QuagmireMan

for now my 12a with webber and other goodies is satisfying my need for speed, but once i get serious about this car ie repaint reattach body kit and maybe do the python fender flares... anyways im going to want a fast engine without spending mad money. So i was thinking of going V8 eventually, to those who have done their V8s how much did it cost you to put the engine in the car and did you do new rear end (i will i already lost one)?


PS for those of you who say pistons suck, your right but rotaries are too expensive to get high HP numbers. well to the V8 guys your going to hate me cuz i bet most of you guys are Ford guys well i want a 5.7 Chevy engine in there.

exodus82

If there is one, there is too many.

hornbm

There arent too many. However the best source I have seen on a V8 conversion is granny's speed shop. I dont remember theur website, but they seem to do this kind of swap all the time.

As for the ford vs chevy thing, I like most of the guys here dont lean one way or the other. When you break it down, there just about the same. Only difference is GM kept their designs standard, and ford changed it a whole bunch of times.

But quagmire! I just gotta ask.... why? putting a blowthrough turbo would be about as expensive as a v8 swap anway, probably cheaper.

Jeff20B

iTrader: (13)

A blow-through would be easier, and you'd get it done sooner. Ask DF.

QuagmireMan

a v8 will last alot longer than a 12a with boost, plus torque is so desirible... but it will be while before i do this, like maybe late summer .. .. and if i could but a turbo on my 12 for less than 500 i would do it.

Kerry

I've got a 5.0 in my 82. I'd recommend the Ford over the Chevy as it is 100lbs lighter. My weight distribution (with AC) is 51.5%/48.5%. You can find some good info here: http://www.torquecentral.com/forumdi...hp?forumid=11.

Kerry

cosmicbang

Are the people putting in v-8's using aluminum blocks?

Kerry

wish I could afford one. I'm hearing of some LS-1 and LT-1 swaps, but they're out of my league. I added 200lbs to the car (this includes an SE brake conversion + larger wheels & tires) weight distribution is about the same as an SE with air. With aluminum heads I could drop 100lbs.
Many people get over concerned about distribution, and Mazda fueled the fire by advertising 50/50 on the RX-7. I weighed mine before I started, and I can guarantee it was NOT 50/50 (with AC). My feeling is that the car is either nuetral or it's not. It's just easier to get it nuetral with equal distribution. Overall weight is more important. It's the mass you have to contend with to turn a corner.
I can live with the weight gain to have the torque, mine is a daily driver. Stop and go traffic sucks with an engine that doesn't like to run slow. And it's fun to sit there with the AC on and light the tires just by nudging the throttle.
Kerry

mar3

iTrader: (8)

Re: How many V8 sevens out there?

We need to know how long we'll need the salvage yard's car crusher machine....please report to DFW next weekend...

redrx

iTrader: (1)

If you have the dedication, it could be a nice end result, but If I wanted a V8 I would buy a used stang, camero, or vette.When I imagine the process of dropping in a v8 it seems like more trouble than its worth, but I dont know your abilites either...

rotor vs. piston

I have a chevy 5.7 with a T5 5 speed. As far as cost, if you take your time and source parts from "junk yards" ebay, and a bargin trader type mag. you could get a nice swap for about 2k. I (keep in mind I do have a chevy) would recommened going with a 5.0 with fuel injection. It would cost about the same (ford T5's are more common thus cheaper) and you would have a nice fuel injected engine.

Eville140

I'm not knocking anything, I like my swapped rx7. But got a question for you? How do you drop 100lbs by switching to alum. heads when a pair of iron heads don't weigh 100lbs to start with?

Also lt1 are still an iron block, the ls1 have the alum.

Later
Randy

Kerry

You're right... I never really gave it much thought. I've seen ads claiming "50 lbs lighter than stock..." and made an incorrect assumption that it was per head.

Allow me to rephrase: (clears throat) "I could lose some weight by using aluminum heads"

Kerry

rxcorv8

I have about $2400.00 in the entire car, including the cost of the vehicle, donor truck, engine and trans mounts, driveshaft, exhaust and other misc. parts. It took about 3 months of weekend work to get it running and on the road, I bought the car with no engine or trans and it had not been on the road in quite some time! I got it from a guy in Stone mtn. Ga. who was clearing out his stash of RX's. The engine is a 351w(Ford) and trans is the AOD. I have a 85 GSL rear and 205/55/15 on it. The tires were free or they would be 225/50/15 drag radials. The front has 195/50/15. When I got the car it already had O.Z. wheels. The engine fits under the hood with out any external mods. The rear end is realitivly safe due to tire size limits based on what will clear the wheel well. I have driven many RX-7s in their "natural" form and they are very much fun BUT there is somthing about a 2600lb rocket sled that can BLISTER the crap out of the tires through 3 gears not to mention the cost of the build can't be beat! I know this isn't the best place for v8 rx's but the bottom line is that we are all enjoying a great little car no matter what moves it!

white84GS

Why even put a V8 in a 7? It defeats the purpose of having a Mazda. Go out and buy a `69 Camaro and start fixing your V8 there. You'll make us 7 owners happy and my grandpa for bring back his baby.

hornbm

even if you find all the parts a blow through will cost still about the same, and probably less, and turbos make HELLA torque once they spool up.

