Over the last seven months I've purchased five roadsters. Might be a mid-life crisis. I'm having fun, what can I say. I'm planning to sell all but one.

97 BMW Z3 MT
2007 MB SL550 Auto
2005 MB SLK350 MT
2006 Mazda MX-5 MT
2006 Nissan 350Z Touring Roadster MT

The SL550 is by far the best of the lot in terms of pure performance, and it is the most comfortable and refined of the lot as well. But the one I have the most fun in is the 350Z and it's a keeper. I really love this car.

Would it surprise you to discover that my SLK350 can out-accelerate the 350Z quite handily? It is significantly faster. Here's the specs on both:

2006 Nissan 350Z Touring Roadster Manual Transmission

3.5ltr V6

300hp

260 lb/ft torque

Curb weight 3600lbs

0-60 5.6s



2005 Mercedes SLK350 Manual Transmission

3.5ltr V6

268hp

258 lb/ft torque

Curb weight 3230lbs

0-60 5.9s


The SLK has acceleration that really sets you back in your seat and I just don't get that with my 350Z. I'm not unhappy with the amount of power my 350Z has - It's just fine - but there's such a difference in the way it feels as compared to the SLK, it makes me wonder if there's something wrong with it. It doesn't feel like 300hp to me, it feels more like 225hp. The car has only 23K miles on it and it's been completely gone through by my mechanic. I don't notice any issues while driving, it accelerates smoothly and revs freely up past 6K.

Here's a little tidbit of info. With the SLK I feel like I'm getting more power and acceleration if I rev all the way up to 6000rpm. With the 350Z, I feel like I get the same power and acceleration if I shift into the next gear at 4000rpms - like I'm not really going to accelerate any faster if I let it rev to 6000rpms.

One thing to note. When I bought the car there was no muffler in it, and I took out the cat-back straight pipes and replaced it with a used oem cat-back with muffler. I don't remember noticing a decrease in power after adding the muffler, but I wasn't really paying attention to that. I was enjoying not having to listen to the dreaded 3K - 4Krpm drone anymore.

I'd love to get some feedback from those here who have a lot of experience with 350Z's. Is what I'm noticing with the power of my car normal? Is this just how these cars are? Or do you think I should be looking for something that could be wrong with the engine that would help it to feel more like it's got 300hp?

If you're nearby to Middle Tennessee, you're welcome to come for a drive with me on the wonderful backroads we have around here.

Thanks for helping out a 350Z newbie.

Pics to help make this thread more interesting.

Greg

 

Well, considering the fact that the Z reaches 60 three-tenths faster than the SLK and is some 370lbs heavier doing so, I'd say that there's nothing wrong with the Z. (Or are these just book figures, not real world measured?)

Either way, pull codes and see if there's anything showing up or stored. After than, you can look for more but the SLK is a pretty quick little car. Not SLK32 quick but still. It could also be that huge weight difference which gives a different feel.

 

You're most likely feeling the effect of different gear ratios between the transmissions. Here are the figures for both cars:

SLK350
1st - 4.46
2nd - 2.61
3rd - 1.72
4th - 1.25
5th - 1.00
6th - 0.84


350z
1st - 3.794
2nd - 2.324
3rd - 1.624
4th - 1.271
5th - 1.000
6th - 0.794

The higher gear ratios in the Merc should make acceleration feel faster, at the detriment of top speed. Vice-versa for the Z, the lower gear ratio might make acceleration feel a bit slower, but you'll gain a higher overall speed in the process.

I'm no transmission engineer or expert by any means, but I'm fairly certain this is what's causing your seat-of-the-pants difference between the 2 cars.

 

Book figures - posted specs. They are not accurate. I haven't measured, so I don't know if my 350Z is slower than spec or the SLK faster or a combination of both. In a 3,2,1 GO head to head, the SLK is a few car lengths ahead of the Z by the time we reach 60.

SLK32 and SLK55 are automatic transmission only, which is why I passed on those. I'm glad I bought the SLK to try out, but I'm going to sell it. It's a fast car, and handles extremely well on twisty roads, making a blast to drive. It's an odd mix of typical Mercedes quality combined with some cheaply made bits here and there. The suspension is crude over anything but smooth pavement, and the body/roof is creaky/noisy. The seats are not comfortable and it's a little too small for me.

