I’ve been doing a lot of research and have finally decided to roll the dice on a unique LT1 build that has never been done before. I plan on road racing my 1997 Camaro and would like your help with selecting the best components for my application.

I’ve looked all over the internet and noticed one thing that really stands out on every LS1 dyno graph I can find. LS1 engine torque and horsepower always cross at 5250 rpms. My plan is to retro fit an LT1 Optispark onto a LS style block. This will allow me to mechanically shift the entire power band down so that horsepower and torque cross at 2250 rpms. This will have several benefits. By reducing the entire rpm range, I will be able to run a much larger 4.5” stroke. This has the added benefit of using shorter 5.5” rods for reduced weight and helps keep the compression down under 13:1 so I can still run 87 octane for daily driving. See the sample graph below:


I need the engine to be light, but not too light. I plan on converting a set of L31 Vortec cast iron heads to reverse flow cooling to handle the bump in compression. I’m also working on a custom cast iron intake with dual throttle bodies that will allow me to tune the runner length for optimal flow in the new operating rpm range.



Some extra weight savings will also be achieved by switching to a cast iron Powerglide transmission. With a 2.73 rear gear and 33” tall tires, the car should do about 25mph at idle, but still hit 125mph in high gear for top end blasts down the interstate. I’ve run multiple simulations in Gran Turismo to back this up and I’m confident I’m on the right track here.

Should I run a vented or non-vented style Optispark? I’m worried that the vented Optispark may lower engine vacuum and hurt drivability for my build.

Does anyone know which ECM supports an Optispark and drive by wire throttle body? I use the cruise control a lot and the increased throttle response would be nice.

Who makes off the shelf retrofit push rods for L31 heads on a LS block? I’m wanting to retain the factory stamped steel rockers to dampen valve train noise. Both of the front door speakers are blown in my Camaro and I want to still be able to hear the radio while driving.

Last, but not least….What cam would you recommend for a 462ci motor that peaks around 3500 rpms and gets equal or improved gas mileage over a stock engine?

Thanks!

 

I rate this post a perfect 5/7

First of all, you must consult Phoenix'97 because he has done much of the legwork already.

If you're still looking for additional advice:
All motors on earth will cross HP and TQ at around 5250 RPM and this is due to those idiots using the spherical earth model in favor of the much superior flat earth model. Don't fall for this because the design keeps you from experiencing true flatness. You're also not lowering the cross enough which ideally needs to be at the RPM while the starter is cranking it.

The L31 heads will be fine but you need to run them backwards (intake out, exhaust in) like some racers did on the old Buick nail head motors

Your simulation is sorely outdated. If you're staying with the Sony platform, please upgrade to at least GT3 A-SPEC or preferably GT4. Forza 2 mechanics are STRONGLY recommended.

The optispark should be of a non-vented type because airflow through the cap will cause too much turbulence to fire reliably.

You won't find a supplier for push rods so it's advisable to convert to SOHC. DOHC will be very unnecessary and just add to the weight and overall complexity. Might I suggest the rotary cam setup by Coates so setting valve lash and spring height can be avoided altogether.

As to your mileage question; have you looked into dark matter? Although it's incredibly dense and will add significantly to the weight of the vehicle, your engine will produce so much more torque that it will instantly move the entire universe instead of the actual car. Your choice of tire will be important here so I highly recommend the Supermax TM-1 205/55r16 which are on sale at Wal-Mart for $41.95

 

Epic greatness

 

Several other people at the last Flat Earther convention I attended suggested the same thing. I briefly considered running a reduction gear on the Optispark to lower the tq/hp cross even further, but remember that this is going to be a road racing car that I daily drive as my sole source of transportation. Lowering the cross to what you suggest would require a pinion gear larger than the ring gear to reduce torque output to something more manageable. My current plan with 2.73 gears and 33" tall tires would put the car at 25mph while idling. Going with your idea, a 0.75 ring gear would drive the car 65mph at idle. I'll have to simulate the high gear 458mph top speed in Gran Turismo to see how it affects my lap times before completely ruling it out, but I don't think I could afford the speeding tickets I would get for idling by the cops at 65mph in low.

