No. That 43 lb/min is basically the MAX flow that compressor is going to give you. You will find very few people pushing that. It's riding the choke flow, at the least efficienct area of the compressor map and spinning the compressor at near 145000 RPM. That is the mass airflow that you would get if you completely unhooked your wastegate or welded it shut. I don't consider that 'efficient'. Doable, yes, efficient, no.

The 30-32 psi spikes that we are talking about though, aren't at that particular point of the compressor map. These spike would be more at the uppermost edge in the middle, again riding an inefficient area. Some may argue that any area of the map is efficient. Some may not. You can see the efficiency islands right on the map and point your own plots to see the efficiency % that you are running at that boost, RPM, and VE.

The map can tell you that. The thing is that you need to know the VE of your particular setup at a particular RPM and also your IC efficiency. It can all be easily calcuated. Where do you think I came up with the 23 psi or so that a stock turbo will taper to and the 43 lb/min max flow? It's all dictated by the compressor map.


Eric

 

Alright then, bring on the map!

 

OK, here is a copy of the map and I will give you a link to a compressor map calculator that you can use to easily plot points.

Also, I think we sort of strayed away from the point of this...it's not only the efficiency that may not be ideal, but running 30-32 psi at that efficiency on pump gas (93 octane) would just not be feasible without knocking or retarding the timing drastically. Obviously the more you can cool the charge the better off you are. That's why big FMICs help and cooler weather helps, but it won't help to the point that running slightly less boost won't produce the same power on the stock turbo and pump gas.


Anyway, here is the map:


Here is the original thread where I posted that map: https://www.evolutionm.net/forums/sh...d.php?t=285703

(page 2 is where I posted it)

Here is the link to the compressor map calculator:
https://www.evolutionm.net/forums/sh...d.php?t=234959

Post 4 has a link to the whole file as one part.


Eric

 

I like my midrange spike for my road car because it feels good. It is obviously quicker (in the cold weather) peaking to 27 PSI.

I'm within the compressor map, I'm not knocking, it runs good timing, the inlet manifold air temperatures are fine, it hasn't broken yet (and if it does I don't really care).

 

Exactly.

This is how I always tuned with DSMLink.

SQ

 

So run near to peak airflow (power) from midrange to the top end to give you a flexible engine.

If an engine will hold doing this and has all wheel drive traction, then I like this sort of setup, as long as you are over the boost threshold in any gear you very easily get a large proportion of the available performance.

 

Here are the spec's on my car, just to add to this thread.

My most recent log shows the following, in (Almost) 1,000rpm increments:

3.29psi at 2718.7rpm with 9* timing. AFR 13.691. Intake temps 88*
27.5psi at 3562.5rpm with 4* timing. AFR 12.054. Intake temps 84*
26.5psi at 4500.0rpm with 5* timing. AFR 11.848. Intake temps 84*
25.5psi at 5593.7rpm with 6* timing. AFR 11.745. Intake temps 83*
24.2psi at 6468.7rpm with 9* timing. AFR 11.657. Intake temps 81*
23.6psi at 7281.2rpm with 13* timing. AFR 11.578. Intake temps 80*.

Zero counts of knock the entire pull.

Mods only include:

Hallman MBC - My actual spike by JDM MAP was 29psi (For a split second)
AMS LICP, Injen Intake, I/C and Upper Pipes
PTE 680's, Perrin Fuel Rail and FPR
Megan manifold, O2, Downpipe, Cat Delete, and Full 3" Exhaust
Fuzzy Dice on the Mirror.

All tuned by myself, and all done on 93 octane.

I used to have the car tuned for higher boost (Spikes to 29.5psi, but consistently spitting out 28psi during peak torque) but found my car is just as fast with slightly less boost, but a few degrees more in ignition advance. This is what I have found works well on my car by calculating acceleration rates by the log's, and trying high boost/low timing numbers, and lower boost/higher numbers. Funny, but I am directly in between the two. Medium boost, medium timing numbers.

Insight into one more car for reference only.

 

Wow, that is probably the most aggressively tune pump gas evo I have ever heard off. And crazy fast spool up too. I only make 23 or so psi when you are making 27.5

I do run a bit more timing up top, but wow that seems really aggressive.

 

Yeah, I am running it to the point now that if I make a single change to some of my timing numbers, it will immediately jump to about 3-4 counts of knock.

The spool up is helped by the really lean numbers I have at low RPM's. The numbers I posted are samples from the log. I have ported my turbo as well in very particular ways to help in getting it to spool as fast as possible.

I fergot to add that to my mods list.

 

^^^ 27 psi, 12 AFR and 4* ???

Jesus 93 must be race gas compared to our 91

 

What load axis is the car running in at these boost levels?

 

My peak load's are in the high 280's and sometimes middle 290's.

EDIT: I have seen some spikes (Load values) in the 315's, which makes me nervous because of the hotter weather here, as
well as my MAP scalings only going to 300. (Yipes...)

 

I wonder if you map sensor is reading too high. I did some quick, rough math for estimating boost and load and for 27.5psi at 3562.5 RPM, I came up with a load of about 350. (I used STP for CFM to lb/min conversion and I used a VE of 95% at that RPM, so the numbers are just a rough estimate.)

EDIT:Using a more conservative CFM to lb/min conversion of .07, I get a load of about 305. This shows us how important temperature is in mass airflow.

Is anyone else running this kind of boost levels? What load are you seeing?


Eric

 

Apart from a little spike when you first plant the throttle, I find that the boost in kPa and the load are within about 10 of each other in the midrange using a modified airbox, panel filter, but the FQ models do also have a turbo inlet pipe as standard which may or may not rescale things. So in my case 280ish of each.

 

John,

280ish 2-byte load spike for 27 psi? Or 280ish kPa?

I'm curious what your 2-byte load is at your 27 psi boost spike. It will vary a bit with temperature, but I am curious what the 2-byte load value is.


Eric