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Discussion Starter · #1 · (Edited)
I have a question about the maximum ammount of hp I can get from my naturally aspirated engine.

I understand intake/headers/exhuast will improve hp.

I understand my car on paper at the flywheel has 173hp.
I understand drive train loss.

Lets say for example I now have 153 hp at the wheels.
Lets say a cat-back exhaust will give +10 hp.
Lets say an air intake will give +10hp.

Lets say I now have 173hp at the wheels.

Correct me if im wrong but does this mean I have maxed out my engine? Is there any way I can create more hp than what I would currently have without turbo/super? What I mean is - is it possible to create more HP from bolt on mods than what is created by the engine. I understand making the engine more efficent produces more HP at the wheels but does this ever gain more than what my engine is capable of pushing out?

Thanks.
 

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Next best thing after I/H/E is a tune but you'll be running on premium gas!!!
Be cautious with HP number..... if an upgrade grant you 15HP but stole you 20 torque you have to ask yourself if it's worthted!!! HP number sells car, torque number win races!!!
Just my 2 pennys
 

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Discussion Starter · #3 · (Edited)
Okay so maybe I'm asking the question the wrong way.

What I'm trying to ask is - is it possible to have more than 173hp at the wheels without supercharge/turbocharge.


Naturally Aspirated bolt on, without modifying the engine interals (keeping everything inside my engine factory - valves, cams, pistons etc)
 

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for bolt on maybe a header rather then are stock manfold exgaust..
could gain you a few hp..
maybe port&polish the head.. if its not been done already? Idk never had this one a part mayeb Crock knows since he pulled his motor apart?

Since you don't want too change the stock motor I can't see you getting too much more hp out of it.

(guess you'll need to just work on getting more out of the hp already there)
ie, reflash computer.. etc..
 

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To answer your original question -- yes, the engine is possibly capable of producing more power than the original factory spec.

The 173HP rating is the total amount of power the ENGINE is capable of producing, most likely measured on an engine dyno, as it's configured/built from the factory. Of course if you start to modify the engine, that number is going to change, and not just up but possibly down as well. And of course engine power output is only one aspect of the car's overall performance.

NA tuning is a very broad topic, and simple things like intake, header and exhaust are relatively easy and inexpensive, but will only get you so far. Increasing displacement, changing to lighter components, increasing air and fuel flow, and ECU reprogramming are some more advanced techniques.
 

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I think you have some good questions about HP. The only way to truly know is to dyno test before and after. If going by manufacture claims of HP gains on a product it is up in the air. Using your example of a CAI and a cat back exhaust would you gain a full 20 HP? Assume the manufacturers claim is true the question then is would it be additive considering multiple products?

Look at a typical power curve for HP and torque then see where you normally drive and you won't be using the full available HP anyway. This is my opinion and I am not a mechanic.
 

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2021 Forte GT w/GT2, Currant Red, SXTH Element Intercooler Kit, Evilla Exhaust, Takeda S2 Intake
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The only way to increase horsepower significantly -- without going forced induction -- is by increasing the compression ratio. The benefit to increased compression is that it increases HP throughout the RPM range. Our engines are supposed to be 10.5:1 -- if you were to increase that to 11:1 or 12:1 you could hit the magic 200 HP...BUT...you would need to tune for it and run a higher octane fuel. That is how the SI makes 197 HP with a 2.0L engine -- very high compression.
 

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The only way to increase horsepower significantly -- without going forced induction -- is by increasing the compression ratio. The benefit to increased compression is that it increases HP throughout the RPM range. Our engines are supposed to be 10.5:1 -- if you were to increase that to 11:1 or 12:1 you could hit the magic 200 HP...BUT...you would need to tune for it and run a higher octane fuel. That is how the SI makes 197 HP with a 2.0L engine -- very high compression.
What kind of shop would do such a thing? And what is the approx cost of one of those?
 

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What kind of shop would do such a thing? And what is the approx cost of one of those?
Engine machine shop or speed shop can do this. You would either need to replace the pistons with performance ones (if any are made for this engine -- haven't checked myself) or shave the cylinder head and possibly deck the block. Basically you have to reduce the size of the combustion chamber to increase the cylinder compression. You also have to look at the valve-to-piston clearance when you do these mods -- might have to notch the pistons to clear the valves.

If pistons are available it would cost the price of the pistons and probably close to $1000...if you are unable to do the work yourself.
 

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I have a question about the maximum ammount of hp I can get from my naturally aspirated engine.

I understand intake/headers/exhuast will improve hp.

I understand my car on paper at the flywheel has 173hp.
I understand drive train loss.

Lets say for example I now have 153 hp at the wheels.
Lets say a cat-back exhaust will give +10 hp.
Lets say an air intake will give +10hp.

Lets say I now have 173hp at the wheels.

