Hello everyone My name is Marcus Kener and my friends
call me Kenny.

I do realize that a 20b swap is a huge undertaking more so than I can imagine and I have gotten a couple
expectations from threads on here such as ThmMotorsport build and other sites.
The conversion will be done mostly between closely knit friends and a professional will be brought where the services is needed.
There are also experienced people who will chip in little nuggets of information
when necessary.
We want to do most of it ourselves so that we can know every nut and bolt

We have already considered the 13b and realized that its not in our interest to go that route in the long run.
This project should be off the ground and making progress in around 2-4 years and during that time research will be priority but one thing that is puzzling everyone is which platform to place the engine in.

Currently I have $20,000 in savings and $6000 that friends are putting to get it off the ground.
We do hope to raise the budget in the future and can put atleast 10k towards the project every year if the saving plan goes well.


One thing that puzzles us to no end is the platform to put the swap in
So far we have considered the Rx8 , Rx3 , Bmw e36 , Bmw M3 gtr and old 911 chasis we have seen some good prices going around for the above shells except the rx8 .
Once we settle one a choice for shell priority will be getting the chassis tubed and working on the swap (engine management , wiring etc) and of course suspension will right up there on the list.

One benfit we are looking at with the rx 8 is using the engine in it for the time being and rack up some seat time but that's not a deal breaker for us.
I think I speak for the group when I say that we are not looking to build a monster right off the bat but a reliable machine and one that is sorted thenwe can move towards that direction.


The car will be competing in circuits and sprint with 4 laps minimum and
the tracks will be generally fast but our home tracks are not very fast so the ability to provide cooling to the engine and breaks is very important.



we are open to any suggestions for research and any advice.




OPTIONAL READING


This project was inspired by our love for racing and wanting to give the love to the rotatory that a lot of piston riders put down.

Sure we could slap a vette engine in and call it day and have tons more money to work on other aspects of the car but we all decided that this is the path we want to go.
We all have a fair amount of Super karting background but we all shared the desire to take it even further.


We will also have a b18c1 build to compete in some road races and for the school I will be enrolling in next month.

 

Good luck with the build it sounds like fun.

 

Well, when I saw your thread title and post count, I groaned "not another one poster noob asking about a 20b swap!!?!?!?!1111" But then I read, and it does seem you are a couple steps ahead of where most people are that come on here asking the questions

Considering you are going to start with a shell and replace the entire suspension, there really isn't as much of a reason to go with an RX-8 as you may think. Honestly, the best advice is to pick the lightest shell. The RX-8, when stock, is an absolute brilliant chassis. However, it's just a starting point. You can take any decently balanced car out there and make it handle just as good as the 8. It's only brilliant stock to stock. Once you start with an empty shell that allows you to put the engine where you want it, every appealing point about a stock RX-8 becomes largely moot, OR is easily replicated in just about any other chassis by choosing the correct suspension and putting the engine in an advantageous position.


Side note and advice:
Giving out your name, and all of those contact points I see in the little icon on the left seems "cool" until you realize that spam bots and ill-meaning information seeking bots will use that against you. Minimize your personal information on the web, not maximize.

 

where are you located? half of the battle is knowing the available resources around you.

if i had known what i know now 4 years ago, i would've spent 1/3 as much and got this running much sooner.

 

@wrightcomputing

Thank you we will definately need tons of it



@RIWWP

I made sure to do a fair amount of lurking before asking any questions
Wow I never though of if that way initially this was going to be a street car but then I thought why waste so much potential for street purposes and I decided that to take full advantage of the power the best thing to do is let it go wild on the track.

Just finding it hard to decide on which shell to go with.
At this moment I am talking to my friend and we are tossing ideas back on forth on what is the most ideal solution.
If I had to narrow it down the choices would be the BMW e36/46 personally but I am trying to look at it from all angles.

Thanks for the tip about the personal info but none of my account info was in the Facebook or email area i just had "none" there.



@stickmantijuana


I am 1,640 miles outside the states and thats the best info I can give right now.
This project is sort of a secret and I know that people in my area view this forum regularly .
We do have rotary shops in our country and more than sufficient machine shops to take care of the fabrication ,welding etc.


Also looking at putting together a part list so I can begin some reading up on that also.

Again feel free to provide any info you have

 

Anyone else care to chip in?

