Technical Making a 45 mm TB whats the biggest you've seen on a 1108 spi??

[NeilCinq]

Hi All just wondering whats the biggest tb people have seen on a cento 1108 spi.

I'm making a 45 mm one out of a old Toyota twin cam tb.

Its just for the laugh really, but if it works well i will incorporate the idle air controller as well.

 

[Sir16v]

largest ive known of is 40mm tb made by tricker i think it was,standard tb bored out,overs put on larger tbs from puntos going from 32-38,40 are rare as hens teeth now and will be for some time

 

[NeilCinq]

yea ive seen the tricker ones all right there pretty nice bits of kit, been considering making one myself.

but i heard that some people were using 42 and 43 mm ones as well.

then i thought what about 45 mm....

 

[blu73]

IMO it will not work as well as a 40mm, there is such a thing as a TB being too big. But carry on, see how it goes

 

[jonjg]

does changing the tb size mess up the fuel to air ratio making it run lean?just wondering?

 

[blu73]

no the ecu will pick up that there is more air and chuck more fuel in to compensate

 

[NeilCinq]

yea its a bit redonculous alright, but it is just for a laugh.

should be finished it tomorrow eve just the throttle cable bracket to go now.

ill stick up a photo of it when it goes on the car.

should look funny

 

[medion6969]

hmm ive a 40mm tricker on my tuned 1108 but tbh its not much better than my modded p75 38mm TB.
I reckon blu is spot on 45mm will cause it to bog down and run lean,unless u can increase the fuel to match the airflow.
but saying that it will be interesting to see the outcome

 

[Pep0]

tuning is about how you want to use the auto if you are never going to use it other than on fast tracks with no slow bends then it won't go down the high street cept Sunday mornings

do you have a high street auto as well as a track auto?

 

[jatkinson]

Im intested on how this will turn out , May cause some rough running when first fitted , but the ecu should sort that out a little , AS long as the *insert jap car name here* tb has the airflow sensor in the tb Like the Fiat ones do ,,

if the toyotas dont have the air flow in were you going to put it?

 

[blu73]

its worth pointing out here that you are gonna need to modify the inlet manifold too, the hole in top for the TB is only 40mm iirc. Hence why tricker tb's were 40mm

 

[Honeymonster]

no point in having a huge throttle opening. You get to a point where the engine can't inhale anymore without head/cam modifications. You will just get full power before the pedal is fully down and poor throttle control.

 

[NeilCinq]

Tried it on the car today. have to say there is a improvement in performance, just at the top end though.

As expected under 3000 or so it can bog a little when you stamp on the pedal but its manageable. and this tb will only be really used for competition use anyway..

also i'm glad to say the engine is idling fine, its a miracle if you ask me (considering there is no idle air controller) but i'm not complaining.


next task will be to port the manifold out so its 45 mm as well and to make the adapter plates a bit better again to improve airflow.

all in all i'm happy!!

one of the funnier things is i have to push down the corners of the bonnet to put in the bonnet pins as the air-box is hitting the inside of the bonnet. When the bonnet is closed and the engine is revved you can see the bonnet "pulsing" lol.

you can see in the photos I've just left a idle air controller connected to the wiring loom, also you can see that the air box looks a little crooked, that's cause of the way the top part that has the injector had to be mounted.