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Hello, everyone!

I have here a rather interesting engine that I have spent the last 12 hours straight working on. The engine started as an L61 platform, but I poked, prodded, and beat it to death with experimenting.

The result is what I call Project Firefly.



I'm not going to lie. The combination of specs I have in that screenshot took a balancing act the circus would be proud of.

The primary focus of this engine is powerful revs at low RPM. The triumph that I found in the final result is how close on the RPM band the Torque and Horsepower are. It means that this engine has a rather nice little pocket of power at a range of RPMs that isn't insanely high. While yes, the engine could be much, much more powerful, the current balance is rather nice. It cranks out a very pretty 5.0s 0-60 in a 2300 lb car (based on the transmission), while getting next to 30 mpg. And truth be told, it's not all that expensive (comparatively) to produce.

Anyone more experienced at this have any thoughts or suggestions that might make it better? I plan on setting up a 6-cylinder with a similar "within 1000 RPM" concept to add to the lineup.

I would say the engine -is- expensive. Have quality sliders been used? They are the main cause of high costs.

Where would this engine be aimed, in a fuel efficient car? All rounder?

As for fuel economy, that depends on the gearing, but at 15%, for an economy engine, it is quite low. I think it should be possible to build an engine that costs half as much, with double the efficiency and power andhave 1/3 servicing costs. I Haven't tried the new release yet since my notebook is away being repaired, but it may no longer be possible with the new changes...

The new build nerfs economy and turbo quite a bit, so these figures are quite reasonable for b1417. Given it's about twice as many man hours to produce than what I'd typically see in a mass produced car, and the turbo profile, I thought it might be suited to say a higher performance hot hatch. What I'd really like to see in the Clio, maybe?

If it fits into the smaller modern mid engine, I'd say this would be competitive as a opel speeder/ vx220 style sports car.

The turbo looks like it could be optimized much better, given that it only makes peak boost over a narrow rpm range. I'll give it a shot when I get home from work.

I'll do the same here, this engine isn't balanced at all. When I get home, I'll do an engine and post the file for you to have a look.

This is a early prototype, so I expect it to have flaws. Thanks to everyone for their input, I'll be tweaking the quality a little. I have them all set to 10, mostly to pull a few extra horses out.

The primary goal of this engine is the same as Drash Motorworks, Ltd: Performance for a reasonable price. Right now, I feel like I've hit my goal in that I have a good, powerful engine that can be used in a variety of platforms. It's a good starting point, but my target competitor was the GM Ecotec LNF line, which anyone could buy a crate engine at retail for around $3000. (Which means nialloftara hit the nail on the head) But again, the qualities are all set fairly high, so I have some play room that won't affect the stats too much.

For the turbo, I am aware that the peak range is narrow. I specifically planned for that. If I optimized the turbo any further, it distorted the ultimate goal of this engine, which was having the Torque and Horsepower peak closely together, so that when applied to either a sports car or a sedan, they both feel like a sports car without sacrificing major investments. In my experimenting, I was able to get the horsepower up and over 350, but the torque fell off the charts and the RPM peak was almost 7000.

Having max torque and power together is honestly useless. Torque is, I like to think, the rate with which the power increases. Therefore, in your engine you have the highest rate of acceleration at the top of the rev range, and not much in the rest.

I suggest you look at kill robs post explaining the difference between power and torque.

If you spool the turbos up earlier you'll have better economy, responsiveness and overall performance.

What he said. A well designed street engine will have the torque peak as low as possible and the horsepower peak as high as possible, giving the driver a wide powerband. Some high strung race engines may have the two peaks close together, but that's more like an unwanted side effect rather than an ideal design goal.

That's exactly the information I've been looking for. I understand the concept of torque versus horsepower, I just assumed having both together was a good thing, because that's how my cavalier is set up. It puts out about 280 to the wheels at around 5500 if I had to guess, and the torque feels like it follows the entire way. I can't say for sure because I've only had it dyno'd once and I have no idea what I did with the printout.

I'll get back to the drawing board and see what I can come up with. I'll see you all soon.

Sorry for the double post. I made some slight adjustments and poked and prodded a few minor tweaks. This is the Firefly, revision 1:



Settings are as thus:

Inline-4, Aluminum block.
Bore: 3.433"
Stroke: 3.740"
Crankshaft: Forged Steel
Rods: I-Beam Steel
Pistons: Lightweight Forged
Dual Overhead Cam, 4 valves; Aluminum Heads
11.8:1 Compression
Cam Profile is set to 50
VVT on all Cams
No VVL
Single Ball Bearing Turbo, Medium-sized Intercooler.
Compressor is 2.047"
Turbine is 2.087"
AR Ratio is 0.75:1
Max Boost is set to 15.43 PSI
Single Point Direct Injection
Racing Intake
Super Unleaded Fuel (93.1 Octane)
11.1:1 Fuel Mix
Ignition Timing set to 60
RPM Limit set to 6800
High-Flow Catalytic Converter
2.5" Exhaust with single Reverse-Flow muffler, no bypass

I greatly appreciate the input everyone has given. I'm an enthusiast, far from being a mechanic; but I'm slowly learning.

Major improvement. I'd suggest using an air filter on a road car to keep the service costs reasonable. Also, a bigger exhaust would free up some more power. Turbos love big exhaust.

Good call on that one. Hadn't even considered that.

Changed it to a 2.75" exhaust, standard intake, and 49 cam profile.

HP is still 300 @ 6400, but Torque fell to 309 ft-lbs @ 3600

Service costs are now $2194.41 and Material Cost dropped by $40

Big thing is that Reliability went up by 20.

I did a little experimentation with other engine layouts using this base.

Moved it up to 6-inline, got this result with no modification:


Dropped the bore by .030" and pulled the AR ratio up to 1.03:1


Dropped the bore by another 0.010" and set the AR to 0.85:1, gave it a couple extra cylinders:


Looks like scalability is possible on this platform. Again, I greatly appreciate everyone's help with this.

Not too shabby, sir. I cobbled together an example of what I personally look for in an engine, based loosely on your four cylinder. Zero quality settings (cheap!), full boost from 2800 to 7500 rpm, respectable fuel economy (21.65%), and yes, it fits transversely in all mid engine cars (barely).