Rx7 vs. 300zx
ALLJDM
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Well low and behold a friend of mine loaned her saturn to one of her girlfriends who has a 93 turbo rx7(yes the fast one) So she has ownership of the rx7 for about a week she kows I am into cars and i told her I wanted a ride in it to see if they realy are all that fast. As we are walking up to the car she hands me the keys
We are driving around the I-75 area and I decided to hop on the interstate from fowler and I goose this thing at first it felt slow and then at about 4500 rpm the damn turbo starts making boost and it just friggin launched. We blew bya 300 zx at about 120 ( no traffic and it was 3 lanes of roadway). I am pretty surprised at the midrange on the car and when I look in my rearview the damn 300zx is like friggin 1 off the damn bumper! So I keep inching foward to see if he wants some and I hammer it I absolutely walked his ass from about 65 through about 110(speed finds traffic) and I slow down to see if it was a turbo and sorry it wasnt...I was hoping for a good race its no fun beating a car that you know is slow. Ah well me thinks I would not mind owning a last gen rx7. No low end power to speak of though but still quite fun I managed to get it up to about 130.
We are driving around the I-75 area and I decided to hop on the interstate from fowler and I goose this thing at first it felt slow and then at about 4500 rpm the damn turbo starts making boost and it just friggin launched. We blew bya 300 zx at about 120 ( no traffic and it was 3 lanes of roadway). I am pretty surprised at the midrange on the car and when I look in my rearview the damn 300zx is like friggin 1 off the damn bumper! So I keep inching foward to see if he wants some and I hammer it I absolutely walked his ass from about 65 through about 110(speed finds traffic) and I slow down to see if it was a turbo and sorry it wasnt...I was hoping for a good race its no fun beating a car that you know is slow. Ah well me thinks I would not mind owning a last gen rx7. No low end power to speak of though but still quite fun I managed to get it up to about 130.
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Sweet. Ive been wondering about the Turbo RX7s lately. I had been figuring there must be a reason their owners put up with the obnoxious cat being beaten with a sock full of quarters sound that emits from the tail pipe. Very impressive. Also interesting how the cars are what 1.3L? yet produce exhaust gasses as a 3.0L V6. Always wondered how in the world they get the huge turbos to even rotate on that lawnmower size engine. Very impressive. I dont think I could handle driving a NA RX7 though. How true are all the tales of fragile Apex seals and one bit of detonation and the motor is done?
/me goes off to research RX7s....
/me goes off to research RX7s....
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Too be honest the thing actually sounds pretty cool it has some kind of friggin 4 exhaust all the way back but those rotaries sound friggin awsome when they are a turbo version absolutely nuthin like a mexi-rotary. Hey boosted whatcha got done to your 300zx? I have always liked those cars as long as they are the twin turbo the n/as suck. The only thing is that they have like no roojm to work on the damn engine. Well the rx7 has 72 friggin vaccum ports so easy to see but imagine crossing two...BOOM probably. Yes I have heard the rumors about the seals but this one has 100k on it with no probs she said it used to be ALOT faster the lose a serious amount of power when the seals get worn but I still want one hell the damn engine probably weighs like 150lbs Ill just yank the sumbitch myself.
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Blah from the factory i think the Rexies came with 2mm Apex Seals which afer hard driving heated up and cracked....Causing vacuum leaks. All you have to do is replace the 2mm seal with 3mm seal and check them every once in a while. Then you should have any problems. One of the biggest things you can do to increase the performance of a rotary engine is add a free flowing exhaust and cats. This is a major choke point for these motors and I have seen 30+ horses just from adding an entire exhaust.
Long post ugh.
Long post ugh.
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Dont run it lean and you wont blow apex seals. As far as the motor being light They are not. A friend and I lifted an older 1.2l Rotory motor and it was a real bitch. Weighed as much as a 1.5l toyota motor we lifted recently. The toyota 4cyl had the intake and exhaust manifolds on it the rotory was bare.
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How about two pennies from a happy owner
The first turbo on the 3rd gens starts boosting at about 2500 or so RPM (depending on exhaust intake and cats). Its a tiny turbo though so it doesnt quite have the kick. At around 4500 the first turbo stops and it switches over the 2nd (slightly larger) turbo. The system Mazda uses to do this uses about 65 vacuum hoses and about 12 solenoids. Its a BIG pain. Many owners convert to a non-sequential setup giving boost from about 3500+ RPM and only 5 hoses. A single turbo setup also works well. They arent easy to launch either but then it wasnt designed to be a drag car.
