SBC 377 w/6:71.

[George]

Hello Spud. I have changed my combo from injected to blown and so far have kept the gearing the same. I know I have gone from a 650hp 355 to a 800hp + 377. We put 5 runs on it last weekend and it ran a best 1/8 mile et of 4.76 and best mph was 156. I am running a PG with a 1.80 Low gear a new 9" 6200 stall convertor and a 4.86 gear ( Mopar 8.75 742). I would like to leave the 4.86 in it as it is a 9310 build and anything else is new street gear stuff. I ran a 12 X 31 tire and also have a set of 12 X 33s. My problem is the car is too aggressive at the hit and so far tire pressure and wheelie bar height adjustments haven't helped much. I am running a 1 to 1 pulley ratio and am seeing 12-15 psi on a memory gauge setup. A 4.60 et is where I want to be. I will be running 1/8 mile only.

Maybe my question is: what does a alky blower want? RPM as high as safely possible or something to load it harder ?

After I get this figured out I will be addressing cold cylinders . Convertor helper? Thanks so much > George

[Spud Miller]

Hi George, those gears, with the 1.80 low and high stall are combining for a very violent leave. Any one of those changed would improve things. Different gears would be least expensive. The blower is making a bunch of new torque. More torque means you don't need all that gear. I also think the stall is too high... It's definitely above peak torque I think. 5000 would be better in my opinion.   Spud

[dreracecar]

377 , 3.90gear 33" x 12" 18%over, 10" converter leave off idle on the hand brake

1.11 60' 4.55 1/8 @153.77mph

[George]

I am running a 2 step and have been leaving at 5200-5600. I doubt turning that back will help. I have a 4.30 gear set. Running the numbers the 4.30 should drop rpm by 1000 but will it be enough to calm it down?

Will I see much difference in 60' going from a 31" to a 33" tire?

Thanks again. George

[dreracecar]

Change to the 4.30 and the 33" and play with launch rpm till everthing is happy, dont worry about top end speed and et yet , that will come later by adding boost. You did not mention if this is an index or all out class you are racing

[George]

It's a dial in class. Just has to be 4.99 or quicker.

[dreracecar]

So then , soften the gear and go with the taller tire, 60ft does not mean crap as long as its consistent, and throw some blower at it till the et is where you want it. Make laps and log all info like track condition ,time ,temp, alt, humidity,car peramiters,so as to have all the info  one needs to dial in properly.
Dial-in or Index is all about consistency and equipment need not be the latest go-fast thing-a-gobob.

[George]

Sounds like a plan! Thanks.

[buickfed]

377 , 3.90gear 33" x 12" 18%over, 10" converter leave off idle on the hand brake

1.11 60' 4.55 1/8 @153.77mph

not to take away from George's question, how many or why leave off the brake vs stall rpm? is there a difference?

[dreracecar]

no battery needed (weight & malfunction eliminated)
Driver rolls in grabs a handful and stomps the peddle on yellow
no need to bring RPM up or down -full concentration on tree
ready if starter quick trees
By leaving on brake ALL qears,splines and couplers are loaded and dont take and impact (longer life)
Some cars rock back and forth (see above) when brake button is pushed because its locked inside the trans.
Driver has hard enough time walking and chewing gum at the same time--less to do and think about.
Driver can step into any fuel car and drive it because the controls are the same--grab brake and mash throttle

I must also add that after the driver returns from the burn out and is behind the line "I" adjust the idle launch RPM's to a pre-set posistion. That rpm does not change and adds to consistancey.

[George]

We started our deal with a battery on a cart. That proved to be too much of a hassle. We have a full size battery in the nose of the car, cables run inside of the top frame rails. The  weight was needed any way. I'm not a big fan of MSD but with the 2 step and rpm switch we have adjustable launch rpm , it shifts on an rpm switch and we have a top end rev control.

 I'm seeing some issues with the 2 step and blower ( cold cylinders on the 2-step) but I think the "convertor helper" solenoid by pass will clean that up.

I agree the 2 step is harder on parts.

[masracingtd1167]

George I think the 33 inch tire will tone it down a little . A gear change would help a lot but I understand that a4.88 is the only pro gear you can get for the Chrysler rear . If you are only running 1/8 mile you should be ok with the 4.88 . Are you using a 7al3 box ? When I was spraying mine with nitrous I could take timing out of mine with the box and a timer .

[dreracecar]

You take the street gears and anneal them a couple points--will work fine

[George]

MSD 12Lt mag