ECUTune Stage III twin screw supercharger sign up

[timbo3185]

can anyone tell me what power this car has?

[AFBeefcake]

No car with the ECUtune supercharger has been tested yet, but estimates according to www.ECUTune.com are around 345 hp (50% over stock) at the crank.

[mbtoloczko]

Assuming that the power scales with the amount of boost, then the approx HP is around: 230*(14.7+7)/14.7 = 340 bhp. SCs have some parasitic losses though, so I'd guess the max HP at 7 psi would be around 320 bhp.

[longassname]

I got a wisdom tooth out so I haven't been working but I'm back to work now.

[longassname]

that equation could actually use a little revision.
230 hp at 95% ve
(14.7 + 7)14.7 = 147.5% ve
147.6/95 = 155.4% increase at 5600 rpms
new peak at 6500 rpms
6500/5600 = 1.16
1.55 * 1.16 * 230 = 413.5 hp at 6500 rpms

let's not get caught up in playing with numbers though. It is what it is and we'll measure it soon enough.

Originally Posted by mbtoloczko

Assuming that the power scales with the amount of boost, then the approx HP is around: 230*(14.7+7)/14.7 = 340 bhp. SCs have some parasitic losses though, so I'd guess the max HP at 7 psi would be around 320 bhp.

[longassname]

There is still space in batch 2. I'm still working on getting batch one out. Batch 2 will be quicker though since I'm making all the parts which don't require core parts in a large enough quantity to cover both batches. There are a few others waiting to get in on batch 2 as well but I haven't accepted payment from anyone yet. After I get the first run squared away I'll give a holler out that I'm accepting official orders. In the mean time, welcome aboard--this seems to be the offical supercharger kit of the US military

Originally Posted by Xevious

If there's still space (this thread's so long I'm not sure who all is on for the second batch), I'd like to get on the bandwagon.

Since I'm in iraq, it's hard to get my intake to you, and since I want to buy another engine anyway, could I just ship the entire engine to you?

If I'm missing some dreadfully important info, lemme know.

Thanks,
Gabe

[mikecg]

Hey mike,
Have you sent out the finalized software yet? I'm not rushing you, I just wanted to make sure it isnt lost in the mail somewhere. I 6-speed is nearly completed. I believe the only hold up is getting our hands on some srear shafts to go with the R180 rear. Hopefully it'll be rolling out next weekend.

[longassname]

Nope, it'll go out this week. Would you prefer I send it to Tom instead of the address you gave me?

Originally Posted by mikecg

Hey mike,
Have you sent out the finalized software yet? I'm not rushing you, I just wanted to make sure it isnt lost in the mail somewhere. I 6-speed is nearly completed. I believe the only hold up is getting our hands on some srear shafts to go with the R180 rear. Hopefully it'll be rolling out next weekend.

[SVXfan01]

So with the SC kit, We won't need to switch it to a standered shift? Say we wanted to whats the best tranny to switch to. Please Im alittle Retareded when it comes to the abriviated names so just tell me from what car the transmission comes from and I'll be happy =)

[TomsSVX]

6mt= 6 speed manual tranmission. These are the strongest manual gear boxes subaru has available. The auto can also be used, Mike however prefered to destroy his front differential and he wanted a standard anyway.

Tom

[mbtoloczko]

Originally Posted by longassname

that equation could actually use a little revision.
230 hp at 95% ve
(14.7 + 7)14.7 = 147.5% ve
147.6/95 = 155.4% increase at 5600 rpms
new peak at 6500 rpms
6500/5600 = 1.16
1.55 * 1.16 * 230 = 413.5 hp at 6500 rpms

let's not get caught up in playing with numbers though. It is what it is and we'll measure it soon enough.

Common, how can you expect me to not reply to this? Why would boost change the peak power rpm? Are you doing cams too? If not, I'd expect the peak power to at almost the exact same rpm as stock. Here's a dyno plot showing the result of a turbo kit on an Impreza 2.5 RS (factory non-turbo, 10:1 compression ratio). Peak power is actually at slightly lower rpm. My bet is still ~320 bhp (at 7 psi boost).

[longassname]

that's what you aren't getting conceptually...this is a positive displacement blower. The power plot of an engine with a positive displacement blower is not the factory plot raised; it is a 45 degree angle line. The volumetric efficiency of the engine is being replaced. Your peak rpm is your peak power.

Originally Posted by mbtoloczko

Common, how can you expect me to not reply to this? Why would boost change the peak power rpm? Are you doing cams too? If not, I'd expect the peak power to at almost the exact same rpm as stock. Here's a dyno plot showing the result of a turbo kit on an Impreza 2.5 RS (factory non-turbo, 10:1 compression ratio). Peak power is actually at slightly lower rpm. My bet is still ~320 bhp (at 7 psi boost).

