First off, a little background, especially for those that don't know Formula SAE rules.

Background:
Formula SAE is a collegiate design competition where students from schools across the country and around the world build small open-wheeled race cars and compete in both static (design related reviews, etc) and dynamic competitions against schools from across the US and around the world. The dynamic testing involves Acceleration (basically a drag race), Skidpad, Autocross (similar to SCCA, but smaller, slower courses) and Endurance (22kms of 1 lane track trying to go as fast as possible and use the least fuel possible). Obviously based on where this is being posted, my question revolves around the engine. We're capped at 610cc, and have to run an intake restrcitor. Our restrictor diameter varies with the fuel we use. We're allowed 3 choices: 93 or 103 octane (20mm diameter restrictor) or E85 (19mm restrictor). Up until this year, our team has run the 600cc Honda sportbike engine off of the CBR600RR, claiming this as the best power and reliability combo. Well, at the "guidance" of the professor in charge of the group, we've started to look at 450cc single cylinder engines, namely the one from the Yamaha YFZ-450, mainly due to weight and packaging of the entire engine/transmission assembly. The engine in stock form saves us around 60lbs, but we're also down ~35hp (last year's 600cc engine made 85hp with the restrictor). To me, the lighter weight is great, but doesn't mean a whole lot unless we can make some of the power back. Now, onto my question.

Question:
Our rules state that the only thing allowed to be in front of our restrictor is our air filter and throttle valve. Any kind of induction or anything must be after the restrictor, which is not a big deal. Rally cars use restrictors before their turbos and they still make good power out of small engines. But, the difference is that their throttle is after the turbo, whereas ours must be before the restrictor and the turbo. This is where I run into a snag. I've spoken with a couple of my buddies who's knowledge of engines (especially turbo'ed engines) I trust, and we've come up with a possible solution. Our idea was to run a solenoid on the compressed side of the turbo (between the turbo and engine) to try and avoid the turbo continuing to build boost when the throttle is closed. The best thing we came up with for not completely closing off the inlet to the turbo was some form of IAC. Since we run a slide throttle, my band-aid fix idea (this would suffice for testing, but may or may not make the final production throttle) was to machine out a small area of the housing to allow air to pass even while the throttle is closed. For engine management, we run a Performance Electronics Edge module, which allows us to adjust ignition and fuel delivery (not sure on the specifics of this computer, so if anyone has any more info on the capabilities of this computer, that would be very helpful). Unfortunately, basically our entire current team is seniors that will be graduating in a month or so, which leaves very little time to get any kind of info from any of them that may know about the computer. Fortunately, PE is local to us, and they are able to help us with anything we can't learn before the Seniors graduate.

I'm sorry for the long post, so I'll add some cliffs. I thank everyone here in advance for any/all help you guys can provide since this is something that's baffling me and this forum comes very highly recommended.

Cliffs:
1. FSAE = 610cc max displacement, forced induction open, 20mm (or 19mm if running E85) intake restrictor before any kind of intake system save the filter and throttle.
2. Changing from Honda 600cc to a Yamaha YFZ-450 engine, either with standalone Performance Electronics Edge module
3. Looking at turbo, but stuck on placement of different parts and what will be needed. Here is the order of how things have to go, by the rules:
Filter - Throttle - Restrictor - cold side of Turbo - Intake - Fuel Injector - engine - exhaust manifold - Hot side of turbo - exhaust
Obviously other components are going to be needed, any suggestions on this?

Factory engine specs:
Type:2004-2005 439cc, 2006-2011 449cc, 4-Stroke Single, Liquid Cooled w/ Fan, Titanium 5-Valve DOHC
Bore: x Stroke 95 mm x 63.4mm
Compression Ratio: 11.4:1
Fuel Delivery'”2004-2008 Carburetion: Keihin 39 mm FCR w/ Throttle Position Sensor,

Again, thanks in advance for any/all help
-Matt

 

Vacuum on a turbo can be bad if you don't get a carbon compressor seal , vac. Will draw oil out of a dynamic seal turbo. Finding a small carbon seal unit might be difficult.
Ihi rhb3 sounds about the right size.

