BenB
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| posted on 26/7/08 at 10:47 AM |
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Throttle bodies for a blow-through forced induction set-up
Does anyone know of some nice throttle bodies that will take high single figure boost?
I was planning on keeping it simple with my blower instalation and using a single 45mm Rover 200 throttle body but.... I've just realised that
maybe it's not such a good idea.
I'm using a Root's blower (eaton m45) and therefore will likely need an intercooler. Due to the lack of height (especially once I've
put throttle bodies on etc) I'm looking at a front mounted intercooler (air-air).
Apparantly upstream throttle bodies and intercoolers don't work very well because when you slam the throttle shut the intercooler will come
under a vacuum (which it might not like) and also there's all that air in the intercooler which will dampen the throttle response.
So... I'm looking for throttle bodies that will take boost. I know I could make up an air box to surround the throttle bodies and keep that
boosted (ie no spindle leaks) but surely there's a better way???
Ideally to keep things simple I'd like a single throttle body that will take boost @ flow enough to produce ~160Bhp but failing that which bike
throttle bodies will take boost?
TIA!!
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colt_mivec
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| posted on 26/7/08 at 10:55 AM |
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quote:
Apparantly upstream throttle bodies and intercoolers don't work very well because when you slam the throttle shut the intercooler will come
under a vacuum (which it might not like) and also there's all that air in the intercooler which will dampen the throttle response.
Use a BOV to stop this happening
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colt_mivec
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| posted on 26/7/08 at 10:59 AM |
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Are you thinking of having the I/C in the nose. To much pipework dampens throttle response
Would you be best building a charge cooler box that directly bolts onto the throttle bodies.
That way the air is cooled and the pipework is shorter,Then you can run the water/Coolant to another small air to air radiator in the nose.
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BenB
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| posted on 26/7/08 at 11:07 AM |
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True.... A chargecooler is an idea but then you have to have two radiators, a load of coolant, a pump (another one!!!!).....
I'm lead to believe a BOV is only of use with a turbo or centrifugal supercharger system... then again....
I was wondering- RS Turbo engines- do they have a blow-through throttle body??? Plenty out there (mostly highly polished...)....
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jamie1107
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| posted on 26/7/08 at 01:18 PM |
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i use gsxr throttle bodies with great sucess they will hapily hold up to 35 psi of boost
im not to sure why you would use an upstream throttle body because which ever way i invisage it it seems backwards your right about the intercooler
not liking vacuum tho
a charge cooler would be the way to go i intend to mount mine on the baulk head by the battery and position two radiators at the back of the car and
bring air in through some vents in the rear arches one rad for the turbo coolant and one for the charge cooler coolant
bike rads work well for this and come with tiny fans mercedes w140 and w210 use a auxilery pump for their air con which is ideal for the coolant
circulation and there is a guy selling charge coolers on ebay for £100 the flow rates should be ok for 5-7 psi of boost with a rover v8 im assuming
thats what your using
mounting the bits at the back will also improve your weight distribution a little i would also think about water injection to help with any knock
problems you may have again stick the tank by the fuel tank and offset the weight of that engine
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Volvorsport
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| posted on 26/7/08 at 01:22 PM |
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using a single throttle body isnt a problem with a plenum , what are you trying to achieve ?
all volvos are 55mm and upwards .
www.dbsmotorsport.co.uk
getting dirty under a bus
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jamie1107
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| posted on 26/7/08 at 01:23 PM |
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oops i missed the bov bit
i think you are thinking of a dump valve which is useless with a super charger the bov or blow off valve is basically like a safty valve you would see
on a steam engine if the pressure gets to high it vents it for you by means of the pintle inside lifting off its seat at the correct pressure which is
governed by the force of a spring on some valves this can be adjusted a bit like a fuel pressure regulator with a bolt on the top increasing spring
pressure thus raising the operating pressure of the valve
thats just the thing you need
fitted as standard to a nissan bluebird turbo im sure there are more thats the only one ive seen but you could spin one up on a lathe in a couple of
hours or even modify a dump valve
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BenB
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| posted on 26/7/08 at 03:06 PM |
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Power wise? 160Bhp...
