I run 900 lb springs in the race car. I would have thought you would need a bit softer for a road car.
What spring rate do you ahve in the front and what swaybar?

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Circuit Race 1600 in the build

So I chose wisely then Lampy as you have great lap times at barbagello

I chose 900lb because it's easily available (datsport) and have read it works well with a 230-250lb front spring. I have 250lb front and maddat sway bar (unsure of size)

the 675lb i have are way soft for me after giving some blast to the car and thought 700lb kings (KDRL-07's) not worth the small increase. also with a 7 month old daughter i'm not driving much (baby seats in safer car) so at the moment i'll mostly get out to a few hours on the track every couple months so it's becoming more track and street car (but don't want to overdo the 'trackness' in the car)

we will see. I hope I like them

I run Koni red adjustable shocks in the rear. They seem to work well on the street and can stiffen them up for the track. Have you looked at that option?

no sounds like a good option.

Whats the latest with this thing?

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Ongoing Project: 1972 Datsun 510 S13 SR20Det. http://ozdat.com/forum/viewtopic.php?f=33&t=17898
New Daily: D22 Navara (The new workhorse)
Retired 12/2016: MY98 Subaru Impreza RX
Previous Car: Restored Green 1972 Datsun 510, Hot L18

exhaust mods!

tried the 2.5" center pipe and lost driveability. went to 2" and drove really well around town but when hammering around the track it still didn't feel like more power than the s14 engine as already mentioned, so now I'm re doing the whole exhaust in 2.25 mandrel mild steel. but, I am putting in an exhaust butterfly that works off vacuum. its just a fairly cheap ebay one.
I will put it in the tail section after the diff. this will hopefully a: quieten the car down a little when cruising and around town and then B: (hopefully) increase driveability at low revs by effectively making the exhaust smaller.

I've set it up so under full vacuum it isn't closed fully but instead mimics about a 1.75" exhaust (as in open area around butterfly flap) so also when coming off heavy throttle when the flap is fully open it wont fully close off high rev flow.
I hooked this up to vacuum from the inlet and put it on the dash to see what would happen under various throttle conditions and it does seem to work well. in theory. it gradually opens when accelerating in light to medium loads, fully opening immediately under heavy throttle and not really opening at all under very light throttle. sounds great but the proof is in the pudding. should be finished in a week or 2 as its pretty time consuming groveling under a car doing an exhaust. should be way better than the dogs breakfast press bent crap that was under there, or at least it will look better

also got the 900Lb springs in and cant really tell to much difference around town. I also wound the toe out heaps which helped cornering but wound out to much and it became freakin dangerous when excelerating! so wound it back but that is something to tune at the track next to eliminate this under steer rubbish.

and when the exhaust is done i'll tighten up the rear crossmember with what the US guys call a 'savage washer' instead of poly mounts as I don't have time to take out the CM for bush changes and I want to save the money.

couple other small changes so i'll take photos and report later with the exhaust mod photos and update.

Great update mate. I'm very interested to see how the exhaust modification goes. Please post some pics of mounting this up and where you tapped off the inlet.
The question I have is do you notice any exhaust noise inside the cabin before and after?

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

Baz once told me with a NA SR (I was considering it at one point). To run 2.5" from the standard exhaust manifold (because it flows pretty well apparently) down to about the gearbox x-member or just after, then reduce down to 2.25" for the remainder.

If you're putting the butterfly valve so far down track, how do you think the pressure difference across the length of the car from valve to engine will affect it? Solid tube like brake line would be best in this instance i would think.

Changing x-member bushes is easy once the exhaust is off. Loosen both bolts, then you can drop one side down and fit in the new bush then drop the other side down. and do same I did it with my diff still attached to the x-member.

2mm toe in should be a good starting point. Toe out on the front, toe in on the rear.
Otherwise, i'm glad for the update!

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Ongoing Project: 1972 Datsun 510 S13 SR20Det. http://ozdat.com/forum/viewtopic.php?f=33&t=17898
New Daily: D22 Navara (The new workhorse)
Retired 12/2016: MY98 Subaru Impreza RX
Previous Car: Restored Green 1972 Datsun 510, Hot L18

2.5" is apparently optimal for up to 260hp? or there abouts, 2.25" up to 208hp and 2" 165hp from some Online calculator thing. so I am hoping that this autech engine feels like the s14 I had because of the 2" pipe restricting flow to (coincidentally) the same hp output as the s14engine.

2.25" should unleash the other 35hp... According to Internet science

The ex valve was tested with 3m vac tube T off of the brake vac line It worked well and brakes still worked but probably should not use this for actual setup. Haven't looked at the manifold too intently just yet for vac location. It's all about does the thing work first in situ.

The placement of the valve at the back may not be optimal for trying to increase low rpm drive ability?as most of what I read about the EXUP on bikes has them right after the headers. But not sure how a cheap eBay one will hold up there.

It's really all just suck it up and see stuff.

How's this thing coming along now?

_________________
Ongoing Project: 1972 Datsun 510 S13 SR20Det. http://ozdat.com/forum/viewtopic.php?f=33&t=17898
New Daily: D22 Navara (The new workhorse)
Retired 12/2016: MY98 Subaru Impreza RX
Previous Car: Restored Green 1972 Datsun 510, Hot L18

glad you asked as I was going to be posting some updates soon because...back, seats, back, alright!

more on the back seat later (i haven't had on in there for a long time)

the exhaust thingy (i was reading your exhaust modification RJB510 with excitement then disappointment at the outcome, oh well bigger muffler?) the exhaust thingy didn't really work as i planned. i had it right in front of the rear muffler. maybe not ideal. and i switched the vacuum on and off with an old lego pneumatics switch i had from an 80's set as i drove along.

low response driveability didn't really improve from seat of the pants feel unless i really dialed in a lot of closure on the butterfly but then it would open very quick under only slightly more engine load which wasn't ideal in mimicking a smaller exhaust. also when it was very closed like that the engine felt very restricted and it just felt bad for the engine even if i was just poodling along.

although on freeway driving the droning lessend quite a bit even if the butterfly was only set at a half closed position.

I could maybe have tinkered with it to delay the opening event or have the thing open another pipe to the muffler or something but didn't get inspired with the initial results to warrant more cutting welding and laying under my car getting a stiff neck. so off it came.

but i did at least finish off a fine 2 1/4" straight through system in mild steel this time not SS which i don't like the sound of. very happy with the home built exhaust and i do think its allowed some more HP through compared to the silly little 2" center pipe and then 2/14 press bent mangled looking thing i had before.
will post up a few more updates soon.

sorry for all the lower case i's in the post.

Lovin the car! Is the ride height at the back what you got when you put the Datsport 900lb springs in? (In the above picture?)

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1972 Datsun 1600
1973 Jaguar XJ6
1988 Renault 5 GT Turbo

yes the 900lb springs raised it a little over the old 670's but have settled a bit more now. the KYB gas charged shocks raised it 10mm either side also!

to bring it all down a bit I got rid of the rubber spring hat and just slipped a small 23mm bike tube over the top spring bit. can't feel or hear much difference because of that but saves about 15mm of over highness.

Awesome, just what I wanted to know. Thanks!

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1972 Datsun 1600
1973 Jaguar XJ6
1988 Renault 5 GT Turbo

Awesome work MangaNOID, there is much for me to learn from your build, have started my studying!

Cheers

Matt