700hp 13b internals
 

Hey im a new to the Rx7 world and i'm looking to build a 700hp RX7 to use on the track and street once a week or so. Im wondering what kind of upgrades to the internals I should look for? Ive been a muscle car guy all my life so the information i heard on RX7s wasn't exactly the most accurate. (When I say internals i'm referring to the rotors, crankshaft, and housing). I hear that if you get a low millage block on the 13b and get an aftermarket crankshaft 550-700hp is an attainable goal. And one last question. So this guy ive been hanging around has the coolest LS swaped RX7 that he uses 2 tunes on. One runs the motor using 7psi for the street and the other at 15psi for racing. Is he just yanking my chain or is this possible? If so how could I replicate this on my build?

There really are no upgrades, you use the stuff Mazda built. There are not really any aftermarket parts anyway. Guru used to make a three bearing eccentric shaft, but this was more for naturally aspirated engines spinning at super high RPM, like 12k+(And I understand that they are really more trouble than they are worth)

Thanks man! so your saying that stock internals will let me reach my goal? And im afraid im not looking for RPMS higher then 9.5K :) if theres one thing ive learned from nitrous RPMs without a large budget blow motors

Well you are going to need to port it to reach those goals.

But most of the work will come from the supporting parts - turbo, intercooler, ignition, fuel system etc etc

Lots of good information here, especially if you look through some of the high horsepower build threads.

Get to 400whp reliably first, learn to drive that before you try for more.

The cost to make and maintain hp goes up exponentially above that.

You figured everything else and you are down to the amount of boost on the street vs the track...
dont you just love when the 10year olds get ahold of a pc.. !!!

Reread it... a friend of his has an LS swapped car that has two tunes in it. I've never experienced 15psi in an LS-anything, but I can tell you that 11psi in a 413ci LS2-based engine is pretty stupid for power :)

This is very doable with many ECUs. I know Megasquirt can do it. I have also done a few FAST XFI installations with a "clicker switch" that can switch between four different tunes. We would usually set them up for anti-theft (null tune, vehicle will not run), valet (will not go over 2500), low boost, and high boost.

Given how the higher level Megasquirts can do map blending based off of ethanol content, it's very easy to make a super low boost tune and a super high boost tune and use a knob on the dash to have infinite adjustability between the two by using a simple potentiometer to vary the "ethanol sensor" input's voltage. Obviously you would not be able to actually DO a multifuel tune with this setup, but jeez the computers are cheap, compomises have to be made...

I thought pretty much everyone with a turbo and programable ecu had at least two boost settings since the day these technologies were available to the public back in 1873?
tune for the higher boost setting and then simply turn the boost down?
15psi LS would be bonkers though haha.
also, 700rwhp two rotor would probably want at least some nice pins and extensive machining to be half reliable.

The statement that there are only really Mazda OEM parts is untrue. There are a number of manufacturers in Australia and New Zealand making billet machined side/centre plates, rotor housings and e-shafts (PAC Performance, ProMaz, PPRE, BilletBoss etc etc). They have been around for years and are used on many of the 7 second and faster cars.

That said, they are not needed at the 700hp level...But as WANKfactor correctly point out, you would want studs/dowels and all the usual internal modifications/machining/clearancing etc at this level.

gia sou re kypreo!!!!!

It's all shit, though. None of it is measurably better for performance or reliability than the stuff Mazda built.

This isn't saying Mazda Uber Alles, it's more of a lament that the aftermarket always sucks. The piston engine aftermarket produces some good stuff, if you have a machine shop at your disposal to finish up what they were too cheap to do before selling product. Rotary wise, there's.... nothing.

^ yeah you will be using mazda components, but dont think you are going to win the lottery on an unopened block with 700hp every time either. It will need more than ports. It will need significant strengthening, balancing and other tweaks. To the op, in other words $$$$$ and even then you will likely be blowing motors or at least rebuilding regularly. Then you have transmission woes. There is no Mazda transmission that will happily take 700hp. 700hp is getting toward the ragged edge for these motors and probably not a great idea as an introduction to the rotary world and a streetcar unless you like building engines a lot. 400hp happy as larry.
700hp LS makes more sense.

at 19, can u even afford such a thing? i think it's more about bragging rights. and have it wrapped around a tree in no time.

