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Rotrex restrictor sizes
- Thread starter mikekean
- Start date
mikekean
ClioSport Club Member
996 C4S, 135i, E30x2
Would be restricting the air going into the charger, like they do on turbo'd rally cars.
182, SQ7, Trafic
34mm is about right then but I wouldn't run on a standard engine with that.
I'm unsure if it will effect it more or less but I know from when I extended the intake and relocated the filter it wasn't making as much boost.
Do you have a picture of the FIA design?
mikekean
ClioSport Club Member
996 C4S, 135i, E30x2
From what ive been reading the closer it sits the more it restricts flow to the compressor so with a 34mm one sitting 50mm away its probably going to be running a bit down on boost compared to the setup your car runs. With about 6psi on a standard engine what sort of power would i be looking at?
http://www.adgespeed.co.uk/albums/parts/restrictors.jpg this is the type of restrictor that would be fitted.
http://www.adgespeed.co.uk/albums/parts/restrictors.jpg this is the type of restrictor that would be fitted.
182, SQ7, Trafic
That's what mine looks like.
I'd agree with what you saying so mounting that closer would in theory pull less air as further away the gap would almost store air.
I'd say running 1mm extra and mounting a bit closer your probably looking about 6psi.
I ran 231 with my rings shot. We reckon when first done (on an uncared for 120k engine) it was circa 250bhp.
mikekean
ClioSport Club Member
996 C4S, 135i, E30x2
Its not so much that it stores air, i thinks its more to do with the air doesnt have enough room to straighten out before it hits the compressor wheel so its effectivley not making use of the whole blade on the turbine.
If i could run 6psi and around 250hp that would be exactly what im looking for, I take it dropping the compression ratio would loose me power on a low boost setup? Was thinking standard compression forged pistons on standard rods with ARP bolts, ported head with one piece valves and matched inlets.
If i could run 6psi and around 250hp that would be exactly what im looking for, I take it dropping the compression ratio would loose me power on a low boost setup? Was thinking standard compression forged pistons on standard rods with ARP bolts, ported head with one piece valves and matched inlets.
you're ok on stock internals to about 0.5bar (7.5psi) you could probably do more, but give yourself a margin of safety. That should still see you around the 240-250bhp area
Fit a thicker head gasket, or a 197 head (larger chambers and a better inlet manifold design which is another bonus of that route) and you can see far more boost than that safely on standard pistons if mapped correctly.
Slightly different application, but my decompressed turbo engine using standard 172 pistons was peaking at just under 2 bar of overboost and then holding 1 bar for most of the rev range.
Obviously dont get carried away though as lower compression will lower the efficiency at lower boost limits, so if you arent running much boost dont lower the compression "just because" like some people do!
mikekean
ClioSport Club Member
996 C4S, 135i, E30x2
Id be limited to whatever boost the charger will make with the 34mm restrictor in place, unless you can fit a smaller pulley also? Was more just a query to see if standard pistons would be ok at 6-7 psi, been as i dont intend on changing the compression ratio would be a bit of a waste to fit forged pistons if i dont need them.
182, SQ7, Trafic
If your tracking it and hard use I would recommend upgrading what you can even for little boost.
The thing with the supercharger is that your using 10-20% of your power just to turn the supercharger. So in theory, if your producing 250 bhp at the flywheel yours pistons could be seeing upto and over 300bhp!
The thing with the supercharger is that your using 10-20% of your power just to turn the supercharger. So in theory, if your producing 250 bhp at the flywheel yours pistons could be seeing upto and over 300bhp!
Smaller pulley wont really make any difference if you have a 34mm restrictor before the charger, would be a huge case of diminishing returns, the charger simply cannot create anymore vacuum than almost a bar, no matter how fast you spin it, so the flow through the restrictor will be pretty much unaltered, but the parasitic load on the engine will increase.
182, SQ7, Trafic
Smaller pulley would just bring maximum boost in earlier, as chip says it won't have any effect with the restrictor.
Your boost goes up with your revs, with mine and my pulley in at maximum boost around 6k which makes it very nice to drive as it still feels like an N/A car and is a lot nicer to your gearbox.
If you were running 1.6 bar and wasn't getting 1.6 until 6k then you could have a smaller pulley so 1.6 came in lower down the rev range.
If you don't have a charger by the way mine is all for sale
Your boost goes up with your revs, with mine and my pulley in at maximum boost around 6k which makes it very nice to drive as it still feels like an N/A car and is a lot nicer to your gearbox.
If you were running 1.6 bar and wasn't getting 1.6 until 6k then you could have a smaller pulley so 1.6 came in lower down the rev range.
If you don't have a charger by the way mine is all for sale
Actually, you would find you would hit a higher boost potentially earlier in the rev range, but peak power (and boost at peak power) wouldnt be effected.
