• There has been a recent cluster of spammers accessing BARFer accounts and posting spam. To safeguard your account, please consider changing your password. It would be even better to take the additional step of enabling 2 Factor Authentication (2FA) on your BARF account. Read more here.

supertrapp exhaust and cooling on F4i engine

Friggin Chi said:
put a car muffler on it like a turbo muffler its cheap flows well...
yes, the Sonic Turbo is cheap, light, and quiet (until you blow the fiberglass out of it). Have you looked inside a Flowmaster? they totally look like someone's high school welding assignment. but they work because of standing waves. I'll bet you could make a muffler of that design that was quiet at 10,000. ;)
 
Friggin Chi said:
...it uses sprays water on the radiator... damn the judges...
don't the new Evos (or is it the WRX?) have this? I heard the autocross organizers banned the use of it because it might leave fluid on the course. anyone know the story? (I know we have Evo and WRX owners, as well as autocrossers on BARF.)
 
but yes, it will take a little trial and error to figure out the new dipstick reading

xtasie99 said:
... in previous years we've used an accusump, which is an extra 3 or 4 quarts of oil that gets plumbed straight into the oil pickup...
However, the accumsump doesn't pull those extra quarts of oil out of the engine until the motor is running, so for a while we run like twice the amount of oil as the engine was designed for...
The Accusump applications I've seen were plumbed from a single pressurized point (e.g., where the pressure gauge attaches), and had a valve (either manual or electric), so you could pull into the pit (or driveway) and rev it up to full pressure, close the valve (trapping the extra quarts in the Accusump under pressure, and leaving the usual amount in the pan), then pre-oil before start-up by opening the valve.
 
hmm, a fluid storage sump....

I haven't seen for sure, but I'm guessing you can't put a funnel, chiller, or blower ahead of the restrictor; everything must come after, yes? So how can we suck air through the restrictor at maximum velocity all the time, not just when the engine is screaming? Obviously, there's some physical limit to how fast the air can pass through that restrictor (let's say 300 mph), and there's some point below that (let's say 100 mph) where it costs more power to suck a little more air through than you can make from that little more air. In those moments where the engine is not at full revs, and would be sucking at a mere 10 or 20 mph, can we rig up something that will continue to suck air through at 100 mph, and store it somewhere (e.g., in the previously mentioned giant airbox), under pressure, like an Airsump? how about a big, heavy turbo? spin it up before the start, and its stored rotational energy will continue to suck air through, even when the engine revs go down when you drop the clutch. How massive would it have to be to continue to spin for the whole course? It doesn't need to stay at full speed the whole time, just stay ahead of the engine's needs, so there's always pressure in the airbox, not vacuum. Overpressure could be routed back in front of the impeller (behind the restrictor), allowing it to freewheel once at max pressure (I'm thinking 5-7 psi).
 
Re: hmm, a fluid storage sump....

Cygnus said:
How massive would it have to be to continue to spin for the whole course?

I would think something with a flywheel no more than about 500-600lbs. should do the job as long as you can spin it up to at least 20,000RPM initially. ;)
 
From the rulebook:

"In order to limit the power capability from the engine, a single circular restrictor must be placed in the intake system between the throttle and the engine, and all engine airflow must pass through this restrictor.

Any device that has the ability to throttle the engine downstream of the restrictor is prohibited."

Turbos/superchargers:
"Turbochargers or superchargers are allowed if the competition team designs the application. Engines that have been designed for and originally come equipped with a turbocharger are not allowed to compete with the turbo installed. The restrictor must be placed upstream of the compressor, but after the carburator or throttle valve. Thus, the only sequence allowed is throttle, restrictor, compressor, engine. Only ambient air may be used to cool an intercooler."
 
Re: Re: hmm, a fluid storage sump....

OldFatGuy said:
I would think something with a flywheel no more than about 500-600lbs. should do the job as long as you can spin it up to at least 20,000RPM initially. ;)
I was thinking more like 20-25 lbs at 100,000 rpm (same energy as your example, right?)
 
Re: Re: Re: hmm, a fluid storage sump....

Cygnus said:
I was thinking more like 20-25 lbs at 100,000 rpm (same energy as your example, right?)

I dunno. I was just being a smartass. :p
 
i don't see any reason why the fan has to provide 'uniform air flow'. routing oil coolers everywhere seems like a pain. just about any big ass shrouded fan should do the trick. as for the electrical draw, that alternator probably puts out 20A @ 5k rpm. with no lights or other BS, you probably have close to 15A excess capacity, even at 5k, let alone 10k. my understanding of the motorcycle alternators is that they are always running, and that excess charge is simply dissipated by the rectifier. so, it's not like drawing a load is going to do anything to the HP. is this incorrect ?


