Honest opinion on why I chose the V8 after being a long time rotary guy.
11-26-15, 11:38 AM
#51
Valley, how far do you want to take this argument? No one has said it is any lighter. You could make a tube frame GT1 car with an RX7 body if you WANTED to. If you have the funds and the time anyone can do whatever they want, that is the beauty of hot rodding. If you want to argue this down the the last ounce go ahead. Yes the rotary drivetrain is lighter on its face. No one is arguing that. If you are building a street car, you don't care about a few extra pounds anyway. If you are building a race car, you will still need to add ballast to make weight (or power to weight) for most road racing classes. For drag racing, keep it a rotary if you like it so much, or keep your heavier v8 and spray it with a 100 shot to make up for the weight difference.
If you arent happy with your v8 then put the rotary back in. If you buy ANY engine from a junkyard you should at least inspect it and possibly rebuild it. That is not unique to V8s. That said if you get a junkyard engine and it passes a compression and leakdown test and the oil looks good with no external leaks, it is probably a good bet it will run ok.
I bought a hurt LS1 engine for my swap because it was a deal I could not pass up, and I did not see paying a premium for a running engine when I was going to pull it apart to upgrade it.
But as you said, I'm somehow "lucky" that my engine has held together. It's not as if it was professionally built and assembled for my specific use case.
I put a v8 in the car because it was cheaper in the long run than building a turbo rotary drivetrain the way I wanted one built. I'm saving hundreds of dollars on fuel alone every track day because I can run 91 instead of race gas. I run 10-12 track days a year and use about 30 gallons of fuel per day.
If you are talking about rebuilding and upgrading the entire drivetrain in the car with with either turbo rotary power or V8 power the costs can be pretty close with careful planning and smart purchases. I'm talking, rebuilt trans, rebuilt and upgraded rear end, and built turbo engine or equivalent power V8. I am not talking about a run of the mill drop in swap someone would
run on the street. My entire drivetrain had 0 miles when I started the car for the first time. Everything was new or rebuilt. I'd be happy to share costs and compare them with someone that did the same thing with their rotary powered car.
Considering that, all in the V8 will likely be more money, but you are saving money on consumables like fuel. If you pop a rotary, you'll be in for more than the V8 after you rebuild it once.
I'm not saying all rotaries blow up, but I don't know what the rebuild or refresh cycle on a high performance rotary looks like, or what it costs to do that preventative maintenance every X number of hours or miles.
If you arent happy with your v8 then put the rotary back in. If you buy ANY engine from a junkyard you should at least inspect it and possibly rebuild it. That is not unique to V8s. That said if you get a junkyard engine and it passes a compression and leakdown test and the oil looks good with no external leaks, it is probably a good bet it will run ok.
I bought a hurt LS1 engine for my swap because it was a deal I could not pass up, and I did not see paying a premium for a running engine when I was going to pull it apart to upgrade it.
But as you said, I'm somehow "lucky" that my engine has held together. It's not as if it was professionally built and assembled for my specific use case.
I put a v8 in the car because it was cheaper in the long run than building a turbo rotary drivetrain the way I wanted one built. I'm saving hundreds of dollars on fuel alone every track day because I can run 91 instead of race gas. I run 10-12 track days a year and use about 30 gallons of fuel per day.
If you are talking about rebuilding and upgrading the entire drivetrain in the car with with either turbo rotary power or V8 power the costs can be pretty close with careful planning and smart purchases. I'm talking, rebuilt trans, rebuilt and upgraded rear end, and built turbo engine or equivalent power V8. I am not talking about a run of the mill drop in swap someone would
run on the street. My entire drivetrain had 0 miles when I started the car for the first time. Everything was new or rebuilt. I'd be happy to share costs and compare them with someone that did the same thing with their rotary powered car.
Considering that, all in the V8 will likely be more money, but you are saving money on consumables like fuel. If you pop a rotary, you'll be in for more than the V8 after you rebuild it once.
I'm not saying all rotaries blow up, but I don't know what the rebuild or refresh cycle on a high performance rotary looks like, or what it costs to do that preventative maintenance every X number of hours or miles.
Last edited by LargeOrangeFont; 11-26-15 at 11:56 AM.
