EFI: larger plenum

[JochemsTR]

deleted

Edited December 7, 2020 by JochemsTR

[john.r.davies]

CK,

One tiny, tiny quibble - the angle of your injectors!

They will spray the opposite wall of the duct, not the throat of the head inlet or the back of the valves.    That angle probably reproduces that in original throttle bodies, but with PI which is only very roughly timed to valve opening, so doesn't matter.     You're using modern injectors that can be pulsed accurately to coincide with valve opening, so not taking advantage of that.

John

[TriumphV8]

23 hours ago, john.r.davies said:

No argument with the statements above, but I'd love to know where they come from/their authority.

TV8 - "the inlet liners the speed should be limited to 80m/sec."

and

trolleybus: "The volume of the plenum should be 85% of the swept volume of the engine"

Can you provide references, please?  Books, papers?

Hi John some of my knowledge is from Apfelbeck/Wege zum..... and H.Hütten/Schnelle Motoren.... and H.Hütten/Motoren.

Would recommend Apfelbeck to everybody who is interested in tuning because he is a guy that does the job with a pretty low machine equipment, that mostly can be arranged at home. Always with the approach as good as possible but also as cheap and easy to reproduce as possible with the help of some good ideas.

[SpitFireSIX]

A long time ago my EFI CP was on a RR with GT in the driving seat. Maynards? Cider drinking region.
They checked OP with & without plenum. No difference. My plenum did not amplify peak power.

[john.r.davies]

Ach, Zo!  Danke, TriumphV8!   Apfelbeck on "Wege zum Hochleistungs-Viertaktmotor: Ein Handbuch f??r Liebhaber und Tuner von Viertakt-Motoren "Paths to the high-performance four-stroke engine: A manual for fans and tuners of four-stroke engines" (Google trans)

But I am ashamed to say that I cannot read, let alone speak, German.      The ability in English of our colleagues abroad should shame us!   There is an opening here for a translator!

If you would like to read an eqivalent text in English, mine is "Four Stroke Performance Tuning" by A.Graham Bell.

John

Edited December 8, 2020 by john.r.davies

[ntc]

On 12/5/2020 at 5:04 AM, JochemsTR said:

I really do not want to overdo it on this topic, but I remain curious. and I am sure I am not the first one experimenting...

Any ideas or thoughts regarding the outcome of installing such a fan in the air intake, so actively forcing air into the plenum?

The fan would be controlled by the TPS Sensor, so no support during Idle, but rather during driving and WOT.

Jochem

 

PS Picture is a sample, ofcourse it runs with 12V

Hi

Yes try a boat engine bay inline fan can do up to 235 cfm worked for me on Webers.

[John Morrison]

A recent post here together with a relevent reply, are way off topic and lets say

could be construed as less than friendly.

I have hidden both, happy to discuss with either party, or the subject in general in Alecs Inn.

John.

[john.r.davies]

Thnak you, John!

[CK's TR6]

John makes a good point about spray pattern. My. Injectors are angled at about 35 degrees and the end of the injector is just outside of the ID of the inlet tube.  Guessing now, but the spray pattern goes across the whole inlet cross section and the end of the spray hits the opposite side about where the manifold hits the head. I do have sequential with the fuel pulse ending at 40 degrees ATDC on the inlet stroke. So the fuel pulse will see the flow during the injection pulse and the junction at the head is a high temp area, being so close to the exhaust, which would aid in the vaporization of any wall wetting. I did find this photo of different spray patterns.  Maybe someone could utilize the first pattern to shoot the fuel pulse right down the intake port.

[john.r.davies]

Learn something every day!    I'd never heard of the gamma angle injector, but apparently they can angle the spray by 5-25 degrees.   Leaving yours 10 from straight down the inlet, CK. 

The split is for dual inlet valves!

 Thanks for the  seminar!

John

Edited December 9, 2020 by john.r.davies

[Rob Waldron]

On 12/5/2020 at 5:04 AM, JochemsTR said:

I really do not want to overdo it on this topic, but I remain curious. and I am sure I am not the first one experimenting...

Any ideas or thoughts regarding the outcome of installing such a fan in the air intake, so actively forcing air into the plenum?

The fan would be controlled by the TPS Sensor, so no support during Idle, but rather during driving and WOT.

Jochem

 

PS Picture is a sample, ofcourse it runs with 12V

I was told that fitting a fan would confuse the metering unit as you could be stationary or slow moving when the fan kicked in. The metering unit would give extra fuel as the air pressure would change ? 

[stuart]

1 hour ago, Rob Waldron said:

I was told that fitting a fan would confuse the metering unit as you could be stationary or slow moving when the fan kicked in. The metering unit would give extra fuel as the air pressure would change ? 

Not on PI as it goes on engine vacuum.EFI with single body might well be different.

Stuart.

