I'm putting together what I hope will someday be a 12.0 sec car. And from what I've gathered that should require about 420hp.
I won't post my combo and ask for your opinions on that, I'll just say that the basic concept will be a 400+ci engine putting out slightly over 1hp/ci ... I'm not exactly sure of the specifics at this time.
My reason for wanting to do it that way is because in Calif, having a rough idle will get you pulled over. And with a big inch motor, I can have my 400+ hp and still idle fairly smooth.
So... I'm thinking that what I'm aiming for would probably be a torque peak at roughly 4500-4800rpm and peak hp at about 5500-5700.
So... enough background information.
Here's my question.
With a 12 sec car that makes tq & hp peaks at the rpms above, what rpm should I expect to cross the finish line at?
Also, I'd like to stick with my 700r4 (modded of course) and with one of these trannys, are guys finishing in 4th (od) or in 3rd gear? With the converter clutch on or off?

Thanks, of course, for any help.
Hope you're all having a great weekend.

 

try this calculator

I would say that depending on tires your probably looking at a 3.42 rear end. Should cross the line in 3rd at your peak hp.

 

The 7004r and TH350 trap the same rps at the big end, I've personally been there and done this, not an A-B-A test, just a A-B test. Alot is going to depend on your cam/convertor on where your rpms are going to be at. With my 355 I was running 28" tires, 3.73 gears and a fairly tight 3500 stall and I trapped abour 5500 rpm. Not a freind of mine with a convertor that's a little looser goes throguh the traps at 6800 and he is only running 4.11's in the rear with the same height tire.

The cams power range and actual output will be the ultimate factor of where you need to be with convertor which is a huge factor in where the motor will rpm. I know a guy with a loose 8" that shifts his BBC at 6400 and his shift light is on before the 1/8 mile all the way through the 1/4 traps since he has soo much convertor slipage, the tach only drops about 200 rpm between shifts.

With a off the hip guestimate I would say a 28" tire, 3.73-4.11 gear, and a decent 2800-3000 stall. and if properly set-up you wont be close to hitting OD anywhere in the 1/4mi. and if you do be prepared to smack your face on the steering wheel with the huge lose in gear reduction if you do.

 

Thanks for the input, guys.
It's good news, cause it sounds like my 3.42 gears should be good for a starting point. And then by the time that rear end is gone, I'll have a better idea of what to replace it with. Also I'll be able to substitute a th400 while I'm getting the 700r4 built up.
....Should be interesting.

 

what are you goals for this car? daily driver/weekend racer? Street racing? 1/4th mile(or 1/8th)? weekend toy to play with the riceboys? If this is a race only application I'd say stick with the 400 as it will hold up much better behind something making a good amount of power.... If you are going for street/highway racing i'd stick with the 700 as the OD will no doubt benefit you in top end MPH..

 

What my goals are depends upon how hooked on racing I become.
I'm trying to figure out a plan for if I do get really addicted.
In Cal. though, a person can get into a lot of trouble if they get caught "disabling the factory smog equipment" and it calls for some really imaginative thinking if you want to drive a fast car in this state.
Basically if I decide to take racing seriously then I'll have to trailer my car to the track.
If I want it to be a street car, it will have to be a sleeper. A stroker crank is easier to hide than a lopey cam.
Possibly I'll have a racer during the summer, with a head/ intake/ cam swap. Then during the winter, when I don't feel like riding my cycle, I'll put my car back to being street legal.

Heck! ....I dunno! What I really want to do is illegal.
I look at the pics of the engine bays that some of you guys have and it makes me wanna cry. I'd like to just build up a car and run it with the engine totally stripped of all the spagetti.

 

Easy solution for wanting to do what is illegal...get out of cali

 

If I wasn't hooked on surfing, that's what I'd do.
Life's full of compromises...

 

This might sound kinda vauge, but I think the best rpm to be crossing the finish line at would be around the rpm where hp peaks.

 

That doesn't sound too vague to me.
Mainly I wasn't sure whether guys racing with the 700r4 were crossing the finish line in 3rd or 4th, therefore possibly requiring a different axle ratio than with a 3 sp turbo h/m.
So that question's been answered anyhow.
As far as what the car's intended purpose is, It just can't be so radically built that I can't run it on the street. So my plan is to put together a larger displacement motor that's got a relatively mild cam, that I'm hoping to get over 400 ponies out of, and I'll gear it a little bit higher to give me something like 115mph @ 5300rpm.
And it's looking like it ought to work out that way, at least on paper...

Thanks again for the help