[Phast SVX]

Originally Posted by mbtoloczko

Common, how can you expect me to not reply to this? Why would boost change the peak power rpm? Are you doing cams too? If not, I'd expect the peak power to at almost the exact same rpm as stock. Here's a dyno plot showing the result of a turbo kit on an Impreza 2.5 RS (factory non-turbo, 10:1 compression ratio). Peak power is actually at slightly lower rpm. My bet is still ~320 bhp (at 7 psi boost).

and above that, look at the huge tq loss from 3-4000rpm, that car definetly has some tuning issues. Wonder why they didnt plot afr :/

[mbtoloczko]

Originally Posted by longassname

that's what you aren't getting conceptually...this is a positive displacement blower. The power plot of an engine with a positive displacement blower is not the factory plot raised; it is a 45 degree angle line. The volumetric efficiency of the engine is being replaced. Your peak rpm is your peak power.

According to the Whipple website, a Whipple SC makes peak boost at relatively low rpm and then the boost holds steady out to high rpm. This isn't much different than raising the pressure of our atmosphere. There may be some shift of the peak power due to raising the values of the torque curve, but because peak power on an OEM SVX motor drops off rapidly after approx 5700 rpm, my guess is that with the SC, the peak hp will have a broader plateau that is shifted a bit to higher rpm rather than increase linearly as you are saying. Just because there is an SC on the motor doesn't mean that camshaft profile looses all significance.

[longassname]

I'm afraid you are mistaken. I'm not trying to argue with you; I'm taking time away from my busy day to explain something to you about which you have some missunderstandings.

A positive displacement blower locks a certain amount of air in between the lobes of its rotors. With each rotation of the rotors that fixed amount of air is forced out of the blower and into whatever it is bolted to. Turn it twice and now you've pumped twice as much air. When plotted against rpm the air pumped is 1 rise over 1 run, a 45 degree line with it's peak at the highest rpm. This is the plot of all positive displacement blowers, both roots and twin screw blowers. With a roots blower however, the pressure in the chamber into which it is pumping against can cause backflow into the blower and muck up the whole process. If the pressure is too high who knows what the plot would look like..it would just be a mess. The twin screw blower does not have that short coming. A twin screw blower can pump against massive pressure without any backflow. That is actually their primary use. They are used in comercial applications for high pressure air compressors. The plot of the output of the twin screw compressor is basically always going to be a 45 degree line.


An engine is also an airpump and it's power output is mostly a function of its air intake. The engine has a defined displacement and with each revolution presents a certain volume into which air can flow. The amount of air which actually flows into this volume at any given rotation speed vs the volume is the percentage we term volumetric efficiency. The shorthand of which is VE. The volumetric efficiency of a naturally aspirated engine varies with rpm. It is typically pretty low at low rpms, say 80%. It typically increases with rpms up to the torque peak and then decreases again. This is why power drops off at high rpms on a naturally aspriated engine, volumetric efficiency drops off. The increasing rpms above peak torque are enough to sustain an upward slope of power up until it's peak power which is slightly higher than peak torque but from there it is all down hill.

Now when you bolt a positive displacement blower to an engine the volumetric efficiency of the engine is replaced with the blower's. If you are spinning it at a speed that puts out 50% more air than the displacement of the engine then ve is 150%. So at low rpms you've gone from something like 80% to 150%. At the old torque peak you've gone in our case 98% to 150%. At the old peak power point you've gone from 95% to 150%. The shape of the old ve plot and the power plot which it determined are not determining the shape of the new power plot. The amount of air going into the engine is going to be 1.5 times as much as the displacement no ifs and or buts. If there was such a restriction that it wasn't able to get past the valves the air would still be trapped in the manifold as the compressor continued to pump and your manifold pressure would start increasing with each revolution. 7 and half pounds would quickly become 9, 10, 11, 12, 13. We would quickly know we have a problem. We don't.


Looking at "boost" with a positive displacement blower is really looking at a symptom not at the cause we are creating. We don't have to look at boost to see our increases. What we really look at is input shaft speed. We know how much air we are pumping if we know what speed we are turning the blower at. This is what really tells us our gains, not boost. Boost is effected by temperature so if we go by boost our estimates are inflated.

If your really want to play with #'s, which I still discourage you guys from doing since it always leads to me having to re-explain how to do it right, the correct #'s to start with are:
1.6 liters per rev
4.2" crank pulley
2.3" supercharger pulley.

That is the setup on mike's car. You can then take your stock peak power, multiply it by ratio of the new ve to the old 95% like I did above and then draw a 45 degree angle line through that point. That's your new estimated power plot.

But come on guys...do you want me re-explaining this again or do you want me making parts?

Originally Posted by mbtoloczko

According to the Whipple website, a Whipple SC makes peak boost at relatively low rpm and then the boost holds steady out to high rpm. This isn't much different than raising the pressure of our atmosphere. There may be some shift of the peak power due to raising the values of the torque curve, but because peak power on an OEM SVX motor drops off rapidly after approx 5700 rpm, my guess is that with the SC, the peak hp will have a broader plateau that is shifted a bit to higher rpm rather than increase linearly as you are saying. Just because there is an SC on the motor doesn't mean that camshaft profile looses all significance.