So after a bit of work (ended up making a cutter and flycutting the pistons for the exhaust valves) I got the new head on, all good! Played with another cam I had for ages which was a 76degree works but it was wayyyyy too big for the street. The old cam was indeed a 68degree works, not that I could confirm it because the figures on the Tighe website are not what one will find at the valve when assembled on an engine so it can be difficult doing comparisons.

Based upon this I had a new cam ground with modified lobe centres and I couldn't be more satisfied with the power delivery and the behaviour of the engine - smoother and better behaved down low and a lovely spread of torque and much improved over 5000rpm - just what I wanted. Reminds me of a 4 valve engine actually. Makes for a lovely street engine that is a pleasure to drive considering there are gobs more power available than one can actually use on the street. Having driven stock L20b's, driving this one is actually a little surreal

The new head/cam has required a bit of a re-tune, might start running out of injector soon, will try again to actually get some data logs, though as mentioned this is difficult on the street. With any luck I'll head back to the track next month with some little drag radials and see what happens

Great read! I like these kinds of builds.

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any chance of a sound file? great stuff to listen to these achievements

I don't have any sound files but I can post a vid or two on youtube at some stage

Found some cheapish SSW wheels in the perfect size and offset months ago and finally got some 225/50-15 Hoosier DOT drag radials. They fill the guards perfectly. This should be plenty of tyre as I don't really want to harm the clutch any more than I have to (still an organic friction plate). Spending 1K on a pair of wheels and tyres for a couple passes down the strip is crazy in my mind, but after 15 years of playing around I figure I'll give the car its best chance of showing its performance (or breaking something

Here's what the 76 works cam sounded like. When I get the chance I'll take an exact vid of the new cam for comparison.

https://www.youtube.com/watch?v=Yri53obm2qI

Also raised the base fuel pressure another 5psi up to 65psi to hopefully squeeze some more injector out of it, has required some retuning.

Be very interesting to see what it does with grip!

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Tyres look phat!

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1972 Datsun 1600, S14 SR20DET Engineered (204rwkW @ 17psi.)
viewtopic.php?t=6579
#SR20Datsun @SR20Datsun

Had a good time trying out the new head and tyres at Willowbank this week, went 11.70@123 then 11.50@124 on 1.8 60' with a pedal, then lunched the front uni which was not really surprising

It was running 2 degrees retarded from last time and still picked up 0.6 second and 1 mph so there seems to be a useful hp increase from the head.

Will check out the box but probably will replace with a RB20det box just cause the current box was a noisy thing. Also might look at the clutch/flywheel while I'm there. I'm lucky I can borrow a car off my dad!

11.50 video https://www.youtube.com/watch?v=yj-bfHWrm4w

and other incar vids etc are on my youtube channel for those interested

It was amazing to finally experience what the car could do after soooo many years

Cheers.

https://www.youtube.com/channel/UCFCVvI ... VHueudPVZA

So there is a fair bit to update here especially for those not on Facebook.

After breaking the front uni a necessary evil was having a new tailshaft made with bigger yokes and unis (Hardy Spicer 21R I think). The old tailshaft (which was actually a 3" 1 piece shaft I found at the wreckers in an R31!) weighed 6.5kg and the new one 10kg. While I was under the car I pulled the box and the clutch, and also figured while I have the money I'd finally get a steel flywheel so forked out for a very nice NPC one which has the capacity to take a 250mm clutch if needed. The old clutch had some wear but was only 2 years old so that went back in. My brother had a RB20det box he wasn't going to use so bought that off him and swapped the bellhousing over. There was really 'nothing wrong' with the FJ box apart from the usual sometimes dodgy synchros and just general noise - the output shaft splines had only the slightest of twist, but the RB box is supposedly better so it went in and only weighed about 1kg more with the L bellhousing.

After seeing the A/F readout from the gopro footage last time it looked like it was going a touch lean up top which I figured was the injectors maxing out (havent been able to data log for years but I know the duty cycle is right up there). I changed the fuel filter (prob 7 years old ) and removed a checkvalve I'd previously installed at the fuel pump because its all I could do to help the apparently marginal fuel system.

Well even though the static fuel pressure hadn't changed it must have been dropping up top because next time at the drags it was quite rich and costing lots of power, it averaged over a full A/F ratio richer and was only running 120mph even though I was taking fuel out. Still, got it to hook up to a 1.59 60' and ran 11.40.

