Corvette ZR1

[ogg vorbis]

don't misunderstand me. i'm NOT saying 638 bhp is 'bad'. my point is, if the ls9 is the last high hp v8 from gm, they should have squeezed as much out of it as possible.

they should have tested a kb 2.4 with the 2300. the 2.4 makes 525 whp with 7 psig and 10.5:1 compression (LS6). the 2300 makes 550 whp with 10.5 psig with 9.1:1 compression (LS3). 3.5 psig is a BIG difference for 25 whp. considering the LS3 is 8.8% larger, and has much better flowing heads, the tvs falls short - if only a little. a 10.5:1 motor will get better mileage than a 9.1:1 motor, and not have any lag. with a s/c you have to fuel 700 hp to get 638 hp.

a 2.8 high pressure may be less efficient than the 2300 on a certain motor for two reasons: it's not ideally suited for the motor at low rpm (more for high rpm power), and if it was a high pressure unit, it's self explanatory. you didn't mention the motor displacement, as this will affect the resultant power band, and efficiency. just like turbos, s/c need to be matched to the motors (size, ve, cam, etc).

kb DO have recirculation valves, just like tvs, so they do get good cruise mileage. it's that gawdy (imo, it could be better integrated) tube alongside the s/c body. go through kenne bell's site: http://www.kennebell.net/techinfo/techinfo-general.htm

manufacturers are limited by emissions, warranties, etc. as a consumer, i want a product that's easily modded. i do believe the tvs is good to 700+ whp. maybe a handful of people will want 950 whp, and the point is they won't get there with the tvs, and it's impossible to bolt on a different s/c.

i've always wanted a turbo zr1. modern turbos have NO parasitic loss, they make more hp at the same boost than s/c, there's no lag (ball bearing turbos or borg warner ETT), replacement turbos are bolt-on (if you can't just turn up boost), they maintain boost through gear changes, and increase fuel economy. the pcm can control boost level at all rpm - you can put the power anywhere you want. s/c can only dream of that kind of flexibility. lag in a manual is moot anyway, since you can let out the clutch anywhere - and it's only an issue from a dead stop. and automatics can use looser torque converters that lock up during acceleration. an ls3 dynos at 394 whp. 10.0:1 compression lowers that 3% to 382 whp. adding a turbo with 7 psi boosts that 48% to 565 whp. more power, 2-3 better highway mpg.

[ogg vorbis]

Originally Posted by epaulo

i see i see, whats the FDR on the GTR?

fdr is 3.70:1. tranny is 4.06/2.30/1.59/1.25/1.00/0.80. stats from may 2008 road & track.

assume the LS9 makes 430 hp before adding the supercharger. a turbo would need 7 psi to reach 638 hp. 10.5 psi would make 737 hp. ergo, the supercharger is eating nearly 100 hp! you still add the same amount of fuel whether you make 737 hp with a turbo, or 638 hp with the tvs. at 7 psi a turbo can do without an intercooler, or use 10:1 compression for great mileage...a couple more than the tvs. i think it's reasonable to expect 20/30 mpg with the turbo.

i like that the peak hp rpm is 6500. let's see the LS8 better that.

[SRSS]

turbo charging is your best bet for building power because it dosent take power to make power and with new turbo charging technologies there is no lag!!

[redTT]

Originally Posted by SRSS

turbo charging is your best bet for building power because it dosent take power to make power and with new turbo charging technologies there is no lag!!

And with the new supercharging technology the effeciency is closer to that of a turbo without the need for extra plumbing, more weight over the front, or the other annoying stuff associated with turbocharging.

BTW turbo charging still has plenty of lag as compared with supercharging and the power delivery in supercharging is still allot more linear.

GM did look at using turbos for the ZR1 but found them lacking in the durability stakes.

[redTT]

Nissan GTR and Porsche Turbo

[ogg vorbis]

Originally Posted by redTT

And with the new supercharging technology the effeciency is closer to that of a turbo without the need for extra plumbing, more weight over the front, or the other annoying stuff associated with turbocharging.

BTW turbo charging still has plenty of lag as compared with supercharging and the power delivery in supercharging is still allot more linear.

GM did look at using turbos for the ZR1 but found them lacking in the durability stakes.

putting an air-to-water intercooler in the intake valley - like the s/c - gets rid of all that plumbing. did you know a supercharger kit weighs 140 lb? it's no lightweight. i expect two turbos to be quite a bit lighter. they're also not on TOP of the engine, where it has the worst effect on centre of gravity.

ball bearing turbos on a large v8 sized for 700 hp (not overly big) won't have lag. being able to tailor the torque curve is unique to turbos.

as far as durability, now turbos have ball bearings, water cooled centres, inconel turbines, large shafts, blow off valves, ceramic coatings. they may have particular maintenance, but with the proper care they're just as reliable as anything. i'd expect a top-of-the-line turbo for a corvette. imho turbos have way more pros than cons, and gm had some other priorities that put the s/c ahead.

[firefighter]

With an ENGINEER at the wheel, lets get a Real Driver and see.

http://www.autoweek.com/apps/pbcs.dl...760145638/1065


That is all.

[E. Haskell]

Originally Posted by firefighter

With an ENGINEER at the wheel, lets get a Real Driver and see.

http://www.autoweek.com/apps/pbcs.dl...760145638/1065


That is all.

I agree.

I believe Nissan spent months testing and tweaking at the 'Ring and they paid a former Formula 1 driver (Toshio Suzuki) to help develope and drive the GTR. From what I've read, no one has more experience on the 'Ring than Suzuki.

GM took two weeks, let an engineer drive (who admitted he could've gone faster) and didn't have great conditions.

Maybe GM is planning to do what Nissan did - release a time and then come back with another time in better conditions that is 5+ seconds faster.

[firefighter]

Here is more of the same.

http://blog.gmnext.com/?p=194

Also many feel the GT-R used was closer to what we can expect from the Spec V.