MANIFOLDS/ intake problem

[DYNOED250]

Just after some advice from some of the guys on here....
If u can see the picture of my manifold set up on my 250 then where half way there to my question..


On the weekend i took the cortina out for a spin (last time before auto goes in) , It was misfiring on 2 cylinders it sounded.. so i pulled the plugs out and found somthing very interesting...

The plug closest to the Throttle bloody was a very very light brown (almost white) the plug furthest from the throtle body was black and nearly totly fowled.. the plugs were a shade differnt from front to back with the plugs getting lighter in color as they got closer to the throttle body.


Im thinking the manifold its self isnt flowing enuf air in the plenim?... is this posible.. its the only reason i can think for the plugs to have this differnece..

As the injectors all fire the same milli seconds of fuel, so the only thing that would cause cylinders to run any leaner or richer would be air flow..

Is it time for me to make a 6 40mm throlle bodys manifold???

 

[addo]

You are losing airflow for a variety of reasons, in my opinion.

The incoming air is not pressurised, so you only have the natural velocity (which may not be much depending on vehicle speed). Then the pipe size is very similar in sectional area to the plenum; this seems odd to me. Also, the convoluted flex tubing is a known obstructor of airflow. It's all just running out of speed futher from the TB.

What if you chose a tapered pipe, that started say twice the diameter and turned the corner with a mandrel bend, still tapering? Use a turbo style plain rubber sleeve to connect the motor to the intake.

I think if you were just to run open at the throttle body, a lot of the unevenness would go. Shame it's not good for motor life!

 

[DYNOED250]

i have removed ... the ducting in front of the throttle boddy.... ill drive it for a few days and see what results i get

 

[xctasy]

I decided a year ago not to tell you or George about the problems both of you would have with the intake fittings on your Cortinas.

There were two reasons.

Firstly, you two guys have crafted so much enginuity with the intakes for your EFI engines. George used a pewter bear mug, and you used a U-bend, and both are great ideas.

2. Both allow air to go into a well crafted EFI system, and having a tosser judge and suggest improvements would have been a bit rich.

There is every evidence that I could suggest a way which will improve air flow at any revs by 10 to 20% with some ease.


Here is how to do it.

In your case, it is basically becasue the stock throttle body, bare, with with no extension, would flow 100% of the peak air flow. Adding the U-tube would reduce it to 95% or even 90% of that peak flow. Adding a custom intake structure of the best type given your space resitrictions of the fire wall will givea flow of at least 110% of the flow of a bare throttle body.


Okay, I'll say the existing tubing reduces the peak air flow by at least 5%. Waht you can do now is add a proper hyperbola intake made of epoxy or alloy plate. This follows the kind of Stub Stack set-up you'd have on a Mini HS4 carbs.

This is shaped to make the air flow curve into the high pressure central zone from the low pressure, large anular area around the throttle body. That will raise the airflow to 110% of the flow of a bare throttle body.

The is still no air cleaner, which isn't sensible, so you then add a big oblong 4.5" minor axis, 9" major axis 'oval' of metal which is about 60 thou thick. Steel or alloy plate. Place it 0.75" away from the surface of the throttle body inlet. Then add an air cleaner to it. Like one of these.

or this.

What this does is prevent too much rough air flow occuring. The key is to allow the air flow behave in a linear manner, so any vorticies are removed. If you add a flat place close to the stub stack, it will do an very good job with limited space.

If you duct some cool air to it, it will give the ultimate in performance with a consdireable gain in flow

 

[addo]

Oi mate, what's happening with this?

 

[DYNOED250]

hahaHAH.. FUNNY U SHOULD ask this actually.... My nice billet Alloy romac balancer decided to come loose, and the prick was making a massive sound. Pulled if of and its got a nice big crack down the center of it... arh well it was nice while it lasted. THe cast iron balancer will be going on not wasting that sorta cash again.


Any hows back to the topic.. ill pull the plugs out to morrow moring and post picks up right away.. ITs been driven around since last time without anything after the throttle body. So it will be interesting to see if its any differnce..

 

[addo]

Was that the full alloy balancer, or the alloy/steel hybrid? Why not see what Romac have to say? (I know what Ross will say. )

Cheers, Adam.

 

[DYNOED250]

full alloy

 

[DYNOED250]

[img=http://img408.imageshack.us/img408/9206/dsc014186is.th.jpg]


Top plugs are the first set with intake ducking and pod air filter
iT SEEMS to of improved over all alot leaner ( due to no restrictiin in intake now i gues and greater air speed (i know there differnt plug types) I ran the ZGR6B11's as i decided a cooler plug was in order becase of the rear plugs running so hot.