The whole 1.3L thing..... well thats true but to quote from an FAQ:
Rotaries are very reliable if you take care of them. Like any high-revving high HP engine it needs fresh oil good gas and maintenance. Its not rocket science or anything the big reason they got such a bad rep is that its not a motor you can just ignore oil changes with or run hard when cold etc. 100k miles is not uncommon and is a lot to ask of any performance car RX-7 or not.
And about the 2mm apex seals.. I have never heard of them getting hard and cracking after hard driving. Its not uncommon to get 400+HP with 2mm seals what kills them is detonation. Rotaries cant handle very much detonation before the seal exits via the exhaust. But a well tuned engine (piston or rotary) wont detonate. In fact its been argued that 3mm seals increase the surface area of the seal too much making the stock oil metering pump inadequate for lubrication. The oil metering system injects crank case oil directly into the combustion chamber to lubricate the seals and cool the engine.
Well this is probably too long but I figure only those who are interested will read it anyway.
-j0lt
The first turbo on the 3rd gens starts boosting at about 2500 or so RPM (depending on exhaust intake and cats). Its a tiny turbo though so it doesnt quite have the kick. At around 4500 the first turbo stops and it switches over the 2nd (slightly larger) turbo. The system Mazda uses to do this uses about 65 vacuum hoses and about 12 solenoids. Its a BIG pain. Many owners convert to a non-sequential setup giving boost from about 3500+ RPM and only 5 hoses. A single turbo setup also works well. They arent easy to launch either but then it wasnt designed to be a drag car.
The whole 1.3L thing..... well thats true but to quote from an FAQ:
Originally posted by "Someone"
Rotary engine displacements seem small when compared to piston engines of similar power. In fact both displacements are measured the same way. Displacement is the sum total of positive combustion chamber volume increases for one complete revolution of the main shaft (crank or eccentric). In a piston engine this means the total amount of space swept by its pistons. In a rotary it is easiest to think about the difference between the maximum and minimum volumes for a single chamber multiplied by the number of rotors (where each rotor has 3 chambers). Remember that the rotor actually revolves at one third the speed of the eccentric shaft which is the reason only one chambers displacement is used in the calculation. The difference in power is due to the fact that the rotary uses its full displacement to produce power for each revolution of the eccentric shaft while only half the displacement of the piston engine is producing power for each revolution of the crankshaft. Other differences also play a role; rotaries do not have the losses of reciprocating motion and there is no valve train to power.
Rotary engine displacements seem small when compared to piston engines of similar power. In fact both displacements are measured the same way. Displacement is the sum total of positive combustion chamber volume increases for one complete revolution of the main shaft (crank or eccentric). In a piston engine this means the total amount of space swept by its pistons. In a rotary it is easiest to think about the difference between the maximum and minimum volumes for a single chamber multiplied by the number of rotors (where each rotor has 3 chambers). Remember that the rotor actually revolves at one third the speed of the eccentric shaft which is the reason only one chambers displacement is used in the calculation. The difference in power is due to the fact that the rotary uses its full displacement to produce power for each revolution of the eccentric shaft while only half the displacement of the piston engine is producing power for each revolution of the crankshaft. Other differences also play a role; rotaries do not have the losses of reciprocating motion and there is no valve train to power.
And about the 2mm apex seals.. I have never heard of them getting hard and cracking after hard driving. Its not uncommon to get 400+HP with 2mm seals what kills them is detonation. Rotaries cant handle very much detonation before the seal exits via the exhaust. But a well tuned engine (piston or rotary) wont detonate. In fact its been argued that 3mm seals increase the surface area of the seal too much making the stock oil metering pump inadequate for lubrication. The oil metering system injects crank case oil directly into the combustion chamber to lubricate the seals and cool the engine.
Well this is probably too long but I figure only those who are interested will read it anyway.
-j0lt
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I reckon its a moot point being that a 93 rx7 still fetches close to 20 friggin grand. I do like the concept of a rotary though and I appreciate the technical readings posted here. But being as that I am getting a dsm...ah well another moot pointand yes the car had full exhaust and I will never get to drive it agian becuase the girl had to give it back to her friend.
