The Cal-look Lounge

Cal-look/High Performance => Pure racing => Topic started by: SMO on May 02, 2007, 23:21:45 pm



Title: Straight cut cam gear or OEM for my new engine ?
Post by: SMO on May 02, 2007, 23:21:45 pm
I´m building a 2332cc engine, and have one thing left to buy, cam gear.
Some people said that OEM cam gear is ok and other say go for straight cut cam gears.
Need some help from you.

Engine spec.
CB Engine case 9,5mm deck
Cyl Kit, 94 x 82mm
84mm CB Super race crank, chevy journal.
5,7" Scat rods
Eagle Racing cam 314 degree @ .050" 260° / Lift @ cam .411" or 13,04mm @ 1,25:1
1,25:1 Scat rockers.
Lightweight Lifters
Street Eliminator 2000 heads with 44*37mm

Max RPM at engine 6500-7000 r/pm

Please give me some good advice
And does any one of you tryed this cam CB nr 2246?

/Magnus




Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: nicolas on May 03, 2007, 06:52:56 am
why build a very big engine and not have straight cutgears?  i would run them and they make a very nice zooming sound that you will miss for shure if you have ever heard it before.

 ;D

plus they add hories to the engine (les friction = more power)


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Jordy/DVK on May 03, 2007, 11:27:01 am

 Straight-cuts do not add an axial force to your crank-&camshaft, which is better for your bearings. Especially when your going to increase forces on your valvetrain by running higher RPM's, higher lifts and using stiffer springs. The added HP and whine is a nice +...


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: SMO on May 03, 2007, 11:50:31 am
Yes..and same question.. why build  2332cc when you can build 2387cc ?  my answer to that is. i´m satisfied with 2332cc. It´s a daily driver and less noice is better. But i will not compromice the durability of the engine. And the few extra HP , dont care.
Wounder what´s the best for a daily driver.

And if i must have straight cut cam gears, what do you recomend. Brand and material.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Frank LUX on May 03, 2007, 12:13:36 pm
Yes..and same question.. why build  2332cc when you can build 2387cc ?  my answer to that is. i´m satisfied with 2332cc. It´s a daily driver and less noice is better. But i will not compromice the durability of the engine. And the few extra HP , dont care.
Wounder what´s the best for a daily driver.

And if i must have straight cut cam gears, what do you recomend. Brand and material.


Sounds to me like you already made your decision on the Cam Gear...

If you are to use Straight Cut Cam Gears use the Steel/Steel onces from Magnum...

Frank


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: SteveW on May 03, 2007, 15:22:32 pm
The CE (Competition Engineering) cam gears are also very very good!


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Zach Gomulka on May 03, 2007, 16:17:01 pm
Yes..and same question.. why build  2332cc when you can build 2387cc ? 

Increasing the stroke will lessen the cross section that the main journals and rod journals share, weakening the crankshaft. Also, smaller stroke engines are narrower (closer to stock) so the sheetmetal fits nicely with no gaps, and the pushrods are shorter (lighter and will deflect less... slightly more valve lift). When you go past 82mm it is also advisable to increase rod length so your pistons dont hit the crankshaft and so you have an acceptable rod ratio. Increasing rod length increases the width of the motor even more, not to mention the extra weight of a longer rod. Not to mention the extra clearancing to the case and camshaft that is necessary with extra long strokes.
In my opinion, a 2276 is a perfect engine. Use short and light 5.325" H-beam rods on an 82 chevy journal crank, that gives you a very nice 1.649:1 rod ratio, a stout crank, and an engine that ends up slightly narrower than a stock 1600 with a pump gas friendly compression ratio around 9:1.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: SilverPig on May 04, 2007, 06:39:07 am
Don't mean to piss on anyone's feelings here, but if straight cut gears were that great, why weren't they stock? Just because of the sound? And what about the gears in a gearbox? Should they be straight cut as well? I understand that straight cut gears have less friction and therefore give more ponies, and they make that cool sound, but since the friction area is smaller, the gears will wear out sooner.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Zach Gomulka on May 04, 2007, 07:28:11 am
I imagine it was because of the noise. Ever heard straight cut gears in a gearbox?? They SCREAM!


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: SilverPig on May 04, 2007, 07:43:54 am
Hmmm...something like reverse?


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Zach Gomulka on May 04, 2007, 08:03:32 am
Hmmm...something like reverse?

Kindof, but imagine it at 6,000 rpm ;)


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Jordy/DVK on May 04, 2007, 11:02:51 am

 A split window bug has straight cut 1st and 2nd gears. You can hear them very well. They make considerably more noise.
 And yes straight cuts wear out a little sooner, but isn't that what a performance engine does in general...


