jimlab

The conversion uses a chromemoly 1 7/8" torque arm, similar to the style used by the Camaro. The transmission is no longer suspended between the differential and the engine, using a standard T56 trans mount and a custom cross brace with an integrated driveshaft loop. The torque arm bolts to the differential and the cross brace.

I ditched the A/C and power steering, cruise, air bags, etc. long before I switched from rotary power, so those aren't a consideration. My only accessory is the alternator. The stock water pump is shaft driven (not belt) on the late-model LT1, but I've replaced it with a Meziere electric water pump.

I've also kept the stock gauges, but had the tachometer recalibrated for the V8 signal, and had the speedometer altered and recalibrated for 8,000 ppm @ 60 mph (instead of 8,200) which is the output of the GM PCM (powertrain control module). I also bumped up the top speed a little.

SPOautos

What about the Power Plant Frame??? How will that fit into the picture Jim??? Will you have to create a new one or try to make some kind of adapter bracket???


How long will it be before you have to have the rear? Is the car almost finished?

Later,

Mykl

It isn't very much fun to drag race a 16 second car at the track, all it does is wear down the components more quickly. If I had a turbo then perhaps it would be more fun. I could go out and buy an FD tomorrow if I wanted to, but my personal philosophy on driving keeps me bound to the n/a FC for a while longer. That and I'm having a good time humiliating all of my friends in their lighter weight, more powerful, modified cars on curvy roads with my out-dated, 13 year old, under-powered, over-weight sports car.

Jim, sorry if I came off as less than open minded this morning. I'm not really sure what I was thinking at the time. Logically, there's no point in keeping a rear end that you know is going to break, but you've already figured this much out. It's rare for me to offer a differing opinion on how something should be done without offering a feasible alternative solution of my own.

Actually, I think Magnificent 7 said what I was thinking better than I did.

It must be my time of the month or something.

jimlab

As mentioned above... torque arm.

The PPF is no longer used, since it only integrates with the OEM transmission and is the wrong length for the T56 anyway. A transmission cross brace is added and the T56 uses a standard Camaro-style transmission mount for support and is isolated from the differential. The torque arm, which is also modeled after the Camaro design bolts to the area of the differential where the PPF formerly did, and is a triangulated bar which is used to locate the differential laterally, and has the ability to (at least mine will be) adjust pinion angle vertically. It conects at the front to the transmission brace.

lesd

I like the Vette IRS plan. Kinda balances the car, Chevy front, Mazda middle, Chevy back !
It makes it even easier to claim 50/50 ratio, which we all know is such a hot topic around here, when doing swaps ;-)

-Les

jimlab

Mazda middle?

KZ1

I don't know Jim, your story is beginning to sound a little fishy.

In a previous post you said how you had built some huge piston engine, built ls1 I think, and then got rid of it,to get somethign better you mentioned here you had 20b and got rid of it, Who does this you are either the most indecisive and wealthy person on here, or something else is up. You talk again about having an IRS rear end, etc. and now you want to get rid of that. But you haev never used any of these things, neer put them in the car!!!

Why are you always saying you have bought like 4 of everything, I personally think your car will never get finished, b/c just before it it get's finished, you are goingto rip it all apart again.

jimlab

Maybe I'm the most indecisive and wealthy person on here...

Day one... April 4, 1997, 104 miles



My stock motor... April 1997, 104 miles



My non-sequential conversion with full mods... July 1997, ~4,000 miles



My first engine swap... September 1997, ~6,500 miles



My 3rd engine with 3mm ceramic seals... August 1998, ~13,108 miles



My 20B... May 1999, ~13,108 miles



My V8 engine cradle... November 2000, ~13,108 miles



My 1995 LT1 crate motor... January 2001, ~13,108 miles



The custom AFR heads for my latest motor, a 396 (6.5L) LT1, being built as we speak... October, 2001, *still* at 13,108 miles



I'm always saying that I've bought "like 4 of everything", because I have. I bought a Eagle 383 cast crank, a Cola 396 4340 forged crank, and finally a custom Crower ultralight 38 lb. crankshaft for $2,700 before I finalized on what I was building. I have three engine blocks, 2 sitting at my house. I have bought 3 cams, and we're still not on the final grind. I've bought 2 pairs of cylinder heads, 2 sets of connecting rods, 2 sets of pistons, 2 sets of valve covers, neither of which I'm going to be using. 2 oil pumps, 2 sets of lifters, 3 sets of valve springs, 2 sets of rocker arms, 5 sets of valves before I bought the set of Titanium valves that are going in the motor. 2 billet throttle bodies. I bought an LT4 intake, before we decided to have a custom intake made by Hogan Racing to match the custom Air Flow Research heads. And that's just the most recent V8 project.

