Hey i just recently got done with my 4 inch to dual 3 inch exhaust and now i have a little boost creap issue. My wastegate opens up at 7 psi, i can hold that all the way to about 6k rpms or a little after. Once i hit about 7.5 rpms i hit my boost cut of 20 psi. I have a t04r with a .96 a/r p-trim (Now im wishing that i had gotten a q-trim lol.) on a hks cast manifold and standard wastegate. My wastegate is 40mm, now i know i need to reduce the flow through the turbo. Which means less overall flow(put the silencers in the mufflers?) or more through the wastegate.

Is the racing wastegate the only other one that hks sells that will bolt on? I want to use there gt wastegate since its 60 mm but it uses v-band. Does the gt wastegate come with the v-band stuff needed? Also is there an adapter plate to adapt v-band to my manifold or wil i have to weld one up myslef?

Do you think that 60mm will be enough or am i gonna have to change manifold or housing or what?

 

Same problem I had. Have a 7.25psi spring in the gate and by the time it would hit 6300 it would start to creep and by 7500 it woudl be at 17psi. What timing are you running from 10-20 psi? Is the engine ported at all?

 

Its got a large street port on it. I am running 5-7degrees in the upper rpms/boost.

 

The GT wastegate comes with a V banded dump tube, and a wedable V Band adapter. They are the ****, I will be running one on my supra. The GT, and the GTII arepretty much all the big HP Supra guys use. Carl

 

Thanx for input. here are my timing maps. Who has the best price on them? So far i have found that rx7store.net has the best price.

 

5-7 deg advance sounds pretty retarded to me. Maybe most of your fuel is being ignited out the exhaust spinning that turbine?

 

Crusader9x, I had a very familiar experience. I was using an Hks cast mani, T04s (.96 ptrim), and standard wastegate. I would see boost creep at about 6k as well. I finally went with the hks racing wastegate (50mm version) it will bolt right up. After removing my gate standard I found actual outlet size to be 34-36mm (can't remember). The racing version is pricey but 50mm the whole way. It's a nice piece.

Link

http://www.rx7store.net/index.asp?Pa...ROD&ProdID=630

 

Thanxs for the advice im thinking of going to the gt or gt II which is 60mm.

Well if its safe for me to advance the timing then i will, but how far? I was just shooting for something safe there.

 

That's a good question, "how far is safe?" That I don't know but when I ran 9 deg at 15psi it would creep and when I went to 13 deg at 15 psi it went away almost entirely but I have a stock port. Judge ito was saying that 15 deg (with 10 deg split IIRC) was ok at 15psi. I'm going to try it out when I get a EGT and when spring comes.

 

Is there a wide-band somewhere?
Or are you guys guessing if you're running too rich or not?


-Ted

 

I got a wideband. I keep around 10.5 to 1 or so under boost.

 

I've never heard of the Boost Creap, is he a new action figure? badoompoomp. Seriously,
I have the same issue, was sold a 40mm hks that is in reality a 35mm unit. Putting on
a greddy 50mm on either an hks ss or greddy manifold. The Greddy 50mm measures 49mmbut should do the trick. I'm trying to get info on which is better for 1/4mile, hks or
greddy manifold. I suspect it's a toss up and either will do fine.

 

I always have my wideband in the car also Ted.

 

Pulled the spark plugs?
What color are the spark plugs?


-Ted

 

I have the same turbo, same specs with an HKS standard 40MM wastegate and have no creep issues whatsoever. I do not have any exhaust system restictions either....no cats. Boost is steady at 15 PSI all the way to 160MPH when those pesky commuters get in the way.

 

Mine was steady before i went to the 4 inch exhaust. So i think im just gonna get the 60mm gt wastegate and hopefully that will control it.