rx7speed

by head dispersion I'm assuming you mean heat? and your right the engine has more surface area on a v8 to disperse heat but that is bad. you lose efficiency by that. heat is energy. engines work by converting gas into heat. that heat then gets converted into mechanical energy. you start taking that heat out of the combustion proccess and into the cooling system you are wasting energy as it can't put pressure on the pistons. it also causes the above mentioned problem where you have more fuel that doesn't want to burn against the cylinder walls. still though remove that last one and the first problem is going to exist.

with the connecting rods your right in that maybe each connecting rod should be lighter then the I4 connecting rod but overall sum of parts the connecting rods should weigh more.

as far as torque/hp they should still produce eh about the same though the V8 might have a little flatter powerband though I don't know for sure on that one.

the rest though I more or less agree with. lots of variables and lots of things that can go on.

sorry if I'm comming of as a stubborn ahole it's cause I am . I just like a good debate ask anyone here who knows me sad thing is I think everyone else now is afraid to touch this thread but you and I. oh well it's fun

F-Body_Fetish

iTrader: (1)

Heat isnt whats pushing the piston down, well, not directly. when the gas ignites it expands, granted the hotter it is the more it will expand and the harder it will push down on the piston. however, if the same amount of heat is going to be absorbed by the block regardless you need to get rid of it. I'm actually really curious to find out about the gas igniting on the walls and the V8 having a higher surface area. I'm going to bore/stroke numbers and crunch them to see if the surface area is actually more. They may be equal, and if so it comes down to what burns the fuel better, the smaller or the larger combustion chambers/cylinders. And then if they burn them equally i think the V8 will have the advantage in terms of more power strokes, they'll be half as hard but twice as often, it will make more "fluid" power.

Maybe the extra weight of the conrods, journal bearings and whatnot won't add up to the added weight of extra balance shafts? maybe the difference is small its almost negligible?

Benny K

iTrader: (1)

BMW did this..but it was a 1.5 liter Inline 4 with turbocharger..and it made 1300bhp
the engine blocks were production iron blocks from standard BMW's (NO JOKE)..and they preferred blocks from used cars with about 100'000km's on them...

F-Body_Fetish

iTrader: (1)

Thats ridiculous, I wonder at what RPM's that thing made 1300 bhp. its probably light as **** too. Did it make 1300 on gasoline or methanol? I wonder what would happen if they stuck two of those blocks together to make a V8. Why don't they just put these tiny motors into cars? talk about fuel economy. perhaps they don't make the torque? or they're super expensive to make. I'm not saying drop a 1300hp motor into a car but still, 300 is enough you know? also, if you think about it. the Veyron is the fastest car at the moment (i don't know if the Chrysler ME Four-Twelve counts yet) but its only got 1001hp, if you dropped this motor in, which is like 1/6 the size it would go faster? it seems so surreal. Also, shouldn't we be able to get somewhere around 7000hp from a 8 liter V8? mind you I think power/displacement drops off as you increase displacement, although there is still power gain, its not as much per unit of displacement. meaning you would get more power/liter out of a 750cc I4 with a similar design (more than 650hp (half of 1300)).

Firebird_dave7

Yes rotary engines have power loss and can be realeased but the rotor is wat does all the work think of it this way if you go wide open with a rotary and with a V8 the rotary will turn higher rpms then the V8 but the rotary will burn up its rotor way faster the any of the 8 Cylinders, and V8's will still be around for years but I4's, V4's, and Rotary engines will be completely out of the market in probally 25yrs, the V8 is one of the most reliable engines to date along with few and i mean few I4's and I6's and V6 and i havent heard of a V4 that can go 40,000miles without a oil change.

rx7speed

dave in all honesty the highest reving engine I know is a v8 not a rotary. though granted it's use doesn't really relate to any street driven car. the rotary engine is very reliable as long as you know what your doing. even when abused. so far mine has about 220k miles on it and I have done nothing to the engine itself. no repairs no fixes no nothing to the egine. the closest thing I have done is cleaned the injectors (only reason I bring them up is they are bolted directly to the block) and replaced spark plugs and oil changes. granted I have done other work to the car but not the engine.
the other thing is I have yet really to see someone burn a rotor from hard use. closest I have seen is an apex seal break (equiv to a piston ring) or from someone way overboosting an engine and have the rotor collapse a little bit, but then again that was from over 20-25psi also.

as far as longevity goes in the market place so far v8's are more of a newcommer. I4's have been around for a while longer. The market trend has been going more to 4 cylinders then 8 cylinders so far. four cylinders have shown their reliability to be just as good as a four cylinder and in some ways maybe more so. many problems with 4 cylinder relability is not due to the 4 cylinder itself but due to the manufact not producing a quality product.

Then the last thing a bout a V4 going 40,000 miles without an oil change. what is that to prove? I'm sure many can go that far if you tried it's just that most people are not dumb enough to try it. only one I know of is myself and that was just because I didn't care about the car and drove it for about 2-3 years without changing the oil. but then again it leaked and I was wanting to see that car die anyway and it finally did though it put up the best fight I have ever seen.