Anyone Do Their Own Porting?

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If we started with a 27cc and ended at 34cc sure.Big bore to me is swapping for a larger piston. Strokers(large engines) can lead to big blocks but their blocks and cranks allow larger machining...id say we are really limited here and thats why alot of people jump to rc max and alx because these engines are maxed out on potential. Honestly I like right where there at with power for what I do. And the price is right I couldn't afford to blow up an alx or rc max engine.
 
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MonsterAir said:
I was just watching that vid!.... Well isn't a +2mm stroker with machined head considered a big bore?.... I was thinking the same about have a local machine shop do a few for me but now that I'm learning these cases need more room to accommodate the stroker cranks this whole endeavor seems kind of useless. If all the major performance mods need to be done with heavy machinery then I guess I'll be stuck buying OBR or ESP gear.



For some reason I feel like this isn't the proper way. lol


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don’t grind the crankshaft lol. Just the case.
 
Yeah guys doing case work and port work isnt hard, the video of Scott doing the squish band is what I was talking about, his method is rather un scientific but it works non the less. And big bore kits don't necessarily mean more power, what you see in the saw realm really depends in port numbers, and cylinder quality typically they take a lot of work to get to factory top end power, if it ever can. Our stroker kits re use the factory top end, so really it's not a big bore kit and the bore is the same size, yes displacement is increased, but it's not like taking a 94 cc engine and blowing it out to 101cc.
Porting in the other hand isnt really rocket science once you figure it out. I can guarantee you'll mess a few up before you figure it out, try it on a junk cylinder to get the feel of how the metal cuts and go from there.
 
hi gents. i am also new to gas cars and like to do my own port work. i am racing gas boats and modify my own motors. this is new ball game for me and i really look forward to mod my first baja motor. i read many guys like to used thinner gaskets or want to stroke motors, but by doing that you change the timings on the motor. funny that timing nrs are not mentioned anywhere, why? top secret detail? by swoping cranks and gaskets intake and exchaust timing change, and this is only the start by mod motors. thanks for a brilliant forum. i still have much to learn.
 
None of the "ported" stuff available I've seen has done much actual port work, I haven't seen the inside of an obr or bart engine, and for what we mostly use alx and rc max don't matter much. The thinners gaskets to make up for squish doesn't seem to affect how they run much, typically raising the port roof would be advantageous, but I like the lower exhaust roof to begin with, and theres not a lot of meat to play with the intake port to raise it. I also haven't found a good reason (performance wise) to raise the transfers either, making the intake side transfer a bit wider seems to help a good bit, as well as squaring off the port roofs. Not a lot of real estate to work with on these things, which I'm sure you know from your boat work. On my g320 I raised the intake roof 2* but couldnt tell you weather it helped a lot or not, just after i was finished with all the port work I was able to go up 2 teeth on my spur gear, and not loose much in the bottom end. When your dealing with stroker kits, you machine your squish band to get the height and set squish at the same time, so really the numbers change quite a bit, but again it doesn't seem to matter to the production guys. I have both a red arrow and esp stroker top ends and neither have done much port work. Transfers on both were done up a bit, but little and no intake or exhaust work done. The esp did polish the ports, but (imo) that doesn't do a lot on an already nicely cast surface. On my own port jobs, I found widening the exhaust port helped far more then raising it, and tbh theres no point to lower it, the piston is the limiting factor for that. I would like to relief cut a piston and see how it acts, but I really don't want to sacrifice torque for a few more r up top.
 
john addinall said:
hi gents. i am also new to gas cars and like to do my own port work. i am racing gas boats and modify my own motors. this is new ball game for me and i really look forward to mod my first baja motor. i read many guys like to used thinner gaskets or want to stroke motors, but by doing that you change the timings on the motor. funny that timing nrs are not mentioned anywhere, why? top secret detail? by swoping cranks and gaskets intake and exchaust timing change, and this is only the start by mod motors. thanks for a brilliant forum. i still have much to learn.
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Are you 100% sure the timing needs to be changed when adding a stroker? I'm not sure it is as I've seen a few kits that use just gaskets to get clearence for the stroke..... One thing I'm stuck on is having to make clearance for the stroker crank. If this is needed to be done then why don't these kits like on DDM say so? I was under the impression the +2mm were drop in options that didn't need modification to fit.


https://www.davesmotors.com/30-5cc-big-bore-combo-kit-3-75-hp



Very true Sean. I don't think they do much on the porting side of things (these big names). ESP charges like an extra $50-$75 for that polish too! Though it seems OBR is using a CNC for their work so maybe they are able to take it a little further than we can by hand as well as keep things consistant.
 
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MonsterAir said:
Do you guys believe the OBR HP numbers? They seem a little made up to me.
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Tbh, it's all opinion. They get their numbers from their dyno, so they don't just pull en out if their ass, but it's questionable weather their dyno is correctly calibrated. I personally think they are a bit optimistic, but their motors feking rip so it doesn't really matter to me. I don't look at hp numbers when buying a motor, I just see how well they perform in the real world. Hp is just a number
 
Yea I know that every dyno is going to produce different numbers for these motors but they definitely do seem more optimistic than ESP with their ratings. I have both ESP and OBR heads. Both 27.2cc and didn't notice a difference between them. Both made my marder faster than anything else I've come across so I'm with ya on they rip balls lol. Most guys seem to run the 30.5cc and I think the 27.2 just revs higher and get's me there faster.
 
