davepl

I'm trying to size a blower for a 502cid project, and I can't for the life of me find compressor maps at the Procharger.com site. Do they publish them? Flashy brochures aside, it seems like the most basic info you'd want!

I'm considering the D1SC and the F2 (presuming I can keep accesories with it), and its for a '69 Camaro.

Not sure if the D1SC can flow 14psi into a 502, but without a map, I really have no way of knowing!

Thanks,
Dave

Ponyhntr

Dave-

ATI doesn't make compressor maps. But I can tell you, a D1SC will not make 14 psi on a 502! You will want to go with the tried and true F2!

If you call them to get their recommendation, that's most likely what they will tell you.

engineermike

I think they're hiding something since Vortech publishes theirs.

davepl

Well, I spoke to ATI about it this morning, and to paraphrase, they like to do more empiracle testing at the drag strip rather than on a test stand. He said the company founder isn't an engineer, but a racer, so they let the results speak for themselves.

That's all well and good if you happen to be running the exactly same engine combination, but for those of us that want to simulate the airflow in Desktop Dyno or something similar and then pick a blower that's particularly efficient at that flow, its not much help.

As you can tell from their websites, Vortech and ATI have a huge amount of animosity towards each other, so I don't place a lot of faith in what either has to say about the other's products.

All that said, from what ATI and other members have said, I think I'll be going with the F2 and a 12-rib serpentine setup.

Ponyhntr

To say it again, and to back up Dave's post, ATI doesn't even MAKE maps...even for in-house use, so there isn't anything that CAN be published!

Ponyhntr

From my own experience....I would stay FAR away from a 12-rib setup with an F2! You will have more belt problems than you care to have. Go COG!

davepl

Can you describe the problems you had with the 12-rib? Unless there's some way to retain all accessory dries, I don't want to go cog, as this is a street car.

NoStock

Doe's this problem also pertain to D1-SC aswell

Ponyhntr

The main problem is that the F2 takes a good bit of power to drive it, and the 12 rib belt may have a problem with slippage. What all accessories do you have? ATI's cog crank pulley only has one v-belt groove on the back-side, but I'm sure someone like ASP could make an extra pulley that you could put either behind or in front of the ATI pulley to allow you to run more than one v-belt.

Ponyhntr

Definitely not. The D1SC doesn't take nearly the drive power that an F2 does.

engineermike

That's such a cop-out on ATI's part. It's a ludicrous and absurd claim. They're either a) hiding the compressor maps, or b) didn't do a good job of engineering their products. In either case, it casts serious doubts about the quality of their compressors. In order to judge the effectiveness of different impeller designs, casing volutes, etc. . . you HAVE to do a compressor test. Otherwise, you're leaving alot on the table in terms of performance. If what they're saying is true, they're the only compressor manufacturers in the world that don't test theirs. Also, I absolutely gaurantee there is at least 1 engineer in their staff.

Mike

markinkc69z

Go on with yourself Mike. I really don't understand what the issue is. A centrifugal supercharger is not driven by an electric motor when installed, nor is it enclosed in a test chamber. Airflow testing is done during development and the supercharger is driven by an engine. We publish all of the information needed to select the correct supercharger for the application. Keep in mind that superchargers are most efficient at the top of their rated rpm range. Centrifugals produce boost such that twice the blower rpm will produce 4 times the "boost". Possibly knowing how to use the provided information is the hangup and if there are any trouble areas all one needs to do is give us a call. With the provided information one can deduce what "boost" or airflow the unit provides and how suitable a unit would be for a given application. The numbers are there to factor pressure ratio, which is the upper limit of a superchargers efficiency curve. Compressor maps are occasionally ordered and produced by engineering for internal use, but they are not suitable beyond their internal needs. All marketing aside our superchargers have provided untold thousands of enthusiasts with reliable power that in same cases have set ET and MPH records in motorsports and allowed many to earn points championships in heads up racing. All of these accomplishments have come about due to intelligent engineering, engine building, chassis tuning and dedication on the part of the people involved....and no compressor maps were used or injured in the process.

engineermike

Mark, let me first thank you for taking the time to reply. My comments are as follows:

I understand that you give us most of the information we need to choose the best ATI model that fits our needs. My beef is that we can't directly compare yours to other brands. For instance, if the D-1 at a Rp of 2:1 and flow rate of 80 lb/min is 67% efficient, then the T-trim Vortech at 70% would be a better choice. My T-76 turbo is actually less efficient, at 65%, at the same point. If the D-1 is 76%, then watch your sales increase.

Believe me, I am quite familiar with the affinity laws. . . It would also double the flow rate, but require 8 times the power to drive it.

That makes me feel alot better about the engineering that goes into them. However, if you think that we don't know how to use compressor maps, you're mistaken. Probably 90% of users don't know how to read them, but the other 10% might lean towards a competitor that publishes theirs.

Well, there's the old adage: Are they fast because of the supercharger choise, or in spite of the supercharger choice. Just like many other things, the world may never know.

davepl

Empiracal testing is all well and good, but it doesn't fully substitute for compressor maps.

Personally I would not use them to compare competitors products, because I wouldn't assume the test scenarios are always equivalent.

But let me tell you why I brought this up in the first place: If I run my projected 502 through Desktop Dyno, I can determine exactly what the CFM airflow is, given a desired boost ratio. So how do I select from ATIs blowers one that is at its peak efficiency at this flow rate and pressure?

Given flow maps, you look up the RPM you intend to spin it, the desired boost, and your projected airflow, and you would be able to tell if you should be going with a D1SC, D1R, F1, F2, etc.

Knowing that "Bob's car is fast and a lot of ATI customers have fast cars" doesn't do jack to tell me whether or not the blower I select will be running at 65% or 78% efficiency when I come off the transbrake, does it?

Turn this around: what if you were a cylinder head porting company and didn't release flow numbers, using the exact same logic as in the posts above to defend their absence?

engineermike

That's why there is a standard (SAE J1723, I think). That way they're all on an even playing field.

Also, good point about the cylinder head flow numbers. . .