Turbo 600 without restrictor

[mullenc525]

Hi Guys,

Former SAE type here... I ride a CBR600f4i and I want to turbo it. My goal is to maximize torque; HP goals are modest at about 135 from 105.

I figure I need about 15 lb/min at 1.6 pressure ratio, and I want that to be in the upper right of the compressor map to get excellent driveability out of it correct?

Problem is, I can't find the appropriate turbo. I'd prefer a stock turbo off a car since they are cheap, but thats not a requirement. I find most of the small turbos are designed for much higher pressure ratios than I need.

Any advice?

[mullenc525]

Hi Guys,

Former SAE type here... I ride a CBR600f4i and I want to turbo it. My goal is to maximize torque; HP goals are modest at about 135 from 105.

I figure I need about 15 lb/min at 1.6 pressure ratio, and I want that to be in the upper right of the compressor map to get excellent driveability out of it correct?

Problem is, I can't find the appropriate turbo. I'd prefer a stock turbo off a car since they are cheap, but thats not a requirement. I find most of the small turbos are designed for much higher pressure ratios than I need.

Any advice?

[Boffin]

If your only after 130 HP, it should be able to be done NA.
Our engine builder had his race suzuki 600's putting out that.
It would be a better option since then you don't have the weight of the turbo system.

But I find it odd that a GT12 or 15 is not suitable.

[VFR750R]

You're right that aftermarket turbos are always sized to start working at about 12-14psi. Most people don't bother turbocharging for less than that because for similar money you could get similar output at 5psi just maxing out your NA mods.

Stock VW turbo cars are only in the 150-180HP range and those turbos may be acceptable. A 2000 Turbo Jetta runs 8-9psi boost and makes 150HP.

If you run about 6 psi boost you'll be hitting your 135HP (rear wheel) target. At the turbos designed range of 9psi you'll make close to 160.

You may also want to look at some factory saab turbos, some of those run pretty low boost.

[B Lewis @ PE Engine Management]

Hi mullenc525,

We also have a F4i as a shop bike. If you find an inexpesive turbo that will work and you need a programmable engine management system let me know. We might be able to help each other out. We just finished a "plug and play" version of our new ECU for the F4i that uses all of the stock components and just replaces the stock ECU. It also handles all of the OEM functions like driving the dash.

I would be interested to hear what you find. We have been tossing around the same idea.

Good luck with the project.

[Tieneboost?]

A GT12 would work for your desired "excellent driveability". But like Boffin said 130HP can be obtained with a NA set-up. Why would do you want to use a turbo? Are you planning on dropping the stock compression ratio or keeping it 12:1?

[StephenP.]

I believe the turbo that our team has is a GT 12; we never ended up being able to use it. Love to sell it. Also have a f4i manifold, not sure if it will fit your application, but maybe.

Email me at ssparker @ oakland.edu if you're interested

[mullenc525]

Wow, lots of great offers here.

For engine management I'd planned to use a power commander and stock ecu. This is as similar approach to what I used when I modded my toyota supra using an air fuel computer to compensate the stock ECU's output for higher boost. Not ideal but it works for most other people turbo'ing their bikes.

I'm not sure it would be so easy to get 135 HP naturally aspirated. Remember, this is a 105 (probably closer to 100) hp, highly tuned motor as stock. The GSXRs make over 120 hp as stock. Furthermore, if one could make 135 HP, it would probably not have nearly as broad a torque curve as a motor with a small turbo.

Furthermore, turboing is cheaper than maxing out all the NA mods on this bike, since I can do all the fab work myself. Since the bike runs regular gas stock, I figure I can maintain stock compression at low boost and simply run premium.

Looks to me like GT12s choke at 12.5 lb/min and would be running below max efficiency even at max boost. http://s4wiki.com/wiki/File:GT12compress.jpg

[Kirk Feldkamp]

Having dealt with a lot of turbocharged and supercharged motorcycles since graduating, I would recommend trading up to a 750 or 1000 if you want more juice. Most stock 750's make 135+hp out of the box, and will weigh the same as what you've proposed and be 100% reliable. If you go up to a 1000 and still need more than what it can give you, then you should start thinking about this sort of stuff. You also might want to consider quitting school and riding professionally at that point, because even exceedingly few pro riders can truly ham-fist a well tuned 1000. You're going to spend *FAR* more in time and money doing a project like this than you will just to sell what you have now and get a new bike. It all comes down to whether or not you want to spend time working on a project, or enjoying more time riding.

-Kirk

[VFR750R]

Kirk's being a dream killer, but he is right. A 750 would be much easier to ride and have a wider more usable powerband than even a GT12 boosted 600. ...And you'd be able to ride it tomorrow.

