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  #16  
Old 21-03-2015, 10:55 AM
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...The CR is seriously high, if it's on carbs it'll probably run-on when the ignition is switched off.
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Originally Posted by SKiddell View Post
Why ??
Just going from personal experiences (as usual). My old car and my DJ car (10.5:1) run-on when hot i.e. 'dieseling'

http://en.wikipedia.org/wiki/Dieseling

I know the above suggests that it's a hot-spot that's causing it but I've only ever had this on high compression carb engines. Obviously FI engines cut off the fuel but as long as a carb engine is running it'll keep drawing a small amount (idle) fuel.

I have had to stop both engines by stalling them (I did yesterday).

If you can tell me how to prevent this I'm interested.
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  #17  
Old 21-03-2015, 11:28 AM
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Hi there,

Is a harmonic balancer essential if the pulley has already been balanced as a unit, and what kind of revs would this become an issue?

also wouldn't the installation of balancer require re-balancing of any other components, or is that a simple bolt-on affair?

I'll get in touch with Mike, If you have any detailed pictures of how these things are installed I would be greatful!
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  #18  
Old 21-03-2015, 11:50 AM
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I should explain the harmonic balancer I have isn't fluid filled it's got some kind of polymer fill - I can't actually remember what model but it's something like this here so I'm not sure if that will suffice or I need something more expensive. Remember this is a fun car not a drag racer, well at the moment
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  #19  
Old 21-03-2015, 04:25 PM
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Originally Posted by SKiddell View Post
As for a crank damper, make sure you get a good quality one (not the original Nissan unit) as crank harmonics are very prominant at certain revs and will kill an engine if not managed, Sean Dezart on here sells a very good fluid damper for good money (an ATI one can cost 500 quid)

As for an airbox, the reason I suggest it is that I did alot of work to develop one (many rolling road sessions)but I dont sell one........MJP does and I can recommend it, but its not a quick fit, (few good things are) if your going to do it, get Duncan to fit t now. Using "socks" is very old school and is an elastaplast as open trumpets suffer badly from reflected pulses of the inner body work and WILL lose you power and creat flat spots ........I have many many dyno sheets to prove it and a rolling road bill tht would make you cry, I use adjustable length trumpets inside and airbox so I can tune the inlet tract length.
Thanks Steve. And the airbox works too.

Quote:
Originally Posted by zedhed View Post
Is a harmonic balancer essential if the pulley has already been balanced as a unit, and what kind of revs would this become an issue?

also wouldn't the installation of balancer require re-balancing of any other components, or is that a simple bolt-on affair?
Not essential......like certains types of insurance in ones' life but grateful to have it on the 1x occasion that it's needed. The bitch is you'll never know it saved your engines' life...it's only the breakages that're recorded .

THAT'S the beauty of a fluid damper, it adjusts itself to the engine fitted upon.
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  #20  
Old 21-03-2015, 09:32 PM
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Really really interested in how this turns out and what power figures you achieve.

I spoke to Eiji in some depth last year and he seemed a nice guy and, very knowledgeable as already mentioned and excellent prices I thought.

He mentioned he was also speaking with someone else in the UK.

I am still considering Datsun Spirit but I found it hard that the engine wouldn't be run on a dyno before delivery to me, so will probably be going a different way (but hopefully just as nice).

Best of luck and keep us posted!
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  #21  
Old 21-03-2015, 10:32 PM
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Nothing at all against Eiji but I got invloved in a case of a reclammation via ebay and paypal for a 'close-ratio, direct gearbox' being sold via him which turned out to be the equivalent of a std 240Z euro 5 speed.

Knowledgeable upon Z performance and I admire his kit I have no doubt but USA Z-orientated - I have no doubt also.
I think he is in a priveleged position to have benefited from translating a lot of source material from its' original Japanese.
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  #22  
Old 22-03-2015, 02:53 AM
SKiddell SKiddell is offline
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Is a harmonic balancer essential if the pulley has already been balanced as a unit,
Absolutely yes, all objects and systems have natural resonant frequencies, once reached they will vibrate in harmony and it can destabilise any applied "balancing" to the point that it will destroy the structure......an example is bridges that have been destroyed by natural forces in tune with thier natural frequency

Your existing damper may be sufficient, elasomer dampers are equally as good as fluidic types in the right application.....more data needed
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  #23  
Old 22-03-2015, 08:47 AM
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I felt my choices for a premium / custom US built engine were either Rebello or Datsun Spirit. I just got through to Datsun Spirit first, but I'm sure I'd be equally impressed with Rebello - hear there are Rebello engines out here in the UK already and all owners are very impressed. Not sure if mine is the first Datsun Spirit engine in the UK or not?

Anyway, I'm sure we made the right choices for the build, and Eiji certainly didn't seem concerned about the dampener side of things. I found the communication excellent, but then it should be when you're spending around 11K USD.

