Maximum theoretical output

Splinter · Post by **Splinter** » Sun Mar 12, 2006 5:10 am

Anyone know how to determine what the maximum theoretical output of a 2.5L engine would be, assuming it was limited to 9000rpm and running on gasoline?

wiscon_mark · Post by **wiscon_mark** » Sun Mar 12, 2006 5:30 am

uh, forced induction or not? race gas or pump gas? Running accessories for normal cars, or all power to the crank?

Just clearing this stuff up before the real car people get here

entirelyturbo · Post by **entirelyturbo** » Sun Mar 12, 2006 1:55 pm

What 2.5L engine?

BAC5.2 · Post by **BAC5.2** » Sun Mar 12, 2006 5:28 pm

How much boost? Head flow? Specs?

I know 750whp can be done on a 2.5.

Splinter · Post by **Splinter** » Sun Mar 12, 2006 9:01 pm

I would think there would be a way to do it based on the properties of the gasoline and air reaction. Just on displacement, and the chemical expansion and such

Am I wrong?

entirelyturbo · Post by **entirelyturbo** » Sun Mar 12, 2006 10:28 pm

Well, the capabilities of the engine have a lot to do with it. I think we all can agree that an EJ22T can ultimately create more power reliably than a Phase I EJ25, because the EJ22T is an overall better-built engine. Assume proper tuning was utilized in both cases.

Splinter · Post by **Splinter** » Sun Mar 12, 2006 10:52 pm

Just talking about the theoretical max for any engine based on displacement alone.

Someone is trying to convince me that their friend has a 900hp 1.8L engine that runs on pump gas, and I just dont think it's possible

wiscon_mark · Post by **wiscon_mark** » Sun Mar 12, 2006 10:59 pm

pump gas?

no f'n way. What would be the redline? 14,000 rpms?

206er · Post by **206er** » Sun Mar 12, 2006 11:01 pm

I think even to calculate the maz capability of an engine you would need to include volumetric efficiency or head flow values. as far as the total energy available from 2.5L of whatever A/F ratio, I forget that calculation.

evolutionmovement · Post by **evolutionmovement** » Mon Mar 13, 2006 12:23 am

Is he trying to say without a turbo? Last year's F1 engines were around there with 3.0 V10s running near 20,000 rpm. At least when he lies, he does it big.

Splinter · Post by **Splinter** » Mon Mar 13, 2006 12:24 am

There was definitely some kind of forced induction, dunno if it was turbo or super.

Maybe even nitrous, but I doubt even that could put out those kind of numbers.

entirelyturbo · Post by **entirelyturbo** » Mon Mar 13, 2006 1:40 am

Pump gas? No way. But if your friend has access to race gas and a several million-dollar budget, then sure it's possible.

Lest we forget, BMW used to run a 1.5 liter 4cyl turbocharged in their F1 cars up until the mid 80's, that made up to 1000hp (that's right, one thousand) at one point. The engine was expected to last a whole 2-hour F1 race. Some of that technology went into the 2002 Turbo, one of the reasons why that car is so highly sought after.

evolutionmovement · Post by **evolutionmovement** » Mon Mar 13, 2006 2:33 am

Those engines ran up to 1300 hp for qualifying. It was the same block as the 2002. They actually used to take used blocks from the junk yard to build the race engines as they were better than new blocks, though I can't recall if it was a design change or being broken in that made the difference. In race trim they'd be more around 900 HP. Pretty f'n cool.

free5ty1e · Post by **free5ty1e** » Mon Mar 13, 2006 3:17 pm

I say damn. [drool] Just think if that kind of power were distributed between four wheels instead of just two. [/drool]

BAC5.2 · Post by **BAC5.2** » Mon Mar 13, 2006 4:31 pm

It's a nearly impossible question. You can defend against det pretty well with race gas, and you can make a lot of power with nitrous and boost.

For pump gas, I know at LEAST 455whp is possible.

entirelyturbo · Post by **entirelyturbo** » Mon Mar 13, 2006 6:11 pm

evolutionmovement wrote:Those engines ran up to 1300 hp for qualifying. It was the same block as the 2002. They actually used to take used blocks from the junk yard to build the race engines as they were better than new blocks, though I can't recall if it was a design change or being broken in that made the difference. In race trim they'd be more around 900 HP. Pretty f'n cool.

Steve, would you know what they did to those engines to make them so powerful? As in, what were the bottom ends/block/heads made of, how much boost they ran, etc. etc.? It has to be something ridiculous... All I know are that they were 1.5L 4cyl's with 1000hp

evolutionmovement · Post by **evolutionmovement** » Mon Mar 13, 2006 6:39 pm

Actually, my source claims 1400 top HP. They used to get older blocks because of the stress relief. They had very strong bottom end design and cast-iron block. There's no mention of component changes in race trim, but the original production crank was forged. Compression was 6.7:1. This is an engine who's design started in the late fifties.

BAC5.2 · Post by **BAC5.2** » Mon Mar 13, 2006 7:22 pm

Back in the day, twin charging was a big thing. Make boost to the point where it was ridiculous. That's your 600bhp from under 2 liters right there.

I think the basic theoretical limit comes to around 15bhp per cubic inch. So from 2.5L you get around 1500bhp.

I'm sure that number could be raised or lowered slightly, depending on the desired duration of the power.

entirelyturbo · Post by **entirelyturbo** » Tue Mar 14, 2006 4:36 am

evolutionmovement wrote:Actually, my source claims 1400 top HP. They used to get older blocks because of the stress relief. They had very strong bottom end design and cast-iron block. There's no mention of component changes in race trim, but the original production crank was forged. Compression was 6.7:1. This is an engine who's design started in the late fifties.

Awesome.

I'd be willing to bet that they did as much to make the engine more efficient so it could be more powerful, instead of just throwing a bazillion lbs of boost at it.

An average NA internal-combustion engine utilizes something like 20-25% of the potential energy in the explosion in the cylinder. Turbocharged engines increase that to around 40%, maybe up to 50% in some cases. They probably found a way (maybe by balancing the engine as precisely as humanly possible, for example) to get that efficiency figure to go up even higher.

I want to say that some guys racing a Vette C5-R in sports car racing a few years ago got a whole 100hp out of the engine by doing nothing more than lightening and balancing the crankshaft as best they could.

There comes a point where one must start considering efficiency in search of more power, because you can only fit so much fuel and air into an engine at one time.

wiscon_mark · Post by **wiscon_mark** » Tue Mar 14, 2006 4:57 am

haha, so true. I'd rather have a mod that gave me the opportunity to make it give me more performance, or better gas mileage (efficiency FTW).

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Maximum theoretical output

Maximum theoretical output