I posted this in the Power FC forum and have t got any response. Jut wanted to get some opinions.

I'm waiting for my new turbo and manifold but currently I'm running a gt35r with .82 hot side on an rx7store manifold with tial 44 wastegate recirculated. The car feels like its being held back. I'm running 20 lbs of boost but at 6 degrees timing with 15 degree split. I have gotten a few knock readings in the 70s in a few cells and that was what led me to lower the total timing so much. I think the timing is too conservative and that combined with the small A/R housing is leading to high EGTs and causing knock. I'm gonna go back to the 15 at 15 at peak torque and only pull 1 degree of timing per pound of boost. And also maybe run 12 degrees split. The motor is stock reman from Mazda.

My new manifold has EGT bungs and I already have a TC-4 with sensors waiting. Do you guys think such conservative timing can lead to knock or just lower power?

 

you can go too far conservatively and run into issues. your figures are a bit overly conservative.

but the next question is, were the high knock readings under heavy loads or under moderate loads while cruising?

on the early engines i generally run 15 degrees at 15psi, add in that is with the timing set at TDC on the 5ATDC mark so the timing is actually 20 degrees at 15psi, pulling 1 degree per PSI with a flat 12 degree split and i consider that conservative.

if you are getting knock only in specific cells then you are either getting noise or have a mapping issue, peak torque at about 5600 is the only spot that is the exception.

 

What type of fuel are you running?

.82 AR turbine at 20 psi = much restriction and high back pressure.

 

I am running pump gas with 500cc of boost juice, which is 49/51 meth water. I actually was logging the last time I popped a motor and the knock reading was in the 70s. The motor before that I wasn't logging but the commander had a peak reading of 146. That was why I was so paranoid.

I know this setup up is very restrictive that's why I'm gonna lower the boost to 15 but I'm gonna add timing and see how it goes. Also, I'm running the NGK 7420s with 10s leading and 11s trailing. I might switch back to 10s all the way around because this may be a factor as well.

I can't wait for my new turbo/manifold combo to arrive!

 

Contact tom94RX-7 as he runs a similar setup.

 

Jimmy,

I've never personally seen knock from too much ignition retard, just sky high EGTs( I saw a turbine housing go clear and could see the turbine spinning inside).

As mentioned the knock can be drivetrain noise too.
Once you get your Adaptronic plugged in, use the head jacks for listening to the knock sensor.

 

it would have to be a bit more drastic and the results would also be a bit more drastic, ie trailings firing on the intake stroke but it takes about 30 degrees of retard.

it's probably just drivtrain noise that the knock sensor is picking up if it is in the mid range cells.

 

The couple of high knock readings I got where around 4800 and 6500 under full throttle. Elliott, I finally got that starting issue sorted out so now I'm gonna install the Adaptronic this weekend. Hopefully, the new hardware will arrive soon after.

Meanwhile, I'm gonna add four degrees of timing and decrease split from 15 to 12. I'm also gonna swap out the spark plugs to 9/10s.

Thanks a lot for the input guys!

 

Wouldn't 15deg advanced from 5deg ATDC be 10deg BTDC?

 

yes, i had a brainfart when i wrote it.

 

Your other stuff should be done this week!

 

I tuned a customer's car I was getting knock readings no matter if I retard the timing or add fuel, I then installed a knock box and free revved the engine, it was drivetrain noise and othe vibration, the customer had solid mounts on the car.