my friend swears this is true but cant explain y. hes trying to say if u drive your car nice and perfect, nothing stupid and not getting on the gas(granny driveing) it makes the car slower because u are not opening her up?? is this true is it a good thing to get on the gas? like once i day open her up a couple times??? he told me a stoy about his friend when he first put his 350 in he would always romp on it then got tired of dishing out 20$ a day lol so he granny drove it alot then when he would get on it was slower

oh and one more thing does putting on 17" rims and 255/40/zr17 tires make the car slower then it would be with the stocker 15"??? stupid qiestions i know but i just wanna get this strate and know the truth but i have no clue if this these things are BS or true.

 

He's actually somewhat right, but he probably doesn't know why. When an engine spends most of it's life at idle or near it has a tendancy to carbonize, resulting in less efficient combustions resulting in more carbonization....kind of catch 22....occasionaly going through the range of rpms helps clean combustion chambers and top of the cylinders.

If the diameter of the tires are different, then the gearing changes and can possibly change the acceleration of the vehicle. Whether it will slower or faster is impossible to predict without more detailed information...

 

No, as long as you properly maintain the car the engines maximum power capabilities wont change.

Yes and no. The dia. of the wheel assembly will raise the final drive ratio if its dia is larger then that of the stocker. It may also weigh more and add rotating inertia that is additionally parasitic to engine power.

 

i think what your friend means, is that when you baby it, you can build a ridge on the cylinder wall where the piston will not travel any further.

 

Yea, you gotta wind it out once in a while to keep it in top condition, because it knocks out alot of the carbon buildup on your pistons, heads and in your exhaust system.

As for the wheels... one thing I haven't heard yet mentioned, is that a 17" wheel is probably heavier than a 15" wheel made of the same material. A heavier wheel will slow it down a bit, but probably not much of anything at all.

 

What?


The piston will only travel as far as the crank and rods will let it no matter what. THe ridge is caused by cylinder wear not by anything else.

 

What CAN happen to an engine that is constantly operated in the lower load and RPM ranges is that fuel deposits can develop and build up on the top sides of the intake valves. This will reduce the maximum available flow, so that when you finally DO "get on it", the flow (and resultant power output) will be more restricted.

However, that CAN also happen to an engine that is driven hard, so it isn't a rigid rule.

Another thing that can happen to lower RPM engines is that the cooling system flows are never at peak, so deposits can build up in remote pockets of the castings. The same thing can happen to the lubrication system, since overall oil flow and splash lube are reduced, and the resultant washdown of the interior is not as effective. As mentioned, correct maintenance can eliminate those effects.

Tires and wheels can affect performance, and can affect apparent performance if you don't correct the speedometer for a different tire/wheel installation. The mass of the tires/wheels will affect acceleration, but once moving, it won't affect top speed in any measurable amount - not one bit in a practical world. Momental, inertial, and delta forces all apply.

 

That's not quite true. A rod will stretch just a wee bit when the piston stops at the top of the exhaust stroke. It may not be much, but there's no such thing as a perfectly stiff metal - even a beefy connecting rod.

When an engine is operated at a higher RPM, the rod has to "pull" harder on the piston to stop it on that exhaust stroke. So, the rod will stretch just a little bit more at high RPMs than it will at low. The ridge formed at low RPM operation only will therefore be lower in the bore than the ridge formed by higher RPM operation.

That's no excuse to go "blow the cobwebs out" every once in awhile, though.