Black_6spd

Last week, I was able to dust off some boxes in the garage and was able to find a good ol' collectors item: An original 1997 Integra Type R brochure.

While flipping through the brief, centerfold-styled pamphlet, I came across the changes to the ITR compared to the GS-R:
- High volume intake manifold, hand-polished intake ports
- Twin-coil intake valve springs with oval cross-section for high lift
- Lightweight, high-flow intake valves
- High-lift, high strength connecting rods
- High-rigidity, 8 counterweight crankshaft
- High-compression, low friction pistons
- High-volume airbox with repositioned intake for coller air
- High-flow exhaust system
- Torque-sensitive helical Torsen limited slip differential
- 15 mm lower suspension with 70% larger rear stabilizer bar, revised caster and camber settings and harder bushings
- Increased diameter disc brakes
- Front suspension aluminum tower bar
- Rear suspension performance brace

Believe it or not, that comprehensive list didn't even cover ALL of the changes. After all the changes, it amounted to a modest 25 horsepower bump over the GS-R. However, the numbers don't tell the whole story. Being a former Integra owner, I'd have to say that the Type R is 10x more fun to drive.

What changes happened in 2006 for the TSX?
- 64 mm throttlebody (previously 60 mm)
- larger intake valves
- higher lift / duration intake cam lobes
- larger header downpipe
- high-flow catalytic converter
- larger diameter cat-back exhaust pipes
- drilling to block design to reduce cylinder-to-cylinder pumping pressures

After all of those changes, it amounted to a tiny bump of around 10hp. Did the designers go through all of those changes knowing that it would only net a measly 10 ponies? For comparison's sake, a 2005 TSX owner could have paid $200 for an Injen CAI and would gain 10 hp.

I have a feeling that Honda designers were thinking more along the lines of a 20-30 horsepower bump similar to their achievements with the ITR changes. What happened?

Although I have my theories, I'm interested in knowing what some of the AZ'ers have to say.

dom

I seriously doubt they expected TypeR returns. And if they wanted TypeR returns IMO they could have had them.

And I agree about the TypeR being 10x more fun than a GS-R. My TypeR test drives are still the best Honda's I've ever driven.

Black_6spd

I think this is a fair possiblity. The earlier civic motors that went through many iterations only had small bumps in HP. It wasn't until the B16 Si motor came out.

The former design engineer in me is curious on why a company would invest design, prototyping, and testing resources to modify a design considerably while achieving almost negligible acceleration numbers.

STL

Black_6spd,
You have to look at more than just the peak differences. Compare the area under the curves you'll see the 2006 changes are more substantial than you make them sound (but still not huge or anything). Also be aware the differences at some RPMs are as much as 17-20 HP and close to 10 ft-lbs. I like the fact they made VTEC pack a good deal more punch (albeit it's still too short). Lastly, the improvements made to the 2006s should allow them to respond even better to aftermarket mods (like Injen CAI).

STL

Honda has done this before. They did almost the exact same thing when they dropped the multi-award winning 2.0L engine in the S2000 and put in 2.2L version (and they only did it for the US market).

BBriBro

Keep in mind the standard has changed in the way they measure horsepower. Lots of cars that haven't changed at all are showing LESS horsepower for 2006 (look at Acura's own MDX) so any increase is quite good. I think you'll find if you were to measure both engines the same way, it would be closer to the 20-30 HP you mentioned.

dom

Peak its nowhere close to 20-30 HP. More like 10-13. But like STL mentioned there are some nice gains in other areas in the RPM range.

dom

Standing start acceleration wasn't changed but the car was alot quicker in every other way was it not? At least thats what I recall TOV reporting.

And aren't the rest of the worlds S2K's now also using the 2.2? from 05 on I believe.

Black_6spd

The 10 HP bump I referenced in the first post above takes into account the SAE method. This figure comes from TOV. I believe Honda engineers gave a figure of 13 HP. Either way, it's still a far cry from 20-30 peak HP.

Black_6spd

Good points. This supports my stance that the Honda engineers intially had bigger expectations of their improvements. I think that the R/S ratio combined with inadequate cylinder filling at higher RPMs really limits the K24A2's ability to accomplish a 17-20 peak gain. Above 6000 RPM, the torque diminishes rapidly and cannot be helped much without FI.

The better question is: Why didn't they sacrifice some of the long stroke for the benefit of high RPM gain? My guess is Honda wanted to keep the TSX's low end power for everyday driving purposes as the "drive it like you hate it" continues to be a knock from consumers who previously drove high displacement / gas guzzling cars. Think about it: if Honda really wanted to make another 100+ HP/L, they could've easily done it again.

STL

From what I've gathered, the newer S2000 (or S2200 as I call them since that's what the should be named) aren't are as hardcore and are more forgiving than the original. So for the average driver they surely are quicker, but in the hands of good driver I'm not sure the new version is really much better. I think Honda took the edginess out of the car so it'd appeal to a wider market, but being that mine's not a daily driver it's the edginess that one of the things I like. I also really love the 9k redline!!

STL

I agree. My question is why didn't they look at Hondata's work and lower the VTEC point to 5k (or even 5.5k). I suspect they didn't want to lower the EPA milage numbers, but I wonder how much of a real world effect that would have had.

STL

I forgot one of my major points (talking about the S2200 versus S2000): a lot of the gains you see with the newer version came from the change in gearing and not the increased displacement. Ideally, Honda should have left the displacement alone (and thus retained the 9k redline) and just put in the new gear ratios. I suspect they didn't do this because of " low end power for everyday driving purposes" arguement -- thus theoretically making it appeal to more people.

STL

I see that I mispoke above, here is what I meant to say:
"...a lot of the perceived gains you see with the newer version came from the change in gearing..."

dom

I don't think you mispoke at all.

I've never driven or ridden in an 04+ but from all the reviews I've read the only downside was the lack of a 9K redline.

Black_6spd

Although I haven't driven one either, the many S2000 owners were dissapointed to see DBW / VSA get added. (But I do like the newer rims.)

Dom - of all the Honda VTECs you've driven, isn't the ITR the raspiest and meanest cam lobe transition around? The one I drove happened to have an AEM CAI. Pure joy after VTEC crossover....

STL

I believe Jeff (at VTEC.net) even noted in his '04 review that the new gearing would be better suited for the 2.0L than then 2.2L -- and the that 2.2L might be better suited to have the old gearing (since the redline is so much lower).

Many reviewers of the original S2000 also complained about the ride the too harsh and hardcore (heck some even complained about the shifts being too short), but as I said beofre since mine's not a daily driver I want a the hardcore race-car feel. So I can totally understand how many reviews would consider the softening of the car a good thing -- but I don't.

STL

Black_6spd,
I've never driven an ITR, but I heard they are a blast. You should find a S2000 (not S2200) to test drive. While I've heard the ITR was even more raw, you might be surprised how good the VTEC transition is in the original S2000.

dom

Indeed. I've driven 3, each time coming directly out of my AEM CAI equipped GS-R and the car was simply head and shoulders above the GS-R. Very Raw but so controlled.

I kicked myself for 2 years of GS-R ownership about not buying a Type R.