ITBs

[dickie]

Hi Folks,
Thanks for the comments.
When the car went to the rolling road it had the ECU map sensor hooked up to a manifold block, at the time I did not realise that on NA tune the MAP table should be set to 100 ( This is the set up bit that the tuner missed )
I have now adjusted the tables and the sensor now reads atmospheric not manifold pressure.
I will have a look into overun fuel cut if my changing of the cells does not work out.
The area I have changed does not appear to be used under load, it is along the 0 percent throttle opening line between 4000 and 6000 rpm.

I also think for ITB use the mapping have a lot more definition between 0 and 5 percent throttle. ( I will contact Motorsport electronics about this )
At the moment the tables are set at 0/2/5 percent.
I think .5/1/2/3 would give better definition at small throttle openings. ( This is a road car / competition car )

[dickie]

fuel consuption is epic. 125 miles to a tankfull.
Car still needs more mapping work as it running rich a lot.

[dickie]

I have just ordered some windscreen washer non return valves to fit in the vacuum lines going to the block in the hope of getting a better signal for the ECU
I have binned the idle control valve as it was upsetting the vacuum signal too much, the car seems to be fine without it.

[noobie]

Have you guys seen this:
github.com/jharvey/MultiMAP

Its a circuit designed to run individual cylinder/runner map sensors. So instead of first damping and averaging the map signal (by way of a vacuum block), you can sample each runner individually and have the board return the max vacuum over all cylinders at all instants. That should massively boost the vacuum signal the ecu has to work with. Potentially enough to run speed-density. Would be way less temperamental then any TPS based tuned.

[atlex]

interesting. I wonder what the latency is like.

[dickie]

I am also planning another air box with the inlet in a better position, the first version has the inlet too much blanked by the inlet trumpet.
Having made one I can now work out how to make a better one to fit the PX500 backing plate.
I am also looking at using a more modern MAF with the airbox ducting.

[warpspeed]

Nov 4, 2020 22:32:12 GMT atlex said:

interesting. I wonder what the latency is like.

There will not be any latency, that is the whole point.

Using a secondary mixing manifold after the throttles to average the pressure pneumatically, involves filling and emptying a certain manifold volume. The greater the volume, the better the averaging, but a step change in throttle position will involve some small latency while the pressure settles to its new value.

This will also be upset by bleeding air into the mixing manifold from the brake booster, idle speed control,  PCV, or from other systems that require vacuum to operate.

If you do it electronically with an individual MAP sensor in each runner (after each throttle), the four instantaneous pressure readings can be added together to create a pressure average electronically.  Its virtually instantaneous, no filling and emptying involved.

This has certainly proved to be a workable system, but unless you have the electronic expertise to add it to a commercial engine management system yourself, it may be difficult finding someone that can do it for you. I am an electronic engineer, so its something I plan to look into myself later on, with my own planned ITB setup.

The other way to approach the whole ITB issue that is known to work, is to have two separate systems. 

Use a MAP sensor and averaging manifold to control the usual speed density system which operates most of the time in the normal way. 

Also set up and map a complete alpha N system that uses only throttle opening angle and rpm.

Its then possible to blend the two systems in software using yet another map to get the best possible overall result.

The alpa N system works quite well at small throttle openings where vacuum is very erratic and really unusable, but because it only relies on throttle angle and rpm, it cannot correct for changes in temperature, or barometric pressure. So its less than ideal for an every day road car.

Speed density is a far better system for the road, that can correct very nicely for everything, but it relies totally on a reliable MAP pressure reading which is very difficult to do at really small throttle openings and ITB, where there is very severe pulsing.

[dickie]

Hi Folks,
I have been learning a bit more with the ME221.
It can adjust the map depending on IAT and engine temp.
I have got the Long Term Trim doing its stuff and the Map is improving, I have still got a few lean spikes but I am hunting them down with Megalog Viewer and the ME 221s logging feature.
I am getting the chance to crack the throttles open a bit more as the tune is coming together. ( Running with the PX500 foam filter at the moment )

[dadbif]

This is the airbox I used on my carb setup with an AFM

[dickie]

Hi Folks,

The parts for the new airbox arrived from Merlin Motorsport today.
A New ITG filter itgairfilters.com/product/arab54-airbox-arab54/ rated up to 200 Bhp and an alloy hose bend to go into the plenum chamber.
A set of EV14 550cc injectors have been added to the mix, I am running them at 70 psi and so far I have managed to improve the tickover.
The car will have to be re mapped at some point to take in the new induction system and removal of the air manifold linking the ITBs and vacuum feed to the fuel pressure regulator.
I noticed that the pressure dropped when the throttle was cracked open with the vac in place.
Roll on the spring when the car comes off Sorn.

[dickie]

More ITB Ramblings.
It appears that BBR GTI have finally got the ITB sets for the 1800 engines ready to launch to the world !
They should be on the website at the weekend.
I have been interested in these since seeing them a few years ago.
I think I know what I will be getting myself for Christmas !!! If I can wait that long!!!

[dickie]

Hi Folks,
I have just ordered a set of BBR ITBs for a Mk2 1800 as I am running a Mk2 head.
So looking forward to the installation !!!
Christmas has come early !!!
They are available to view on the BBR GTI website and facebook page.

bbrgti.com/collections/mazda-mx-5-na?filter.v.price.gte=&filter.v.price.lte=&filter.p.product_type=Intake&sort_by=best-selling

Cheers Dickie

[dickie]

Hi Folks,
I have just ordered a Hondata phenolic inlet gasket to go with the ITBs.

[Zed.]

Sept 17, 2022 15:31:05 GMT dickie said:

Hi Folks,
I have just ordered a Hondata phenolic inlet gasket to go with the ITBs.

do they actually do anything?

^^ From previous conversations with engine-builders

Rich.

[atlex]

Meant to reduce the head-to-manifold heatsoak, other than that they can't do much. and frankly to fully benefit you'd probably also want some heat-isolating washers on the nuts/bolts attaching the manifold to the head.

But the heatsoak in the engine bay is massive anyway if there's no airflow. doesn't air flow faster over a hot surface ?

I've got a hondata phenolic gasket for the k20 in the mr2 to go on too. When it goes on I'll do some comparison type runs, when it gets hot again. I've got lots of run data from hot days this year.