Looks like i will be using ITBs on a blown motor im building.

Little worried about getting a reliable map reading as the way i see it, at part throttle on one cylinder it will see boost (valves closed) and on another it will see vacuum (asusming less air from boost past that part open throttle than the engine is consuming in vacuum on that cylinder)

So whats the best way to do it?

Im guessing on just using a balance pipe running beteen the 4 ITBs?

How do liners do it when they are getting a MAP reading?

 

surely you'd still have one plenum though?

run the map off the plenum and it will operate the same surely?

 

No because the plenum (which yes you are right i have a single one) is BEFORE the throttle plates, which means the pressure in there isnt the same as the pressure in the manifold as you get a pressure difference after the butterfly when its only partially open, what you say would be fine on WOT though.

 

for a vauxhall engine chip ? if so you can get inlet manifold with injector ports but with no butterflies ,bolt on ya plenum and one fat throttle valve at the mouth of ya plenum job's a good un

 

Chip,
In this scenario, ecu's use a combination of MAP and TPS to estimate the fuel
demand during throttle closed/vacuum conditions.
Generally TPS is used ONLY for load calculation at say below 10% TPS and between
10% and 25%, a combination of 50/50 is used.
Above 25% then only map is used.
These figures are estimates as it WILL vary depending on engine design.

 

how did they do it on one of the random powered jap motors?

 

lee, yeah i may be able to do it that way i guess, and just use a single throttle before the plenum, would have prefered this way though, if only cause ive got a spare set of bodies lieing around that fit perfectly!

SECS, hmm, not sure how i could set DTA up to do that, you have to either pick TPS vs RPM with MAP as just an adjustment or vice versa, you cant do half and half as far as i know.



Anyone else got any useful input?


will my theory with balancing MAP out using a balance bar not work for any reason, if so why?

 

The Pulsar GTi-R has quad tb's and runs a hot wire MAF sensor rather than a MAP.

 

ive run a map sensor on the quad throttle bodies(on a gtir) and its no problem u just rig the pipes from each port together and take a signal from that

 

Like has been said above...

Guesstimate (map/TPS).

Switch to a hotwire/hotfilm air mass meter.

Or run a vac plenum chamber.... inter connect all the TBs to a common closed chamber and take the map reading from there.

Alex

 

Like SECS says, a combination of MAP and TPS.
A management system like the new Gotech on my Escort can run like this.

 

i'm sure if you really wanted to you could drill and tap a hole after the butterfly ,maybe even all four and connect the four together pipe wise and then to your map sensor

 

Chip use a balance pipe between the 4 TB's then a single pipe to a mapsensor,
This is how the GTR's work I have just mapped 1 with 1680cc Injectors with Autronic's Throttle/pressure mapping, Main fuel table TPS up to 100% then Boost pressure, Ignition table is map/pressure based,
I mapped this in 9 presses of the Accle to 2.2bar boost this system works floorless

Mark

 

do tell

(and no DONT say "buy the mag and see" )

 

just as i said then

 

i so wish you mapped dta god of mapping

 

leecavturbo, The GTR also has a small plenum also just to stop the pulsing but this doesnt stop the vastly diff flow when the throttle is opened and closed, the Ecu will need its own style comp table/mutli maps for this.

Thanks Mark

 

leecavturbo, If you brought Autronic you wouldnt be wishing that

Mark

 

Or maybe if you BOUGHT it, that would work too

 

^NUTTER^,
just noticed your location , i saw/heard you going up the A5 near brownhills @ about 6pm the other night ( donnington visiting ? ) looks/sounds good

 

Autronic doesnt need mapping on the fuel side, it does it itself. Get to Stu lee, he can map anything.

 

Best it's ever been at the moment

Cheers for the comments

 

bit contraversial me thinks, but yeah hav concidered stu @ msd

 

Use a MAF sensor, read the airflow entering the turbo, and have a clever ECU on the other side?

 

Another question. What are the expected gains over a good sized single throttle and decent inlet manifold/plenum ??

Is it enough to make it worth the hassle ?

 

speed density throttle angle, with a balnce chamber

 

well i think i should of read everyones replys and im a little slow

 

1680cc

 

I can only speak for GTRs but the the std 6 throttles/plenum are supposed to give better response/torque than one large single butterfly/plenum but for ultimate top end power the single has benefits.

Cam

 

Mark, thanks for that, much appreciated, looks like i was thinking along the right lines.

re: amm
I dont like airflow meters (or air mass), would prefer not to use one if i dont have to.

re: hassle
Its not any hassle ive got them sat here complete with a manifold and plenum all made up ready to bolt on, so providing i can get a half decent map sorted its not an issue.


cheers everyone for your input

 

This was how I did it on my old mini.

Basically a small chamber where all 4 inlets go to.
vac signal was around -14hgmm to -15hgmm and the idle was a bit awkward to be keep balanced but I think that may have been more down to the throttle linkage. After that I made a single throttle plenum/inlet and vac was closer to -22hgmm and idle was much better to control.



Also I am pretty sure the gti-r has a chamber where all 4 vac pipes go to situated under the the manifold.

Regards muppet.

 

and I said 1st

 

A turbocharged redtop Mini ???? I'm guessing thats pretty quick !!!!!!

 

which is exactly what me and chip were saying 2 weeks ago

i guess he just wanted some different opions

 

I run ITB's on my bike and plumbed all four vacuum lines together (taken from the engine side of the throttle plates) and use a small restrictor jet in the single line that goes to my Map sensor. My MegaSquirt ECU uses revs and manifold pressure to calculate fuel and only uses TPS for Accel enrichment.

Mark