This won't be possible since I must run all factory exhaust for emissions purposes.

I hadn't thought of turbulence. I'm glad you brought that up because I've had several people criticize my choice of cast iron heads and intake plenums. This was deliberate on my part to maximize air velocity. We all know that hot air has more velocity and will therefore fill the cylinders faster than dense turbulent cold air. Traditional high revving engines have less time to fill the cylinders, so cold dense air must be used. Lowering the entire rpm range of the engine allows me to turn heat soak to my advantage by providing ample time to quickly fill the cylinders with hot high velocity air.

I've posted these questions on many other forums and plan on ignoring any advice that doesn't fit my narrative. Suggesting overhead valves just exposes your ignorance. I have already been contacted by a gentleman on a Mustang forum that is currently working on prototype push rods as we speak.


I fully intend on achieving my goals with 87 octane fuel. I don't believe dark matter is legal in California and I must keep emissions in mind for this build.

Thanks!

 

 

If the end result does not look like this, OP, you’re doing it wrong:

 

Is this a relation of Phoenix? Either way...time for some

 

After untold hours of simulations in my mother's basement, I believe I may have stumbled on to something. Money is no object with this build, but I don't mind cutting a few corners in areas that don't significantly contribute to my overall goals for the project. I was fixated on running custom 5.5" rods with stock pistons, but simulation after simulation proved to be a major disappointment. It wasn't until I stumbled on to a used set of 5" 302 rods that the magic started to happen.

This required some out of the box thinking on my part. Normally I try to keep my stroke to rod ratio as close to 1 as possible for the scavenging benefits. Using stock 302 rods I got the ratio I wanted, but compression took a huge hit. Then an idea hit me like a bolt of lightning...Stock rods with custom pistons! I quickly sketched out my idea and will most likely be applying for a patent before I can show a full proof of concept to you guys. I've come up with a new type of piston that I'm tentatively calling a "coned piston". The idea is to add material to the top of the piston in a "cone" type shape to raise compression while using the stock 302 Ford rods. As you can see from the diagram marked in red below, minor trimming of the cylinder skirt may be required. The piston "cone" marked in blue allows for the proper compression in a large stroke, short rod combination. As an added bonus and cost savings, the head gasket can be eliminated completely!! The "coned piston" creates the perfect compression and quench to fill what's left of the cylinder with hot, high velocity air!

 

This is hardly funny and the sense of humor with regards to what I want to do with my car is quite dumb at best. Attention those seeking help on LS1 tech, this group is a joke! Spread the word!

 

My methods may be unconventional, but inverse quench technology is no joke sir!

 

The joke is all you! I am glad for that. You are deliberately making crap up and trolling, especially with this thread. I am glad! It never was me that was the problem, it is members like you.

 

I bet you are a hoot at partys.

 

I must warn you that I have a medical condition that requires I always have the last reply in every conversation. If you have nothing constructive to add, please avoid responding to my threads as I have from yours.

 

With the right connections and for the right price, you can get a take-off Flux Capacitor from a parted out DeLorean. Try searching the dark web for the next auction.

 

See?! Space isnt real guys

 

I got to say i found it to be hilarious.

I got to wonder how many people need to tell you that your idea sucks before you come to terms with it. People started out trying to help you and point you better direction you absolutely refuse to take a single piece . Why even bother starting treads asking for advice then ignoring people's advice?

 

*gets out popcorn

 

Nicely done.

KW

 

Can I interest you in an infinitely adjustable timing set? I took it out of my 94 Z28 when I went back to a fixed unit. This sounds like a perfect use-case for it.

 

Finally someone who gets it!!! Cam timing will be essential in this new build and I will need all the adjust-ability I can get. To this end, I have been contacting various cam companies asking their input. A couple refused to listen to my overall vision, some said it couldn't be done, while others merely laughed me off the phone. It took some time to build a relationship, but I finally found a contact who understands and appreciates the complexity of what I'm trying to accomplish here. I've been on the phone with him most of the day discussing some of the latest cam lobes and profiles that John Deere has to offer and I think things are finally starting to come together!