Greg

 

I think you may be right about that. Although they both have a top speed spec of 155mph.

Greg

 

I can guess it's probably the torque difference you are feeling, that being said if you want the same feeling in the Z and aren't concerned with spending some money it can be had.
Get an MREV2 and spacer, a 3.9FD and a proper LSD and the car should be a blast to drive.

 

Hi Greg,

Welcome to the 350Z Revup club (specific to the 05.5 - 06 6MTs). To really "wake up" the engine in your Z at minimal cost, get yourself the Motordyne MREV2 lower plenum + Spacer kit. This one bolt-on performance mod really shines specifically on the Revup VQ35DEs. Expect to gain 30+ ft/lb of torque and nearly as much hp without a tune. With some tuning you can expect some more gains. If there's any one thing you do that will have a noticeable impact at a very low price point, this is it. Visually this bolt-on is barely noticeable, very stealthy. It will not alter the sound or look of your engine bay. I highly recommend it since you plan to keep the Z.

Sample Dyno Chart from my Revup VQ after tuning with exhaust and MREV2 boltons.


More about the engine you have. Even though the Revup variant has a higher redline (7k vs. 6500RPM), it produces peak hp at around 5800-6000 RPM then noticeably drops off. So if you're slamming through those gears, that's where you want to plan your shift point. The DE has excellent mid-range torque as my sample chart shows (peak just above 4k RPM) which you've already discovered. But your comment about not feeling a noticeable difference above 4k is indeed strange/abnormal. I suspect the previous owner "may" have tuned the engine for the straight pipe exhaust. By moving back to the OEM exhaust, you have altered that tune which may have caused some negative side effects. This is purely speculation on my part, but might help explain the perceived lack of power above 4k RPM. A dyno tune at a shop would give you more definitive proof/evidence that something is amiss. Also, if the previous owner ran a straight pipe exhaust, maybe the MREV2 plenum is already there or an aftermarket intake? Getting a picture of the engine bay would be most helpful.

My final thoughts....I'm a bit surprised that the Merc's curb weight comes in under the 350Z. I would have expected all the added sound deadening/insulation and electronics commonly found in German cars to bring the weight above the Z. The gear ratios do explain some of the equation here (Good info from lifekenophobic). But I don't think that's the whole picture, the Z still boasts a lower 0-60 time, so all things considered, it should both feel and be faster unless something isn't right. One thought that popped into my head after reading your notes is the potential for a slipping clutch. Even though your Z has low miles, that doesn't mean the previous owner was kind to the clutch. I purchased my 06 Coupe with low miles (44k) and the clutch was toast. Under the right conditions it would slip really bad and could make the vehicle feel like there was a lack of power/acceleration to the untrained eye (or butt dyno).

I would investigate the possibility of slipping clutch and an aftermarket tune. Once that is determined, I would slap the MREV2 on there, get a tune and enjoy. There's plenty more improvements/mods I would be happy to recommend, but getting this lack of power issue handled takes priority.
Cheers!
-Icer

 

Looks like Dark beat me to the MREV recommendation while I was writing my thesis! doh!
-Icer

 

Great info here, thanks guys. I have more questions now.

1. What is a 3.9FD?
2. What is a proper LSD?
3. What's the Revup club?
4. What does 'tuning' mean exactly?
5. Can I visually inspect or otherwise test it myself to see if my car was tuned by the previous owner for the straight pipes? (Rather than Dyno test)
6. Would air intake and exhaust mods help? Is that part of the 'tune'?

The MREV is something I'm interested in doing and it's really cool that this is available. I like how it improves things in the mid-band. I like shifting at the 4K - 4.5K point and I consider this 'spirited' driving on the backroads here in TN. Running up to 6K seems excessive to me (even if it is supposed to be quicker), and it upsets the wife, who is usually sitting beside me and within back-hand wacking distance. (by the way, I do realize that shedding that weight to the right of me would help the car go faster! I hope she doesn't read this, lol)(actually, I enjoy her company and I'm glad that nearly every day we can share the fun of top-down backroad driving in a fine car like the 350Z - very lucky)

My clutch engages a little late in the travel of the pedal, but seems to engage fully right away, especially shifting with speed in third, fourth, and fifth.

