xanaphyst

My Feedback: (17)

I bit on this one as I was building up a revo roller when I first heard of the new engine. I was going to buy the TM from OS but had to give this new engine a try. I'm on fuel tank #7 and the engine is still very tight. I can't imagine the EZ start is going to get this
thing turned over right now (maybe in a gallon or so) but I don't have an EZ start so that is just my inexperienced opinion.


I'm using a traxxas pullstart on mine but also run the 40mm flywheel so I use an Ofna T-Start box sometimes as well. As you can see there is plenty room at the rear of the engine, A-arms are free and clear.


The backplate is nice but only has 3 holes so there is no 4th bolt when using the pullstart. The rod is nice and thick and the same one used on the 28 engine so no worries there.




The Mount.......a mount comes with the engine and as all mounts go there are a couple things to be aware of. On the outboard side of the mount the front hole is a bit shallow so use your stock engine mounting bolt. The rear hole is tapped all the way through the mount but there isn't a whole bunch of metal there so don't tighten it up too much and strip it out ! You can also see in the picture of the rod above the difference in thickness between the inboard and outboard sides of the mount.


The throttle linkage:.......My throttle linkage hole stripped out very easy. I'm tempted to think it has the wrong threads. I replaced the stock traxxas bolt used for this purpose with a regular bolt/nut and used a short piece of carbon fiber tube as a spacer. A very easy fix and it works great.


Fit and finish......The engine looks great and the color matches the chassis perfectly. It looks like the engine that should come with the Revo. It has a compact profile and does not stick up too much like a lot of other engines. I like the fact that it is light and keeps the CG low as handling is important to me. Here it is in my revo, as you can see the body offers a fair amount of engine protection.



Performance...........I'm still running rich and breaking her in. I used the traxxas break in process and she is still quite tight. The temps have been high and I've had to shut her down a number of times because of it even with the rich running.
I've switched over to 15% airplane fuel that has 20% castor oil and the temps have been getting more and more acceptable each run. I'll switch back to car fuel in a few more tanks more than likely. I'm used to running my OFNA ultra LX2 with
a 28 engine so I wasn't expecting too much out of a 21 engine in a monster truck.......I was quite surprised!!! It would wheelie easy and the spool up of these smaller engines sounds great. I'll have a better report on performance in about
half a gallon. (Edit: The heat problem was from using the B5 Force plug, when I switched over to the good ole' traxxas 3232x the difference was night and day, I've pushed it quite hard now with no temp issues)



Half gallon update: This engine totally rips. I've been impressed with it's performance and it seems to be getting only better with every tank. My original worries about being too tight for the EZ starter are gone for those of you that are going to use one. I run the close ratio gear set and a 14 tooth pinion. The engine seems to like this setup but I admit that I have not tried anything else yet. I put in some long straight runs in a grassy field to see if the temps would rise but she didn't have a problem with it. I can't stress enough that the right plug is vital as the performance was vastly different between the B5 Force and the Traxxas 3232x. I've proven the engine is a performer now in the stock form so from this point I'll
start with the mods, buku clutch, THS 146 pipe (high RPM) , motor saver air filter, turbo head, and back plate cover (eliminate pull start).


Engine Mount Update: Picco has received feedback on the mount and looks like they plan to make changes to the noted items above. I don't have any big issues with the current mount but the improvements would be nice.

Stock Carb settings:

Top needle = 2 turns out from close

Low end = 5.5 turns out from flush

idle gap is 1/16 clearance of venturi

Weight:

Fish scale says my truck with no fuel is 8 lbs, 12 oz. Sounds light compared to some I have heard about on the forums.

Transmission and gearing update: I've switched over to the wide ratio setup that comes stock with the revo. The engine goes through the two gears like nothing on the close ratio setup so I figured I'd put some more load on it. The Picco is handling the wide ratio with no problem. (Update #2)---- had to go to the 15 tooth by 40 spur as I still didn't have enough load on the engine...Engine picks up the load like nothing still and I'm having a hard time keeping the front wheels on the ground. I'm likely going to go to the 38 spur soon to further reduce the ratio but I'm going to try to dial out the wheelies some with the slipper and adjustable buku clutch first.


