when i installed HFC my car was a slug - it pulled timing due to lean condition... Tadashi at TS added fuel and I felt a bunch more trq (didnt dyno right away, but all dynos since then have been quite a bit better than they were previoulsy)...

 

Great to know. At least we know the HFCs are doing something (aka making the flow greater to cause a lean condition)

I think I'll go with HFCs and forgo the headers. Then find someone that can tune my early ecu

 

I'll be getting headers - but only when I do cams too... Osiris cam adjust cam angle so I have high hopes (and will probably be let down, but you never know)...

HFC are definitely worthwhile with a tune... but this has been said many, many, many times...

 

Normally DynoDynamics are the lowest reading dynos, DynoJets are in the middle and DynaPacks are the highest. The important thing is to do all your runs on the same dyno as close to the same time/weather as possible.

I have been on a similar route to you, except that I originally went with UpRev's Osiris to flash my ECU. Later I switched to a Haltech and had my car tuned at the Performance Factory by Jeremy Tibbs. I still use Osiris for the rev limit and other drive-by-wire limitations of my revup ECU.

I originally dyno'd 268 horsepower with the Osiris tune. After about a day of tweaking, my G was up to 286 horsepower. It's not the most NA horsepower to run on Jeremy's dyno (a DynoJet), but it is the highest with stock internals. I bought an oil consumption engine a few months ago and am in the process of building it to go in my G. Should be fun...

 

Here's some MPH data to consider re: the power adders on the car so far.





If you look at the Max MPH for the straight away sections, in particular segments 1-2 that follows Turn 1 which is a horrid understeer/plough inducing turn that's impossible to carry any speed out of, which makes the 1-2 straight away a real test of engine performance/power delivery. As you can see from the data, we picked up 4 mph from the bone stock setup to the current setup, which may not sound like much but believe me that's a huge huge difference in road racing terms. It's probably about the equivalent of going a full second faster in the quarter mile, if not more.

Agreed that in logical terms a Dynapack should read higher since the wheels are removed from the equation (so it's hub horsepower, not wheel horsepower), but in reality it is (as somebody else pointed out) all about calibration, and it's all a moot point if you use the same dyno from OE baseline to the end of the build like I'm doing with the U2Ndyno.com, since a dyno is simply a tuning tune and a way of measuring gains, not a comparative tool where you can compare results from dyno to dyno. But since it's human nature to want to compare results, it is worthwhile noting that the Dynapack I'm using does read lower than the Dynojets we have here in town and on par with the Mustang dyno in town.

A/F is definitely a bit on the lean side. I'll post all the A/F results once I put together the Haltech/Technosquare story for the mag.

 

The only reason I bring up the Dynojet into the equation is because that's what I have experience with. On average, a Dynapack will show about 10% (20% was a mistype on my part) more power to the wheels. However, the Dynapack is a brake-type dyno which means the operator can influence load and essentially try to bring the numbers down towards those of the Dynojet. The Dynapack as well as the Mustang dyno (another brake dyno) are actually better than the Dynojet because they can allow you to tune for varying loads (ie simulated grade, wind resistance, etc). However, the Dynapacks do usually kick out higher numbers. 260whp on Dynapack usually coorelates to around 235-240whp on the Dynojet. The overall numbers really don't matter here, but I think in terms on Dynojet numbers and it's been my experience as well as many other guys that modify and take their cars to the strip that a solid 10whp gain across the powerband on the Dynojet equates to about .1 seconds in the 1/4 mile. That's all I'm talkign and why I brought Dynojets up.

 

Well, I understand that his car may make some gains more gains with the tuning, but right now, the way the car sits, it's probably not much quicker in the 1/4 mile. Here's why: 1st gear will be total weak sauce as well as portion of 2nd. Not until 3rd and 4th gear will the car come alive. The headers totally neutered power below 5000rpms. The HFCs definitely helped things, but the car is still slower during that very critical 1st gear punch and for a short period of time into 2nd. This is far more damaging to acceleration than people think. Let me tell you a story. It's a long story but I think it's very useful in describing where I'm coming from here.