The main advantage of a plenum and a single throttle body is it allows the plenum to be quite tall and give room from trumpets. The bonnet is quite
low relative to the top of the engine so if I have seperate throttle bodies with a plenum on top the plenum will be quite low and trumpets might not
be possible.....
and how much are gsxr throttle bodies? 
quote:
Originally posted by Volvorsport
using a single throttle body isnt a problem with a plenum , what are you trying to achieve ?
all volvos are 55mm and upwards .
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Ivan
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| posted on 26/7/08 at 03:49 PM |
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Interesting question and something I have never really thought about - if upstream of the supercharger it puts the whole system under vacuum on a
trailing throttle - possibly good for charger and belt but not for pipes and intercooler. If downstream causes cavitation in the blower under trailing
throttle if you don't have a blow off valve - never a good thing.
Which is best - I don't know - will read up for interest when I have time in a week or so.
Would guess that downstream of charger near inlet plenum with Blow Off Valve between throttle body and charger is best.
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BenB
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| posted on 26/7/08 at 04:27 PM |
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I'm heading towards a downstream throttle with a recirculating blow-off valve to bypass the blower....
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Ivan
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| posted on 26/7/08 at 04:41 PM |
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quote:
Originally posted by BenB
I'm heading towards a downstream throttle with a recirculating blow-off valve to bypass the blower....
Not sure what you mean by "recirculating" but I wouldn't, why keep hot air in circulation - blow it to waste. Normally you
recirculate for throttle response reasons and I don't think that will be your problem.
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BenB
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| posted on 26/7/08 at 05:05 PM |
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A recirculating BOV just bypasses the blower therefore allowing the pressurised air back into the blower inlet.
With a fixed displacement blower like a Rootes that's not such a bad idea as you don't have a compression ratio therefore no pressure = no
heat. If you dump it to atmospheric meanwhile you use up Bhp to suck air through the filter only to dump it out again....
If the blower has a compression ratio then blowing to atmospheric is much better....
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jamie1107
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| posted on 26/7/08 at 06:34 PM |
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think i payed 40 from ebay for the last set with tps and injectors rail etc they are a 46 mm taper type if you need any photos give me a shout
ive seen 2 sets fitted to a rover v8 before the reason i use them is because we build alot of race engines so you need the throttle responce of bodies
they weld quite easily to the inlet manifold if you want to go that route but with super charger boost i would just use silicone hose and jubaliee
clips you can use hose and wiggins for up to 25 ish psi but i wouldnt like to
there is also a mod to allow full 90 degree butterfly operation as the uk models are restricted just a matter of removing some metal from the stop
think thats it i think forge do bov s for under a ton i wouldnt bother with recirk ones they are really meant for cars running hfm sensors besides if
you vent it to air it sounds nicer
if you only want to run 180 horse you wont need much boost so im guessing you will be using stock pistons in which case depending on your boost
cooling choice you will probably get away with just using knock sensing providing your ecu supports it
failing that run with no cooling and use water injection aqua mist do a kit or three but they are silly money but you can put one together for under
100 working on boost pressure independant from your ecu all depends on your management
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paulf
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| posted on 26/7/08 at 08:26 PM |
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I think most bike throttle bodys would take a small amount of boost, the ones I have seen have either ballraces with seals or bushed and sealed
spindles.As mentioned GSXRs would work and I know cbr 900 throttle bodys will take boost as I know of a car fitted with them and a turbo.Short bell
mouths would probably be ok with forced induction as its not quite as important to have a tuned length.
Paul
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Benzine
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| posted on 27/7/08 at 11:58 AM |
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I don't know where to put my throttle body now T_T I thought before the supercharger was best but I guess that didn't take intercooling
into account.
