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Stahl Header Vs. Tii Manifold Response


jgerock

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There have been multiple inquiries on the subject of whether or not adding a header will improve performance of an M10 engine - especially when compared to a ti/tii cast iron manifold.  Certain older Roundel magazines have included comparisons and opinions.   Here is the response from Jere Stahl in the January 1990 Roundel.

 

StahlletterJan1990_zps5d8faef2.jpg

 

Stahlletterpg61Jan90_zpsdf658fa9.jpg

 

Stahlletterpg62Jan90_zps2a250ad0.jpg

Jim Gerock

 

Riviera 69 2002 built 5/30/69 "Oscar"

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Whoo Hooo.... I feel better now....heading out to the garage to re-install!

Earl

74 02Lux

02 M Roadster

72 Volvo 1800ES

74 02Lux

15 M235i

72 Volvo 1800ES

People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf." -- George Orwell

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I think the key to any engine performance modification is balance between the components.  Just bolting on a header to an otherwise stock engine and driving around town will not produce the desired results. 

Jim Gerock

 

Riviera 69 2002 built 5/30/69 "Oscar"

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After reading these articles and trying to comprehend them in their totality. All I can say is I believe my rod angle is about right when I stand about 18 inches back... And aim right for the center!

Have a nice day!

Rey

I'm a BMW Zombie and there's no cure!

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Perhaps I'm just getting old but a well calibrated timing map and an engine in perfect tune seems like the best mod.... ok ok that with balancing and blueprinting during a careful build.

76 '02 owned 20 years.....project for the last 13. I should probably be faster than the rust I'm chasing.

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I think you would be better off with the 1 3/8" header with that little cam and small carbs.  You might loose a few HP at the top end but you will gain a lot in torque in the mid range.  Looks at the torque figures and where it peaks between the 1 3/8 and 1 1/2 headers on the Tii.  The smaller header is a much better compromise for a street car. 

 

Look at the AVERAGE torque through an RPM range:

1 1/2"  header  2000-5000 rpm 115.8 lb/ft average

1 3/8"  header  2000-5000 rpm 124.2 lb/ft average 

1 1/2"  header  2000-6500 rpm 99.15 lb/ft average

1 3/8"  header  2000-6500 rpm 116.2 lb/ft average

 

You need to move a LOT more air to make the larger header pay off. 

1970 1602 (purchased 12/1974)

1974 2002 Turbo

1988 M5

1986 Euro 325iC

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ugh, why is it speed based and not RPM based? haha

 

Also I am curious how they got those AFR's to be so spot on for both runs.... is that still running a k-fish or is it running EFI?

1974 Grey European Market BMW 2002 

1976 Yellow BMW 2002 "GOLDENROD" SOLD

1972 Yellow Austin Mini 1000

A bunch of Bikes...

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