CFM and turbos
 

A friend of mine an I was talking today and he asked me what cfm my turbo was rated for. I was at a loss, I dont have a clue. For now I have a factory turbo on the truck. I would like to restart this conversation with him and seem at least a little knowledgeable next time. I have a van turbo Im waiting to put on my truck because lack of funds for the flange and new up-pipes, and my wife and I are buying our first house. 3 Questions
1. What cfm is the factory turbo rated for?
2. Waht is a van turbo rated for?
3. What is the 38r rated for?
Thanks

Good question. Like that answer also.

I do not know CFM, but I know how to read the compressor maps.

http://i22.photobucket.com/albums/b3...ressormaps.jpg

This is a good indicator of how both the GTP38(red) and GTP38R(blue) perform. I ran into the choice of rebuilding mine or replacing it with the 38R.

Looking at the comparison chart submitted by garrett, the stock turbo boosts a tad bit quicker than the Ball bearing(BB) replacement.(as you can see the boost climb on the lower left corner) It also holds a better surge line.
(the left side/slope) However, it can only peak 34 psi. Where the BB peaks at 43 psi, and holds out at the upper rpms. (Note you never want to run at those peaks or run beyond the right of line otherwise you will be stalling the turbo.) The wicked wheel upgrade widens the gap between the BB variant and spool is also quicker. However there isn't a compressor map available, but there is plenty of information online that supports that the wicked wheel does spool quicker and surges less. Which is an indicator that the red line/slope would shift more left.

Additionally, you can rebuild the journal bearing turbo for $50 by yourself. Where the BB turbo is garbage and full turbo replacement is needed.

Since I do not use the higher RPMS or wish to crank the boost up high and I like the idea of rebuilding my turbo for cheap. I decided to stay with my GTP38. Click me to see my rebuild result

Actually Garrett offers a CHRA exchange service. Garrett Ball Bearing Service Probably isn't cheap but less then a whole new turbo.

CHRA: Center Housing Rotating Assembly

Yes, you are correct. :-drink

But in the long term perspective I cannot trust the CHRA service, especially if the 38r goes out of production or that that center cartage replacement gets more pricey as it ages. So in the end the turbo is junked. ;)

To get a rough estimate of the cfm of a turbo from the compressor map, take the lbs/min and divide by .07. That is a fairly accurate measure to some extent and is used by alot of people. From every thing I have read before on a 38r, it flows right around 1050 cfm.

So if the stock turbo peaks out at 58 lbs/min, that is roughly 828 cfm.
38R looks to peak at 74 lbs/min, so around 1057 cfm.

Thanks Ziggy, what about the van turbo?

Van turbo and stock use the same compressor, and therefore the same cfm. The van turbo has a larger exh wheel and is able to drive the turbo better and more effeciently than the stock turbo.

That is why you can get more with a van turbo, because it is taking less heat energy (drive pressure) to spin the turbo. So more of the engine's energy can be used to make power to the wheels vs power to drive the compressor.

i thought the van turbo had a bigger exhaust wheel only

Is that not what I said Jam? or did I mess up my wording somewhere?

Awesome, I bought the van turbo knowing that it was better but never really looked into why lol. Thanks for the info guys I appreciate it. In all reality what kind of difference should the van trbo make when I install it? Im waiting to put it on because Im gonna buy bellowed up-pipes and install them at the same time, my up-pipes are leaking and Im only able to make 18lbs of boost

i was trying to go this route and the CHRA cost more than a whole new 38r per clay......

ur right cory i read what u wrote wrong

briefly, what does the ATS ported shroud compressor housing with larger intake opening do for the stock Garrett. I know it is supposed to eliminate surge. And with a larger intake, I guess it flows more? moves the line to the right? what about spool up?

Good question Im also curious about this

there is much info on this forum about the shrouded ATS, but it gets very confusing. Ziggy has a nack for putting it in words I can understand. What say you Ziggy?

I believe ATS worked with garrett to develop the GTP38r, and released their ATS housing right before the GTP38r came out. So I would not be surprised that the blue graph above has some similarities such as offsetting upward and more line on the right. I can not find anything relevant information about the housing, such as if they increased the AR of the compressor housing, which means more flow, less surge, but less spool.

I have never had one, but from my understanding this is what I get from it:

The housing itself is pretty much the same, other than a 4'' opening, and surge ports machince into the housing.

You have 2 options when you have surge, either a WW or ported housing. The WW flows slightly less air to not "out run" the housing in other words.
The ATS ported housing fixes the problem on the housing side instead of the wheel. Thust allowing you to keep a compressor wheel that flows a little more than the WW. It also helps out flow on the intake side going into the turbo.

A turbo with the ATS housing doesn't really flow anymore air than a stocker. Other than when the stock turbo is not flowing much air bc its surging. In other words, it flows the same cfm, same spoolup, same max boost as a stock turbo, just without the turbo.

If that makes any sense

You can also change the turbine housing, bigger AR help with surge as well. It also helps with power at upper rpms and lower's EGT's. All at the cost of slower spool-up.

From what I hear is that the van's turbo has the same compressor side, but a 1.15 AR turbine wheel.

Bigger exhaust housing does work
I rebuilt a Turbo for Mike. With a 1.0 housing and he said it def helped

This question got passed up on the last page

The van Turbo will be a touch laggier on the bottom end but pull harder and longer up top

Any idea what jump in HP and TQ might be there?

30-50 HP / 60-100 tq depending on supporting mods and hpop health

All the mods that are done to my truck are in my sig., supporting enough? Ive only got 101K and my HPOP has no issues., is there anything else I can spend some money on lol

Have you ran ur truck on AE to verify hpop pressure vs duty cycle in all of ur tunes?

That I have not done, I dont have access to that

Where are u located? I'm sure someone on here would help. Data log ur truck with thiers if they are near u

Monroe, Michigan. South of Detroit but just north of Toledo Ohio

I would talk to Joey about a modded 17* hpop if you are looking to put money towards something, unless you are planning on going with bigger inj and turbo later on down the road

my vote is for a modded 17* pump too

Cory arnt you supposed to be at work, lol. I do plan on injectors but thats quite aways down the road. Would the van turbo support bigger injectors or will I have to step up again? Im only looking to make between 400-450HP, nothing crazy... :-innocent :-roll... for now

van turbo should be ok with stage 1 maybe stage 2 injectors
not that i listen because ill be running hybrids with mine

I know that when I do step I want to go with single shots but thats where my knowledge ended untill everyone answered my questions. Im still trying to figure out what would be best for my set up

I've been at it for 14 hrs today working on my suspension, well probably only about 8 of that once you take away an hr on the phone with Jim, and an hr of shoveling a pickup load of corn and lunch and a liquor break. Pictures will be up in a min.


As Jim said, the van turbo will be good for 400-425 hp. But thats getting close with it, IMO

I think I could live with 400hp.... For now. Thanks fellas I appreciate all the help

ps clay can aslo help u with a Termmy modded 17*
Riffraff Diesel: Terminator Modded 17º HPOP

Awesome, thanks. What is the stock HPOP 15*?

Early 99 has 15, late 99 up 17. And there is someone on here with 449hp & 1000ft lbs tq., with a van tubro, so yes it will support that. But if you are e99 go with the T500 HPOP it makes a different.I believe he has 238's 80 over sticks to make that.:-bigparty

Chet

John ur truck is a 01 so stock u have a 17* hpop