figure out what the deal is before I get my new engine and upgrades in. Im also thinking about getting a bigger turbine housing because everyone tells me im choking the motor. I dont mind making only 450rwhp on some higher boost with a ported motor and having full boost at 3500. I dont want to have full boost very late unless I can make 550rwhp.

Thank you friends

waht manifold you using?

sorry I knew I should have posted that...hks manifold. Im not sure if it is divided also or if hks even makes a divided one. I will be pulling it off the car again very soon though so I can check.

guys dont get me wrong. I thought the car ran amazing and even though full boost was late it still had more pickup than my stock non seq twins in the last car. You punch it at 2k rpms and you are moving fine. I was just made aware of this by steve kan and I had no idea there was anything wrong until he brought it up. If there is a way to make more power with a bigger housing or get full boost earlier with this setup I will shit myself because I thought it was great already.

Why would you want to punch it at 2k?

Are you sure that it should have full boost that soon with stock ports? If your engine was steet ported then the boost should come on sooner. What type of wastegate and controller are you using? The wastegate might be getting the signal to start opening too soon so you aren't building full boost until a higher RPM.

First, turn the wastegate adjustment down all the
way so it can't open. Then drive _very carefully_
and hit it in 4th gear from 2500 RPM or so.
The reason for forcing the wastegate shut rather than simply disconnecting the hose it that it is possible for exhaust pressure to push the valve open.

If it's still slow, the turbine housing may be damaged. I had a 0.70 P trim with my 60-1, and wound up melting it internally. Then the boost response got much worse. I got better response
out of a 0.84 at that point (which is still holding up fine).

I don’t know to what degree this correlates to your spool up, but if you compare how your horsepower ramps up from 2.5k to 4K rpms for run 3 to that of this RX6 (which we know is fast spooling) http://www.catenet.net/graph.php?car88=1&SUBMIT=GRAPH
your numbers are very comparable.

Approximating points on the curve:

RPM (K) Your Hp RX6 HP
2.5 60 75
3.0 100 120
3.5 130 160
4.0 180 180

i have a hks wastegate and profec b

I dont think anything is damaged it has like 5k miles on it
and did it from new this way.

hmm thanks books for that. Thats awesome it makes me think that my turbo is doing fine. I never thought that anything was wrong really its just that a few people have brought up the fact that im choking the motor and I should have full boost very early with my setup.

keep more opinions coming. Would low compression on the motor move the full boost 1k rpms later??

My low compression motor makes 1 bar around 3200 RPM. 60-1 hifi P trim 0.84 divided, with catalytic converter.

so would you guys agree that 4700 is too late for full boost with a .70 divided housing on stock motor?

the t66 is a big turbo, so your going to have that much lag. once question i have is, when you say full boost how much are we talking?

i wouldn't expect full boost at 3500 rpm with a t66.

What size HKS wastegate?
What if you turn off the PRofec B?


-Ted

guys look at the dyno graph it was 4700 and it didnt matter what boost I ran really it was a all similar. the 4700 was with 16psi in 3d gear. I think it is the standard hks wastegate

You have a turbo with a divided housing but not a manifold with divided housing to match it ? If so, thats not good. Turbonetics even claims that you can damage the turbine if you a setup like that.

i know theres one way that its ok...its either you can you have divided housing without a divided manifold or a divided manifold without a divided housing. One of those is fine im not sure which one. And ted im still fixing problems on the car I got it like this. It was single turbo kinda....all working somehow but a lot of questionable things. I wonder if this is the reason I was getting compressor surge

Either way, if the turbo and manifold do not match you will have exhaust gases jumping all around like crazy resulting in a late spool up.

TTT

so I should just change out the housing to something bigger and not divided? how much is that gonna run me!???