Datsun Roadster Forum-311s.org

We had the opportunity to dyno tune Brian's (Bkippen) '67 2000 earlier this week.
Brian's build thread of #427 is here:
http://www.311s.org/phpBB3/viewtopic.ph ... 7&start=30


After he completed the "gentle" break-in of his Hasselgren-built U20 with a thousands-of-miles roadtrip he wanted to have it tuned. He also wanted to test different Solex filter housings.

The U20 has a C cam, .040 pistons, 44 Mikunis, a lovely JT68 exhaust system and 9:5:1 compression on 91 octane:


On the dyno:


You can hear the Solex-U20 sing in this video below. Keep watching as Brian took videos comparing the open vs late elements...it's ALOT louder with the early style:

[youtube][/youtube]

And, the magic numbers...Brian baselined at 121hp/122tq and left with 142hp/134tq to the wheels:

Very nice power delivery! And a great example of how tuning is critical

Thanks Brian, your roadster is immaculate...and fast!

More pictures here:
http://www.zcarblog.com/2017/12/08/perf ... -2000.html

Thanks for the write up Alvin! A nifty note. Changing from the late comp housing to the early open housing increased the hp by 7. The remaining 14 horsepower was obtained primarily by using the 123ignition and a final icing was a slightly larger main fuel jet.

I can listen to that sound all day! Beautiful car bkippen, and thanks for the write up Alvin.

Oh wow, thanks! Very cool..

Awesome to see a comparison with different air filter housings! Would be interesting to see a similar test done with different length velocity stacks as well... Anyone?

Great post...thanks for sharing! The car looks awesome.
Nice to have empirical numbers.

Dang, I might have to source an early filter housing!

Stunner of a car, great engine result, so fun when the tuning improves things so nicely! Very interesting that the housing makes that much difference. Was he using a different backing plate as well, or just the front cover? The original had built in velocity stacks, and they can make some flow improvements. If it were just the front cover, that is quite significant as well. If so, I wonder how it would respond to additional holes being drilled in it as some have done. It has been my understanding that Nissan was trying to make the intake more quiet, but if it costs power, well that's a no go!
What did you finally come to for an ignition curve? It looks like she might have miss-fired at about 5000 rpms as that torque was doing great then dropped suddenly for a bit, then recovered and even increased. Were you running more or less advance above 5000 vs your original timing? She really spikes up nicely at 5200. I see you had 7 recorded pulls; did you print out the others, noting what changes you were making and the result (I would assume so, as you know the intake was worth 7, timing worth 14 etc). What was changed first, intake or timing (I would assume timing, but of course everything works as a system). 21hp/12tq change, that's freakin great, well worth the dyno time cost!
I'm sure others will be interested in your final jetting too. Assuming 37mm chokes?
Congrats on a GREAT car and build!

bkippen wrote:Thanks for the write up Alvin! A nifty note. Changing from the late comp housing to the early open housing increased the hp by 7. The remaining 14 horsepower was obtained primarily by using the 123ignition and a final icing was a slightly larger main fuel jet.

Thanks for sharing I was wondering were you got the increase from,
And congratulations on a beautiful example of Roadster

Very impressive numbers for a 50 year old 2L. A little better than my stock SR20DE S14 and only 18 hp and 7 lbft of torque less than my SR20DE S15 Autech with 11.7 to 1 compression.

Well done.

Shannon

Quite the the roadster!! Sounds great! Must be fun to take through and around Tilden Park!

Cheers
Matthew

sfdaugherty wrote:Very impressive numbers for a 50 year old 2L. A little better than my stock SR20DE S14 and only 18 hp and 7 lbft of torque less than my SR20DE S15 Autech with 11.7 to 1 compression.

Well done.

Shannon

Shannon,
We dyno tuned our friend's Autech SR20-powered Miata just before JCCS. This was built by Spriso and Eric Straw:




With a few adjustments, it made 179hp/149tq at the wheels, on 91 octane. I thought she was quick when Diamond gave me a ride back in August, but now it must absolutely rip!

[youtube][/youtube]

GeoffM wrote: Nice to have empirical numbers.

PREACH

With a few adjustments, it made 179hp/149tq at the wheels, on 91 octane. I thought she was quick when Diamond gave me a ride back in August, but now it must absolutely rip

Alvin:

Nice to have something to compare.

Mine only put out 160hp and 139tq (also on 91 octane). The main difference is probably that he can run that beautiful factory stainless steel header. Other differences might be the altitude (6000ft) and the dyno. I would think that dynos would compensate for altitude but I’m no expert.

Fun fact: it put out 165hp when the k&n air filter was removed.





Shannon

bakerjf wrote:Dang, I might have to source an early filter housing!

Pretty sure Brian's got my repro early AF assembly with 2" K&N and included velocity stacks too. Also the light steel FW and 225mm clutch yow!

We have another filter element to test too, but thats for another day/another thread. U20, the quintessential roadster engine.

Nice work guys!

I do have the Jim special air box.

The sag Greg mentioned is likely due to timing. We ran several runs and adjusted the curve. If I had an entire day at Z car garage and plumbing for a vacuum signal I’m sure we could steady it and likely increase output by a couple hp.

Here is my timing curve. A note is I am running 17degrees static so the numbers you see are 17deg plus the programmed number.

I am still selling these distributors too.