I had a 96 Maxima and a few of us got a hold of an intake manifold from the 98/99 Middleastern/Aussie Maxima which was able to let the VQ30 make power all the way to the 6600rpm fuel cut. With the stock manifold, power peaked at 5900rpms and dropped like an anvil after 6100rpms. With some bolt-ons and stock intake manifold, my car made 183whp and 193wtq. The car ran low 14.6s@96mph. I then added the new intake manifold and the car made 189whp@6200rpms and carried nearly all that power to 6600rpms. Compared to the stock intake manifold, the new intake manifold made the same power at 5900rpms, 12whp more at 6200rpms and a massive 45whp more at 6600rpms (187whp vs 142whp). From 2500 to 5000rpms, the new intake manifold neutered power by 5 to 12whp/wtq. I thought how could such an insignificant loss impact overall acceleration? I was wrong. I took the car to the strip on two seperate days (same strip I've always gone to. very similiar conditions) and the car was no quicker, if not fractionally slower. How could this be? The car was making SO much more power up top. It turns out that hurting the midrange power is VERY determental to the 1/4. My 60' were the same, but the 330' were a bit slower as well as 1/8 mile ET/mph. The car made up some ground in the last 1/8 mile where it was quicker and faster, but it wasn't enough to overcome that initial 330' deficit. I quickly learned that midrange power is extremely important and big gains in the last 1000rpms of the powerband really don't do much in terms of acceleration. Luckily, JWT made an ECU flash and I got it. It raised my rev limiter to 7100rpms and it restored midrange power. The extended rev limiter really was essential because it allowed the car to ride a fatter and longer powerband. With just the ECU, the car went 14.3s@99-100mph and was making on average 20whp to 50whp more across the powerband compared to the stock manifold and 6600rpm rev limiter.

That little experience the intake manifold completely changed my thinking when comes to looking at "gains". I now look closely at the losses to make sure they're not going to impact the overall acceleration of the car. I don't have much doubt Dave's car is posting faster MPHs on long high MPH straights, but I'm also pretty certain his car isn't much quicker in the 1/4 mile either. Now if these mods elevated the entire powercurve up by 20whp/20wtq, his car would much quicker in the 1/4 mile. I would MUCH rather have a 10whp elevated powercurve than a 20whp gain from 5600rpm to 6600rpms because the 10whp gain can be felt and seen in the terms of 1/4 mile times.

 

^i see what ur saying, one critical difference between the Maxima and our 6MTs is the how much shorter our gears are. Maxima having tall gears u would need all that midrange power to actually be faster. I am guessing the only time he will see "lagg" if any is when shifting from 1st-2nd. The first gear power can be adjusted by launching at higher RPM and let the clutch pedal control the power/wheelspin. That means launching at 5k rpm and staying above that rpm throughout the first gear, like i was doing on my last trip where i got consistent 2.1 60ft times, would not slow him down at all atleast in 1st gear. Im not sure what exact RPM land when shifting to 2nd gear but i will check it out when i go to work tomorrow.

I can definitely see ur point though.

 

I agree, the Maxima does have taller gearing (7% in 1st, 13% in 2nd, and 18% in 3rd), but it's tire ratio is about 5% shorter which equalizes some of the tranny gearing deficit. The Maxima is also anywhere from 400lbs to 500lbs lighter than a G coupe/sedan. But anyways, yes, Dave could come off the line at 5000rpms though I'd think it would take some pretty brutal clutch slip to maintain those rpms straight from the launch. Hopefully he doesn't have a lightened flywheel because that will make the situation far worse in terms of 1st and 2nd gear acceleration.

BTW, does it really take a 5000rpm launch to get a G 6MT into the 2.1 range? My auto comes off the line at 2400rpms and it gets mid 2.1s which feel slow as hell. Granted the TC gives the motor a bit more torque multiplication for the initial launch, I'd think a 6MT should be able to grab 2.1 60 foots with just a 3000-3500rpm clutch slip launch.

Sometimes I wish I could get past my disgust for the Asisn-built 6MT in the Z/G.