11-26-15, 02:57 PM
#52
My whole point is about weight. Yes, you and I have brought in other things in this. But, you are arguing that the weight is a negligible difference. I am stating that it is not and that your numbers are not even close to as apples-to-apples as the comparison can get. This isn't about me, my car, your car, or anything else except that the numbers you and others with the swap post do not tell the whole story and is inherently misleading when posted.
Yes, we could go into a tube frame car, and assuming the only differences was the drive train it would still be more than 20lbs or 50lbs difference. That was the point of my bringing my car into it. I could feasibly and realistically "simply" change out the engine and I would expect to see the difference in weight would be the difference in weight between the engines.
I am aware of how much more money, in fuel alone, that turbo cars tend to require. I've known people that swapped an inherently worse motor into their track car simply to save gas money. Fair enough, but they don't say or imply that it is lighter or faster or that either is negligible when it isn't. 120lbs (just engine) on a 2500lbs car (assuming a prepped FC) is close to 5%; which is not negligible. Frankly, I wouldn't consider the equivalent of a small passenger constantly with you to be negligible regardless of the weight.
We both know there are a lot of reasons to perform the swap. Hell, I did the swap. But this weight thing really gets my goat.
Yes, we could go into a tube frame car, and assuming the only differences was the drive train it would still be more than 20lbs or 50lbs difference. That was the point of my bringing my car into it. I could feasibly and realistically "simply" change out the engine and I would expect to see the difference in weight would be the difference in weight between the engines.
I am aware of how much more money, in fuel alone, that turbo cars tend to require. I've known people that swapped an inherently worse motor into their track car simply to save gas money. Fair enough, but they don't say or imply that it is lighter or faster or that either is negligible when it isn't. 120lbs (just engine) on a 2500lbs car (assuming a prepped FC) is close to 5%; which is not negligible. Frankly, I wouldn't consider the equivalent of a small passenger constantly with you to be negligible regardless of the weight.
We both know there are a lot of reasons to perform the swap. Hell, I did the swap. But this weight thing really gets my goat.
11-26-15, 03:27 PM
#53
There is nothing misleading about this, I don't know why you keep insisting that people's results are invalid. These weight differences are on a case by case basis. You can't dismiss people's results when every car and setup is different. The lightest possible weight you can theoretically make the car is irrelevant to the conversation, unless you are specifically trying to do that. This is an engine swap and the only weight that really matters is what someone's car weighs before and after. There are more factors to consider other than weight. 99.9% of the drivers on this forum are not going to notice 50lbs or even 100 lbs on the track. I sure as hell don't. This is not NASCAR where 50 lbs represents a huge change in performance and we are all paid professional drivers. I'm not saying there is no total performance difference. I'm saying you and I are not good enough to notice or care.
If what you said is true, my car should be slower because I added weight, yet it is over 15 seconds faster around a 2 mile course.
I'll say again, my "heavier" car that is down 50+ hp with smaller tires and no aero is about a second slower around a 2 mile course. The weight is not the reason the car is slower. Equalize any one of those variables (aero, power or tire) and we would be damn near even. Equalize all of them aside from weight, and I could have them covered. But there I go cherry picking results again.
Again, show me where anyone has said anything misrepresenting that the V8 swap will probably add weight in most cases.
If what you said is true, my car should be slower because I added weight, yet it is over 15 seconds faster around a 2 mile course.
I'll say again, my "heavier" car that is down 50+ hp with smaller tires and no aero is about a second slower around a 2 mile course. The weight is not the reason the car is slower. Equalize any one of those variables (aero, power or tire) and we would be damn near even. Equalize all of them aside from weight, and I could have them covered. But there I go cherry picking results again.
Again, show me where anyone has said anything misrepresenting that the V8 swap will probably add weight in most cases.
Last edited by LargeOrangeFont; 11-26-15 at 03:37 PM.
11-26-15, 04:33 PM
#54
Assuming that the same modifications are done there is no probably. This means lightweight flywheel to lightweight flywheel. PS removal to PS removal. Subframe to subframe. Exhaust to exhaust. CF hood to CF hood. Etc.
I have yet to see or hear of a swap that did this one to one. Many remove or change one or more subsystem from the car during a swap that they retained or didn't change before the swap for a variety of reasons. This is why the weight differences often quoted aren't larger.
Without understanding this it gives the general person, and many who have done the swap, the impression that there isn't as much of a weight difference between both the engine and trans. And there is. Hence it being misleading.
