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TurboPete55

DHLA 45's on 1000cc turbo running problems

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Hi all, I'm a newby here. 

I have a 1000cc mini turbo with a 7 port cylinder head running twin 45 DHLA's off of a Lotus Esprit Turbo. 

I'm having issues with it running too rich on the idle circuit and has hesitation just off of idle.

The carbs are running:

28mm chokes

30 idle jets

7850.8 idle jet holders

35 pump jets

120 main jets

160 air corrector

Turbo emulsion tubes

30mm modulator rings.

Float heights are both 15.5mm from gasket to float. 

It runs great on main jet circuit but on the idle circuit it runs between 10 and 11 on the wideband AFR. 

Anyone got any ideas how to make it run leaner? as I can't get any smaller idle jets than 30's 

would changing the chokes to 30's help? 

20180629_232206.jpg

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Hi Pete,

Welcome! That looks like a very interesting creation and must be a bit of an animal?

I'm more of an injection man myself but twin 45s on 1000ccs seems like a lot of carb even with a turbo. I worry about the the huge range of airflow you need to be able to calibrate for. While I can see that the on-boost air demand would be well within the carbs range (I guess you must be making in the 120 to 150 hours range?), at low rpm, off boost........ That said, those turbo Dellortos represent the pinnacle of side draft technology, with enormous flexibility, so if it can be done, these are the ones to do it.

Quite a few years ago, Josh Bowler of this form used them to great effect on his supercharged 1300 Spitfire. Not alt of information remains on that though.

There are still a couple of guys who know about carbs that appear on here - hopefully one of them will be along to comment.

Nick

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