Frankly I've never done business with an engine builder who communicates so well, and provides good reasons for choices made during the build, whilst helping you spend your money wisely. Some other (non-Z) engine builders I've done business with make you think you're dealing with some kind of witch doctor. The engine is a black box, and they can get pretty arrogant about their own "special way" of doing things, even to the point of hiding their "special formula" - plus you need to wait ages for the ones in demand. With Datsun Spirit it was all very clean, scientific and reasoned out - more like dealing with a true professional. Simply gave my requirements i.e. Torque, grunt and fun driving with an emphasis on reliability. Time-scales are stuck to as well, which is unheard of in the UK.

Anyway, we will see how it goes - the proof is in the pudding

By the way, I got a spreadsheet of clearances and other data, so if anyone want's that PM me, because I can't figure out how to attach a file on this forum.
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  #24  
Old 22-03-2015, 10:26 AM
SKiddell SKiddell is offline
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I felt my choices for a premium / custom US built engine were either Rebello or Datsun Spirit.
If I didnt build my own engines, I would chose Datsun Spirit EVERY time

Your $11K is a fairly good buy for the package you have, for instance my race head, steel crank/ rods cost that !!!!!!!

regarding crank dampers, whilst Eiji may not be bothered I would take aditional council from others its a complex subject not often understood by even engine builders
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  #25  
Old 22-03-2015, 12:48 PM
zedhed zedhed is offline
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Ok good to know thanks for the info S - so back to air boxes, I get that they ensure cooler air flows in and understand the need for cool air and all that, but don't understand how a box can ensure the rear cylinder gets the same amount of air as the first in that tight flat space with feed at one end, nor how atmospheric pressure can be maintained. Also I don't understand why reflected pulses are any less off bodywork which is further away than the inside of the filter cover, which is very close and orthogonal to the trumpet mouth. Surely long trumpets like the ones on my engine serve to increase pressure and velocity by restricting the flow through a smaller diameter aperture. Why would socks not reduce reflection being a soft surface with "give" like a microphone muffler? What am I missing here?

Perhaps I just like the look of those stacks eh? LOL
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  #26  
Old 22-03-2015, 12:51 PM
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Just to clarify by saying "I don't understand how atmospheric pressure can be maintained" I meant because the pipe at the front of the box seems smaller aperture than the box itself...
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  #27  
Old 22-03-2015, 01:11 PM
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Originally Posted by zedhed View Post

By the way, I got a spreadsheet of clearances and other data, so if anyone want's that PM me, because I can't figure out how to attach a file on this forum.
When you are making a post scroll down to Additional options
Click on to Manage Attachments to open
and then you can either upload a file from your computer or upload a file from a URL
Hope that helps
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  #28  
Old 22-03-2015, 04:26 PM
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so back to air boxes, I get that they ensure cooler air flows in and understand the need for cool air and all that, but don't understand how a box can ensure the rear cylinder gets the same amount of air as the first in that tight flat space with feed at one end
Can I be the black sheep and say that 'the need for cold air' depends upon your needs. Steve and others are counting the last 5-10bhp and for specific purposes. I beg to submit than a airbox isn't the only method by which to obtain cold air and by experience, it's not essentiel.
For info my on-the-go L31EFi will have K and N airfilters and after summer I'll be able to come back to you with some r-road figures.
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  #29  
Old 22-03-2015, 04:49 PM
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Steve and others are counting the last 5-10bhp and for specific purposes
If I had spent $11K on an engine I would want to get it right, never mind tuning for a specific purpose.......I guess I just come from the David Vizard/Dave Walker school of tuning...."get it right, dont talk it right"

K&N air filters will not stop 50 degree (C) air entering your engine and temps measured on a mild summers day will be in excess of that
RR experiments that we did a couple of years ago showed a differential of over 20HP versues open trumpets plus the almost complete elimination of the ever present torque hole around 3500 rpm

ZedHead maybe the nuances of pulse reflection (read some of my technical articles which have been drawn from some of the best NA tuners in the world) might be tricky and vague (although they are accepted automotive science fact) but surely you will understand that the warmer the air the less dense it is, the less dense it is the less oxygen is available, the less oxygen the weaker the mixture and the less power is made at the risk of valve and piston damage.
Consequently tune the engine when cool and it will be out when warm and vice versa

With a cold air box you minimise the delta

These are of course only my opinions backed up with countless rolling road sessions several hundred 1/4 mile runs, the verification of the tuning God Dave Walker and the OCD of an engineer

You chose, im just trying to help (not sell anything)
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  #30  
Old 22-03-2015, 05:43 PM
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Originally Posted by SKiddell View Post
If I had spent $11K on an engine I would want to get it right, never mind tuning for a specific purpose.......

K&N air filters will not stop 50 degree (C) air entering your engine and temps measured on a mild summers day will be in excess of that

With a cold air box you minimise the delta
I don't doubt any of your date and shared experience of those quoted.

Like I said, there are other alternatives to receiving cold air into the engine and eliminating the effects of hot air under the bonnet and especially running through the radiator.

By 'get it right' I speculate that you mean optimise ? And that with an airbox the setting up is the best set-up for all future meteoric conditions...save extremes of atmospheric pressure.

I'm also not trying to sell anything.

And I will still come back with my data later.
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