What next should happen

[mtwollet]

Question I have a t-28 That when I just recently got a wideband I've been working on getting tuned to 11.5-7 ish. Right now im at 17psi on 93 octane with a stock SMIC. I know this may seem weird. But on my boost controller the knob is just about turned all the way to its fullest. I read on machV website that efficent turbo psi levels for the t-28 range from 14-18 psi. Should I just be more concered with getting fuel set at or near 11.8 range for better ignition timing , and not worry about running loads of boost,
Keep in mind this is a daily driver that would like to see better HP numbers than 220, from my last dyno. Turbo will spool up to 17psi and hold boost steady without making boost spike like it did in the past, (ex 18-19ish psi then settle back to 17psi).

PS Mods are in my profile if you need to see.

Also my last dyno to get 220 hp was 15psi with a/f at 10.1

Now Im 17psi with trying to get a/f at 11.7ish

Think I should see a improvement. aka is it worth going back to dyno. 75.00 a pop

 

[andymoraitis]

There's a recent thread that has some helpful tuning info that may give you insight as to the correct way to go. The majority of it covers my experiences on a Big 16G and the effect of different A/F and timing numbers on pump gas and pump/race gas mixes. You can find it here:

http://www.dsmtuners.com/forums/showthread.php?p=1658205#post1658205

In general, pump gas will limit you as to how far you can go with boost and timing since it can't deal with knock like higher octane fuel or water injection can. However, if you want to make the most power, keep timing in a steady range (19-20 degrees advance), A/F around 11.5:1 and run as much boost as you can with that A/F and timing until you encounter 3 counts of knock in the top of third. Once you find that sweet spot, that's your tuning window.

Also, with respect to efficiencies on a turbo, these are somewhat more flexible than what you might think. Although the efficiency range is 14-18 psi, you would likely see gains by moving to 19-20 psi provided you don't run into enough knock to pull timing. The limiting factor, for you, is that you're running a fairly small turbo that will generate plenty of heat as the boost is raised. Also, your sidemount is marginal when it comes to being able to cool the intake charge on higher boost levels.

Again, it's finding that sweet spot and I would certainly advise going back to the dyno to try a number of different combinations and see which works best for you.

Drop me a line if you need more info, or if you have questions.

Andy