To clarify my comment about not noticing much above 4Krpm. The car certainly continues to accelerate above 4K right to 6.5K and it's nice acceleration. I may be wrong, but my gut tells me that a shift at the 4.5K point to the next gear with full throttle would result in the same acceleration. One thing that is interesting about this car over any of my others is that whenever I shift to the next gear, the car seems to pull best immediately after the shift. I call the car 'eager' because of this. There's that initial burst of energy and eagerness right after a shift, and then it seems to fade and is just not pulling the way I think 300hp should pull. Overall I want you to know that I'm not really complaining and I don't think there are any major problems with the engine and I know I am being picky - my point in bringing all this up for discussion is to investigate and learn. So far this thread has been enlightening and I appreciate all the input. Heading in the right direction.

Greg

 

I'll answer a few things here:
1. 3.9 FD is the Final Drive gear, the stock for the 6MT cars is a 3.5 so the 3.9 will put more torque down at the expense of some rextra revs at cruising speeds.
2. LSD or limited slip differential will just let you put the power down better and increase traction out of corners. The touring and track/GT models have a viscous unit but it's not all that efficient at its age.
3. Intake is more noise, the 06 air box is really good, just get a good filter for it.
4. Exhaust does give some gains but TBH, if you ask me the MREV2/spacer is a better bang for your buck and so is the FD.

As far as tuning there are a lot of options so it's hard tohsay if it would be detectable at all.

 

Is the Final Drive gear in the transmission or the differential?

Pop Charger claims 5hp gain and is supposed to sound good too.

I'd done some reading on what it means to 'tune' a car. Seems like that's something best left to a professional, preferably one with a dyno so the gains, if any, can be verified.

I've discovered that I live just four hours drive from Z1 Motorsports! I think bringing my car to them might be a good option. More expensive, but easier than DIY, and the results of their work will be verified by dyno testing.

Here's what I'm thinking:
MREV2
Z1 air intake
Z1 dual cat-back exhaust
Tune and dyno-verify
New sway bars
Maybe change FD - I do like that idea - depends on cost

I realize this is pretty tame stuff compared to what can be done, but I really like the car the way it is and I'm not looking to change the characteristics of it all that much. A bit more seat of the pants pull in the mid-band, a little bit deeper tone to the exhaust note, and reduce body roll heading into a corner. Probably going to be $5K at Z1 and I think well worth it.

Greg

 

Do all....and I mean ALL breathing mods before or at the tune.....if not, you will be paying again

 

That is basically a textbook NA set of parts and I believe you will be happy with that. I would add high flow cats, and call it a day. Z1 will be able to establish if you have an issue at the same time too.

 

I'd forego the intake, I've had 7 at this point, none are as consistent as stock 06 box, unless you want the sound.
You need the MREV2 + spacer to maximize gains.
The FD is in the differential, which is why I always recommend doing a LSD at the same time as it's free labor.

The alternative way of doing it is getting a 3.7 VLSD pumpkin from a 370z and swapping that for a little extra acceleration with minimal costs, if you're buying new, it only makes sense to get both the 3.9 and LSD.

For the cost of the Z1 intake I'd change to Berk HFC (I like those over the Z1, had both) since there is a slight chance one of your cats could be damaged and that is causing the sluggish feeling.

 

For the intake, I'd go with the AEM. That's what I had. It's a true cold air intake, as it moves the filter out of the engine bay. It also sounds great. If you don't want your car to be loud, leave the stock cats and save yourself some money.

 

Compared to all my other cars that are around 300 hp, the z feels the slowest and least powerful. The gearing is also long making it feel more sluggish even with a 3.69 final drive and NA mods.

 

I'd like to take a moment to appreciate the nice photos

 

Hey TN,

Most of your questions were already answered. But I can elaborate further on the Revup VQ. You have an 06 6MT, so you got the one-off year engine that could come in a 350Z.
03-05 had the standard VQ35DE (whether it was an AT or 6MT)
05.5-06 had the Revup VQ35DE (initially introduced on the 2005 Anniversary Edition I think)
07-08 had the VQ35HR (final evolution before the 370Z came out)

What makes the Revup VQ35DE different from prior years, was the intake and exhaust variable valve timing, also the oil pump was upgraded along with some of the rotating assembly internals. These improvements allowed for the rev limit bump to 7k and some good power increases compared to the years prior. It's a sweet engine, but became notorious for oil consumption issues. Nissan had a TSB campaign out for this engine and did offer Warranty replacement long or short blocks if a Nissan Dealer determined you had excessive oil consumption.

