So my motor is gone - convince me to stay rotary
 

Ok so I bought the car in October of 06, the previous owner tells me that the motor was rebuilt 5000 miles ago ( I know I know) and I built the hell out of the car, rebuilt the sequential setup (it was non-seq), put new turbos, fuel system, PFC tuned by Steve Kan, etc etc.

I had it tuned in February and so begins the racing season in the midsouth. It survived the season, for the most part, and did pretty well for me. On the first day of a 2 day autocross event, the last of the season, I chipped an apex seal. The car still ran great at the top end but idled like crap and had no low end power, not like it had much to begin with. Did the compression test and the front rotor has a chipped apex seal, the turbos were unaffected as they still show the same boost pattern at the same rpm and don't have any problems.

The point of this thread is that unless someone can convince me otherwise, I'm gonna put an LS1 swap in it. I really had my heart set on a ported motor from Gotham but now I'm wondering if even that would hold up to the racing that I put that car through. I've got about 8 - 9k in aftermarket parts under the hood so the swap would be an excercise in breakeven accounting after I sell my rotary stuff. The ported motor with all the options would be 4k. In order to stay rotary, I would have to fork over 4k plus have a motor that nobody can guarantee will get me through any more than 2 seasons (I drag race, road race and autocross).

Just contemplating it I feel like I'm ripping the soul out of my car but it just makes economic sense in the long run to put the ls-1 in it. In the short run I'll have more power with the rotary but in the long run I'll probably make more power more reliably with the v8.

I'm asking you to convince me to keep a 13B in the car.

Here come the flames... I'll go put on my Nomex right now!

Thanks in advance,
Jeremy

I've read about plenty of 7's on here that do what you do for racing events and are still going strong. I can't say that I take mine out every weekend, but about once a month it sees some type of auto cross / track action. I've been doing that for about two years now and no major problems thus far.

The problem could be in the tuning. In my experience 9 out of 10 times when you break a seal it will damage the turbine wheel as it exits the motor. The turbos may boost the same but will be out of balance and eventually fail. Take off the turbine housings and inspect them. I guess what it comes down to is what you want. There is no question an LS1 will be more reliable but to some it changes the entire car. If you stay rotary let me know. I'll give you a good price on a ported motor.

Steve Kan tuned it. Hard to argue with his reputation.

No one can convince you to do anything. This is an rx7 forum so there is no question people will say stay with the rotary.

We dont know what you finances look like, nor your patience, nor anything else.

It would probably be better in the long run to go LS1. It will run deeper in the pocket but its a one time deal, sorta like buying something outright. It may seem alot of money because it all goes one shot but having a rotary is like paying interest. It seems cheap at first (especially if you can build your own engine or know someone who can) but as the years go by, it adds up when you coulda went LS1 and it woulda been cheaper.

What im saying is do what YOU want to do, dont make anyone here convince you to do anything. Its your car, do what you feel is right.

Sorry to say but any LS 1 can break and the parts are not free,plus some special fixtures are needed to rebuild one if done correctly .

i know a local guy around here he has a pettit motor and swears by it. he autocrosses and says that his motor is just as good as when he first got it. i dont know exactaly but hes had it for quite some time

keep it real, keep it reliable, keep it rotary ;)

Why pay 4k for a motor that by your own admission will likely break in another couple years? I can build one for 1.5-2k that will hold up just as well. Perhaps that will sway your decision; if not I will take your rotary core if you sell it cheap. :D

Your 50/50 weight distribution will be gone if you implant the LS1, it wont be a great track car IMO. An engine rebuild is pretty straight forward while the LS1 will be plagued with headaches.

Get a proper combination and tuner and you should have no issues. I would say that 90% of rotary engine failures are due to bad or no tuning in accordance with the setup.

I don't agree with the weight distribution making much of a difference. I've driven several of them and it feels like the same car handling wise, except that you have torque and different power delivery. If you're a professional driver, maybe... but it won't make a difference to the average or even above average person. Do you know Roy Johnson II? Hes from Memphis. Used to have a fast white fd that I put together.

nothing is rotary....but rotary....take that away from the car and you lose the mystique...the efficiency....the experiment known as the RX-7.....

go with the ls1. i have yet ....since '98 when i started messing with rx-7's, to hear of one person who has done the v8 swap, and regreted it. if you are even thinking of it, that meens you arent devoted to the rotary.

i loved the rotary and feel of boost until it let go after 1000 miles. i will admit, that it was my neglect that caused it, but it still happened easily.

...as far as the weight distribution, mine is 51/49 (i put it on scales) with a cast block lt-1. i did move the battery and get ride of the abs and p/s, but i also have a/c.

btw, the ls1 is soooo much easier to work on as far as space.

i would love to have another turbo car, but i would leave it stock. good luck with your decision. check out www.v8rx7forum.com if you have questions.

I think the key here is that you said your motor was rebuilt 5,000 miles ago based on the previous owner statement. I'm not sure what history the motor you have has, but it could have very well been built with shit, or just wasn't exactly 5,000 miles on the clock. You may be basing your judgement about the rotaries based on this one experience, which so many factors could have come into play, resulting in the loss of the motor. Is this your first rotary motor?

