The Great Engine Builder Debate in Lo206

4 Stroke Kart Engine Forum
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It’s high-risk and that drives part of the reward mechanisms in those that cheat. Part of the fun for people is seeing what they can get through scrutineering. It’s not so much about winning, it’s about the whole fact you might get caught. And int he end the worst that could happen is you get thrown out… but people that cheat don’t care that much.

I’ve always been an advocate for open formula. Reward ingenuity and intelligence rather than push it to the fringes where it often manifests in cheating. It will always happen, especially when things get competitive.

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43

Only to play Devil’s advocate here:

If I am an engine builder (I am not) and I know there is gains to be made and I stay within the specifications listed in the rules, how do I not do it? Who do I sell this engine to that I know is 0.3 hp down on power? With a straight face?

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44

I will say, I can definitely tell a difference in .4 hp on a KA, there’s definitely a difference in a 206 with .3 or .4 hp. KA’s dyno at 19 hp on our dyno at the shop, my bullet motor hits 19.5 vs. 19.1 from the practice engine. That’s a 2.1% difference in power but I can feel a difference when I’m on track. There’s also more to engines making power and being fast than just peak hp, actually I consider peak hp to be the least important part of the dyno curve.

For an engine builder (which I am not either, I just work in the shop prepping karts) the two options I see are either truly distributing engines randomly, which will end up giving bad motors to good drivers that will notice the shortcoming of that motor eventually, or pick and choose who a good engine will make a difference for.

One is arguably more “fair” but will definitely result in lost customers if the wrong driver gets a bad motor or too many bad motors in a given time. The other is probably less fair and playing favorites, but I see a case for it being better for the engine builder and possibly being inconsequential for the drivers (I’m also a big proponent of drivers not getting the best equipment until they’re ready, development wise I think there’s a benefit to having to learn to fight uphill when you’re starting out). It’s definitely a tough spot to be in for an engine builder when you know you have a weaker engine.

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45

I’ll add one more reason to have a reputable builder do your work. My buddy bought a brand new engine last season, took it to a well regarded engine builder for a simple break in and carb tune, engine builder found it had a slightly bent valve stem from Briggs, so he had to replace the valve and cut the seat in a brand new engine.

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Wow! That’s stunning. What is someone who doesn’t take it to a builder supposed to do?

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To me, this just seems like such a rare occurrence that it shouldn’t be considered a factor in deciding to use a builder or not.

If you really wanted to, you could check the straightness of the valve stems too. That isn’t anything technical or super specialized to necessitate a builder for.

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Spencer, you have to look at the average 206 racer. The average 206 racer barely knows how to change the oil. Let alone take the head off to check valve straightness.

You would think things like this are rare occurrences, but they really are not. Back when we were building engines, I would find everything from loose head bolts to jets missing from carbs to loose roacker arms to undrilled passages in carbs. Not all the time, but probably 1 in 10 engines had some major issue that I would think the “average” racer would not have caught.

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49

Close to 2 years ago we bought (3) new engines from a builder with a solid reputaion. Dyno sheets were provided, and I was shocked to see a maximum difference of darn near .8hp between the best and worst one. How do you then decide as a builder, who gets what?

Second to that, one engine was not even close to being setup correctly (valve lash was off, float levels were off, etc). Now granted I should have checked that stuff, but we were new to 206 at that time and I “assumed” everything was correct, given the info above.

Builders buy 100 engines at a time. Cherry pick the best of those 10, then go through them. Take every part you can to max legal tolerences. Dyno tune it. I’d be willing to bet you could gain 1hp pretty easy between and engine that just wasn’t the best from the factory, vs one that came out strong and has been worked over.

For reference, we are running Stewarts right now. He has treated us well and I while there are some things about his program I don’t love, I feel that the motors I get from him are good enough to put us in position to do well and not lose a race based soley on someone that had something “that” much better.

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Sounds like they came out of the box, on the dyno and straight to you with no work.

Engines typically go out in order of how the orders come in as the boxes are opened from almost every builder I personally know. None of them are keeping the good ones in-house or setting them aside for special drivers.

Not many of us have the resources to do this.

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51

There’s not an engine builder in the country buying 100 at a time. Comet at its peak wasnt even doing that. Gary will be the closest to that number and even if he did order 100, Briggs would only give him 18 at a time (ask me how i know…).

If your engine builder sent you two engines that were 0.8hp apart, he wasn’t as reputable as you think he was.

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52

If that’s the case, and they sold them “out of the box” but advertised them as “worked” engines and charged for it, then that is BS x 2. I’m not saying they did that; I’m just sharing my experience.

You must have a lot of trust with your builder. After running stock moto, I 'm reluctant. Let’s take a hypothetical situation for review quickly.

