VegasZ35TH just wait for superchargers to become compatible with the 300hp engine - they're working on it or at least vortech is

 

You are right, there are a few (including Vortech) that are working on them. I have been waiting for them ever since I got my 35th however instead of just running around stock I decided to go NA route for now until an SC does become available for the 300hp. I know I am throwing down a lot of $$$ by doing this but I don't have a problem with it. So far I have really enjoyed all of the bolt-ons that I have done to my Z.

 

I love my gears one of the best mods ive done since then...
help cure my low end low speed problems of the rev up motor... i think that the FI would take car of the top end...

 

All this non-sense about shifting... If you have the 3.3, 3.5, or the 3.9 you will have to shift through 5 gears to get through the 1/4. Plus if you street race how many times have you read a post in this section about races from a dig? 10% if your lucky... Most race are from a roll and up to around 125mph, and the advantage would be to have the 3.9 gears in this situation, right? I may be wrong but as someone stated earlier shorter gears = faster acceleration. Plus I hit peak whp around 5800rpm's and it slightly drops off, so I shift at redline because the car is still making good numbers to 6600rpm's. Then when I shift I am at a higher rpm than if my car had 3.5 or 3.3 gears which would result in a higher whp into the next gear. Last thing is what about having a Z with 500+whp, don't you think their traction issues are worse than a Z with 400whp so are you saying don't increase your whp because you will have traction issues? The 3.9's in my car are not as bad as everyone makes them out to be... at 400whp we all will have traction problems in first and yes it is more so with the 3.9's but my car grabs great in second with some slight wheel spin but it quickly grips and goes. Everyone has preferences but I bet with 3.9's and some DR's - same car, same driver - the 1/4 times would be better than a Z with the 3.5 or 3.3 gears.

 

Take your car to the 1/4 mi and run it. Let us know how it goes.

 

All y'all Tampa Turbonetics guys should go together! That would be tight as hell. I'll go and run some NA with y'all...when the car gets out the shop

 

here are the results i found from jpc250z and his vortech s/c.

Best 1/4 Mile Time (With 3.12 Pulley)

R/T --- .935
60' --- 2.033
330 --- 5.618
1/8 --- 8.584
MPH --- 83.95
1/4 --- 13.180
MPH --- 106.16

Best 1/4 Mile Time (With 3.12 Pulley and 3.5 Rear End)

R/T --- .754
60' --- 2.039
330 --- 5.503
1/8 --- 8.320
MPH --- 88.13
1/4 --- 12.851
MPH --- 108.56

i only can imagine it would get even better.

 

I hope to go soon before it gets to hot out.

 

just by looking at those times, he gained 5mph in the 1/8 but it tapered down to only a 2mph difference in trap in the 1/4. And I think that has to do with the fact that he spends less time in each gear before shifting.

And this would only be more exaggerated by something like a single turbo Z where all the torque is in the midrange and will just cause you to spin through 3rd as well as 1st and 2nd, where with the 3.5 you mainly spin through 1st and a little bit of 2nd

 

i would agree with this, but, the 60 foot times arnt that off, and to that means he wasnt really spinning anymore/less. the advantage did become small (mph) but the et was still considerably quicker. this is opinion based, but if it was me, 3.9 and a turbo with some nice tires would be in my cards.....

his 1/8 was .2 tenths faster, but his 1/4 was .3. the gearing does not give more hp actually, which is the biggest factor in trap. but, the gearing advantage seemed to allow the motor with exsisting hp get the car to the 1320 .3 faster. pretty damn good if you ask me.

 

I don't know about you, but I had 2 different runs at the latest track day with near identical 60' times and my ET was .25 or so different between the two.....so consistency is a big factor as well.

 

My car has some light wheel slip in second but never in third... occasionally I will get a chirp, but only less than a handful of times when I am under WOT. Like I said it's not as bad as it's made out to be.

 

I'm sure somebody in this forum already proved this. With a supercharger your better off getting the 3.9, because you get to your max boost quicker, and you can keep it there by shifting. In a turbo, your boost comes a lot sooner, so you want to keep it in boost for as long as possible, hence you would go for the 3.3.

 

really you don't want the car to stay "in boost" longer, you want it to stay where the power is - which is hp towards redline

hp is a function of tq vs speed (rpm)

a turbo has bigger tq in the midrange, but makes more power (hp) towards redline because of the increased rpms.


like if you are a punching bag and a big guy decks you hard 50 times vs a small guy who jabs you 200 times 4x faster. Both guys create the same amount of total work on the punching bag. When the big guy hits you hard though you FEEL it, where the small fast guy jabbing you isn't as eventful in terms of getting bruised

tq is cool cause you can really feel it cause the engine has so much response. Just by flooring the pedal, you get such a wide range of power. Where at redline if you floor it there isn't as much of a difference because the tq has leveled off and there just isn't as much difference between 6500 rpms and 6200 rpms in terms of feeling thrown back in your seat so the rpm difference has leveled off too.



changing final drives actually has NOTHING to do with what rpm you land in at redline. That has to do with the gear ratios in the transmission

If you shift at redline you will end up at these rpms:

2nd gear 4042
3rd gear 4612
4th gear 5165
5th gear 5192
6th gear 5240


as you can see, the Z's gearing puts you closer and closer to redline each time you shift into the next gear compared to the last gear you were in. That's very aggressive gearing. A car like a C6 corvette starts losing rpms in 5th and 6th gear and so those gears will feel really weak, where the Z's will feel good.

"staying in boost" kinda applies to a FI Z, but not in the same way as a honda civic @ 30 psi would because the Z's power curve is so relatively flat compared to those smaller engines. Small engines with lots of boost are nothing without their boost. The Z's engine is pretty strong even without boost. Either way the rpms in each. What the final drives do is slow down or speed up your accelleration from that rpm to redline.

 

it also depends on the size tire that you are running. if you are running a taller tire than factory your gear ration will go numericaly down. if you run a smaller tire the number will go up.

 

I had similar results changing gears in my v6 camaro. with the stock rear (3.23) I was getting 2.4 60' and running the 1/4 in16.5 @ 85mph. Then I changed the rear to 3.73 gears. 60' became a 2.0 and the 1/4 was 16.1 @ 82mph. I was quicker in the 1/4 but my trap went down 3mph. I noticed this with most f-bodys and would assume the Z would respond in a similar fashion of reduced et and trap speed

 

the vq is basically a top end motor so i think that the trap should be better. ie the vq runs up to 7100 and the v6 camaro goes to around 5500

 

I'm figuring that the 3.9 gears would be bad for gears 1-3 on a ST/TT or stillen roots SC and good for 4-6th gears

On a vortech or ATI, I think the 3.9 would be good for all the gears.

 

Sentry your rpm's for shifting at redline are wrong, I was well above 4000rpm's on a 1-2 shift @ redline stock. WItha 7100rpm limiter I could land 5200rpm's all day long....

 

I was talking about 6600rpms

1st Gear Ratio: 3.794:1
2nd Gear Ratio: 2.324:1
3rd Gear Ratio: 1.624:1
4th Gear Ratio: 1.271:1
5th Gear Ratio: 1.000:1
6th Gear Ratio: 0.794:1


so shifting at 6600 rpms at first gear = 2.324/3.794 = .612546

.612546 x 6600rpm = 4042 rpm

is that wrong? I dunno, I'd try it myself to verify it or not, but my car is in the shop

I'm thinking in the higher gears it'd be past 5000 rpms

maybe if you don't lift the gas to shift or if you shift at 7100 rpms?