I have yet to see or hear of a swap that did this one to one. Many remove or change one or more subsystem from the car during a swap that they retained or didn't change before the swap for a variety of reasons. This is why the weight differences often quoted aren't larger.
Without understanding this it gives the general person, and many who have done the swap, the impression that there isn't as much of a weight difference between both the engine and trans. And there is. Hence it being misleading.
11-26-15, 05:02 PM
#55
Do you somehow feel you were sold a bill of goods? Simple research on NoRotors and the internet at large would have netted you or anyone else knowledge that a 1to1 swap could make your car a bit heavier, and you can also do some other things at the same time to mitigate the weight penalty. I'd trade the weight, efficiency, simplicity, durability and the flat torque curve for the weight penalty any day. Weight is very important, but it is not the only factor to consider.
If you do the swap you do are doing it whatever reasons you have chosen. I have not seen anyone besides you analyzing the swap saying "If I had stayed rotary my car would be lighter". Of everyone I know their car is faster AFTER the swap, regardless of weight. If that is a product of them installing an engine with more horsepower, it is what it is.
Again, I can't think of anyone I have seen that has regretted the swap or says their car is somehow slower, that includes road racers and drag racers, so take that for what it's worth. If you don't like your swap for some reason you'd be in the company of very few, if not alone.
That is not to say a V8 swap is mandatory, or the only way to go. I frankly don't care what others do to their car, but the more power you want to make, the more a V8 starts makes sense.
If you do the swap you do are doing it whatever reasons you have chosen. I have not seen anyone besides you analyzing the swap saying "If I had stayed rotary my car would be lighter". Of everyone I know their car is faster AFTER the swap, regardless of weight. If that is a product of them installing an engine with more horsepower, it is what it is.
Again, I can't think of anyone I have seen that has regretted the swap or says their car is somehow slower, that includes road racers and drag racers, so take that for what it's worth. If you don't like your swap for some reason you'd be in the company of very few, if not alone.
That is not to say a V8 swap is mandatory, or the only way to go. I frankly don't care what others do to their car, but the more power you want to make, the more a V8 starts makes sense.
Last edited by LargeOrangeFont; 11-26-15 at 05:07 PM.
11-26-15, 05:09 PM
#56
Full Member
Weight aside, the Ls swap is just practical. That's the main reason I am doing it on my car. I had a rotary setup that would be reliable (haltech, vmount, no emissions, single turbo etc), but I would have still had the issue of premixing, worrying about the tune being spot on with pump gas, worrying about transmission issues above 450-500whp, and just general tinkering inherent with a 450-500whp small motor turbo car. For me, I want a car that I can drive across the country and not worry about the quality of the gas I'm getting whatsoever. Something that I don't have to monitor afr to make sure everything is still looking good. With the Ls you just don't have any worries as long as you do everything right the first time imo. This can be true for rotaries too, but in my case I am having a child next year and I am swapping this winter to prevent having any worries during the first few years of my child's life. I can just get in the car and drive. Yes, much like a corvette...but if I wanted a corvette I would have bought one, the FD is much more unique.
Additionally, I can have some input on weight after the swap is complete on my car. My FD weighed 2600 without ac/power steering, emissions, etc. The Ls will be the same as far as accessories go at first until I get the ac figured out.
Additionally, I can have some input on weight after the swap is complete on my car. My FD weighed 2600 without ac/power steering, emissions, etc. The Ls will be the same as far as accessories go at first until I get the ac figured out.
11-26-15, 05:52 PM
#57
LOF, ~170lbs (engine & trans) is not a little bit. Again, this isn't about me. If you read the post in my build thread where I talk about addressing weight it is easily understood that I knew exactly what I was getting into.
And no, reading norotors, which I had done extensively leading up to my swap, does not give a clear answer except to say exactly what you say, that it's negligible when it isn't. Yes, the LS has, in some regards, more easily attained "potential" for power. No, the swap is not inherently faster depending on what you started with.
I apparently cannot say this enough. This is not about me or my swap. Please stop insinuating such. This is about providing a factual counter point to the general misinformation that swap guys spread about weight.
Let me put it to you this way. Say I get a 13bt tomorrow and to "prove" my point I swap the engine in my car and take pre and post swap weight measurements. Lets say I also swapped to a custom lithium/supercap hybrid battery at the same time and changed back to the non-auto starter and didn't disclose or even mention or hint at these changes and said "look at how much lighter it is!" You would, I think very obviously, call me out on those changes. Same thing applies here.
