Individual Throttle Body tech

[Mike-e]

thread almost makes me want my motec back

[Spencer]

^ hard, I'd be so stoked to own a decent Motec.

You pretty much win if the shot to your port looks like this

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[xsspeed]

Spence, what were your plans for your corona for intake? I assume you weren't going to spin the head, and with the 3s being on a tilt the intake side is very close to the firewall.

If you use ITB's and a plenum, I imagine you would get even closer/would possibly make sense ducting air up from between motor and firewall?

[R100]

Another idea is to fit 6x 45-50mm SU style carbs. Actually !!! Now that a fucking brilliant idea. Someone tell me im right. Or slam my idea. Opinions please.....

[Truenotch]

You're almost defnintely right^^

xsspeed - You're still better off duction from the front of the car as it's the clean, cold air that gives you the advantage. The best way is to do it similar to the earlier BTCC cars, they had a big plenium and a big duct heading to the front of the car that was 5-6" in dia.

[BobbyBreeze]

Another idea is to fit 6x 45-50mm SU style carbs. Actually !!! Now that a fucking brilliant idea. Someone tell me im right. Or slam my idea. Opinions please.....

Pretty sure SU's don't like being on their own runners. Maybe the piston fluctuates up and down too much with the varying pressure of a single runner. There must be a reason why you never, ever see them.

[Roman]

Hope you dont have a hotwire airflow meter Mikuni! haha.

Why dont you find some injectors with half the CC rating, have one inboard, one outboard, and the ECU triggering the pair of them?

Even at the best of times, avoiding fogging issues is a bitch apparently.

Also I'm fairly sure that the spray pattern for outboard injectors is way different to normal ones...

Needs to spray in a single narrow beam, rather than like a shower head?

Also keep in mind that when at full throttle full rpms, most factory injectors end up running at like 80-90% duty cycle.

To spray in one cylinder only for the duration of the intake event would require massive cc rating injectors with a very low duty cycle.

What are the bike ones like Spencer?

[Truenotch]

I'm thinking about machining a set of Silvertop quads out to 48mm and making a new throttle butterflies. There's definitely enough meat but it could be tricky.

Opinions?

Would also be keen to experiment with 45mm bike quads with outboards.

[mikuni]

From what we've established so far, silvertop ones are ok to use straight out of the box and have easy shapes. Blacktop are bigger, but funny shapes make them more difficult to use. From this it seems the logical solution is to machine the blacktop ones out to 48mm or possibly even 50mm if you a high output beams, k20a, f20c or similar.

[Truenotch]

Understood... I'm deciding what to do when the Beams eventually gets stood up... and taking the silvertop throttles I have out to 48mm might be a good option. Then it would be a 48mm hole straight through - round all the way. I assume blacktop ones would still retain their kidney shape on the back.

[mikuni]

True, the dimensions of that kidney shape might make things a bit difficult. The largest dimension of the kidney shape isn't more than 50mm so it should be possible to machine the entire thing out to what ever you want. Probably starting outside the throttle at around 58mm, dropping down to around 52mm at the throttle and 50mm after the throttle. The brighter section in by the throttle is perfectly round, then it is machined out to the ugly kidney shape.

Heres the comparison between a silvertop and blacktop throttle. This must be one of the early silvertop throttles because its different to the ones that are on my car and the manifold that I have.

Above you can see the silvertop throttle on the left is round, but below is the silvertop manifold and you can see the slightly off round shape to the port.

[Testament]

What about GTiR throttles? they had quads? anyone know what size? I guess they just aren't as common though.

[mikuni]

^ They are fixed together and the linkages are part of the intake manifold. They are kind of like DCOE carbs but throttle bodies, similar to the GT-R ones ten-five posted.

And as for dimensions, they are something like this (measured with a ruler )

(blacktop)

[Truenotch]

OK, so it wouldn't make any difference between the two. The hole would come out round in both cases and you'd need to make or adapt a butterfly either way.

[Truenotch]

[Spencer]

Spence, what were your plans for your corona for intake? I assume you weren't going to spin the head, and with the 3s being on a tilt the intake side is very close to the firewall.

If you use ITB's and a plenum, I imagine you would get even closer/would possibly make sense ducting air up from between motor and firewall?