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: folkevogn on May 04, 2007, 11:09:43 am
But it takes energy to create sound so that means that loose some power aswell  ;)


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Jon on May 04, 2007, 13:44:14 pm
Straight cuts is needed when high spring pressure is needed. When and if you need high spring pressure is another debate.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Harry/FDK on May 04, 2007, 16:57:47 pm
It doesn't take energy to create sound, i spend numerous nights on Paul Ricard Raceway during motorcycle Endurance races, and the Kawa's were always having that great straight cut sound from their engines and were winning. If it would take energy they wouldn't go that way. Most winning Endurance racing cars use straight cuts werever thay can, just to save on "sideload" and eating energy. My humble opinion. Have a good Wkend.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: folkevogn on May 04, 2007, 18:58:00 pm
It think it takes energy to make sound, but not very mutch. so my opinion is that regular camgears will loose more power than straight cut ones, but they too will also loose some.It was kind of a joke about the loss off power because its probably a piss in the ocean when it comes to the total power output. so i agree with all the opinions about the use of straight cut gears, I wouldn`t use anything else myself. And what a beautiful sound it is!!!


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: nicolas on May 04, 2007, 20:02:29 pm
It doesn't take energy to create sound, i spend numerous nights on Paul Ricard Raceway during motorcycle Endurance races, and the Kawa's were always having that great straight cut sound from their engines and were winning. If it would take energy they wouldn't go that way. Most winning Endurance racing cars use straight cuts werever thay can, just to save on "sideload" and eating energy. My humble opinion. Have a good Wkend.

see always listen to a man who has spend much of his time on such a nice track. never raced any track in my life, but PRR is avery nice place and a bit surreal if you look around it. and yes there is the thing about the sideload as well. and i have heard different straightcutgears. not all make a LOT of noise. mine is quite quiet. it has to do with how tight the gears fit into eachother.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: besserwisser on May 05, 2007, 20:11:31 pm
There is a nice compromise for the straight cut gears. Put a 30horse kit in it,they have a another angle on the cam gear and take the other gear of a 30horse crank. They are also extreemly light since some are made out of pure magnesium.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: SMO on May 06, 2007, 22:18:10 pm
30 hp gears sounds interesting :) have a old engine somewhere in the garage. Will take a look at them.
But i think i´ll buy straight cut cam gears for my engine just in case.

I´ll agre, the noice is very nice ! but on longer trips and daily driving could be to much :) but i´ll have to live with that.

Looking on CB´s page and Cip1.com and they have some straight cut cam gear kits, I´m going to order from cip1
this week and wounder if some of theirs kit are ok ? Prices from $60 to $120 for Bug Pack.
Some advice ?

Have anyone tryed CB´s cam with part nr 2246 ? On one dyno chart (CB´s web site) they use this cam on a 2180cc engine
They put out 165 hp @5500r/pm and max torque 157,56 Lbs at same RPM (5500).

I´m looking for an high torque engine, I´ll try to use Dual Dellorto DRLA 40mm with 36mm venturis on this 2332cc as a test.
If it´s possible i´ll hope that the engine deliver max HP with this cam at 6500 RPM, and with 6500 RPM i hope i have the highest possible air speed
in my dells. My brother in law runs a very nice 2332 with comp eliminator heads and IDA 48mm and 37mm venturis. Very nice race engine.
So i hope that this will work.

Have someone tryed Dual DRLA 40 mm on a 2332c engine ? or do you think it´s wasted of time ?



 




Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Harry/FDK on May 08, 2007, 20:43:03 pm
Nicolas, i just gave my HUMBLE opinion. Sorry about that...And excuse me for breathing.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Jordy/DVK on May 08, 2007, 21:36:15 pm
 Hurry.. read Nicolas' message again... he's doesn't say anything mean... I think you kind of misunderstood his message... ;)


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: nicolas on May 08, 2007, 21:41:45 pm
Nicolas, i just gave my HUMBLE opinion. Sorry about that...And excuse me for breathing.

hey

i wasn't bashing on you or being sarcastic i was just saying Paul Ricard circuit is a very nice place. no intention to step on any toes. we all have our ideas and that is why we share them here. i sure don't say mine is the best or anything. sorry to have upset you

you have my permision to breath => that is sarcasm  ;D ;D ;D

regards

nicolas


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: nicolas on May 08, 2007, 21:43:26 pm
Hurry.. read Nicolas' message again... he's doesn't say anything mean... I think you kind of misunderstood his message... ;)

indeed i didn't mean anthing bad.  ;)


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Harry/FDK on May 09, 2007, 11:02:13 am
Sorry, I completely misunderstood you. I will now continue to breathe. :o Thanks.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: nicolas on May 09, 2007, 16:29:54 pm
Sorry, I completely misunderstood you. I will now continue to breathe. :o Thanks.

no problem  ;)


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: SMO on May 10, 2007, 21:16:35 pm
Just recived a straight cut cam gear from CB performance. Hope it´s good stuff for the money.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Harry/FDK on May 10, 2007, 22:32:23 pm
Did you check the article (1745  engine)  in Hot VW's ? They file the edges off of the gear corners to make it a little quiter.. I can have it too loud...


