302 question
 

So, if I swap a stock 302 (maybe minor mods), can I expect better overall speed than my previous 13b (1988 na, hks full exhaust, cold air, stage 2 porting) ?

Also, any recommendations for whether to go carb or efi?

stock 302, what year, what mods, I am guessing the car is a 2nd gen. What trans, why change it? Is the engine broken?

carb is easier, EFI is more driveable and marginally better economy

EFI is nicer but more work.

Pretty much any 302 is going to be putting out more power than a 13b NA unless you pick one from the 70s or early 80s.

just out of curiosity why would you put a 5.0? in and not the more modern 4.6? it would be about the same availability but smaller and more powerful than the old 5 liters!

The 4.6 is physically much larger than the 5.0. The overhead cams on the 4.6 account for much of the size difference vs. the in-block cam in the 5.0.

The 4.6 will fit in a 2nd gen, the one I saw had a bulging hood, which IMO looks like shit, don't know if it was necessary or not.

If you search the west for sale section there are pictures of one I believe from about 6 months ago.

Pretty much any V8 with the exception of some of the bone stock emissions restricted piles of shit out of the late 70's early 80's will make more street able power than a NA 13B, and they should no matter how you calculate it even a 302 has at almost twice the displacement.

Eh, you should stick with the 13b. Even if it makes less power, it is still quicker in the sense of power:weight ratios. And i thought that the rotary, being 1.3L was = 80cid, which then mathmatically the 302 would be almost 4x's more cubes.

I've had plenty of 302 powered farm trucks, and it is not worth the time to swap in. They are highly underpowered for their size. They like to gulp down the gas for their size(or the lack there of, compaired to how much they drink when running them hard) That is, unless you have a new cam, heads, intake and if not, you will have a good 1800-2000 wrapped up in buying them just to get 350-400 horses. EFI will make a bit more power mod for mod, but it also is a bit more expensive.

Really, unless you have a totalled out mustang just lying around, you are probably going to spend as much swapping that in, as what you could buy a tII s4/s5 engine/trans, and modify it some. Atleast those will drop in.

Just my 2 cents. I hope this doesn't lead to any flaming.

IMO you can call an a 13b a 1.3 liter rotary engine if you want. But in comparing its displacement to a piston engine, you can't simply ignore the number of revolutions. They have to be compared with the same test or not at all.

In other words if you rotate a 302 V8 through 1 crankshaft revolution, it will pull in 151 CI of fluid. A 13b through one eshaft revolution will pull in 80 cu of fluid, so in order to compare them strait across the rotary engine displacement should be doubled.

FWIW the Rx8's renesis motor won 2 engine of the year awards in the 2.5 - 3.0 class, so apparently I'm not the only person with this opinion.

http://rotarynews.com/node/view/379

If it where me I would also go for a 13B turbo certainly over a ford 5.0 or 4.6.

i did the 5.0 swap with a 93 mustang motor and converted it to carb with a different intake manifold and an edelbrock carb, and theres really no comparison. To be honest it doesnt really feel like i have an rx7 anymore. Totally different car now. Your gas mileage will go directly down the drain, but as far as power to weight...the 5.0 is larger but your net weight gain is only about 150 lbs, and doesnt really mess up your handling. You will spend a ton of money getting everything working properly on it..even if you go with the grannys kit that supplys most everything you need to get the motor in and the driveline hooked up. Just my 2 cents on the issue. I did the 5.0 and i wish i had gone ls1 or lt1..more bang for your buck and much more powerful engines

One thing to note, often times the mileage goes up on a V8 swap if you stick with EFI and a manual, but on a carb they probably will go down. So just to clarify if you went with an EFI 5.0 you shouldn't have that issue.

One nice thing about the 5.0 is the price. Complete blocks are generally so cheap to come by compared to an LSx, although you might be able to find a 350 for a similar price (with a carb). They don't make a lot of power but with an aggressive cam 300whp shouldn't be a problem. As other people said, a bone stock 5.0 in an FC will blow your current performance away. It isn't the horsepower (although there is more with the 5.0), it's the torque, you will definitely feel it.

Wow, lol. I was just throwing out some basic numbers. I didn't plan to get involved in this whole mathmatical thing. I honestly didn't know that the cubes should be 'doubled'. that is interesting. either way I am an aspiring convert. It only took one drive in a friends n/a and I was hooked. It wasn't even 'fast', just how it drove. the rpm's, sound, the power band up in the higher rpms. it was sporty. it wasn't an understeering nose heavy v8. *shrug*

I've had my share of 302/351w powered mustangs/fords. They take just as much money as the rotary to get power out of. They have no powered band, really. It comes up, then falls off.

I mean don't get me wrong, you get a 347(302 stroked), with heads, cam, intake, carb, lots of porting and time at the dyno, sure you get a nice fat powerband. but it is just as reliable, if not less than 13b-r. People are getting 80-100k out of em. They guzzle the gas, and they are heavy too.

