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Old 09-02-2008, 09:59 AM   #1
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Default v-spec vs jpx.21 engine comparison

I wanted to get some feedback regarding these 2. Anyone ever owned and raced both of these. How does the jammin compare to the v-spec? Power, fuel efficiency, tune, longevity? thanks guys.
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Old 09-02-2008, 04:30 PM   #2
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The Jammin seems to make more overall power especially at the top end and is more explosive and less linear than the Vspec. I expect the Jammin (actually a Picco) p/s and rod to outlast the Vspec. Plan on replacing the rear bearing on either engine at some point before the p/s is worn out.

You will need to seal the Jammin carb up to get the best results. The Vspec you can just run. Vspec also gets 8-9 minutes run time and the Jammin gets maybe 7:30.

Some Vspecs have had trouble breaking crankcases. That is extremely unlikely with a Picco based engine because of how they mold their crankcases.

I run the Jammin at club races and anytime run time is not important. At big races I run the Vspec if I am going to be running in 15, 30, or 45 minute mains.
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Old 09-02-2008, 04:38 PM   #3
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I have both, and I hate my V-spec. Love my Jammin! Jammin makes same if not more power. was $100 cheeper, and did not leak from every orifice like the V-spec. The V-spec needed a complete rebuild, and reseal, as it had air leaks everywhere. The front bearing sucks air, leaks, and is a piece of Chit. Fuel consumption can be moderated with the right venturi on your Jammin. Go with the Jammin. V-spec sucks.................air!!
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Old 09-02-2008, 06:11 PM   #4
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I have both, and I hate my V-spec. Love my Jammin! Jammin makes same if not more power. was $100 cheeper, and did not leak from every orifice like the V-spec. The V-spec needed a complete rebuild, and reseal, as it had air leaks everywhere. The front bearing sucks air, leaks, and is a piece of Chit. Fuel consumption can be moderated with the right venturi on your Jammin. Go with the Jammin. V-spec sucks.................air!!
Exactly what he said.
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Old 09-02-2008, 06:20 PM   #5
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I run both & like both.V-spec w/2050 pipe feels very similar to jammin or original p-7 w/jp-3 pipe.V-spec gets 1-2 min more run time.Jammin & pipe ready to go $300-325,V-spec & pipe ready to go $375-425.I dont like the jammin till 3-4 gal go through it & it loosens up then I like it more than v-spec.I put TKO ceramics in both $35,jammin because I had to & v-spec because I was scared not to.Talk to guys at the track & see how many V-specs have blown up under 3 gallons.I only know 1 guy that had problems with jammins but theres probably 7-8 times more V-specs in use right now so thats not really a fair camparison.Both good motors with the right pipe but how much you wanna spend & what color head do you like red or blue? Is 1 pit in a 15 min race with no worrys worth the extra money?

