trottle body

R

Robert Whelan

I was woundering has anyone tried to bore out the standard micra trottle body to a bigger size with a new butterfly, if so what are the problem faced with

As running the 1.6 one seems to give more problems than power, where a bigger micra one you might see better results?
 
Ye what ever butterfly i can find to fit really. i can do all the work myself have access to all the machiney you would need.

What size is the standard body and what size is the 1.6, as i have a 55mm butterflt in work that i could have a look at.

If it works for me i could do a batch for everyone and would solve the problem of trottle body for the micra's
 
robert

cg,s are 45mm, and ga 1.6 are 50mm, 20 something% increase iirc.
they,ve got the same 2 bolt fitting as far as i can see
 
You get a 11% increase with a ga16 trottle body

With a 55mm one you will get a increase of 44% over standard

If you have a spare 1.6 butterfly i'll take it off you and fit it into my trottle body, or better would be if i could get hold of a 1.6 ga body as i would need to take some measurements from it tbh

I can have a look at the 55mm one tomorrow i'll get my body off and see what i can do.

the reason i say this is that the ecu will think it's on standard body but it will be flowing 11% or 44% more air there for should be able to run right unlike some of the 1.6 trottle body ones i have one on at one stage didn't idle right and overfueled down low.

By the way frank do you know where i can get a 1.6 airbox from?
 
Robert Whelan said:
You get a 11% increase with a ga16 trottle body

With a 55mm one you will get a increase of 44% over standard

If you have a spare 1.6 butterfly i'll take it off you and fit it into my trottle body, or better would be if i could get hold of a 1.6 ga body as i would need to take some measurements from it tbh

I can have a look at the 55mm one tomorrow i'll get my body off and see what i can do.

the reason i say this is that the ecu will think it's on standard body but it will be flowing 11% or 44% more air there for should be able to run right unlike some of the 1.6 trottle body ones i have one on at one stage didn't idle right and overfueled down low.

By the way frank do you know where i can get a 1.6 airbox from?
Click to expand...

nah, 11% bigger diameter, but 20 odd bigger surface area surely ?
it,s gonna throw the a/f/r,s out tho eh, mine has big gains on gas, but on petrol the 5th injector is very crude, and i hav,nt refined it on petrol yet
 
Flow rate wise i could work it out but couldn't be bothered really as you get figures but the inlet pulses can either help flow more or bounch back more air depends on how good the manifold is.

I see what i can do as i'm takin the head off my 1.0l skimming it, equalising combustion chambers, port and polishing head and manifold, fitting 1.3 cams, fitting janspeed manifold but leaving the decat on for the mo.
But to see some gains i need to flow more air in but might try a back to back with a standard trottle body and a modded one and see how they feel.
I'll up the fuel pressure a tiny bit but don't have a lamda sensor on the car and it's not worth the hassel putting one in. but if i need to i could put my motec one on for a weekend
 
robert

think of it as, 2x 10mm balls in a 20mm ring, there,s loads of space around the balls, so a 20mm hole will flow more than twice (probably nearer 4x) that of a 10mm one
an autosprint inlet cam, 1.3 exhaust cam, 1.5mm skim, 2nd decat and a lightened f/w ftw
 
Do you know what cam timing the micra's run?

I build engine as my day job so easy enough for me to do.

Ye i hear what your saying but it doesn't work that way on engine due to inlet pulses and a lot other thing like air density and so on.

a 1.5mm skim is hugh have you ever measured you piston to valve clearance after you did this. I would
 
robert

i dunno, usually 110deg is,nt it ?, i found the car more drivable with plenty of advance (especially the inlet cam, which is quite wild), but thats probably mainly due to chain stretch (80000mls)
 
110 deg is quite adv more for drivability and torque

I'll probably retard my inlet and exhaust. Will put the power higher up the rev range with this. Also the more you retard the timing the more your piston to valve clearance closes up. So it's a balancing act, that why they put cut outs in the 1.3 pistons.
 
Robert Whelan said:
110 deg is quite adv more for drivability and torque

I'll probably retard my inlet and exhaust. Will put the power higher up the rev range with this. Also the more you retard the timing the more your piston to valve clearance closes up. So it's a balancing act, that why they put cut outs in the 1.3 pistons.
Click to expand...

robert

i,ve never seen cutouts in cg pistons fwn
 
ye i race formula fords for the last two years in the northwest championship, but not this year due to work so rebuilding the car ready for testing next year.

Just google my name with formula ford after, a few articules and stuff comes up, which you can have a look at if you want.

I presum you are all going to be asking for tires now, but no i use the used ones for testing and wear them down to the small blocks in the centre of the tire and then there no use

Where are you in birmingham?
 

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