The restrictor has little effect at lower rpm, so you should be able to hit more boost after, but I was commenting on peak figures. (which if anything can be lower due to the extra losses)
The restrictor has little effect at lower rpm, so you should be able to hit more boost after, but I was commenting on peak figures. (which if anything can be lower due to the extra losses)
182, SQ7, Trafic
That's what I said..
Srry mate I obviously did a rubbish job of explaining myself, what I mean is, if you were geared for 1.6 bar at 6K like you suggested, you wouldnt just hit 1.6bar earlier on a smaller pulley, you might actually find that you high more than 1.6 bar at under 6K. But by 6K it will be back down to 1.6 bar again of course.
So for example you might see 1.8 bar at 5K
So for example you might see 1.8 bar at 5K
When the restrictor is pre compressor you will, because all it ultimately does is restrict the total airflow to X lbs/min, and at lower revs that same amount of airflow represents more boost.
mikekean
ClioSport Club Member
996 C4S, 135i, E30x2
All sounds pretty good, cheers for the info guys. Just need to try and work out how much of an effect having the restrictor that close will make. I want to see 6psi boost minimum really for it to be worthwhile 240-250hp would be plenty due to the extra torque, coupled to a sequential with only 950kg total weight it should go like a rocket.
182, SQ7, Trafic
Ah, nice one DannyR, reading fail by me there.
Sounds pretty well tied down!
Just a case of playing with pulley sizes then really.
Ultimately the restrictor is going to utterly prevent anything much over 300bhp at the crank no matter what charger or turbo you use, and then you have to subtract from that crank power the parasitic losses of the charger or the parasitic losses induced by increased pumping losses on a turbo.
A smaller pulley will see you head towards that power sooner in the rev range which will mean more boost and more torque, but it will also limit your power at higher rpm by introducing more losses and ultimately a drop in power from cavitation if you try and spin too fast, or a reliability issue with the turbo if you try to spin it too fast.
I think evebn with the restrictor you will easily be able to exceed the 250bhp you are saying you will be happy with on the right setup, but it might take a few attempts at pulley size to do so.
Sounds pretty well tied down!
Just a case of playing with pulley sizes then really.
Ultimately the restrictor is going to utterly prevent anything much over 300bhp at the crank no matter what charger or turbo you use, and then you have to subtract from that crank power the parasitic losses of the charger or the parasitic losses induced by increased pumping losses on a turbo.
A smaller pulley will see you head towards that power sooner in the rev range which will mean more boost and more torque, but it will also limit your power at higher rpm by introducing more losses and ultimately a drop in power from cavitation if you try and spin too fast, or a reliability issue with the turbo if you try to spin it too fast.
I think evebn with the restrictor you will easily be able to exceed the 250bhp you are saying you will be happy with on the right setup, but it might take a few attempts at pulley size to do so.
mikekean
ClioSport Club Member
996 C4S, 135i, E30x2
Ah ok i see what you are saying regarding pulley sizes, Id rather have more midrange than top end so be able to adjust that via the pulley size would be a benifit. Now the next question is what management do i go for? going to need something i can get a decentish base map for to do some testing with before getting it properly mapped..
Hi Racing-Friends,
I'm writing because I'm searching for an expert in using engines with turbo and air restrictor. I'm racing a car with 38mm air restrictor which must be placed 30cm in front of the compression wheel in a 2.0 TFSI from Volkswagen.
Right now the power is somewhere around 360hp an torque is about 460Nm. I have to upgrade to about 550Nm.
I got everything around the engine ready, except the turbo and the compression rate. Maybe you can help me with my last questions:
1. I have to use a turbo with K04 body. Might it be better to use bigger turbine and/or compression wheel?
2. Right now the enginge has a compression ratio of 9.8:1 Might it be better to low down the compression to somewhere around 9.3:1 to use higher boost? I have to use 100 Octan gaz.
I'm writing because I'm searching for an expert in using engines with turbo and air restrictor. I'm racing a car with 38mm air restrictor which must be placed 30cm in front of the compression wheel in a 2.0 TFSI from Volkswagen.
Right now the power is somewhere around 360hp an torque is about 460Nm. I have to upgrade to about 550Nm.
I got everything around the engine ready, except the turbo and the compression rate. Maybe you can help me with my last questions:
1. I have to use a turbo with K04 body. Might it be better to use bigger turbine and/or compression wheel?
2. Right now the enginge has a compression ratio of 9.8:1 Might it be better to low down the compression to somewhere around 9.3:1 to use higher boost? I have to use 100 Octan gaz.
Most restrictor engines (wrc etc) run high compression but it can make managing egt's a problem, especially if restricted on fuel choice.
You really need to be talking to a company that specialise in restrictor turbo competition use of that specific engine as trial and error yourself is likely to prove expensive.
You really need to be talking to a company that specialise in restrictor turbo competition use of that specific engine as trial and error yourself is likely to prove expensive.