Dye, I would be very interested in your post swap weight when you finish. Please do note which swap kit you use and gas tank fill.
And no, reading norotors, which I had done extensively leading up to my swap, does not give a clear answer except to say exactly what you say, that it's negligible when it isn't. Yes, the LS has, in some regards, more easily attained "potential" for power. No, the swap is not inherently faster depending on what you started with.
I apparently cannot say this enough. This is not about me or my swap. Please stop insinuating such. This is about providing a factual counter point to the general misinformation that swap guys spread about weight.
Let me put it to you this way. Say I get a 13bt tomorrow and to "prove" my point I swap the engine in my car and take pre and post swap weight measurements. Lets say I also swapped to a custom lithium/supercap hybrid battery at the same time and changed back to the non-auto starter and didn't disclose or even mention or hint at these changes and said "look at how much lighter it is!" You would, I think very obviously, call me out on those changes. Same thing applies here.
Dye, I would be very interested in your post swap weight when you finish. Please do note which swap kit you use and gas tank fill.
11-26-15, 06:37 PM
#58
I'll ask this another way.. What does the weight matter if the car performs better in every demonstrable aspect of performance? The answer is that the weight does not matter.
A TurboII FC is heavier than a Base NA FC. The TurboII does everything faster, and yet is heavier. From a performance perspective, the TurboII is a better car. By your logic are you saying the the NA car will somehow perform better?
I was trying to give you the benefit of the doubt earlier by assuming both engines had the same power, but when doing these swaps that is typically not the case. Generally people swap in engines that have more power than the rotaries they replaced, and erase any benefit that the lighter weight could have afforded. Even a stock 5.3 300HP truck engine is enough to handily outperform a 13bt, even with the maximum amount of extra weight.
If I weigh 150 more pounds than you, I need just under 50 more HP than you to keep the power to weight in my favor. If you want to start playing tit for tat mod game, have at it. I can easily add another 150 HP to a 5.3 truck engine for no extra weight gain. You'll have to more than double the output of your 13bt to hang.
A TurboII FC is heavier than a Base NA FC. The TurboII does everything faster, and yet is heavier. From a performance perspective, the TurboII is a better car. By your logic are you saying the the NA car will somehow perform better?
I was trying to give you the benefit of the doubt earlier by assuming both engines had the same power, but when doing these swaps that is typically not the case. Generally people swap in engines that have more power than the rotaries they replaced, and erase any benefit that the lighter weight could have afforded. Even a stock 5.3 300HP truck engine is enough to handily outperform a 13bt, even with the maximum amount of extra weight.
If I weigh 150 more pounds than you, I need just under 50 more HP than you to keep the power to weight in my favor. If you want to start playing tit for tat mod game, have at it. I can easily add another 150 HP to a 5.3 truck engine for no extra weight gain. You'll have to more than double the output of your 13bt to hang.
Last edited by LargeOrangeFont; 11-26-15 at 07:08 PM.
11-26-15, 08:04 PM
#59
You honestly think a 300hp iron block truck engine that would add somewhere around 250 or 300lbs (including t56) on the front of a car is going to out perform the same car with 300hp but without the weight penalty? Or do you think that 300hp is not attainable by a 13bt? The questions are rhetorical.
Nice troll I suppose, you certainly had me going there for a while, but I'm done.
Nice troll I suppose, you certainly had me going there for a while, but I'm done.
11-26-15, 08:28 PM
#60
Modern truck engine.. I said 300 HP truck 5.3, not the lower HP variants with iron blocks. Most of the 5.3s made after 06 are aluminium block, and are of the HO variety (flat top high compression pistons, and cylinder head castings off of the LS6/LS2 corvette engines). Yes they are not $500 from a junkyard, they are more like $900-$1000. Small price to pay to keep an aluminium block.
I know a 13bt is capable of 300 HP. Just like the truck engine is capable of 450 HP with a simple cam and head swap. Like I said, I can easily stay 50 HP up on you until one of the powertrains explode.
Thank you for playing!
I know a 13bt is capable of 300 HP. Just like the truck engine is capable of 450 HP with a simple cam and head swap. Like I said, I can easily stay 50 HP up on you until one of the powertrains explode.
Thank you for playing!