-everyone here is all keen on water wetter, but that's only because they won't let you use real coolant on the track with motorcycles. use something better, like engine ice.

-it seems that if you have to use a restrictor, you should restrict the throttle bodies too, to provide a uniform flow.

-vacuum the crankcase is supposed to be good for at least +1HP

-decking the head should be worth a few HP

-use VP-U4, that should be good for +6% HP.

-to beat the sound requirement, just rewire the tach, so 10k indicated is really 7k.)

-maybe you should pressurize the frame with NOS, and just vent it near the airbox, or any number of ways to introduce it.

after all of that tuning, like motorcycle racing, the driver will still win it or lose it. maybe you should recruit a 50lb 8 year old from the local kart track.


if you want something radically different, how about leaving the engine revving at a constant 10k, and work on a traction control system based on an external clutch ? after all, that's where the HP exists, not at 5k.
 
PantyBuncher said:
i with no lights or other BS, you probably have close to 15A excess capacity, even at 5k, let alone 10k.

Yeah, thats about what I remember. However, the bigger the fan, the heavier it is. So really it should provide adequate airflow, and no more.


-everyone here is all keen on water wetter, but that's only because they won't let you use real coolant on the track with motorcycles. use something better, like engine ice.

If I remember correctly, nothing other than water wetter allowed. It's something like that.

-it seems that if you have to use a restrictor, you should restrict the throttle bodies too, to provide a uniform flow.
Why? Once the airflow is restricted, you can do whatever the fuck you want and it won't make a difference (other than hurt you). They purposely leave the door wide open, in order to make us figure out the optimal solution. You can run a huge assed throttle body, but then you lose throttle resolution. There is an optimum range.


-vacuum the crankcase is supposed to be good for at least +1HP
Very true. They make us run a crankcase overflow thingy, so you have to fab a pressureized container. We have one.


-decking the head should be worth a few HP
it would provide more low end, but once you're out of air, you're out of air.

-use VP-U4, that should be good for +6% HP.
Duh. Rules.

-to beat the sound requirement, just rewire the tach, so 10k indicated is really 7k.)
Yeah, but thats straight up cheating, and an easy one to be caught at.

-maybe you should pressurize the frame with NOS, and just vent it near the airbox, or any number of ways to introduce it.

We've talked about this one. Too easy to catch. They look damn closely. Tech can take well over an hour.

after all of that tuning, like motorcycle racing, the driver will still win it or lose it. maybe you should recruit a 50lb 8 year old from the local kart track.


That's so true it isn't even funny. One of the british teams is lead by a PhD student who works for BAR Honda, and their driver is a british karting champion. The rules require anyone involved to be a student at school. That's all. A good driver and a well tuned car make far more of a difference than an optimized design. It's one of the flaws of the competition. Fuck designing the car right, just get it done 3 months before competition and you are pretty much garanteed like top 20 (out of 150).


if you want something radically different, how about leaving the engine revving at a constant 10k, and work on a traction control system based on an external clutch ? after all, that's where the HP exists, not at 5k.

You mean a CVT. Nothing new there, plenty of teams use them.
 
Re: hmm, a fluid storage sump....

Cygnus said:
So how can we suck air through the restrictor at maximum velocity all the time, not just when the engine is screaming?

You're close, but you want a small turbo, not a big one. A big turbo builds more boost, but takes higher rpm to drive. You use a small turbo that makes a completely driveable engine, and widens up the torque curve. It doesn't matter how hard that huge turbo is pulling once you hit the restrictor (about 10-11k rpm), so you want to use a turbo that makes the engine hit the restrictor as soon as possible.


Obviously, there's some physical limit to how fast the air can pass through that restrictor (let's say 300 mph),
Yep. Its when the airflow goes supersonic, and develops incompressible shockwaves.

(e.g., in the previously mentioned giant airbox), under pressure, like an Airsump?
Yeah, except your throttle is above that giant airbox. You close the throttle, and there is still a whole bunch of air to run through your engine before it responds. Air box size vs throttle response is a pretty big compromise- see the bottom of this post

(I'm thinking 5-7 psi).
It doesn't exactly take a big turbo to make 5-7 psi. Cmon, Evo's make 21 psi stock.

You were on the right track with the big airbox idea, but you missed the reason why. For an NA motor, it doesn't actually pull air at steady state. It pulses. The effect of those pulses arn't too bad on the 4cyl, but lots of teams use dirtbike singles. The bigger the plenum, the more air it has in reserve. This way, the restrictor doesn't get maxed out instantaneously every time a cylinder goes through the intake stroke. It actually pulls more air all the time, and you get more top end out of the engine. However, throttle response is huge, and its well worth giving up a hp or 2 in order to have a driveable engine.
 
And about priming the accusump. This may be true, but we don't have it.

