Maybe you guys can answer a question I have. When ever I go on forums or talk to people they always say that wow you should not put those gears into your car or they tell other people on forum not to do that. They say that you will be driving while your engine is in high RPMS. Why does high RPMs matter? Well I have a th350 and 4.10 gears with a 402 big block in my 86 EL Camino. Now people tell me your be driving in the high RPMs and you should either get smaller gears or get an overdrive transmission. I do not understand what people are telling me. Can someone explain this to me.
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The high RPM's translates into wear and tear on the engine and lower fuel economy.
Lots of high performance motors don't really like to spin at 3000-4000 RPM's for extended periods of time like they would see on a longer freeway trip.
But it really all boils down to a matter of personal preference.
If you don't mind it, then leave it alone!
Lots of high performance motors don't really like to spin at 3000-4000 RPM's for extended periods of time like they would see on a longer freeway trip.
But it really all boils down to a matter of personal preference.
If you don't mind it, then leave it alone!
The problem with the engine running at high RPM just for your regular freeway cruising speeds is you are putting more stress on the engine and using more fuel. If you can cruise at a lower RPM range you won't have as much wear on the engine and your fuel economy goes up. The gear ratio will also effect the top end speed, higher gear ratio you will have generally have a faster top end speed but slower acceleration. The goal is to find a gear ratio that will compliment your engine power giving you a balance of both your acceleration and top end speed. However you have to take into consideration your transmission gearing, rear gear ratio and tire size on the rear.
The reason people are telling you to get an overdrive transmission is because theres more gears to go through to get up to speed, which will keep your rps lower and also increase acceleration, and give you more top speed. Picture yourself riding a 10 speed bike, the more gears you have to go through, the easier it is to pedal and the quicker you will get up to speed, as opossed to starting on one of the bigger sprockets ( sorry i cant provide a better explanation than that, i suck at explaining things) If you have 4.10's with a th350 im sure your really screaming on the highway, but like blake said, if it doesnt bother you and you dont mind that it wears your engine out quicker, dont mess with it.
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I run a TH350 with 3.73 gears on a sbc 350. IT SUCKS! Going down the highway for an extended period of time, exhaust noise making it sound like your doing circle track and only going 70mph. I would be going down the highway doing 70mph at 4000rpm. It's a little easier, IMO, with a small block than it is a big block cause a lot of big block motors just don't like driving at high rpms, as mentioned.
So now, after snapping my driveshaft, I bought a 700r4 from a buddy of mine, along with a driveshaft and 4 speed megashifter, and am in the process of getting that 4th gear so I can cruise on the highway happily, get better gas mileage, and have a higher top speed.
So now, after snapping my driveshaft, I bought a 700r4 from a buddy of mine, along with a driveshaft and 4 speed megashifter, and am in the process of getting that 4th gear so I can cruise on the highway happily, get better gas mileage, and have a higher top speed.
Well I do not really drive on the highway at all with my El Camino. I drive it less then 2000 miles a year. Also the only trip I take on the highway is to Carlisle PA witch is about 2:35 hrs. So would it matter much?
On a trip that long I would take it easy. I have 4.11's in my cutlass, I drive mine a bunch more than 2000 a year. My rear end gets pretty hot after a bunch of driving around at 60 mph and then in town driving.
Take that 10 speed bicycle put it in 10th gear and take off. It sucks and is hard to get up to a good cruising speed. Put it in 1st gear and you can get moving from a stop quickly and easily. (Thats why 4.10 was picked & not 2.14) But it sucks to go far fast as you will pedal your butt off and be panting like a **** quickly. The 10 speed is sort of like an overdrive transmission in that you can gear it to start out quickly and shift into higher gears per your needs ie how fast you want to go and whether you are going up or down a hill. What you have with the 4.10 & a th350 is like 1st gear on that 10 speed bike only you can't shift it up past say third so you still have to pedal very fast to go even just at a cruising speed. You can buy a simple indestructible single speed bike for cheap but a quality lightweight 10 speed bike might be worth the extra cost depending on how you are going to use that bike. You decide which is best depending on the money you have for your bike and how you are going to use it.
One more for you. Big blocks are large heavy strong men they don't like pedaling hard for long because their body says ima gona have a heart attach. The heart for an engine in this scenario is the rod & main bearings. Big blocks have big bearings. Big bearings make more heat than small bearings turning the same speed. (heat/wear kills) So you can ride your 4.10 geared big block down to Carlisle but I would not recommend doing it at 80 mph. Keep her at 55. She will still eat a lot of fuel and it will take longer to get there but she will get you there to tell about it and leave most other cars at the stop lights when you get their.
Fuel savings is a bonus by-product of an overdrive imo. Its all about keeping the engine healthy for a long time as you put lots of money into building one right. Oh yea on a 3 state interstate trip going 70 to 75mph my 509ci powered Cutlass got 17.0 mpg with a 3.42 where as with a 3 speed and the same gear she would have been lucky to get 12 mpg. I only put 9,000 miles on her before I sold her and I don't know if I saved enough gas money to pay for the extra cost of the overdrive but I know I didn't have to rebuild the engine. Hope that helps. BTW to help keep it alive & compensate for the heat of low gears & the 3 speed change your oil, transmission fluid, & rear end lube more often. Just check their color.
One more for you. Big blocks are large heavy strong men they don't like pedaling hard for long because their body says ima gona have a heart attach. The heart for an engine in this scenario is the rod & main bearings. Big blocks have big bearings. Big bearings make more heat than small bearings turning the same speed. (heat/wear kills) So you can ride your 4.10 geared big block down to Carlisle but I would not recommend doing it at 80 mph. Keep her at 55. She will still eat a lot of fuel and it will take longer to get there but she will get you there to tell about it and leave most other cars at the stop lights when you get their.
Fuel savings is a bonus by-product of an overdrive imo. Its all about keeping the engine healthy for a long time as you put lots of money into building one right. Oh yea on a 3 state interstate trip going 70 to 75mph my 509ci powered Cutlass got 17.0 mpg with a 3.42 where as with a 3 speed and the same gear she would have been lucky to get 12 mpg. I only put 9,000 miles on her before I sold her and I don't know if I saved enough gas money to pay for the extra cost of the overdrive but I know I didn't have to rebuild the engine. Hope that helps. BTW to help keep it alive & compensate for the heat of low gears & the 3 speed change your oil, transmission fluid, & rear end lube more often. Just check their color.
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