Wheels and tires:http://www.ebay.com/itm/YOKO-Moster-...item2ecd9805ff

I just changed my wheels/tires over to the ones you see in this link. I'm usually pretty good about support of the traxxas equipment as I find most of their stuff pretty good. BUT...one thing they have that really sucks
is their platinum edition wheels. The rims crack easy and the glue job for the tires must be done by a blind person. The wheels in the link have a larger rim but a lower profile tire. They are win win win all the way
and this is why....the thinner profile tire helps control ballooning, the tread pattern is slightly more aggressive, they are cheap, each wheel has a good glue job, they are a bit smaller than the traxxas wheels which lowers the CG of the Revo just a little more, and each one weights an ounce less which is a total savings of 4 oz. of un-sprung weight !!!! This weight savings also helps on the wear and tear of drive-line equipment. If you don't like black I think they have them in white as well. This is a must buy in my book if your building a good handling "race type-ish" revo.

xanaphyst

My Feedback: (17)

http://kevcoracing.com

I forgot to mention I've been bouncing feedback with Kevin over at kevcoracing.com and he has informed me that there is a backplate and turbo head for this engine but I have yet to receive the part numbers. Warning: do not try the .21 Torque engine backplate as it does not fit. I tried it already and it is a no go as the diameter is too large to fit in the P-Max case. I was hoping it would fit so I could just grind the *** off the end of the crankshaft and the engine case would be stuffed as much as possible.

Turbo head and backplate: (I'll post part numbers when I have them)

xanaphyst

My Feedback: (17)

TRX vs. P-Max

I thought it would only be fair to install a TRX 3.3 on the revo so I would have something to compare the Picco against. I figured this is what most people would be converting from so I thought it would be best. I'd like to point out that I have nothing against the TRX 3.3 as I have run a couple of them in other vehicles. My experience has been that they tune very easy and are not fussy.

Head clearance (squish) : This is easy to measure by removing the glow plug and inserting a soft wire into the cylinder, turn the engine over past TDC then mic the wire.


Exhaust timing: Not quite as easy. stand the engine upside down on a flashlight with glow plug removed as measure degrees of when exhaust opens until it closes while rolling piston past BDC

Crank intake timing: use the degree wheel to determine degrees from opening to closing of the crank intake port in the carb passage. I'm not 100% percent sure this is the correct method of measuring this but it makes sense to me I guess:


Here are the results:

Squish Picco = .0225 TRX = .021
Exhaust Picco = 163 TRX = 155
Intake Picco = 190 TRX = 203

I figure the most important thing to note here is the exhaust timings. Low numbers usually indicate more torque and high numbers usually more HP. Higher exhaust timings respond to tuned pipes better. The numbers indicate that the Picco would have more rpm range but maybe a little less torque and this is pretty much what I found. Don't get me wrong the Picco has good torque but the TRX was only torque and died off in power quick whereas the Picco just keeps on blasting away. A quick adjustment on the Buku clutch could give you more wheelies with the Picco than you want but more on that later.

Bottom Line: The Picco wins hands down but for the price the TRX 3.3 is still a good bash and trash general public consumption. The Picco will give the performance people what they are looking for.

xanaphyst

My Feedback: (17)

Making mods to the P-Max:

When I measured the exhaust timing on the P-Max I was expecting to see about 170. I thought the 163 timing left a little window for some experimenting. With the high RPM tuned pipe from THS I had on hand I figured I could make the pipe really shine
with a little more timing added to the engine. I measured up the piston liner to get the diameters for liner shims and cut them out on my CNC.


All I did then was clean them up a little with some emory paper and they were ready to go. The shims were 2mm. I removed one 2mm HEAD shim and installed one 2mm LINER shim.