MonsterAir said:
Are you 100% sure the timing needs to be changed when adding a stroker? I'm not sure it is as I've seen a few kits that use just gaskets to get clearence for the stroke..... One thing I'm stuck on is having to make clearance for the stroker crank. If this is needed to be done then why don't these kits like on DDM say so? I was under the impression the +2mm were drop in options that didn't need modification to fit.

All my motors are ported and modded so I don't even have one to play around with and see how things fit.

https://www.davesmotors.com/30-5cc-big-bore-combo-kit-3-75-hp



Very true Sean. I don't think they do much on the porting side of things (these big names). ESP charges like an extra $50-$75 for that polish too! Though it seems OBR is using a CNC for their work so maybe they are able to take it a little further than we can by hand as well as keep things consistant.
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If you added 6" OF stroke you would have to move the ports , otherwise it just adds to the capacity of the bottom end air/fuel mixture right ? which would increase power because of a higher amount of air/fuel that can go into the top end. with a custom motor like AXL/OBR you can design all that into your castings/billet material. , if you don't move the ports your displacement would stay the same IMO , the point that the piston/ring closes the exhaust port is where your displacement/compression starts .
 
Here is my rig with a semi warn clutch and a diff that needs more locking. OBR 27.2cc top end.




@buzzkill.... I get that and understand what your saying but these motors are small and we're talking 2mm,3mm of stroke so I don't see how timing on these engines will change to the point where we won't see gains.... I am picking up what your laying down tho.
 
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MonsterAir said:
Here is my rig with a semi warn clutch and a diff that needs more locking. OBR 27.2cc top end.




@buzzkill.... I get that and understand what your saying but these motors are small and we're talking 2mm,3mm of stroke so I don't see how timing on these engines will change to the point where we won't see gains.... I am picking up what your laying down tho.
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Im just going over it in my head . making things crazy big # wise make it easier for my FEEBLE BRAIN to get a handle on it !!! LOL :eek:
Is that a RACE TRACK or what ?
 
The port numbers arw all.lowered by just taking material from the top of the cylinder. Like I've said before. Raising the exhaust will gain a few more rpm, but hurt torque. Raising the intake is hard because of lack of material thickness in the casting, meaning you would have to trim the piston skirt. As many know it doesn't seem to be a major factor in how these little engines run. Actually the timing would stay the same compared to before, just be start and stop at different times relative to the new stroke, again I don't think it's a huge deal. And finally to compare porting we all need to be talking about the same base cylinder. For sake of argument let's stick to the zen 32cc engine and it's off spring/clones
 
@buzzkill.... It's a giant parking lot that a bunch of us meet at on Sundays and run on-road. Which for me was the Marder with grp TC tires. We have cut tires we use for the turn markers and when we have big races someone brings a couple actual fire hoses for lane dividers.... One of the guys would bring a giant blower to clean the area but at that time he hadn't been coming so tons of sand which is why you hear me blipping the throttle.


 
Seandonato73 said:
The port numbers arw all.lowered by just taking material from the top of the cylinder. Like I've said before. Raising the exhaust will gain a few more rpm, but hurt torque. Raising the intake is hard because of lack of material thickness in the casting, meaning you would have to trim the piston skirt. As many know it doesn't seem to be a major factor in how these little engines run. Actually the timing would stay the same compared to before, just be start and stop at different times relative to the new stroke, again I don't think it's a huge deal. And finally to compare porting we all need to be talking about the same base cylinder. For sake of argument let's stick to the zen 32cc engine and it's off spring/clones
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so theres enough MEAT in the top end to remove 2mm of material I assume , hence the 2mm stroker crank ? , that then adds the 2mm of displacement as well , Ok I got it now lol so about a 7-8% increase in displacement as well as porting . From what I have read the 32cc motor has the highest RPM and or power / CC any idea why ? geometry ??
 
Expecting a parts delivery tomorrow for my new/used rig, so I figured I'd pull the motor tonight and clean, re-ring and replace gaskets. Well look what I found! How do ya suppose that happened lol.


No deep scoring in the cylinder so I'm lost on how something like this would happen and talk about chitty oil. The last owner did not take care of this thing well.
 

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buzzkill said:
so theres enough MEAT in the top end to remove 2mm of material I assume , hence the 2mm stroker crank ? , that then adds the 2mm of displacement as well , Ok I got it now lol so about a 7-8% increase in displacement as well as porting . From what I have read the 32cc motor has the highest RPM and or power / CC any idea why ? geometry ??
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Well that's a loaded question. Its the "biggest" of the small bores, and it's a much better cylinder design (imo) than the smaller engines. Which can hurt its top rpm range, but typically makes up for it in the torque department. But really it's all dependent in how it's set up and ported.
From what I've seen, theres more then enough meat to take out of the top for the stroker crank. don't see anyone running spacers.
 
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