Throttle bodies or single TB

[Redmohawk]

Ok been looking at Betty and trying to work out where/how to fit the super charger etc . Throttle bodys for a GPX600 have pain in the ass spacing of 68mm-91mm-68mm and adapting a set of TB's off something like a GSXR600 is do-able but I'm thinking more space in there would be handy for the supercharger etc

So my question oh great orical is :-

Would a single larger TB off a car etc with a log manifold with injectors firing down ports (replacing the multiple TB's) Be a better (easyer) option ????? I realise it's a backward step performace wise going back to a a single TB , but the ease of instalation and room gained for other parts such as supercharger intercooler etc. Please keep in mind the plan is for me to do the majority of the work (if not all).

[Large]

If you run a single throttle body, do you still run injectors to each cylinder?

[Redmohawk]

Yeah mate just like a car manifold on new stuff TB at one end , log manifold with outlets for each cyl with injectors mounted in outlets pointing down intake ports at valves , or even machine ally intake runners on head to take injectors (there quite long around 40mm).

Thinking that may be the way to go to save even more room, some modern cars have the injectors squirt onto the valves to increase atomisation and cool the intake valves as well. There isn't much room on the 600 for all the shit I'm planning on shoving into it so every little bit counts. I'm assuming that the log manifold wont be to stressful/problem as it will only be air moving through it and under pressure at that! Modern cars that i have worked on with the same setup from the factory dont seem to fussy about equal distrbution of air/path etc. Though i have seen 6 cyl log manifolds with a second TB put on the other end have increases in horse power of 10 Kw or more from that mod alone.

What I'm looking for is info basiclly saying IT WONT WORK BECAUSE OF (bla bla) or YOU NEED TO MAKE SURE X IS THIS ETC otherwise I'm giving it a go! haha

[Redmohawk]

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The plan as of now . Intercooler mounted in between rear frame rails with supercharger at the front right of bike. Piping should be self explanitary with single TB on left side of bike. Thanks to jason for being the hand model lol. Expolded view of supercharger for those that might be interested.

[Deano]

it will work but off boost throttle response will be non existant.

throttle response is your friend beleive it or not. i think Exben tried this years ago.

the intercooler will be all but useless there. mostly cause it will get fuck all air and it will be so small once you add tanks that are 40plus mm wide it could end up restricting things and making life worse not better. if you run some ducted air to it you might be right.

also i assume you rejetted the bike to suit the pod filters and a lack of fuel wasn't causing the problem at afr.

i would run likes of gix600 tb's and respace as they are easy to do. don't run the intercooler till you no if you have to. see what the intake air temp gets to. if you have sized things correctly you will not necessarly need one.

[Redmohawk]

Thats the point dude there is no off boost , is constant at what i set it from idle to readline thats why I'm using a supercharger.

Yeah ducting is a must (knew that) , big scoops for ramed air eather side of tank is the plan using original brackets on tank, with an exit cowl for air to exit, without mud shit etc from rear tyre hitting intercooler. Plus theres not alot of room at the front as it is.

The bike had the stock airbox at AFR10 taking bike into a mates on Tue to solve mistery 6000rpm intermitant rev limiter.

Thanks for the input though dont mean to sound unaprecitive , your info is the sort of stuff I'm after. I realized a Single TB will reduce responce , but do you think it will be significant enough to cause issues around town ? This will never be a race bike except for a few passes down the drag stip anyhow haha

Yeah thinking of doing it all in stages EFI sorted first then super charger at 4 PSI then maybe intercooler and up the boost. I want 120rwkw and now have 3 motors of similar condition and vintage/mileage to play with so if one goes bang in the hunt for power well i wont be broken hearted.

[Deano]

i guess give it a go then. but don't be surprised if you change over to multy throttle. easier just to do multi throttle from the start.

sometimes the simple things in life are not the best

[Benz]

I reckon throttle body in front of the charger, so you have vacuum at idle, and instant boost when you open the throttle, no lag at all.. A 600cc engine spinning a blower capable of 18psi into an 1800cc engine....so 54psi at 45000 revs?? Stupid......so spinning the blower three times slower will still give you 18psi, still plenty enough to blow UP your engines!! You could just about run that at 1 to 1.......... couldn't ya?
Should be interesting......
Keep us posted

[Redmohawk]

Yeah i hear you deano might just go the multi and bite the bullet, just got the right size single here and finding multi's without going for a trip to melb isn't likley (at a resonable price anyhow).

Benz Yes your right if i was just directly mounting the charger to the engine 1 to 1 would be a possable option or at lest a much lower ratio but The charger being centrifical will make bugger all boost into a lawnmower at less than 10,000 rpm and i want 4 psi from as close to idle as i can get hence the 4 to 1 ratio giving me around 5,000 SCrpm. Yes I have a plan for the 11,000 red line nope i dont want upwards of 60 psi into pore old betty, Magnetic slipper clutch computer controled to limit SC rpm to a safe level and boost to what ever pre set level you like. This way I limits the need for a blow off valve (but will have one for pressure contol on fast throttle closure (and a cool woosh sound lol)) and also limits power used by the SC to only whats needed to compress the air (no wasted bleed air from a waste gate etc) The clutch can transmit up to 15 hp while still alowing some slip and is very responsive .