I think you need a good built motor. Limit your modifications depending on what you need the car for. If you modify the hell out of the motor and drive it hard eventually its going to break, because your opening it up to more vulnerabilities. You could buy 3-4 rotary motors for the price of an ls1 swap, and if your good like me can swap the motor out less than a day. Rotaries are the greatest motor ever!

well, I am on my second motor since I bought the car in sept of 06 (bought it with a motor that blew in 3 weeks) and I can say that I have NO desire to go LS1 even if this one goes. As stated about, that is what makes an RX-7 what it is. Personal opinion, but I think the rotary is awesome.

Trev

I like the opinions I'm getting here. It's true, I don't exactly know if the motor was rebuilt 5000 miles ago, I called Kilo Racing in Florida who supposedly did the rebuild and they said the car sounded familiar but they didn't keep records. It could have been rebuilt with shitty parts.

I love the rotary but I don't think it's the best motor in the world... it's not. It's got a lot of problems and it's very delicate. I don't think the tuning was the issue, if anything I think it was a bad OMP. Currently I've got just about everything under the hood that you can think of short of a single turbo. I've got the capacity to run a huge single turbo if I want but for now I've kept it sequential because I am a purist. I love the boost and the way the motor feels, but it has no low end whatsoever even with the sequential turbos.

I just don't know if I can trust a built motor to make 400 hp and over reliably. I want to know of anyone who has done that and raced their car as hard as I do. I'm out every single weekend, drag racing, road racing and autocrossing the car. That alone takes up a lot of money.

Speaking of money, if I sell all my rotary parts that I've got, I'll have enough money to pay for the swap, so that's an advantage for the ls1 swap. On the otherhand, to meet my goals with a rotary, I have to keep what I've got and spend at least another $4000 to get another rotary motor that nobody can guarantee for more than a year.

Like I said, I'm a purist and I feel bad about even thinking about the swap but then again, I like to concentrate on my driving ability and not so much on my broken car. I hate that the motor is giving up and I wish it wouldn't but the fact remains that it is and I've got to do something about it by February.

Keep up the talk though, you're helping me figure it out.

My rotary is still going and pretty decently.. but im going to swap before it dies. I want to give the engine to someone while its in good condition and not blown (housing and everything most likely still good)

since so many people are against the swaps, i may as well let them buy the "soul".



Im going LS1 and never looking back. However one day I will mod out a rotary RX7 to have side by side with the LS1 ..or i might get an exige... but who knows :P

The V8 conversion is not for the average wrench. Your 8k worth of mods may not fetch 8k so plan accordingly. Plus, a V8 conversion has lots of little costs that add up, much better off buying one that is well done rather than do your own and live through the testing phase.

If you do go V8 start thinking about PS, A/C, motor hp, differential gear and/or upgrade, and how you are going to get small custom stuff fabbed as well as getting the unibody welded up in places.

Cheaper to stay rotary and run race gas on weekends. Do the V8 if you really want a V8.

Actually I was estimating that my 13k worth of mods would fetch 8k. I do appreciate your input though.

I've been thinking about the PS and the A/C. I've got a friend who did the conversion a while ago and he's walking me through the process. He doesn't have A/C though and I want A/C so it's something I'm gonna have to figure out on my own. I've read a bunch about the wiring but it's the hardlines that I'm more concerned with. The welding is no big deal, I've got people that can help me with that. We've got a good little community of gear heads around here with the famous dragstrip and SCCA stuff going on, I've got friends with varied backgrounds. I wouldn't attempt the swap if I didn't know people that have already done it.

As far as HP, I'm making 331 to the ground and I'm hoping an LS2 motor would be right about there so I wouldn't lose any power. There's also the whole I'm putting a cam and tb on it thing. Should be strong enough to accomplish what I'm looking for. The diff is already about to go so I was already planning on upgrading it.

I am sorry but the no low end and track use don't add up. When I track my car its never under 4K where the power starts. So whats the deal w/ low end you plan on pulling your boat w/ the 7??

As far as motors I have seen a bunch of rebuilds w/ excessive endplay. When you are building a motor to see high rpms this is very critical and overlooked in alot of builds wether backyard or reman. Its the details that count.

If you want a LS1 sell the 7 and buy a vette. Just my .02.

Oh and ditch the twins they are worthless IMO. Unless you like to complicate things and hunt down boost issues.

No boost issues, I am full sequential and I did the vacuum hose simplification myself and know the system backwards and forwards. I see boost at 2k and put down 331 to the wheels.

About your no low end comment, I also autocross the car so that is an issue.

I have 10lbs of boost by 2300 rpms and 16lbs by 3K 60-1 .84 hotside. I actually have problems keeping the car out of boost on the highway. All on the shorty HKS manifold. Thats why I said ditch the twins. They are too hot for racing and autocross IMO.

It all comes down to you personal preference. The rotary engine can be very reliable if built well, tuned well, and maintained well. You can control the maintenance and tuning, but you can't look over the shoulder of your engine builder every step of the way (unless you do it yourself).

You might want to look up info about "Damian," I know he does some serious racing on the 13B.

In the end it's what gives you confidence in your car, you don't want to worry about breaking your motor every time you take it out of the garage.