11-26-15, 10:21 PM
#61
Senior Member
Is an LS swap heavier? Yeah, like vs. like, it's ~50 lb. heavier in an FD vs. stock. See L.O.F.'s post with my weights on page 1. Plenty of info on these swaps, you just have to pay close attention to equipment and fuel on board. 50 lb. is pretty much the norm for like vs. like LS vs. stock FD.
2% weight gain, OMG...
2% weight gain, OMG...
11-27-15, 12:40 AM
#62
Retired Moderator, RIP
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You know it's a battle of Piston guys against Rotorheads..and really I am surprised that nobody has come out with the comment that you can have the best of both worlds when you do a swap.So really every one is a winner.
Sure you can run Tacos..you can run Boinger..but when you combine the V8 and the FC?..or an FD?..you get a Freakin Decent car no matter how you slice it.
You got the agility of the car(as it was before hand) but also the proven piston engine platform.
Sure you can run Tacos..you can run Boinger..but when you combine the V8 and the FC?..or an FD?..you get a Freakin Decent car no matter how you slice it.
You got the agility of the car(as it was before hand) but also the proven piston engine platform.
11-27-15, 08:06 AM
#63
You know it's a battle of Piston guys against Rotorheads..and really I am surprised that nobody has come out with the comment that you can have the best of both worlds when you do a swap.So really every one is a winner.
Sure you can run Tacos..you can run Boinger..but when you combine the V8 and the FC?..or an FD?..you get a Freakin Decent car no matter how you slice it.
You got the agility of the car(as it was before hand) but also the proven piston engine platform.
Sure you can run Tacos..you can run Boinger..but when you combine the V8 and the FC?..or an FD?..you get a Freakin Decent car no matter how you slice it.
You got the agility of the car(as it was before hand) but also the proven piston engine platform.
11-27-15, 11:28 AM
#64
If you believe a rotary is more reliable than a LS v8 engine I'll let you continue to live in your fantasy land. Don't bother to look how many RX8s with 60-100k miles that have blown rotaries or are on their second engine.
We are not talking about a stock 13bt. If you want a 200 HP car, keep your rotary. Yes it is lighter than a V8. If you want a 400-500 HP of rotary power you are ADDING weight to do it. After adding dual oil coolers, front mount intercooler, larger turbo, wastegate, etc you are within 50 lbs of a fully dressed LS1. If you aren't running AC or PS on an LS1 the weight drops 25-30 lbs. If you run an aluminium flywheel, it takes off another 30 lbs, but you can also do that on the 13bt.
Even if it does weigh a bit more it clearly works, and does not upset the balance of the car.
We are not talking about a stock 13bt. If you want a 200 HP car, keep your rotary. Yes it is lighter than a V8. If you want a 400-500 HP of rotary power you are ADDING weight to do it. After adding dual oil coolers, front mount intercooler, larger turbo, wastegate, etc you are within 50 lbs of a fully dressed LS1. If you aren't running AC or PS on an LS1 the weight drops 25-30 lbs. If you run an aluminium flywheel, it takes off another 30 lbs, but you can also do that on the 13bt.
Even if it does weigh a bit more it clearly works, and does not upset the balance of the car.
MY FD with stock Twins . and AC/Power steering weighs 2700lbs 3/4 tank (I dont have a baffle so I always race with 3/4 tank to keep from fuel starving )
and and a 49F / 51 R weight distribution .
I recognize that the LS is a reliable workhorse and i'm sure it increases the MPGs
but I love my car's character and dont want to trade it for corvette ishness of the LS swap.
11-27-15, 12:19 PM
#65
Senior Member
You want torque, an [unmodified] RX7 is not the car for you.
You want to drag race, buy a Mustang or Camaro.
. The RX7 is an exotic car,
That shouldn't annoy you at all! Ideal weight distribution for a highish power/weight rear-drive car is going to be rear-biased. This is a (minor) legitimate drawback to LS/T56 swap, weight distribution moves forward by about 1.5% vs. stock FD. My car is just barely rearward of 50/50 with me in it and 3/4 tank. I'd much rather have it at 45/55...
Last edited by ZDan; 11-27-15 at 12:24 PM.
11-27-15, 12:48 PM
#66
I have nothing against LS swaps . i've considered it multiple times But I do know my car is quite lightj and I love the way it drives .. I have friends with V8 Fd's and they are a hand full all that low end torque
MY FD with stock Twins . and AC/Power steering weighs 2700lbs 3/4 tank (I dont have a baffle so I always race with 3/4 tank to keep from fuel starving )
and and a 49F / 51 R weight distribution .
