I5 GT Turbos 2871 / 3071 / 3076 / 3082 / 3582

[EspenW]

i was referring to the actual number if the losses were added to it.Not the procedure from which it was made from.
I just think that a rough calculation that adding 100hp to a whp number we get from any type of dyno for a 4x4 car is completelly wrong.

Absolutely agreed. WHP will vary drastically between dynos.
For example the R35 Nissan GTR:
405whp on Dyno Dynamics RR
410whp on Mustang RR
430whp on Dynojet RR
458whp on Dastek RR
460whp on Dynapack hub dyno

Dynos are tools for measuring before/after gains, not calibrated instruments for measuring absolute values.

[Ross]

The 72 percent efficiency island goes up to 2.6 bar so i would run it up to that pressure at redline, granted it drops down to 65 percent at 3 bar.

Just the same as the efficiency on the 35R map is 72 percent up to 2.2 bar.

As per billman's post, that's not healthy for the turbo. The graph combines 3 factors - efficiency, pressure AND flow in lb/min. You have to take those into effect, 2.6bar at the redline on the I5 will be WAY above the compressor's max flow rate and the turbo will be dead pretty quickly if you overspin it in an attempt to do so. I'd run the GT3071R, calculating from that map, at circa. 1.7bar at the redline.

[gnutz2]

I see what you mean but i said at redline you can run the boost at 2.2.

You would never get 2.2 bar at 3000 rpm.

More like 1 bar at 4000 rpm and it climbs from there and puts the gray dots on the compressor map to the right side of the surge line.

[Billman]

@Gnutz

OK, to show it to you graphically see the gray dots. They show where you oporate your turbo if lets say you run 2 bar all the way from 3000-7500.

[IMG][/IMG]

[A80Avant]

i was referring to the actual number if the losses were added to it.Not the procedure from which it was made from.
I just think that a rough calculation that adding 100hp to a whp number we get from any type of dyno for a 4x4 car is completelly wrong.

[EspenW]

360-370hp at the wheels is not more than 430hp at crank. at least according to the calculations i get through the PB

Totally depends on type of dyno. 370awhp on a MAHA would mean close to 600hp at the flywheel (according to the MAHA dyno).

[gnutz2]

The 72 percent efficiency island goes up to 2.6 bar so i would run it up to that pressure at redline, granted it drops down to 65 percent at 3 bar.

Just the same as the efficiency on the 35R map is 72 percent up to 2.2 bar.

[Billman]

for comparison reasons here is a map of a holset compressor (if my info is correct it is the same as on the small HX40 with 55-56mm Inducer and 82 exducer).

[IMG][/IMG]

[Billman]

I run my 35R up to 2.2 bar at top end.

If i use Paul's Excel correctly then you are with this turbo and 2.2bar at the redline also way out of the efficiency of your turbo. Dont see only the PR -1 bar (atmo) but also the pressurelossen on you piping ect.

[Billman]

Why only run 1.7 bar to redline.

The compressor map shows up to 3 bar at the top end

look

yes but on the 5 cyl turbo you are going to be with 2 bar at the redline way out of the efficiency of the compressor.

[A80Avant]

360-370hp at the wheels is not more than 430hp at crank. at least according to the calculations i get through the PB

[20vQC]

I like that map of the GT35 with that comp housing... you get 79% of efficiency between (approx.) 1.35 to 2.55 bars of pressure. It obviously depends on the air flow required.

[gnutz2]

I run my 35R up to 2.2 bar at top end.

[gnutz2]

That's one of the best 3071r dyno plots I've seen, if your saying you have 368 at the wheels it equates to 450-460 at the crank.

There's more to be had as you can run 1.9 to 2.0 bar max and then run 1.7 to redline

Why only run 1.7 bar to redline.

The compressor map shows up to 3 bar at the top end

look

[EspenW]

Rod failure from compressive load is dependent on peak cylinder pressure. Increasing torque output will increase average cylinder pressure, but not necessarily peak cylinder pressure. It depends on whether the torque is made from flow, boost, timing, longer stroke, etc. Different fuels will also produce different peak pressures. Thus, peak torque is just a rough guideline for risk of failure.
Point of failure from tensile load is a lot easier to pinpoint, especially in a NA engine. In a turbo engine, turbos actually helps protecting the rods from tensile failure at high rpm (by providing an opposing force through gas load and exhaust back pressure).
Installing stronger (and lighter) rods if the engine is apart is a given. Good insurance and allows higher rev limits than stock rods. Note that overrevving rods can take them into plastic deformation, thus radically weakening them, then bend them on the power stroke, or during mild detonation, making it appear that their failed from compressive load only.