More pwr fr stock hpi s25

[Magonsterz]

How to: Power Porting
HPI Nitro Star S-25

has anyone else tried the mods listed in an article from radio controlled hobbies? here is the link http://www.rccaraction.com/articles/htpporting_1.asp. i totally followed the steps and my s25 i royally spanking a wasp 26 and a mach 28. it is easy to start, does not die and runs cool. tons of torqe and gobs of mid range with clean top end. if you have any good dremel skilz you have got to try it. i am running 19 cb and 47 spur and not only flys but has xlnt midrange. i did have a 15cb and 49 spur but i could not keep the front tires down. it was a full on wheelie king on demand. if i could manage to get off the line without flipping over it would float the front end until it hit mid second gear....toatal monster no joke. i will have video soon of the drag between the mach 28......the owner of the wasp 26 does not want to play anymore. also heads up with an unmodified s25 just for comparoson.

[savagekicknmaxx]

Yea I ported just my sleeve on mine and run a 30% mix and use a cold plug, and oh yea mine will flat out scream. Its even way cooler haveing the 3 speed in it, it really really hauls now.

[hockeyizlife94]

i really want to do it to mine but i dont know anyone experienced enough to do it, and im not risking messing it up...

[guest]

same here. to chicken to try it...

[Chunky Monkey]

I'd give it a whck...can anyone copy and paste the How-To or type it in here? I'll make it a sticky for the Engine/Mods section.

[nccarpenter]

It really is easier than it looks. I tried it and had a blast. The only thing I had a problem with was finding the carbide cutter for my DREMEL.
Porting an engine is the last frontier! And the s-25 is the perfect engine to start on!

[Xjeepguy]

I have done it several times on several different engines, and it is awesome! You will have tremendous results, and the engine actually runs cooler.

[machinest 40]

i've done all of my engines from the .12 to the .30:eek: had good results with all of them.just map everything out and take your time its easy.:D

[garagedoorguy]

I'm going to try it. I thought I had th 4.6, But all my literature says it is in fact the 4.1, and I can always use more power. What duration do you guys recommend?

[garagedoorguy]

Do you just make the one groove to the intake port like shown in the istructions, or both sides. How deep of a groove is ok.

[garagedoorguy]

Well aside from the questions I had that nobody answered, I figured it out after all, and I am very pleased. Thank you Magonsterz for posting that website. Very impressive power increase. Boy those little carbide bits sure are pricey.

[hockeyizlife94]

was that the first thing youve ever ported???? and how experienced do you consider yourself with a dremel?

[savagekicknmaxx]

I was nervous about porting mine, but just took a deep breathe and just didn't think about and jumped right in. My hpi25 was my first and it came out fine. I found my dremel bits at walmart, lowes, and homedepot. I know one very important tip is take your time and take off little at a time and then pull back and inspect take a little more pull back and inspect untill you get the desired angle and material removed. All and all my p&p took about hour or so and I was pleased with it, I know if I get another motor I am pulling it apart and looking and if it will take a p&p I will do it again.

[garagedoorguy]

Yes Hockey, this the first one I have ever ported and polished. I do consider myself very experienced with a dremel, but I know you can do it. It's not that hard. I know you know where the instructions are, and it really gets you in tune with how the motor really operates. Once you figure that out it helps . If you are porting a motor that has run for a little while or more, the stains help you understand where the fuel is rushin up to the cyl., even more,because exept for the crankshaft, the hardest part, is mapping out the intake port grooves. Just keep in mind how the air or fuel is moving in or out of the cylindar. It you have a Hpi 25 just follow the instructions to a t . If you have any Questions just ask, I just did it and it is fresh in my head, and it has brought out the beast in my savage.

[garagedoorguy]

Yeah savage kicknmaxx, I was nervous, Especially since they say that if you cant afford to trash your motor, don't try it. I still did, and it worked. Thank god. It was alot of pulling back and inspecting, and being super anal. Somehow my printer cables got lost in the move, and I had to run back and forth from the garage to the house to compare parts to the website. That is why it probably took me two evenings to do. I find myself now parking my truck close to my bashing place, so I can stand on the tailgate so I don't crash into my ankle again now.

