I'm looking at ways to make the 2.5L make more horse power, at least 300, and still be somewhat reliable WITHOUT the use of a turbo,

I love N/A power. Is there a possible engine swap that could meet that? Besides the Camry V-6?.

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@Aeris, Hi if you can modify your engine to work on high octane gas, and with a new intake (to accommodate the new input) that may produce higher Horse Power. Not sure if out there is a kit sold just for that purpose. What it is known that are computer programs to simulate your ideas, even before you start building a new addition to an engine. Then, one can see the new parts modified in action, and find the new engine results. All the car companies are now doing that computer program simulation, and compete with each other even before building something. The gas car engine in digital era, have achieve his limitation (one must compromise - can get more power in exchange for something else).

 

Here is my take on what you should do. From experience.

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1.) Get custom .50+ Over 10:1 or higher compression pistons with High heat ceramic coated crowns, and Moly coated skirts, and heavy duty wrist pins.
2.) Have a machine shop hone your cylinders to fit the pistons: .50+ Over
3.) Have a machine shop port and polish your intake and exhaust ports
4.) Get an entire Ferrea valve-train, titanium retainers, etc.
5.) Get Molnar Technologies H-Beam Connecting Rods6.) Get the Nitrous Express Proton Series Nitrous System W/ 15Lb Bottle (35hp, 50hp, 75hp jetting included) also comes with the jetting chart.
7.) Get a Nitrous Express N2O Flow-Thru Nitrous Pressure Gauge (for the bottle)
8.) Get a Deatschwerks DW65c Fuel pump
9.) Get Deatschwerks 440cc - 550cc Fuel Injectors
10.) Get a Frankenstein Motorworks Header
11.) Get the Boomslang PnP Harness for the AEM EMS-4
12.) Get the AEM EMS-4
13.) Get the Agency Power Aluminum Crank Pulley
14.) Get a nice ACT Clutch
15.) Get a nice ACT Flywheel
16.) Find someone to tune the AEM EMS-4, and I can link the 300pg manual for the tuner.

The list could go on and on. I know the places for this engine.

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At least 300...I'm assuming you mean at the wheel. correct? The answer is, not easily. You'll notice in the build detailed above, which sounds suspiciously like the 2AR 'Frankenstein Motorworks' was doing (and I noticed the recommended header), you'll see it includes nitrous. Probably the ONLY cost-effective way you'll get 300 hp NA out of that engine without spending some serious money.

The 'Frankenstein' build, which was well-engineered and well thought out, was shooting for 240 as a goal and 300 as a 'stretch' goal but that was spinning to 9,000 rpm if needed. Unless you're willing to completely rebuild that motor, and he went with a 1AR crank to make it a 2.7L stroker, pistons, rods, valve springs, etc. and could do some of the basic machining himself, then 300 isn't a 'stretch' it's a dream.

How much are you looking to send on this motor and how much of the work can you do yourself? Budget and knowledge is going to dictate what's realistic...

 

I actually had no clue who that was until last week, just know the site. And this is my personal planned out build. Fortunately Papadakis Racing has been kind enough to help when I need to know specs and stock limitations of parts in this engine.

Btw If anyone ever needs specs and HP limits of factory parts, pm me.

 

1. Easiest way by far is turbo. Using 15psi will get you 300hp target.

2. Next easiest way is to find factory engine with 300hp and swap that in. Best to keep it in Toyota family. There are very few Toyota engines making +300hp.

3. Most extremely difficult by far, 5-10x more costly and time-consuming than #1 & 2 is to build NA engine from inside out. To get 300hp out of factory engine, you'll have to completely take apart engine and do Inbox9Five's list + more (his will only give you +15-75bhp depending upon size of nitrous shot). To get +150hp, you'll need:

- Bore and MID-sleeve block for
- larger high-compression pistons
- Offset-grind crank for longer stroke
- Custom forged rods
- Do all of inbox9Five's list (minus nitrous)
- Install aftermarket programmable EFI system like MoTeC, Electromotive TEC, LinkECU, Auslogic, AEM, Megasquirt, etc.
- 5-10 hrs Dyno-tuning after putting it all back together.

I used to have a shop down in Santa Barbara that did this kind of work and #3 can be done; cost you at least $15k.

 

No need to do this when you can just pickup a 1AR crank and I will agree that boost would make this whole effort so much easier.

 

Ah yes, forgot off-the-shelf stroker crank!

With modern high-efficiency turbos and electronic controls, turbo engine is no longer on/off monster that got Porsche 930 banned from U.S. in '70s. Nowadays, you can't even tell an engine is boosted. It starts building boost at low-RPMs, max-boost coincides with torque-peak, so it feels just like NA engine. Except with gobs more torque!!!

Here's modded Porsche 2.5l 4-cyl engine:


Can you tell it's boosted? At 2300rpms, it has more torque than factory engine does at its peak! And generates 4x factory power!!! Does 10-sec 1/4-mile runs @ 125mph+++

 

Im late to the party again here, I moved to a 100hp shot. I never sleeved the block. I'm doing a test with this engine. Stephan Papadakis told me not to sleeve it, as he doesn't with his 1000hp engine, with nitrous and turbo. So no, you do not need to sleeve this block. This block has problems with sleeves dropping (Per Stephan's advice). Sure to sleeve a block is nice, but these are incredibly strong blocks. If you manage to sleeve one without them dropping, i suggest you contact Stephan. I'm sure if his team hasn't figured it out just yet, they would like to know... I know i would lol. Apparently to correctly sleeve them you would have to leave a nice little ledge at the bottom to keep them from dropping, but then that wouldn't be a full sleeve either. Just my 2 cents.

 

Which nitrous system did you get? I had a NOS system on my Supra way back when.

Build parameters depends on what you're doing with engine. Papadakis tears down and rebuilds his engine after every 4-days of use. So if you want to do that as well, that's kind of build you'll go with.

Sleeves have been done for over 100-years, so they're no secret, Rolls Royce sleeves use to be hot item, now many other vendors provide flanged sleeves to make it extremely easy. Many early alloy engines used flanged steel sleeves and can be replaced easily if you've got a tuning mishap and blow headgasket and scratch up your bores. I usually install with sleeve about 0.05mm taller than deck so there's extra clamping pressure. I'm sure Papadakis can figure out why factory cars don't drop their sleeves while his does.


Autohaus - MB sylinder sleeve

Extra displacement is easiest and cheapest way for more power. I've taken 2.5l out to 3.3l with max overbore +8mm and stroker crank on Porsche engines. Often done on many open-deck Honda engines too. To get those large pistons in you remove original cylinders completely and replace with wet-sleeves.


Extremely tough build that last for decades on daily-driver or trackday car and doesn't require rebuilding every 4 events. Here's Papadakis's con-rod bearings after 4-events:


Porsche figured out how to fix this problem decades ago, so I'm sure he can learn to do it too.

It's easy to get high-HP, much tougher to make that engine last. I worked on a 1600-bhp 4-cylinder 20-yrs ago. Originally built by Norwood for a Porsche 968. Customer requirement was that it would last an entire season of racing. It actually went for 2 seasons before needing rebuild.