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1971 240z ITB install


DuffyMahoney

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Since my throttles are taper bore.  There isn't a velocity stack that looks classic and is the correct size, so I had these drawn up and cnc cut.  Sadly I screwed up a measurement, so they have to get cut again.  These are 65mm length stacks, which I think make them look better with the shorter throttle bodies.  Thoughts?  

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  • 3 weeks later...

EFI hardware is saying a Log is bad, a log is what I have done in the past.  Its all a ? They want equal length going to a collector.  

 

https://www.efihardware.com/products/1963/map-sensor-collector-kit-6-cyl-inc-hose-for-equal-length-connection

Edited by DuffyMahoney
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I would want to angle the throttles up some like the jenvey manifold since we don’t need to keep them level like carbs. It also gets them up away from the exhaust and looks better in my opinion to have the trumpets pointed up a bit. I realize it would counteract the goal of your up swept runner a bit by pointing the injector a littler steeper down but the amount of wall wetting with that short runner and the angles will be minimal. You could also just put the injector at the port like oem’s do and spray the back of the valve directly since you are making your own intake. Though I guess if you are using a e88-e31 etc head the center intake bolt hole will not be there and thus you will have a hard time getting the injector right at the port. 

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On 11/2/2023 at 10:47 PM, tioga said:

I would want to angle the throttles up some like the jenvey manifold since we don’t need to keep them level like carbs. It also gets them up away from the exhaust and looks better in my opinion to have the trumpets pointed up a bit. I realize it would counteract the goal of your up swept runner a bit by pointing the injector a littler steeper down but the amount of wall wetting with that short runner and the angles will be minimal. You could also just put the injector at the port like oem’s do and spray the back of the valve directly since you are making your own intake. Though I guess if you are using a e88-e31 etc head the center intake bolt hole will not be there and thus you will have a hard time getting the injector right at the port. 

I had an injector at the head intake, but I didn't love the looks of it.  I know that is silly, but it's how I feel.  About 30 degrees tilted up is also an option for this intake, but not nearly as good for the injector angle.  

 

I agree about tilted up looks good, it makes it look mean.  

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You just passed on a more functional port injector because it didn’t look good. Now passing on a tilted up intake because it looks good but not as functional. The wall wetting you have been obsessing on for the last three + years is not that big a deal. It amounts to an afternoon of tuning your enrichment tables and done. Think about all the American v8’s, Ferrari v12’s lambo’s and every other central v carb motor and all the wall wetting they had but worked just fine when tuned. Plus all the L6 race cars, street cars that made great power with the fuel not nearly as atomized and upstream of every setup you have abandoned. 

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13 hours ago, tioga said:

With that current fet shape we are sacrificing air flow for fuel shot geometry. Which is more beneficial? 

I have a ford racing engineer that said the runner shape (sort of S) should have little to no effect air flow in a street car, but honestly I don't know that for sure.  Lots of engines have wild air paths to the valve (my 5.0 does 180 at one point).  But lots of cars have terrible injector angles.  

 

The intake design has 2 big benefits, 1 is it gets the throttle bodies up and away from the header, then 2 is the injector spraying down the middle of the runner. I personally think it looks good.  I wished the FET wouldn't have been so poorly made.  It would have been a much easier project.  

 

One thing I haven't talked about a lot is cold starts, and working with automotive engineers, one theory we have been talking about tough cold starts are from intake walls being cold and my poor injector angels, so higher wall wetting and fuel puddling.  Then fuel puddles going into the cylinder, thus causing cold start tuning issues.   This is probably my least favorite part of ITB so far.  Rough cold starts.  I am hopeful that spraying down the middle of the runner helps all of this. But time will tell.  

 

Honestly my first intake and throttle setup ran the best (jenvy/ harada).  I have also gotten much better at tuning, so I kind of wish I had that setup still to see how I can get it to run.  Smartest ITB intake would have been Larrys intake with the injector spraying the valves or the Whitley tune intake.  

 

Also haltech is moving away from transient throttle in favor of Map prediction, which I have been told is much much better at cold starts and overall light throttle input tuning.  Tuning transient took so much time and I didn't have it perfect.  

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  • 4 weeks later...
Something sexy to start the week off with. This is a stainless fuel rail for my ITB setup. Expertly crafted by Michel Vienneau! It features injector safety clip stainless cups, built in AN fittings and polished. I’m hopeful it being smaller will allow me to clock my injectors and hide my wiring a bit.
Now I can’t scratch it. Michel is a metal magician!

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19 hours ago, ksmithgall said:

What fuel injectors are you currently planning on using?

This is Steve from EFI hardwares favorite injector for the L with his ITB, their spray pattern was used in the creation of my intake, with the goal of injecting down the middle of the runner.  

 

https://www.efihardware.com/products/2720/Bosch-Injector-347cc-3Bar-12-Height-EV14-E85-Compatible-with-Extended-Nose

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