CCs vs compression, which works best

Jeff Williams · 09-24-2005, 12:42 AM

Hi all,
well winter is coming on and since I've decided not to ride in Dec anymore,(long story, short answer), I've been looking at ways to make brad Z. ***** at me,(I can here him now...."ya cann't use all power now, why would ya want more?"

).
So I've been researching things and have heard this comment over and over, " their is no subsitute for CC."
Well I've been thinking it over and have come to the conclusion that thats not necessary the case.
Their is a displacemnet where an engine will run better than if it is bigger or smaller.
I've also found that boosting the compression helps more than adding a little more displacement.
I'ld love to here what the group has to say on this.

Here are the options.

assume: big valves, porting, and a cam.

1. High compression pistons in a 1100cc engine using aftermarket pistons
2. 1150 or 1200 cc engine
3. long rod High compression engine using stock pistons,(has anyone done one of these engines?)

BTW, I've heard that their have been problems with the longevity of aftermarket High compression pistons.

I know their is a lot of data that can be thrown at this and their are some that don't feel the need to do things like this,but this is neat stuff and I would appreciate some input form the gear head of the group.
thanks again
jeff

ps just got back from taking my nephew on a little trip. He enjoyed it.

shovelstrokeed · 09-24-2005, 05:12 AM

Ah, near and dear to my heart.

The question is a bit too general for an easy answer though. The first thing needing clarifcation is what are you goals for the bike when done.
Torque Monster? Top End King? Drag Racer?

Most folks want something that will accelerate like a drag bike but are not willing to put up with the peaky torque curve. Ditto the torque monster that falls flat on its nose as the revs go past 6500.

IMHO, the limiting factor for this motor is not its displacement nor is it the cams/compression thing. It is the cylinder head. The head itself is not terrible, although the combustion chamber shape lends itself to some pinging. What sucks (or fails to) is the port routing. The need to effectively package the motor in the frame and keep the riders socks from becoming the air cleaner and the exhaust from becoming nerf bars has more or less ruined any chance of these motors making a heck of a lot more power than they do. I'd be surprised if Byron Hynes could get 135 RWHP out of the donkey motor.

So, back to our bike. Oooo, 1200 cc, long rod, 13:1 compression, lumpy cams, piped, air boxed monster motor. Will generate more heat than its cooling system can shed if used as it is supposed to be. That equates to BANG or seize.

Mild increase in compression, J&E custom pistons, some porting by someone who really understands port shape and a set of cams speced by someone who has worked on this motor before and you might have something that makes about 10 more HP with a nice, fat mid range that allows it to pull like SuperDonkey out of the corners.

Leave it all alone and just bore the silly thing till the fins threaten to look like a stack of washers. Back to the cylinder heads and maybe even more so the combustion chamber. Beware this one as it comes down from the 2nd gear wheelie as the motor runs out of breath at 6K. Displacement helps not at all unless you can feed it.

Option 2 would be mine. The cam thing could get expensive as it might take a couple of sets and a lot of timing experimentation to get things right. The higher compression can be tamed a bit by playing with lobe center timing but, with these bikes, since you only have one cam, that means a new grind (and 2 new cams) for each experiment.

Might be best just to by a 12GS and put the 1100S body work on the thing. But what do I know?

Crunch · Crunch's Garage

What about the 1150cc upgrade kit from San Jose? Has anybody tried that??

roger albert · 09-24-2005, 06:30 AM

The higher CCs will give you more power everywhere.
Cams won't. The higher CCs also give you more compression, by definition.

The heads are a separate issue, but on them, Ed has nailed it.

Given the head limitations, its goofy to consider focusing on tons more peak power (cams) Better for a bit more displacement that helps everywhere, any condition, any rpm, any throttle position, any load.

Deans BMW · 09-24-2005, 07:35 AM

If you want the best no BS answer call Chris at San Jose BMW, he has done it all many times over very sucessfully.

Steve Carlton · 09-24-2005, 08:17 AM

Chris calls Jeff "that crazy dentist in southern California." I think Jeff needs to be the beta-tester for one of Chris' superchargers!

Moybin · 09-24-2005, 08:29 AM

I'll toss one more grenade into the mix:

The higher compression goes, the higher the octane requirements. You need to factor in the availability of suitable fuel, too.

If you are trying to maintain the semi-all-purpose composition of the S I would seriously consider the suggestion to insert an R12GS engine. I'm guessing there would be a lot of frame modification to get it right.

bradzdotcom · bradzdotcom's Garage

i think you should leave that damn thing alone.
maybe get mo-betta brakes.
go do 3 or 4 track days with it. let it romp. make it happy.

why spend $1800 (or more) to get an engine that's smaller and probably slower, than the one coming on the newer bike? is it so you can say "it's fast for an old 1100"???

i still subscribe to the kenny roberts system:
go in deeper, come out harder.

