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engines
Dec 24, 2008 8:37:45 GMT -5
Post by Rocket R/C on Dec 24, 2008 8:37:45 GMT -5
Hey Scott great to see you on here! Thanks for helping Pete out there, I have very little OPS side exhaust experience, although I do switch carbs on quite a few engines for both tuneability issues, and or erratic behavior. I also usually need to put some sort of return mechanism, either a spring or elastic to help the slide return. It cant be too much spring back, or the servo won't open it fully, but just enough to help it back. I also use a servo with alot of torque, and relatively quick also, for my throttle. You can get away with a little less speed (but not alot mind you) to get torque to make up for sticky carbs, etc. Some carbs are just inherently junk, although lately I have found very few. It then becomes more about features, and I definitely like an alloy carb body, over a plastic, or composite. Just some food for thought if you are going to switch carbs there Pete.
As far as being stuck in the 70's..... I think its more a matter of what you like to drive. I personally dont like the engine brake characteristics of the OPS side exhaust, but it sure suits itself to a stock car. It makes it comfortable, and some have done very well with them, but its all what feels good. If you want to make a rear exhaust work, your chassis has to be spot on, or you need to be very good with the throttle. I find this much easier with a trigger vs a stick, but then that is preference too.
Great topics to discuss. I have sat with many a racer and discussed their love of the OPS side exhaust (especially Simon) and what it does for them. For some reason I just can't get it round in my head.... but I just might build a car with one to try it and see! I thought my car at the worlds was pretty quick for the most part, the weather is what screwed most of us in one way or another!
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engines
Dec 25, 2008 7:57:01 GMT -5
Post by grotty67 on Dec 25, 2008 7:57:01 GMT -5
Hey Pete, you hit the nail on the head there its all about what suits, but what i have found is that you need to stick with something for at least a full season to learn about how it works. as you may know i have just come back to racing after a 15 year break, when i came back i wanted to try new technology, i first started with an rb rear exhaust then sirio, go, nova rossi, ops etc , the list scares me! wow i spent some cash!, i tried differnet chassis and i think the best chassis for a rear exhaust was the maestro, i think this is because the chassis is designed around the rear exhaust, personally i loved the car in the wet but found it hard in the dry as i didnt like the engine breaking and it is a totally diferent style of driving to what i was previously used to, i then tried an ops rear exhaust and tried many different exhaust set ups, i made a small chamber type adapter which really helped with engine breaking, i put the set up in a Whitaker chassis and this started to feel pretty familiar, with help from Jody the car was working pretty well, then ops side exhausts came available again and i got myself a couple along with my new whitaker chassis and i just love the feel of the set up, again i think that this is because the chassis is designed around the engine. I think you have to have a great deal of respect for anyone that takes the time to try something new, what i do think is that the rear exhaust would work better if it was on the other side of the car? Merry Christmas to all who Oval
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engines
Dec 27, 2008 11:15:08 GMT -5
Post by Rocket R/C on Dec 27, 2008 11:15:08 GMT -5
Ya know Scotty you bring up a whole pile of topics there that I have been discussing with people for years, lets see if I can organize this correctly so it all flows together.
First off I am only in agreement of sticking with something for an entire year if its competitive, although I am for throwing the kitchen sink at it when its rubbish.... but the engine is usually not what I change, its always something chassis related. Yes I have piles of engines, cheap as chips over here, so why not right? However I have had some really cheap options surprise me, such as my combo that I showed up with this year..... very quick. I did redesign my rear exhaust, and believe I have found something worth developing more. I play alot with exhaust ideas, because I know that is the major difference between the side exhaust, and rear exhaust engines, and thus the braking feel related to back pressure. I think if you had a side exhaust engine with a manifold to a remote can 5 or 6 centimeters away, you would not have near the amount of engine braking that you do with the bolt on can you have now. That being said, is what makes the difference, and why I pursue the "perfect" exhaust for a rear exhaust engine. I think made some headway with my latest design, I will keep you posted on how it goes, but the first shot went very well in practice, and my last trip over.
