HIF38 to turbo?
Turbo Mini Forums

hi, i am chris.
i have a question about hif carbs.
i plan on using a hif carb on a 600cc nsu engine with a turbo.
i love the hif44 carbs but i think that is a little bigfor what i want so here my questions:
is it possible to use a hif38 in turboaplication?
will a metro turbo needle fit also the hif38?
can i use the hif44 rebuild kit to convert it of are the partsnot fitting...for sure the garkets to manifold and plenum will not ...

i have to mill a groove in the carb housing right?

hope somebody that had both carbs in hand can help me out.

wishes
chris

You can use any HIF carb, the principle is the same to convert it from NA to forced induction. The main issue is that the Metro plenum won't fit, so you need to sort a way to keep the float bowl pressure above the boost pressure.

To answer some specific questions:

No, the needles are different, the 44 is thicker as the jet is larger.

No, the rebuild kit won't help.

Not sure there is a need to mill the groove.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

thanks for the fast awnser.

no grove needed? what is the big difference between hif44 and hif44turbo...can you help me out here?
i thougt it was a groove with seal somewere in the body. and the pressurized float bowl + different needleand maybe jets. as long as i have seen has the hif 38 the small pipe on the manifold side like a hif44 turbo...so it "just" need connected to the bowl right or am i wrong?

manifold and plenum will all be homemade. the engine bay is different.


cheers chris

The groove allows a rubber seal to be put between the dashpot and body. A bit of metal polish and a bit of spinning the dashpot on the body (like grinding valves) will give a good enough seal.

The fuel pressure in the folat bowl is increased through a hole that is fed from the plenum. The plenum has a restrictor in it, this causes the pressure across the jet to be reduced by 3 psi compared to the float bowl. Thus fuel comes out during boost.

The non-turbo carbs have the hole for this pressure feed blocked up, but as you say you can just use the breather pip. Problem is where to take the feed from. Some have successfuly used a pitot tube, others have taken the feed from before the intercooler where pressure is higher.

All 44s have the same jet size. As do all 38s, but the 38 has a smaller jet. the fuel metering is set by the needle. Here's a great thread on tuning it.

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=159683

Some great info here too

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=217478

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

thanks for the explanation and links! you are my hearo of the day. i will try the pilot tube and in fact i am also using a intercooler i have a sec. option.

thank you very much!
chris

Edited by mymedusa on 4th Feb, 2013.