I recognize that the LS is a reliable workhorse and i'm sure it increases the MPGs
but I love my car's character and dont want to trade it for corvette ishness of the LS swap.
MY FD with stock Twins . and AC/Power steering weighs 2700lbs 3/4 tank (I dont have a baffle so I always race with 3/4 tank to keep from fuel starving )
and and a 49F / 51 R weight distribution .
I recognize that the LS is a reliable workhorse and i'm sure it increases the MPGs
but I love my car's character and dont want to trade it for corvette ishness of the LS swap.
My FC (and FDs to a greater extent) drives like a lighter, more raw Vette. They simply don't build cars that drive like an RX7 with a lot of horsepower. I have a feeling it is similar to driving a 427 Cobra back in the day given the explosive and raw feel of the car
11-27-15, 04:59 PM
#67
Just to be sure we're on the same page, we have two idealized cars with the same hp but one is lighter than the other. Which is faster?
Too easy! The one with the better driver.
Bottom line is if you like V8 any resulting added weight is going to be worth it or worked on to eliminate.
If you hate V8 any added weight is an(other) excuse not to swap.
You could easily do a V8 swap and lose weight (even up front) there are so many variables.
A lot of time people that love V8s hate ABS for instance, or hate AC or hate fat passengers, or love race seats or love 4lb batteries.
Too easy! The one with the better driver.
Bottom line is if you like V8 any resulting added weight is going to be worth it or worked on to eliminate.
If you hate V8 any added weight is an(other) excuse not to swap.
You could easily do a V8 swap and lose weight (even up front) there are so many variables.
A lot of time people that love V8s hate ABS for instance, or hate AC or hate fat passengers, or love race seats or love 4lb batteries.
11-28-15, 08:59 AM
#68
all things must be created equal in a comparison though, can't say a V8 can be lighter if you give the V8 the advantage of a micro battery but keep a full size lead acid in the rotary counterpart.
the V8 has the advantage of a flat power curve from bottom to top where the rotary has no bottom, however it has a longer RPM range to use which is what allows it to keep up and in many cases to outrun an equal power piston engine. but boingers have matched and even succeeded the rotary in RPMs, the V8 will not be an exception soon.
back in the day the RPMs were what gave rotaries a serious edge, you had to go all out on a piston engine for it to run 9k RPMs but these days everything is lightened and more balanced so those numbers are not even impressive any longer. when i first drove an RX7 i was impressed by how smooth and effortless it ran up through the RPM range, seemingly wanting more.
the V8 has the advantage of a flat power curve from bottom to top where the rotary has no bottom, however it has a longer RPM range to use which is what allows it to keep up and in many cases to outrun an equal power piston engine. but boingers have matched and even succeeded the rotary in RPMs, the V8 will not be an exception soon.
back in the day the RPMs were what gave rotaries a serious edge, you had to go all out on a piston engine for it to run 9k RPMs but these days everything is lightened and more balanced so those numbers are not even impressive any longer. when i first drove an RX7 i was impressed by how smooth and effortless it ran up through the RPM range, seemingly wanting more.
Last edited by RotaryEvolution; 11-28-15 at 09:05 AM.
11-28-15, 10:06 AM
#69
all things must be created equal in a comparison though, can't say a V8 can be lighter if you give the V8 the advantage of a micro battery but keep a full size lead acid in the rotary counterpart.
the V8 has the advantage of a flat power curve from bottom to top where the rotary has no bottom, however it has a longer RPM range to use which is what allows it to keep up and in many cases to outrun an equal power piston engine. but boingers have matched and even succeeded the rotary in RPMs, the V8 will not be an exception soon.
back in the day the RPMs were what gave rotaries a serious edge, you had to go all out on a piston engine for it to run 9k RPMs but these days everything is lightened and more balanced so those numbers are not even impressive any longer. when i first drove an RX7 i was impressed by how smooth and effortless it ran up through the RPM range, seemingly wanting more.
the V8 has the advantage of a flat power curve from bottom to top where the rotary has no bottom, however it has a longer RPM range to use which is what allows it to keep up and in many cases to outrun an equal power piston engine. but boingers have matched and even succeeded the rotary in RPMs, the V8 will not be an exception soon.
back in the day the RPMs were what gave rotaries a serious edge, you had to go all out on a piston engine for it to run 9k RPMs but these days everything is lightened and more balanced so those numbers are not even impressive any longer. when i first drove an RX7 i was impressed by how smooth and effortless it ran up through the RPM range, seemingly wanting more.