You can build a 302 with the heads, and cam, but even then you are still looking at a bit of money. stock the engines aren't special. especially carbed. My 2.3T (ford 80's turbo 4cyl) would outrun stock-medium modded 5.0's. And that was with junkyard parts, and home style porting.

I'm not a v8 fan really. They are over rated. Today with the performance technology there are too many options to v8, to fall for the weight of that cast iron block(5.0), and coca-cola drinking habbits.

Just my personal view on it, and by no means am i attempting to provide fact, merely opinion. You're going to do what you want, and I hope you enjoy what you build. So, I hope no one starts a big arguement over anything i've said. Goodluck with your project.

IMO I wouldn't use the ford. When comes to bang for the buck you can't beat the chevy motors. You can go old school with a carb for super cheap and make good horsepower. Or, go a little newer with a GenII or LS based engine. They are plentiful and getting cheaper and cheaper.

I just got mine running and I couldn't be happier with it. Good luck :icon_tup:

As one of the first swapped RX7s in the US, I used a Ford 5.0. Mine was a modded engine that made nearly 400 hp out of 306 cid. Wide power band (3000-7000 rpm, but good power from idle), and I got 25mpg highway with the 4:11 rear gears and 23" tall tires.

http://www.supercars.net/pitlane/pics/484414b.jpg

The 4.6/5.4 is physically as large or larger than the old Ford 460, which is a good reason not to use it. I'd also not use an older Chevy 350, as it weighs another hundred lbs more than the Ford as well (my engine weighed about 400 lbs and retained the RX7s weight balance, with an all up weight of 2720 lbs with the addition of a 6 point roll cage). Though, I might go with an LT1/T56 if I were to do it again, as they are getting cheap enough, and with the aluminum heads and intake can weigh closer to the Ford.

Did you actually have it on a dyno?

How much power to the wheels.

I know a 5.0 is capable of 400 whp (NA) but I have never known anyone to make that much with one.

I have owned 2 5.0 powered vehicles, a 91 fox body, and a 91 crown vic.

Both cars had efi, and I could never get better than 22 mile per gallon HWY out of the fox body. It was mostly stock.

I would think that at this point rather then dumping 4K dollars into building a 400 whp capable 5.0, someone would be better off putting the money into a used LSX.

My buddy had it on a dyno when it was in his Fox Capri drag car (he was replacing it with a built 460, so I got it for a really good deal). It had made about 330 at the wheels, which was about 380 at the crank. Or almost 400 hp. Not bad for a naturally aspirated 306. It's all in the heads, with the ported small chamber 289 stuff, with 1.90/1.60 chevy valves, and in the modded carb (contrary to popular wisdom, it worked better with an oversized carb. The Holley was ported to flow 780 cfm... built by a local circle track racer so it would go around corners. I put a 700 cfm Edelbrock on it, but it wouldn't run at WOT, nor would it go around corners without starving so I went back to the Holley). It all worked because the RX7 has such short gears. When I had it in the RX7, the one time I had it at the drag strip, it ran an 11.72@ 115mph with the Holley. And I couldn't launch the car effectively (I'm not a drag racer).

I miss that car. Wish someone could find it for me (apparently the last owner I knew of put nitrous on it...).

Yes the weight issue does come into play, but from what I understood the positioning of the 350 with the Grannys kit (farther back and lower then the Ford kit) actually allows it to keep a pretty good factory balance. Even then, dropping the 350 in, drop in a good cam plus a stroker kit, replace the front suspension, and poof you have a car that is scary fast!

i think the big problem with SBC's is the rear mouted distributor. if you can relocate that and get the engine up against the firewall i think its a worthwhile swap.
and really, whats 150 extra lbs in an 11 second car?
its doesnt have to handle like a miata.. its just a car thats fun when you push the gas.

I built up a 302/5.0 because I have tinkered with foreign cars all my life, but never had a hot rodded V8. The whole swap thing was an interesting and very educational experience, but I made the mistake of thinking a carb would be much simpler than trying to figure out all the wiring for the fuel injection. It runs great, and I love driving it, but it took me a long time to get the engine and automatic trans to work together properly. If I had it to do again, I would get a compete donor car, Mustang, Z-28 or whatever, and transfer EVERYTHING into the RX-7, including the wiring. The fuel injection works better when cold, and definitely gives better fuel mileage. I recommend you look at Brad Bergholt's nice detailed writeup on Granny's web site, listed under "Smog Legal Conversion" for a 5.0.

If this is just for driving on the street, you certainly don't need 400 horsepower. I can outrun most cars from 40 to 70 on the freeway without shifting out of overdrive (4th gear), and I am getting about 250 Hp to the wheels. It is the torque that makes these cars fun to drive. Acceleration is not just a matter of peak horsepower.