 

Stock flywheel, so no worries there. All this talk of 1/4 mile makes me think I should take the G to the strip next time. There's a pro drag strip at the same location as our test track, so it'd be easy enough to do. Hrm...

One thing I noticed on the track for the suspension test we did a few weeks ago is that the VLSD was overheating and losing its ability to transfer torque pretty quickly. That was disappointing, but I guess it gives me an excuse to upgrade the diff I'm thinking ATS or KAAZ clutch-type LSD, plus a Nismo diff housing to help it stay cool.

I quite like the 6MT. Sounds like it's not ideal for drag racing, but I like the short throws and precise feel to it. For the types of motorsports I tend to participate in with the G (autocross, time attack and lapping days), the gearing is just about perfect. Wouldn't mind a shorter final drive, but that'll hurt highway mileage so I think I'll probably just leave the gearing and FD alone.

 

While launching this car i have noticed that to get to 2.1 60ft, it can be done anywhere from 2500rpm to 4500rpm. Now launching at 2500 rpm u have to almost drop the clutch which gives u no control if the car bogs. To get very consistent launch i always keep my launching RPM above 3500 rpm and play with the clutch according how the car moves instead of hoping that it doesn't spin or bog. Past year i have been very consistent with my launches on the street and on the track. 5k rpm launch is a little too much but to get very consistent low 60ft times I know that clutch pedal has a lot more to do while launching at high rpm then launching at low rpm and hoping the car will take off the right way. Recently I had a Evo 9MR in the middle of the night at a stop light and the only way he can beat me is take launch. I raised the RPMs to 4k and we took off evenly and eventually he started falling back. after 1st gear. Street or not 4k is the sweet spot for this car with lots of clutch play. Did i mention im still on stock clutch at 63k.

 

What are the symptons when that happens?

 

I'd like to see what your car is running the 1/4 mile.

The VLSDs have always been rather weak and they're pretty much worn out by 40K to 60K miles, especially if you do a lot of racing. You should consider stepping up to a superior clutch-type LSD. Since you're an avid racer, you can handle the quick and sometimes aburpt engagement of a clutch LSD. The finned cover is always good insurance.

As for the gearing, I've played around with the calculations and I think for racing purposes (both drag and course), you might want to consider the 3.9 gears for your 6MT, especially with the Rev-up. The 3.7s aren't enough of a change, but the 3.9s might help a bit. However, you might have to relearn the car because of the extra torque multiplication and you might be in 4th where you were formerly in 3rd, etc which might not be a good thing. Definitely play with the numbers before considering a change.

 

Symptoms of the VLSD overheating include a delayed sensation of power being delivered to the rear wheels, somewhat like the way it feels when the clutch is slipping, but you also notice that the inside rear tire is more prone to spinning of slipping when the VLSD should be preventing this when it's functioning at its best. Viscous LSD's are definitely limited both in their torque transfer and their longevity (the fluid inside them, which you can't change out for fresh fluid, breaks down over time from repeated heat cycles and loses its thickening properties which give it its torque transferring ability). A clutch-type LSD will definitely transfer torque a lot more aggressively and won't fade the way a VLSD does, though there is a downside to clutch-type LSD's, namely that they can be noisy when making sharp turns at slow speed (chattering, like an aggressive tranmission clutch does) and the clutch material does wear out over time (but can be replaced). On the upside, clutch-type LSD's can be shimmed such that the aggressiveness with which they engage is adjusted, so you can really customize the setup of a clutch-type diff quite a bit if you want to.

 

^that makes a lot of sense. Even though i haven't noticed that at the track because i would do 5 laps most and the rest the car and the track was high speed the tightest turn was about 55mph and the fastest at 115 mph. In the canyons where there are lots of tight turns anywhere from 10mph to 40 mph switchbacks and 30 mph hairpins, I have noticed during a hard 15 minute hard drive the symptoms that u just described, especially at low speed corners. I always thought it was my tires but at the same time i was suspecting it was something else but did not know exactly what it was. That is why when u brought up VLSD losing its functionality during hard driving that came to my mind.

Thanks for the clear up.