I've had 2 sets of wheels, 4 sets of tires, 3 cat-back exhausts, 2 midpipes, 3 13B-REW engines, 1 20B, 2 V8s, 2 sets of sleek lights (and nearly a third), 2 sets of Japanese-spec tail lights, 2 rear wings, neither of which was ever put on the car, a full set of crossdrilled and slotted rotors which I just sold for a song, because I changed my mind and bought the AP Racing brake kit from N-Tech, which if you've been paying attention, I just put up for sale before even receiving it, because I've changed my mind YET AGAIN. And the list goes on...

I have receipts and hundreds of pictures taken since day one, if you'd like to review my project. And it is a project. This isn't a daily driver that I need to get back on the road. This is a car that's just been sitting around collecting dust since May of '98, and I tinker on it occasionally. You're right, at this rate, it may never be finished, but it's a hobby.

Now you were saying something about my story sounding a little fishy? At this point, I'm trying to figure out what to do with the differential to beef it up to handle the power. I haven't bought a Corvette IRS yet, or the Kaaz differential and 300M axles, or a 9" solid axle, because I'm still determining which direction I want to take. I talk about having an IRS rear end, because all 3rd gen. RX-7s have IRS rear suspensions. The question now is, what to do with it so that I don't leave a litter of parts and gear oil all over the ground.

Please try to pay better attention. I see by your post count that you have to have been around long enough to have followed at least some of my project and seen at least some of the pictures which back up my "fishy" story...

LUV94RX7

iTrader: (3)

To me your solution is easy. Go with the Kaaz and 300m axles. Do want I'm going to do. When my car is done it will have 400RWHP and a stock drive train. It will have lots of highway performance(60-90 in <3sec, 30-60 in <2sec).

I will not be doing standing starts with sticky tires and dumping the clutch at 6k rpms. I don't want anything to break.

Your car will have plenty of performance just taking off and flooring it.

Ken

jimlab

It's not my style to baby my cars. I may take good mechanical care of them, but I beat them like I stole them.

It looks like I'm going to go with the 300M axles and cryo-treat them, since it can't hurt, and replace my diff with the Kaaz unit. I like the idea of leaving the rear of the car "stock". I'll take the risk that they won't put up with the power. You should see what some of the blown LT1s do to their differentials just launching off a 3,500 rpm stall... when you're pulling the front wheels off the ground, *something* has to be taking a beating.

My best bet is probably just to let the tire be the limiting factor and not try to nail the car to the ground through the rubber. Rubber is cheap. I'm still interested in seeing if I can get a P315 on the back of the car without rolling the fender well or slapping some tacky "Pettit wide body" flares on it.

Magnificent 7

Hey Jim,

I didn't realize you're not using A/C. Does it ever get hot in the Northwest? It sure as hell does in Texas -- and add to that the fact that I'm a big fat sewaty bastard with a hairy back, and man I gotta have that A/C. The power steering is nice too. Anyway, since you have installed the engine can you tell me if there is room for the compressor and P/S unit? I know the plumbing can be worked out. The airbag well I don't know. Maybe I can live with out it (no pun intended).

Damn I wish I could do this mod now. Hell it would be worth it just to buy all of your discarded (unused) parts.

jimlab

The A/C never impressed me much, despite the car being new (and yes, the system was charged properly), so I had no regret in ditching the extra complexity and weight. I have all of the underdash components removed as well. Besides, we very rarely have days that peak in the 90s or higher, so it's not really necessary up here.

I'd also never go back to power steering. The car was much nicer to drive at speed without unwanted assist or isolation from road feedback.

But you can keep both, and Bill Hagen, who installed a stock LT1 with all accessories is probably the best one to talk to about adapting the GM accessories to the Mazda components. I don't have his e-mail off the top of my head, but you can probably contact him through Granny's Speed Shop (www.grannysspeedshop.com), where you can find details and pictures of his install.

jimlab

Just for laughs, I'm talking with someone who is developing a combination of the two... 9" Ford carrier and IRS...

KZ1

Okay Jim, Yes I have seen some of your previous stories,I didn;t say I didn;t beleive you, it juist strikes me as strange and I though I woudl mention something. You can understand that because well, what you are doing is rather unorthodox. More power to you Jim, I know all about hobbies, enjoy. I guess. My FD is not a daily driver either but it is a driver I just coudln't imagine not driving a car for 2 years. But hey, whatever you haev fun with.

ciao

BTW, that was some crazy chrome or polished aluminum on your 3rd engine.

jimlab

BTW, I'm not proud of the fact that it takes me so many attempts to arrive at what I end up with, but the fringe benefit is that a lot of people get head-to-head comparisons from my experience without having to buy any of it.

I bought the crate engine just to get things moving along, and figured I'd just put a cam in it and port the heads. Then I got a great deal on some AFR heads. Then I decided to rebuild the motor and build a 383 cid stroker, so I bought an Eagle cast 3.75" crankshaft and a set of Eagle 6.0" forged H-beam rods. Then I decided I should get a forged crank instead of a cast crankshaft for longevity, and figured if I was going to pay the $890 price tag for a Cola crank, I might as well go with a 396, which is the reasonable limit for longevity and power. I decided to go with a high lift cam that required +0.100" valves for the heads I had, so I bought those. Then I decided to go with bigger heads. So I sold the heads I'd bought to get bigger heads and got larger valves and springs in preperation for the bigger heads. Then I had to take the entire project away from the local engine shop which was doing the work, because they insisted that I'd never be able to run the compression I had on pump gas, and a few other issues they had which told me they knew nothing about the engine they were working on. So I ended up with a second block (in addition to the first from the crate motor, which I completely disassembled) clearanced for a stroker crank. So I found an engine builder in California, and instead of going to the pain and agony of trying to ship a block to him, I just had him pick one up, so now I have 3. At that point we started talking about my goals, and he suggested the route we eventually took, which was to have AFR custom cast heads to our specifications. At that point I ordered the custom ultralight crankshaft and rods from Crower to get quick revs. The valves I had were too small both from a lift perspective (we ended up going +0.300" on the valves) and we decided to use Titanium to ensure we could get the rpm and durability we wanted. The heads then required a custom intake manifold, and we decided to have Hogan Racing make one, because they build manifolds for many competitors in all the major NHRA classes. The JE pistons I had were no longer idea for what we were going to ask of the motor, so I now have a second set of custom JE forged pistons. I went with bigger injectors (50# vs. the 36# SVO injectors I had) and instead of using the GM PCM for engine control, bought the SEFI-8LO system to use in conjunction with it for the higher rpm capability. I ditched the 58mm billet throttle body I had bought from Holley for an Arizona Speed & Marine 1,300 cfm billet throttle body. As for the valve covers, the carbon fiber covers shown in the pictures above wouldn't clear my shaft rockers, and so I got a set of fabricated aluminum covers. Problem is both were centerbolt pattern, and AFR could only make my heads in perimeter bolt, so neither works. After buying 2 hydraulic roller cams and scrapping that idea because for a little more pain, a solid roller will make a lot more power, and a hydraulic lifter won't hold up to 7,000+ rpm, I had a cam ground, but as it turns out, we're going with a much larger custom grind (yet to be ground), and that one may not even be the one that ends up in the engine, after we start dyno tuning...

So you can see how things can quickly get out of hand when I can't make up my mind, or I'm getting advice from different sources.

rexman7

[QUOTE]Originally posted by jimlab
[B]
But trust that I won't put a solid axle under the back of the car unless there are no other options left.

yeah ,please go irs. what kind of irs did the shelby cobras use?
i know its old tech , but i would think w/ all the kits out there that it would be common. maybe a 9" center. dont know. but i would think w/ the right setup it could be made to handle good.
then again i dont know much.

ronarndt

Jim- Just curious why you did not pursue the 20B, other than your vendor problems. I'm kind of in the same boat, considering buying a 20B off-the-rack from Pettit or going for a Z06, like apparently you are doing. Price isn't that much different, but the esthetics are. On one hand, the FD has a certain "sleeper" factor which is hard to ignore. But then, almost every suburban housewife knows that a corvette is a fast car, and now with the Z06, Chevy has finally got their act together. I must confess I miss the sound of a well tuned V8 exhaust. Decisions, decisions.
Ron A.

80-CU.IN.T

That's a Hell of a lot of HP you will be putting to the ground.

I don't see how any IRS will be able to handle that amount of HP on a launch. "You have a bomb behind your butt. "

I would suggest a 9" W/ a 4 link.