There will always be more aftermarket parts available for a Chevy 350, but in recent years a lot of stuff has come available for the Ford, and the available power is pretty much proportional to the cubic inches, as equivalent cams, heads and other goodies are readily available. 5 years ago I estimated that it would cost me about $250 more to get the same power per cubic inch with the Ford, and it weighs 75 pounds less than the Chev 350. The weight is less of an issue with a 2nd gen car.

My current project is an FC with a 13b-rew, street legal in CA. On stock 13b-rew turbo's I make about 325 whp (the car show dyno showed way more than this but I know it's BS.) with very conservative tuning (I tuned on 89 octane with a knock sensor). With the sequential twin turbo's I have about 15 PSI of boost by 2500 rpm (depending on gear), which gives indredible (for a rotary) low speed performacne. Even if (big IF) my car could out perform an identical car with a stockish LSX, I would imagine that an LSX would be a hell of allot more fun to drive.

I like the rotary engine and the stuff that goes along with making one reliably perform well for the gadget factor (I like to tinker). But I can't help but thinking that rotary engines missed their mark. I think they would have been better off developed into replacements for the 2stroke market, and for light planes, rather than as car engines

My next project may well be an LSX miata, that is if it can be done without too many compromises.

no you have the backwards, the ford sits further back and down in the engine bay not the chevy, they chevy has to sit up and forward for distributer and oil pan clearance.

when using a ford you need to get the dual sump pan so it straddles the cross member and can sit down thats why they fit under stock hoods...

crap, I am thinking of a FB car....

I have an 86 GXL: bored out 302 to 317, rv cam, stage 2 stock heads on an Edelbrock 600 carb/ performer manifold, MSD 600 ignition, MSD distributor, on an AOD tranny w/ a Full race Trango shift kit, stock gears- can't recall the ratio.
Basic Granny's conversion kit.
Weight: skinned hood, battery relocated to the passenger compartment.
Sway bar set up w/ spacers.
255 40 17's in the front, 275 40 17's in the rear.

I live on one of the highest and most treacherous turning hills in my area - speed limit 35- car can handle 55 on it. Slight pushing but nothing major.

302 swap only adds about 50 lbs to the front over an 13b - and w/ the changes - and w/ aluminum heads you can offset the weight up front easily - 13b is a HEAVY motor.

My set up w/ Twisted wedge heads and you will have your 400 hp easy.

I like bottom end, so I don't need crazy heads.

350 adds about 150 to the front. Much heavier, bigger and not as much room to fit in the engine bay.

Not including the car: approx cost for swap - $2,800.00 -
Did own engine rebuild
Did all work myself.

Maybe this will help w/ your decision.


Overall impression:
People freak when they realize what it is. My car isn't exactly stock looking. :rlaugh:
Great conversation piece - be ready to do a lot of talking when parked.
Driving the car is freaken Awesome - sheer power when compared to my 13b. - but it was pure stock - before it blew an apex seal. - gotta be fair. :sad:



[IMG]http://i248.photobucket.com/albums/g...l/100_1356.jpg[/IMG]

[IMG]http://i248.photobucket.com/albums/g...s/100_1381.jpg[/IMG]

[IMG]http://i248.photobucket.com/albums/g...s/100_1382.jpg[/IMG]

Doesn't look like this anymore - dual air ram system on it now.

But thought you might want to see a couple pic's

I will say this, you will need to be creative. Stuff you wouldn't normally think of:
EX: Ford has the radiator cap on the radiator, Mazda had it on the block=no cap location.
see engine pic for the solution.:Wconfused
Or: - look at where my alternator wound up.
If you like having to figure stuff out like that, this would be a great project for you!!

Later,

TFitz.

FYI only 86 and 87 had no cap on the radiator....

Your figures got to be FWHP, right? I know people that have spent like 5K in parts, mods, and machining on a 5.0 and just cracked under 400 WHP and that was with cam and heads that made for a poor bottom end, though it was on a heavier car.

OH - and Merc63 - unless you are the guy who bought Chris Vetter's car, or just used his original information on the top of the pic you posted, dude- you totally ripped one of the most famous V8 Rx7's ever built and called it your own.
And being that you used a very famous pic of his car amongst the true RX7 V8 crowd, instead of using one of your own pic's, that defrauds you as well.
Bad move pal.
If you did actually buy Chris' car, he wants to buy it back. He has been looking for it for a long time.
And if it is your car, I recant my previous statements.

I remember seeing Merc post pics of that car a few years ago on v8rx7forum.com, so i'm pretty sure thats legit. i also remember chris' posts when i first joined... maybe he sold it right around then?

Only other thought, Merc63 changed his tag, and is actually Chris. That poor guy did nothing but want to help us fellow wanna be V8 noobs - at the time -, and he just got charcoal flamed in any chat he participated in.
He was one of my greatest inspirations to do this build to begin with.
Hope all is well with him.