Turbo calculations and compressor maps

[Pillow]

Can someone verify these calculations for me?  I have gone over this a few times and everything matches what it should.  Also I verified from the specs for my 6.5TD motors and it verified there...  But the Air Mass Flow seems WAY too high in the 1.9 especially versus what turbos people seem to be using!..  Unless no one is increasing the turbo size along with the boost/fuel increases?

Engine Size in C.I.   116
Max RPM                   5500
CFM                           369
V.E.                      80%
Corrected CFM           295
Max Boost in PSI      25
Pressure Ratio           2.70
Density Ratio           2.25
CFM Turbocharged   664
Air Mass Flow lbs/min   46

I know a Diesel moves way way more air than a gasser, but with these numbers puts the 1.9 into a medium size turbo which is much more flow than the stock small turbos can comfortably handle.  Unless a lot of folks here are running the stocker to the ragged edge of efficiency = heat?

Or better yet what are the high boost folks using and I can reverse map it?

Thanks! 

[Pillow]

FWIW those numbers in the chart were lined up...  I am not sure why they came out funky when posted.  Sorry.

[lord_verminaard]

Therin lies the problem, these engines need to move a lot of air with a small amount of displacement, which puts the PR really high in respect to the amount of mass airflow, which is low compared to the PR.  You'll find that most turbos really aren't in their "happy zone" when dealing with that.  The stock T3 on a 1.6TD is actually running pretty close to the surge point with factory boost levels.  Partially that is something that a lot of people here have just dealt with.    I'll be running a Mercedes T3, which is a 45 trim, slightly larger than the factory T3.  I'll be running slightly higher than stock boost, around 18-20 psi or so.  Even though it might be laggy, the turbo will be in optimal efficiency range at that boost level from around 3500-on up in the RPM range, so it should still make good power and run fairly cool.

That's all armchair tuning though, we will see what happens when we actually hit the road with it.

Brendan

[Pillow]

Well said.  That is kind of what I thought.

People are hitting surge on the stock turbos.

...  From one HP calculator flowing that much air will get you 380.01HP!!!  Which is doubtful in real life.

From my late night reading of maps it looks like the Holset HX35 might be a good fit and readily available.  Along with others, but basically solid mid size turbos for a small engine! 

Interesting.  I hope to have a decent list of options to post here to get an idea of what some people are running.

Thanks,

[Rabbit on Roids]

I'll be running a Mercedes T3, which is a 40 trim, slightly larger than the factory T3.  I'll be running slightly higher than stock boost, around 18-20 psi or so.  Even though it might be laggy, the turbo will be in optimal efficiency range at that boost level from around 3500-on up in the RPM range, so it should still make good power and run fairly cool.

It has terrible lag on the stock 3.0L engine.  The amount of lag on a 1.6L engine would be horrible especially anywhere above sea level. 

so its gonna work good at 3500 or over?
that sounds as useless as an *** on your elbow.
its gonna have horrible lag.
these engines stop making power at under 5000 rpms, so thats gonna be under 1500 rpms of useable power. think of it, n/a power off the line till about 3000 rpms. 

[zukgod1]

The HX35 or even the 30 is a really good turbo but your never gonna spool it on these little suckers.

Need to look up 53_willys build and see his turbo.. Now that will work..

[smoken u]

after doing the compressor map for mine, the garrett GT37 seemed to be a decent match, dont knwo its hard to say for the optimal size the numbers say go for a larger turbo, but theres not really enough cfm to spool them.

[lord_verminaard]

so its gonna work good at 3500 or over?
that sounds as useless as an *** on your elbow.
its gonna have horrible lag.
these engines stop making power at under 5000 rpms, so thats gonna be under 1500 rpms of useable power. think of it, n/a power off the line till about 3000 rpms. 

Well, I guess I'll find out.  You can't always go by what the book says I suppose.  Here's the calculation that I've run with the Merc T3 on a 1.6:


Notice the 3rd and 4th points, which are 2250 rpm and 3000 rpm.  At 2250 there should be 9.4 lbs and at 3000 almost 18.  That sounds pretty good to me.

These are the numbers for a 1.6 wanting to make 115 hp at around 18 psi max boost, intercooled, at sea level.  I have peak power at 4500 rpm, sound correct?

Brendan

[gldgti]

so its gonna work good at 3500 or over?
that sounds as useless as an *** on your elbow.
its gonna have horrible lag.
these engines stop making power at under 5000 rpms, so thats gonna be under 1500 rpms of useable power. think of it, n/a power off the line till about 3000 rpms. 

Well, I guess I'll find out.  You can't always go by what the book says I suppose.  Here's the calculation that I've run with the Merc T3 on a 1.6:


Notice the 3rd and 4th points, which are 2250 rpm and 3000 rpm.  At 2250 there should be 9.4 lbs and at 3000 almost 18.  That sounds pretty good to me.

These are the numbers for a 1.6 wanting to make 115 hp at around 18 psi max boost, intercooled, at sea level.  I have peak power at 4500 rpm, sound correct?

Brendan

looks ok i guess but that map is titles "45 trim" - i thought the vw version was 36 trim and the merc version 40 trim???

[lord_verminaard]

Yeah, the VW is a 36, and the Merc is a 45.  I had mis-typed it in an earlier post.

Brendan