[Kirk Feldkamp]

Haha. Buzz kill, maybe? I'm just suggesting if he dreams, dream BIG. There were some supercharged GSXR 1000's I was involved with for a while that were making 225-250hp (depending on how ballsy the riders thought they wanted to be). They were scary fast to say the least. Past a point, the relatively short wheelbases of the standard sportbike offerings are too short to keep the front end on the ground, and more power just means more wheelies. Most turbo Hayabusas and 1000's have extended swingarms for a good reason.

-Kirk

[Nicky]

I read the entire thread twice when you guys said 130HP on a NA with a F4i not to mention with a restrictor. We have a Garett which we bought sometime back, haven't used it yet cause our plenums designed for NA keep shifting shapes(deforming) even after using 3mm thick sheets to make it. Finally we caste our plenum to a wall thickness of 5mm and with 2.2ltr of a volume. So we don't know if the plenum will hold to a turbo.. Our current readings are 62HP@9500 and 41Nm@8400(F4i,2004).

I've seen a few teams from FSAE-AU-05 not using intercoolers or cool their turbos even. Adding those would just make things expensive. I need opinions on whether these are required for such low powers(<150HP) for we can never get funds for an EGT to measure the temp in the exhaust.

How hot does the intake air get if turbo-ed? Our tubing size on the exhaust keeps varying every year and the calculations never settle in on a tried and tested design. I remember the 1"tubing glowing red after a 5min warm up, while the 1.5" doesn't show any sign of heating up...

How do teams get above 90HP on NA??? You folks talk about maxing out the NA designs. Do variable runners make a difference of over 15HP over the rpm range? I also assume that turbos reduce the need for longer exhaust lengths due to the backpressure they readily offer.

We have plans of installing the turbo on the test rig to check it, but we have to do it by cutting the old plenum(budget cuts), would really help, if we could get some input from this topic. Obviously we don't expect designs or calculations from you, just some guidance. Too many doubts, many days spent googling and talking to the local tuners here, but nothing solid...

Regards,
Nicky

[Adambomb]

Sorry Nicky, there appears to be some confusion. Actually this thread should probably be under "off-topic," it's referring to a bike, not an FSAE engine. So no restrictor, and he's starting out with about 105 hp!

As for how to get over 90 hp NA, I can't personally attest to this, but I'd bet it has something to do with harmonics, and requires more than just a good and well-matched intake and exhaust...

As for turbos on FSAE cars, I tend to be more of a follower of the KISS principles. Turbos are sexy, so a lot of newer teams are drawn to them, but IMO they just aren't worth the weight, complexity, and most importantly higher chance of failure.

~~~~~~~~~~

To the OP, +1 to Kirk's recommendation. Turbo-ing a 600 doesn't make sense when you can buy a 1000, and I don't have any spec sheets handy but I'd bank the 1000 has a good bit of the extra torque you're looking for!

If what you're looking for is a more progressive/less peaky power curve, check out the Buell 1125R. And no, it doesn't have an air-cooled un-balanced Harley-based engine, it's a DOHC water-cooled Rotax twin. The power curve is almost perfectly linear, and the big twin still wraps to something like 11k rpm (and sounds sooooo hot up there). 146 hp, 375 lbs http://fsae.com/groupee_common/emoticons/icon_eek.gif. I got to demo one once, and it ruined the experience I once had riding my '88 Ninja 600R. Couldn't compare to the Buell. Only thing that really sucks about them is they're pricey, and they quit making them http://fsae.com/groupee_common/emoticons/icon_frown.gif.

[RenM]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Nicky:

How do teams get above 90HP on NA??? You folks talk about maxing out the NA designs. Do variable runners make a difference of over 15HP over the rpm range? I also assume that turbos reduce the need for longer exhaust lengths due to the backpressure they readily offer.

</div></BLOCKQUOTE>

The exhaust lengths are not used to create a certain amount of backpressure (we are not dealing with 2 stroke engines here) but to influence the time, the pressure waves need to travel back to the valves. If you tune your cam timings, intake and exhaust runner lengths you can beneficially influence your gas exchange which will lead to more air in the cylinder and thus more power. Thats how you can get 90+hp from a NA-600cc 4 cylinder with restrictor.
Variable intake runners are usefull to get more torque over a wider torque range. But you wont get them working if you dont understand the basic gas exchange of the engine.

and perhaps you should rethink the shape of your plenum if you need walls with a thickness of 5mm.

The diameter of the exhaust runners should not be determined by the fact how fast they get hot, but rather by the fact how much backpressure they create. You will want a small diameter to increase the pressure amplitudes and to decrease weight but a large diameter for smaller backpressure. You will need to find a compromise for this. At first you should stick with the stock sizes.