Good afternoon all,
I’ve finally had time to start completing the install the M45 Supercharger into my 2005 1.8 NBFL…
The kit I chose was from Salon Motorsports with the extra SR1 package parts from BOFI.
Everything is going well so far but I’ve now stopped as I cannot decide which route to go down with the throttle body setup…
I’ve spent a couple of weeks reading on and off about dual vs single throttle body setup but really cannot find anything that gives hard evidence that the dual throttle setup is better.
Most people seem to do it for the noise but surely having a single throttle body will limit responsiveness and feel stiff in the pedal and perhaps even cause too much back pressure?
The Salon motorsport kit has nowhere to bolt on a second throttle body to the inlet piping/bracket (where the bypass is located) so would mean fabricating and welding something up…
Has anyone tried to just re-locate the idle control valve from the orig throttle body to a pre charger location to keep idle good and then installing the original air filter box to keep it quiet with normal driving?
I’d love to hear from anyone or listen to any advice from anyone that has completed a successful M45 install on a 1.8 MK2.5 and setup that they are happy with 
I’m now officially confused!
Ps - I’m away at work for a couple of weeks and wondered if anyone has might have the measurements for the highlighted yellow question marks on the rough sketch below?
(Basically the dimensions for the flange side of the original throttle body on a 1.8 vvt)
I think you misunderstand the setup. It is dual throttlebodies, not twin. They are in line with each other. see THIS THREAD
No, I don’t think the OP has misunderstood… The Salon kit was designed to use the stock throttle in its original position and to have no throttle before the blower.
It relies on the blower bypass for recirculation to reduce off-throttle heat buildup and noise but I gather it’s still pretty loud (I haven’t experienced it to say for myself).
Dual throttles were developed to improve responsiveness when all available kits relocated the throttle before the blower, which increased throttled volume, especially if an intercooler was used in front of the radiator. With this kit, a second throttle would be to prevent the blower having to noisily pump dense air all the time.
Unless you use a Rotrex (belt driven Turbo basically) The Throttle body is always before the s/c as it is a true compressor, so shutting the throttle butterfly whilst the s/c still has an air supply would result in a pressure build up that will blow the butterly to pieces.
It really is nothing to do with noise or heat it’s purely to solve an idle problem and slighly improve throttle response.
Yes I know they are in-line…
But there must be a better way to do this…
Without having to install two throttle bodies and two cables…
I’m wondering if anyone has achieved a good setup by relocating the idle control valve to the supercharger side and using some kind of air box to reduce the noise of the charger.
I was as surprised as you were when i read that the Salon kit was not using a throttle before a PD supercharger, but that’s how they designed it, some years ago (repurposing Mini Cooper superchargers if I remember correctly).
I can’t picture what you’re proposing. The IAC valve has to route air past the throttle. It could pick that air up from anywhere outside the throttled volume with the provisos that it ought to be filtered to keep grit out of the engine, ideally it should be air at atmospheric pressure and it should have gone through the AFM to be measured (unless you have an aftermarket ECU and don’t use the AFM). Oh, and I recommend a check valve to stop boost pressure blowing air the wrong way out of the IAC valve. I ruined a valve by not using one.
I realise I am very late in responding to this thread, but here goes.
I too have been puzzled by the use of twin TB’s or the use of the original TB post charger.
The normal position for a TB is pre charger, so when I installed my Salon Racing kit some years ago I did the following, with great success.
I converted an old TB by removing the butterfly and spindle and blanking the holes created. This TB was installed on the inlet manifold with the existing idle control system, the air intake to the idle was fitted with a non return valve and filter to prevent pressure loss.
The original TB was installed pre supercharger with its TPS.
Salon do not provide a mount for this, so I created one using a TB mounting flange bonded to an aluminium tube with JB weld, the alloy tube was connected to the Salon inlet with a silicone hose and clamps, there was a metal support bracket between the rear of the supercharger and the TB as well.
This set up worked very well, the charger was almost inaudible when driving, until one applied a bit of throttle and it began to whine around 4K rpm.
Dual TB’s and dump valves are, in my opinion, a bodge to fix poor installation, any obstruction post charger creates noise, heat and a tendency to try and stall the charger when coming off throttle.
Just my view…
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Dual throttle bodies can have an advantage if you are using a high volume intercooler.
You keep the pre charger one open enough to keep pressure in the intercooler so that when you open the throttle you get better response.
They are a fiddle to set up properly though.
If you have no intercooler there is not much advantage.
A coldside supercharger is the best solution available.
My old MP62 charged car was nicer to drive once fitted with dual throttle bodies as the intercooler always had pressure in it.
