q45 TB conversion help reqd

[elliotaw]

I have considered a twin throttle body setup, but I'd rather stick with a single just as I prefer the less complicated look. I understand that the Q45 TB is amongst the largest available at 90mm. I know very little on how the electronic functions of these things work so need to do a little homework.
I am thinking of doing a little cut and shut on a standard 1uz plenum to mate upto the new TB.


What I dont know is :-
how compatible are the TPS ? is it just a case of swapping the leads ?
If use a Q45 MAF sensor, is that a direct swap also?
What other factors might be affected by doing this swap ?

Help, anyone ?

Elliot

 

[Lextreme II]

I think there are three major modifications require:

1. Engine Cable System
2. TPS (It only has one, most Lexus have two)
3. Mounting pattern to Lexus intake.

This might not a problem but should also consider would be clearance to the fuel rail. Its an interesting modification. If this can be accomplish, how much gain do u think this will give?

 

[elliotaw]

I've gone down the route of a lot of people on here as far as engine mods go....bigger valves, flowed heads, bigger cams etc. I think the next weakest link is going to be the TB opening.
As fas as the mounting pattern goes, I would completely cut and shut the plenum to allow a 90mm full flow. This would mean removing the side section where the normal lexus TB mounts and welding in a new section of aluminium tube and flange. Thats probably the hardest part to do nicely but probabaly the part I can have a good go at.
It's the other factors I need to address that you mention.

How do the TPS differ and the cable system. Is the Q45 similar in that it runs the cable that runs down to the transmission ?

I am planning on running a link engine management system eventually so should be able to run a 'map' from a q45 also and retain the larger sized intake right through. Is this the right way to go ?

Elliot

 

[Peewee]

I am planning on running a link engine management system eventually so should be able to run a 'map' from a q45 also and retain the larger sized intake right through.

I'd change that 'eventually' to 'right away'

Get the stand alone now, and you can run any TPS you like.
Link, like all, will come with its own MAP sensor, so you don't use the Q45 one.


As soon as you change any of the major air characteristics of the motor, the stock ecu will not be able to compensate properly.

 

[Pro]

Peewee's right as usual - a standalone will be A LOT less headache in the short and long term.

you'll spend just as much recalibrating the stock computer with a day's dyno work as you will on a standalone system and 2 hours dyno.

make the switch "right away".

 

[elliotaw]

I wish it was all so easy, but my engineer will not allow me to run an aftermarket computer so I'm stuck with the original one until he signes the paperwork that the car is fit for the road.

Elliot

 

[JDMfantasy]

does anyone have a cad layout for the q45 tb holes, or happen to know them off hand, I thought they were 80mm square? anyone know?

 

[elliotaw]

Not actually had one in my hands to measure yet. but looking at some of the pictures of them on ebay. Being that the port is 90mm in diameter, you can guestimate the positions of the 4 mounting holes. I'd say they would be closer to 90mm apart ??

Elliot

 

[cowboy bebop]

The outside distance bolthead to bolthead is 90.00mm. The inside distance bolthead to bolthead is 66.67mm. The math says the bolt hole distance center to center is 78.335mm. But don't take it as gospel as it'd be better to take the measurment first hand.

Eric