bbsilver

You can't compare a rotary engine to a piston engine. Different animals. An equiv. comparison would be if you multiplied the rotary displacement by 3. The 1.3L turns into 3.9L. Also the RX-7 is a turbo while we are n/a.

fluxen

[QUOTE]Originally posted by bbsilver:
[B] You can't compare a rotary engine to a piston engine.

Luis

Certainly not. Any of the new high pressure common rail diesel engines will leave the S2000 in the dust.

No one in their right mind would dispute that the S2000 engine is probably the worst base to improve upon (ok, not the worst, you still have the Maclaren F1 and one or two Bugattis). But as many people have pointed out the S2000 engineer did not have a blank check in their hands. They designed to a budget.

20HP is not hard to achieve without forced induction, just expensive.

Get a Mugen header and a free flow single pipe exhaust like the Amuse and you're close.

Add intake mods and you're there.

Get a Spoon head gasket, a Mugen/Spoon ECU and decent gasoline and you're over.

Expensive? certainly. But hardly undoable.

bbsilver

2X ... 3X, either way it is not a direct comparison. At 2X it is 107HP/L, so just a bit shy of the S's 120HP/L. What I would have like to see was the rumored 3rd ring-Tri-turbo for the RX-7 before it's demise. That would have been scary quick.

Bieg

I should have specified, GASOLINE AUTOMOBILE ENGINE. Once again apples and oranges.

Regarding all the other mods, ... has anyone done it or are you just adding up the individual improvements for each item and assuming they are cumulative?

Also raising the compression (I assume that is what the head gasket mod is doing) so you need to run Cam-2 racing fuel is outside the spirit of this disscusion.

The reason I ask is I have yet to see a report on an S2000 with a 20 HP or better gain (with the provisions as stated previously).

I figured someone would have one by now if it was feasable.

Tedster

I agree that the Honda engineers did a fantastic job, but that they had to work to a budget, and end up with a livable, reliable car.

I think it's a good idea to ask about any particular mod 'why didn't Honda do it this way originally?'

In many areas it seems that they've done about as good as possible without raising the price significantly (e.g., exhaust).

But other areas don't seem as clear.

For instance, why not use a K&N type air filter?

Why is the throttle body the size it is?

I really don't know, but I'm sure others here have some pretty good ideas. What do you all think?

Tedster

1Randyc

I do believe I achieved more than 20 hp at the wheel although I don't have the dyno figure to prove it to you.
So far I have ATS final gears which alone gives you 10% more hp and Amuse R1 exaust with 7-9 hp, HKS racing header ?hp+, Mugen Intake and ECU ?hp+, Toda flywheel...
Next one coming to the addition is Back Yard Special Straight Pipe in place of the cat..
Also throttle body soon...

[This message has been edited by 1Randyc (edited October 17, 2000).]

Pepe

Let me give you a few ideas.

Lets take the Throttle body for instance.

1. More material on a bigger butterfly=more money multiply for total car production=$$$$.

2. Honda may not manufacture the TB so probably this was the size that the OEM manufacturer had in stock and entered the bid for parts in the s2000 with.

3. Tapper bore=more work which equals more money

4. Safety Net: Very few manufacturers build engine to the edge. They always leave something and in most Hondas this something can be significant.

Bieg

Gears don't change engine HP. They may be more efficient (less friction) so you lose less to the rear wheels but they don't add any HP.

The HP you have will be more accessable at lower speeds if you lower (raise the number numerically ie: 4:56 instead of 4:11) the final ratio but that does not increase HP it just shifts it to a lower speed.

In other words changes to gearing don't count.

Bieg

One should also keep in mind that engine tuners are not necessarily always looking for the highes PEAK HP number but rather highest HP through the broadest range. It would be easy to get a higher maximum number in a very narrow RPM range but the car would not be as fast as if you got slightly less over a larger RPM range.

I think that is why Honda made some of the choices they did. In the bike world guys would bolt on certain pipes that made slightly higher peak numbers but at great expense to the mid range. Foolish in my opinion unless you were just going to drag race it and keep it at redline all the time. Not a real good choice for the street and actually made the bike slower in the real world.

That is why an accurate dyno chart is what you need to go by (before and after on the same engine under the same conditions) before you can say you made a successful modification.

I believe that many HP claims by the manufacturers are flawed in one way or another. For instance any 2 S2000s will have slightly different HP outputs. Find the hottest stock one from the factory and bolt your "Modified" parts to it and use it as your "after" car. Of course find the weakest one and that should be your "Before" car. Of course run your "after" car on the dyno on a cold day and your "before" car on a warm day. Use synthetic oil on your after car and regular oil on the before car. Just messing around like that can generate some impressive numbers for your advertising department.

I also believe that people who spend much money on aftermarket parts are a little hesitant to admitt that they really did not pick up as much HP as they imagined they would.

Going with a larger throttle body I am sure picks up peak HP. I will bet you it loses HP in the midrange though and that might not be an acceptable trade off. Does anyone have the before and after Dyno charts of their own car on this modification?

Rule of thumb on intakes and exhaust is the larger you open it up (to a point) more HP at peak revs but less midrange.

Shifting HP around the rev range is not really the same as increasing it throughout the whole range. I am sure many of you already know that but some may not and that is the only reason I am saying it now.