[DeTomaso] Blow through carb for turbo

[wkooiman at earthlink.net]

There's a very good site that is dedicated to blow through carb turbos.

There are several things to consider.

1.  You need to increase fuel pressure pound-for-pound to compensate, since you will be pressurizing the floats no matter what you do - with blow-through.
2.  You need to worry about collapsing the brass floats, depending on the pressure.  Plastic floats can take more pressure.  I don't know how much.
3.  If you don't use an enclosure, you need to modify the carb, or it will blow fuel out the throttle shaft.  There are several shops that will do the mod - they effectively add o-rings and they port unfueled air to equalize the pressure - so no fueled air escapes.  I'm not sure about the o-rings, but it makes sense.
4.  If you use an enclosure, you don't need to mod the carb.  You can get them from Vortech or Paxton.
5.  You'll have issues with fuel enrichment, since carbs are based on vacuum and not pressure.  I think the carb forum guys simply tune the secondaries very rich w/out power valves.  The thought being that they only hit the turbos when they step on it.  Probably close enough, but not optimal.
6.  If you keep the boost reasonable, you'll have a lot fewer problems.  10psi should be easy enough.  20psi will break plenty of parts before you get it right.

-----Original Message-----
>From: Jerry R Knotts <knottsj at galstar.com>
>Sent: Mar 23, 2011 3:41 PM
>To: detomaso at realbig.com
>Subject: [DeTomaso] Blow through carb for turbo
>
>For the collective.
>
>I have done fuel injection on superchargers and turbos using Fuel Metering 
>Units and Adjustable Regulators.
>
>I am trying to save about $5000.00 by using a carb on my twin turbo 
>Cleveland.
>
>Have a Lance Nist twin turbo set up for a 750cfm suck through that I am 
>changing to a blow through.
>
>The carb for the 355 cu in is a 635cfm to 650, so will a 650 still work for 
>additional pressure from 6 to 10 lbs?
>Do I use an adjustable regulator so my pressure to the carb will go from 7 
>to 17 lbs depending on the boost?
>
>I have blow off valves and exhaust releases controled by the valves.
>
>Will be running twin intercoiolers and maybe methanol injection.
>
>Your thoughts on the carb and fuel pressures needed.
>
>Thanks in advance,
>jerry ( my zip is E-I-E-I-O) knotts
>knottsj at galstar.com
>
> 
>
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