1984rx7

I am thinking of doing a sr20 swap on an FD. I love the rotary engine, but the maitnence on my gsl-se are very very expensive, so I figured that I would do what FALKEN did and put in the sr20. please give any info on doing this, and where I can get the motor mounts.

Stanello

iTrader: (1)

What made you choose an SR20? There are much better options out there IMO

1984rx7

what other than a rotary would you put in ????

Stanello

iTrader: (1)

If I was going to do a piston engine swap

LS1, LT1, 2JZ... those would be my top 3

1984rx7

man but the gas mileage is my problem

andrewb70

I get about 25mpg on the highway in my LS1 powered FC with the T56 trans. 6th gear is .5, so it makes the stock 4.1 gears act like 2.05s.

Andrew

Nihilanthic

Youd be trading DOWN displacement... going from 2.6 to 2.0. That means youd have considerable lag running the same turbo a typical 13B would run.

You might seriously want to consider other options.

travisorus rex

It has been done. Twice I believe.

That means that there is some info out there of how to do this.
Unfortunately, everything will have to be custom made.

1984rx7

there is a falken racing FD driven by yamamoto, that is the only one that i know of. but please give as much critisism as you can. also i have another FD in my club that is getting a 20b with an auto tranny, where can i find a manual tranny for the car????

Hellspawn

I get 26-28mpg freeway here with my LS1, for what it's worth.

travisorus rex

I think that it uses the 3rd gen tranny.

BTW, ever been to Petal, MS?

Eternal_Gamer

iTrader: (10)

No offense but that Sr20 is WACK in a FD. Leave the engine in a Silvia. Dont get me wrong though, Silvias and sr20s are bad azz, but a sr20 has no place in a FD car. You gonna be hella slow for the money your gonna spend. The Sr20 cannot match up to the 13b motors. But if you plan to do that, its up to you. Why not just rebuild your FD though? Thats whats good about a Rx-7, the Rotary engine.

Nihilanthic

Whats good about the car is the CHASSIS. Its been demonstrated REPEATEDLY - its just as good with any other engine as long as it makes enough power. This is a SWAP subforum and a SWAP thread.

Anyway, SR20 has less displacement than a 13b, and the rev potential is about the same. The only gain would be reliability at the cost of spooling up later and having to rev higher to get the same power.

If you want to put in an engine other than the 13b a v8 is kind of a "cant go wrong" sort of plan. Also, consider the Ford 2.3 - ***** VERY cheap for it, its very strong, and it can make tons of power on a turbo.

travisorus rex

And the 13b can' match up to the LSx motors.

fi addict

any thought put into the rb20dett or rb26det?
i know sr20det's have made 450hp w/o issue... that might be the part that attracted you ...ay'?

AXMDR787BOY

I hate to say it, as good as the SR is, but there are indeed better options out there. If you really want to do it anyway, it will be plenty of fun. I used to have a SR modded S13. There isn't anyone offering a bolt-in solution for the SR that I am aware of. Custom mounts and driveshft are what you will need, so find a good welder and someone that can build a custom shaft for you.

There is someone that offers a VG30DETT kit. That is the 300ZX motor. I would keep that in mind if you really want a boosted bolt in solution without lots of fab work. Otherwise there is the good ole' American Iron.

Dude, seriously. Stop. You have no clue what you are talking about. Like I have told you MANY times. The 13B IS 1.3 litres of displacement. AIR FLOW DOES NOT DICTATE DISPLACEMENT. Just because a 13B blows as much air as a 2.6l four, doesn't mean it is 2.6 litres. An engines displacement is merely a measure of each cumbustion chambers peak displacement. A 13B has two cumbustion chambers with a peak of 650cc each. 1300cc Total. NO ifs, ands, or buts about it.

Lets take a 350 small block for example. It has a stock bore of 4in and stroke of 3.48in. That gives us about 43.7CID. Now multiply that times eight and you get 349.6CID or 5735.2cc's. Now if we were to measure a SBC based on it AIR FLOW and VE it would be FAR less than 5.7liters. Now do you get it?

You are right about the turbo, but not simply due to displacement. Rotories typically use a turbo with a much higher A/R than a piston motor because of it's airflow. If they ran lower a lower A/R, there would be no lag, but it would also take the turo WAY out off its efficiency range, and destroying it rather quickly. Bigger motors can't spin a turbo with a high A/R like a rotory can.

You know nothing about the SR20 So how can you make these claims? A 13B can rev much higer than a SR20. The stock powerband on an SR is quite good and power comes on very early. I used to have an SR powered 240sx that I built. We will just chalk this one up to another one of your...

...statements.

Nihilanthic

THE 13B SUCKS IN AIR AT THE SAME RATE AS A 2.6 LITER 4BANGER TURNING AT THE SAME RPMS!