 

I'm sure you've seen this, but this is a good build thread from rx7club.com that is somewhat similar to what you're talking about doing.

http://www.rx7club.com/showthread.php?t=937570

I agree with riwwp in that your chasis choices are all well balanced cars (minus the 911 for the most part) so chose the lightest platform and go from there. The overall chasis of the RX-8 is very stiff and quite light when stripped down though. Already starting with double wishbone front will give you more tire width options than an e36/e46 with a mcpherson strut set up. They tend to have narrow wheel wells and inner rim clearance at the front strut. I know you'll be redoing a lot of the suspension and fender flares are always an option, but it's something to think about.

Good luck with whatever you end up with, and be sure to post a link to your build thread here regardless of chasis choice. I'm sure i'm not the only one that would follow it.

 

I still need to finish reading that thread its like I start reading then I just start looking at the pictures.

So the double wishbone on the rx8 vs the macpherson stut on the bmw m3
could be deal beaker on tight tracks?
I will have to go read more in depth on the two setups but a general idea would be good also.
The wheel width choices will be affected also?

The chasis on the rx8 is stiff you say?
IS that good for tight tracks?



I am going to read up on the chassis on the suspension setups and come back with some more concrete questions

but feel free to add anything

 

If you are starting with a shell, the stiffness is all in what rollcage you put in.

In theory, you could also put in whatever type of suspension you wanted. For example a BMW shell and the suspension items/geometry of the RX-8. Requires fabbing and making sure your mounting points are really solid structurally, but given the scope of your project, not impossible either.

It's why shell weight is really the only big deciding factor. After that it's all in what you want to delve into vs what you would prefer to avoid.



Have you considered a "shell" that isn't a road car at all? I mean, road cars were designed for road regulations and certifications. Ever consider like a Factory5 Roadster shell? Or a Caterham type? Etc... Lots of kit cars for racers out there that are even lighter than any road car shell, and remove plenty of annoyances that a road shell could cause (clearance issues, etc...)

 

There are pro's and cons to both setups. Both are very capable when done right. BMW and Porsche have been running Mcpherson setups for years and years. I would say that they are doing it right. I wouldn't read much into that thread in your quote though as it pertains to a whole different style/class of car. FWD makes a huge difference in how a front suspension performs.

Just to expand on what i was saying. With a mcpherson strut type front end, you tend to have less inner wheel clearance due the shock body and spring being closer to the hub. They do tend to allow for greater steering angle depending on suspension design.

Double wishbone when done right has plenty of steering angle, even for the tightest tracks and generally allows for more inner wheel clearance due to the shock and spring being further in board.

The rx8 for example has no problems with angle even on tight autox courses. Drifters are about the only people that want more. We can also fit 295's all the way around with the right wheel specs without much effort. The most i've seen an e36 M3 fit without flares was a 245 with both the front a rear fenders rolled. Anything further inward hit the exhaust on one side in the rear, and the spings/strut in the front.

I'm not expert at all, but it's something to think about since you're going for a dedicated track car that will have a high speed potential.

 

This is an excellent point/suggestion. While the kit will be more than a bare shell, it will be require less fab work in the long run. The Ultima GTR comes to mind if you don't want an open cockpit and open finders.

 

Ultima GTR kit:


I'm sure you could spec to order.

 

yep. You can pretty much order as much or as little as you want.

 

Very Very interesting

I wont be the only one using this account to post( is that allowed?)

Thanks guys for the opinions and I would have to talk to my team about the possibility of going in that direction and again the rules might prevent us from going that route.

In all honesty I dont think they will like the idea of buying something pre built by someone else but who knows.
They would probably lean more to either building from the chassis up or heavily modding a chassis to work with.

I did read the info you guys posted I just will have to build on to what you guys posted through further reading to satisfy myself.


keeping your guys ideas in mind , would you say designing/ modifying around the chassis of the M3 e36/e45 series or rx8 would be good route to go down?

I think building the chassis from scratch with the M3 or rx7/8 design in mind will be a good or bad idea?



In 30 mins I am going down the pub to present the new info I have and also will direct them to this thread.

BTW if your wondering its just 3 of us

 

It's expensive to build a race car from a street car no matter what. The m3 chasis is very proven as is the rx8 chasis. Go with whichever you are more comfortable with. You'll probably have more options with an M chasis as far as suspension components go. There's a lot of race ready aftermarket support for them.

