FI GS4XX - Performance results question; a true mystery
03-23-10, 10:54 AM
#16
Rock, you gotta look at other things than just rear end ratio. Rear end ratio means nothing if you don't take into account the transmission itself. The IS350 has higher torque multiplcation in every single gear. It makes up for the deficit. In fact, they make both about the same amount of peak torque in 1st gear, but from there one out, the IS350 takes the slight lead.
Coupled that with a faster shifting transmission, slight weight advantage and maybe 16hp difference, you can see why the IS350 is quicker.
There is a spread of 8 years between the two cars. That's an eternity.
Coupled that with a faster shifting transmission, slight weight advantage and maybe 16hp difference, you can see why the IS350 is quicker.
There is a spread of 8 years between the two cars. That's an eternity.
I thought the notion of forced induction makes the car night and day. There was a member on here that ran a 13.9 sec 1/4 mile with his bolt-on GS4; similar to mine (maybe running at 270whp) and then on the other end of the spectrum you have members that have FI'd GS4's that barely can put down a 13.4 sec 1/4 mile runs with 100whp more! 100whp increase is NO JOKE and it only reduces the 1/4 mile times by .5 seconds? That's a terrible return from modding not to mention $10K later.
C'mon, aside from the IS350...just comparing the same car (any car) with FI and without FI should be almost a full second quicker in the 1/4 mile with a 100whp increase...assuming traction is achieved to the same degree as in stock form.
Last edited by Rock-a-Lex; 03-23-10 at 10:58 AM.
03-23-10, 11:16 AM
#17
Well at that power level, it's really limited by the transmission. Stock tranny can't handle more than 350whp without some sort of issue. Even with valve body upgrades, I don't know if it's going to shift quicker than the IS350's transmission. But with those kinds of power, I would rule out weight and aerodynamics since the GS would probably have more than enough power to overcome those small issues. I'm definitely leaning more towards the transmission's slow shift.
One interesting thing to note is that when I asked Pearlpower a while back about his former GS400, he said the car actually lagged down low due to the drag from the supercharger. It also reflects my friend's experience with another member's S/C GS400.
I haven't seen much from turbocharged GS400s so I can't comment on their track times. There are only a handful of them anyways.
One interesting thing to note is that when I asked Pearlpower a while back about his former GS400, he said the car actually lagged down low due to the drag from the supercharger. It also reflects my friend's experience with another member's S/C GS400.
I haven't seen much from turbocharged GS400s so I can't comment on their track times. There are only a handful of them anyways.
03-23-10, 11:44 AM
#18
Forum Administrator
iTrader: (2)
Stock vs stock has the exact same concerns as stock vs modified as far as impact of the weight differnece, taller gears, etc.
One of the things you're also running into here is a lack of information. There are a lot fewer FI 2GS4's and even fewer of them going to the track. Most of them are more for show or personal enjoyment vs performance trials and have heavy ICE and nice bodykits. I know I never took mine back to the track after I supercharged it.
If I WERE going to build a GS4 again for 1/4 performance fun, I'd probably look at lightening the car, traction improvements and steeper gears (perhaps a GS300 3.9 plus a TRD LSD) before FI.
One of the things you're also running into here is a lack of information. There are a lot fewer FI 2GS4's and even fewer of them going to the track. Most of them are more for show or personal enjoyment vs performance trials and have heavy ICE and nice bodykits. I know I never took mine back to the track after I supercharged it.
If I WERE going to build a GS4 again for 1/4 performance fun, I'd probably look at lightening the car, traction improvements and steeper gears (perhaps a GS300 3.9 plus a TRD LSD) before FI.
03-23-10, 12:55 PM
#21
Instructor
I know there are manual 2GS now, but I think most of them are NA-T or GTE. I don't recall too many stock V8s with a 5 or 6 speed. I think that would make a pretty good testing platform. I know that when Rod Millen did the IS430, obviously a lighter chassis, but with the Getrag mounted up to it, it put a lot more power down then the A650e in the GS on the dyno. I don't remember them putting the IS430 on a dyno, but they did dyno the GS430 right before they pulled the motor. Regardless, we understand what a stock 400 or 430 can do, we need to get an idea of what a manual might might in a 1/4 mile. I know we are comparing it to an IS350, but that is far newer technology, I can't believe the GS460 is making the same power that the IS350 is. That being said, I think it's the transmission and weight, because the UZ platform is a great performer.
