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Diff. between .21 and .28

Old 10-27-2006, 09:24 PM
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AznBash3r
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Default Diff. between .21 and .28

Yes, forgive my dumb and noobish question, but I never found out why people run .21 and they like it better than .28... isn't .28 suppossed to be "faster" and give out more displacement? My guess is that .28 has lots of torque and good top end, but .21 has more of a comperssion ratio (just spittin words out) and gives out more power?
Old 10-27-2006, 09:44 PM
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satoch
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Default RE: Diff. between .21 and .28

I assume you're referring to the use of a .21 in a truggy over a .28. Anything over a .21 is not legal in a buggy for any class but "sportsman" at club level.

The reason is very simple. Fuel economy. When you get to the upper levels of truggy racing winning comes down to missing a jump, a bad marshall, or a fuel stop. If I can run a 15 minute main and only pit once because I'm running a RB Concepts C6BB .21 with their 2045 header/pipe combo and get 9 mins on a 150 ml tank then I only need to pit once. While the guy running a cheap .28 engine can only get 6 1/2 mins and needs to pit twice. That 10 second pit stop may be the difference between winning and losing.
Old 10-27-2006, 10:09 PM
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montrealer
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Default RE: Diff. between .21 and .28

There about a .07 difference...
Old 10-27-2006, 11:09 PM
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Default RE: Diff. between .21 and .28

Being this is the buggy thread I am guessing he is talking about buggies correct me if I am wrong. One of the main reasons is most if not all sanction racing the limit is .21 on buggies. You would be surprised how much less the fuel consumption is on the .21 over bigger engines. On a 7 or 8 pound buggy a good .21 is all you need.
Old 10-28-2006, 12:47 AM
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satoch
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Default RE: Diff. between .21 and .28

aznbash, come to Leisure Hours in Joliet, IL. and race indoor nitro with us on Sundays. You'll learn a lot more there than on line. Check it out www.leisurehoursraceway.com
Old 10-28-2006, 05:17 AM
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axisrc
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Default RE: Diff. between .21 and .28

i was thinking about getting a .32 sure fire for my duratrax axis then should i not get it then is it going to burn a lot of fuel. but when u gun it it sucks up more air than fuel right. and what kind of diff. oil would i want to get on it would it mess up everything of my diffs.
thanks
mike
Old 10-28-2006, 07:12 AM
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sexyfingaz
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Default RE: Diff. between .21 and .28

in my opinon .21's have more bottom end power for fast take off's, most 1/8 tracks are usally reasonably tight so bottom end power is needed more than top end.
big block's (.28,.30 etc) are good for open tracks with fast straights but lack bottom end power and are also illegal except for sportsman and unlimited classes.
Old 10-28-2006, 09:49 AM
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Super_Dave
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Default RE: Diff. between .21 and .28

ORIGINAL: sexyfingaz

in my opinon .21's have more bottom end power for fast take off's, most 1/8 tracks are usally reasonably tight so bottom end power is needed more than top end.
big block's (.28,.30 etc) are good for open tracks with fast straights but lack bottom end power and are also illegal except for sportsman and unlimited classes.
That depends all on porting and timing. The .28s pretty much just give you more torque because of the displacement. I don't think you can run the same kind of RPMs with a .28 then a .21 because of the size of your internals either. If you have a buggy go with the .21... it doesn't need the torque of a .28 and you'll benifit from the RPMs and fuel consumption. If you have a truggy go with the .28 because you'll need the torque.
Old 10-28-2006, 10:43 AM
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David D
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Default RE: Diff. between .21 and .28

It also has to do with the fact that until recently when truggies got popular most engine companies were focusing there technology on .21's since that was the only race legal big block. This made the engines better than the big blocks that were floating around. Now the big blocks are catching up, but the .21's are still faster in a buggy as that is what they are designed around.
Old 10-28-2006, 11:07 AM
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Default RE: Diff. between .21 and .28


ORIGINAL: Super_Dave

ORIGINAL: sexyfingaz

in my opinon .21's have more bottom end power for fast take off's, most 1/8 tracks are usally reasonably tight so bottom end power is needed more than top end.
big block's (.28,.30 etc) are good for open tracks with fast straights but lack bottom end power and are also illegal except for sportsman and unlimited classes.
That depends all on porting and timing. The .28s pretty much just give you more torque because of the displacement. I don't think you can run the same kind of RPMs with a .28 then a .21 because of the size of your internals either. If you have a buggy go with the .21... it doesn't need the torque of a .28 and you'll benifit from the RPMs and fuel consumption. If you have a truggy go with the .28 because you'll need the torque.

