supertrapp exhaust and cooling on F4i engine

[Cygnus]

Re: Tom the smartass

I dunno. I was just being a smartass.

I know why you're here, you're looking for ways to make your kart faster!

 

[elskipador]

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.

don't worry you weren't the only 1. the guys @ my shop didn't believe me either until i got 2 of them to ride it with the air scoop removed 1 day and the air scoop replaced the next. i still think it was more of a throttle response thing than an all out hp thing @ least @ lower speeds. kinda like the PAIR mod, small gain but a gain none the less.

 

[Cygnus]

Re: Re: hmm, a fluid storage sump....

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...
I think you missed my point. the point was to have a massive amount of energy stored in the spinning turbo before the start of the race, and use that stored power to pressurize the airbox (regardless of engine speed), not have the engine try to spin up the turbo during the race. but now that I know about the upstream throttle, it's moot.
It doesn't exactly take a big turbo to make 5-7 psi. Cmon, Evo's make 21 psi stock.
I chose 5-7 psi for two reasons: it's the most I think you can boost an already high compression engine, and it's the most I think you can count on a half-stock/half-home-built intake tract to contain. Yes, I'm fully aware that many engines that were designed to be turbo engines are running over 20 psi right off the showroom floor, but I'd be surprised if you could boost a 600 that much without custom pistons and cams

 

[xtasie99]

That would be a MASSIVE amount of energy stored in that turbo. This isn't a drag race, its a roadrace. The huge assed turbo's gyro effects would have more effect than anything else I think

You have a good understanding of the boost levels. I'm not an engine guy, but I've read that most teams start at the 5-7 range, and after lowering the CR with pistons and running E85 they will get up to 15-18.

The cars arn't half assed by any means. Carbon monocoques, carbon wheels, Ti chassis', custom designed/built shocks, transmissions, brake calipers, magnesium stuff etc. One team designed and built a V8 engine. And that's just mechanical. There is also custom ECU's, custom electropneumatic or electric shifters, traction control, launch control, data aquisition + telemetry, electronic boost control... So I would hope that we could weld together an intake that could take 20psi.

As for moving the throttle body- you throw away the stock ones, and get a large single one mounted at the end of your intake. Or, since we use the stock fuel rail for a variety of reasons, we pull all the throttle parts out of the bodies but leave them attached.

 

[xtasie99]

Elskipador, you ever gonna go get a job at Yosh? Our alumni there quit, so we're having trouble mantaining the sponsorship. We need someone on the inside

 

[elskipador]

As for moving the throttle body- you throw away the stock ones, and get a large single one mounted at the end of your intake.

why in the world would you want to do that???

Elskipador, you ever gonna go get a job at Yosh? Our alumni there quit, so we're having trouble mantaining the sponsorship. We need someone on the inside

hopefully by the end of next season.......hopefully.

 

[Eisernkreuz]

why in the world would you want to do that???

Because of the rules:

"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."

So filter->throttle->restrictor->engine

 

[xtasie99]

Miran, don't waste your time trying to make a shroud on the far side of the radiator from the fan like you were talking about. Inlet shape is important in jets, not radiators with little plastic fans on them. You have much better things to spend your time on.

 

[Eisernkreuz]

bump

I have no updates. I haven't done shit yet but read Compact Heat Exchangers, and I have to say, I am totally lost. Wish I'd taken thermodynamics already

 

[elskipador]

Because of the rules:

"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."

So filter->throttle->restrictor->engine

well that sucks!! i'd rather use 4 20mm restrictors and get to keep the individual throttle body per cylinder ratio. stupid rules.....

 

[morthrane]

Because of the rules:

"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."

So filter->throttle->restrictor->engine

So, the air provided by the turbocharger goes straight into the intake *after* the restrictor? Huh. Doesn't that kinda defeat the purpose of a restrictor?

well that sucks!! i'd rather use 4 20mm restrictors and get to keep the individual throttle body per cylinder ratio. stupid rules.....