But relative to your own personal swap, you can mitigate the weight penalty on your own car pretty easily as we have talked about. I did this as I had nearly the lightest factory FC configuration to start with. I'm less than 100lbs heavier than the advertised ~2500# curb weight. I've pulled stuff out but added a ton of stuff too.
Last edited by LargeOrangeFont; 11-28-15 at 10:10 AM.
11-28-15, 10:39 AM
#70
it all boils down to a bit of luck, experience and the ability to work on the car. V8's are by no means indestructable either, in fact they really can't manage to spin up to redline and hold there as long as a rotary can.
its actually the transient loads and the fragility of the rotary in terms of tuning are what cause most failures, they are the least forgiving of anything short of turbocharging a yugo. the benefit of learning how to build one is the mittens you wear when building and setting up an engine, where others are more forgiving giving you better refining skills.
and yes, luck does play a role in building an RX7. there have been cases i caught issues with parts when stressing them that were failures beyond my control. issues that cause threads like this to spawn.
its actually the transient loads and the fragility of the rotary in terms of tuning are what cause most failures, they are the least forgiving of anything short of turbocharging a yugo. the benefit of learning how to build one is the mittens you wear when building and setting up an engine, where others are more forgiving giving you better refining skills.
and yes, luck does play a role in building an RX7. there have been cases i caught issues with parts when stressing them that were failures beyond my control. issues that cause threads like this to spawn.
Last edited by RotaryEvolution; 11-28-15 at 10:46 AM.
11-28-15, 11:01 AM
#71
Well luck helps when modifying anything. That and some common sense go a long way. I try to shift at 6500-6600 but the engine is built to to be safe to 7000. I use that extra RPM if it is faster to keep the car in gear just a little longer before a particular corner.
I also run a mild cam by today's standards, so it is very easy on the valvetrain. For heavy track use there are some durability mods you want to do to an LS based engine. Typically those are better valve springs and pushrods, upgraded rocker trunions, and upgraded connecting rod bolts. Also an upgraded oil pan baffle is a great idea. If you change the cam there are a couple other "while you are there" upgrades as well. All of that stuff will be added insurance against oil or valvetrain related failures.
If you are building a street car, or occasional track car you don't have to do any of that. On a junkyard engine a fresh set of valve springs might be a good idea. You are probably going to drive your swapped RX7 harder than the vehicle the engine came out of, so it should be given a through once over
I also run a mild cam by today's standards, so it is very easy on the valvetrain. For heavy track use there are some durability mods you want to do to an LS based engine. Typically those are better valve springs and pushrods, upgraded rocker trunions, and upgraded connecting rod bolts. Also an upgraded oil pan baffle is a great idea. If you change the cam there are a couple other "while you are there" upgrades as well. All of that stuff will be added insurance against oil or valvetrain related failures.
If you are building a street car, or occasional track car you don't have to do any of that. On a junkyard engine a fresh set of valve springs might be a good idea. You are probably going to drive your swapped RX7 harder than the vehicle the engine came out of, so it should be given a through once over
Last edited by LargeOrangeFont; 11-28-15 at 11:06 AM.
11-28-15, 11:29 AM
#72
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V8 swaps
I'm not against the v8 swaps. I once had a 358WHP Monster miata. Small, light, and went really well. After the Miata i bought a 1987 Porsche 944T. I did some mods and got a very reliable 326 wheel hp at 17 psi. Porsche was a far superior car. My question to the FC v8 swap guys - Why aren't you guys swapping in the LS motors into the 944t's? (I know people have) Just curious. They have (over the rx7):
Better braking
better weight distribution (transaxle in rear)
can fit wider tires
better road feeling/cornering
Look very similar
I currently own an 88 Turbo 10AE rx7. Love the car but if I were to do the V8 swap it would be the 944T. Sorry if the pics are flipped.
Any thoughts?
Better braking
better weight distribution (transaxle in rear)
can fit wider tires
better road feeling/cornering
Look very similar
I currently own an 88 Turbo 10AE rx7. Love the car but if I were to do the V8 swap it would be the 944T. Sorry if the pics are flipped.
Any thoughts?
