Cams

[Frank]

ok,

spill your guts...

what have you got, and where did you get it..

RIT especially, start talking

regards

Frank http://fsae.com/groupee_common/emoticons/icon_smile.gif

(this is meant to be a joke/giggle, but by all means, feel free to educate us all)

[PatClarke]

Of course Frank.
CAMS is the ASN, the body responsible to the FIA for the management of motorsportin Australia
...And with whom we organise our FSAE-A insurance http://fsae.com/groupee_common/emoticons/icon_smile.gif

Oh, I see, not that sort of 'Cams' http://fsae.com/groupee_common/emoticons/icon_confused.gif

Pat D'Rat =]

Rudeness is a weak mans imitation of strength

[Charlie]

We didn't use aftermarket cams, but we did find a trick to increase performance. By shimming under the tappets, you increase lift the thickness of the shim! We saw big gains on the flowbench with this trick, in fact we saw a big improvement at 0 lift!

You should really try it. Don't worry about clearances, these engines are pretty forgiving. http://fsae.com/groupee_common/emoticons/icon_wink.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Lyn Labahn UW-Madison]

Just cut about 3/4" inch of welding rod off. Tack it with a tig at the top of your lobes. I garuntee 20HP at the wheels, and love from all the ladies.

2002/2003 Team Leader
Best overall average finish of the new millenium http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Daves]

stock stock stock

[gug]

dont know much about the cam profiles of these 600 supersports (gsx600, cbr600 etc.) but i understood then to pretty much be racing engines straight out of the box. is there much to be gained from going to a different cam profile? does the restrictor have any effect on the suitability of the stock cams?

- if it isnt coming, you need a bigger tool.

[Matt Gignac]

These cams are most probably best suited for very high rpms (this is where most bike engines will make peak power), where a lot of our restrictors have already choked the engine. Perhaps a lot of us could benefit from a profile that is better suited for lower rpms

[t-pod]

Interesting subject matter...who is going to be the first to divulge information? I hope nobody took Charlie seriously, running one of these engines to 12,500 rpm without any lash sounds like a great way to turn your engine's piston into an ashtray.

I am curious if anyone has done any extensive dyno testing on the effects of cam timing. Advancing the intake will increase volumetric efficiency at lower average piston speeds. Any experienced engine builder will tell you that's how to make a restricted SBC put out decent power. Does it work on a 600cc motorcycle where the piston speed is much greater? I've seen some testing performed by UMC that indicates no. However, I'm not sure as to the completeness of their testing (nothing against UMC here, they're an awesome team that has done enough dyno testing to run their engine around the globe). Anybody from UMC care to share?

Something else that has always intrigued me is the use of the California cam. You know the one that makes the bike emissions legal in Cali so it doesn't contribute as much to the crap filled sky over LA. It's a milder cam that may be more compatible with the restrictor. Anyone ever compare these two back to back with?


Jon Denton
MSU FSAE

[Frank]

ok time to sound silly.. perhaps

i always thought that

increasing VOL/(decreasing LCA, for a given duration) narrows the torque curve (torque curve being roughly proportional to VE, disregarding "pulse tuning")..... a "skinnier" torque curve resulting

and

increasing duration shifts the power curve to a higher range

and of coarse these beasties use a very early closing exhaust profile to reduce emissions



I'd be trying a get a slightly narrower torque curve at a lower rev range

soo.. with my reasoning i'd guess a regrind leaving more VOL (requiring less LCA) , decreasing the duration, and retarding the exhaust closing point would be the way to go (effectively retarding the exhaust cam a bit)..... increasing the lift would be at the mercy of piston-valve clearance....


as for Charlie's post.. sitting at home i cant even remember what clearance these things run, if any...

from memory they're 8 mm lift (rpm and life consideration) so, say if they run 020" hot clearance, you could possibly get 010" extra without stress.. just guessing that the piston-valve clearance is in the standard 040"- 060" ballpark?.... Charlie, before i go insane... were you serious?

regards all

Frank

[This message was edited by Frank many times] http://fsae.com/groupee_common/emoticons/icon_smile.gif

[This message was edited by Frank on July 22, 2003 at 01:54 PM.]