You guys are suggesting all sorts of light exhausts. Come on, the whole reason we ride bikes is because the level of engineering and performance is so much higher than on cars. How is a car exhaust going to be any lighter than a carbon Yosh slipon? The max noise level is at a pretty damn perfect number. You can get a normal aftermarket exhaust to pass, but if you just throw it on without spending some time thinking about it, you might be suprised.

As for designing a custom exhaust to resonate at the noise test rpm- Yep, lots of people do it. You're talking resources though. That is one kid who is now dedicated to designing an exhaust, rather than helping build the critical parts of the car. The number one fucking commodity on an fsae team is man-hours.

Speaking of which, hurry up and design that shit Miran- Our car is about 90% done with design, and the chasis is about 40% complete at this point. All we need to do is finish up the diff mounts, and integrate those with the rear suspension to finish all car design. Then its BUILD BUILD BUILD and we are still shitting ourselves about how far behind schedule we are. So get crankin!
 
<<-it seems that if you have to use a restrictor, you should restrict the throttle bodies too, to provide a uniform flow.
Why? Once the airflow is restricted, you can do whatever the fuck you want and it won't make a difference (other than hurt you). They purposely leave the door wide open, in order to make us figure out the optimal solution. You can run a huge assed throttle body, but then you lose throttle resolution. There is an optimum range.>>

it would seem that the throttle bodies should match the restricter size so as to maintain port velocity and laminar air flow. unless i'm misinterpreting where the restricter is placed.



<<-vacuum the crankcase is supposed to be good for at least +1HP
Very true. They make us run a crankcase overflow thingy, so you have to fab a pressureized container. We have one.>>

why ? wouldn't the crankcase overflow bottle just be at the output of the vacuum pump ?


<<if you want something radically different, how about leaving the engine revving at a constant 10k, and work on a traction control system based on an external clutch ? after all, that's where the HP exists, not at 5k.
You mean a CVT. Nothing new there, plenty of teams use them.>>

well, that's sort of what i mean, but those systems don't actually leave the RPM at max. you still control the system via the throttle.
do you have a link to the system the teams use ?
 
PantyBuncher said:

it would seem that the throttle bodies should match the restricter size so as to maintain port velocity and laminar air flow. unless i'm misinterpreting where the restricter is placed.

The throttle body (we only have 1) is placed upstream of the restrictor. That means that there is the entire intake plenum and runners before the air hits the engine.



<<-vacuum the crankcase is supposed to be good for at least +1HP
Very true. They make us run a crankcase overflow thingy, so you have to fab a pressureized container. We have one.>>

why ? wouldn't the crankcase overflow bottle just be at the output of the vacuum pump ?


You use the PAIR valve. You wern't actually thinking about adding a vacuum pump to the car for 1hp? Jesus, spending an extra day or two on the dyno will yield more benefit than figuring out how to hook up a vacuum system to the crankcase. Weight = gold. Time = gold. Its hard enough to build a car that can successfully run for like half an hour straight, let alone spending umpteen billion hours on crazy schemes to tweak the car that last 2%. There are more cars than not that will run for the first time within a week of the competition. There are teams at competition rebuilding engines in their hotel room because they blew it up tuning on the dyno that the organizers provide for like half a day before comp. There are teams that finish welding tubes to the chassis at comp. It's that bad.

<<if you want something radically different, how about leaving the engine revving at a constant 10k, and work on a traction control system based on an external clutch ? after all, that's where the HP exists, not at 5k.
You mean a CVT. Nothing new there, plenty of teams use them.>>

well, that's sort of what i mean, but those systems don't actually leave the RPM at max. you still control the system via the throttle.
do you have a link to the system the teams use ?


No, because any system that a team uses will not be off the shelf. Not too many teams do it, because bike engines have transmissions already. Teams that run alternate engines tend to ues the CVT, like Briggs and Stratton, or very expensive custom motors. I'll link all the competition pictures I can find, and you can see if you can find a picture for youself.

EDIT- this first link is hosted by a CVT/Briggs team. A couple pics there.
http://evilallianceracing.com/ipw-web/gallery/FSAE05
http://dot.etec.wwu.edu/fsae/HostedPics/2005_Detroit/index.htm
http://dot.etec.wwu.edu/fsae/HostedPics/2005_Detroit_2/index.htm
http://dot.etec.wwu.edu/fsae/HostedPics/2005_Detroit_3/index.htm
http://dot.etec.wwu.edu/fsae/HostedPics/2005_Detroit_4/images/images/index.htm
http://stoopidsavant.com/v-web/gallery/0505fsae

There's about 1500 pics, and that's just 2005. There's another set from 04, if you want some of them too.
 