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Jordy/DVK on May 11, 2007, 00:51:16 am
Just recived a straight cut cam gear from CB performance. Hope it´s good stuff for the money.

 They're said to be quiet...


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Diederick/DVK on May 11, 2007, 01:21:33 am
Yup, from what i understood CB is the best (as in most quiet and good performance anyhow)


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Jon on May 11, 2007, 11:41:07 am
How accurate and how noisy they become is up to the machining of you engine case. VW and Empi made different gears for different occurring spacing between cam and crank.... nowadays this option is gone. So its now just down to luck.

Check out this box from Empi, thirteen different sizes... talk about a quality product...  today one size fits all...
(http://cal-look.no/lounge/index.php?action=dlattach;topic=418.0;attach=1594;image)


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: SMO on May 11, 2007, 13:23:50 pm
Yes..and same question.. why build  2332cc when you can build 2387cc ? 

Increasing the stroke will lessen the cross section that the main journals and rod journals share, weakening the crankshaft. Also, smaller stroke engines are narrower (closer to stock) so the sheetmetal fits nicely with no gaps, and the pushrods are shorter (lighter and will deflect less... slightly more valve lift). When you go past 82mm it is also advisable to increase rod length so your pistons dont hit the crankshaft and so you have an acceptable rod ratio. Increasing rod length increases the width of the motor even more, not to mention the extra weight of a longer rod. Not to mention the extra clearancing to the case and camshaft that is necessary with extra long strokes.
In my opinion, a 2276 is a perfect engine. Use short and light 5.325" H-beam rods on an 82 chevy journal crank, that gives you a very nice 1.649:1 rod ratio, a stout crank, and an engine that ends up slightly narrower than a stock 1600 with a pump gas friendly compression ratio around 9:1.

Yes 2276 is a very nice engine. 84mm stroke and 5,7" rods will give me a rod ratio 1,723:1 which is also good, You should have rod ratio around 1,7. Long rods give you a better angel when the pistons are in BDC. And long rods give you more torque, less side power on rods and crank.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Zach Gomulka on May 11, 2007, 16:51:56 pm
Yes 2276 is a very nice engine. 84mm stroke and 5,7" rods will give me a rod ratio 1,723:1 which is also good, You should have rod ratio around 1,7. Long rods give you a better angel when the pistons are in BDC. And long rods give you more torque, less side power on rods and crank.

Agree to disagree ;)

How accurate and how noisy they become is up to the machining of you engine case. VW and Empi made different gears for different occurring spacing between cam and crank.... nowadays this option is gone. So its now just down to luck.

Check out this box from Empi, thirteen different sizes... talk about a quality product...  today one size fits all...
(http://cal-look.no/lounge/index.php?action=dlattach;topic=418.0;attach=1594;image)

I dont think that is a straight cut gear. Helicut gears need all the different sizes, just like stock.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Jon on May 11, 2007, 23:08:31 pm
I dont think that is a straight cut gear. Helicut gears need all the different sizes, just like stock.

No, Its not a straight cut gear, but this illustrates a point. There are several  different measurement between the crank and the cam. From what little I learnt at school about designing gears, I can't remember a straight-cut gear to be considered a universal fit.  What I´m trying to get across is that the fit doesn't come with the brand, it comes with your case.


Title: Re: Straight cut cam gear or OEM for my new engine ?
Post by: Jordy/DVK on May 11, 2007, 23:33:23 pm
Yes 2276 is a very nice engine. 84mm stroke and 5,7" rods will give me a rod ratio 1,723:1 which is also good, You should have rod ratio around 1,7. Long rods give you a better angel when the pistons are in BDC. And long rods give you more torque, less side power on rods and crank.

 More important!!! Long rods don't make the piston accellerate as much as short rods do. Long rods make the piston accellerate and brake more smoothly.
 Faster accelleration (also more mass: therefore use the lightest as possible of everything) greatly increases the stresses and strains on bearings and rods and it consumes power.
 Especially when you're running high RPM's... The longer the rods, the smoother the accellerations inside, the smaller the internal forces, the more useful HP out of your engine...