[Deano]

if you were going single i would just use 1 tb off a set of busa tbs. if it is before the charger. the smaller the tb the better the throttle response.

don't no if i would want boost that low. that means even when you are cruising down the road at 5% throttle you are making alot of boost. hard on the motor and also the fuel economy. i would want it boosting a little later than that i think

[hyofighter]

redmohawk , couple of things from my experiance when i supercharged my pulsar , originally it was a turbo i left the trottle body where it was at the manifold , as a turbo at idle no boost with the supercharger at idle it had boost to be expected so the need for a bypass or blow off is a must , but in saying that i dont know how much a centrifical charger would make at idle as mine was a positve displacement style , the supercharger i used was a sc14 off a 2ltr toyota 6 i put it on a 1.5ltr 4 cyl i span it at the same speed as it did on the 2 ltr and at the factory 7-8 on the toyota i was thinking at the time a possible 2-3 psi increase on the 1.5 as its only a 1/4 of a ltr less this theory does not work i ended up with 13 psi but i was happy with that as it was intercooled , you could possibly get away with 7 psi on your motor with out an intercooler but you definatly would have to decomp it to do this 4 psi on the standard motor would be okay , personally id stick to a single trottle for simplisity but size of the throttle and plenum size can make a huge difference to throttle response air speed and in some cases plenum design can effect each cylinders air delivery , all the big horsepower jap cars like the gtrs ditch the multi throts for a big single

my 2 cents only , i had a lot of fun supercharging my car and also wanted to burn it some times but the end result was something different that worked

one last thing i have a 10psi over boost valve here at home if your intersted , its just like a pressure relief valve just spring loaded not vac controlled , you could use it to control the super charger from going any higher than that

[Benz]

I've had a SC 14 on my commodore VL for 8 years. Fitted the throttlebody in front of the SC, and the car drives just like a N/A, except it has 6psi when the throttle is opened, and that makes a hell of a difference to low down torque. I can even turn it off as it is fitted with the same style magnetic clutch as an AC compressor. I tried other setups, but the TB in front is the go for driveability.The SC doesn't mind spinning in a vacuum at idle and low revs, and the stock Mass Air Sensor in front of the throttle body doesn't know the difference, except for MORE air when the throttle is opened.......... works perfectly.

[Redmohawk]

Hmmmmm, more to think about lol. I had a toyota celica that went through stages of a 2tg (1.6L 4 cyl twin cam 2 valve head 6000 rpm) with sidedrafts to turboed 2tg with injection then to a 1GGz (2L 6 cyl twin cam 4 valve 6500 supercharged factory ) then turboed the 1GG intercooled upped boost to silly levels . I did all the spanna work and got it up and running , but all the injection programing was done in melb drive in slow , wheelspin out . Engine power was so high i was banned from calder street meet for to fast without cage and licence etc . Chassie cracked just behind driver side front strut after to many traffic light races so body was scraped and running gear sold to make way for kids lol.

Deano :- not real concerned with fuel economy on the bike to much it will always be better than the big bad Burtha (the 302w powered coaster bus I drive), and with the significantly increased torque i could just change the gearing to compensate a little.
The boost a low rpms shouldn't be to big an issue i would think , roots chargers like Hyo and Benz used on there cars do have clutches that disengage at idle but most just leave them run all the time with little adverse affect and they generally run a steady boost level right through the rpm range from idle to readline if sized corectly.

Hyo :- the significant increase in boost from 2L6 to 1.5L4 could be put down to reduced engine efficiancy those 1GG6's breath real good with 4 valve twin cam heads (my car reved to 10,000 rpm factory internals aftermarket comp and lots and lots of tuning ) Little 1.5 pulsar motors do ok but far less ability in the head to take extra air means more presure build up in the manifold . I think most of the really high output drag cars running big boost give the mulipul TB's the fick and bolt on a single is because there going to huge volume log manifolds (usally between 2 and 3 times engine volume) and its just easyer for them. Throttle responce isnt a big issue as there just belting down the stip mostly. Most circut track based high performance high reving cars with factory backing use multi TB's both natural asperated and boosted.

Benz :- Yeah I've seen a few toyota superchargers fitted to holden V6's is a great easy job for some quick torque improvement, there is a guy here in shep with a twin charger arangment on a late model V6 in a early gemini sounds wicked and goes harder than most would think. He helped Rod hadfield from castle main develop the bolt on kit for them.

Now I'm more confused then ever! I've never seen a TB mounted before a centrifical supercharger before. I have seen it done with turbos and with roots chargers it's very common, usally with carbs though . I'm thinking mounting the TB before the SC would possably reduce stresses on the motor??? to some extent as the charger will have to ramp up boost as the air supply is avalable, granted this may be very quick as the SC will be spinning at a significant speed in a partial vacuum. But as Deano points out this will reduce throttle responce compared to multipul Tb's after the SC. I might pm booster and ask him to look in on this thread I think he knows a lot more about this subject than most.