Hi all, I'm new to the site from England, I am on Mazdarotaryclub.com in the UK so some of you may know me.

I havent had time to have a good look around the site but there looks like there is loads to view.

I have a UK model TII 1991 FC, it has a street ported 13B engine with series 4 low comp rotors, fuel system, front mount i/c. I have a TD08 Turbo which i think is basically the same as a T88. it is fitted to an SS Autochrome FC manifold with a slightly modified wastegate pipe, which had been englarged to take a 50mm wastegate. The exhaust is 3" all the way through.

As i'm sure you guys know, the TD08 is very laggy but is strong when its on boost. The problem i have is that even with a Greddy Profec B spec II boost controller, the boost starts at 10psi at about 4500rpm and then creeps upto about 13 - 14 psi by the time i get to 7500 rpm. I can hear the wastegate open at 8 - 10 psi but it still increases, the wastegate spring is an 8 psi one

I am looking to get it mapped to about 17 psi with Water inj on 99 rom pump gas but it would be nice to have a more stable boost pattern, do you know why the boost creeps up.

I would be greatfull for any advice

Many thanks
Tony

 

the outside

 

How is the manifold doing?

Got pictures of it

 

its fine, i had an Autochrome manifold on my FD which needed strengthening due to cracking. The one for the FC is much smaller and thicker and is not made from tube, but made in 2 halves. No problems so far and it holds a T88 and running 420 bhp. Its a bit tappy though.

Its not a piccy of the manifold, but you can see where the turbo sits

 

Its a bit tappy though = wht do you mean?

 

Open dump wastage? Got the vac lines ran properly?

 

Sounds like its time for a bigger gate, depending on port design you might be pumping out to much flow for the waste gate to keep up. My friends 50mm waste gate is having trouble keepingboost down on his 60-1. You can try to retarding timing a few more degreese to see if that helps the waste gate keep up. But it sounds like your going to have to go to a 60mm waste gate, or open event your current and see if that helps bring boost levels down.