Help needed from propane experts! Custom V8 Propane Turbo Performance Setup

[Christ]

Sounds like you've got the idea. Start a project thread!

[xtian999]

The conversions I have seen work like SCUBA regulators. The difference b/w ambient and manifold pres is critical. I saw an ultra high performance lng powered drag boat that had a roots blown big block ford motor that was draw through style. The guy said he could run more boost/compression than a gas motor b/c of the higher octane, but the power was 20% lower b/c of the fuel's caloric value.

The old hot rod books had a volume on nitrous that told which fuels were best in combination. LNG likes everything. Methanol to cool the cylinders, nitrous oxide, H3O before or after combustion to pump up turbo exhaust volume, and tolulene/benzine/kerosene for grins.

You may consider a diesel motor as a base, since they have big displacements, higher compression, and usually come with turbo plumbing already. Thicker cylinder walls are good too b/c LNG burns hotter than gasoline and strips the lubrication from the rings and increases cylinder wear. Plus the diesels have robust bottom ends. Once you get it sorted out for lng, add nitrous to spin bigger turbos up.

Plus, you will be smog and perhaps hov lane exempt. No egr or cats, and you can fill up at your house. (no road tax)

[xtian999]

If you used a little computer like the Arduino or an Atmel chip, you could use nitrous solenoids or even lawn sprinkler heads to mete the flow with a pwm signal and run it like a direct port injection system. That would mess with some minds.

[mikernet]

xtian:

I'm not going to be running any NOS or anything like that. I don't want to have to refill bottles, and I want power that is always available. While I'm sure I'll hit the drag strip often, the focus of all my mods is auto-cross/road racing.

The ECU is a completely custom creation, so I can drive or read any kind of signal without a problem. I'm running all Freescale ICs at the moment, and they have a solution for just about everything automotive related.

Are you saying I would be smog exempt because of the diesel motor base, or because of the propane? Not having to run cats would be sweet. Keep in mind I'm in Ontario, Canada. I haven't looked up much related to smog law yet, but from what I can tell I'm still going to have to e-test.

The car I have is a 1989 Trans Am, which is slightly unfortunate because it will always need to be e-tested. 1987 and earlier cars are exempt from e-testing. They changed the rolling 20 year rule last year, so every car that still had to be e-tested will need to be e-tested forever I'm considering finding a 1987 rolling frame to build off of instead.

EGR won't be there regardless of whether I'm exempt or not...just a risk I'm going to have to take. There's no way I'm going to run all the EGR plumbing on the new motor build.

Diesel motor: I don't want a higher base compression than 10 or 11:1 anyway, so a gasoline motor would be fine in that regard. If I go any higher then I wouldn't be able to run as much boost. I believe HD-5 automotive propane has an octane rating of "only" 104 or 105, and I plan on running at least 16psi of boost, preferably more.

As I said in a previous post, direct injection might be sort of cool, but I just dislike the whole spotaneous combustion thing. I prefer the idea of controlling combustion timing with a spark for whatever reason.

Turbo plumbing is going to be completely custom anyway - the size of the turbos I'm planning to use won't let me reuse any stock piping even if I wanted to.

The LS3 I was planning to use is all aluminium. Aluminium dissipates heat much faster than cast iron, which I assume (although I could be completely wrong) is a good thing for the hotter burning propane.

I'm still stuck trying to decide where to inject the propane. I could do multi-port injection, with liquid injectors, but I hear that can cause burned pistons due to uneven mixing. When it is injected so close to the valves it doesn't have sufficient time to completely vaporize and mix evenly.

I like the idea of injecting pre-turbo but the possibility of backfiring during an engine misfire and blowing off the intake pipes still scares me. I'm also slightly worried that if a boost leak were to form somewhere, it would be leaking fuel/air under the hood and something could ignite it (i.e. a backfire that blows off the intake pipes, lol).

To be honest, I don't really understand the benefit of multi-port injection vs single point injection in a gaseous fuel scenario. It sort of makes sense with gasoline, but I imagine that with a gaseous fuel, the more time it has to mix evenly the better, no?

That leaves me with the final option, which is positioning the injectors where a traditional carburator would normally go, Throttle Body Injection style.

Any opinions?

[xtian999]

I saw a '91 lng civic gx on ebay for 6K. Done. Spend any leftover money on a track car that you can really mod and drive all out. Or buy a used racer that is already sorted.

Develop turbo induction system on junkyard motors. $50.00 each, if they pop, no biggie. When complete, install on Z06 vette and sell to Chevrolet.

Leave that poor old gm f-body alone. Just keep it clean and use good oil. Nothing you do to it will improve resale.

[mikernet]

I have no interest in a civic, or any FWD car for that matter.

The f-body is already gutted in and out and ready for some custom modding action. I don't intend on improving the resale, I intend on keeping the car for the very long forseeable future. The vehicle of choice is unfortunately non-negotiable - this has been my dream for many a year. The only other car I would even consider doing this build on is an 82 vette.

You would be surprised how potent you can make an f-body on the track with relative ease.

And lol @ sell to chevy...why would chevy have any interest in my turbo system? I'm not paving some sort of new path here. Lots of people have done (and actively do) turbos on LS engines.

I don't care if I win competitions with this car. I don't care if I win races with this car. I will do what I can to make it a fun and performant car to road race, but ultimately what I want is a cool and unique car build that I can drive daily. That car made my teenage years what they were, and this is my commemoration.

There is a lot more than just the engine going into this build. I'm working on a custom dash to house a large touchscreen that is hooked up to the car computer, which interfaces directly with the ECU for real-time monitoring, diagnostics, and tuning. The car computer controls virtually every aspect of the car - it controls the window motors, security system, door locks, etc. There are 4 cameras constantly recording to the hard drive. The suspension dampening and boost levels can be set from the touch screen. A second LCD is getting mounted in place of the speedo/tach/etc which shows RPM and speed.

I can keep going on and on...but this isn't your typical build. I've got countless hours of development time into the electronics so far, and I've got $60,000 budgeted for everything. The turbo propane motor is just rounding off the rest of the awesomeness in this car. It would be pretty lame to have all this cool stuff and a crappy motor.

[mikernet]

Slight change of plans...which I'm sure xtian will appreciate more, haha.

Tallied up some numbers and estimated hours of work...and...well, to get to where I want to get, I'd essentially be building a car from scratch, so I figured I might as well just build from scratch and start with a GTM Supercar frame.

So, I'm doing a much more mild refresh on the Trans Am which should be finished by the summer, so I'll have a kickass daily driver while I build the GTM. Putting in a new LS1 motor and T56 tranny, subframe connectors, partial rollcage, custom dash, carputer. Leaving out the custom ECU and saving that for the GTM.

So, I guess I'll come back to the propane madness in about 6 months time. I'll post a link to the Trans Am build thread on the thirdgen.org forums for those interested once I get that going.