Because of these oil consumption concerns, I strongly recommend sticking with the factory 06 Air Filter Box. You get the best filtration/protection with the OEM filters and maintenance is a snap. Aftermarket intakes (Cold Air intakes) + cone filters do give some minor power gains, but those filters require regular cleaning and re-oiling to keep larger dust particulates from entering your intake (many users don't do this crucial service). Besides, your 06 filter box was also an improved design over the previous years which included a velocity stack from the factory. If you do decide to upgrade your intake system beyond the MREV2, I think a larger throttle body and something like the Mishimoto Tube would be better choices for the long term, especially since you don't like to rev your engine beyond 5k-6k, which is where most gains from a CAI cone filter or pop-charger will really shine. Your biggest gains will come from the exhaust, MREV2, and a tune (unless you take the nuclear option & roll forced induction with either a turbo or supercharger kit!).

If you wish to focus on utility and driver comfort, then I highly recommend the RJM Performance Clutch Pedal. Especially since you mentioned the clutch engagement is at the top of the pedal travel with little room for initial bite or feel. This single mod is a must have in my book for those with 6MTs, it greatly improves the feel and control of the clutch engagement duration and initial bite....and it nets me an extra 10 SPG (Smiles Per Gallon).

Next I would get your rear differential bushings replaced. If you do decided to change up the gear ratio on the diff, that would be the time to also replace the bushings. The rear bushing is fluid filled and they all fail from age. If you have a black/brown stain trail on your rear subframe, then the bushing is blown and should be replaced. Yours may still be intact with how low the mileage is, so worth a check.
Cheers!
-Icer

 

Wow, such good information here guys. Thank you. Is there a way for me to change the original title of this thread?

I got a quote from Z1 for $5,300 for parts and labor. Here's their recommended list:
Z1 cone air intake $250
Z1 350Z / G35 Carbon Fiber High Flow Intake Kit - CARB LEGAL - Z1 Motorsports - Performance OEM and Aftermarket Engineered Parts Global Leader In 300ZX 350Z 370Z G35 G37 Q50 Q60
Plenum spacer $220
Z1 350Z / G35 VQ35DE Plenum Spacer - Z1 Motorsports - Performance OEM and Aftermarket Engineered Parts Global Leader In 300ZX 350Z 370Z G35 G37 Q50 Q60
75mm throttle body upgrade $316
Z1 Motorsports 350Z / G35 VQ35DE 75mm Throttle Body Kit - Z1 Motorsports - Performance OEM and Aftermarket Engineered Parts Global Leader In 300ZX 350Z 370Z G35 G37 Q50 Q60
Z1 catback exhaust $1,550
Z1 350Z Cat-Back Touring Exhaust - Z1 Motorsports - Performance OEM and Aftermarket Engineered Parts Global Leader In 300ZX 350Z 370Z G35 G37 Q50 Q60
Performance sway bar kit front and rear with links $775
Z1 350Z / G35 Performance Sway Bar Set - Z1 Motorsports - Performance OEM and Aftermarket Engineered Parts Global Leader In 300ZX 350Z 370Z G35 G37 Q50 Q60
UpRev license and mail-in reflash and I also assume they have figured in before and after dyno verification since I asked for that $400
Labor $1,500
Tax/shop supplies $320
(my math may be a bit off, just rounding)

Missing the MREV2 (or the Z1 plenums), which I really would like to have

How much gain is there from their throttle body upgrade? and is there an alternative?

The Z1 catback is eating up a lot of my budget, but they claim an extra 20hp. I wonder if there's an alternative - I know there's a ton of exhausts out there and I love your suggestions, but please remember, I do not want a drone and I don't want excessively loud

Things I'm unsure of and a little concerned about at this point - drone/noise from the exhaust and the ride of the car being affected a lot by the sway bars stiffening up the suspension. I'm thinking about attending a large gathering of 350Z owners to listen to the different exhaust notes. Where and when?

I love having all your input, please keep it coming.

Greg

 

I am leaning towards just keeping the stock intake housing. I purchased a high-flow K&N filter and it should be here today. It will be interesting to see if I can tell a difference.

I do want the MREV2 and spacer.

Do you know if a 3.7 VLSD pumpkin will bolt right in? Spacing with the driveshaft? what is the final drive gear?

Greg