 

question: How will you adjust the fuel delivery with the edge when you have a carburetor? Are you dithcing the carb idea?

Another question: Why do you assume the turbo will continue to try to spool when you close the throttle? VW's run draw thru setups all the time and as far as I know thats not an issue. Like lance said though, you'll need the carbon seal.

Some ideas: You guys are engineering students so I assume you have some competent machinists within the group. Could you A) knock down some of the factory cam profile a bit to bring the powerband into the more useable RPM range of a 19-20mm inlet? In N/A or turbo form, that inlet will be maxed out long before that motor will be in the power band of the cams B) Seperate the cams a bit with an adjustable timing set to open up the lsa? These two things combined with 11+ compression and e85 would make quite a peppy little motor in my opinion. Also what is the budget on this project?

 

Also if your budget allows, Aerocharger makes a very compact, lightweight, Variable Vane, self contained oiling turbo charger. I'm unsure whether it can be ran in draw thru form. They do have sizes that are quite suitable for small engines in that deisplcaement range as their main clients seem to be side by sides and ATV's. Just a thought

 

I'm sorry, I forgot to mention, we're running fuel injection. We start with the carb'ed engine (cheaper), then change it over to fuel injection. I knew there were a few things I forgot in my post, so if there's something else, just ask and I'll do my best to answer.

As for the turbo continuing to spool when we close the throttle, the engine is still spinning, forcing air through the hot side of the the turbo. Will it be making a ton of boost? Probably not. But I would imagine any kind of suction on the back of the throttle plate is going to be very bad for either the turbo or something else in the system, if somehow the turbo can take the abuse. If we don't need the extra complexity of several solenoids, that's good news. Would the carbon seal completely alleviate the problem of the still spinning turbo trying to pull against a closed throttle plate?

Thanks for the ideas on the cams. I'd never thought of that, but now that you mention it, that's a very good point. I'll definitely keep that in mind. I just found a set of adjustable cam gears, so that should help a lot with adjustability.

As for the budget, I have a feeling it will be as bare-bones as possible, seeing as cost of the entire car is a factor in the competition. Most likely this setup wouldn't be on our car until 2013. I have a feeling that people aren't going to want to tackle more projects next season (we're making a lot of changes to the car, now that the rules may/will open up a little bit with regard to chassis and wheel size). Hopefully, when we go to competition, they (the people that run the financial part of the team) see that the car is way underpowered and will allow us to spend some more money on the engine development. If for whatever reason, I'm given the green light for 2012, then that would be nice. Again, no set budget at this time, but the cheaper things are, the better, since cost if part of our competition.

Can you guys recommend any more turbos to look at? I've gotten the recommendation for this Garrett: http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT12/GT1241_756068__1.htm on more than one occasion from guys that race atv's. When I used one of the calculators I found on here, we can get pretty close to the 76% efficiency curve, but unfortunately, that doesn't account for the restrictor.

I just looked at the Aerocharger, and that is very interesting. I like the idea of a variable vein turbo. That would definitely help to fix basically any turbo lag issues we may have. Thank you very much for that suggestion. Do you have any idea on the cost of the Aerocharger? I saw their kits aren't exactly cheap, but look to have everything one would need. Unfortunately, much of the kit looks to be designed for each application, which means it will pretty much be useless for us. But I guess that's what the machine shop is for...

Thanks again guys, and I look forward to a couple of more responses now that I think I've given you guys all the info.

 

Send an email to someone at IHI. They gave us a very small turbo to use on our FSAE car at SIU-Carbondale for free.99


I don't see a problem with running the turbo post TB, it's been done plenty of times in the past. You have to remember that the turbo is being spun by exhaust energy and not by engine RPM. if the throttle is closed, then the turbo is starved for air, and in turn cannot produce positive pressure. This will mean that the exhaust energy will be very low as weill and will not be able to spin the turbo with any appreciable amount of force. Thus, your thoughts of the turbo spinning after throttle is shut should not be of concern. The throttle blade is accustomed to being under vacuum, and if you're using an EFI system, then you can design a TB such that it will prevent airflow under closed throttle conditions. If in doubt, you can put a recirc valve in place after the compressor back to the inlet and source the vacuum from just after the TB.

