CG10DE Thottle Bodies (Trumpet Length?)

Revmau5

Revmau5

This is the opening post for my throttle bodies conversion. I had wanted to post with it all finished but i need some assistance before i conclude - sadly. :(

My Problem

I've been looking at trumpet length, i know i mentioned it in a previous post - but i'm struggling! I've been using different resources, eg:

http://www.emeraldm3d.com/articles/emr-adj-length-intake/
http://www.s-86.com/s-intake.html (...although VVTi based)
http://www.jenvey.co.uk/jenvey/throttle-body-selection-with-jenvey-dynamics

...just for some references!

I know it totally depends on the car, and what you're after. I'll mention that i'm not racing this thing, but i do want power gains in usuable areas at the upper range. I'm just finding it contradictory...

David Walker mentions that he uses 170mm trumpets and shorter in his testing and has good gains (for what i'm after) around those upper lengths...

However, Jenvey say that 9000RPM =350mm and proportionately 18,000RPM = 175mm. I mean, that's double one half the other, so does that mean for 4500 = 700mm?!...and if so, i work out that 6000 is approx 500mm!?

...and if David Walker claims that 4mm is enough to move the range....!!?????

aljkdklasjklhassfQKQCXCX....sorry, my brain went into a severe panic there. Can some please guide me on the path?!

Results so far...

On a side note, i've only bodged together this whole thing for testing, load of cable ties and some duct tape holding together a plenum (for MAF etc).

I will say that the first setup run I had only about 200mm length. This gave severe power loss and would top out at 45 in 2nd. (...as reference.)

Secondly, I moved the plenum in front of the engine...it's about 650mm say? I was well over 60mph in second and got scared. I actually had to check i wasn't in 3rd, but it was revving it's little head off. Problem is it takes too long to get there!

Please help, advice needed!!
 
is this for the length of the inlet runners revmau5 ? or bellmouth trumpets ?
and your powerband will hit a brick wall @ about 6k with 1.0 cams eh :eek:
 
He'll be meaning the overall intake tract length Frank, measured from the back of the valve to the intake bellmouth face.
 
Low Rider said:
He'll be meaning the overall intake tract length Frank, measured from the back of the valve to the intake bellmouth face.
Click to expand...
ahh :)
well length tuning on a 4 stroke road car is pretty pointless imo, and the dia probably has more effect.
the factories usually design a long thin bunch of banana manifold nowadays eh, just for low-down drivability
 
Fair point but like I said, I've physically driven mine with long and short inlets and it's like 2 different cars. I don't have the luxury of diameter tuning, for one it's a backyard job more for testing - and so don't have access to any method of trumpet construction that i can think of. (Ideas welcome!) Not to mention the confined space. I'm using GPz throttle bodies which are like 32mm iirc.

After a good thrashing tonight I've found plenty of low down torque, like I really mean plenty. I'll maybe just make adjustable lengths and go play on my local dyno some night. Also, 6k is enough for daily driving! Lol.

Also, I don't have any bell mouth trumpets on ATM - more due to size limitations on the plenum.

Also welcoming ideas on how to get rid or the plenum which I need ATM for maf sensor. Anyone bypassed this somehow?

Cheers lads for the replies so far.
 
Just thinking, got to be someone on here running throttle bodies without a common plenum? How do you run these without MAF sensors?
 
Revmau5 said:
Just thinking, got to be someone on here running throttle bodies without a common plenum? How do you run these without MAF sensors?
Click to expand...

I do, so does Paul Smith and chickenwahoo on here. They run TPS load / engine speed with temperature correction, (Alpha-N type) mapping using an aftermarket ecu.
 
Now...in laymans terms? Did i mention that this is a DIY build...i'd prefer avoiding the cost of lol!!

Is that literally it by the way? The TPS load (in volts) / Engine Speed (being read from which sensor?...in volts im guessing SOMEwhere?)
 
Revmau5 said:
Now...in laymans terms? Did i mention that this is a DIY build...i'd prefer avoiding the cost of lol!!

Is that literally it by the way? The TPS load (in volts) / Engine Speed (being read from which sensor?...in volts im guessing SOMEwhere?)
Click to expand...

Cost will be your biggest enemy even with the likes of Megasquirt, so will pretty much kill anything other than making something up to utilize the OEM MAF sensor through a common plenum.
 