Correct me if im wrong but does this mean I have maxed out my engine? Is there any way I can create more hp than what I would currently have without turbo/super? What I mean is - is it possible to create more HP from bolt on mods than what is created by the engine. I understand making the engine more efficent produces more HP at the wheels but does this ever gain more than what my engine is capable of pushing out?

Thanks.
The intake prolly wont get you 10hp to the wheel
Turbokits says our headers are not worth replacing. So far.
 

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stock internals? it is possible to make more than 173 whp, but if you were to do an all motor build you could get as much as the 240 your 2.4 would get at 100% efficiency
much higher comp (these engines could stand up to it, there are people running 22, 23 psi in gen coupes right now with no problems), have the cylinders bored out and sleeved to maintain same displacement but make it stronger, higher duration cams, TUNE, good tires, i/h/e, valves and springs (possibly sold with the cams), injectors, fuel pump, better cooling radiator, no p/s or the electric p/s from ex eco package, just bare bones because you want to increase your power to weight ratio, not just power.
 

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Discussion Starter · #13 ·
Thanks for the info everyone.

I understand intake and exhuast will not get me the full 173hp at the wheels - it was just an example.

So from what I understand I can make more than factory spec HP without forced air. However I will need to change engine internals, which I think is fine but would ultimately change the engine itself.

Is it possible to make 173+ hp with strictly intake and exhaust and piggyback ecu (without/without flash - leaving everything else factory).

Can I make more than 173 without touching my actual engine (internals) and aside from ECU (even if its a full flash) + I,H,E what else is there that does not involve getting into the engine itself.
 

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Thanks for the info everyone.

I understand intake and exhuast will not get me the full 173hp at the wheels - it was just an example.

So from what I understand I can make more than factory spec HP without forced air. However I will need to change engine internals, which I think is fine but would ultimately change the engine itself.

Is it possible to make 173+ hp with strictly intake and exhaust and piggyback ecu (without/without flash - leaving everything else factory).

Can I make more than 173 without touching my actual engine (internals) and aside from ECU (even if its a full flash) + I,H,E what else is there that does not involve getting into the engine itself.
IF, and this is a big IF, Kia honestly rated the engine based on an SAE dynomometer test of the engine with everything hooked up (factory exhaust, factory intake, and all accessories -- alternator, water pump, serp belt, etc) then it is feasible to free-up HP by using an aftermarket (A/F) cat-back exhaust and intake. If the base line at the wheels is 153 HP then I'd be willing to bet you may get 8-12 more WHP with a good intake and exhaust set up. IF the engine's HP rating was based on an engine with open exhaust and no restriction intake the answer would be no, you can't get anywhere near 173 HP with A/F parts.
 

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If you just want to get 173hp to the wheels. Do all your bolt on, I, H, E, crank pulley, (hyper ground system, and Hyper Voltage stabilizer by Sun Automobile.) Change your oil to AmsOil Synthetic and get your ecu tuned if possible. That should get you close to your 173 whp. If not, you will definitely feel a difference. ;-)
 

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I have a question about the maximum ammount of hp I can get from my naturally aspirated engine.

I understand intake/headers/exhuast will improve hp.

I understand my car on paper at the flywheel has 173hp.
I understand drive train loss.

Lets say for example I now have 153 hp at the wheels.
Lets say a cat-back exhaust will give +10 hp.
Lets say an air intake will give +10hp.

Lets say I now have 173hp at the wheels.

Correct me if im wrong but does this mean I have maxed out my engine? Is there any way I can create more hp than what I would currently have without turbo/super? What I mean is - is it possible to create more HP from bolt on mods than what is created by the engine. I understand making the engine more efficent produces more HP at the wheels but does this ever gain more than what my engine is capable of pushing out?

Thanks.
It doesn't really work like that.

Mods just don't add up on top of each other, they work together.

Also, it is possible to gain power and get over the flywheel rating N/A, but you'll have to spend some money (cams, valves and springs, port/polish, etc).
 

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Mods just don't add up on top of each other, they work together.
This I agree with. Setting an arbitrary number for what a mod should add is a guess at best. With this in mind, the factory header seems to be pretty efficient already, so upgrading your exhaust from front to rear would likely cost you $1,000 plus, and maybe net you 15-20hp tops. Probably more like 10-12hp.

A CAI might pick you up a couple of horsepower, but seriously not more than 5 tops.

If you are looking at competing with n/a power, then your ideas of exhaust and intake are definitely good. They will net you the best results for the money without going to forced induction or nitrous. Beyond that, concentrate on weight reduction - it will seriously make an enormous difference.

If you want to make serious power N/A then you are going to have to pull the engine out and rebuild it with some serious parts. Higher compression pistons, cams, port & polish, and still cannot expect to get huge gains. Maybe 45-50hp tops, and it will cost you at least as much as a turbo upgrade.

To sum up - No, there is no cheap and easy alternative to making big power gains without voiding your warranty. lol.
 
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