I put the engine back together at this point. I was going to switch out the bearings with some ceramic but the factory bearings felt very nice and the crank fit was perfect so best to leave already good alone.
The liner shim with the RPM pipe gave me what looks like will be very good results so far. I had to open up the needles as the engine was now drawing more fuel. I need more evaluation time as it is too cold
to be playing with RC trucks outside for very long and the freezing temps weren't letting the engine warm up very well. More to come but looks very promising on an engine that already looks good.
Update: After a bunch of running today I took the liner shim back out. It made too much bottom end go away and the needles were fussy. The best setup has been the THS pipe with engine in stock form. I guess
those picco engineers have it figured out better than my backyard efforts.


Still to come: Turbo head and back plate, just waiting on the mail. There is also another exhaust experiment coming but more on that later.

lilbrett

Looks great man, thanks for keeping us up to date with your experiences with as well as your opinion on this engine. Where did you get it from? I haven't been able to find it anywhere, except for an ebay seller that won't ship to me.

xanaphyst

My Feedback: (17)

http://kevcoracing.com


I bought mine on ebay but I'm pretty sure you can get one from Kevin at the above info.
You can also try ebay seller superhobby as that is where I got mine. I was lucky enough to get the last one but he may have more coming.

xanaphyst

My Feedback: (17)

Jerry rigged back plate for pullstart delete:

Have you ever noticed that rotostarts and pull starts block some of the intake passages in the crankcase (on the engines I have checked anyway). I figured I could get a little more out of the engine by removing the pullstart and installing a correct backplate setup that doesn't block the intake ports. Here are two pics of what I am talking about. The first pic is a start assist setup and the second for box start only. Notice the 2 extra grooves cut in the box start only rear cover ? Start assist schemes are at the expense of your intake ports (somewhat).




I didn't receive my back plate yet from Kevco Racing so I made my own out of the stock back plate. I removed it from the engine and ditched the pullstart, one way bearing, and shaft. Next I plugged up the shaft hole with a nylon bolt with some high temp silicone. I them ground away the material blocking the intake passages. The first photo shows the installation and the second shows the parts removed that are no longer used.


The performance was improved. Mostly noted was the bottom and mid-range. This is well worth doing if you have a box start. I'm thinking my engine temps came down a little as well but I'm not 100% sure of that yet.



UPDATE:

Here is an easy way to get it done. Use dynamite part number DYN0960. File it down so it is flat. ******NOTE*****...You have to grind the *** off the end of the crankshaft to do this.....so take your engine completely apart
first and grind away...it comes off real easy with a bench grinder.

Here is my jerry rig version next to my "less jerry rigged version"



And now installed, It looks like it is the one that should come with the engine...a perfect fit.

xanaphyst

My Feedback: (17)

Buku clutch install:

I've had the clutch installed for a little while now but never did the update so here it is. First of all it is obvious when looking at it that it is a quality unit. Your getting what you pay for with this one. The Picco tore apart the traxxas flywheel so this is how it all started.


Here is a look at the Buku

The pins are nice and thick and you can see the adjustment allen screws that push against the springs

one thing that I noticed very early is that the Buku is very heavy (I have the 40mm version) as compared to the 40mm traxxas. The Buku is thicker and made from I'm guessing 6061 aluminum whereas the traxxas seems to be an extrusion aluminum.
The traxxas is also recess cut in the rear whereas the Buku is solid. Here they are for comparison:

I was a bit worried about this heafty weight at first but the picco has proven to have more torque and punch than I ever thought it would so it doesn't even seem to notice.

One important thing to note is that you need to shim out the crankshaft split taper washer before installing the flywheel or it will hit the carb. The buku comes with these shims so no worries. If you use the 30mm
version I doubt you will need any of the shims. I think I used three of the shims which made the flywheel very close to the carb. Be aware that this flywheel shim job will force you to have to file down the crankshaft
nut just a little ...it's a easy thing...here is a pic:


I use a washer behind my e-clip that holds the clutch pinion on because I like the clutch bell to ride real close to the flywheel. If you don't do it like this then you will not have to file as much of the crankshaft nut.




