Efini Dura Engine Series

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Efini DuraCompact Series

'04 1.6T Engine Design, made for low-weight Front and Mid-engine applications, 3 Variants currently

-1.6T Eco Designed with fuel economy and horsepower in mind

-1.6T Corse Designed with horsepower in mind, while keeping fuel economy fairly good

-1.6T Race Designed with horsepower in mind, without having an engine that costs too much or consumes way too much

Efini DuraVeloce Series

'04 2.0L N/A and Turbo Motors, coming in 5 variants, ranging from low-cost units to high-mpg units or high-performance units

-2.0 Eco Designed with cost in mind, while keeping fuel efficiency fairly high

-2.0T Eco Designed as a great combination of fuel efficiency and performance

-2.0T Sportivo Designed as a performance-oriented variant of the 2.0T Eco while still running on regular

-2.0T Corse Designed as an even more performance-oriented variant of the 2.0T Eco running on premium

-2.0T Race Designed as a racing engine that is reliable, cheap and economical enough to be able to be afforded by the masses

Efini DuraSei Series

'04 Series of 6cylinder motors for higher power applications

-3.0T Eco Designed as an affordable, powerful and smooth motor for grand tourers/sports cars, able to be run on regular 91 octane petrol

Efini OttoCompact Series

'04 Series of 8cylinder motors derived from the DuraCompact Lineup

-3.2T Eco Designed as a low-consumption, eco-friendy motor, yet powerful and smooth. It’s two 1.6T Ecos together. Proves V8s really are two I4s joined together.

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Added new quirky small-displacement turbo dohc v8! tell me what you think about it!

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you DO know. when you put “DURA” in the name, you’re gonna market it for being reliable right?
and your ‘normal’ engine having only 20% more reliability than your ‘race’ engine isn’t exactly durable.

also, the turbo is really choked by the intercooler, a lot.

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Almost all of these engines are self-destructing and are poorly engineered in general. The components in the right hand diagram should be all green with the exception of the turbo.

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To be honest, a good friend of mine told me reliability should be at least 40, and I sort of misinterpreted that and just made my engines as high revving as possible while staying at the 40 mark.

I’m guessing either reducing the rpm or changing some components like the crankshaft would fix these tiny problems.

As for the racing engine, well it’s not totally a racing engine of course, I wanted to keep it a little sane, I could’ve made it far more powerful sacrificing reliability, fuel economy and cost even further, but I decided not to, so that it could make sense installing it in a mass-bought car

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As I’ve also told to koolkei, I thought reliability should be kept around 40, and a problem that is fixable with reducing the max. rpm and/or upgrading some bottom-end parts isn’t called bad engineering. I was initially designing my motors with at least 60 reliability in mind, but I misenterpreted what a friend said and simply increased max rpm to increase performance index until i reached 40 reliability.

No need to be so harsh on my first work in automation, and once again these problems are easily fixable, I’ll fix the motors and green’em out whenever I have enough spare time, it really is easy cause almost all of them start getting yellow and orange past the max horsepower mark, before that they’re all green.

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I try to stick around 70 reliability for all normal and sport engines, 60 for pretty hefty racey engines, and 50 for all out race engines. Only time i dont stay at those limits is for competitions that dont need/score reliability aswell as other engine aspects. Or if the engines are in earlier years as well.

I dont know why people in this thread and others are so harsh to people when engines/cars are put up that are not up to their standards.

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Thanks for understanding.

In fact, I opened up automation to try my idea out, I replaced the bottom end parts with stronger ones to green the engine out, I took the 3.2t v8 and slapped stronger parts on, car ended costing just $130, more and without almost not sacrificing car desirability at all (Efini Ottocilindre, scores 150+ competitiveness on three categories with a 30% on top of the base price) it went from 40 reliability to 65. Sure, there’s a bit more work to be done to make it more reliable, and someone could’ve come up with a better design than me, that’s for sure, this v8 was more done as an experiment to join two I4s, I can tweak all of the motors with little expense and bring’em up to higher reliability standards.

So… thanks for reading this and reading my posts, I’ll leave a reply to bump the thread when the fixes are done

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Sorry, I wasn’t trying to be harsh, I should have probably worded it differently. I think in regards to rpm vs reliability you might want to consider revising your bore/stroke ratio instead. Your engines dont seem to be suffering from much valve float, so a larger bore and shorter stroke could be an easy fix. Cheers.