I'm not doing that car anymore, was too much work at this stage in things, will just dort a ae82 for now. the plan was in the end to cut the fuck out of the firewall to fit the intake and plenum I want. Fliiping heads is out of the question. We looed into flipping the engine but couldnt find a gearbox. Looked into honda boxes and thought we were onto a winner with the K series gear, but turns out they spin clockwise not reverse like other Hondas.

With boring out the throttles, Glenn makes the butterflies to do it, Ive asked him and I can dig up the emails maybe. Its not as straight forward as it sounds, trouble is getting the shafts sealed I think. I know we are all poor but if your camming the beams etc you will be best off in the long run to go with some 50mm's after market jobs, possibly Glenns ones with his manifold. Its pretty much the perfect setup he will even to trumpets in different lengths ready to take outboards. Although he may be stopping to make allot of his parts. When your rich buy his long rods too will help it take the revs better

The bike carbs only go up to ~43 or 44mm too nothing bigger. even zx14 ones arnt bigger than the CBR1000 ones

What are the bike ones like Spencer?

I gave the set I bought to mike-e for his cart project as he is going to squirt that thing as the stock ignition parts are hard to find. But when I'm back I'm very interested to pull them apart and CC them and check out the pattern, they are denso jobs and have 12 holes in the head. I would say from the power they make on the CBR that they will be sweet on a blacktop. Just going to fit shorter trumpets I just scored and drill some holes in the stock plenum, spacing seems bang on.

[Roman]

I guess an advantage of boring out blacktop throttle bodies, is that they already have the larger diameter trumpets that bolt on to them, that you can get off the shelf bits for.

Although if the bolt spacing was the same on silvertop, could do the same thing and use blacktop trumpets I guess.

I've also been giving some thought to boring out my blacktop throttle bodies to a larger dia to suit the cross sectional area of the ports, but, its a lot of pissing around!

One idea that I've had, is to model the cross sectional area of the port in cad, and draw in the throttle bodies etc as per how they are now.

Then taking 'slices' of the model at say 10mm intervals and using cad to calculate the cross sectional area, then comparing this to see if the cross sectional area is increasing or decreasing or whatever down the length.

Then modifying the model in cad to give a proportional reduction in cross sectional area down the length.

then printing out the cross sections at 1:1 scale, and then using them as the basis by which to modify the ports, like you know that 10mm or 20mm from the base of the throttle, you know that it needs to be XYZ shape in order to have the right cross sectional area.

I think this is effectively what experienced engine builders do when porting heads and what not... But in a more oldschool sort of way, measuring with calipers and blah blah.

Rather most home port jobs, where people seem to think its a job for the eyeometer and a dremel. As if machining a mil out of everything is going to make their ports flow better, as opposed to actually analysing the shape and size of the port and coming up with a plan for what actually needs doing.

[Spencer]

So been looking into the staged code on the MS3 and it now does exactly what we want for staged injection. Its come along way from the first code implementation heres a snap from the megamanual you can see you can blend in secondary injectors in a RPM vs fuel load all sequential on a 4cyl

You can buy a fully decked out MS3 for $450 US so its going to be around $650 landed + GST. That gives you 8 injector drivers, 8 spark and 6 PWM/low volatge outputs for VVTi, idle control etc. I'll be getting one to play with for sure!

[xsspeed]

That is impressive pricing for that sort of ability. How does it trigger vvti? Can it be set up the same as toyota ex-factory?

Edit: Who is Glenn Spence? Is that the Celica_Ra45 chap from Ozzie?

I was planning on using the BT itb's I have on the 3s, and using probably putting ST itbs onto my BT (but I don't have a car for that at the moment)

If my memory serves me correct BT itbs are 45mm, ST are 43mm and facelift ones hav ethe teardrop shape. Again, IIRC if its the same guy, celica_ra45's ones were ~50mm?

[Spencer]

The MS3 needs a crank and cam trigger (which your motor has) then it simply outputs a PWM signal to the VVTi solenoid based on values from tuning/dyno time. Its not the best at the moment as you only get a 6x6 table you can tune it on MAP.MAF vs RPM or TPS vs RPM. You wont get it as good as toyota as they would have alot more resolution and probably a 4D table that works off MAF, TPS and RPM. So you will get it say 95% perfect but you wont get the part throttle stuff exact