Now onto chassis design.... the greatest topic we all can talk about. There are 2 important differences between a Maestro, and Whittaker that can have a major effect on handling. First is the engine plate in a Whittaker adds rigidity to the chassis, and takes any type of chassis twist and minimizes it. The Maestro uses the style of engine mount (unless converted to the Whittaker plate) that I produce, a sliding one piece type mount, with only a piece of 1/2 angle stock sticking out to support the rear of the mount. Much more able to twist, but overall this is the more minor of the two differences. The second difference, and the more major of the 2 is the placement of the rear axle/front steering in proportion to the bumpers. If you put the 2 cars side by side, and line up the bumpers, you will notice quite a bit of difference in the wheel placement in proportion to each other. The Whittaker has the rear axle a bit more forward than the Maestro, which Trev designed like that for a reason, thinking that a rear hit would send you more forward, rather than spin you out, which has worked well for those that drive them. Now on the front side, the Whittaker has the front wheels/beam assembly as close to the front bumper as possible, which makes steering more responsive, and puts more of the weight on the wheels where it should be, vs on the Maestro the bumper is quite a bit out in front. Trev will argue that it works well, and he has had success with it, but I feel in this regard the Whittaker has an advantage.
So what did I do??? I built the best of both worlds, and used the Maestro rear end design, wider and shorter, and the Whittaker front end design with a beam and tucked very close to the front bumper.... and ended up with a shorter car.... which I knew I would considering what I did, but it handled very well. That chassis is now retired to a show car, and I am building a new car for 09 that has alot of the same characteristics, but is a bit stiffer. I am looking for as little chassis flex as I can get, but working off the principals I just talked about with having bumpers closer, and the weight distributed correctly, I think I am on to something..... at least for my driving style!
As far as a rear exhaust engine working better on the other side of the car..... Im not sold on that yet.... maybe further forward with longer arms and a longer belt to help the car turn in.... but rules are rules, and that one you cant get away from..... engine on the right..... I think any oval car would benefit quite a bit from more left side weight, but I dont think moving it over would change it a whole lot if the exhaust and chassis were the same.... and only the engine was able to be moved.... hypothetically of course.... with a engine that ran backwards!
Just some food for thought.
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engines
Jan 2, 2009 17:08:20 GMT -5
Post by jody391 on Jan 2, 2009 17:08:20 GMT -5
I think you need to stick with the same car and change 1 thing at a time. For years ive seen people change their chassis at the end of the season time and time again.. stick with something and refine it tweak it to suit you.
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engines
Jan 7, 2009 13:43:17 GMT -5
Post by Rocket R/C on Jan 7, 2009 13:43:17 GMT -5
One change at a time I agree with completely, but I also like to make changes to the chassis in the same way.... or build a chassis from all I have learned from the previous one's.... and then go back to one change at a time.
I don't think changing the chassis is the problem with most people, it is the knowledge of how the chassis works, and their ability to set up a car. If they couldn't set up last years chassis, who's to think that they will be any better off with a new one with the same knowledge? I will agree that if you are working on the same chassis all the time, that you will get to know it very well, how it reacts to changes, what it does in certain situations, weather conditions, etc. After years of running the same thing you would think it would just be easy.... but changing the chassis can do two things, first give you a new straight car to work with... I might agree with never changing it if you never hit anything.... but this is a full contact sport, and the chassis bends, tweaks, and if that happens, it is like starting with a new chassis anyway because your corner weights are all different now, no matter how small, and how you try to straighten it. Second thing it does is give you a renewed sense that you can do well. Some people get so discouraged with racing, and doing poorly, that they just quit and do something else. I would much rather see someone get a new chassis, and be excited about racing, then keep the old one, and hardly race, or not race at all because every time they look at it on the shelf they say "that things a pile of crap, and I can't make it go.... so I will sit and watch the tele instead."
So it all depends how you look at it. We need as many racers as we can get, and the ones who are racing to want to come back.... so I say go ahead and buy a new chassis... as long as it keeps you coming back to the track. Then it becomes our job as racers (which most guys in this sport are great at) to help those that struggle with figuring it out.
Honestly we all have 4 tires touching the ground (most of the time) with 4 contact patches that are all the same size, and no matter what chassis you have, they are all within a few millimeters of being the same as far as the tarmac is concerned.... how much weight is on each contact patch, and how you deal with and change that weight is what will make you go.... back again to one change at a time!
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