And this is the romac balancer i may get another one but steel center this time.. im still a bit pissed of about it. I think its due to my one fault rather then faulty construction. When the clutch shit its self every thing vibrated ultra bad but i drove it for a while... im thinking mabie the vibrations had there effect on the bolt in the crank and mabie worked it loose( id like to think that) but its prob wasnt tight enuf to start of with

 

[addo]

Yes, a definite improvement. What if you graded your plugs to suit each bore? Also, can you fit some kind of little pod filter on the end of the TB?

A really weak supercharging might do it, otherwise.

With that balancer, the only things I'd consider may have happened are: too tight on the crank, and too much load on the outer pulley.

 

[aussie7mains]

I think you you might be overlooking a few more obviuos things like:-
plugs leads dizzy etc, pluds not firing will be black and sooty.
Air leaks in the weldes etc. these will cause a miss usually at low loads and idle. Dicky injector if one is dirty or leaky it will miss.
What ECU tune up do you have if its too rich it will soot up plugs too the point they will miss.
Best check any of these before you start doing anything more radical.
Always check the simple things first

 

[DYNOED250]

All the plugs leads cap rotor, were all new, brand new injectors, every thing. It idles fine but was breaking down under load. If u look at the plugs at the top of the pick the problem isnt that there black its that it slowy gets leaner on each pot till the one closest to the TB which is the leanest this carnt be tuned out as i have the both ends of the scale . Removing the Intake defently helped with the plugs. And itl be going back on the Dyno for a re-MAp.

As far as intake after the Tb, execute, do u mean that even if i had a flat plate around the TB so that the air wasnt rushing in from the sides and around the end of the TB then going in as in a "U direction it would flow a fair bit more??? Not sure if that makes sense
Like i mean AIR thats flowing along the out side of the throtle body hitting air thats flowing directly into the tb.... So either a flat surface around the front of the TB or a big Belmouth type set up ??

 

[wagon]

This may sound like a silly question, but, do you have an XE head or an XF??? The plugs at the top of the picture look like XF plugs. The bottom row look like XD/XE plugs. I ran XF plugs in my XE once and they were TERRIBLE! The car had no grunt and idled badly. I ripped them out and gave them to a mate for his XF. The good old BP6ES worked fine! The XF plug has a longer centre electrode. I assume the plugs are 'sort of' 'matched' to the combustion chamber design.

 

[xctasy]

As far as intake after the Tb, execute, do u mean that even if i had a flat plate around the TB so that the air wasnt rushing in from the sides and around the end of the TB then going in as in a "U direction it would flow a fair bit more??? Not sure if that makes sense
Like i mean AIR thats flowing along the out side of the throtle body hitting air thats flowing directly into the tb.... So either a flat surface around the front of the TB or a big Belmouth type set up ??

Placing a flat plate a short distance from a smooth bell mouth and allowing the air to flow in from the sides in a smooth, less turbulent fashion will certainly work.

It does so for Weber and SU carbs where space is at a premium. Air flow co-efficents into carbs and EFI throttle bodies are improved if the air flow is less turbulent.

Intake air is unstable, and doesn't behave in a strictly 'logical' manner. Air craft technicians found out years ago that logic is finding out how the air behaves under real operating conditions. Vizard and others have affirmed that suble gentle radius bends and air flow management increases power in restricted conditons. In an example. Valves create bow waves of pressure back up the intake port, and for years, short turn radius work has allowed for the log jam by increasing the runner volume above the hump in the intake port. Same thing happens with a throttle body.

Ford before 1994 found that the subsequent EF's onwards were going have restricted bonnets. So they use special intake ruhners incorporating a resonator box on all versions. Both types of 'torque optimised' intake runners were an attempt to allow the air flow to run as smooth as possible without becoeming tuburlent. The latests BA mk II still uses this design.

In your case, the air intake is pretty restricted by the fire wall and the area around the ledge where the heater box was. You'd be better off organising an small TPI 350 Chev type K and N filter, but don't be affraid of running the air cleaner close to the throttle body. Air flow around the edges will be sufficent for the 600 cfm or so you need.

Gorsh I waffle.

Check ignition first. Wagon and a7m are onto it.

If that doesn't help, then don't be affraid to having a basic air cleaner near that throttle body. The U-tube isn't helping you.

Another option. Look at the VN Commodore EFI 3800. Designed for FWD Buicks, but Holden just put a bend in the intake ram from a rear mounted throttl;e body. At the very least, add one of them with the better K&N intake pod would work well.