Back home I rethought the fuelling strategy, and also changed the wastegate spring (still had a 10psi spring in it!) to 17psi because it never seemed to want to make over 25psi, figuring the wastegate was simply cracking open. Because I make the exhaust 'leak' at the drags by bolting a spacer in the dump pipe flange, the fuelling and boost parameters are quite different than on the street. Wastegate duty cycle dropped from 42% to 14% for the same boost with the new spring so it made a big difference and expected to have plenty of headroom for boost next time.

Also from seeing how the car would spin the right tyre on launch I put 1 then 2 turns of pre-load in the right upper rear control arm to try to get a straighter launch.

So back at the track last Wednesday, a checkout pass confirmed the fuelling was much closer, still only 25psi boost. But all night I was wasting passes because the geabox wouldn't let me into 3rd in the burnout plus for some reason I managed to change from 2nd to 5th! on 2 passes which I've never ever done before Also was cranking wastegate duty cycle into it and not showing much boost change, only up to 27psi.

For the last pass I cut my losses and just did an angry 2nd gear burnout, concentrated on the launch and gear shifts and it went 1.67 to 60', slipped the clutch a bit through 2nd and ran 11.18@124.2.

We quickly hopped it back around for another pass with hopefully more boost and finally a little more timing in the higher rpm but the lanes were closed After getting home I noticed the front bearing on the turbo is noisier (its 11 years old and has never had water cooling hehe) but it suddenly clicked that maybe the bypass/BOV (which is just a stock plastic EVO9 one given me by a friend) has been leaking above 25psi, especially as the pressure drop across the intercooler rises - explains why its so hard to make higher boost and meaning that going crazy with the wastegate duty cycle would have oversped the turbo and lead to hurting the bearing. The extra hot air recirculating into the compressor (plumback) wouldn't have helped power either I'd thought about getting a decent BOV years ago but a proper 38mm dual port is $400

Video of the 11.18 https://www.youtube.com/watch?v=Gv8247Qp_TI

11.40 incar https://www.youtube.com/watch?v=9a2yskd0u2A

One thing I want to point out in this build is that the basic engine has NEVER been the limitation over all these years - its always the driveline or ancillaries or driver error preventing showing what the engine is capable of at the track.

And at this stage of tune I can see definite benefits in a decent dyno session so that the boost and timing in particular could be optimised, only because it takes many passes down the track to tune all that and I'm lucky to get 4 passes each meeting. Plus the chassis and driveline (clutch especially) are not consistent enough to maximise each pass, but thats kinda what you get on a 'low' budget 'real street' car I guess.

And to me at least, that is what makes this car more impressive and interesting

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green200b - aka Alistair

The fleet:

Australia:
'80 200B GX - the green200b - hibernating
'81 RX-7 - 12A extend port - daily
'74 RX-2 - 13B bridgeport - cruiser

Europe:
'93 200SX - CA18DET - tourer

So after assessing my options I have decided now is a good time to move the old girl on. I have proven to myself that the L20b is capable of running 10's - a clutch, blowoff valve and some more tuning would make it happen but I am not interested in doing that just to run a number that, to me at least, is a foregone conclusion, especially when for the majority of its use (i.e. street) there is really no way of using all that performance. Someone else can take it the rest of the way if they wish.

The car would be very fun and quick around a circuit with some major brake and suspension mods but I just can't see myself actually doing many track days either. I love the car and it has become like a second skin to me, but at the same time life moves on, the car is showing its age, and I don't have the interest in the right areas to properly take the car into its next 20 years.

I am writing up the specs of the car plus sorting all the spares etc and will post a link to a Gumtree ad or something when I put one up.

A genuine cheers and thankyou to everyone who has shown their interest and support over the years! I wish you all the best of times with your Datsuns, especially the hardcore L series ones

someone out ther will get a nice well sorted ride, congratulations

Definitely a worthy achievement. Hopefully someone with the same passion will snap it up...

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1972 Datsun 1600, S14 SR20DET Engineered (204rwkW @ 17psi.)
viewtopic.php?t=6579
#SR20Datsun @SR20Datsun

Well its official, the ad is here

http://www.gumtree.com.au/s-ad/everton- ... 1122523625

Selling all my Datsun gear with it, 16 years is a long time so its time to move on. I'm sure I will miss the car, but someone else can have fun with it now