[garagedoorguy]

I could not be anymore pleased with the port and polish. I urge anyone to try it who has ever used a dremel. The only downfall that I can see, is it cuts your runtimes down a little.

[jrstorm]

garagedoorguy, what did the port and polish do? i need to go and re read the article. was it just matchiing the sleve to the ports in the block or was it changing the shape and timing of the ports?do you think using that article for a guide on a 4.6 would work or was it really instructions on your specific engine?

[garagedoorguy]

I can't say if it will work or not. The .28 is not a big difference though, and it can be done to alot of different motors. From what I understand, It gets more use out of the stroke. You make the intake in the crank larger so it stays open longer. You carve little grooves leading up to the intake of the sleeve to help rush fuel to the cyl. You grind the edges off of the bottom of the boost ports, and intake ports to smoothe the air flow, and cut out the piston skirt, because at the very bottom of the stroke the skirt blocks fuel and air would go to the boost port. I am sure I just summed up the instructions, but I've heard it done on alot of motors, and I went the low side of all the measurments. From what I see, you are just matching the sleeve to the block. Maybe a little research might be at hand, and I am curios myself so I will keep my eyes open. As what it does to the power, It's very impressive, and very noticable. I have to learn how to drive this thing again. It spent more time on its top today than ever. It was alot of fun though. I got 3 full tanks today with no problems what so ever. Well I broke the body from flipping over backwards too many times. It's unreal, and all I have done is the 3 speed and the port and polish for power. Can't wait until I get the pipe.

[garagedoorguy]

When you get the parts in your hand and read the instructions, it helps alot, especially with your engine experience. If you don't know the flow of the motor, trust me it doesn't take long to figure it out, and is like no other 2 stroke I have ever worked with.

[jrstorm]

yep from what i remember it looked like it was just making the ports match the block and then moding the crank a little.what i might do is get a second cyl and piston and break it in an then take it an port it . when i had my 4.6 appart i saw where there was some room to open the ports some and smooth the edges.but for a stock engine the ports looked pretty good. i have a wasp/diablo .28 engine and that thing is a pos. i dont see how it runs. the ports look like they used a sawzall to cut the ports. everything was rough and didnt look very good.but thats all i need to get into is starting to port and polish these engines. my buddy says ill be doing that soon. he always brings his cars and trucks for me to tune for him he says they go a lot faster after i tune them, and run better too.i dont know if i really want to start moding my engines yet,because ill jump in with both feet and modd every engine if got once i learn how to do it.oh well.

[garagedoorguy]

I would buy a cyl and piston in case it goes wrong on you. I wish I could have done that, but my engine is not that old, and I had some confidence. The feeling I get from the instructions is they took precise measurments of their cuts. I think you can kinda ballpark some things. It does cut your runtime down so if you are happy with the power you have now you might not do it.

[savagekicknmaxx]

garagedoorguy, what did the port and polish do? i need to go and re read the article. was it just matchiing the sleve to the ports in the block or was it changing the shape and timing of the ports?do you think using that article for a guide on a 4.6 would work or was it really instructions on your specific engine?

The p&p takes and angles and smooths out the sleeve and crank, and piston for better air/fuel flow. Just think of trying to take a turn at a 90 degrees now do that same turn with more of a angle you can take it faster. WHen you port the sleeve you angle the ports so the af mix gets more and faster to the cyclinder. On two strokes the faster you move the af the better horses you are going to get. On the crank all you are doing is taking off the casting marks, those creases you see are the casting marks, getting rid of those reduces turbelence and increase flow better and smoother. I don't member if that article says anything about it, on the old site we had a sticky thread on p&p work that explain it but thats simply putting it. I could research it more and go into big depth but its simply makeing less angles take out rough edges and reduceing turbelence and increaseing flow, and when you increase the af mix you also increase oil and cooling affects as well. Hope this explains it.