Bottom Line: The new engine is putting out enough power that this clutch is justified. It is very easy to adjust and can be done in about 15 seconds. I was totally surprised at how much you can change the way the
vehicle acts by adjusting the spring tensions. I did find one thing that is not a plus...this clutch acts like it has a warm up period of a few minutes. Only the first run of a bash session so no big deal. A very small price for very nice
performance. Don't go off adjusting stuff until you have given it a little time. This clutch is worth the money and it will be hard to go back to a non-adjusting clutch after this experience.


update:

More thoughts on the Buku :

I was running my revo in the park yesterday checking out my new 15/40 ratio when it occurred to me why you really don't see racers using the Buku clutch. It's not because it is a bad clutch. I think it is because it offers "too much" adjust-ability. Now your asking yourself...How can this be a bad thing? You see..I adjusted my clutch a little while switching gear ratios. When I got to the park and was testing I started asking myself...How much of this performance improvement is the clutch and how much is the new gear ratio?......AND THEN IT HIT ME....You must have absolute repeat-ability when making performance comparisons. The traditional clutch gives you a choice of three different spring weights....it is easy to get consistent results based on your choice of springs. The Baku depends on you keeping track of how many turns you have on a screw in three different locations...and did you really put that screw back EXACTLY where you had it before ? Being able to repeat results are what the racers are looking for...consistency is the key.


What does this mean for me and you:

It means if your a backyard basher who wants a great clutch with very easy adjustments then a Buku is perfect. But if your a racer or like to do in depth performance comparisons like me then maybe a more traditional clutch is what your looking for.


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update:

Be careful what you "upgrade"

As you can see above I am using the traxxas pinion on my buku clutch. I have never had a problem with the traxxas pinions and they are cheap and plentiful. If you upgrade to the Robinson Racing "super slipper" metal spur this is what you get:


I'm sure now that this is why they recommend you only use their own hardened pinions. The Robinson Racing slipper is also VERY heavy. The traxxas setup has never given me a single problem as of yet so I'm going back to stock traxxas. I guess those stock plastic gears are much more gentle on pinions and offer a certain amount of vibration resistance that the steel gears do not.

xanaphyst

My Feedback: (17)

Anyone running the Picco 21 besides me? I'm curious to hear what ya'll think of the engine. Mine is all wore out by now. I'd like to rebuild the Picco but have a new TRX 3.3 and Losi 3.4 to wear out first.

Tikiman1

I just installed the turbo plug version in my sons T-Maxx. I'll tell ya right away, the easy start couldn't budge this thing. Had to go pick up a pull start. Engine fired right up though. Broke it in with the heat cycle method. Haven't begun to start tuning it yet. The easy start might work now that it's broken in. I figured that I'd let the kid learn about starting them with a pull start for a while. Other new parts came in so tore it down to install them. New 3 shoe clutch, fuel lines, air filters, metal drive shaft for the rear (stock shaft was ready to snap from the stock 3.3 engine).

Shadowrevo

How many gallons did you get out of your picco p-maxx?
And did you run into any major problems with the motor dearing this time?

Tikiman1

I broke it in with a gallon of Byrons Gen 2. Had to pick up O'Donnels fuel. Only about 1/2 gallon of the O'Donnels through it right now. It was what the LHS had. It ran really hot & crappy on the O'Donnels. Too much oil in it. Very temperamental & hard to tune. I burned up the rest of the O'Donnels in my big-block T-maxx. It's my sons Maxx that I put the Picco in. Have to pick up some more Gen 2. It runs amazing with the Gen 2 in it. Runs 220F to 240F max. It's an amazing engine. With the O'Donnels it was running 240F to 270F.

xanaphyst

My Feedback: (17)

Tikiman1, I had problems with running hot when new as well, changing to the traxxas plug made a big difference for me. (As in the traxxas plug was much better)

Tikiman1

Mine only ran hot on O'Donnels fuel. It ran great on Byrons.