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Discussion Starter #1 (Edited)
I've been looking for a turbo to run on my 2900 that is going in my lakester and also for a 2900 if I put one into my '48 GMC. They would of course be different as the engines would be built differently and the needs are different.

Anyway I've looked at a number of turbos, but of course not all of the ones out there that might work. I've plotted their compressor maps with data from Borg Warner's MatchBot program for a lower elevation and also the density altitudes we see on the salt in a couple cases.

Here is an example of one...



I have a number of other plots on the page and also other info such as this...

The Turbonetics 62-1 above is also a very interesting turbo as it looks very nice down low at 8 lbs. of boost and has the potential possibly of over 500 HP. It is offered with turbines in the .58 to 1.30 A/R size so picking one with the A/R to best suit your needs is a good possibility. The 10998 at Summit has a .68 A/R and the 10996 has a .81 A/R for instance. You can find the turbo for less than $800 in the plain journal models and around $1200 if you feel you need one with ceramic bearings. Turbonetics has a lot of options with these turbos and other ones in their line. The 62-1 turbo at 500+ HP is moving into the next category -- Strip/Strip, but this next one for sure is with close to 600 HP potential.
...for the different turbos.

Here is a link to the page...

Atlas 2900 Turbo Compressor Maps I

I've also done the same for 4200's....

Atlas 4200 Turbo Compressor Maps I

There is also info there that will hopefully help someone in picking a turbo for their motor such as look at HP goals not boost goals and how the same 400-500 HP turbo isn't necessarily a good match for any engine wanting 400-500 HP.

If you have a turbo on your motor now and would like me to run the numbers for it I'd be glad to if there is a compressor map available for it. I could add the results to the 2800/2900 or 3500-3700 page if you wanted the info made public or keep it private and just get the results back to you.

I'm also working on a page for the 3500-3700 engines and will post the link to it soon,

Sumner
 

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Discussion Starter #4 (Edited)
Do you think your efficiency numbers are accurate?
Good question. I think they are close enough to come up with a pretty good match. I'm assuming you are talking about the VE. They are in line with what Borg Warner recommends and we know these motors flow very well with their heads putting our better than 1 HP/CI in stock form. Using those numbers also errors on the safe side of making sure the compressor is capable.

I am looking for feedback and Jake on here (LLV.MA5) gave me some excellent feed back...

I made a handful of passes at the strip today and datalogged all of them. I was running 11psi boost and ran a best of [email protected] There was a strong headwind, so I think [email protected]+ should be achievable.

If you run the numbers using my mph and weight (3600lbs w/ driver), and fudge a few hp for wind, I'm right at 300whp. That should be 350hp or so at the engine, which is right where your calculations say I should be at 11psi.

My logs show my airflow maxing at 42lbs/min at 6250rpm (also right where your graph says I should be). Also, my max intake temp was 112 degrees F (after the intercooler and before the meth). Ambient temperature was 58 degrees F. Curious to see what my intercooler efficiency looks like. I think my intercooler is on the small side. I'm still tempted to go water-to-air.
Here is the map I did for his turbo and it is on that web page...



... and as you can see it was pretty close to what his data showed.

I'm not trying to claim the maps are 100% accurate as that is going to be pretty much impossible given all the variables such as altitude, temp, intercooler efficiency and so forth, but I think they are a much better approach than say 'go buy a such and such mm turbo' or 'Joe Blow made 500 HP with XX Turbo'. I'm trying to get people to use the calculator for their situation which hopefully will get them a better match to begin with.

I used MatchBot to pick a turbo for Gary Hart's 4200 (a link to his build was put on here recently) and then talked to Turbonetics about my choice. He liked the choice for the engine but suggested moving to the Hurricane Series with the same compressor. It flows slightly less but since Gary wasn't looking for big HP he said that it would be a more responsive.