[garagedoorguy]

You summed it better than I could, I just don't know about taking just the casting marks off though. I probably got carried away with the polishing but I took off alot more than just the casting marks. Especially off of the crank. I have noticed that richening the mixture does have a substantial effect on temperature, but not performance. If Jrstorm comes back with good news on the nova cooling head. I think I will do that first off and I can really lean this baby and get some serios hp's.

[trashard]

hey garagedoorguy,these carbide cutters can also be coated.

[Wannus]

Help...I want to port and polish mine .25 too, but i can't get the piston sleeve out of my block..I can lift it up for abbout 3 milimeters, thats it...
Do i need extra tools or is this normal ?

[savagekicknmaxx]

Yes its normal fo rthe sleeves to be hard to get out sometimes, if you can get it up far enough past that lip you get a screwdriver under it and pry it the rest of the way out, or use a plastic rod and push up from the crank side.

[Wannus]

Thanx, i gonne try again after the weekeind, its now assambled again so i can drive this weekeind..I let you know..

[JuanPablo_Q.S.]

i can't take the piston sleeve out, please help me

[savagekicknmaxx]

Its tough but it will come out, use something gentle like a plastic rod and push up from the bottom, or use something like a zip tie and stick it into the exhaust port and get it to raise up enough to reach under the lip of the sleeve and pry or grab it to pull it out, just take your time and watch what your doing you cna chip the chome plating off the inside of the sleeve or scratchit if your not careful.

[konasavage]

do you have to upgrade all the running gear dogbones etc

[Wannus]

Can enyone help me ?
I still have the problem to get the piston sleeve out of the block.
I can't get to raise the piston sleeve up enough to reach under the lip of the sleeve.(i can lift it for 2-3 milimeters)
I tried it several times but with no result.
Is it fasten with a nut or something, i looks like it is blocked, but where ??

[Doesgo]

No, it's just a snug fit with the block. Are you trying the zip-tie trick? If so, the zip-tie can only stick through the exhaust port (from the inside) far enough to end flush with the outside edge of the sleeve. Any farther and it'll catch on the block and prevent you from lifting the sleeve more than a couple millimeters. Again, the zip-tie can only catch the sleeve, not the block!

[Wannus]

I finally got it out. The piston sleeve was blue at the outside, it has run too lean and too hot (i always want the best power when i run).
Finaly i tuned it and i did modif it all..
The result is fabules. What a throttle response !!!

[Doesgo]

Congratulations, that's awesome!

[Mondragon]

I also have done the full mod to this motor, runs great,easy tune and very usable rpms from low to high. very fast. I did the highst mod, have pics 2...

[sledman1234]

hey there name is franko check out my savy my air filter is the same setup as kn filter your local canadian tire your truck will hall *** once u get it truly tuned i found it little harder to tune but rocks my buddy got straight stock savy i run circles round him plus i got truk zilla polished tuned pipe hope this helps plus filter will only run u 16.00 $

[Cobra]

How about taking the easy way out. Does anyone sell the sleeves already ported?

[Jeremy]

I would think your better off buying a engine allready modded IMO!!!

[k0m0d067]

How about taking the easy way out. Does anyone sell the sleeves already ported?

there's a guy that offers the services done to your motor...

here's a list of his auctions, which include his modding services...very reasonable...

http://search.ebay.com/_W0QQsassZjuiskircQQhtZ-1

[SantaClaw]

I went the whole nine yards with my Nitrostar-25 Used a dremel with grinding bits on... 3 shoe alu cluch with stiffer springs.

The engine's response & low down grunt increased ALOT...

It's not THAT difficult, just take your time measuring & marking the piston sleeve correctly.

The guy I sold that engine to, asked me what the ¤"#¤ did I do to it, as it outperformed his friends 4.6 ss by a long shot... It's still running this day, after a year in a basher car, it lasted longer then the engine that came with his car... :P

He doesn't care about anything, he's all full throttle, don't change or fix anything until it falls of...