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jamie1107
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| posted on 27/7/08 at 12:20 PM |
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i would go air filter into super charger then through intercooler or charge cooler cant recomend those enough without writing an sa about heat soak
lol
then through your throttle body or bodies pop the bov in the line between the charger and the throttle body
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BenB
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| posted on 27/7/08 at 12:37 PM |
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Yup. That's the plan now. Looking at buying a RS Turbo throttle body. They have exactly the same set-up and they're cheap as chips...
Even found a dinky little intercooler on Ebay. Just go to find out what surface area I need by doing some maths....
Nice set-up. Nice and thick, fairly tall for a given width etc etc..... Quite why so many intercoolers are wide and short I don't know. Gives
very few tubes so high pressure losses... A narrow tall IC will always be better than a wide short one... Check those end caps as well... Perfect
design....
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alistairolsen
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| posted on 27/7/08 at 01:47 PM |
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you always have heat, otherwise you wouldnt need a cooler.
the reason for recirc valves has nothing to dow ith heat and everything to do with engine management, if you run an air mass metering system you
cannot simply vent metred air and expect the fuelling to cope.
as for ITBs, I woulnt bother, lots of hassle and the only gain is in throttle response (tiny gain) Its also a pain in the arse to map properly.
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jamie1107
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| posted on 28/7/08 at 12:44 PM |
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you do realise the rs turbo has no useable throttle position sensor on it
the tps it comes with is a 3 position switch so is useless if you want to run an ecu you would be far better off with a mondeo body preferably the 2l
model
as for a dinky intercooler i cant quite see the point in that unless the air flow is sufficient which just looking at it with the words v8 in the back
of my mind its not
you also need to bear in mind if you stick it infront of the rad it will impeed the flow of air through the rad and if you stick it on top of the
engine you will get heat soak from the engine itself
this is why charge coolers are such a good idea while you are sat still your intercooler is doing nothing even worse if its on top of the engine then
its soaking up all the heat from the engine so when you go to drive it hard you need to get rid of that heat before you can start cooling the boost
depending on what boost you want to run then you may not need either if you are looking below 7 psi i would sugest water injection this is a far more
cost effective and efficient method
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BenB
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| posted on 29/7/08 at 08:57 AM |
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It's far from a V8 though 
1098cc V4 bike engine!!!
I didn't know about the rubbish TPS on the escort throttle body!! pants 
I'm not so sure about the premise that recirculating is only to avoid confusing the air flow sensor. Most books I've read suggest
it's a better idea to install the MAP sensor after the throttle body (and therefore the blower) therefore it doesn't matter whether you
recirculate the air or blow it of. It's more to do the fact that with a centrifugal or turbo you build-up heat and therefore lose energy by
re-circulating but with a rootes you don't make heat and infact save energy by just recirculating your filtered air.
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johnston
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| posted on 29/7/08 at 09:23 AM |
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I always thought an intercooler wasn't really necessary on a supercharger asits not producing the same heat as a turbo..
I.e. its not absorbing any from the exhaust side of things..
As for a single throttle body i got 1 of a skyline cheap but there's bound to be plenty from the likes of blown up/crashed cavelier/calibra
turbos, cossies, evos and scoobies floating about??
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BenB
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| posted on 29/7/08 at 11:09 AM |
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With a turbo some of the heat (in fact a fair bit) comes from the exhaust side of things (turbos glowing red hot etc etc)- the centrifugal type
compressor used is quite efficient. But they don't make much low-end boost. I'm using a Rootes type compressor which has max efficiency of
60% (lots of heat!!). However, it has the advantage of a nice linear boost map....
With the PSI I'm looking at an intercooler is a necessary item (or charge cooler!!) unless I'm going to run it on AVgas The outlet
temperatures from Rootes type blowers get quite scary!!! That an a relatively high compression ratio of 10:1 make detonation a possibility. With a
cooled intake mixture I'm more likely to be able to map the ignition timing to where the power lies!!!
Just re-read the Corky Bell bit from "Supercharged" on intercoolers. He seems to say chargecoolers are good for single shot ice-packs on
drag races but otherwise their complexity and weight burden makes air:air preferable......
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