As I mentioned in the other post I'd like to get more people to come forward with which turbo they bought for which motor (4 cyl, 5 or 6 cylinder) and see how close MatchBot is to what they have experienced. It would help us all. I'll do that when I get the 2900 running with the turbo/turbos I use on it. Almost any turbo will work to some degree on any motor but why not start with one that is a good match to begin with and the only way that is going to happen is if we share info. We are a very small community vs. the 'other' guys out there. I appreciate all that you have shared on here. It has helped me,

Sumner
 

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This is great information.

The one thing I might change is the boost vs RPM. It looks like you have 0, 4, 8, 10, 10, 10psi for RPMs 2000, 3000, 4000, 5000, 5800, 6300, respectively. But on my setup, the boost would look like this: 5, 10, 10, 10, 10, 10psi for the same RPM points.

I would guess that any compressor under 60mm could make at least 10psi at 3000RPM with a properly sized turbine on a 2.9. This might get interesting as the graph approaches the surge line for the larger compressor wheels.

There's a reason why ported shrounds are increasingly popular these days. With todays wheel geometry, turbos are making boost sooner and sooner. Most properly sized combos are kissing the surge line at lower RPMs.
 

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Discussion Starter #6
This is great information.

The one thing I might change is the boost vs RPM. It looks like you have 0, 4, 8, 10, 10, 10psi for RPMs 2000, 3000, 4000, 5000, 5800, 6300, respectively. But on my setup, the boost would look like this: 5, 10, 10, 10, 10, 10psi for the same RPM points.

I would guess that any compressor under 60mm could make at least 10psi at 3000RPM with a properly sized turbine on a 2.9. This might get interesting as the graph approaches the surge line for the larger compressor wheels.

There's a reason why ported shrouds are increasingly popular these days. With todays wheel geometry, turbos are making boost sooner and sooner. Most properly sized combos are kissing the surge line at lower RPMs.


OK, your boost/rpm points on the bottom in black. Note we are now at 337 HP but there is a lot of wiggle room in that number. At the strip where you figured about 350 at the crank what rpm where you at the quarter?

I also moved the boost up to 16 lbs. (red points) to get you higher in the map where it is making more air. This could be done easily with a 2 stage boost controller (even a home-made one). Up at 16 lbs. you might run out of air before 6300 but even at 5800 you are breaking 400 HP and if that rpm would work at the strip gear wise you might not need the 6300 and as you've pointed out before you can get off the map to the right.

I agree on the ported shroud comment, one can run a larger compressor that might of gotten them into surge problems without the ported shroud.

So did you go run today? Tomorrow?

Sumner
 

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Running again tomorrow.

Last time I was running 11 psi at the strip. I was shooting for 10psi but I have just been shimming my wastegate spring, so it's not exact. It also varies with the temperature for some reason. It runs a pound or two more when it's cold outside.

I'll let you know how it goes tomorrow. My MAF only reads to 43lb/min with my current housing (2.875" ID), so I think 12psi is about my max.

I really am not looking to break anything at the moment. I just want to run 13s at 100+ just to say I did.

If I ever build the bottom end though, I'll definitely shoot for 15+ psi and a different MAF housing.
 

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Dude u have me really wanting to some boost on my 2.8
Enough interest maybe we can get somebody here to start building manifolds...
 

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Mine has taken a few low 20s pulls llv. Push it lol
I'll just turn it up until my rods turn into "S"s, reducing my compression ratio. Then I can turn it up some more!
 

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Enough interest maybe we can get somebody here to start building manifolds...
Yeah thats my problem, not any custom local shops that can make me one. And no one on the forum wants to make me one. They keep the good stuff to themselves. I may have start practicing on makeing my own
 

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Running again tomorrow.

Last time I was running 11 psi at the strip. I was shooting for 10psi but I have just been shimming my wastegate spring, so it's not exact. It also varies with the temperature for some reason. It runs a pound or two more when it's cold outside.

I'll let you know how it goes tomorrow. My MAF only reads to 43lb/min with my current housing (2.875" ID), so I think 12psi is about my max.

I really am not looking to break anything at the moment. I just want to run 13s at 100+ just to say I did.

If I ever build the bottom end though, I'll definitely shoot for 15+ psi and a different MAF housing.
Phew, I was starting to sweat there.
 
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