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-   -   Th350 and 12 bolt gear help (https://67-72chevytrucks.com/vboard/showthread.php?t=743552)

Techx 07-30-2017 10:21 AM

Th350 and 12 bolt gear help
 
I just dropped in a blueprint crate 355 with a eddelbrock 1806. I currently have a th350 with my best estimate on my gears being 1st:2.52 2nd;2.00 3rd: 1.00 with a 12bolt 3.08
I'm running 9.34_9.48 sec for 0-60mph with a 17.2 1/4mile. I would like to get down to 10sec on 1/4mile and still drive 80 on highway for a long 6-8 hour trip twice a year. Is there anyone with experience on doing something similar out there?

Thanks

Techx 07-30-2017 11:26 AM

Re: Th350 and 12 bolt gear help
 
Ok then let's go with the best 1/4mile I can get while being able to do 80 a handful times a.hear on the highway. I m needing guidance guys. I'm basically been doing this self taught with local mechanics taking over when I run into a major issue.

hjewell2 07-30-2017 12:14 PM

Re: Th350 and 12 bolt gear help
 
Well lets forget about running tens for a moment.

A nice cruiser by day and tens by night is almost impossible with the weight we are pushing with these trucks. so lets stick with Cruise. A 355 gear positraction rear will give you the best of both for good performance and highway cruise.
stock converter and small cam but still have fun.

mikecaddy500 07-30-2017 12:22 PM

Re: Th350 and 12 bolt gear help
 
You will need a four speed automatic Or better and maybe a small shot of nitrous for the strip.

Coley 07-30-2017 12:33 PM

Re: Th350 and 12 bolt gear help
 
...are you involved in racing/competition with this truck?....is that where the performance requirement comes from?
....Personally, I'm not even sure if 'the farm truck' is running a 10 second quarter mile...and that truck is fully loaded and prepped for bear with a very nasty big block.

All good
Coley

AussieinNC 07-30-2017 12:42 PM

Re: Th350 and 12 bolt gear help
 
Speed costs money...How fast do you want to go?

Your truck, assuming it is steel bodied and a long bed, weighs in the vicinity of 4000 pounds.

To get that amount of LEAD into the tens will take approx 750 HP....great traction and a specialty trans and rear gear.

Check out this link to an online calculator..

http://www.etcracingprograms.com/etcalc.htm

You have a choice...nice cruiser and tow vehicle...add a 4L60e trans and controller...

or build a race truck...get that weight down to around 2000 pounds and you only need 400 HP to get down to 10's...you would still need a beefier trans than a 350...think race prepped 400... and a stouter rear end...

:chevy::chevy::chevy:

Techx 07-30-2017 01:09 PM

Re: Th350 and 12 bolt gear help
 
Just want a sleeper for my own entertainment.

Mike C 07-30-2017 06:51 PM

Re: Th350 and 12 bolt gear help
 
TH200 4R and a set of 4.10 gears would be a nice setup. Should have you in the low 15's high 14's and be able to cruise anywhere. Built TH200 4R and built 700R4 are about the same $, but I MUCH prefer the gear split on the 200 and it is a bolt in for the TH350 if you just slide the crossmember back. Uses same driveshaft. I have an Extreme Automatic TH200 4R on order to put behind my (factory rated...) 390hp 427 L36 with 2400 rpm converter.

AussieinNC is more realistic with his 750 hp at the crank estimate.

FWIW, it takes about 550 whp to get 4000# into the HIGH 10's. And you are probably putting down 220-240 whp at best. Your idea to just improve what you have is good. But it won't be 10's.

ElKotze 07-30-2017 07:26 PM

Re: Th350 and 12 bolt gear help
 
A buddy of mine is drag racing his truck and he is actually driving it to the drags, no trailer. LS-engine with turbo, built OD trans and rear end among other mods like ecu and custom fuel system. It's running 10's. Just to give you an idea.

ElKotze 07-30-2017 07:32 PM

Re: Th350 and 12 bolt gear help
 
1 Attachment(s)
:chevy:

harpo231 07-30-2017 07:34 PM

Re: Th350 and 12 bolt gear help
 
8th mile ? How much LS ?

harpo231 07-30-2017 07:35 PM

Re: Th350 and 12 bolt gear help
 
oops too slow

ElKotze 07-30-2017 07:52 PM

Re: Th350 and 12 bolt gear help
 
Just a good ole 5.3
10# boost, 4220 race weight, 10 bolt with 3:73 with Yukon dura-grip posi and Proform girdle, Trickflow 216/220 .560/.560 114 cam, 11.4 AFR

AussieinNC 07-30-2017 08:01 PM

Re: Th350 and 12 bolt gear help
 
10.5 and 127 mph equates to a 530 HP LS, assuming 3200 lb truck...

Sounds like a sweet combo....

Wondering if that "special fuel system" is code for NOS....

:chevy::chevy::chevy:

ElKotze 07-30-2017 08:04 PM

Re: Th350 and 12 bolt gear help
 
Nope, no NOS, Walpro 450 intank, corvette reg/fuel filter, 80# injectors (@98%....LOL).

AussieinNC 07-30-2017 08:06 PM

Re: Th350 and 12 bolt gear help
 
@98% is really cutting it close with a turbo...might be time for bigger nozzles...

ElKotze 07-30-2017 08:11 PM

Re: Th350 and 12 bolt gear help
 
True, we were just surprised how well everything worked out. Keep in mind, you can cruise that rig down the Highway for hours without any problems.

biketopia 07-31-2017 02:18 PM

Re: Th350 and 12 bolt gear help
 
Quote:

Originally Posted by ElKotze (Post 8003803)
A buddy of mine is drag racing his truck and he is actually driving it to the drags, no trailer. LS-engine with turbo, built OD trans and rear end among other mods like ecu and custom fuel system. It's running 10's. Just to give you an idea.

ahhh the magic of forced induction and modern engines. But another comparison, my brothers big block Pontiac wagon weighs about 3600ish I think, ford 9"3.55 gear, th400, built 496, 28" slick runs 11.66 at 116. We drive it 200 miles each way twice a year to cruisen OC, but it's most comfortable about 70mph on the highway. 11 second street car is FAST. Besides, faster than 11.5 you need a cage...

ElKotze 07-31-2017 07:02 PM

Re: Th350 and 12 bolt gear help
 
Sweet, I love the sight of a wagon going down the drag strip !! And yes, everything under 12 seconds is FAST and doesn't come without a lot of work to the entire vehicle.
Talking about wagons, I was trying to talk my wife into getting an AUDI RS6. It's a wagon, but she didn't bite.....;) Now I might just build a hot '68-'72 'burb, looks better, too.


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