website:www.grannysspeedshop.com
...Ordering Information...
The purpose of this guide is to lay down the necessary tasks in an orderly fashion, to hopefully minimize the
time and effort required to pull off a successful COMPLETE conversion.
Many, if not most of the steps described here, are the same regardless of the engine
choice. Injected engines such as the TBI, TPI, Vortec and LT1 will differ mostly with regards to
electrical connections and fuel system plumbing. The main mechanical components and
basic proceedures are generally the same.
If you would like more info on completing a smog legal conversion in California, CLICK HERE
Additions and corrections to this guide are encouraged, and will hopefully result in an
evolutionary process that will eventually include EVERY detail required, right down to
the wrench type, sizes, torque specifications and parts required to carry out each
individual step.
Often times projects such as this are undertaken without a full understanding of
what is involved. Hopefully, this summary of the steps necessary will provide individuals
with the insight necessary to evaluate their own abilities, and help them come up with
accurate estimates for both time and cost. Most hot rodder types will not need these instructions,
but if they encounter a problem at some point, it's nice to know that helpful information is a close as their computer.
This is a very easy swap that can be executed successfully by the average shade tree mechanic. No special mechanical skills or tools are required.
Effects On Maintenence & Reliability...
...If you already own a 2nd gen RX-7, then you already know about the rotary’s
maintenance requirements, have probably heard stories about dealer service
departments that lack proper training on rotary engines, and chances are, your beautiful
RX-7 is probably on it’s 2nd or 3rd engine by now. The RX-7 has not
been sold in the US since 1995, and replacement parts are getting scarce.
The Chevy engines, on the other hand, is perhaps the most common engines on the
planet. Most any person with automotive experience has worked on one, and a large
factory trained network of technicians exist from coast to coast. The modern Chevy
engine routinely goes 100k between tune-ups, and replacement parts are among the
cheapest and most common.
Effects On Performance...
...As you might suspect, the switch to an LS1 powerplant has an effect on
performance too. The additional low-end torque makes the RX-7 very easy to drive, and
is available throughout the RPM range. No longer will you have to excessively slip the
clutch at a stop light to keep from killing the engine. No longer do you have to downshift,
wait for your RPMs to come up (or boost to build) to pass a car. No longer will you live
in constant fear of the dreaded carbon lock. With the LS1, your power is always available.
If and when it comes time for an upgrade, things can really get interesting. Simple
$100. modifications can result in 15-20hp increases, while spending a mere $2500. can
get you up to around 500hp level. We are seeing low 12 second 1/4mi times from stock smog legal engines, which is much better than the 13 second
times that were possible with the 3rd gen RX-7’s stock turbo rotary engine.
Another consideration is fuel economy. If you've ever driven a rotary car for more than a few miles, you quickly realized that they do not get very good fuel mileage. The best is usually around 16mpg. Simply switching to an LS1/T56 will jump that to around 25mpg. That's with a "pass smog in California" LS1 that has nearly 400hp in an ultra reliable completely stock configuration, installed a car that is likely to be lighter than when it was rotary powered. It's pretty hard to see a downside here...
Effects On Weight, Balance, and Handling...
...This is where you probably expected there to be a downside. People have
probably told you that your handling and perfect weight distribution will be ruined with
the addition of that big, heavy, american V-8. Just ask yourself if any of those so-called
experts you have been talking to have any actual experience with piston-powered RX-7s.
We’ve got the numbers to prove all those bystanders and spectators are just
that....bystanders and spectators.
Here are some real numbers from a typical 2nd gen RX-7 converted to Chevy
power:
The example car is an ‘86, which was not lightened in any way. The car was
converted using an LS1 engine & T-56 transmission. It has a full stock interior,
as well as the stock air
conditioning and power steering. The stock RX-7 cooling system was re-located but retained. The battery was relocated to rear area just in front of the
tail lites. With a full tank of fuel, the balance is actually rear heavy. Considering that the LS1 has an aluminum block and heads, and a plastic intake manifold, there is a good chance that your Rx-7 will actually be lighter with an LS1.
Skills Required...
...If you have a good grasp of things mechanical, do all your own automotive
maintenance, have a good selection of tools and know how to use them, you are probably
qualified to perform this swap.
Estimating Time For Completion...
...We have broken the conversion process down into smaller steps (links listed below). This allows the person actually doing the conversion to
estimate the time he should allow depending on his abilities and resources.
Can I Use a Truck 5.3?...
The truck engines can be had pretty cheap, but they will not fit the RX-7's engine bay without some pretty big changes...
...the truck intake is too tall (need LS1 or LS6 intake, injectors, fuel rail, and different injector plugs)
...the truck oil pan is too deep (you need a Camaro LS1 pan/pick-up tube/tray)
...the truck alternator will hit the hood (need to fab bracket to lead alt over and use smaller Camaro alt)
...the truck upper rad hose interferes the LS1/2/6 throttle body (not easy to solve)
...truck ignition works great, but won't work with Corvette engine covers
...truck exhaust manifolds will not fit the RX-7 chassis ('02-up Camaro manifolds preferred)
2....Considerations & Requirements....
4....Engine / Transmission Installation....
5....Exhaust / Throttle Cable / Accessory Drive / Pulleys....
6....Cooling / Fuel Systems....
7....RX-7 Wiring Harness Connector ID and Circuit Locations....
8....Electrical System Modifications By Circuit....