jimlab

I seriously doubt my differential bushings are going to fail... look who you're talking to...

http://home.earthlink.net/~jimlab

jimlab

My delays are mainly due to custom fabricated parts. When you're having a company cast you one-off aluminum cylinder heads and another fabricate a one-off sheet aluminum intake, it takes awhile.

Bill dropped a stock LT1 and T56 into his car and had it up and running very quickly, and he was the first to go through all of the issues of integration with the stock climate control system (A/C) and power steering, among other things, including passing emissions.

You can probably do it for $5k or less, if you can do most of the work yourself and find a good deal on the powertrain, which is pretty common. There are engines with transmissions regularly for around $2,300-2,500, and you can get a good drivetrain from a wrecked donor car at auction even cheaper.

400 bhp at the flywheel, I'm assuming? Some head work, a cam, and a throttle body, although the TB isn't absolutely necessary. In fact, you can make a lot of power with the stock heads, but it will require a cam change to really change the characteristics of the engine and create more power.

A good port job, a Comp Cams CC305 cam (emissions legal) and a Holley (or other manufacturer's) 58mm TB will get you 400 bhp fairly easily. Add a set of Comp Cams Pro Mag roller rockers and bump up to a CC306 cam (won't pass emissions) and you can push 400-425 RWHP as easily.

Check out www.camaroZ28.com for information on moddifying the LT1 (and LS1) for more power. You should easily be able to find results and recommendations for many combinations of modifications to make the power you're looking for.

Sounds like you're a likely candidate, then. If you have any other questions, just let me know.

jimlab

Can't argue with results...



This is an estimate only, porting has not been fully completed yet, and there is no flow data yet for the custom intake manifold. Also, this cam profile was selected for maximum drivability... I may give up a little manners for a bit more power.

Note that torque is 398 ft. lbs. @ 2,000 rpm, and doesn't fall below 400 ft lbs. until 8,000 rpm... 6,000 rpm is a VERY broad power band. 557 ft. lbs. @ 5,000 rpm peak.

This graph also shows power peaking at 639 horsepower @ 6,500 rpm, but note that the engine is still making over 500 horsepower @ 9,000 rpm.

We'll shift power up the scale a little with a little more aggressive cam profile, "sacrifice" a little low end torque to allow the car a better chance of A) hooking up, and B) not breaking ****, and bump horsepower peak a little farther towards 7,500 rpm and the 8k "redline".

The heads are already flowing around 325 cfm @ 0.650" of lift on the intake runner (and we're lifting closer to 0.700") but will be ported still farther for improved flow while retaining good air velocity. These figures were also obtained by using the characteristics of a ported LT4 intake manifold, and the Hogan manifold will be a significant improvement. Nice.

APU6speed

Hi Jim, long time no talk. (BTW my RX-7 was sold and is now somewhere in Washinton State) I would say go with the KAAZ and the 300M. Have you considered maybe using a torque management program like the vette uses? Maybe a little electronic black magic to help initally control the torque? Just throwing things out at ya so you keep the Mazda set-up. Good luck.

Lane

jimlab

Of course I care. Not that I have any intention of autocrossing or attending many track events, but you don't have to participate in either to care about the handling of the car. I would not have gone to such great lengths to ensure that the steering rack remained in the same location as OEM if I didn't care about the handling of the car. I wouldn't have developed the bushings if I didn't care about the handling of the car. And I wouldn't have removed so much weight at such great expense if I didn't care about the handling and balance of the car...

Trust me, I could have used a perfectly good $700 Eagle forged crankshaft instead of a $2,700 Crower ultralight 38 lb. crankshaft and had basically the same results. The difference? About 18 lbs. If that's not dedication to keeping weight the same or lower than stock, then I don't know what is.

newRX7fan

iTrader: (1)

My god Jim, 11,000 rpm? I'd like to hear what that sounds like....

You want me to ask questions here or should I PM you?

Mr. Stock

Jim,
Are you doing most of the work yourself in your garage?

Ed

jimlab

All but the building of the engine.

jimlab

E-mail me at jimlab@earthlink.net because I don't check my PM very often.

The motor won't see 11,000 rpm, not because it wasn't built to take it (10,000 rpm, anyway) but because it's unnecessary. RPM for the sole sake of RPM isn't useful. RPM is only necessary when small displacement and lower flow numbers through the intake components dictate spinning faster to pull more air into the engine. When you have heads that outflow (325+ cfm) many heavily ported big block heads, 2.10" intake and 1.60" exhaust valves (the biggest valves you can put in a small block head, BTW), a 1,300 cfm monoblade throttle body, and a fabricated sheet metal intake, you can pull all the air you want into the motor, especially with a cam which specs into the range of 0.650-0.700" of lift. You'll notice that the intake will hit positive pressure (and better than 100% volumetric efficiency) through part of its range.

Consider that the Viper GTS makes 500 horsepower (or will shortly) below its redline of 6,000 rpm, has 6 gears, and is for all intents and purposes the fastest and quickest street car with significant production numbers. A recent shootout between an '00 GTS and an '01 Z06 Corvette resulted in 12.40s for the Corvette, and an 11.9 for the Viper before it headed home. Definitely no slouch, and more than a match for almost anything. That's with stock tires, BTW, not slicks or drag radials.

Now consider that you have a car that is 500+ lbs. lighter than the Viper (~3,300 lbs. vs. ~2,750 lbs.), makes more horsepower and torque than the Viper's 8.0 liter V10 from "only" 396 cubic inches (6.5 liters), across a wider power band, and can easily spin an extra 2,000 rpm in each gear, and 3,000 if we wanted it or if it were necessary, *and* it'll rev much faster... would you consider at that point that you had something pretty capable of kicking the *** of anything on the street?

So the extra couple thou of RPM are just icing on the cake, and there's no need to go any higher than about 8,000 rpm. I chose that limit for a reason, not the least of which was that I didn't feel like having my tach face reprinted at the same cost as my speedo. I wanted to remain fairly true to the nature of the car, and as you can see from the graph, the redline is identical, and with a shift towards high rpm power, the horsepower curve is fairly similar to what you'd see from a single turbo rotary. The torque, on the other hand, you probably won't find the equivalent of in the rotary world.

LT1-7

hey Jim, when are you going to have your car up? I think I'm going to have to pick up the subframe kit since they are taking there time on shipping it out. I might want to stop by and see your car. Will it be up soon?

jimlab

My car won't be up for awhile. The engine will have assembly completed in December, probably and dyno tuned before the end of the month, with any luck. I'll get it in January, probably. After that, there's only... 100 or so other things to get done.

Rotaree

If you haven't already decided about a rear end...have you considered a Jaguar IRS? I've seen many cars with big power levels, especially the Cobra Kits Cars and Street Rods, use this rear end with great results. Just another option.

newRX7fan

iTrader: (1)

Yah, I didn't think you'd be using or need to use it to 11krpm, its just seeing a dyno plot that goes to 11k when most of them only go to 7 or 8k is something I don't think I've ever seen.

jcochran

Jim,

Viper tuners may have the answer about the replacement rear-end for your 7 (if you haven't already looked their way).
I've seen several instances of Vipers pushing 800+ HP and torque through the stock IRS. The usual required upgrade for these power levels was to beef up the half-shafts (a hard launch on a stock Viper with drag slicks would shred a OEM half-shaft). I've briefly looked into what common Viper tuners do to the rear-end for their hipo upgrades, but don't see much of anything. TNT, Hennessey, Doug Levin, BTR, SVS, and Golden West all show the same thing - no major rear end changes required. I suspect that you could contact Jon Brobst - the ViperGuru - about the specifications of the Dana diff and the other IRS parts. Hell, since he now owns www.PartsRack.com and buys wrecked Vipers, he could probably hook you up with a great deal on a used IRS.

BTW: the Viper guys swear on T. Welch's BTR severe duty half-shafts. Tom even money back guarantees the damned things.

James
Also in Redmond, WA

martini

That's not a real dyno plot, just a simulation based on flow numbers, etc.

jimlab

Thanks for the tip! I've also found another place that builds Jag IRS kits for Cobra replicas. They have inboard and outboard brake mounting options and various other configurations. My only problem is keeping the ABS intact.

The Supra/RX-7 on the cover of Turbo magazine mentions titanium axle replacements among its mods. Wonder how they came up with that and whether or not they're tough enough. Could save a few more pounds, though.

the_glass_man

iTrader: (2)

Speakig of saving a few pounds. You know what else would save some pounds? A sleek headlight kit Did you start anything yet? Did you decide which housings you are going to use?

jimlab

I've been talking to a few people and actually tracked down someone who can do a glass OEM-style "pod". However, I have engine and brake system issues to work on, and headlights take a back seat to that...

Brad

Totally off the subject...but just something I have to ask...

Let's go back 4-5 years to the day you bought your car, Jim. Pretend I'm there and said to you, "Ya know Jim...I dunno bout this whole rotary engine thing...whaddya say we try and put a 650 bhp naturally aspirated 396 cid LT1 in there???" What would your response be?

Just curious...

jimlab

I doubt I would have cared. I didn't buy the car because it was rotary powered, I bought it because it looked good and was fairly fast.

The fact that it was a rotary powered car still means nothing to me. The car still looks good, and I'm just making it faster.