Tuning ? Thats the only thing he does well :P

[k0m0d067]

I went the whole nine yards with my Nitrostar-25 Used a dremel with grinding bits on... 3 shoe alu cluch with stiffer springs.

The engine's response & low down grunt increased ALOT...

It's not THAT difficult, just take your time measuring & marking the piston sleeve correctly.

The guy I sold that engine to, asked me what the ¤"#¤ did I do to it, as it outperformed his friends 4.6 ss by a long shot... It's still running this day, after a year in a basher car, it lasted longer then the engine that came with his car... :P

He doesn't care about anything, he's all full throttle, don't change or fix anything until it falls of...

Tuning ? Thats the only thing he does well :P

sounds like my buddy...except the tuning part...I haven't noticed his tuning yet, but he drives WOT and if something gets in his way, he drives thru it, or over it...LOL

[killermiller]

That link is broken... I looked around the site and found a link with no pictures (http://www.rccaraction.com/ME2/dirmod.asp?sid=8375E1E1A7444F68BDD181959263DB0F&nm=The+Magazine&type=PubPagi&mod=Publications%3A%3AArticle+Title&mid=13B2F0D0AFA04476A2ACC02ED28A405F&tier=4&id=8F70346FB9D94F1D96674F0B8E550C2D)

[k0m0d067]

That link is broken... I looked around the site and found a link with no pictures (http://www.rccaraction.com/ME2/dirmod.asp?sid=8375E1E1A7444F68BDD181959263DB0F&nm=The+Magazine&type=PubPagi&mod=Publications%3A%3AArticle+Title&mid=13B2F0D0AFA04476A2ACC02ED28A405F&tier=4&id=8F70346FB9D94F1D96674F0B8E550C2D)

that's the exact article that was originally linked at the beginning of this thread...I believe they moved it to their archives, and the pictures were probably removed to save space...

nice find...too bad about the pics though...

[killermiller]

I wish there were pics so I could see what and where to cut. Anybody have a journal or log of their work?

[MTBikerTim]

It definately sucks the pictures are gone. My S-25 is a POS performance wise. It has never run well and that is getting guys who not what they are doing to try to fix it. It would be fun to try and port my s25 as I don't care if i stuff it.

[DOOBEEWHA]

I'd give it a whck...can anyone copy and paste the How-To or type it in here? I'll make it a sticky for the Engine/Mods section.
Hey Chunky, I know this is an old post, but if your still looking for the artical, you might find that savagecre has a copie of it.

PM him about it and maybe he can fax or e-mail it to you. just thought you might want to know. good luck

[MTBikerTim]

Thanks doobeewha. Chunky might not want it but i know i do. Thanks. I might pm him.

[DOOBEEWHA]

Thats cool, MTBiker,
Savagecre is pretty cool dude and would do what he could to help anyone. I will have to warn you though, IF HE still has the artical at his fingertips, it may be black and white.

I was thinking (imagine that...lol) that one of us could get a hold of the magazine that printed it....
They might be cool enough to look into their achives and find the missing links we need and possibly give us the the whole artical intact with the original color pics.

Then we could lock it in our own archive database, for safe keeping. Sound like a plan, anyone?....
Just a thought..

What's really great about this purticular artical is that it helps break down the fear factor in doing your own P & P work.

While it still warns us to be very careful and aware of your cuts, it's in a really cool short form presentation, and gets you rolling in the project without alot of techical
dogma that discourages the average newbie from even trying.

It's worth it to this forum to have it in it's archives, without question.

In fact, I was really tempted to go and get a HPI 25 mill and proform this procedure, just to see the difference.

I hope one of us has the drive to get this artical restored to it's original state.
Who ever does this will have a feather in their hat, as far as I'm conserned.
The name of the Magizine has been stated in this thread.
All we really need is the photographer's insight.
He may be the person that has a personal record of his pics history.

