Yes, more complex. I get about 16 mpg in a roughly 12-flat car at sea level. and with my converter I'd cook the trans without lockup. I've driven my car from MT, to ID, to WA and back. Would have been rough with the 3.73's, that's for sure. Especially at 75-80 mph that we drive alot out west here. It's nice to hear yourself think on the highway; with the TH400 in there before it wasn't fun driving 60 miles. Will it pay for itself? No. bUT like you said, using financial analysis would have us driving Chevys (at least engines) in the first place. Jim, do you have to cut the floor to get a GV in a 70 GS? If it would be a simple fit, I would say that it is is a good option. But the gear spread still isn't as good without a low gear-set for the TH400 if performance and highway driving is on your agenda. If you're just racing, then, like you said, why an o/d at all? I agree, for a cruise around town and go to the races car, the TH400 is perfect, with a SP if it fits the cam selection. Forget the o/d and buy a set of heads with the money. Where do I get a good, true 9" 4000 RPM switch-pitch? I can't bash the TH400, it's all I ever used before my first 2004r. A GV makes it even better if weight and fitment can be accomodated. I was going to put a TH400 with a BW o/d unit in my Skylark, but it would have cut the trans tunnel all up for it to fit. and yeah, I dunno if a 2004r will live behind a stage 2. Cool factor: I'a amazed at the people that think the SP is some kind of high-tech miracle. Cool would be a blown stage 2, of course with a TH400 behind it! (I coulda paid for the blower setup with the money spent on the trans & converter ou: )
Adam, Can't speak from experience yet on the GV install, as the first car one is going in here had to have the quarters replaced unexpectedly, so it has not happened yet. I was assured by the folks at GV, that the most it will take is a little "clearancing" of the floor boards, but it is very minor. And since I am sure a few of these things have found their way into BB Chevelles, which use the same length 400, mounted in same position, on the same frame, with the same floorboards, they should know. I will post a bunch of pics of the install, when that happens here, in about a month or so. Car got the LH quarter welded today, so it should be in paint soon, and then we can install the drivetrain. 4000 rpm 12" VP converter? No such thing as an efficient one.. 3200, behind a powerful big block, in a heavy car, that hooks hard, is about all your gonna get. Do you really need a 4000 rpm converter? Could you live with less cam duration? Remember, better heads makes the motor think it has more cam in it. I have built a couple 625 Hp Stage 2 464's, and they had 260/266* cams in them, and are quite happy with a good efficient 3500 stall converter, for light street/ strip action. What your dealing with is the age-old problem of wanting your cake, and eating it too. No real easy solution to that. - Car trailer and a pickup come to mind.. As far as the gear spread issue.. it's commonly accepted among drag racers, that the 2.75 low in a 400 won't really get you anything on the track. Simply because a fast car is really not in low all that long, to make enough of a difference. Your generally better off raising the rear end ratio, to get the multiplication in low gear that you want, then using the OD to be able to live with it. And 2nd od ratio in a 400, could be worth more on the strip than you might think. The transition from 2nd to high in a 400, although only .48 of a gear ratio change, happens right when the aerodynamic drag really starts to become a factor. We thought that with the Buick torque, a set of 4.10's would be enough for the Tube car, but you would be amazed at how much the tach slows down, when that car hit's high gear, at about 80 mph. It's in high for the majority of the run, and we need more gear to make it go faster.. even if it gets the trap rpm a little farther beyond the motors peak HP rpm. So pass the $450 lightened big pinion 9" Ford Pro gears.. in a 4.30 ratio. I had one very well respected Buick racer tell me that when he went from 4.30 to 4.10, and was running 9.80's, it dropped his car right back into the 10's. ON the street, I have yet to see a car as powerful as yours, do anything but go sideways in a cloud of smoke in low gear, even with "only" a 2.48 low. JW
