Ssaga
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Posts posted by Ssaga
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This dyno curve is quite typical. Transition idle jet to main jet. You can change this a lot with keith franks hypos(idle) and obert e-tubes(main) or the new bb tubes(main). Pulls like a injected engine afterwords.
Are you running any of Keith's jets?
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Does seems like a common weber dip then, anyone here that run with Keith's jetting?
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Contacted the dyno store today, they where out all weekend supporting rallycross competition,so hopefully on Monday I will have the figures.
Regarding the 3500 dip, should I try to change the w low speed jet to 45F8 instead. Regarding the lean on top maybe go down one size in air corrector?
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Engine goes really rich between 3,100 to 4,000. Lambda values by curve appear to be down in the 0.70 range. Far too rich. That's in the mid 10's for AFR.
Then Curve goes lean towards mid and top end. Lambda 0.93 = 13.67. You want closer to 12.8 to 13.1. Some head designs want even richer. You didn't say what Cyl head you are running. That matters a lot.
Se if you can get the detailed Text print out from the Dyno operator. You'r leaving HP on the Table. Fuel curve can be refined further.
If this is for a street engine, I'd try 36mm chokes. 38MM are a bit large for 45 Webers. More a Race size only. May clean up the fuel curve a bit as well. And you'll improve bottom end Torque and driveability.
Lambda to AFR conversion chart. Gasoline standard at 14.7 Stoich:
Really nice input:)
When you wrote choke 38, i started to doubt. Just ran out to the garage, it´s 36:).
Using N42 head.
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No you'll usually lose HP just before detonation. Very sophisticated OEM dual knock sensors can run just at the onset of " light pinging", That's how they maximize fuel mileage. But that's at light load. It's dangerous to try try that strategy at Maximum load. Plus the modern knock sensors will " hear " the pinging well before you can hear it.
Turbo motors can swing so fast into detonation that you really need WB Knock sensors on a Dyno and most good Dyno operators will use Det-Cans to monitor for the slightest detonation during a run.
AFR is one of the single most important Parameters of any Dyno run. Without that info, Dyno chart reading is just guessing. See if Dyno operator has that info.
Do I need AFR when I got lambda?
I thought AFR and Lambda where two different ways to basically measure the same thing?
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M
Did you monitor the AFR?
Off topic, did you ship the engine to Sweden?
Dunno regarding the AFR, maybe logged in the dyno logs.
Built the engine myself in Sweden, however sourced the parts in US.
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Thx för all the comment
Do you think a bigger can would improve?
I was leaning towards more headwork??
The dip at 3500 is only avoided by giving gently throttle until moving past this dip.
My distributor has an 8,8 mechanical advance, so 17 then, I'm a bit confused regarding this.
Firstly, the initial advance is set at 11 but is maxing out at 32, this indicates a mechanical advance at 21, but I got 17.
Secondly, when putting more and more advance I never got any detonations, simply lost top effect. I always thought you put more and more advance until you detects detonation then you retard it a bit.
Have no AFR fig
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Might add that this is figures on the crank.
Think the scale is the same, divided by 100 then you get 0,93.
You are correct there is a quit bad drop at 3500, to rich.
Worked on that a bit without any good result.
Carb is jetted:
38 choke
F15 emulsion
150/180 main/air
50F8 low speed
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Just got back from a dyno session yesterday.
Would be great if you guys could give me some feedback on the figures
It´s a 280z-75.
-Engine Spec
-2.8l, 0,5mm oversize flattop pistons with outtake for the valves
-Datsun spirit cam, 290 duration camshaft .490 lift
-Mild Head work, match ported towards intake and Header.
-New stock size valves and complete valve work
-Z-story Header and full 2,5" exhaust system.
-Lightweight flywheel
-Triple Weber 45
-MSD 6AL ignition with zx distributor.
- Compression 10,4:1
Ignition is right now at 32 total advance.
Setting towards 37 I lost about 10hp, however no detonations, so then moved it back.
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I have almost same problem.Have double, trippelchecked everything.
Cam and crank at TDC, distributor spindle at 11:25, can't reach within scale for
timing. Also tried to change a notch on the spindle by lowering the oilpump. Still not possible to reach within scale.
However the difference when changing notch on the spindle is that the timing goes from excesive retard to excessive advance.
