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Old 10-10-2009, 04:58 PM   #31
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So, what differentiates off-road and on-road motors? Component dimensions?
longer stroke, different timeing, thinner blocks, smaller cooling heads...I think.
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Old 10-10-2009, 05:08 PM   #32
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So, what differentiates off-road and on-road motors? Component dimensions?
Not really.

On/off have shared the same bore/stroke configurations for a while now.

On road will run a larger carb (9mm is commonplace) along with a physically smaller cooling head (since there is so much airflow available; better cooling).

A lot of the difference is simply in port timing/configuration as well as crankshaft induction (more...in general).

Most onroad engines would be best served if you swapped the front bearing out from a shielded to a rubber-sealed unit.

Other than that there isn't a single thing stopping ya from running one.

Another point is that onroad carbs are usually aluminum-bodied in many cases. They're not as forgiving to dirt intrusion (compared to composite) but they CAN be used and inserted according to your needs.

With today's lighter weight buggies, there's not as much weight difference between 1/8 on vs. off any more. One could easily do without the bottom end 'hit'; clutch accordingly and have a strong/broad powerband that would keep revving on a larger track instead of pooping out. On shorter tracks...no, you never really get to see the goodness.
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Old 10-16-2009, 06:45 PM   #33
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Well, there is a big difference coming soon. The latest Nova Collari edition motor features a longer pilot shaft on the crank. This is great for onroad as it will eliminate the spacer/cup/shaft thingy we have to use. I wouldn't be surprised if all onroad motors eventually go to this crank. You would have to put about 15-20mm worth of spacers on the thing to make it work for offroad clutches, assuming the car has the room for it.
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Old 10-16-2009, 09:36 PM   #34
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Most offroad setups just "bolt up" and sit flush with minimal spacers (Jammin'/Ofna; Losi).

And I know the Losi 2.0 Buggy sure doesn't have that much room to go forward with the crank, it almost hits the tank as it is if the chassis really flexes hard.

Sounds like a good idea for onroad...but would def. kill cross-use if they follow through with that concept.
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Old 10-16-2009, 09:55 PM   #35
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Iv heard that the jammin 21/28 have onroad cranks for a smoother feel.
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Old 10-16-2009, 10:31 PM   #36
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If they did that then they failed because that engine hits way to hard.
I stuck an onroad .21 in my revo, should have used a werks adjustable clutch on it.

I stuck a VZRII crank in a Vspec, ran really well. as well as the Vspec cranked VZRII. Allot of people stuck onroad cranks in p5s back in the day as well.
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Old 10-16-2009, 10:56 PM   #37
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What would be a good on-road engine for off-road racing??
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Old 10-16-2009, 11:15 PM   #38
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Mileage-wise; none of them really.

They'll all make more power and lose mileage.

Something like the Novarossi R321PS wouldn't have been tooo crazy on a bigger track (again...change the carb, ft. bearing and cooling head)...might have worked, but kinda cost prohibitive.

The GRP on road/rally was basically just a mildly hotter 7 port of the buggy 5.
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Old 10-17-2009, 08:10 PM   #39
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i heard the p7fms was an on road p/s with off road crank. money wise rb has the classico 9 for $244 on amain so it would be worth a shot, just needs an off road head really. not square stroke like the sport rb's, same bore/stroke as a c6 with a 14.5mm crank. sounds like a winner to me.
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Old 10-17-2009, 10:37 PM   #40
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Quote:
Originally Posted by mblgjr View Post
Mileage-wise; none of them really.

They'll all make more power and lose mileage.

Something like the Novarossi R321PS wouldn't have been tooo crazy on a bigger track (again...change the carb, ft. bearing and cooling head)...might have worked, but kinda cost prohibitive.

The GRP on road/rally was basically just a mildly hotter 7 port of the buggy 5.
So your saying an off-road engine will give better fuel mileage and be about the same power??
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Old 10-17-2009, 10:45 PM   #41
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So your saying an off-road engine will give better fuel mileage and be about the same power??
Nope.

I'm saying when using an on-road; in off-road use. You will make excess power for the given traction conditions and have less fuel mileage.

Most buggy engine make less total power and thusly, get better mileage than on-road specific engines.
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Old 10-17-2009, 10:51 PM   #42
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Originally Posted by j_blaze14 View Post
i heard the p7fms was an on road p/s with off road crank. money wise rb has the classico 9 for $244 on amain so it would be worth a shot, just needs an off road head really. not square stroke like the sport rb's, same bore/stroke as a c6 with a 14.5mm crank. sounds like a winner to me.
Yeah,I was thinking the same,the Novarossi 21-7FMS.I heard it was a hybrid also,the bottom end of a buggy engine and the top end of a on-road engine.

The reason I'm asking is because I'm going to be racing in a big event in the 1/8 "GT" Rally game class and I need an engine that is going to be able to push the buggy base chassis with great effort,but at the same time have unlimited top end.This is of course an on-road racing event with buggy based cars.
So I think the .21's will have the advantage because of better fuel mileage.
But I don't know which .21 would be better suited for this kind of racing.Any suggestion would be helpful.
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Old 10-17-2009, 10:57 PM   #43
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Originally Posted by mblgjr View Post
Nope.

I'm saying when using an on-road; in off-road use. You will make excess power for the given traction conditions and have less fuel mileage.

Most buggy engine make less total power and thusly, get better mileage than on-road specific engines.
O.k. I understand now.On-road engines make more overall power and use more fuel to do it.Where as buggy engines make good power and use less fuel.

I'm trying to find a good .21 engine to use for "GT" rally game racing which needs enough torque(off-road engines),to move the buggy based car.But at the same time have unlimited top end to scream down the straightaways and big sweepers.What would you suggest.
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Old 10-17-2009, 11:08 PM   #44
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I modify offroad engines with a hybrid timing profile between Offroad and Onroad...The end result is an engine that has good low end power but will scream to the moon on the top end.....I can work with pretty much any engine !
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Old 10-17-2009, 11:15 PM   #45
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I modify offroad engines with a hybrid timing profile between Offroad and Onroad...The end result is an engine that has good low end power but will scream to the moon on the top end.....I can work with pretty much any engine !
Maximo,from your experience,what engine would you suugest to start with.
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