Yeah that's what im doing at the minute...

Well...it's a piece of rainwater downspout, with a hole in the end, 4 tubes running in at 90° lol. Is this the only way then?
 
Skinner_87 said:
You could adapt a chamber of a SR20......

http://www.ebay.co.uk/itm/Inlet-Man...arts_Vehicles_CarParts_SM&hash=item3f17bdf3b9
Click to expand...

This is a 4EFTE / CG manifold project in the making ;)

30062010811.jpg

30062010814.jpg
 
Yeah but i'm running ITB's though, that would be no good. Like...i have a set of GPz1100 Throttle Bodies which really need trumpets, i've only got straights on them at the minute, no fluting at all.

I've no idea how to make trumpets for a start, even if i did...i've got the problem of them going into a plenum - so defeating some gains i'd rather have on my side of the fence.

Don't get me wrong, it's running sweet...i just need to tune the intake length. Thing is, i'm doing this all on a Dyno evening this week and so if i had as many problems as possible sorted (or even some theory on how to) i could postpone so i get better results from the session by doing the work beforehand.

...if any of that makes sense lol.
 
What i was thinking was to weld the trumpets into the chamber so you can the have a MAF on the end to take readings from, bascially a metal airbox.. your other benifit is that you then have a vacuum for your brake servo....

Can you not get some trumpets cheap off ebay?

Its an idea i considered for my carb setup.
 
I've used blanking plates to cover the injector holes on the GPz's. I've added a plug to this for my brake servo, works a treat.

Yeah that setup is what i have. The problem is you have to have the plenum at right angles to the inlet. I'd say there would be much better flow if they were end on, direct flow in kind of thing. This would create a plenum of large diameter though, so the MAF doesn't function correctly. The middle link in my first post noteably (http://www.emeraldm3d.com/articles/emr-adj-length-intake/) , says there isn't as much difference in parallel trumpets and tapers as you'd imagine. This is why i think gains would be greater without the plenum, even with straight inlets.

Probably, postage to Northern Ireland is a total hassle though. I'll have to take a nosy. For example, i ordered 2 sets of throttle bodies for my project...still waiting on the other.
 
i agree, if you have a 90deg bend plenum you may as well use a single t/b eh, it needs to be like a 4-2-1 design really :)
 
...and forgive my idiocy - how does that work with stock ECU? I love that though! Where do those elbows go? What MAP do you use?!

...and relax. This is why I love this forum.
 
Hi
Sorry was just illustrating how I got a map take off. I ditched the ecu and use bike carbs and mappable ignition.
As for the individual take off's they go to a chamber which then has a individual outlet which feeds the map sensor.
 
I'll measure the operating range of my MAF tonight, (unless of course you know it Frank lol ;) ).

What do you mean resolution problems?

Well I was looking at a Rover and Peugeot one just googling....both seem to be 3 pin (Signal, +5v, Ground).
 
Revmau5 said:
I'll measure the operating range of my MAF tonight, (unless of course you know it Frank lol ;) ).

What do you mean resolution problems?

Well I was looking at a Rover and Peugeot one just googling....both seem to be 3 pin (Signal, +5v, Ground).
Click to expand...
the ecu runs from tables/multiplyers eh (load x rpm etc) polly has some info on his blog.
and baguete could,nt get a GA t/b to run properly on his nistune, they have different resolutions iirc (sort of an 8 x 8 table trying to fit into a 12 x 10 table kinda thing)
 
Well i'd had in mind a few measurements at different RPM's to see what the output was between the pins....maybe bodge something up with the MAP in place to test it.

You're right it'll never be that simple, but then i said the same thing about throttle bodies! Few cable ties later and some silicone hose, and what do you know!! Haha.
 
there,s a lot of trial and error involved with ghetto modding eh :D
my most useful tool is the (£10) narrowband a/f/r guage, once you get used to how it reacts in realtime, when you alter fuel pressures etc , it can give really useful feedback (even with its narrowband limitations)
 
PS i'm reading Polly's rebuild blog. Jeez. I'd love to say im quickly scrolling to find the info, but i'm in awe at the work he's done!
 
i should be getting hold of a wideband tomorrow Frank, temporarily anyway. final touches to the emerald! :D im going this way too with cbr600 carbs. this thread is full of useful tit-bits!
 

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