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Datsun L24

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Humming
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Datsun L24

Post #1 by Humming » Thu Jul 20, 2017 2:03 pm

Hey all, so aside from my Ford 4.9 I have one other inline 6 in my life. I have an L24 out of my 1973 240Z. Any other foreign six fans here?

My plan is to convert it to Port fuel injection, electronic ignition, and if I can afford all the machining, build a set of ITB's of my own design. I'm going to Port the head and bore it out a little. The intent is to make a motor that makes it's power high in the rpm range and revs quickly.

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bubba22349
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Re: Datsun L24

Post #2 by bubba22349 » Sat Jul 22, 2017 8:22 pm

I am a fan of them! Mostly used to hot rod the L20B's (Inline 4's) but also worked on a few of those Z six'es too. :nod: :thumbup:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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xctasy
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Re: Datsun L24

Post #3 by xctasy » Sun Jul 23, 2017 1:31 pm

Wouldn't bother with Fuel injection.


Japan, German, English. Nothing beats a nice fat 390 CFM 4BBL....


http://vb.foureyedpride.com/showthread. ... s-FINEST!!!

xctasy wrote:That's right. And i tied it in with the dark aspects of the band Queen for this reason...BUT I'm thinking perhaps I was wrong, maybee Black Sabbath was when the electrics went on holiday...



My 1958 PA Vauxhall Velox had enough American AC Delco parts in it to function even if the Lucas igntion started to go on Holiday...but I've dabbled with the Dark Side of Lucas enginneering...

See how others do it...http://www.bsccoc.ca/2012-FrechettesCrestas.php


pc79, I'm with you on performance, my 19.5 second quarter mile Mustang was the most fun car I've had. 15.9 seconds in my 1984 250 Falcon was not nearly as fun. But American cars are so reliable. A little 1435 cc A series can poke out 145 hp with one 45 DCOE, so why oh why do you even need blower on a 2.5 when it just needs nice little 390 CFM 4-BBL like all killer 240Z's and BMW sixes end up with.

http://bringatrailer.com/2012/09/29/bat-exclusive-1971-datsun-240z-race-car/

Image




And BMW'S...http://www.seniorsix.org/faq/2_4bblconv.html

Image

The English needed to take some stern simplicity lessons from the US of A...
Image
XEC Ltd ICBE's Inter Continental Ballistic Engines-
FAZER 6Bi (M112 & EEC5) or FAZER 6Ti (GT3582 & EEC5) 425 HP 4.1L/250 I-6
FAZER 6V0 3x2-BBL Holley 188 HP 3.3L/200 I-6 or 235 HP 4.1L/250 I-6
X-Flow Engine Components Ltd http://www.xecltd.info/?rd=10

Humming
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Re: Datsun L24

Post #4 by Humming » Mon Jul 24, 2017 1:53 am

Just curious, why is a carb so inherently better than a proper port fuel injection set up?

Electronic ignition with coil on plug and port fuel injection should make all the power a carb can, and be more efficient.

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xctasy
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Re: Datsun L24

Post #5 by xctasy » Mon Jul 24, 2017 3:55 am

Humming wrote:Just curious, why is a carb so inherently better than a proper port fuel injection set up?

Electronic ignition with coil on plug and port fuel injection should make all the power a carb can, and be more efficient.


L series Nissan sixed have a weird bore spacing...3.96 in the inner cylinders, 3.76 on the outer two, because its actually an OHC conversion of Kent /105e Ford 4 cyl engines (What the L14/16/18/20/Z20/Z24 really are). The i6 are based on Ford Kent/Zephyr Zodiac in line 6 and BMW m20 style tooling and bore spacings, but the Japanese increased the inner cylinder bore spacings.

The dormant cylinders on I6's are every cylinder except 5 and 2.Thecylinders that kncok, detonate or get damages the most on I 6's like the L24 and Log and 2V Ford 250's are 5 and 2.

The L series sixes like to be fed from any other cylinder port than 5 and 2. 5 and 2 are the common cylinders to detonate and knock, so they are the ones best fed. A carb that has a flow bias that feeds the normally starved 1, 3, 4 and 6 gains power.