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I will share my 2 cents on designing engines :stuck_out_tongue:

If you want an engine with a wide powerband and a good grunt, you won’t need a high reving engine, meaning you can use an undersquare design, which will improve the reliability drastically. Also, with low reving engines, a 2 valves per cylinder set-up works nicely, because peak power is usually at lower rpms. That can be done with 4 valves for sure, but a 2 valve system is lighter and less expensive.

On the other hand, a high reving engine will need and oversquare design with a DOHC system, but if is not tune properly you will end with the peak power high in the revs, meaning that you will need to use high quality parts to preserve reliability.

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well, if my words were harsh, i’m sorry, because i didn’t mean it, and i didn’t felt like i was typing something harsh.

but now that i know that’s your first build… that is actually not bad… rather good for a first build.

anyway, here’s some constructive critic from me:

  • reliability target can’t be a fixed number. 40 reliability engine in the 1950s is GREAT
    but 65 reliability engine in the 1990s are average. and high70-low80s reliability engine in the 10s are above average. simply, it ranges between the years. so what your friend said, keep it around 40 reliability, in what year?

  • an optimal engine have quite a bit of leftover revs after the peak power. i mean like extra 300-800rpm depending on the engine config. so i suggest get the cam profile lower and re-tune the turbo. lower peak power? sure. but it gets you more efficiency, and usually, a wider power band. and sometimes, even when designing a race car, a slightly wider power band could sometimes be faster than slightly higher peak power

  • when designing an engine from scratch, you need to know the goal you want to achieve. is it a race engine? and eco engine? a super durable engine? a truck engine?
    this defines what you can do to the engine later on.

  • race/performance engine? do an engine with bore>stroke, because you can give it more revs without sacrificing much reliability, which means higher specific output (hp/liter)

  • eco engine? stroke > bore, because you don’t care about revs and peak power. it’s all about the overall powerband. highest performance index with the least peak power. and because longer stroke engine has a better torque band for the same capacity. and, it’s lighter than an undersquared engine of the same capacity. these are usually low revving engines.

  • durable and truck engines? bore=stroke or just similiar bore to stroke size. because the longer stroke will give better power, but we need the shorter stroke because it could rev slightly higher without much reliability impact. a compromise on both type of engines.

of course, there are limitation and exception when you’re only modifiying and only making a new variant of an already existing engine family.

also, do you know how to export your engine? and how to attach files here? put it up so some of us could get a closer look :slight_smile:

for the others, cmiiw.

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I will actually go straight out and admit I’m
The friend, I really didn’t give a year, I was going off of something TurboJ said in his miniseries of engine optimization where in 1980 he said “35 reliability is good enough since you’ll never rev this high anyways” I guess I’m just really really bad at giving out advice :stuck_out_tongue: in fact, don’t ask me for any, you’re better off going at it.

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oh yeah forgot to say, turbo does effect the reliability quite badly if you didn’t use it correctly.

but even in 1980s, 35 reliability? there’s just no excuse for that. saying “you never rev that high anyway” is rather pretty ignorant. since you don’t know how people drive, and neither do i, but i do know i hit the limiter on the things i ride relatively often.

except that is, you’re building a race engine. then 35 reliability is rightly justified.

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I just built a turbo engine for KHT in 1985 with 51 reliability, 6500 rpm redline 342 hp i think for reference.

Id also be willing to help you out with some engines, send me a pm and we can collaborate if you want.

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I’d have to thank all of you for the helpful advice, I’ll give designing another engine a shot, this time following the advice. I’ll post results, I may upload the engine export as well.

I can get 65 reliability out of all of my normal previous engine designs easily, is 65 okay or should I look for 70+??

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Depends on the year

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I always use 2004

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Thats good for 2004

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Okay, then im going to upgrade bottom-end parts on most of the designs

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oh yeah now to the more advanced part. cost.
forged part are usually okay. they’re more expensive but are justifiable by the benefits they give.

but billet crank, titanium rods, and lightweight pistons are MUCH harder to justify because they’re almost or even more than twice more expensive, and usually not as good of an upgrade. sometimes, it’s better to take a hit in reliability and stay with forged parts, but other times, where cost is not as much of a concern. go for it :slight_smile:

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