Infact, he might be able to get us a much better resolution of these pics, compared to the reduced sizes that Mags do to their pics.

Heck, We could probably buy the back issue from the Mag itself and scan in the pics with a snanner, if there was no other option...


Who ever pulls this off should start a thread devoted to this artical.

======================Good luck to those who attempt this research.==========================

[MTBikerTim]

I have actually been tempted to send them an e-mail to see if they could fix it. but I couldn't find an e-mail address.

edit: don't mind me i found the e-mail address and e-mailed them.

[DOOBEEWHA]

Well don't give up there, bro.... Improvise.

[Wannus]

I have found a copy of the HTML files of port tuning the NitroStar .25 engine. Give me a PM with your e-mail adres and i will e-mail them to you..

[DOOBEEWHA]

Hey wannus. I just want to tell you that I PM'd you while you were on the site. Any reason why I havent't heard from you?

[Wannus]

Sorry, just been away for a couple of hours.
I have e-mailed you..

[DOOBEEWHA]

Ok my friend. I'll resond to your e-mail

[Bergowitz]

Has anyone got the whole article incl. pictures ? Because I just bought a STS D30M and I thought that I would try this on my "old" S25 then. Just to see how much more power I could get out of it.

[Wannus]

Bergowitz..
Check this out.
http://www.hpisavageforum.com/forums/showthread.php?t=2650&page=3
There are some PDF files you can open in Acrobat reader with the P&P work in it..
Have fun..

[Bergowitz]

Thank you Wannus
I think I will give it at shot.

[NitroNation]

i tried to mod my axial 28 and i screwed it up bigtime........the engine was making all of these weird noises......the engine also was revving way too high for too long......didnt calm down after the truck slowed down and eventually stopped......overall it messed up the engine bigtime....

[NitroNation]

i do not recommend modding an engine unless you have 100% steady hands and you know what you are doing because it will most likely not work and screw up the engine......... JUST SO EVERY1 who didnt do it yet knows....

[BIGDAN89]

i got ny star 25 modded by a great guy from s&w mods wich he dosent do bussiness any more but it hauls he did the crank carb and everthing i run 30 ace by trinty and i get 20 mins of runtime on wot whole time

[chrisw]

I am going to try to mod mine 25 when i get the lrp

[Chris]

Maybe a little late, but I just joined this board so forgive me. hehe

I wrote up my own article based off of that S-25 porting guide...pictures included. Here it is guys. PM me if you want the Word doc.

Here we go with the specs...

The sleeve first:

Brass coated with chrome...easy to grind.

For 160-degree duration raise the top of the exhaust port .012". The top of the port will be ~.530" from the top edge of the sleeve.

For 165-degree duration raise the top of the exhaust port .025". The top of the port will be ~.517" from the top edge of the sleeve.

For 170-degree duration raise the top of the exhaust port .035". The top of the port will be ~.507" from the top edge of the sleeve.

It should be noted that if you go for 170 degrees, then grinding will need to happen on the roof of the exhaust port of the block/case. At this point the port is larger than the opening in the block.

Flow grooves on the transfer ports:

Each transfer port will receive a groove running from the *inner* corner of the transfer port to the bottom of the sleeve angled towards the exhaust port (check the picture)...this is viewed with the exhaust port facing you. It's important to match the blocks' internal angles so this is how to do it. Mark a line on the inner side of each port (nearest the exhaust port) straight down to the bottom of the sleeve. From that line, mark another .220" inward again towards the exhaust port. From this inner line to the inner edge of the transfer port will give you your proper angle. Sounds hard, but is really quite easy. Again reference the pictures.

http://i4.photobucket.com/albums/y121/go-to73/Misc/63685a00.jpg

http://i4.photobucket.com/albums/y121/go-to73/Misc/7e04ed21.jpg

Bevel on bottoms of boost ports:

Can't put this into words really...check the picture.

http://i4.photobucket.com/albums/y121/go-to73/Misc/24e9615b.jpg

Piston skirt notch:

Aluminum part and easy to grind. .540 x .375 is certainly not right...so I'm going with .540 x .175 which will suffice. This is just to clear some room for flow at BDC. Check the picture. You want to center your notch at the wrist pin. Don't get it skewed to one side or the other.

http://i4.photobucket.com/albums/y121/go-to73/Misc/15dc90dc.jpg

http://i4.photobucket.com/albums/y121/go-to73/Misc/5894fb24.jpg

http://i4.photobucket.com/albums/y121/go-to73/Misc/e17b307c.jpg

Con-rod knife edging

Aluminum part and easy to grind. Simply put...grind a sharp edge on the connecting rod. Most of the work is already done, so why not finish the job?! Follow the angle already cut into the rod.

http://i4.photobucket.com/albums/y121/go-to73/Misc/4e8bdc2e.jpg

Crank timing

This was the hardest for me because there's no good picture to show exactly what to cut! So I just stuck the crank back into the motor housing and rotated the crank to see what was going on. Easy enough, but unlike the other pieces the crank is made of steel and is much harder to grind. You'll need a sharp bit for this part. Again the picture is worth 1000 words.

Remove .098" from the leading edge of the port to increase timing to 210 degrees. Also, smooth out any rough edges you may find inside the port. A mirror finish is *not* needed, but certainly helpful if you wish to spend the extra time. These pictures are un-finished and not polished yet.

http://i4.photobucket.com/albums/y121/go-to73/Misc/8b235b80.jpg

http://i4.photobucket.com/albums/y121/go-to73/Misc/4e92c9f4.jpg

http://i4.photobucket.com/albums/y121/go-to73/Misc/ee9b608a.jpg

Lastly:

Head shims. The (3) shims create excessive clearance. Removing 1 or 2 shims (make sure and check this), will increase compression. If you burn up glow plugs quickly, then replace 1 shim at a time.

[Jeremy]

WOW dude you milled that mill .. How did it run for ya

Thanks man

[k0m0d067]

+Rep to the new guy for an AWESOME right-up...very well done, and I have to agree...pictures ARE worth a thousand words!!

[Chris]

WOW dude you milled that mill .. How did it run for ya

Thanks man

The thing screamed on top-end. I grew up under a rail with a SBC so I just *loved* the sound of that thing making such RPM's. It really did roll man!

I never got to try it with an 086 or similar pipe so it had more I know it...

[Chris]

+Rep to the new guy for an AWESOME right-up...very well done, and I have to agree...pictures ARE worth a thousand words!!

Thanks man!

I should note this was my mock-up job...these were the piston/sleeve I had to damage to remove.

The crank was also unfinished at this point, and for some reason never took pics of the new finished pieces. :duh:

Thanks again!

[SunkenMetal]

Nice Right up Go-To, so yeah i dont think anyone is thinking new guy status.....+Rep

[Chris]

Nice Right up Go-To, so yeah i dont think anyone is thinking new guy status.....+Rep

How's that rep points stuff work?

I don't mind taking my licks to get to where I need to be...I *am* the new guy here basically. dance kitty

[Shaun]

great post!! porting seems to be really catching on!!

[SunkenMetal]

How's that rep points stuff work?

I don't mind taking my licks to get to where I need to be...I *am* the new guy here basically. dance kitty


Here is a link to the explination....http://www.hpisavageforum.com/forums/showthread.php?t=5361

basically we give eachother rep points the little green bar, and use the points to buy gifts for people....

[Chris]

great post!! porting seems to be really catching on!!

Thanks!

Yes, I should've warned people that you can pooch your motor in a hurry if you don't know what you are doing.

These specs are for an S-25 *only* BTW.

[Chris]

Here is a link to the explination....http://www.hpisavageforum.com/forums/showthread.php?t=5361

basically we give eachother rep points the little green bar, and use the points to buy gifts for people....

Thanks. VERY cool!

[SunkenMetal]

Thanks. VERY cool!

No Problem, thats what here to do, help eachother out....