Still stock l98 motor 6 speed with stock 3:08 gears 9 bolt Twin T-70 turbos went 12 flat at 122mph. Having a hard time building boost on the line with no 2 step just have to slip the clutch of the line.
New 355 AFR 210 motor almost complete finaly. I will also be going to a turbo 400 and maybe a GV over drive

 

Damn strong!

 

anyone run a GV with alot of HP, realy want that 4th gear for highway use.

 

That is a fast run. Nice job. Do you run into problems hitting the surge limit with such big turbos?

J

 

I am kinda a noob to all this but I don't see that being a good time at all . I am sure I am missing something but shouldn't you be doing a fair bit better ? Another gent on here has 1 smaller turbo T-62 and he is running 10's on the stock crank .

How much boost are ya runnnig ? Excuse my ...I wasn;t tryign to be a pric ....just trying to understand thats all

 

my motor is all stock I believe that guy has alloy heads/cam but not sure. I also run low boost 10 pounds. Huge turbos are not good at low boost especialy on a stock l98 motor. Remember ET is just a function of traction look at the speed 122mph thats not to far of from 10s.

 

ET is a lot more then “just a function of traction.”

122 is enough for an 11.1, but that disparity between et and mph suggests traction issues, drivetrain mismatch, tuning issues… basically, it’s making power but not in a useful range or not getting it to the ground. More then likely if whatever the issue is got taken care of it would probably be more like a 10.5@130 or so.

As far as big turbos/low boost… too big a turbo at low boost is much happier then too small a turbo at low boost, take a look at the shape of the compressor maps, a small turbo will fall right off the map and start pumping hot air, if not quit moving useful air altogether.

Either way, with the average f-body, to run 122mph you’ll need about 510 or so hp that would put you just inside the surge line on twin T70’s. Judging from the numbers I’m guessing that you were having problems spooling, problems hooking… and were making quite a bit more hp then that, so it’s quite likely that the turbo was actually in a fairly happy range.

As far as the TH400 + GV… well I considered it but just brought home a 4L80e last night… do you think I can get it into the tranny tunnel?

 

I think the turbos would be happier with a built motor nice heads etc. Yes with such big turbos a 2-step would of realy helped spool of the line like i said. My point was a single t-62 would work much better on a stock 350 then say twin t-70s. I mean if I bolted on a 106mm at low boost it would realy suck.
When I say et is a function of traction I mean that the car is geared and tired to leave the line and drive down the track like a drag car should. My car is very stiff road race setup and is not setup for its full potential at all, I just have to build things one step at a time.
I looked into a 4l80 from rossler that would hold 1200hp and he said 5 grand plus a converter so not realy sure I could go turbo 400/GV. What did you pay for your 4l80 I assume its built up to handle some serious HP? I should have the car finished for spring with a stout auto and a built motor and want to go 8.9 at 150 atleast thats my goal in the end.

 

It was relatively cheap… I picked up a known good one with 30K miles from a friend’s neighbor (my friend found it for him originally, so I have reasonable faith that it’s in good shape):


I’ll go through it myself, and even the stock parts are supposedly durable to somewhere in the 700hp range, (I’m not that worried about it since the formula should be a lot lighter then anything that anyone that is rating power ratings for one of these would expect it to be in). I’ll probably upgrade things as I see fit.

BTW, check out that 4.5” carbon fiber driveshaft out of the 1ton van that it came out of… I wonder if it's worth trying to get someone to try to shorten it.

For a sense of scale, that driveshaft is roughly 70" long, and that bed in the K1500 blazer is 6' long, and that's a 2" hitch ball laying in between them... what have I gotten myself into now?

 

Thats a damn good pick up if you can make it fit

 

if you get that th-400 with the GV overdrive to fit let us know because if my 700r-4 breaks for some reason next season thats the combo i wanna go with. That combo is probably as strong as a built powerglide but with lots more drivability and street manners

 

I've been looking at the 480le as an alternative to the 700R4. I think it will fit ok but still eager to hear what kind of luck you have. Don't you need a computer for that tranny?