Ivester

Alright I love my TL. It's a flawless car in my opinion. The only thing I noticed is since I have an automatic if I'm casually driving around the car upshifts to like 5th gear going 30mph. I assume this is due to the drive by wire and helps with the mileage. Since this is annoying when you want to bomb around I constantly find myself using the tiptronic, which makes hitting 6,000rpm a breeze in the lower gears with minimal effort. Good times.

However I was forced to drive my friends G35x the other night and I couldn't help but notice how much more low end kick that car has. It felt like the car never upshifted until it absolutely had to and stayed in the lower gear as long as it could. It made for some interesting moments whenever I came to a stop sign.

Question is - is the g35x that much more powerful in the low end because of the 50hp? The drive by wire sensitivity? or is it because the engine gets a bulk of its power at a lower rpm compared to the acura's higher rpm power? or none of the above.

Flame away if you don't feel like helping me with understanding this I'm trying to learn this stuff, one day at a time.

JwongTLS

DOHC > SOHC

thats where u get the low end tq

Ivester

Thanks that gave me enough to research on to understand fully.

Ivester

Hrm...double thanks. This also helps explain why the engine having VTEC is what gives us our decent HP at 6,000rpm. If you were to turbo charge this engine, it's basically doing the job of the VTEC with a lot more punch?

csmeance

not quite! VTEC allows the engine to have two different profiles. In one, the engine breathes in moderately to produce moderate power, thus allowing for great fuel efficiency. Then there is the other profile which allows the car to suck in as much air as it can to produce the most power it can.

Honda pioneered this technology, and it seems that other manufacturers are taking advantage of it while honda sits back.

Turbo on the other hand forces more air into the engine than it would normally suck in. More air means more fuel, which means more power.

I hate cars

Cam in block, SOHC, DOHC, doesn't matter. Typically a DOHC and SOHC engine is tuned for more top end power due to the lighter valvetrain. However, I've seen tons of 400+ cubic inch engines with no overhead cams spinning 7,500+rpm.

The following applies to modern engines.

SOHC makes it easier to alter overall cam timing. Engine management can advance and retard cam timing in some engines. This allows better low and high end and slightly better emissions. The difference is subtle.

There is also room for some form of "vtec" since the cam is in the heads and not in the block.

DOHC in a modern engine has the same advantages as a SOHC but also allows the engine management to alter intake and exhaust overlap even further helping low end, high end, and especially emissions more than anything else. Plenty of room for "vtec style" hardware.

In the drag racing world, SOHC and DOHC don't offer much of a power advantage. You can get more overall valve area in a combustion chamber out of 2 large valves than 4 small valves. Low end is not an issue when you're dealing with large engines, turbo engines, or a car that is properly setup to deal with a high revving engine.

Where the OHC engines shine is in the ultra high rpms arena. No pushrods, usually no rocker arms, a larger cam base circle, much less valvetrain weight, and springs with much less tension for a given rpm range make for a more reliable valvetrain at ultra high rpms. reliably. When I say ultra high rpms, I'm speaking >9,000rpm. My father's pushrod V6 in his GN spins close to 8,500 just fine.

The answer to the question is the Nissan engine is tuned more for torque, that's all. Honda is notorious for tuning for high rpm hp without much care for low end torque. Vtec helps with both somewhat but personally I prefer the torque especially in a daily driver. It makes it so much more relaxed to drive without having to downshift all the time.

Ivester

Damn I wish I was born with a wrench in my hand. It would make the learning process infinitely easier. Thanks for the information.

TSX-S2000

Generally, the larger the engine's displacement the more torque it'll produce. Nissan's VQ engines have always been known for producing good low-end grunt.

As "I hate cars" stated, Honda likes to tune their engines for higher-rpm performance. The engines just love to rev and feel like they can do it all day. An extreme of that example is the S2000 (I had a 2000MY) which didn't wake-up until 5500 rpm (again: small engine, very little low-end torque, high rpms required to generate 240 hp).

I also had two G35 6MT sedans and they definitely had more low-end torque (not comparing to the S2000 but the TL). However, they sounded like they were going to come apart above 5000 rpm (noise and roughness).

Which is better? It comes down to personal tastes and the type of driving you do. The S2000 wasn't fun around town so you can see how a good amount of low-end torque makes city driving much nicer.

Ivester

I think I prefer high end torque overall. The low end I experienced in the g35 was just night and day to my TL's so I was surprised. I never got the car above 60 so I have no idea how it was at higher rpms. Nor did I try the tiptronic in it. I need to drive more cars I guess :p

avs007

I don't know if you care, but a long time ago, I made some audio clips, of revving my TL and G from idle to 6800rpm in 2nd gear.

TL Sound Clip

G Coupe Sound Clip

Before I put the spacer and Z-tube in the G, the TL's engine was louder once the V-TEC kicked in... After I installed the Z-tube and spacer, the G was louder. This sound clip was pre-intake mods..

scv76_

If your TL is shifting into 5th at this speed, I would have it checked out.
My 07's lowest shift into 5th occurs at a minimum of 37 mph.
Actually, according to the rpms, it's not really even into 5th gear...sort of somewhere between 4th & 5th gear. There's a name for that but I don't remember what it's called

AMUA6

iTrader: (7)

As scv76 said.. I don't hit 5th gear in auto moder until 50+, and that's not driving it soft.

avs007

You talking about Torque Converter Lockup?

6spdtl-s

iTrader: (1)

VQ = low end torque

Honda = no torque.

SmileyOr

Torque = get to top speed quickly.
HP = get to higher top speed.

Given the same size engine and tuned differently. The way I understand it is that the engine can be tuned variably. If you drive around town on a daily basis and never plan on getting anywhere near top speed. An engine tuned for max torque would be more useful. If you are racing and need top speed (track with more long straights and high speed turns) you would want higher HP.

Ivester

Sorry I typed it quickly and just threw an example out there. I'd be in 4th but I'm commonly in 4th going 30 if I'm not pushing it hard and it can be super annoying sometimes. It's fine though just something I didn't figure out until I read through the manual a bit and saw the pre-determined speeds at which the gearing *might* upshift at.

At first though I thought something was wrong. Just had to figure out the car a bit. I'm starting to really enjoy 2nd and 3rd. Coming from driving a camry and honda pilot for a long time, try to understand

scv76_

Yes I think that's it

TSX-S2000

I had the Z-tube and Stillen intake on my G and with a mid-muffler delete, it produced some very nice sounds. However, what I meant to say was that the engine had some harshness and roughness when it was revved hard. It definitely didn't seem like it enjoyed being in the upper RPMs as Hondas do.