Datsun 1600 L20B Twin Webers

Danny Castro Snr, the king of L20B horsepower on Unigroup dyno brings his mildly modified L20B for a run up on the dyno. He's normally at it with some of the highest powered L20B combos that he likes to build. We take you behind the scenes in the dyno room at Unigroup Engineering, Sydney Australia

[@darwonboyful]

Great results from such a mild engine. The mixture plot really shows how fuel injection can fill in all those areas where the mixture isn't optimum even though peak power might not be much more

[@nitrogearaustralia3949]

love this video old school tuning

[@ASoWiDweet]

Love the video mate!!

[@unigroupengineering]

Cheers Orlando!...👍

[@nitrogearaustralia3949]

fantastic video i think he needs to do more

[@TURBOTRISTO]

gosh i wish i had a datsun 1600

[@josecortez5213]

Very nice! I would like a 521 truck with this engine. I have a stock d21 at the moment.

[@craigatkinson420]

Is part 2 finished yet? Would love to see the final result. I love how you break it down and explain it!

[@unigroupengineering]

Hi Craig. No part 2 just yet, waiting for Danny to make another appearance. I'll make sure I run the camera when he's in next.

[@markavramovic111]

Power plateau at 6000 rpm is because the stock cam and ports can't flow more air, despite the low restriction induction setup.

[@donwest5387]

I have a built napz 2.4/SSS head on mine. (suzuki electric power steering)

[@bengooch5787]

From a guy who likes to road tune his twin 40s with a wideband. Have you thought about dropping the pump jets one size? They add fuel everywhere, not just on pedal presses. Might take enough out of the rich spot leaving a simple air corrector tune at the top where they have less overall effect. Oviously no good if it effects throttle response at lower rpms. Just an idea to try. Loving the videos btw, keep it up!

[@unigroupengineering]

Hi Ben, great tip on the pump jets. I've found that they mostly affect high rpm on constant throttle...👍

[@bengooch5787]

@@unigroupengineering Interesting. I do a lot of light throttle tuning for better fuel economy and search for midrange torque with ignition mapping. I found AFRs are richer everywhere when you go a size up, even on light cruise. I don't really take the xflow beyond 6.5k, so maybe missed what you've observed. Please share your final jet changes when you do part 2. Theres not much detailed twin weber tuning videos produced these days. At wot, your mains look about right to me, so interested to see what you do to fix.

[@unigroupengineering]

Hi Ben, What do you run for the bypass for the pumps? I'm finding odd that yours is affected everywhere. Back on this Datsun, my next move was going to be to try another set of tubes, then match them with the mains. As it sits, it's not looking easy. Because if I go smaller mains to clean up lower rpm, upper end is going to get too lean in some spots.

[@bengooch5787]

@@unigroupengineering I have a .30 spill valves. The smallest one you can get without blocking it off completely. Don't like doing that cause it uses so much extra fuel. The issue you have is one i only solved with a best compromise. My rich spot is between 3 and 4k at wot. I think its related to progression drilling and cam choice. I managed to get it into the mid 11s, but no better. FYI, it was much worse on smaller chokes. If you can go up a size, it reduces the signal on the mains in this rpm range. Would need the mains revisiting to compensate for the extra cfm at high rpm. I also found emulsions of the same family perform the same at wot. They only make a difference at part throttle acceleration. Good luck finding the answer!

[@unigroupengineering]

@@bengooch5787 I'll post up the final when we are done. I'm expecting a result like yours though, always a little on the rich side in the middle. This happens because of the refracted wave in the inlet tract without a plenum to equalise it. The inlet charge draws from the carbs, on the way in and also on the way out, causing stand off,, so you get a rich mixture. Nice chatting to you on the matter. I will try to follow this up to see how we finish up.

[@610SSS]

Know any one in adelaide with dellorto dhla jets?

[@unigroupengineering]

Apologies, no one that I know of.

[@donwest5387]

They're Datsun 510s

[@Smickster01]

i had a datsun 1600, 1.8l twin 45's and it was da best car dat i owned. shit, why am i talking like this, im educated.