[LM93]

This compressor map has one of the points almost on the 80% island, would it be noticeably different from 475 turbo? I've read that diesel turbos are designed for a narrower rpm range than gasoline ones. Is this true, generally? I don't doubt that diesel turbos work great with an auto trans on the drag strip, but for a mainly street driven car that would be on a road course on public track days, rowing through gears, is a gas-specific turbo a better fit?

Also, how do sub-2500rpm map points factor in? Assuming you shift to not lug the engine, is creeping around a parking lot or driving through a school zone doable if you don't open the throttle to much?

[ponjohn]

Does it really need 12lbs for 548 hp out of 360 cubic inches?

[Tom Vaught]

Originally Posted by LM93

This compressor map has one of the points almost on the 80% island, would it be noticeably different from 475 turbo? I've read that diesel turbos are designed for a narrower rpm range than gasoline ones. Is this true, generally? I don't doubt that diesel turbos work great with an auto trans on the drag strip, but for a mainly street driven car that would be on a road course on public track days, rowing through gears, is a gas-specific turbo a better fit?

Also, how do sub-2500rpm map points factor in? Assuming you shift to not lug the engine, is creeping around a parking lot or driving through a school zone doable if you don't open the throttle to much?

Repost the Turbo Map showing the Lbs/Minute numbers at the bottom of the map. Without that info the map posted is worthless to look at.

Tom V.

[LM93]

Here you go.

[70 bird]

I'm not much for the match bot but my experience bot knows that a 1.32 ar s475 will work good on a 351w engine. If you want a lower rpm set-up you may want to go with the 1.10 ar instead it will spool up about 5-600 rpms quicker. The turbo doesn't know if its on a Ford, Chebby or a Pontiac.

[Tom Vaught]

Originally Posted by ponjohn

Does it really need 12lbs for 548 hp out of 360 cubic inches?

41.48 lbs of air mass will make 548 horsepower.
Be it a 360 engine or a 400 Pontiac engine.
If the turbo is supplying 41.48 lbs of air mass it does not care what the engine size is, 360 cid, 400 cid, or 455 cid.


The 475 turbo has the ability to move 63 lbs of air mass at 15 psi, why would you think it would not be able to make
about 100 less hp at 12 psi of boost pressure.

Tom V.

[ponjohn]

Originally Posted by Tom Vaught

41.48 lbs of air mass will make 548 horsepower.
Be it a 360 engine or a 400 Pontiac engine.
If the turbo is supplying 41.48 lbs of air mass it does not care what the engine size is, 360 cid, 400 cid, or 455 cid.


The 475 turbo has the ability to move 63 lbs of air mass at 15 psi, why would you think it would not be able to make
about 100 less hp at 12 psi of boost pressure.

Tom V.

My gut reaction was that it would take less than 12 lbs to make 1.52 hp / CI.

[Tom Vaught]

Originally Posted by Tom Vaught

41.48 lbs of air mass will make 548 horsepower.
Be it a 360 engine or a 400 Pontiac engine.
If the turbo is supplying 41.48 lbs of air mass it does not care what the engine size is, 360 cid, 400 cid, or 455 cid.


The 475 turbo has the ability to move 63 lbs of air mass at 15 psi, why would you think it would not be able to make
about 100 less hp at 12 psi of boost pressure.

Tom V.

I had a typo above. If you look at that map, it can move .48 Kilograms of air mass per second. I was not paying attention to the specific graph posted and assumed the number on the bottom of the page was in Lbs/minute of air mass flow.

.48 KG/sec = 63.49 lbs /min 1 lb/min will make 10 hp all day long so 630 horsepower at 15 psi of boost pressure.

I ask the OP to repost the Turbo Map showing the Lbs/Minute numbers at the bottom of the map. Without that info the map posted is worthless to look at. He posted a KG/sec map which works when I made the mass flow conversions.

Tom V.

[Noahg558]

Originally Posted by turbo69bird

Use an s475 works just fine. I’ve done it myself w a dead stock 350 ran 11 flat at 10 psi. Worked great on the street. 70 350 2bbl motor out of a lemans. Raced it for a full season that way. Ran good yanked it out and put it in a 67 bird n/a ran well for another 6 years before I lost track of the car.

I have a 71 Lemans sport 350 bored .030 over with stock #94 heads and I am trying to make more power (most likely a turbo) any pointers?