(a riding method which often works for bikes and women!).

here's my suggestion:
since you live so close to some great twisty roads, go get something that is almost too much fun to ride, and it will teach/show you how to ride even faster/better on your beemer.

i've been lusting over one of these for a while now. limited edition '05 husky 510 Supermoto...4-stroke single with electric start, lights and all that crap.
you can get a CA license plate for it.
it's about 7k out the door, about 8.5k when properly set-up for ego-slaying:

more info at: http://www.husqvarnausa.com/2005/05_SM510R.html

added bonus: you can truthfully say "Heidi dear, the engine is only half as big as my bmw. So obviously I...ummm....will only be able to go half as fast."

Dbltailexit · 09-24-2005, 08:48 AM

See Jeff, we just think you need a short fast wheelie machine. That's two opinions that think you should go romp on my Duke 2 an older version of Bradzdotcom Husky. Someone needs to go wear off the sides of the fresh tires. Try it - you'll like it.

Steve Carlton · 09-24-2005, 08:51 AM

Isn't Jeff backing away from the street heroics? Sounds like he just wants to bury us in the straights...

Hey Brad... my mom drives a Husqvarna. (When she's making a dress).

Jeff Williams · 09-24-2005, 10:25 AM

Ed,
sorry about being general.
What I'm looking for is an increase in HP, moving the power and touque curves up without it looking like it went thru an earthquake.
I realize that the heads and valve train are a limiting factor.
A little work could help some but a redisigned head would be better,(good luck on that one

).
I was thinking on not going the 1200 cc long rod but an 1100 cc long rod.
I was talking to chris in SJBMW last week and he said that he has had a couple of J&E pistons break at the skirt within 10K miles.
I'm not a big fan to putting cams alone into this bike w/o increasing compression and head/valve work. It wouldn't give the bike the bang for the buck thats needed.

The R1200S as a substitute maybe as a platform to start from.
I've talked with people who have ridden the test bikes within the last 30 days.
They say that even though the suspension will be better,(Stock1200 vs stock 1100), it won't be better than a properly setup aftermarket suspension. The engine will be stronger than the stock 1100 but isn't stronger than a pipe/chip/aircleaner mod setup.
What do you think about a long rod 1100?
cya

Roger,
I've got to realize I need to be more precise with you.
This is your field and generalizations won't work,sorry

I was looking at a higher domed piston to increase the compression without increasing the CCs.
Could BMW, because of constraints within the head, try to increase the hp by going to the larger displacement 1200?
What did Eron do for pistons and rods, do you remember?
cya

Steve,
ya Chris and I talk alot and yes I would love to try the supercharged bike,(good luck getting that one). I'm still not convenced about 50cc helping all that much. A better piston IMO would be better. The "crazy dentist in southern California", is more than likely right. I got to be crazy to hang out with you and Jeff and Acid.

Call you soon

Moybin,
I'm not worried about pinging as of yet.
The bike doesn't do it and their are ways around it.
But do you have to say grenade so close to this thread

.
Now I'm going to keep thinking," gee Moybin said grenade, what did he mean by that...... I better look at my bike.....why did he say that...... am I going mental?

Thanks Moybin, now I cann't sleep

, cann't eat

, I need a vacation

.
Alright Moybin, thanks for talking me into a vacation, your alright.

cya
jeff

Chris Canning · 09-24-2005, 10:58 AM

Blimey Jeff now you've started somthing!!!! was only talking to Lloyd last week about how you would carry two sets of 1150 barrels with you at Christmas!!!!

Thought the customs/security would have a heart attack when they saw them on the scanner!!!

John,yes that John!! as always said to me a head job on a beemer(S) was a waste of money,their the best production heads he's seen,know of two people that have tried cams and ended up with a bike with a power band!!! and thats not what i want.

Surely there is someone on this board with a SJ big bore kit?? have thought about the BBP route but your going end up with something fragile,and i still exspect mine to take me(us) to Le-Mans every year.

Chris

roger albert · 09-24-2005, 11:01 AM

> 1200 will be stronger than the stock 1100 but isn't stronger than a pipe/chip/aircleaner mod setup.

I doubt that. Those mods tend to make, on the 11S, no more than 5hp on the dyno, and certainly not more than 10 on the open road, most signifcantly less. The current R12 hexhead motors already match or beat that; mostly beat. The 12S will therefore, even if no stronger than the other 12s, very very likely beat the typically mod'd 11 you describe. Probably by a fair amount. Moreso if the new 12S is stronger than the other 12s.

Also, I'm not sure why you think 50cc wouldnt help much, but a simple bump in compression (a mild one at that) would,
Again, the displacement bump automatically yields a compression bump to.

Give the breathing limitations on the upper rpm reaches of our motor, the old 'no-replacment-for-displacement' saw is more accurate than usual even. Again, if you look at the total power under the curve, you'll do at least as well with the bigger motor.

Don't remember Eron's setup, so he'd have to chime in there.
He did about as well as I think is possible with stock displ.
But remember, he got his 12-15 horse with pistons, AND headwork, AND dualplug, AND pipe, AND PC, etc etc.

