Engine now in - Datsun Spririt SCR Stage III 3.0 3 L28 Engine

[SeanDezart]

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.

 

[SKiddell]

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

 

[zedhed]

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.

 

[SKiddell]

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

 

[zedhed]

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

 

[zedhed]

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...

 

[STEVE BURNS]

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

 

[SeanDezart]

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.

 

[SKiddell]

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)

 

[SeanDezart]

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.

 

[SKiddell]

Apologies for the banter Mr ZedHead, I will bow out with the following

By 'get it right' I speculate that you mean optimise

No, in my books with a high performance engine there is no "optimise compromise"

Get it right, dont convince yourself otherwise

Now im going to leave the OP to tell us of his new toy as and when there is new info

If anyone wants to know any details of airboxes, dampers, pulse reflection or whatnot, lets start a new thread

(bowing out)

 

[SeanDezart]

No, in my books with a high performance engine there is no "optimise compromise"Get it right, dont convince yourself otherwise

Not sure I follow you ''no optimise compromise" as we all have different needs/applications from our high performance engines, there are different humidity and temperature levels unless for these last varied levels the fitting of an airbox reduces the delta...but then it's still (?) a 'best-solution once set-up' for general use hence my term 'compromise'.

Surely ideally if desired fro a cold and wet-day run, one would have a certain set-up compared to a circuit day on a hot-dry air day.....one setup is therefore a best-fit compromise.

We're perhaps turning around the definitio of one word here and I agree, better not to blather on Nicks' thread but elsewhere (sorry Nick).

I'd be very interested to hear what the engine-maker says on the subject of cold/hot air intake via airbox/under-bonnet filters.

 

[SKiddell]

Ill respond on a new thread Sean

http://zclub.net/forum/showthread.php?p=224041#post224041

 

[SeanDezart]

Thanks - we can all learn.

 

[strugrat]

Any update on this? Interested to know how the engine is performing?

Thanks
Ryan

 

[zedhed]

Just an update as promised - my 204Z is finally back with the Datsun Spirit 3.1 stroker installed.

The engine starts with difficulty, and the car was bogging down under acceleration or even just cutting out entirely even under power. I nearly got rear-ended at a roundabout on my first breaking-in drive when the engine cut out completely.

This has been a good learning curve for me! I've posted some pics to help others who are (like me) completely new at this stuff and may end up doing this.

So please bear in mind this thread is for newbie inexperienced guys like me tackling stuff they don't understand, not for you mechanics LOL but it may help someone.

The engine arrived with this crank timing setup from the tuner who felt the engine was too advanced. He felt the sprocket markings were incorrect. What prompted him to check this and make the changes was that the emissions seemed wrong when he did a basic tune.

So here's where it was set to:




When I explained this to the engine-builder, he got pretty worried that the engine could now be severely retarded as a result of moving the chain up a link (18 deg), plus 3 degrees at the sprocket (total 21 at crank). He asked me to send a photo with sprocket removed so he could compare with a mockup of the build he made, as well as the photos he took of my engine during the build process.(Simply amazing service by the way). He said "I suspect you will find the dowel and the market positions to be almost exactly like this (undeniable evidence that the valve timing is now severely retarded and that how I had it was correct)." Here's the picture he referred to from my engine build album:

Here's my sprocket dowel markings for comparison:



So the builder told me the car would be dangerously lean, and advised me to change it to this immediately and not to run it until reset, which I did:



This involved making a chain wedge to stop the timing chain-tensioner from popping out (a bad thing apparently) and to immobilise the crank, so that I wouldn't be working to the wrong crank timing.

Here's the tensioner made from some blue 1" plastic scrap:



Here's the chain tensioner in place about to be pushed down (it goes pretty far down). The cords are so you can pull it out again. You really need to push it down hard all the way until it can go no further or you will be in serious trouble - probably have to remove the front engine cover to reset everything unless you have surgeon-hands...



Here's a view down the chain so you can see the curved path it takes when under tension. Hopefully you'll see what I mean by pushing it all the way down.



The car is now driveable and still bogging down a bit running lean on the idle circuit. ordered some 55F8 jets then 60F8 which are starting to solve that problem. Engine is running lean higher up in the rev range but I'm going to leave that for a bit to see how things settle in.

I thought I should check the valve clearances (because the tuner said number 2 exhaust was too wide and he adjusted that), and the engine manual says they should be same for exhaust and intake, namely 0.08" - 0.2mm which they are now - what a PITA that was to untighten the locking nuts. I need to find some as I rounded off a few and messed up a spanner getting there.

I bought a timing light with dial and I'm still playing around with the timing. Also got a Gunson colortune which helped me set the idle mixtures. Used ear for synch then got a synchrometer. Turns out ear is just as accurate, and free.

Jobs to do: The carbs need work. I levelled the floats (all over the place) but I need to install vibration dampening mounts with Thackeray washers.

Oh yes - some of you wanted to see the cam, well seeing a took the sprocket off to move the chain one link I took a pic of the cam:


PS: Any fellow Z owners in Norwich? Keen to compare notes!

 

[SeanDezart]

All that and still on carbs Nick ?

 

[zedhed]

well we'll see how far we have to go really - I think it would be nice to have total control over the timing but still have the raw feel of carbs...

 

[zedhed]

OK so my next job was to raise the engine up, because the exhaust was hitting the frame rail, or rather resting on it. Here's some pics. I only noticed that recently.





Part of the problem was that my left engine mount was completely shot (the rubber had come away from the metal) which probably contributed to the lack of clerance by dropping the exhaust side of the engine.

Thanks to Peter Mac and Lawrence from Star Motorsports for spacers, and a competition engine mount for the left side. The spacers give 8mm clearance between exhaust and bay, and the harder mount stops the engine from twisting over too much when revving. Here's a pic of what Peter sent me:



Installing them was simple but awkward until I realised how to do it. Basically you loosen all the engine mount bolts and raise the engine on a jack, then slip the spacers and mount in. In practise, it takes a while jiggling the engine around until you get things lined up. I used a screwdriver to level the engine into position, by sticking it through the engine mount holes and wiggling it around a bit. I put a wood block between the sump and the jack-head to aviod denting the sump.I used a couple of wood blocks to hold the engine up in case the jack failed. I replaced the split ring washers on the engine mount nuts with nyloc nuts to stop them coming loose with vibration. The main engine mount bolts were M10 fine thread (one each side). The two bolts going through each spacer are M8 standard thread (4 total).

let me know if the images don't display

 

[Albrecht]

The engine arrived with this crank timing setup from the tuner who felt the engine was too advanced. He felt the sprocket markings were incorrect. What prompted him to check this and make the changes was that the emissions seemed wrong when he did a basic tune.

So here's where it was set to:

Maybe I'm being thick here, but I'm confused about the "tuner" you are talking about?

As it's a Datsun Spirit build, I would have thought that Eiji is the "builder" - yes? So who is the "tuner" and why was he messing around with something as fundamental as the cam timing (which - I would have thought - would have been set by Eiji as part of the build, and specific to the cam...)? Eiji knows what he's doing.

Messing around with the carbs and spark timing is going to be a complete waste of time if the cam timing isn't right. It needs to be set with a DTI (Dial Test Indicator) measuring valve lift points at degrees of crank rotation, and that also requires an accurate crank timing wheel and pointer. It's fairly straightforward if you have the equipment and the cam timing card, but I would have thought that Eiji would have done all that as part of the build.

So has somebody other than Eiji messed about with it since then, or have I misunderstood?