"You are going to have to make up your mind as to if you want, a drag car or car for the twisties." I am not very enthusiastic about drag racing. Don't get me wrong it takes a Hell of a lot of skill but I have a drag race between every corner and then I can get sideways to if I want. Most of the time when I don't want to.

I would suggest keeping the car for what it was made to do, "Go around cornners." Your Z06 will not have even be able to touch it.

If you modify the IRS, slamming the gears up or down while moving shoul not be a problem. Just don't launch it.

You have an great project. I would very much like to hear what you decide to do.

I am trying to figure out how to upgrade my IRS also.

jimlab

Mostly because I refused to ruin the steering characteristics or weight of the vehicle... the 20B is heavy, despite what anyone tells you. Mine was 561 lbs. on its crate with turbos and most of the intake. My LT1 crate motor was 476 lbs. and that's with double accessories (extra parts thrown in). My motor has only the alternator as an accessory and has been reduced in weight substantially (18 lbs. in the crankshaft alone).

The 20B also requires relocating the steering rack or going with a dry-sump oiling system, which I also looked into. There was a dry sump setup for the 13G, apparently, but not for the 20B, and you'd have to make some parts and buy others. Mazda Comp quoted me around $3,500 for the parts. Relocating the steering rack introduces bump steer because the tie rods no longer follow the geometry of the upper control arms. They move at a different angle/rate, and when the car hits a bump, they will jerk the wheels as they try to cycle differently. Some say it's livable, (especially those people trying to sell you on a conversion) but I say it's a "hack", and refused to do it just for more power.

But bottom line is that when it comes right down to it, what you're really doing is replacing an engine with some inherent weaknesses with a bigger displacement version with the same inherent weaknesses. For the level of power I wanted, even a 20B would be taxed. The Cosmo was rated at 280ps, of course, but made about 300 horsepower in stock form, give or take. Pushing the motor to 500 horsepower is about the limit on "safe" use, and one of the reasons why the Banzai conversion stops there. Yes, you *can* get more horsepower out of the 20B, but at 700 hp, you're pushing it, and it won't hold up in a street motor. Most of the high horsepower 20Bs run alcohol for additional safety. You don't run alcohol in a street motor, obviously, and 110 and 104 octane are expensive. Replacing expensive parts with even more expensive and rarer parts to replace isn't a sound decision in my book, and planning for the eventuality that I'd lose an engine, it didn't make sense to go through with the 20B, so I sold mine.

I wanted to make around 700 horsepower on pump gas, without the complexity (or weight) of forced induction, day-in, day-out, with a more reliable drivetrain. It may not make it to 100k miles, but that's not a concern. I've never put more than 35k miles on a car that I've owned, and this one won't see 3,500 a year, probably. I won't ever have to worry about boost creep, octane level, excessive heat, and I'll be free forever of the "smoot" on the back of the car.

LUV94RX7

iTrader: (3)

Ya, so when will it be done????

XMAS???

Ken

jimlab

Unlikely... between the bushings and work, the holidays, and all the other crap of normal life, I haven't done anything on the car in over a month. Hogan Racing is just now building the intake, so the engine won't be assembled and dyno tested until December at the earliest. I'd say next Spring, but I'm not holding my breath. Too many things left to do, and still waiting on too many parts.

Want2race

Can i laugh when your dff bushings fail ??

just being a jerk.. Im in envy! Im not afraid to say it! I love what you are doing!!

Poindexter10thae

iTrader: (2)

Just wanna share a little old school darg knoweledge with you. I'm new to rotaries but I have been drag racing with chevy mouse motors longer than this forum has been around. Get a Ford 9-inch rear end. These can be built to order in almost any configuration and are (as much as I hate to say it) stronger than a GM 12 bolt any day. The main thing you need to figure out is the axle housings length(coming off the pumpkin).

newRX7fan

iTrader: (1)

Jim, I think I know the answer to this but I'll ask it anyway to make sure.

If someone else were to do an engine conversion such as you're doing, would it still be the case that it would take months and months (and months) to get all the parts and make everything work, even though you and Bill have already gone through this?

I think I remember you estimating a minimum cost of $6k (including a 'stock' level engine), is that still about right? How much more to get around 400 bhp?

My engine just blew an o-ring for no apparent reason, and my turbos and e-manifold need to be replaced- close to $6k right there, plus the possibility of toasting another engine sometime in the future.