EFi works on a linear, the illusory story book idea that all the flow is lamina, and each cylinder needs a democratic right of even supply....in fact, I6's aren't like that at all, and each cylinder needs to be Morse tested to find which ones need more feed. Like an old rule about manageing to get results, you don't treat all cylinders the same way, you find out the lagging ones, and attempt to raise them all to the same standard.


It is normally, comparing, say a well sorted Port on port injection engine with EDIS/Coil on plug/Waste spark ignition, it should be night and day, especailly when cold.

The issue is that ignition and air fuel control frequently are influenced when an engine is modified....automotive engineers do the ignition system first, then the fuel delivery system, and cam, head and then go back to the igntion in steps.

Some engines really don't like fine atomised fuel, and specific power drops, but fuel consumption improvements then require ignition system changes.

The heat factor from multiple carbs heated up by the exhasut form a non cross flow head...it may mean Zee's favour one small carb with a really good intake instead of independent runner sysyems.

A series 1275 engines are non cross flow, and hate fine fuel atomisation....fat Weber 48's really make those things make big power, 145hp net at 7000 rpm for a good bored out 1275 (1435 cc). Put Algon Injection on it, and it looses power, and fuel consumption stays the same.

Where are independent runner EFi systems on Big Block Chevs...nowhere compard to a really good single 4-bbl Dominator. In theory, EFi with port on port delivery should surely be able to dialed in to give an engine what it needs....and the result should be on a dyno. In practice, a lot of money is spent, and other non electronic system out top programmed Fuel injection.

This is not a vote against EFi, I like it, but most EFi tuners have a standard system for bench marking EFi development....its called...a carburettor!
Image
XEC Ltd ICBE's Inter Continental Ballistic Engines-
FAZER 6Bi (M112 & EEC5) or FAZER 6Ti (GT3582 & EEC5) 425 HP 4.1L/250 I-6
FAZER 6V0 3x2-BBL Holley 188 HP 3.3L/200 I-6 or 235 HP 4.1L/250 I-6
X-Flow Engine Components Ltd http://www.xecltd.info/?rd=10

Humming
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Re: Datsun L24

Post #6 by Humming » Mon Jul 24, 2017 9:20 am

What if I include cylinder egt probes on each exhaust runner? While not a perfect plan, this should at least get me a little bit of an ability to tune fuel to each individual cylinder.

The car this is going in will get put away for 6 months every year. I plan to use a fuel stabilizer, but even stool don't really want to fight with a carburetor every time I get it out of storage.

I'm curious about your comments about cylinders 5 and 2. Isn't that due to being carbureted in the first place? Wouldn't one injector per cylinder injected right at the port on the head basically do the same thing, only better, aka even out the fuel to the rest of the cylinders instead of having two rich cylinders? Or am I missing what your describing?

Don't want to come across as contrarian, just trying to learn.

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Re: Datsun L24

Post #7 by xctasy » Mon Jul 24, 2017 12:56 pm

The developments in the 70's were from wide open fuel air ratio checks, color tune idle, and BSFC dyno tests. And some thinking from race engineers who then got to repair them. Like Jet turbine engineers, they soon became top of the pile on understanding what parts of the system did he work by what parts got damaged.

Modern fuel delivery, its wide band O2, and some pyro work. Hondata and other companies spend a lot of money allowing cylinder to cylinder buffer changes...why would they do that on an EFi engine? Answer....because it is not a House in the Sun of accuracy like people think. There is a pace for scrable cams, differential static and dynamic compression ratio changes and different LCA's and individual cylinder to cylinder spark timing due to a lack of flat fuel curves emanating from simple issues with air flow to each cylinder.

Wet flow systems is carb engines made it easy, with fuel injection and dry air flow, it requires flow net and termatic diagrams to islolate poor fuel air distribition issues. Atmosing fuel before it hits the intake valve is a great idea, but cylinder flow Homogeneity and paddle wheel intake spin is what sets appart great engines like the LS Chevs appart from "Pi55 and Dribble" conversions.


From what I've seen with the EFi Falcons, no. EFi has poor cylinder to cylinder flow, especailly the Ford 5.0 EFi, and the reason most modern EFi and dynamic inlet runner, VCT, and individual cylinder to cylinder fuel to ignition timing exists.

