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l28 turbo with SU/..... Video


chipo280z

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A carb will flow a set amount of fuel for a set amount of air passing through.

 

One SU will be small for a l28 turbo but it will work well up to 4500 rpms (guessing). The hole on the su is about the same size as the turbo so it can't be that far off. However, the fuel bowl might get sucked dry if you don't use a boost sensitive fpr.

 

I have seen one su used on a l24 turbo with good results. However, I don't know the setup details.

 

Why not just use a holley 3310 750? A cheap carb that works nice on a draw through turbo. It just requires a simple modification to the secondary side so the secondarys open on boost.

 

Need to use carbon seals in the turbo for a draw through setup.

 

attached photos of a 1600 cc bug engine with a 3310 holley 750. ran high 11's with almost a stock engine, a big cam, 114 octane, and 14 psi of boost. Both pictures are the same engine but one photo has a custom header. It was just a shop play toy to have some fun at the local dragstrip.

turbo bug_thumb.jpg

turbo vw_thumb.JPG

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Original Crown Conversion worked fine with a Single SU, on 2.4L engines at least.

Biggest issue with the old-tech was no wastegate control. At about 17 psi (and rising) on the Corvair the jet size was small enough even with a retapered needle that detonation dictated water injection (non-intercooled).

 

With a wastegated turbo as is now available, and a retapered needle (or even a reworked jet diameter to flow more fuel, and another accomodating needle) yes it's easily doable for reliable results.

 

But the above statement about the Holley is a good point.

And the availability of a Megasquirt makes both issues kind of a 'Why Bother' moot-pointer, eh?

 

No doubt about it, a Four Barrel on a Bug with a turbo is a menacing beast. My highest boost level with the similar setup was around 25...that's when I found out what 'case savers' were intended to do: Keep the heads attached to the block. Did you guys know you could actually blow a head off a VW?

 

Up to that point, neither did I...

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