 

I'll definitely look into IHI some more. Free.99 is always nice...

Thank you for putting my mind at ease. It's nice to know we won't really have to worry about a vaccum behind the throttle blade.

 

Are you at the Michigan event?? I'm there on the UNCC team.

 

I could send you some suggestions for small turbos, but they would be in the $600 plus shipping area, and meant for 660cc car enignes.

 

I am new to the board but, I have a couple ideas related to your project.

The first is a big bore or stroker kit for your engine. A quick view shows that you could make it a 534cc engine.
http://www.google.com/#hl=en&source...bi&bav=on.2,or.r_gc.r_pw.&fp=69b1da9d4f1d0d24

I have read a post involving vacuum at the turbo and having the seal problem. In the post the person made an orifice to allow some air to the seal area to relieve the vacuum pressure. I think it bleed to or from the large part of the compressor.

The post was on an engineering forum and the person was doing the "Formula SAE challenge using a parallel twin "I think 650 kawasaki?". There were several pages of reading and he was facing many challenges. The post over a year or two ago so, I don't remember much more.

Good luck,
Mark

 

Yes, I was at the Michigan event from Thursday through Saturday, as a spectator with the UC team. Congrats to you guys on finishing endurance. The UC car got pulled off for leaking oil during the driver change.

I was at the Michigan event trying to learn as much as I could, and thankfully did. There were a lot of cool (fast) cars there, and some that gave myself and a couple other of our younger (non-senior) team members some good ideas and directions that we're going to be shooting for next year. I especially liked the Wisconsin car. 325lbs, turbo single, space frame, 10" wheels. We pretty well decided that's going to be our direction to head towards. Just a matter of getting data logging on some of our old cars and getting them up and driving to use to try and get more team members for next year...

Ocshaman, please post up any/all info you've got. If you don't want to post it, feel free to PM me. The more info I have, the better decision I can make.

Busa, If we want to bore/stroke the 450, we can go up to 585cc. Unfortunately, that would cost us like $10k just to get the engine up and running. Do you have a link to the other thread you were reading?

 

I could not find the thread I was reading about the twin cylinder turbo but, I may have found the person involved. The time frame is right and the pictures look like what I was reading about. Here is the PDF link, if you search for more by the authors you may get more results.

http://www.google.com/url?sa=t&sour...sg=AFQjCNGSa6xP3eFp5c45UG36OgT1zFr3Yw&cad=rja

Here is the google search I used to look for it, it is loaded too. http://www.google.com/#q=formula sa...=N&bav=on.2,or.r_gc.r_pw.&fp=69b1da9d4f1d0d24


Also, I spend a lot of time at www.suzukihayabusa.org in the turbo section. The guys there are good on bikes but, this forum is better on pure technical knowledge such as concepts and mechanical workings.

Mark

 

Building a 450 into a 585 is really expensive, like you say around 10grand and most pple only net around 65-70hp. Stock turbo 450s should do 80. A big bore kit would be pretty cheap and pick up a few hp. How about a 350 2stroke Banshee lol

 

A banshee would be awesome but not very reliable... when they run good they are bad ass but then something breaks and you are working on it for hours trying to figure them out... GM built post carb turbos back in the late 70s early 80s with out much problem... I dont think its the ideal setup but it worked.

 

Thanks for the link. That led me to several papers by the guys down at the University of Melbourne. They basically made their own engine (side by side twin, 434cc, IIRC) and then did testing of NA with 13:1 compression vs turbo with 9.5:1, and the turbo smoked it. They didn't take the time to test a lot of ways to lower the chance of detonation, just mentioned that they exist. There's also a decent bit of good info about reaching the maximum flow capabilities of the restrictor.

