4ag quads

[frost]

strx7. i'm totally interested in what your saying.

so would it be worth the trouble to bore out the blacktop 45mm to 50mm like toda do for Honda engines? for a 1.6 blacktop engine that is.

I've seen them on the 3sge for racing and from what i read they don't bore them out even tho its now on a 2.liter engine.
does that mean 45mm is too big for 1.6 and just right for 1.8 - 2.0ltr

i dont know much about cfm and that sort of stuff. i understand the basic concept but thats about it.

[TRD Man]

Back in the days of carbies, to make a hearty 2 litre rev to 8000-8500 a pair of 48mm side draft carbies were the go,

That's true enough but by & large, whilst the engine would rev highly, it was all top end power.
Good results were achieved with 45's on a 2 litre. 40's were considered more than adequate for a 1600.

It's interesting to note that TRD ITBs for Beams Altezza 3SGE are nothing more than black top 45mm ITBs.

If I were building a 1600 I'd be using the silvertop 43mm with as longer trumpets as I could find, & fit (like the TOM'S items if you can find some).

If you're building 2L, send a pm to RA45. He makes a range of ITB's in different sizes, has tested and raced extensively with them and would be the most knowledgeable in this area on this forum.

[frost]

quote trdman "It's interesting to note that TRD ITBs for Beams Altezza 3SGE are nothing more than black top 45mm ITBs"

yea thats the one i was reading about they just used them like stock even tho they are going on a larger cc engine. really interesting it was like they where made for them in the first place and not the 20valve engines.

i remember someone on this forum saying the blacktop quads are too big for a 1.6 and suffer low velocity speed.

but if they are good for 2.0ltr then why do toyota stick them on a 1.6 (i know in part toy wanted to win n2 and thats why they have quads and 20v)

also why do toda bore them out to 50 for b18c and not for 2.0. its getting mixed up about what size is good for what engine. 1.6 1.8 2.0

keep this thread going its got some good reading

[big_boy]

like has been sed before size is not the only thing that matters i know of a few 1600cc cars in dunedin running 50mm quads but they run them with a longer (gess you call that a plenum) well there further away from the head than normal they loose a bit of bottom end but have extra in the top you need to look at were you want the power high low or mid then you can design sizes & lengths to sute

[Caveman]

quote trdman "It's interesting to note that TRD ITBs for Beams Altezza 3SGE are nothing more than black top 45mm ITBs"

yea thats the one i was reading about they just used them like stock even tho they are going on a larger cc engine. really interesting it was like they where made for them in the first place and not the 20valve engines.

i remember someone on this forum saying the blacktop quads are too big for a 1.6 and suffer low velocity speed.

but if they are good for 2.0ltr then why do toyota stick them on a 1.6 (i know in part toy wanted to win n2 and thats why they have quads and 20v)

also why do toda bore them out to 50 for b18c and not for 2.0. its getting mixed up about what size is good for what engine. 1.6 1.8 2.0

keep this thread going its got some good reading

I guess it would depend on your power curve, maximum power or good drivable torque range.

and strx7 in terms of quoting romanV, I think hes refering to the effective pressure drop between the itb's when at 5% openinig, and the ecu calcuating fuel for the pressure drop (and flow rate) of a single tb at 5% opening. I can only predict it would run lean and cause problems unless the ECU was fooled in some way.

Area wise the itbs are much larger than a single tb. you only have to do the maths: pi * radius(single tb) ^2 < 4(pi * radius(1 X itb) ^2)

[Caveman]

Oh and it should be noted itbs at full noise are music to my ears

[strx7]

and strx7 in terms of quoting romanV, I think hes refering to the effective pressure drop between the itb's when at 5% openinig, and the ecu calcuating fuel for the pressure drop (and flow rate) of a single tb at 5% opening. I can only predict it would run lean and cause problems unless the ECU was fooled in some way.

Area wise the itbs are much larger than a single tb. you only have to do the maths: pi * radius(single tb) ^2 < 4(pi * radius(1 X itb) ^2)

but that is exactly what i'm talking about, the 'effective true diameter' of inlet air tract at the port face or within x mm of the port face (which in effect is what ITB's are) needs to be considerably larger than the 'effective true diameter' of a air inlet - namely a throttle body, at the opening to the plenum chamber as per a single TB type manifold set up.

for instance if you take a 60mm throttle body (common on most 2L turbo engines) which has a sectional area of 28.27 cm2, where as if you divided that up to be 4 TB's of the same area, each TB would only be 30mm diameter, and I'm sure if you ran 4 30mm ITB's on a 2 litre engine it'd be struggling to inhale much past 4000-5000rpm, which would be fine if you had a dinosaur ages pushrod motor which reldined at 4500rpm. But on something cammed and built to pull 8000 they'd be next to useless.