03-23-10, 01:02 PM
#22
Here is the IS430 dyno sheet. I think all it has for mods is an intake headers since the stock 3uz manifold couldn't clear the inside of the engine bay:
For those who can't see, it's 283whp and 283ftlbs.
We know with headers and intake on most GS4/SC4 will gain about 20whp over stock. This car made about 40-45whp more than stock so perhaps 20whp is recovered with the V160 over the stock auto.
For those who can't see, it's 283whp and 283ftlbs.
We know with headers and intake on most GS4/SC4 will gain about 20whp over stock. This car made about 40-45whp more than stock so perhaps 20whp is recovered with the V160 over the stock auto.
03-23-10, 01:21 PM
#23
Forum Administrator
iTrader: (2)
Another point of interest.... take a look at the 2006 3rd gen GS430 which HAS the six speed and the 4.3 liter v8, but the weight and gearing are more in line with the 2GS.
Quarter mile times for bone stock are 14.1 (best I've seen) - 14.5.
Example: http://www.motortrend.com/roadtests/...ecs_price.html
Interestingly, the RMM IS430 had a 14.0 time here
http://www.modified.com/features/041...430/index.html
Quarter mile times for bone stock are 14.1 (best I've seen) - 14.5.
Example: http://www.motortrend.com/roadtests/...ecs_price.html
Interestingly, the RMM IS430 had a 14.0 time here
http://www.modified.com/features/041...430/index.html
03-23-10, 01:37 PM
#24
Another point of interest.... take a look at the 2006 3rd gen GS430 which HAS the six speed and the 4.3 liter v8, but the weight and gearing are more in line with the 2GS.
Quarter mile times for bone stock are 14.1 (best I've seen) - 14.5.
Example: http://www.motortrend.com/roadtests/...ecs_price.html
Interestingly, the RMM IS430 had a 14.0 time here
http://www.modified.com/features/041...430/index.html
Quarter mile times for bone stock are 14.1 (best I've seen) - 14.5.
Example: http://www.motortrend.com/roadtests/...ecs_price.html
Interestingly, the RMM IS430 had a 14.0 time here
http://www.modified.com/features/041...430/index.html
Wow! Very interesting that a 300+hp car (first gen IS with the 4.3L engine) weighing only 3200lbs couldn't break into the 13's in the 1/4 mile. What was going on there? Tranny and gearing perhaps?
03-23-10, 01:56 PM
#26
Perhaps the mags do not really wring out the power when they test the cars...who knows?
03-23-10, 04:27 PM
#27
Well, in all fairness when the various magazines initially "tested" the IS350 they were getting 13.8 sec 1/4 mile times. Now, there are everyday people squeezing out 13.2-13.5 range in the 1/4 mile. This is what I truly find odd. Perhaps the mags do not really wring out the power when they test the cars...who knows?
Perhaps the mags do not really wring out the power when they test the cars...who knows?
03-24-10, 08:25 AM
#29
One thing we are also ignoring is the difference in all these tracks people are running on. Luckily, one thing living in East TN provides are tracks every 40-50 miles. I am not sure how many of you follow drag racing, but Bristol's Thunder Valley is about 45 minutes away. There are also many lesser known tracks that their track prep is sketchy at best. The difference in a well prepped track and one that is not can be huge with RWD cars. Since my VR-4 is AWD, it has never been a huge issue for me. However, I have friends with high HP Supras lose a full second or more from running one track to the next. We cannot just compare 1/4 miles times across the board because you are not comparing apples to apples.
Rock-a-lex, All I can add is don't pay too much attention to the forums and the claimed 1/4 mile times for this very reason. All you're getting is the claimed time, which may or may not be true.
What you're not getting, is temperature, humidity, track conditions, etc... Hell, even two bone-stock GS4's running the quarter might have a half second difference. Once you start talking about the added factors of modding, you don't stand a chance to compare any apples-to-apples.
So as with most things, I don't think you can pinpoint the transmission, weight, tire choice, or religion as the primary culprit. In truth, it's probably 100 different factors all conspiring against ya. But you already know all this...
That said, i'm not trying to discourage your constant efforts to wring every .1 outta your GS, cuz I got alotta respect for your contributions here. Keep it up bro
