TABrinn Posted April 20, 2007 Share Posted April 20, 2007 I ran across a sight that sells a kit that converts an SU carb to tbi. (www.sidedrafttbi.com) I was wondering if there would be any performance advantage to running these on an old style manifold compared to my current efi intake on my 79 2+2? I plan on using a MS to run which ever. Any thoughts? -Tom Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 22, 2007 Share Posted April 22, 2007 That's a Stromberg, but close enough. Anything that is applicable to the conversion on that site (TR6's) would be applicable to the Z. But the adaptors they make don't fit our domes... There are those who have converted SU's and are running them with Megasquirt. They lurk here. Occasionally I am their unwitting mouthpiece... Quote Link to comment Share on other sites More sharing options...
slownrusty Posted April 22, 2007 Share Posted April 22, 2007 Occasionally I am their unwitting mouthpiece... Oh boy Tony...you're leaving yourself wide open bro! LOL! Yasin Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted April 24, 2007 Share Posted April 24, 2007 i would guess more cfm than standard efi intake.would be a very interesting way of curing driveability problems on old 240. Quote Link to comment Share on other sites More sharing options...
TABrinn Posted April 24, 2007 Author Share Posted April 24, 2007 i would guess more cfm than standard efi intake.would be a very interesting way of curing driveability problems on old 240. I was hoping for more cfm but how much more do you think? Would the gain justify the work involved? Simply put, does anyone know the cfm of the twin SU's and the cfm of the EFI ? -Tom Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 26, 2007 Share Posted April 26, 2007 The CFM is a misleading number as far a capabilities go... The CFM of a stock 50mm T/B was posted somewhere a while ago---say something like 390 or 420 cfm. Will the runners in the stock EFI setup support that at 6500rpm+? The CFM potential of dual SU's bored straight through at 45mm is almost 2X what the stock T/B is, and with larger runners.... You also run into tip-in response issues, blah blah blah. Just keep in mind that a Cosworth Vega (2300cc's) worked fine from the factory with twin 50mm Throttle Bodies on a plenum-styled manifold, and when hotrodded that same manifold was used well over 10K rpm (hey, Cosworth know how to design a head, and the Iron Duke below it didn't know what hit it!) I'm running about for MSA now in headless chicken mode, so don't have time to search the forums for the exact numbers, but I know it was out there. The comparison was that triple Mikuinis with 34mm or 36mm chokes had a CFM potential of 1400 or 1500 CFM and it was in response to someone insisting a 390 Holley was 'far big enough for anything on a Z-Car'--yet 1500 CFM potential makes more HP, and is still driveable. With EFI, the way CFM is measured (at what depression) is different, and the velocity through the hole is not as critical as a carb due to atomization concerns. Total velocity in the runners is critical, but at some point with EFI, you end up with a Tip-In monster and either need a non-linear linkage or other way of controlling off-idle or off-seated throttle excursions. Quote Link to comment Share on other sites More sharing options...
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