Pulled the plugs today to read them and checked compression on the new motor. Then warmed it up and took it out for some more break-in miles this afternoon. Hit it from about 3000 in first and through second had 9lbs at about 12.6 up to 13 afr on my wide band (kinda scary afr). Shifted into 3rd and it hits 11 lbs. then goes to 10 afr (or less). I had to do it again a few minutes later to make sure I wasn't seeing things. This is with only 10 deg timing at WOT while I finish putting a few more miles on it. Going in to get the boost and tune cranked up in 10 more days. Thing is, the old 5.3 was only seeing about 8 lbs with the same spring. Now the question: is it because its a 6 litre now with ported heads and has more exhaust backpressure with the same turbo?

 

What size spring (lbs) are you using? And what size mm is the wastegate?

 

Wastegate is over worked.

 

Yea thats what I was thinkin. Bigger cubes, more heads. Flowing more exhaust to where the wastegate is too small and is over riding the wastegate spring. I may be wrong.... Still learnin this FI turbo stuff . Someone else might need to chime in.....

 

8lb spring and a 38mm as I recall. I can check tomorrow.

 

It's pretty common with sts and stock springs or a bigger exhaust pulse.

A good boost controller will snap it right in line.

 

Thats what I love about this place...instant answers. Ok, since I am going to crank it up to 10-12 lbs when I return for my performance tune anyway, do I need to do anything? I will be running 93 and drive it daily. Wasn't really planning on meth either. Am I ok or not?

 

I thought the physical size of the wastegate would have trouble routing enough exhaust around the turbo to keep the boost at a low setting?

 

One thing too look at as far as running meth is what size injectors are you running? Some people say meth injection is just a band-aid fix for not having enough injectors. If you are not having problems with high iat's or detonation (KR) then not running meth really should not be a problem. Bein that you are down in TX I would suguest it just cause of the heat down there. Also nice thing with running meth is that you can add more timing. I recently got meth injection on my truck that is running 11psi and I notice a tremendous difference. I am still learning about all this stuff. But I would suguest sometime in the near future getting a meth injection setup.

 

Methanol injection is a great thing. It does all that is advertised and can even buy headroom in your fuel system. I still feel nervous relying on it (as I do anything that is not stock). Once you have tried/tuned for it you won't want to go back.

I think you can manage 10-12 psi without the methanol by limiting timing. By limiting timing you are limiting power and you may make similar numbers at 8 psi with 18* as you would at 12 psi with 10*. There is an octane threshold that will ultimately limit your power.