Joe Blow Engines (JBE) are very popular, you see them winning at most tracks you go to. JBE has a large customer base, many of whom purchase over 10 engines a year and have been with him for years. Let’s say one of these customers, call him customer “A”, needs a new engine. Customer A has been a loyal paying customer and is a strong competitor, winning races on a regular basis. At the same time, JBE receives a phone call from a brand-new customer, call him customer “B”. Customer B wants the best of the best and is willing to pay for it. He needs an engine as soon as JBE can supply it. JBE just happens to have 2 engines ready to go, the last 2 he finished. One has .5hp more than the other. You are telling me that JBE is going to send the better engine to customer B if he happens to be “in line” for that engine? I think that takes a very special person to adhere to something like that. It’s a difficult position for JBE or ANY builder to be in. Who’s to say who should get that engine? Should you not take care of a loyal customer? Should you do a disservice to a new customer willing to pay for the best?

And I’m not saying people buy 100 engines, but I don’t think that would be out of line for the most popular builders in the country to be ordering those types of quantities. Call it 50, call it 20. You still don’t think out of 20, there are a few that are better?

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It’s definitely safe to say they are better engines than others. Whether or not they save them for “priority customers” is a different story. If you really cared about your brand and business why not give the monster to the new guy?

I’m sure the new guy will have a great deal of confidence with his new builder to know he’s not getting shorted anything

It always blows my mind how much money people spend on 206 (myself included :smiling_face_with_tear:)

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54

Agree, based on the 1,000s (literally) of 206 dyno curves I’ve been privvy to, failing a major mechanical malady, the spread coming in was about .8 from worst to best and 0.2 going out.

One thing worth noting is that those bumps are for a broad part of the curve. That’s to say you’re looking at a steady .2 across the range.

The work basically comes down to making sure the engine gets what it needs in the fuel curve, getting the idle speed screw out of the way and checking the valve clearances.

Honestly there’s a lot of BS talked about engines and cherry picking in general. It for sure happens, but the difference it makes is not as much as we’re lead to believe. At least not with the likes of 206, KA100 etc. clone is another story altogether but it’s not intended for racing anyway.

To me, it’s mostly a psychological game…. If someone can convince you that they have the upper hand (even when they don’t)

Now some would say, that 0.2HP is a lot, which is fair.

My question is…… how much parity can we reasonably expect? I’d say that 2% is probably about the best, maybe? I’ve only ever seen 206 curves en-masse.

When it comes to KA “vs” 206, worth noting that extracting maximum performance on the day is arguably more of a challenge compared to a 206. So while you could have a strong (or not strong) engine on the dyno…. It’s a different story tuning it to the track, on the day. You can even blow one up if you tune in the wrong direction. That’s not as much of a worry with a 206.

You also have things like carb diaphragms, pop
off pressure etc to consider.

As I always say, do what’s best for you. Take in all the factors and don’t let yourself be pushed into some sort of perceived hierarchy.

Another thing I say…. You cannot stop people spending big amounts of money in Motorsport.
What you CAN do, is limit the difference is makes on track.

Thank you for coming to my Ted Talk.

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55

Do you think it really matters when the biggest difference I’ve seen is .3 best to worse on healthy prepped engines?

Once again. Give me one at the bottom of the spread and give me one the top. No difference on track with the same driver/kart.

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Great Ted Talk.
Questions to ask your engine builder after looking at the power curve data are:
1 What was the correction factor?
2 Can I see the data collected for the correction factor on the day it was on dyno

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57

Take 2 karts. Equal driving. Equal chassis performance. Everything else being equal, you feel .3 is not going to make a difference?

Sorry, I don’t buy that. Go look at sprint cars. They spend thousands of dollars in titanium hardware to take OUNCES off a 1,400lb car with 900hp. To top it off, the only reason they took those ounces off were to just relocate it in the form of ballest in another part of the car.

It all adds up. Maybe you don’t care about .3hp. I want every advantage I can get when I go to the racetrack.

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This thread is getting laughable. Go read the posts in this thread from June of 2022. There’s not a person in this forums who has lost a race because the guy in front of them had 0.3hp up on them.

I had access to 100’s of engines back when Ghost Racing was in its prime. We never once had one so good we “had to cherry pick it”. In fact, Matt won a few championships on engines that were what would be considered “mid pack”.

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59

One example of on-track results:

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P1-P5 were packed from lap 3 or so to the last couple when P3-P5 got racey.

P3 and P4 came from last row.

You can swap any of the top 5 engines with ANY semi-healthy engine in the paddock and the results and laptimes are going to be the same.

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It was a dynomite with a weather station. All of runs used the same correction method (not sure which is was).

To be honest, if you’re working with a non bullshitting dyno operator, the correction factor is a bit of a red herring.

You just need to be aware of what the method in use is and what the tolerances are for that correction method.

For example, the correction factor I use on my dyno (I can’t remember what method it is) has a max validity of +/- 7%. Ie, if the correction factor is beyond 7% the run is considered invalid. So basically if it’s too warm or too cold in the day, technically the numbers are not valid. I think the reference point is 70F

Now comparing runs between dynos and/or correction methods (as opposed to factors) is a whole other can of worms.

But the runs I reviewed (not on my dyno, but one that’s dedicated to 206 work) were valid and all on the same dyno, logged air density, humidity, temp and lambda.

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61

And most of these guys roll out their back up car when they total their main car and go just as fast without all that titanium or without their “A” motor. You cant compare money spent on a $100k sprint car to money spent on a $3k go kart.

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