You just dont seem to realize that everyone but mazda goes by *TWO* revolutions. .65 x2 x2 = 2.6.

Also....
Uh. If we measured a 13b the same way you measure a 350, it would be .65 * 6 for all 3 of the combustion chambers per rotor, x 2 rotors.

The bottom line is wanting it to be of smaller displacement is only because you and a lot of people seem to think that smaller displacement is better. Whatever. The laws of physics dont change becuase you dont understand the concept of rate and the fact that all the math out there is designed with a engine that must spin 720 degrees to fill every combustion chamber.

A rotary requires 1080 degrees, or three rotations of the eccentric shaft. But, is not a 3.9 liter engine? NO! THE RATE IS 720 DEGREES. If you change it to 360, so you can get your jollies of low displacement, all the piston engines are effectively half of what their manufacturers say they are, because its nonsensical to measure a 13b by a different rate than every other engine.

Rate being equally applied to all engines is essential because when youre measuring the POWER output of an engine. Power is rate of work. The rate that EVERYONE uses is 720 degrees. TWO rotations of the engine.

Let me put it this way. Rotaries AND piston engines dont fill all their cylinders and make power and spit it back out in 360 degrees, or one rotation, with the exception of 2stroke piston engines. A rotary has to spin its e shaft 3 times to fill. compress, combust, and exhaust all of its 6 combustion chambers. A piston engine (of whatever configuration) requires two.

But, because the math was done with piston engines, as the rotary wasnt yet developed, the rate is... 720 degrees. Thats the standard everyone goes by. So, you measure how much is moved in two rotations.

Get it? Because I dont even know where to begin explaining to you whats wrong with what you say about how it can flow enough air to spool up a big turbo without being a 2.6 liter, and about how the laws of physics apply just as equally to a rotary as it does to a piston engine... especially when rotary engines are INEFFICIENT compared to piston engines.

And finally...


How the hell is it moving about as much air as a 2.6 liter engine if its not a 2.6 liter engine?

[/QUOTE=AXMDR787BOY]Originally Posted by Nihilanthic
I have no idea what I'm talking about, but I'll throw my 2cc in anyway.[/QUOTE]

Look in a mirror, jackass. By the rate that everyone else goes by, which you dont get to decide, its a 2.6 liter, 4 combustion chamber engine. Why? Because while spinning at whatever rpms, the rate at which its measured (two) it sucks in air for 4 combustion chambers, squishes it, burns it (well, as much of it that it can) and then spits it out into its exhaust manifold.

Now, are we done with this? God. Displacement DOES matter, and the effective displacement of a rotary engine is twice what mazda says it is, and now its been explained why.

RX7skyline

Why not put a skyline engine in the rx7 it" has good power and very reliable i know i have it in my RX7

1984rx7

is that out of a probe?, also was there a probe that came with a stock turbo?

RX7skyline

1989 Ford Probe Gt Turbo

TurboIIRyan

no its out of a turbo thunderbird, and mustang svo. Iron block and head, but can make A SHITLOAD of horsepower and maintain it because the blocks are stupidly strong. The engines in the probe turbos are mazda F2's 2.2L sohc engines, making 145hp and 190ft-lbs tq

Nihilanthic

Im still tossing a 2.3 or v8 swap right now.. I wanna be able to put it in as-is at first and I Dont know if the alt and intake *a pipe goes over the valve cover* will clear the hood, buh.

I just might mangle the ******* hood and then put an aluminum one on it when I get a FMIC setup, lol.

BlastinSideways12A

Hope you like turbo lag if you expect to push respectable horsepower numbers.

I'm considering putting a Turbo II engine into a 240sx because it is a more respectable performance engine and reliable if built correctly. The FD's 13B-REW is even better than the Turbo II engine. Go figure.

Nihilanthic

Id go read up about 2.3s if I were you, before saying stuff like taht, because its not true.

Is 400 whp respectable? I can get that without lag with a properly sized EXPENSIVE turbo, or I can get a used holset and get it fine. Less than that in terms of power and its all even more responsive.

If I want to get a T-II, I have to spend the money to get a T-II. If I get a roller and convert to a 13B-REW, I still have to spend the initial cost, then do a turbo kit and all the other ****, and it will require rebuilds more frequently than a 2.3 turbo.

Also, a 2.3 I can run at relatively insane boost levels, and if i do knock while tuning I can back off - I dont have to utterly avoid it, at all times, tuning or driving, because its a VERY strong engine.

BTW, what do you mean about 'respectable'. A properly built KA-T can make tons of power. Do you mean about how a SR20 will be unable to spool as fast as a 13b if its making the same whp as a 13b?

MrDirt

I would have to agree that the SR20DET and 13BT are pretty comparable powerplants. I think I would still rather have a CA over an SR, though. Bad lag is usually only a result of poor turbo choice for the respective power levels.