What to know about V8 rx7's? - RX7Club.com - Mazda RX7 Forum

What to know about V8 rx7's?

Old 11-16-16, 11:58 PM
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What to know about V8 rx7's?

what should I know about building/swapping an Ls into a RX7? I sold my stock 93 rx7 a few years ago and regret it, so now I'm wanting to find another one and swap an LS into it. But before I do what's everything I need to take into consideration when building it? The stock motor and trans will be coming out for sure but I have never done anything like this before so not sure where to start other than knowing what motor I want. I plan on going with an Ls3 Erod crate motor from GM. That way I don't have to take a trip to the state ref.
Anyone want to chime in and give me some pros and cons before I embark on this journey?
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Old 11-17-16, 09:07 AM
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I can think of alot more pro's that I can think of con's on this kind of project. Honestly every one I've seen is a ton of fun!

If you need any assistance with the swap we offer a complete swap package for these to simplify the process.

Mazda RX7 FD LSx Swap Kits - Sikky Manufacturing
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Old 11-17-16, 09:54 AM
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That was going to be my next question. Do I just use any mounting kit for any of the ls motors? I plan on using an LS3. And how do the kits differ from each other? Are some stronger or different positioning or how does that go?
I would like to have most of this figured out before I start the project just so I have all the parts needed from start to finish so the car isn't down for too long.
is any fabrication needed when doing this kind of swap?
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Old 11-17-16, 10:15 AM
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So all of the motors in the LS family share engine mounting locations so you are free to switch between them as far as the mounting situation goes.

The two kits we offer just vary in completeness, one comes with a harness and the other does not. As far as strength goes our mounts are as durable as a mount can be, they are machined out of a solid block of 6061 Aluminum.

Our kit we offer minimizes the fabrication needed on this kind of swap. However some small things will need to be done (exhaust, coolant hoses, etc...).
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Old 11-17-16, 11:16 AM
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So some thoughts/advice I would have for someone about to do the swap:

1. Put a big cam in the car. The blop blop blop sounds so good and when you hear other people with cams you will want one, so may as well do it from the start to not have to take the whole thing apart again.

2. Transmission. For the ease of not doing work over I would go ahead and do a built up T56 or a T56 Magnum from the start. I ran a stock T56 and we ended up doing double the work when it blew and we upgraded to a T56 Magnum, would have saved a lot of labor/time to just do it from the beginning.

That's all I can think of at this second but I'll pop back in if something comes to mind. They are super fun cars with the swap and you will absolutely love driving it around.
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Old 11-17-16, 12:13 PM
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Oh ok cool. So as far as the mounting goes there is no need for any kind of fabrication mounting the motor? It's straight forward just bolt up the brackets and bolt up the motor correct??



yeah I was planning on canning and having the tranny built up, I don't want to do things a second time lol
do you know if you can keep ac, heater, power steering etc when having an LS rx7? Is there space for it? Where I live we get cold for like 3 months and that's about it lol the rest of the time it's warm so I want to make sure running an AC would be possible.
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Old 11-17-16, 12:37 PM
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Yes, depending on what parts you are using, some kits can be better imo. I have parts from Hinson, Samberg, and Sikky; the sikky kit is the newest and the parts are very well made, I have the shifter on my T56 Magnum. I have some Hinson swap parts, as my car is an older swap, as well as a Samberg rear subframe and rear diff mount as they seemed like an easier choice for my rear end setup.

I'm in Texas so A/C is necessary, lol. You have plenty of room (a ton more if you are removing the abs), my car has everything working except the cruise control.
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Old 11-17-16, 01:02 PM
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Oh ok cool. So as far as the mounting goes there is no need for any kind of fabrication mounting the motor? It's straight forward just bolt up the brackets and bolt up the motor correct??


There are two ways of doing it that I am aware of.

Aftermarket subframe and relocated steering rack with bumpsteer correction - the old standard.

And then to comply with Formula D or something (need stock subframe on swaps),

20 years later Sikky found you could just make a custom oil pan and keep the stock FD subframe complete with steering rack location.
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Old 11-17-16, 02:58 PM
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So it sounds like sikky is the way to go if it takes the complication away. So now that I know which mounting kit to go with here's the next question. The rear end....is assuming the stock rear end will have to come out, so what rear end should I go with? My overall plan is to daily the car and occasionally road course it.
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Old 11-17-16, 03:43 PM
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Just a heads up while were on the top we are having a black Friday sale next week. So if your in the market it's a good way to save!
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Old 11-17-16, 04:59 PM
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Oh sweet! I don't have the car just yet! But I'm hoping by next week to have it so this way I can get that deal. I don't think I'd need the wiring harness, so what deal would I get next week for the mounting kit without the harness?
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Old 11-18-16, 07:44 AM
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The stage one kit is what you would need.
Mazda RX7 LSx Mount Kit - Sikky