 

How much whp are you aimming for?
Just keep in mind about the grip and wheel clearance.
Personally I would pick FD or SE chassis, simple it's been done so many times, way more resource out there if you guys run into any issue. Unless u guys like adventures, which also means more money due to trial and errors.

What transmission are u gonna use and who's tunning the ECU?

Good luck with everything, keep us posted.
Cheers~

 

So to take a guess, would you be in Jamaica?

 

Back from the PUB

Well after heated tempers and some Cold beers no decision was made

Mine BMW E36

Keith Rx7 FD

Domario: Rx7 FD


The idea about buying any sort of racing kit was shot down and I agreed with every point they made.

They both ended up teaming up against me on the subject and I tried to make the point of being adventurous(expensive) and doing something different.

I mean come on Rx**= rotary is already what comes to everyone's mind and doing something different like Rotary powered BMW should get some attention from sponsors.

Even though buying the chasis/shell to work with is left to me I like to hear everyone's opinions about it.

Keith and Domario did not oppose to the idea of the M3 E36 but preferred working with the Rx7 but I still hold my ground on choosing the M3 E36 chassis.


I understand and thats why I am leaning towards the M series chassis.
Keith and Domario rather working with the RX7 than the Rx8.



well thats why we are so conflicted over the choice for the chassis.
We dont know which one to go with M series or RX7 FD

I dont mind adventures because I like to be different and at the benefit that it might attract potential sponsors.


We are aiming for 400-650 reliable WHP and for the transmission its undecided Keith is researching that.



Good guess but no we are not building for the Caribbean.

 

I guess the decision Comes down to the Rx7 FD chassis vs the BMW M3 E36 chassis

my vote goes to the M3 chassis and they rather the Rx7 not the Rx8 Chassis.
The decision is up to me but I am leaning towards the M3 and will mostly likely go with that.


Now some reading is in order for suspension , ECU, Rotary , Chassis setups etc... b
oy this is going to be lots of reading.

Will be back when I have done some good amountreading.



l

 

I do not have a good overview over whats written about this, but i have two friends who run RX7 housing and RX8 internals, rotors and eccentric shaft. This because of lower weight of RX8 parts.

They get around 300 flywheel hp on two rotors.

 

You need to speak with Speedsource-----why not use them--great people to work with.
IDK but to me there is just something wrong with the 20b sound coming out of a bmw chassis.....?

 

non-RX8 specific attention whoring threads belong in General Automotive

 

Well we went to one of the less recognized/compete for fun team today since they are fairly close 3 hrs drive and we got a lot more information than we could have imagined.

We have decided to go with the RX7 FD chassis and the BMW idea was put down but I am still thinking of it.

The BMW 20B conversion is cool yes but Ideal no was the main opinion.



Mario and Keith are having a heated debate with me of going 4 rotor (26B)
Which is possible but thats pushing it to the limits and will set the project back at least 2 years from even getting up and running.
I try to tell them that parts for that thing is expensive and and even if we do go that route is going to cost money and we dont know how reliable it is to last 7 hot laps compared to the 20B.

I laid out the potential costs and they still arent convinced that its better to consider that later(way way way later) and I only hope that they get this idea out of their heads and soon.


Well I can blame(not seriously) that guy at TermSport for telling Keith that if we got BMW route is better just go all out and work on a 26B but then again I had the idea of going 4 rotor I just did not think out loud.

When I looked into what would be necessary for such a build.....you can imagine.

So basically the main opinions was RX7 20B and BMW 26B although I dont see why we couldn't go with 20B conversion in the M3




Well I am off to do my reading on some stuff and pick up the slack of the others.

 

If it helps at all, the track ready 4-rotor put together for time attack cost ~$100k+ when it was all said and done.

 

Well when I looked it up it was 40K bare minimum but that was info from 2 years ago and for a circuit setup.
I would think a time attack setup would be more stressing to the engine than a circuit type thing but then I may spouting crap.
I did not bookmark the site but its somewhere in my history among other things Lol


The next update that we should have is a pic with the candidate chassis among other things.
I am going to talk to to keith tomorrow about us taking a drive over to a chassis shop and get some experienced opinions.