No kidding. Getting even fuel flow to each cylinder must be a nightmare.

Given the weird rules, I bet ya some kind of Honda v4 variant would work nicely.

 

[xtasie99]

http://dot.etec.wwu.edu/fsae/HostedPics/2005_Detroit_3/pages/DSC00388.htm


Fuel flow per cylinder isn't an issue. You can put the injectors where ever you want. My team leaves the stock throttle body/fuel rail on, but pulls out the butterfly valves so they are just straight tubes with the fuel rail bolted on.

Air flow per cylinder is an issue, but no more than it is any time you are designing an intake with a single throttle body.

 

[morthrane]

Fuel flow per cylinder isn't an issue. You can put the injectors where ever you want. My team leaves the stock throttle body/fuel rail on, but pulls out the butterfly valves so they are just straight tubes with the fuel rail bolted on.

Air flow per cylinder is an issue, but no more than it is any time you are designing an intake with a single throttle body.

Didn't realize the injectors could be 'downstream' of the restrictor... certainly simplifies it a little.

The reason I mentioned the V4... you can probably get nearly equal intake tract lengths as compared to an I4, since the widest point is roughly two cylinders instead of a full bank of four.

 

[xtasie99]

Well the runner length is an issue, so you just need equal length runners up to the plenum. Thats pretty easy to deal with when you're making your own plenum and runners.

 

[Eisernkreuz]

Wee ha, preliminary diagram

 

[Eisernkreuz]

Sucks not having anyone older here in the lab to help me out. Also sucks trying to design a cooling system when you haven't taken thermodynamics, thermo-fluids, or heat transfer yet

So far, I need to calculate the heat load of the engine, determine the cooling specs of the radiator from Visteon, figure out the optimal plenum depth between the rad and fan, and put it all together And I'm sure some more math will crop up between now and then

 

[xtasie99]

Why even make a plenum? You have the the rad and fan in a longg tube. Who needs a shroud when there is a big fiberglass/carbon one all around. Refer to any pic of UTA with their sidepods off.

Just make your sidepod like an inch or so larger than the rad, and then apply an inch or so of foam to the edges of the rad to seal to the sidepod. Then, at the exit of your sidepod, make it bottleneck down to the fan size.

 

[Eisernkreuz]

Making the shroud won't be that much more work or cost or weight, and will make the seal better as well as giving the body guys the freedom to make the sidepods any way they like.

I'm still trying to figure out an ideal plenum depth..some say rule of thumb is 40% of fan height, but I can't put that on paper and give it to the judges

 

[bxr140]

Haven't been following the whole thread, but note that you can't cram a whole sidepod's worth of air through a radiator with the same cross section as the sidepod. In fact, if you have a duct of cross section A, you need a radiator with a cross section about 3-4 times (depending on the actual radiator) that of your duct. Any smaller and you'll start pissing off the aero guys as you'll have too much "backed up" airflow spilling out from the inlet.

Not sure about the "optimal plenum depth". I assume its a result of avoiding excessively dirty flow?

 

[xtasie99]

Yeah Miran, that is a good point. As for a distance, honestly I've never heard anyone actually being asked that by a judge. There is so much going on in these cars that unless you point it out to them, they often won't ask. I got asked all of like 2 questions regarding my wings. 2 questions for one of the most uncommon components of the car which is subject to much speculation and debate. Yet they had a guy to quiz us for 10 minutes on ergonomics...

I made a shroud last year for our chassis dyno cart, and will be doing the same for the car's shroud. I used a chunck of polestyrene foam and a hotwire. Make one profile that is the size of your rad, and another that is the size of your fan. Stick each profile on one side of a foam block of thickness "l"(from your pic) and then hotwire between the two templates. Then wrap the thing in wet layup carbon/glass. When its cured, you can melt out the foam with acetone. It won't be the prettiest shroud, but it will work.