[strx7]

double post

[screamin']

...Bit of an old thread, but damn good read.
I'm embarking on a 6 cyl itb setup using the silvertop quads (1 & 1/2 of them) The motor is only a 2ltr 6, but will have cam and head work and is being built for race use, so low speed drivablity isn't an issue, neither is fuel eco.
I have a feeling the itb's may be slightly over kill as far as cfm goes, but I figure if I can match the cams and head for the itb's I should be right. It's more a matter of doing itb's for the sake of doing itb's! I do hope to gain a bit more throttle response tho.
My question is ecu's. Link G3 reading the tps will do the trick? Are there other ecu's out there I should consider? And what points have I missed, I'm not overly familar with the Toyota throttles, is there anything specific with them that I should know about?

[Burning Angel]

the good thing with the G3 ecus is thay can do 4d mapping.

A friend of mine(Lunchie) has a silver top with 1 and its set up running TPS with MAP compentsation. It idles great without the ISC even hooked up.
the MAP trims the fuel it seems in the midrange rev/load area in the fuel map.

his was the first itb 4age to be run on the G3 ecus as i installed just as they were released. was tuned by Mike Lyn at turbo shop who did an excellent job

[QikStarlie]

yeh the 4d mapping on the g3's works mint with quads. my smallport with 20v quads runs one

[spencer]

if your game a megasquirt with appropriate code will do tps and map

[jondee86]

As it stands, this is pretty much a meaningless statement

for instance if you take a 60mm throttle body (common on most 2L turbo engines) which has a sectional area of 28.27 cm2, where as if you divided that up to be 4 TB's of the same area, each TB would only be 30mm diameter, and I'm sure if you ran 4 30mm ITB's on a 2 litre engine it'd be struggling to inhale much past 4000-5000rpm, which would be fine if you had a dinosaur ages pushrod motor which reldined at 4500rpm. But on something cammed and built to pull 8000 they'd be next to useless.

Correct me if I'm wrong, but a four cylinder four stroke engine will have
four consecutive intake strokes. So the volume of air being drawn into
each cylinder of a 1600cc engine would be 400cc per intake stroke
(180 deg of crank rotation). For the other 540 deg of crank rotation, the
inlet valve will be shut = no sucky. And for the moment I shall ignore
the effects of cam overlap, VE, polar inertia, OOS, solar radiation and
colonic irrigation

Therefore flow through a single throttle body into a plenum is 400cc per
180 deg of crank rotation, the same as the flow through a single ITB.
The difference is that the flow into the plenum is continuous, whereas
the ITB is only sucking once every 720 deg of crank rotation. So why
not use a single 45 dia throttle on the plenum ??

For the best inlet flow, the air velocity should increase gradually as it
passes along the inlet tract, reaching maximum at the inlet port on the
head. Sudden changes in cross sectional area of the inlet tract are to
be avoided. So, taking your 75 dia air intake, squeezing it down to
45 dia, and then expanding into the plenum would be bad, creating a
restriction. Better to use a larger throttle and increase the velocity step
by step.

So, as I see it, any attempt to compare the effectiveness of 4 x 30 dia
ITB's with a single 60 dia throttle on the basis of cross sectional area
is.... well... meaningless

Cheers... jondee86

[screamin']

So a G3 or Megasquirt would still have the same functionallity on 1 & 1/2 silver top quads, right?
Now under the injector loom (haven't got it infront of me so doing this off the top of my head) there is a plate the length of the itb, that is screwed on. It appears it would have a cavity behind it, is this a chamber for vacuum for something? If I'm splicing two itb's together do I have to link these chambers?

[AceSniper]

the chamber is used for, ICS TB bypass, a/c idle up, pcv valve vacume and another pipe

[QikStarlie]

thats on the manifold itself tho, not on the actual throttle bodies. its uneeded on a custom setup. it wont worry the ecu how many cylinders

[screamin']

Sweet, cheers guys. I'll be sure to let you know how the Nissan - Toyota mateing goes.