My next thought is that the mechanic advanced springs are old and worn, letting the weights spin out to easy.
Pictures show the spindle positions I tried.
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Thanks!
Right now I´m having problem finding the correct timing.
With distributor aligned as in the pictures I was no able the reach the proper advance, couldn´t ever reach 0 degree.
Moved the Oil pump shaft one notch, now I can´t retard the timing more than 16 degree BTDC..
Feel unlikely that there is a notch inbetween.
The shaft sits perfect at 11:25.
However the car is very hard to start and as said I cant retard more than 16 degree BTDC.
It´s a 280zx dist with MSD 6Al.
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I´m right now on the final stage of my complete engine rebuild.
Before engine start I´m double checking the timing alignment.
I however seem to miss the V shape mark on the sprocket(aftermarket OSK) which makes me a bit
hesitant.Below pictures show the alignment as i sits right now, can anyone please feedback
whether it´s aligned or not.
Car is a 280z -75.
Chain, cam and sprocket are new and the the marking down at the crank is aligned.
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Also been inte ITM, however no real feedback so I´m a bit careful.
Seems that NOS Fuji Intake valves are available on EBay.
Harder to find Exhaust.
There is a set of Exhaust valves branded Dokura, anyone have experience in these?
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I used stock-replacements from SI for my rebuild.
Did you go for stainless?
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Thx for the tip, just changed the headline.
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The problem is that the actual valve shaft is a bit worn,so I will replace all.
Question is ITM,DNJ or any other aftermarket brand
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Looking for a set of new intake and exhaust valves for my 280z. Ambition is to buy stock size high quality, I'm however a bit confused which brand I should aim for.
Grateful for advice.
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I´m searching for Conversion brackets to support the
assembly of 280zx calipers on my 280z.
Same as in below thread.
http://forums.hybridz.org/topic/49661-z-car-rear-disc-brake-conversion-brackets/page-3
They however seems to be hard to source these days.
Grateful for tips where they can be found or if other conversion brackets
will support 280zx calipers as well.
/Henrik
Cam card figures vs measured figures
in Nissan L6 Forum
Posted · Edited by Ssaga
I while back I took my car, (280z) to a dyno the result, (discussed in separate thread,http://forums.hybridz.org/topic/127636-thoughts-on-my-dyno-result-280z-triple-webers/?hl=%2Bdyno+%2Bresult
I contined the investigation regarding the strange figures.
I surely have jetting isusue, I however also discovered that my cam was way to retarded.
After several measurements with degree wheel and indicator clock I decided to move the
cam one notch forward.
After this the measurements look quit ok, would probably be a even better with adjustable cam sprocket
After advancing the cam these are the figures i got.
Max lift intake lobe at 105 degres, approx 12,3 mm, defined max lift according to cam card 12,57 mm at 104 degreess
Max lift Exhaust at 111 degrees, approx 12,3 mm, defined max lift according to cam card 12,57 mm at 108 degreess
Intake lift at overlap 4,5mm
Exhaust lift at overlap 3,5mm
Below are figures I measured when camshaft mounted in engine.
At 0,05 inch.
Exhaust opens 65 degree BBDC
Exhaust closes 17 degree ATDC.
Intake opens 27 degree BTDC
Intake closes 51 degree ABDC
Overlap 44 degrees
Overlap according to cam card 32 degrees
The Duration I get with measured figures
Intake 258 degrees
Exhaust 262 degrees.
Figures according to the cam card.
Exhaust opens 50 degrees BBDC
Exhaust closes 14 degrees ATDC
Intake opens 18 degrees BTDC
Intake closes 46 degrees ABDC
Duration according to cam card.
Intake 244
Exhaust 244
What I don´t understand is the differences in Duration and overlap when comparing to the cam card, this is very strange to me.
I´m measuring this with valve play at 0,08 inch as stated in cam card and at the valve retainer.
There are certainly some degrees here and there that are incorrect, but as whole I think this is correct.
The big picture is showing a quit a big difference in Duration and overlap.
I´m I missing something when measuring?
The feedback I get from supplier are more aiming towards that the Max lift should be at the correct timing, and not
focus on Duration and Overlap.
For me this is a bit strange, I would like to know the actual Duration and overlap of the cam in the car.
Grateful for any help.
/Henrik