Theres much more to do in a V8 swap, but if your hell bent on doing it, more power to ya man.

peejay

Aluminum blocks save maybe 50lb, maybe. It's a lot more trouble than it is worth unless the engine you are using already *is* aluminum block.

A 302 block weighs 135lb, and it's made out of decent metal.

My pet concept, which I was pontificating to j9fd3s yesterday, was that if people put a pig of an engine like a small block Chevy and it works OK... see, originally I was sitting there on the terlet reading an old CC article about a 427ci stroker setup for a 351W. (Which is still lighter than a SBC and it's still made out of quality iron instead of low-nickel putty) Basically you take a 400M crank, offset-grind it roughly .125", modify the hell out of some Chrysler 360 rods, add a set of long-rod SBC 383 pistons (now widely available, no customs needed) and you have a rather expensive, due to the machining, lowish power, due to the stock cylinder heads, high torque, due to the displacement, engine for the ol RX-7.

Well, hmm. If I am already thinking along those lines, I can do it much cheaper.

What engine weighs within 20-30lb of a small block Chevy, is factory machined to high standards, made out of very high quality material, is common as mud (and therefore inexpensive) because it rarely if ever fails in service, already has "sufficient" displacement (no big $$$ needed in machining a stroker setup), and can easily be built to make absurd amounts of HP and God's own torque?

Cadillac 472/500.

Just imagine... 450hp, 650lb-ft of torque, in a 2500lb car, with 2.73 gears out back (courtesy Fox-body Mustang 8.8). Hell, even a three-speed automatic would be two more gears than it'd need!

When I came to that logical conclusion, I could *not* stop giggling. I need to do this. This can, and will, kick ***. (But the bridge ported 12A comes first, since I have played with big-blocks before, and it's EVEN MORE ADDICTIVE than rotary power)

- Pete (Small block engines are fine... if you have a motorcycle)

j9fd3s

iTrader: (3)

yeah the caddy motor is too cool not to do

peejay

Well, sometimes even a small block isn't enough motor for a motorcycle....



(more pix and a video at http://www.bigbikeriders.com/48cyl.htm )

gamble302

hahahaha
those wheels you have probably arent the lightest man, they look cool though. se stuff is a bit heavier as well.
i think i could live with 200lbs extra for a motor that can reliably make a little over 350hp to the wheels, NA, on the stock block (although some weight would be shed with the heads required for that hehe)

gamble

rotarydankus again

iv e got a 32 valve 300 horse lexus out of a sc 400. the engine is 27''' long 24 wide and 23.5 bootem of pan to top of intake, with the 4 sp auto it ads 165lbs over 12a nd 5spd, dare me to slam it into mellow yellow, and i can do it in 30 days, and have less than 1650 in whole deal,

KehoeAutomotive

I have a wrecked Grand National sitting in the driveway.


I'm tempted to install it, Very tempted.

mar3

iTrader: (8)

Now, the GN swap would be one I wouldn't mind seeing since it's still a small cube, turbo'd monster pushing a lightweight body...the spirit of Mazda is still in that idea vs. cubic inches for HP/tq, ie. musclecar which is not in the spirit of the RX-7....

85rotarypower

Well, the GN makes more power than most 80's V8's in a much smaller and lighter package. they do the quarter in 13.5 sec. stock. Thats in a car about 800 pounds heavyer. They have the potential to do 10's with about 500hp with a few mods. 350 hp is very realistic for a GN by just turning up the boost. They can also make as much torque if not more torque than a SBC or ford.

12abridgeport

A GN motor powered rx7 has been my dream since the first time i've seen one at the track...it was a red 2nd gen with n/a hood, stock mufflers, and looked pretty much all stock except for one boost gauge and slicks in the back. When it took off no one could even hear it, that's how silent it was.

It was racing an LS1 firebird and totally sucked it up through intake and spitted it out the exhaust with an easy mid 12 second pass. Everybody on the benches was amazed and taken by surprise. I LOVE sleepers!!!