[john.r.davies]

2 hours ago, Rob Waldron said:

I was told that fitting a fan would confuse the metering unit as you could be stationary or slow moving when the fan kicked in. The metering unit would give extra fuel as the air pressure would change ? 

Wot?   Like this?

  As sold on  eBay!

I think that electric "turbo" fans are considered to be complete borrocks.   A little fan like that might cool your overclocked games PC, but do nothing for an engine.

John

[CK's TR6]

I have been looking at e superchargers lately. First issue is where to mount the 2 (48V) LiFePo batteries without changing the height or longitudinal position of the CG.  The upside for me would be improved torque below 3000 RPM. Keep in mind that my first dyno run 14 yrs ago was 152 HP and 175 lbft at the rear wheel.  It’s that below 2500 RPM I dont quite keep up with supercharged cars. Also, when operating at elevations between 5000’ to 9000’ my NA car loses quite a bit of performance. 
 

https://torqamp.com/product-category/electric-supercharger/

[Steve-B]

Fascinating topic to me, I keep learning more and have a question

My car came with a box o'bits - 1 of which is the original Triumph plenum tube, sans rubber connecting tubes + intake tube to rad grille. I'm guessing it was the PO who restored my car didn't reinstall it and instead used 3 K&N oval air filters. I recall from Caterham ownership there was a bit more power gained by having separate filters on each one(which also raised intake/throttle sound), so my question is there any reason to back to the plenum tube? Or, should I just keep it for those years from now when I sell it onto the next keeper as an original part?

 

[TR NIALL]

19 hours ago, Steve-B said:

Fascinating topic to me, I keep learning more and have a question

My car came with a box o'bits - 1 of which is the original Triumph plenum tube, sans rubber connecting tubes + intake tube to rad grille. I'm guessing it was the PO who restored my car didn't reinstall it and instead used 3 K&N oval air filters. I recall from Caterham ownership there was a bit more power gained by having separate filters on each one(which also raised intake/throttle sound), so my question is there any reason to back to the plenum tube? Or, should I just keep it for those years from now when I sell it onto the next keeper as an original part?

 

My choice would be Plenum Tube all day long,it’s cold fresh air that is required and you can’t achieve that with 3 K&Ns sitting above a hot Manifold and hot air passing through the Rad.

[Steve-B]

3 hours ago, TR NIALL said:

My choice would be Plenum Tube all day long,it’s cold fresh air that is required and you can’t achieve that with 3 K&Ns sitting above a hot Manifold and hot air passing through the Rad.

That's what I thought someone might say as it has always seemed weird Triumph put in / out on same side. Major heat no-no I would've thought. Visiting Chilterns valley events I've seen far more plenum tubes than not unless that car is on Carbs and not fuel injected...

[Andy Moltu]

It may or not be relevant to efi but one of the reasons people assume cylinders 5 & 6 are running rich is that they examine the plugs when the car has been ticking over or running at minimal throttle as you park up.

Ideally you should do a plug chop - when the car is warmed up and you are driving at a decent speed, dip the clutch and switch off the engine and coast into a lay by or somewhere safe to check your plugs. Otherwise what you are doing is assessing the impact of running on closed throttles where the air intake is coming through the air inlest valve (or idle control valve in the case of efi) which on the TR6 is at the front of the front inlet manifold/throttle body so No1 inlet get first dibs on the incoming air and 5 & 6 are the most distant from the air inlet. By the time it gets to the rear manifold the pressure may well be lower and the air warmer. So running rich on 5 & 6  at tick over is not necessarily indicative of running rich when driving.

A bigger plenum may help airflow at revs with a wide open throttle but you still may soot up 5 & 6 when ticking over to the same extent.

The other thing to bear in mind is that most efi conversions on cars like ours are of "wasted spark" functionality - a crank sensor to to accurately control timing but the system ignores whether the engine is on firing or exhaust stroke. Firing a spark at exhaust gasses does nothing harmful. In terms of how the injectors are timed is not considered critical so long as the volume of fuel injected is correct relative to to throttle position, manifold pressure air and engine temp, lambda etc.

Modern cars tend to have cam sensors to identify whether it's an inlet or exhaust stroke and time the fuel pulse accordingly. This isn't such an easy retro fit - I suppose the dizzy drive mechanism could be used but play and the relatively small benefits of doing so to enable more precise timing of the fuel delivery on old engines are not reported as being significant enough to justify.

[CK's TR6]

When I first conceived my EFI intake, I was concerned that cyl 5/6 would breathe differently. I had batch fuel on 6,5,4 and 3,2,1.  My plenum is quite large and each runner is belled internally. So, I put a wideband O2 on the front 3 and another on the back 3. I did extensive logging on the engine. The O2 readings stayed within 0.5 AFR of each all the time except one case. That was when the throttle was fully closed and the RPM was above 3000 RPM, ie during a shift.  Keep in mind that the MAP at this specific operating point was approximately 12-15 KPa.