What's the secret

…Of high boost engines that dont guzzle fuel like crazy?

I have a 2.5 iron ohv v8 I’d like to give it a pair of turbos and make it legal for the ringmaster league…

how should I tune the turbos?

depends on what you mean high boost?

you can’t really make an highpower eco-engine

[quote=“xABSOLUTIONx”]depends on what you mean high boost?

you can’t really make an highpower eco-engine[/quote]

someone made a 700+ hp 3.8 inline 6 with 20% economy

That would be dragawn. The trick to that engine was to use super cheap direct injection (quality slider to -9 or so). After that its not too hard to get 700hp and economy >20%.

That’s for an i6 though. You may have trouble keeping costs down and efficiency up to make it worth putting turbo on a v8 because the costs jump significantly from both the block and turbo ends. However using a big-ass v8 NA block yields up to 960hp :stuck_out_tongue:

[quote=“strop”]That would be dragawn. The trick to that engine was to use super cheap direct injection (quality slider to -9 or so). After that its not too hard to get 700hp and economy >20%.

That’s for an i6 though. You may have trouble keeping costs down and efficiency up to make it worth putting turbo on a v8 because the costs jump significantly from both the block and turbo ends. However using a big-ass v8 NA block yields up to 960hp :stuck_out_tongue:[/quote]

Yet another reason for wanting blowers to be available… they may have a parasitic effect but sure dont blow away your budget

What you have to do is retard (For some reason the site keeps swapping the D in Retard to a T, oh you silly website you.) your ignition timing (I use about 30 or so) so that you can run low fuel mixtures while retaining high compression and boost.

This may result in slightly less high-end power, but you can then configure your engine to excel in the low-RPM area of use.

In example I have a turbocharged 6.6(I think, I can’t remember exact displacement, but I know it was 6+ liter) OHV V8 built in 2014. That manages to get 20%+ Efficiency and produce 600-ish horsepower and 1000+ Nm of torque. Does so all before 5000RPM and still manages to get 50,000 Km or so MTBF. The trick is to keep your boost all in the lower RPM range, I tend to use the largest Turbo I can fit but then fine-tune the AR ratio and Compressor for the best results.

I just pulled out of my sleeve a 620 hp 4.78 I6 pushrod that is a low revver it runs below 6k rpm it also has slightly morfe than 20% economy and mtbf of 60km all in less than 100 MHrs and 1500 material cost

Sigh I don’t want to give my secrets away before the endurance challenge starts, but I’ll give you guys a small insight.

I managed to get a competitive Turbocharged engine for GT2, which complies to the restriction of 30+% economy.
There seems to be a misconception here: Good ol’ OHV and pushrod designs may be cheap and reliable, but they have suckish efficiëncy, not only resulting in a general power drop, but also resulting in higher fuel consumption.

Since this game calculates realistic fuel consumption in pretty low revs, it is beneficial to economy to have your high torque as low as possible, so your turbo should pick up as soon as possible. A high AR ratio turbo setup may help pick the turbo to pick up earlier, but, probably due to a less efficient turbine, the engine becomes less efficiënt too at the same time. So if you only consider good economy you’d indeed want a low AR turbo setup, but sadly in even slightly high revs the turbo simply won’t be able to provide the engine with enough boost power anymore. This is why I’ve experimented way before with turbo/NA hybrids with the turbo only acting in low revs, but it simply isn’t worth the extra weight/price tag. So in general it’s a balancing act, but the golden rule to economy is some good power down low.

Edit: With AR efficiency I meant high AR is efficient in high revs and low AR is efficient in low revs.

No. The game calculates efficiency/economy in the engine designer between 1500 and 2500 RPM, because that’s the usual RPM band where normal engines are driven.

When it comes to realistic fuel consumption in the car designer, the RPM don’t really matter (directly). The “driver” uses the gear with the lowest effective fuel consumption at various speeds considering BSFC and additional losses becauses of sucking against a partially closed throttle.

For example: Let’s say you need 10 kW for cruising at 100 km/h and the driver can decide between only two gears (just a simplification for this example). In the first gear, the engine runs at 6000 RPM and makes exactly 10 kW at full throttle. This means it gets no penalty on the BSFC, let’s say it is 300 g/kWh. The fuel consumption then is 10 kW * 300 g/kWh -> 3000 g/h. In the second gear, it makes 30 kW at 3000 RPM, but has a BSFC of 200 g/kWh at full throttle. You only need 10 kW, so you have to close the throttle. The BSFC will thus get worse, let’s say 350 g/kWh. The fuel consumption then is 10 kW * 350 g/kWh -> 3500 g/h. So the driver will choose the first gear and run at 6000 RPM.

This is uncommon in real life, yes, but not impossible. Especially small, high revving engines really can behave that way. The problem of normal size or big engines with aggressive cam profiles is, that they make way too much power in their most efficient RPM range. When cruising in that RPM range, they suffer from heavy throttle losses and are thus still more efficient at lower RPM, where they make not much power but have smaller throttle losses.

Well yeah, that’s what I meant with “realistic”, I just didn’t know exactly at what rpm’s

good enough? :laughing: