you dont see very many folks running high hp manuals, its pretty expensive for parts after the 3-400hp range. that why i had went through the trouble of getting a custom th400 from a race shop. i am good for my 400hp crate engine plus one or two kits now for about 2000 with a custom converter, + combo manual/auto valve body. pricing manuals everything that would handle power adders was twice that at least and probably not as stout.

I completely agree with you. I build everything to run on the street fully first, then adapt it to as strong as or fast as I can on the strip. Only reasons for the top loader three speed is that it is an inherently strong transmission, Ford produced these specifically for GM between 1965 and somewhere around 1971 or 1972, so it is a bolt together proposition, and I wanted to have a manual on the street. The trans cost $100 because most on them were discarded for a 4 speed back in the days when they were available.
My plan is to drive the car with the 3 speed until I get the whole motor/car build all sorted out, then eventually change over to an automatic. The turbos will always work better with the auto as a manual will always be harder to operate to their fullest. You can't spool against a manual like you can a converter. Plus, with the converter you are minimizing the shock load to the chassis and the tires. So eventually I'll drop in a built something. A built TH400, or, if I can build it strong enough, a built 4L80E, both of which I have on hand to build. Being a street car first I would prefer the 4L80 for the overdrive. But for now the 3 speed is completely for fun.
The three speed versus a four speed is also a good choice because of the wide gear spread. The wider spread will work the turbos harder and let the torque work for you, plus it'* one less gear change for me to screw up, LOL.
I have my G8GT and I'm curious about the new 6L80 as an option. I'm wondering first, can it be built strong enough for the probable high cost to be reliable, and do the extra gears add any advantage or do the narrower gear spreads negate any advantage?
Anywho, long story short, I love a manual behind a turbo motor, but if it proves too costly for performance/parts costs (replacement clutches etc) then an auto will be built and dropped in, which I'm sure will be the case eventually.

Mark

i think you have so much power the 6 gears are not necessary. even in third with just my 350 i can power away from a stop pretty briskly. you have ton more power.

as far as the 4l80 i think its very similar to the 400 with an extra gear but you have to have the controllers and whatnot. so have to price doing the build and controllers vs just doing a th400 and a gear vendors. i believe they are both a .7, the gear vendors are what the real powerful street cars are running like on those street competitions were they have to run like 1500 miles and run at the track. like bob lutzes 57 chev is running 3000hp through it. they are pretty expensive though i try looking for them every so often, you dont find them used and new its like 2k. but it might still be cheaper than a 4l80 that can hold your HP. have to talk to a race shop by you see what they can do.

i love manuals, thats all i ever bought but i didnt build the car to drive like a grandma and i cant afford something like a tko that would actually last. its like 5 grand once you get all the adapters and crap

You can go full manual on the 4L80Es so you don't need a controller. My '73 TA was a Hughes TH400 full manual and I really liked it on the street. I would do that on the 4L80 too. You're right that the 4l80 is the same as a th400 but with an added planetary for the overdrive. Some parts interchange and the stock gear ratios are even the same. I've seen builds on the 4L80'* that will handle a lot of power but I've seen them fail at lower HP levels that TH400 could be built to handle too. So I hate to spend big bucks on the 4L80 and find out it can't hold up. I may have to go to a built TH400 to handle it. I just hate to have a non lock-up higher stall converter with the road speeds down here. Freeways are set for 75 MPH with normal sustained traffic speeds of 85 to 95 MPH. A TH400 and gear venders would be great but you would still have to contend with converter slippage.
Thank you for all your input though, it is much appreciated.

Mark

transmissions are all about the builder. i wore out the stock th400 in a couple months. and broke another but that was a bell housing failure. the last time i had it built by a race shop that does nothing but race transmissions. the custom converter is pretty good for around here, its auto if i want or manual depends how i shift it. so with 4.10s its going like 3000 at 55 which is what all the roads are here. if you want to cruise 75 or above going to need 320 to 350 and OD at least. if you do go electronic you may be able to get a lockup that handles the power, dont know thats where talking to them comes in.

It'* not just the builder, it'* what parts the builder uses and really comes down to what you can or will afford. A stock TH400, in good condition, can withstand a lot of abuse, and a modicum of power. Back in the day when it was quite an accomplishment to make 500 HP a stock th400 would last all day and take everything you threw at it. But as the HP increased and chassis and tire science improved (traction) the weaknesses of all transmissions were uncovered. As time went by the weaknesses were addressed and overcome. Now a TH400 can be built to withstand 3000 HP but boy, it'* gunna cost you. But it is doable.
Going full manual versus manual/automatic makes the trans a lot more responsive at the shift point. Takes away any mechanical mistakes and puts it on the driver. It also adds to the transmissions reliability, the solid crisp shift aids the clutches work and last longer. Even though it is in the gear you choose, it will not stall the motor like a manual if you forget to put in the clutch (come on admit it, we've all done that, LOL, if you've ever had a manual trans) .
Anywho, I am running a 3:50 gear to keep the turbos working so it would be fine on 55-60 MPH roads. But even our city freeways see 80-85 MPH just to keep up. If I just stayed on surface streets around the city it would not even be a topic of discussion. It would certainly be a lot cheaper. If I like the manual trans enough to keep one and the 3 speed works out, I would consider finding a GearVenders to adapt to it. I guess time will tell. (Or money will tell, LOL).


Mark

with 27inch tires and 1;1 third 3.50s calculate to 2396rpm at 55 and about 3000 at 70. its pretty high for cruising.

28inch 55mph-2310 70-2940rpm

My tires are 31 inches tall but still, even with the shorter 3.75 stroke I don't want that thing winding away just to go from point A to point B. I want to be using up it'* life expectancy at 25 pis boost and 1500 HP. LOL. Seriously, with the Arizona heat the higher the rpm the hotter the motor too. So, a good low cruise rpm is so much more beneficial all the way around. My first Pontiac was a '64 Catalina 2 dr post (sedan) car that was an ex-Police car. This was way back in '70. I dropped a '65 GTO 389 and Muncie four speed in it. Then I got a great deal on a 3:89 Pontiac posi center section so I installed that. It made that big ol' Cat really great off the line but it was revving high all the time. Kind of got unnerving fast. My '67 Nova had a 4:71 in a Ford 9 inch and that was always screaming.
Anyway, I would prefer an OD on whatever I eventually end up with. Or just relegate the car to local use and the drag strip, then build me a nice 3rd Gen TA with a milder turbo'd Pontiac for street fun and cruising. I've still got that 1962 Pontiac 4 cylinder to build. It would make a great 3rd Gen motor for street playing.

Mark

with 31s, the manual in 3rd, its still going to be 2036 at 55 and 2655 at 70, still pretty buzzy. the turbo would like 3.23 or so i would imagine and thats alot cheaper than any of the ODs.

as far as the turbo 4 i always thought a new 3.5 would be a good thirdgen engine. in my monte its got 242hp, 0-60 in 7.5, and get 32-36mpg. the fire bird is about 800lbs lighter and more areo dynamic.