Shit howd u know I was 19? And yeah I can afford it im living with my mom to save $$ and I have a full time job as a HVAC repairman. My budget is 10K-15K. Any advice? Is my goal to large for my budget? and ill try to be careful off the track lmao.

Yeah its looking like I might go with the LS swap or settle for 400hp. It probably be a better idea to learn to drift the RX7 at 400hp instead of jumping in at 700hp. Thanks for ur imput tho

Depending on what needs to be replaced and what mods are on the car, you will have more than $15K just getting to 400rwhp. Just the clutch to support 700rwhp is going to run $2500+, if it were easy and cheap to triple the power output, everyone would have 700rwhp. If the car is close to stock don't even bother with the 13B, just get a 20B.

It IS easy and cheap to triple the power output. My 4 port 13B made almost 3x the power of a stock four port 13B, and all I really needed to do was a good intake manifold, a decent flowing exhaust, and a bridge port.

You guys what play with turbos (you mean like trucks have??? How lame) are the ones who have all the problems.

(disclaimer: My winter/backup car has a turbo. It also has 8.5:1 compression, makes 300hp from 2.5l dead-stock, and is computer-wizard everything. It's not an OMG car, more of a "Jeeves, accelerate me thataway with all haste" car. For fun, natural aspiration is best aspiration)

https://cimg4.ibsrv.net/gimg/www.rx7...1c2b80908b.jpg

Glad I get to use this again. Always recycle.

lol

I almost responded when I read the initial post, then I was like F it. He'll probably ask how to adjust the valves next.

Unfortunately your budget is no where near the amount needed for a 700 rwhp build, have you even looked at the price of turbos, intercoolers, radiators, injectors, fuel rails, oil coolers, clutches, transmissions, computers etc etc? Even getting to 400 at that price would be a real challenge, even if you cheap out and do the labor yourself (and assuming you already have a running RX7 with a good engine).

Speaking of which, I have to ask - do you own an RX7 yet? Your budget will be fully used just buying one......

I strongly recommend you do a lot more research. Nice cars, with high power, built well are not cheap. If they were, don't you think a build as expensive as mine would have more than 375 rwhp?

I've got $20k in go-fast parts alone from a fully built semi peripheral port keg to CDI ignition and I'm just now closing in on 700hp. The first 400 is easy, the next 300 is not.

If you want 700hp out of $15k, you're going to need to buy a junk beater roller and then swap an iron block 5.3 in it and spray it with a stupid amount of nitrous. 700hp simply isn't happening on a 13b without serious fundage and ability. And at those power levels, you best have money to replace the expensive keg when it lets go and not mind doing so, because it ultimately will.

-Skeese

700HP on a 2 rotor is NOT realistic or smart. It's flat out STUPID unless you own a rotary build shop (and even they will tell you you're stupid) and want to show off or your drag racing with it or just want to throw away money. it would be useless on the street. It's like building a 2,000 HP v-8
but at least the v-8 will make more than 3 passes before it grenades

It is realistic, and can be smart if you are in the right position. I don't own a rotary shop and am not a drag racer, but can't say I haven't spent a ton of money. The point is not to run 700hp everywhere, but to have a 500hp street FD that you can crank the boost knob on and have 700+ on demand OR run a boost by gear setup so that you dont see the 700 boost until 3rd or 4th so you can hold traction and pull on the big end. I don't know about where you are from but 500hp, even in a FD, isn't enough to keep up with the big boy street cars here in TX.

That all being said, if you build the motor and supporting system to hold 700, then run 500 most all of the time, the engine will likely last alot longer than the guy who builds for 500 then beats on 500 constantly. The key point here is that it is perfectly realistic and doable, but you have to have money to spend and know exactly WTF you are doing, or else its a wash and a time bomb.

Your opinion on the matter doesn't make anyone else stupid for doing something else.

-Skeese