Max Safe Boost?

[DA BIG ONE]

Wondering what pressures can be run safely on a motor w/19:1 pistons.

I am running the Heath EMC, high pop injectors, B&D IC, high pressure water injection after IC, the turbo is the stock GM-8 blowin 14.5psi after IC @ WOT.

I have read that some here on this board are blowin something like 20+ psi boost, and wonder if these 20+ psi settings are just superheating the charge, or?

Wondering if porting the turbine housing is worthwhile?

[gmctd]

There are two more gages you could install which will help answer your question(s) on turbos and Boost levels.
Excellent digital instruments for pressure and temperature are available for less than 300bucks each, sized around 1" x 2" x 1 - 3" deep.

Digital gives excellent resolution\response from zero to max range.

A 60psi Exhaust Pressure gage, tapped into the exhaust manifolding somewhere pre-turbine - left side, right side, doesn't matter.

Will give you some idea of quick spool-up at low rpm, low exhaust energy flowrates, and increasing restriction at higher rpm, higher energy flowrates.

A 0-150deg Intake Air Temperature gage post- charge-air cooler.
And one, 100-350deg, pre-cooler, if you want to see the real story, there, vs EGT.

Now - by observing Boost, IAT, EGT, and EBP, you can compare actual operating conditions, and results, while varying Boost pressure levels between 10psi and 20psi, under identical loading conditions.

Not that I would suggest steady diets of 20psi into this IDI Diesel, even with 18:1cr.

Exhaust pressure will always be higher than Boost - takes energy to make work, and work to make Boost.

Exhaust pressure in the turbine housing, derived from heated exhaust gas volume, creates velocity thru the turbine wheel, which makes Boost.

More Boost desired, nore energy required, BUT - when exhaust pressure levels climb at faster rate than Boost levels, over-all flow-thru is reduced, such that increasing Boost levels do not further increase power output.

You'll know this when Boost temperature at compressor output unexplainably increases, along with resultant EGT increase, under sustained high Boost requirements, as in towing loaded up long grade(s).

GM-X series turbo should demonstrate this, quite readily, giving you a baseline reference for various turbo upgrades.

Also, spend some time perusing the towing forums, where 18:1 and 21:1 6.5's get a real workout