Oh yah my V-spec is real sensative to weather(temp but mostly humidity) & the jammin you can set in practice @ 100 deg F & 50-70% humidity @ noon & it will only be slightly lean(not enough to hang up over jumps) @ 60 deg & 20% humidity during the mains that night.
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Old 09-02-2008, 06:38 PM   #6
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no v-spec! P.O.S.!!!!!! cant say it enough,l dont buy the O.S. its junk!!!!
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Old 09-02-2008, 06:43 PM   #7
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I've been using OS engines for around 15 years. I simply don't understand all the issues that you guys are having. Yes there have been manufacturing issues over time. But, they've been addressed. And Yes, I wish they would last as long as RB. But for tunning, easy, easy, easy. Just throw your temp gun away, and tune by smoke and feeling.
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Old 09-02-2008, 07:01 PM   #8
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whats with all the v-spec hate? I have had both engines. and honestly like both of them as well..stock v-spec with AE pipe was pulling 12 mins of runtime in my RC8, stock jammin with AE or JP4 pipe would get ruffly 9 mins. I am not a throttle maniac which helps with fuel mileage. both engines ran great and smooth. (any engine will run great if tuned correctly). I blew a rod on my picco ruffly a mth ago. and just blew my rod on my v-spec 2 weeks ago. I blame my fuel HAHA easy way outta that one... vspec had ruffly 5 gallons on it and the picco had just over 6 gallons. the reason for crankcase cracks was due to rod slop from the crank pin wearing bue to people not installing a new rod at the 1 gallon mark. o.s has revised the crankcase with more gap so no more cracking. every single engine should be tore down at the gallon mark for a new rod and bearings its just the nature of the beast. if you do this and seal the engines correctly you should have no tuning prbs. engines should run good yadda yadda yadda.. everyone has their own comments on threads like these you will get 100 diff. reviews. best of luck go with what you know and what your local hobby shop carrys
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Old 09-02-2008, 07:56 PM   #9
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i would buy a speed, i hear there is a guy that races at the track you race at that has pretty good deals on speeds
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Old 09-02-2008, 10:30 PM   #10
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Originally Posted by jrwoodchuck View Post
I've been using OS engines for around 15 years. I simply don't understand all the issues that you guys are having. Yes there have been manufacturing issues over time. But, they've been addressed. And Yes, I wish they would last as long as RB. But for tunning, easy, easy, easy. Just throw your temp gun away, and tune by smoke and feeling.
The V-spec is a fantastic engine, its just the poor build quality, and very very bad bearings. If they would just put more care into building the engine, better quality control, better bearings in them they would probably be the best .21 on the planet.
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Old 09-02-2008, 11:17 PM   #11
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Originally Posted by blktransam View Post
whats with all the v-spec hate? I have had both engines. and honestly like both of them as well..stock v-spec with AE pipe was pulling 12 mins of runtime in my RC8, stock jammin with AE or JP4 pipe would get ruffly 9 mins. I am not a throttle maniac which helps with fuel mileage. both engines ran great and smooth. (any engine will run great if tuned correctly). I blew a rod on my picco ruffly a mth ago. and just blew my rod on my v-spec 2 weeks ago. I blame my fuel HAHA easy way outta that one... vspec had ruffly 5 gallons on it and the picco had just over 6 gallons. the reason for crankcase cracks was due to rod slop from the crank pin wearing bue to people not installing a new rod at the 1 gallon mark. o.s has revised the crankcase with more gap so no more cracking. every single engine should be tore down at the gallon mark for a new rod and bearings its just the nature of the beast. if you do this and seal the engines correctly you should have no tuning prbs. engines should run good yadda yadda yadda.. everyone has their own comments on threads like these you will get 100 diff. reviews. best of luck go with what you know and what your local hobby shop carrys

Jesus You rebuild after 1 gallon! My jammin is going on it's 9th gallon, no rebuild. I have a Hyper .21 8 port race that has 12 gallons through it, no rebuild. I never had to replace any of the connecting rods in any of my engines. granted some didn't last as long as others, but If you need to replace the rods after a gallon, your not heating up your sleeve enough during break in. That's causing lots of unneeded stress on ur rods.
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Old 09-02-2008, 11:47 PM   #12
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I like both motors but I prefer the Jammin..... I think the jammin has better snap and pushes a Truggy easier..The Jammins are also very durable, I finally had a fully modified Jammin let go at 9 gallons..the rear bearing got sloppy which led to a broken glowplug coil that chewed up the piston.....but even at 9 gallons the piston/sleeve still had great pinch and compression...and this was a fully timed crazy modified engine that was seeing way more RPM then it was ever intended to...So 9 gallons of hardcore racing is very good, all on stock bearing and rod.....IMO the Jammin .21 is the most underrated race .21 on the market
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Old 09-02-2008, 11:52 PM   #13
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If the Jammin .21 is the most underrated race .21 on the market, then the V-spec would have to be the most overated race .21 on the market.
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Old 09-03-2008, 12:24 AM   #14
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i pulled my last vspec (not the speed version) down before i eva started it and drilled a small hole in the rod it reduced the wear on the rod and crank pin
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Old 09-03-2008, 12:39 AM   #15
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I own 2 Jammin JPX 21 an OS Vspec and a Speed.
I have been running them for a while now.
Both engines is very reliable when it comes to idling and not dies in a race.

The jammin engine is definitely the faster engine. The Vspec has better bottom end and is smoother. Not that the Jammin isnt smooth. I just had one of my jammins pop a rear bearing prematurely. damaged the piston skirts with scratches. I took a chance and replaced the bearing and this engine still runs and has plenty compression. It seems that the jammins maintain good compression throughout it lifespan.

The OS is another story. I had one fail on me at 1 galon. Premature wear on the crank. I must admit its the best powerband I have driven so far. Vpec just has the best powerband for off-road period.

My advice is same as mentioned. Get either one. Run it for a gallon. Chane bearings to TKO ceramics and you should be fine.
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