[Marc Jaxa-Rozen]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Charlie, before i go insane... were you serious?<HR></BLOCKQUOTE>

Anyone claiming flow improvements at 0 lift is hopefully kidding http://fsae.com/groupee_common/emoticons/icon_wink.gif

As you say, increased duration and valve overlap favor high RPM ranges. I'd look at the VOL first, less overlap would definitely favor low-end torque.

Just going from theory here, anyone have the specs for the smog cam?

[woollymoof]

I thought that you want less overlap at high and low RPM with the most at midrange. If you have too much overlap at high RPM you will over scavenge sending new charge up the exhaust port and loose VE.

Cheers,

Kirk Veitch
Swinburne University of Technology

[Charlie]

Haha, no, not serious. http://fsae.com/groupee_common/emoticons/icon_wink.gif

Seriously, I think there are minor gains to non-OEM camshaft profiles because of our shifted RPM range. But it would be a costly and time consuming process to get right. I think teams have done it, I wonder what kind of gains they are seeing. I think it would be a 3rd or 4th iteration before you see benefits worth the time. It's definitely something that makes a good, verified simulation model a nice thing to play with.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Frank]

ahhhh, i thought the "0 lift" was a typo...

http://fsae.com/groupee_common/emoticons/icon_smile.gif

I agree with you totally Charlie, id recon it would be an expensive process..

we all noticed that RIT had the awesome mid- range, and they told us that "comp-cams" supplied them an aftermarket cam..

i rang "comp cams" about this, and everyone there either..

A didn't know anything about it

or

B wasn't going to tell me / supply

regards

Frank

[Kevin Hall]

I measured the F4, and found .042" to .045". I was told that .040" is about all you can go, but I know guys have planed their heads for higher compression successfully, but nobody will divulge any more info that spoken success.

Kevin Hall
University of Saskatchewan
'03-'04 Team Director

[Marc Jaxa-Rozen]

Frank,

Comp Cams mostly specializes in V8 cams, RIT probably had them do a custom grind (which is around ~300 USD for a small block Chevy, but I don't know what kind of cores they carry for our application; it'll be more expensive for sure).

All in all it's probably not worth the price, unless you can devote lots of simulation and testing time to make sure that other areas of your engine development are advanced to a point where you actually need the cams.

Marc
ENA

[MikeWaggoner at UW]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Marc Jaxa-Rozen:
Frank,

don't know what kind of cores they carry for our application; it'll be more expensive for sure).
<HR></BLOCKQUOTE>

You can just use stock cams for blanks. Cam grinders aren't super complex things, and at Western that teacher had rigged one up that seemed to give satisfactory results using a universal grinder and simple attachments he built there. I wouldn't be suprised if someone up there would post a pic of it.

UW FSAE
The views of Mike Waggoner are not necessarily the views of the UW FSAE team.

[terc04]

UMC tells all.

We did do a lot of dyno testing. A good portion was dedicated to exploring the possibilities associated with camshaft timing, specifically on the intake side. Based on many readings we were more convinced of the effect of the intake cam on overall performance rather than the exhaust cam.

We purchased a set of adjustable cam sprockets for our particualar engine of choice. After many hours in the freezing cold wrenching on a burning hot engine we came up with no substantial results. We did see the characteristic changes to the power curve that is normally associated with changing cam timing, but we did not find the holy grail of FSAE engine tuning (consequently that came later with muffler plug I had made prior to competition in anticipation of not passing sound).

One problem we realized shortly after abandoning cam tuning was clogged injectors due to ethanol eating our fuel cell foam and depositing a layer of 'dirt' on the injector screens. After cleaning the screens we found an extra few ponies right where the cams were showing minor gains. With additional tuning we may have been closer to our original goals, had we found the problem sooner.

The biggest reason for abandoning the adjustable cams was the constant maintainance required to keep the cams in time. Over a three hour test session the cams would self adjust up to three degrees out, putting us dangerously close to valve to piston contact.

In the end we had too little time to re-explore the benefits of cam timing. We found many other gains late in the season, most of which would now possibly benefit from further investigation in cam timing.

Tim Roberts
University of Missouri - Columbia