Originally posted by xtasie99
I have to say, you're one hell of a seat of the pants dyno.
Originally posted by xtasie99 When the heck did I say temp doesn't matter to an IC engine? I didn't extrapolate horsepower figures- I showed a difference in pressure.
My apologies. I thought you were merely mocking someone and snidely saying "Despite your real world experience, I'm here to tell you what you felt could not possibly be real, or it is so insignificant that there's no reasonable way you could've measured it! Why, the perceived change in power delivery must've been due to a fart trapped between your asscheeks and the seat!"

You can decide for yourself how many hp 0.028psi of boost makes, or whether that increase needs an intercooler, or if the gravity due to the moon effects the color of your blinker fluid.

My blinker fluid is intercooled, motherfucker.

I examined the effect of the velocity of the air on static pressure. I compared this pressure with the static pressure at STP. I could have plugged in a temp of 238472395465 degrees on both the static pressure and the dynamic pressure and it would have given me the exact same answer. A change of 0.028psi.
No, what you did was examine the effect of velocity of the air on static pressure.

All is well and good until you use your data to make an invalid logical claim, namely that because the static pressure undergoes a gain so infinitesimal, nothing else could account for a noticeable gain in power that should not have been noticed in the first place.

Kevin Cameron's Sportbike Performance Handbook
Rad-looking scoops sell bikes, but forward-facing intakes have one real purpose at less-than-race speeds. That is to prevent hot air from radiator, cooling fins, or hot exhaust pipes from entering the carburetors. Air loses density as it is heated, so hot air gives less power than cool air. Forward-facing airbox intakes exclude all hot air. Another thing they do is to point intake noise in the opposite direction to exhaust noise. This is as useful in meeting noise standards as the time-honored trick of putting one exhaust pipe on each side of the bike-- the noise meter can only be in one place at a time.
 
Well sure, but I was talking about a racecar application, where regardless of ram air or not, the intake is out in open air where there is no temp difference.

And had it been anyone else but Skippy, I probably would have been mocking them. But I'm not about to tell him he can't feel half a horsepower, or the difference in throttle response. He has a hell of a lot more experience than I do.
 
PantyBuncher said:
-it seems that if you have to use a restrictor, you should restrict the throttle bodies too, to provide a uniform flow.

xtasie99 said:
Why? Once the airflow is restricted, you can do whatever the fuck you want and it won't make a difference (other than hurt you). They purposely leave the door wide open, in order to make us figure out the optimal solution. You can run a huge assed throttle body, but then you lose throttle resolution. There is an optimum range.

Originally posted by PantyBuncher
it would seem that the throttle bodies should match the restricter size so as to maintain port velocity and laminar air flow. unless i'm misinterpreting where the restricter is placed.

Hold up. You've got an engine that normally pulls air through a forward-facing intake ("Ram air") into a resonating tuned airbox, then through a four 38mm (or 40mm on later models?) throttle bodies, into ports designed for that airflow. And with appropriately sized (big) valves.

Now on this competition machine you're pulling air through a single throttle body and a single 20mm wide restriction... with stock ports and valves sized for the original machine. And to complicate things, these valves may have overlapping intake timing, since intake and exhaust valves are occasionally open at the same time for that mm mmm scavenging effect or whatever you want to call it.

Physics is not my strong suite, so lemme try and understand here: the 20mm restrictor could be considered a venturi effect, I assume. The air must gain velocity and drop pressure. What happens when the reverse happens, after gaining velocity, dropping pressure, and getting dumped into a tract that has a volume substantially bigger than the restrictor? Everything I have read (and admittedly, its merely book knowledge and not real world) points to ports changing as gradually as possible, rather than sudden changes that introduce turbulance where you don't want it.

I may be ignorant, but it sounds like a really mismatched air pump system-- like the time my boss related how pain-stakingly tuned bigger valves/ports ended up making less power than the smaller original valves/ports, despite bigger displacement and lighter engine internals.
 
Well, you're getting to the limit of my engine knowledge.

http://evilallianceracing.com/ipw-web/gallery/FSAE05/IMG_1638
Look at the order, starting with the filter. Throttle->restrictor->plenum->runners->engine

So yes, going from the restrictor to the plenum is doing exactly that. But that's how you design a restricted system. It's very different from a non restricted one.

And yes, these engines are not optimized for restricted running. Some teams do all sorts of cam work and etc etc. My team, we run pretty much stock engine with remapped fuel/ign.
 
Webberstyle said:
From the rulebook:... a single circular restrictor must be placed in the intake system between the throttle and the engine... Thus, the only sequence allowed is throttle, restrictor, compressor, engine...
well, that kills the "suck it through at 100 mph all the time" plan. but it makes me wonder how you moved the throttle(s) from its original location to this outboard location.
 
Back
Top