So, on the one hand, you're right. 50cc will only net you a little.
Otoh, that's true of everything else you can do too, and most of them will do even less, especially in the bottom 3/4 of the rev range

Chris Canning · 09-24-2005, 11:32 AM

Roger

Motor v motor your right,but neither Jeffs,mine,Lloyds are dragging around stock wheels and all the other stuff,50cc on it's own is hardly going to set the world on fire,my Ti wheel spindle isn't either but it's the sum of the total,thats the object of the exercise.

Haveing spent more on the bike than what i paid for it!!,i have people ask about cost etc,it's bit like asking why do people go and climb Everest?? because they can!!!

Chris

Steve Carlton · 09-24-2005, 12:48 PM

Jeff,

You might want to consider keeping your powder dry until the details on the R12S are out. If it's in the 120hp range and lighter, you might be hard pressed to match that hp/weight ratio. The cost of ownership would probably be less by putting your stolen filling money into the new one instead of never getting it back on your old one.

BTW, I get dibs on the old one when you sell it, okay?

JonyRR · 09-24-2005, 02:36 PM

Jeff; no sarcasim intended here... but you're probably semi-bucks-up being a dentist and all.
Go visit the surly genius at RBRacing (Shovel can vouch for his bona fides and I take his opinions very seriously...he knows how to make some serious go-fast motors) and be the first on the block to do a complete-package turbocharger setup on an 1100S. It'll be everything you've ever wanted, everywhere you want it (and probably as spendy as that husky supermoto)...or go buy a service CR500 honda, scam a plate for it and then make a super'tard out of it and smoke 'em all with a 'little 500 2-stroke'...and STILL spend as much as the turbo setup or the husky supermots..hehehe. serious power costs serious money....kawasaki ZX14, anyone?
RB claims power increases in the range of 40-70 HP for an 1100S with their complete package and I don't doubt it....if I had the money, to burn, it's what I'D do

remember, 'injection is nice but I'd rather be blown'....and budget for a decent clutch to hold all that new 'powah!!!

Jeff Williams · 09-24-2005, 03:27 PM

Brad,
thanks for the info on the husky might be fun. We'll see where this takes up.
cya soon

Ingmar,
ok ok lets see what the beast will do. Maybe Wednesday when edilweiss comes thru.
cya

Steve,
Just looking in the corner for the 'G' spot,

and you cann't have my bike but you can have another bottle of wine.

Chris,
didn't know you two wankers needed a set of jugs

so your thinking about the big bore eh.
Well it doen't get hot enough to overheat where you live and besides you two will need a little 'extra' help when Gus gets his 'Rat' bike on the road.
cya in a few months.

Roger,
well said.

Jony,
no sarcarism taken, being 'bucks up' doesn't apply when you have a teenager and one in college. But its nice of you to say that you smooth talker you.

Turbos on bikes have never interested me, superchargers have.
I guess my problem is that I don't want a fleet of bikes, just two or three.
BTW I agree with you I'ld rather be blown.

cya one and all
jeff

Bigred455 · 09-24-2005, 03:45 PM

Quote:

Originally posted by Jeff Williams

3. long rod High compression engine using stock pistons,(has anyone done one of these engines?)

Jeff, I am not the most knowledgeable about R11S internal hardware specifically, but I do know a thing or two about engines.

You asked about a Long rod stock piston 1100cc engine, the only way that will happen is if you shorten the stroke. I think you mean to increase the compression, but that won't happen by just using a longer rod. Increasing or decresing the rod just changes where the piston rides up and down in the bore, and would (depending on rod length) make the piston kiss the head. The benefits of longer rods are less piston sideloading into the cylinder wall. Thus cutting down piston to cylinder friction, which might help the motor run cooler if anything at our power levels.

Onto the heads, does anyone have a set of flow numbers for a stock R11S head? How different are the 1100 heads from an 1150 or are they not even remotely close to interchangeable?

What about even shortening the stroke, incresing the bore and then turbo'ing.... Lots of work for a funky ole donkey bike. Sounds like fun though

Moybin · 09-24-2005, 05:22 PM

Bigred455

To properly apply a turbo the compression of the base engine would actually have to be reduced. Otherwise the existing hardware could be subjected to stresses beyond the design limits of the materials. You want to build a diesel S or what? I think we would find that the engineers have kept the engine's compression within a band of acceptable stresses. That's not to say that we end-users might not find more stress acceptable. But these engines are all about compromise when it comes to design and tuning. Cruiser engines probably drag race better than drag engines cruise, and so on.

Sometimes I just find it remarkable that the internal combustion engine works at all.

roger albert · 09-24-2005, 05:26 PM

> 50cc on it's own is hardly going to set the world on fire

Agreed. Nor will any of the other things Jeff mentions.
BUT, a displacement and attendent/automatic compression bump together, WILL at least yield more than the compression bump alone. The compression bump alone is normally only chosen because it's dirt cheap (pistons, and maybe rings, only) No cylinder exchange, or boring, or other machining. Only reason to go that way in most cases.