The one 02 sensor is designed to allow more than 10% flow variation Bosh or Siemens injectors to operate as if they were 1% accurate, thats what a Closed loop by PWM fuel system does, it uses the 15.1:1 real or 14.7:1 theoretical air fuel ratio from a resistance thermometer to alter upstream pulse width. In fact, the cylinder to cylinder variance upstream is going to be way different between the six cylinders.

Clamp on header EGT's are such an easy way to tune.

The original Datsun fuel system was very efficient, and the two carb on six inlet system was fine if in good shape. Its why Jag downgraded to twin SU then twin Strombergs, triples didn't have better fuel distribution than 2 carb set ups. Single carb MGB GT's and Midgets on log intakes, the fine atomised Zentiht Strombergs on siamese port heads, you didn't gain better air fuel distribution.

The L series engine, its got some issues.

The modern fuel really doesn't like to be sitting around no matter what system you use. Octane ratio drop is huge, but even 83 octane that started as 91 will work if its cleaned of its ethanol or any parcipitate. Fuel draining dry, probably worse.

https://www.youtube.com/watch?v=z3gU75lZ9gc
https://www.youtube.com/watch?v=zJtwz0h-ojQ
14 year old gas, https://www.youtube.com/watch?v=M352Jw7Ph64

or pulling out ethanol all good ideas https://www.youtube.com/watch?v=onCG7mIprfE

I love simplicity in fuel delivery, damage to a fuel system happens between dry and submerged states, and I recomend a fuel stablizer or conditioner, and then a conclusive, visual fuel clean. I love race gas fuel spikes to old cleaned gasoline, you can reboost dead, stale gas.


Back to results....its the lb-ft peak torque readings and peak power rpm readings that must be the litmas test for deciding to go EFi.

Modern Modular Fords are at the 1.64 lb-ft per cubic inch level, the old BDA Ford 4 valve per cylinder engines, 1.39 lb-ft per cube, which was a test for good intake design. Peak power levels, I don't use Brake Mean Effective Pressure (BMEP), I use Phil Irvings hp per rpm per cubic inch.
There needs to be a proper 1600 rpm gap between the peak torque and pea power rpm levels, and an ability to over speed 10% past the power peak.

This is classic 350 Fuelie head/Cleveland 351 stuff, engines that had the right combination of peak power without loss of power at high rpm. EFi engines are just pumps, and need to pass the same tests as carb engines of yore to prove the worth of injection.

All people who run dynos are looking for peak torque and peak power improvements over the rev range, but the shape of the curve and how it operates in the transient stages of a race are what is important.

As a lab techncian, I remember my boss saying, Dean, look at the data. Tell me what it is telling you compared to the text book theory. Someones going to ask the same thing of you.

If you rank an engine with venturi sizes, no one can beat these two charts below for peak power. It sets a glass ceiling.

It does drop off in really big engines due to phsical size restraints, and some single 4-bbl set ups out do independent runners in smaller engines because of cylinder to cylinder issues and geometrics of fuel air mix flow.

viewtopic.php?f=5&t=71515
http://victorylibrary.com/mopar/intake-tech-c.htm#ir
IR manifolds, where each cylinder can only draw from one barrel, offer the absolute best idle quality, throttle response, tolerance of high-overlap cams timing, and allow accurate tuning of intake length for maximum torque.

Even using the largest common IR carburetors (Weber 48mm IDA with 45 mm venturis) the maximum cylinder size is about 45” (or 70 HP, whichever is less) barely enough to supply a 360” motor @ 7000 RPM

Completely separated IR carburetors for a 500” motor (62.5” cylinders) @ 10,000 RPM would require 63mm(2.47”) venturis!



For other situations, the glass celing is here:-

Image

Image

For torque, EFi is an easy gain if set up correctly.


viewtopic.php?f=3&t=35573
Image
XEC Ltd ICBE's Inter Continental Ballistic Engines-
FAZER 6Bi (M112 & EEC5) or FAZER 6Ti (GT3582 & EEC5) 425 HP 4.1L/250 I-6
FAZER 6V0 3x2-BBL Holley 188 HP 3.3L/200 I-6 or 235 HP 4.1L/250 I-6
X-Flow Engine Components Ltd http://www.xecltd.info/?rd=10

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