Ohh yes they can get the same rpm, they are just not ported for it like you said.
Old 10-28-2006, 11:55 AM
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Default RE: Diff. between .21 and .28

The reason is because the maximum legal displacement is
.21 ci, a .28 built to the same standards as a .21 should be
faster.
Old 10-28-2006, 01:28 PM
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46u
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Default RE: Diff. between .21 and .28

ORIGINAL: axisrc

i was thinking about getting a .32 sure fire for my duratrax axis then should i not get it then is it going to burn a lot of fuel. but when u gun it it sucks up more air than fuel right. and what kind of diff. oil would i want to get on it would it mess up everything of my diffs.
thanks
mike
Wonder how well the Duratrax will hold up?
Old 10-28-2006, 01:39 PM
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satoch
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Default RE: Diff. between .21 and .28

axisrc, I wouldn't suggest a Surefire .32. It's just not a very good motor. Believe it or not, but a lot of the top racers around Chicago who have the RBs and Novarossi engines have a healthy respect for the Sportwerks .26v2. If you're looking for a powerhouse motor that won't kill your wallet that's the motor. Another is the SH ProSpec .28. I run that and it's amazing for the money.
Old 10-28-2006, 06:30 PM
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Default RE: Diff. between .21 and .28

ORIGINAL: satoch

axisrc, I wouldn't suggest a Surefire .32. It's just not a very good motor. Believe it or not, but a lot of the top racers around Chicago who have the RBs and Novarossi engines have a healthy respect for the Sportwerks .26v2. If you're looking for a powerhouse motor that won't kill your wallet that's the motor. Another is the SH ProSpec .28. I run that and it's amazing for the money.
I love my sportwerks engines . Without a doubt they get you the best power for your money and they are very cheap to rebuild. I had a decent edge over a Novarossi P5 down the straight away with my Sportwerks .21 with just about the same low end power. The difference is the Nova will last 10+ U.S. gallons while my sportwerks will only last about 6. However a new piston and sleeve is only $50 for the sportwerks.
Old 10-28-2006, 07:58 PM
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Default RE: Diff. between .21 and .28

Doesn’t SH make the Sportswerks? I think so and SH makes good engiens.
Old 10-29-2006, 03:05 AM
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Default RE: Diff. between .21 and .28

thanks i will look on it today
Old 10-29-2006, 03:14 AM
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axisrc
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Default RE: Diff. between .21 and .28

which powerhouse engine dam that sh engine anit that much might get it
Old 10-29-2006, 03:19 AM
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axisrc
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Default RE: Diff. between .21 and .28

where should i buy it from ebay says buy it now for $130
Old 10-29-2006, 03:32 AM
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axisrc
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Default RE: Diff. between .21 and .28

also does any of those engine take a lot of gas. should i get a new gas tank it has to fit in the duratrax axis with no problems. like some kind of tank that will be good for that engine bigger tank.
thanks
mike
Old 10-29-2006, 08:47 AM
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Super_Dave
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Default RE: Diff. between .21 and .28

http://www.amainhobbies.com/product_...oducts_id/7458
$125 This one has a pull start if you need one without the pull start then try here:
http://www.horizonhobby.com/Search/D...twerks&CatId=E

You don't need a bigger fuel tank for bashing. The .26 doesn't take that much more fuel then a .21 but when your racing you need all that you can get.
Old 10-30-2006, 01:30 PM
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Default RE: Diff. between .21 and .28

Sanctioning rules a side. There are 2 reasons companies put larger than .21 in buggy kits in my opinion.

1.) Bigger sells if someone off the street walked into a hobby shop and saw to RTR buggies for about the same price one with a .21 and one with .28 they would most likely buy the one with the bigger motor.

2.) Entry level .28 are cheaper to make and will have better performance than a cheap entry level .21. It cost almost nothing in material and tooling to add .07cm to a sleeve and piston to fit in a .21 block. It cost a lot more money to tool a production run to manufacture a performance level .21 ( percision porting , timing, crank shaft, etc)
Old 10-30-2006, 01:46 PM
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microengine
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Default RE: Diff. between .21 and .28

quote; "the Nova will last 10+ U.S. gallons"

Do nova, or rb for that matter, make an engine which will last longer than this?!
Old 10-30-2006, 04:01 PM
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Default RE: Diff. between .21 and .28

ORIGINAL: microengine

quote; "the Nova will last 10+ U.S. gallons"

Do nova, or rb for that matter, make an engine which will last longer than this?!
Honestly I don't have any personal experiece with them . Every person I've talked to with one has had them last about 10 gallons. It mainly depends on how you treat the engine to get the life span out of it. You could probably make one last only 5 gallons or less if you didn't run it correctly.
Old 11-02-2006, 08:04 PM
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AznBash3r
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Default RE: Diff. between .21 and .28

Well, I have a turmoil buggy converted to a truggy. Should I stick with .28? how about .32? [>:]

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