11-28-15, 12:03 PM
#73
This got hilarious over this past week. I find the hate for the V8 swaps to come from two places: 1. People who could never afford a nice FD, let alone to buy one and do a quality swap. 2. Rotary owners with insecurities or people with crap cars. I have never had someone with a nice rotary FD bash my car or tell me I ruined it, we both have nice cars and can appreciate what the differences are, especially on high quality builds. The people who will have something to say in real life are typically driving a 20 year old Miata that is slammed with a crappy paint job or an RX-8 that they wish was an FD. The whole point of the 90's and up Japanese car scene is to modify your car and make it your own. I can very much appreciate a nice rotary car because I am confident and happy with me and my car so I have no reason to bash or compare.
11-28-15, 03:40 PM
#74
I'm not against the v8 swaps. I once had a 358WHP Monster miata. Small, light, and went really well. After the Miata i bought a 1987 Porsche 944T. I did some mods and got a very reliable 326 wheel hp at 17 psi. Porsche was a far superior car. My question to the FC v8 swap guys - Why aren't you guys swapping in the LS motors into the 944t's? (I know people have) Just curious. They have (over the rx7):
Better braking
better weight distribution (transaxle in rear)
can fit wider tires
better road feeling/cornering
Look very similar
I currently own an 88 Turbo 10AE rx7. Love the car but if I were to do the V8 swap it would be the 944T. Sorry if the pics are flipped.
Any thoughts?
Better braking
better weight distribution (transaxle in rear)
can fit wider tires
better road feeling/cornering
Look very similar
I currently own an 88 Turbo 10AE rx7. Love the car but if I were to do the V8 swap it would be the 944T. Sorry if the pics are flipped.
Any thoughts?
most likely because rolling shells don't fall out of trees like the FCs do, and the parts are much more expensive and less abundant. most 944 turbo cars go for over $10k and you won't often see one that is near the scrap yard with a toasted motor like an FC. more like $5k+ even with a blown motor, which is more comparable to buying an FD project.
better off just buying something already done.
http://spacecoast.craigslist.org/cto/5308602655.html
Last edited by RotaryEvolution; 11-28-15 at 03:49 PM.
11-28-15, 08:04 PM
#75
I'm not against the v8 swaps. I once had a 358WHP Monster miata. Small, light, and went really well. After the Miata i bought a 1987 Porsche 944T. I did some mods and got a very reliable 326 wheel hp at 17 psi. Porsche was a far superior car. My question to the FC v8 swap guys - Why aren't you guys swapping in the LS motors into the 944t's? (I know people have) Just curious. They have (over the rx7):
Better braking
better weight distribution (transaxle in rear)
can fit wider tires
better road feeling/cornering
Look very similar
I currently own an 88 Turbo 10AE rx7. Love the car but if I were to do the V8 swap it would be the 944T. Sorry if the pics are flipped.
Any thoughts?
Better braking
better weight distribution (transaxle in rear)
can fit wider tires
better road feeling/cornering
Look very similar
I currently own an 88 Turbo 10AE rx7. Love the car but if I were to do the V8 swap it would be the 944T. Sorry if the pics are flipped.
Any thoughts?
I just looked and the Renegade 944 swap kit starts at $2100, but that is without headers, cooling system. $2100 just gets the engine in the car. Although that may be compelling if you don't have to buy a T56 trans.
I know v8 headers in the 944 are a problem, Renegade offers mid length headers that will work. You can make BBK mustang headers work on the FC. I do not know the torque tube/transaxle conversion situation. It appears the custom Renegade clutch disk let's you use the stock transaxle. I think with the FC you can mitigate most of the shortcomings to the 944 chassis.
Fender flares are available cheaply to put any size tire you want on the car.
I'd argue the FC turbo brakes are pretty good, but you can easily upgrade them.
Not a whole lot you can do about the transaxle and weight distribution, but the 944 weight distribution looks to be to be pretty close to the FC, so maybe that is not even an issue? From Wikipedia it looks like the 944 weight distribution is 50.5/49.5.
This kinda makes sense as the 944 had a somewhat usable back seat. My dad had one when I was a kid. The FC back seat was a joke. I bet the FC engine was set back further relative to the 944 at the expense of cabin space. That would allow Mazda to use the transmission architecture they already had available.
Last edited by LargeOrangeFont; 11-28-15 at 08:26 PM.