Reg price - 1799.99
Black Friday - 1529.99

Also free shipping
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Old 11-18-16, 04:51 PM
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The car will feel a little different after the swap. No question for anything straight line, the motor can be a monster.
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Old 11-18-16, 06:04 PM
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Originally Posted by Supernaut View Post
The car will feel a little different after the swap. No question for anything straight line, the motor can be a monster.
Yeah I'm sure it'll feel a bit heavier but I'm sure the power will more than make up for it. I want to set this car up for a road coarse more than straight lines so we'll see how this project turns out.
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Old 11-19-16, 12:57 AM
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Originally Posted by SP_Rocket View Post
Yeah I'm sure it'll feel a bit heavier but I'm sure the power will more than make up for it. I want to set this car up for a road coarse more than straight lines so we'll see how this project turns out.
In terms of lap times, I'm sure the power and ease of drivability will help but for me, in terms of fun, that heavier feeling took just enough out of what I loved about the car. Even though the change was slight and handling was still awesome, it was enough for me to strongly prefer my rotary FD. I'm not bagging on v8 FDs, it's just for me, and more importantly, maybe you, might not like the car as much as you think you would after the transformation. I hope you have a friend that has a swapped car that will let you drive it. It would be wise to try it first.
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Old 11-19-16, 03:27 PM
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Originally Posted by Supernaut View Post
In terms of lap times, I'm sure the power and ease of drivability will help but for me, in terms of fun, that heavier feeling took just enough out of what I loved about the car. Even though the change was slight and handling was still awesome, it was enough for me to strongly prefer my rotary FD. I'm not bagging on v8 FDs, it's just for me, and more importantly, maybe you, might not like the car as much as you think you would after the transformation. I hope you have a friend that has a swapped car that will let you drive it. It would be wise to try it first.
i completely hear you and understand you. And I've yet to meet someone that has an LS rx7, I would love to drive one. But the main reason for wanting an LS in the rx7 is drivability, ease of a v8, fuel efficiency and no turbo needed for power. This car would be my daily driver and sometimes for long distances. My 93 rotary rx7 I use to have was great, I loved it but it was horrible on gas and I couldn't make any kind of power without having to "hot smog" it. I'd like to be able to make this rx7 smog legal with the LS motor. But yes you are right I loved the handling on the stock rx7 and I do need to find someone that would let me drive their v8 rx7 before advancing on this project.
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Old 11-20-16, 09:22 AM
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If you put a cam in an Erod, it is no longer smog legal.. so try that at your own peril.

In an FD it is actually very easy to keep the 50/50 weight balance when performing an LS swap so it won't handle much different at all. Additionally the swap is about weight neutral. By the time you are done the car weighs about the same. This is very well documented in many FD swaps.

Also look at the Ronin/Samberg engine swap kit. That has been the standard for many years.
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Old 11-20-16, 10:47 AM
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Originally Posted by LargeOrangeFont View Post
If you put a cam in an Erod, it is no longer smog legal.. so try that at your own peril.

In an FD it is actually very easy to keep the 50/50 weight balance when performing an LS swap so it won't handle much different at all. Additionally the swap is about weight neutral. By the time you are done the car weighs about the same. This is very well documented in many FD swaps.

Also look at the Ronin/Samberg engine swap kit. That has been the standard for many years.
yeah I keep reading about these kits, I'm not so worried on the swap it's the fabrication that has me worried, I want to try and have almost everything bolt on. I know the exhaust will have to be fabricated, but as far as dropping in the motor and tranny I'd like it to mate up well without welds etc.
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Old 11-20-16, 11:02 AM
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There is little fab needed with either mount kit. There is some cutting and clearancing needed, but not welding and fabrication.
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Old 11-20-16, 04:27 PM
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My original FD with LS1/T56 and factory rear 3:90 diff running, 13" brakes, 18x10.5 CCW's 285/30/18's all around was 2800lbs with 50/50 weight distribution and full tank of fuel Touring edition (sunroof). Heavy dual 3" exhaust, all stock glass/body panels, no a/c. The car pulled 1.13g's on the skidpad in 2005 for the Sport Compact Car Mag USCC so anyone that says the cars handling is upset..... doesn't own a properly sorted swap.
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Old 11-22-16, 01:35 PM
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Originally Posted by gnx7 View Post
My original FD with LS1/T56 and factory rear 3:90 diff running, 13" brakes, 18x10.5 CCW's 285/30/18's all around was 2800lbs with 50/50 weight distribution and full tank of fuel Touring edition (sunroof). Heavy dual 3" exhaust, all stock glass/body panels, no a/c. The car pulled 1.13g's on the skidpad in 2005 for the Sport Compact Car Mag USCC so anyone that says the cars handling is upset..... doesn't own a properly sorted swap.

i still have that issue of scc ... the build inspiration behind my car from day 1
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Old 01-23-17, 08:09 PM
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I too am on the path for a V8 swap. I'm torn right now, and just about ready to pull the trigger on the swap kit. I am looking to learn a bit more about the Sikky kit before I commit. Plus, would love to jump in on a deal if they have one again soon!
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Old 11-30-17, 12:45 PM
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The only thing I can tell you is to tally up the total $ for all the parts and labor you think you'll need to get it done, then multiply that by 2x or 3x and then BOOM you've got yourself the actual cost for a completed V8 rx7. Aside from that enjoy the journey!
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Old 12-16-17, 07:58 PM
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Originally Posted by erotomania View Post
The only thing I can tell you is to tally up the total $ for all the parts and labor you think you'll need to get it done, then multiply that by 2x or 3x and then BOOM you've got yourself the actual cost for a completed V8 rx7. Aside from that enjoy the journey!
True statement. Every swap I've done has gone over budget. My rx8 swap was the only one that was close to the number.
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Old 04-25-18, 06:25 PM
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Incredibly useful thread to someone planning on slapping an ls3 into an FD! Thank you.
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