Turbo5point0, we have to run a 4 stroke. Banshee's a 2 stroke, so that's a no go. As for the big bore, that's something I've been considering. The Melbourne 434 has a 69mm bore and a 58mm stroke. The only reason I'm a bit worried about the big bore is that it's more mass to move, which has me worried about piston speeds and accelerations, with reliability being paramount in this application. If we don't finish the Endurance portion of the event, we're out 40% of our possible points. But you're right about the potential power, it's definitely there. With a good bit of engine tuning on the dyno (the Melbourne study took 2 years) I'd think we would be able to take care of most of the detonation issues, etc.

 

I don't think displacement is necessarily a huge issue in this engine range. I wouldn't worry about strokers. Obviously the 20mm restrictor is going to put a HP cap on any NA combo. Even a boosted app will still see a similar HP cap due to the inlet size.

 

I agree... You may not have much power loss with your restrictor installed on a 450cc motor compared to the 600 you were working with.

 

The boost spike issue when closing the throttle on a drawthrough setup has been dealt with for years, with a BOV. The BOV will dump extra boost from the intake, keeping the compressor from surging. The BOV is boost/vacuum referenced from under the throttle plate, or in your case just after the restrictor. You should be able to find a tiny version of this Tial. http://cgi.ebay.com/ebaymotors/Tial-50mm-QR-BOV-Blow-Off-Valve-QRBOV-Flange-BLUE-1in-_W0QQcmdZViewItemQQhashZitem5adfbcf500QQitemZ390300759296QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Looks like you have already found some info on funneling the max amount of air through the restrictor.

I doubt using a stroker or big bore kit would help make power. Running a smaller displacement with higher boost generally makes more power than extra CCs. As mentioned, changing the cam out to drop your powerband would make a big difference.

 

Not to disagree with you, but there are teams making 90-92hp NA (4 cylinder 600cc engines, reving very high) and some making 107-110 turbo (Cornell made 107 this year at comp, and Colorado State made 110 at the wheels, again both with high reving 4 cylinders). I understand the theory that the restrictor should hit a flow limit as you get to a certain RPM value, but what doesn't make sense is how these teams are still making these numbers reving so high. I agree, there's a point where the restrictor will cut power, but any idea how these teams are getting around it?

Craig6.9diesel, that is our hope. The restrictor cost us a decent bit of power with the RR engine (compared to stock), but it seems to be hurting us less with the 450cc (we have a grad student working on a thesis evaluating the 450 for FSAE use, unfortunately, he's put no time in to optimize the tuning or anything else).

MiniMonster350, that BOV seems ungodly huge for what we need, but I understand the point of posting it. When it comes time to look for BOV's, I feel like there's not going to be many small ones out there. But what you're saying is to put the BOV just after the restrictor, and vent to atmosphere?

The big bore/stroker idea isn't one I'm seriously considering, but the thought had crossed my mind, mainly in terms of trying to displace more air volume to spin a larger turbo. I used one of the calculators on here, and basically every point on Garrett GT1241 compressor map was to the left of the surge line. As I upped the displacement, the points moved to the right of the surge line. Unfortunately I can't seem to find any kind of compressor map for the little IHI turbo. Anyone have any links or anything like that? Just trying to get as much info as I can before I start asking the club for money for this turbo project when a lot of them are against it. They claim turbo lag will be horrible, and the car will be undriveable because of it.

 

From my time working at a Yamaha dealership I have found that stock 450 motors will last a long while if taken care of, where the built motors just dont hold up as well, but I really dont know about a boosted 450 motor. Maybe make a spacer that goes under the cylinder to drop the compression down. If you can make 100 hp on this little motor I am thinkin you will be better off. I am sure it will way less then a 600 motor.
I had a 01 R6 that made 104hp at the wheel and it was mostly stock jetted and a pipe (revving it to like 16,000 RPM). So 100 hp out of a 600 isnt that hard but how does the restrictor work? Is it 1 restictor per cylinder or 1 per carb or 1 for the entire engine?