question, thoughts, ramblings.. Jim, I hear ya screaming... maybe its just wishful thinking on some of our parts, the od tranny working behind a hot street/strip Buick 455. Wanting more gears, lower cruising rpm's, better fuel economy, and still having better accelleration of higher-numerically gears? Especially from transmissions that were never designed for anywhere near that kind of torque. Why not just stick with the old tried and true, and consider ourselves lucky that we have the ONE part available to us that will live. But like I stated earlier, 20+ years ago people were laughed at for dreaming of using a lighter-weight and less hp-robbing T350 or PG behind a high-torque high-hp Big Block. They said you're crazy, it'll break and stuff like that. Those people that were laughed at, some of them probably went on to develop parts that would help these "weak" trannys stay ALIVE! Nowadays, I've seen SEVERAL T350's behind BBB live for years in a strip-only or HOT-Street application. Yep, sometimes they break. Such is life. Maybe that part that failed can still be improved on. And because of that failure being identified, it eventually will. Please don't misunderstand me, I think that GV over/under drive units are the neatest thing since sliced bread! I've drooled over them since I first heard about them. Personally though I decided that it was too much money for me. I know a couple a people that use them. One of my customers likes BBO 455's and has 2 of the GV OD units, T400, BBO 455 combos; one in a 65 Suburban and one in an old cube van!!:jd: :shock: He's 73 y.o. and he says that with these GV OD's, they have enabled him to go WAAY over a 100mph! ( Is this what happens to old hot-rodders? Eccentric, senile AND STILL building hot-rods? ou: ) I also wanted a modern 4-speed auto OD every since GM first came out with one. I've thought many times about getting an adapter plate, or cutting the bellhousing off and getting a JW bellhousing and using a 700 or better yet, 4L80E. I've spent a lot of $ on my rearend, gears, exhaust system, and most importantly the T350 I use now. Its an extremely tough situation that I put myself into, deciding how best to reduce rpms. Both ways have their pros and cons. Too many to list.. I've come to the conclusion (for now) that I can't afford either, which means I can't just drive anywhere I want to go. I want to go with the 4-sp od tranny, but until my other tranny breaks, I can't justify the cost of replacing it. I really hate wasting my $500+ converter also, which would need to be changed to an even more expensive lock-up. Which brings me back to the GV, and keep my existing equipment. ou: Vicious circle, HUH!? Any chance of getting these GV's to fit under a stock floorpan, or fitting a 3" X-pipe system around them? Thanks for letting me ramble on..:grin:
Notice I said 9" SP converter; OK a 10" would be better. Well, maybe someday.... yeah, but better heads and more cam means...:laugh: That's good for me to know when the engine comes out. Maybe just the tighter converter would help hook better out of the hole? YES!!!!, and it's gettin' damn expensive! I have the trailer, and it's either sell my little pickup for next to nothing and buy a mega-dollar new one, or...,or,,, but none of the option sounds real good. Unfortunately a Duramax probably isn't in my near future. Besides, then I wouldn't have a streetcar like Garrison does. That's something I wouldn't have known... Yeah, and Hoosier QT's suck on the highway, o/d or not! o No: :laugh:
Yeah, hmmmm.... OD or good ported Aluminum heads? ... no brainer for some of you I guess. I would like to 'road-trip' the car though. It only came outta the garage about a half dozen times all year and twice was to a track. Trust me - cruising downtown Elko leaves a LOT to the imagination... Adam knows. At least I'll have a stout 12-bolt now so I can strap on some sticky tires. And BTW Adam, Bruce strongly recommends I stay with 3.55 instead of 3.73. This stuff drives me CRAZY! o No:
Yeah? he told me I have too much converter for a street driver. It's right at the torque peak though if you look at JW's dyno sheet for the hemi-killer cam. I'd probably tighten it up a bit if I did it again though. 1st gear is useless without stickies. He's probably right with your cam, the extra gear wouldn't make you any faster. You know, with you having a good TH400 and an engine suitable for a good SP converter, you may be a perfect example to fit JW's TH400 on-the-brain ailment. :laugh: It would be cheaper than a good 2004r and you'd have all the benefits discussed above. GV is priced out at $2195 I think on their website. Besides, you didn't have enough to consider up 'til now. Between operating the converter and o/d switches you'd be busier than a shuttle pilot on takeoff.
...which is how I got beat in the brackets at Vegas. Line-lock, switch-pitch... and I was sleepy from too much partying.. cut a 1.3s light, you read it right, 1.3s and ran a 12.61 on my 12.62 dial. Had I cut a mediocre light ole Dave would have had to stay in it intead of backing into me and probably would have broken out bigger than I. I hear they had to change the green bulb after each of my runs..:eek2:
:error: :shock: :sleep: :sleep: :sleep: :spank: :spank: ou: :laugh: :laugh: Drink some GOOD STRONG coffee before the races, like we do up here in Seattle!:Smarty: My reaction times usually averaged between .009 and .020. :Brow: Just kiddin' around with ya , but DAMN! That's some serious snoozin!!:laugh:
