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Zoom - When I PM'd you (weeks ago) I didn't say my issues were fixed, I told you that we now had a theory why my LAST ENGINE had lost compression on the rear rotor. I also said I had a fresh rebuild and "so far - so good" except for the blow-by - which I thought was excessive.

I know 6's are not good - didn't mean to suggest they were. The only "good" thing about the results of the compression test was the fact that both the rotors were even and all the rotor faces were close. This was a very different result than last time. I also tested the compression BEFORE the engine was completely run-in and BEFORE I had put any serious boost on it.

Also - last time - I lost vaccuum at idle immediately after Steve's tuning session on the car..... I now have exactly the same vacuum after the session as before.... around 15" at idle.

Car feels strong and is running well - I think there is definitely more potential in my set-up. I am going to add some injectors (and some other tweeks) and have it tuned again in the next month or so (hopefully on a cooler day)...

We'll see I guess.... I'm happy with my GT40R kit. I wanted a car capable of 400 rwhp with a responsive turbo. That's what I got.

 

I had this issue with my GT35R. But i dont think itas the turbo.
I think its the new Mazda seals and or the combo of certain port designs and the new seals.
Ive had 3 motors all do this.
Drop compression and start blowing by like a bitch. Also the power levels you guys are making I made with a smaller turbo and stock ports. I think the turbo is capable of much more (GT40R). But the motors are having issues.

 

pm'd you Rusty

 

I also have the gt40r and the car is up and running with some issues. I do not believe any of them to be turbo related. My last turbo was an apex rx6b. This turbo already seems to be a vast improvement. Driveability is great in town and I have not even gone into boost. The car drives very responsive and I can hear the turbo spooling very early. I have to keep my foot out of it just to keep it from going into boost.

however, I too am having some of the same issues as Zkeller and rusty. I am getting what appears to be water/oil in my catch can and underneath my filler cap. It smells fuely. I only have 450 miles on the fresh motor so I am yet to be too concerned. My motor is not making the most even compression on the front rotor. I had it tested right after intall to get a baseline. The results were:

rear rotor 7.1/7.5/7.3 @ 274rpm
front rotor 6.5/7.5/7.5 @ 278 rpm

the sevens are not bad for a fresh motor, but I am keeping an eye on the 6.5. I seem to be getting blow by and think it has to do with a sticky side seal. I plan on changing the oil at 500 and again at 1000 to see if the blow by has lessened.

Once I put around 1500 miles on her I will see how the boost response is. The car feels lighter to accelerate than before. This is most likely due to the larger exhaust housing and reduced back pressure. I took my friend out last night and he thoght I had to have been in boost from how the car felt. The answer was no. She just wants to run. I see no real issue with driveability. It is easier to drive than it was with my twins running parrallel. I think this turbo will easily be a new benchmark once more are in circulation and the numbers start coming in. It also sounds much better than the apex. You can hear it start spooling real early.

Mike

 

the 6.5 # on one face of the rotor is usually caused by a stuck side seal. Generally, it is probably due to boosting the engine when seals are not fully broken-in or by having a very tight tolerance causing the side seal to get stuck pre-maturely. Do you know how tight the tolerances are for the clearancing?

 

I do not know what the tolerances are. This test was done with 50 miles on the engine and 0 boost. The car now has about 650 miles and I have started to add some light boost, 2-3 psi. Vacuum is still low, 11in. I am not sure if the two are related. The drives fine and spools very quickly. I plan on rechecking compression at 1500 miles.

Mike