DavidNJ

First, I work with an engine builder...I don't build them myself. But I do get into the details. It seems that Wadzii is an engine builder familiar with this engine so his participation in this thread is good.

While angularity is important, I've never heard of a racing engine that didn't use every amount of displacement it could get. When there are different ways to get there the builder goes for a wider bore rather than a longer stroke. For example, many 355 Chevys (355 is a .030 over 350) use a 400 block to use a 4.155 bore and 3.25 stroke vs. 4.03 and 3.48. But if the rule says 355 and 12:1 compression the engines are 355 and 12:1, not 350 or 11.5:1.

The rod length difference is less than a 5.7" rod vs a 6" rod in a small block Chevy. Next to impossible to see the difference. The short deck height Fords had a 5.4" rod.

As to revs...as many as you can get. If intakes and cams are open I imagine getting 10+k should be possible.

However, if all you want is 270hp and don't care to change the cam, intake, etc. that isn't an issue. I'd spend the money first on rotating and reciprocating weight...it is the same as horsepower without the stress issues.

There are lots of things to be decided: piston material (2618 vs 4032), piston rings and tension, wrist pin size, material, and coating, rod material, rod bolts, coating and features such as pin oiling. Rods also have design issue: I-beam or H-beam, through rod bolts or bolts that tread into the rod. It is possible to build the engine on the cheap; I think people have reached 2.4L with OEM crank, rods, and pistons. The crank has the same issues plus what size rod journal to use. SBC racing engines, at least in the under 500hp range, often use Honda's 1.88" journal. The S2k has a larger 2" journal. With custom components the smaller journal can be used reducing rod weight. However, racing is expensive and the question is whether an extra $3k-$4k in component selection will make a stronger engine. Component selection will also determine some of the maintenance issues.

The first thing would probably be to determine the budget, expected duty cycle, and constraints...such as the expected maintenance. If 25 cars show up in your class every week (say 15-20 times/year) and the entire field is separated by 1-1.5 sec/mile everything counts. If 5-10 cars show up for 5 races/year with widely different preparation levels being separated by 1-2 sec/mi between each car...decisions focus more on cost and reduced maintenance.

DavidNJ

Whats the biggest you can make an S2000 engine? I've seen pistons up to 90mm and strokes up to 106mm. That 's a 2.7L, fully 25% larger. To get to 2.5L a 90mm bore would only need a 98mm stroke. If it used a 1" compression height racing piston, that would allow a rod nearly identical to stock length. Note that a 1" compression height is very low and usually can have the oil ring over the pin.

f20kills

Some how this got really complicated for wanting a reliable 2.4 making 270 lol

There are multiple cars running a 2.4 here in CA making 270 and are tracked regularly.
None have blown up yet haha. Few use Wadziis kit and a few inline pro.

DavidNJ

This was an error. I misread the the piston big end bore instead of the journal diameter. It is a 1.88" (47mm) rod journal.

f20kills

Not an endurance car but inline pros and see track time..not a street car

https://youtu.be/26hZfl8R_is

DavidNJ

Its a matter of how much power you want to make. If people are reliably making 270hp with an 8000 limit with stock crank and pistons and a custom rod that's fine. However, would it be better if it could make 290hp or 300hp at 10,000 rpm? Or 280hp at 8000 rpm? I just took a swag at the power levels; 10k is 25% more swept volume than 8k. If it can breath the gain may be bigger than 10%.

Each of the differences adds a little a coating that increases combustion temperatures and heat transfer to the piston. Components with less reciprocating mass that take less power to accelerate. Coatings that shed oil to further reduce mass. Rings that seal a bit better. A larger bore that unshrouds the valves for a bit more flow. A higher rod length/stroke ratio that reduces peak acceleration and side forces at the piston. More cam to provide more flow. Removing VTEC to decrease valvetrain mass and resulting load on the valve springs.

If you are taking the engine down anyway, what is the marginal cost relative to the total cost of the engine or the car? I don't think this project fits in chumpcar rules.

BTW, what do you mean by "tracked"? Raced competitively or HPDE? I think this is for 4+ hour endurance races, several run on tracks that incorporate part of a super speedway.

f20kills

Tom Tangs 2.4 as well
https://m.facebook.com/tomtangracing

So yes..there are reliable 2.4s at the track so far.

f20kills

With money...anything is possible. If that's the case of course you can build a reliable 2.4 for an endurance race. Drop it off at your builder of choice. It will get done.They will know what it takes to get it done....or maybe you'll spend 15k for an Endyne engine for it to blow up on you lol....poor guy spent a fortune for an exotic build and it didn't last for crap.

I just saw the word reliable and doing all these changes doesn't sound reliable if you have a budget.

DavidNJ

i sent him an e-mail. However, he is running $6000 shocks (3-way JRZ racing), a custom intake, aftermarket fenders, wing and splitter...my guess is it isn't a budget engine.

f20kills

Tom Tangs 2.4 runs NASA. I don't know anyone in 2.4 form or stock form that runs endurance races.