How much power will a stock 47rh hold... (not what you are thinking)

dvst8r

dvst8r

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In a 3000lbs rat rod.

I know in a stock 6000lbs 2nd gen they are only good for stock power or slightly more. I am guessing with half the weight, and obviously never towing, it should be able to handle 350hpish?

The owner just got it running after 2 years of building, and is hoping to make it through the summer on the stock trans, and then will have the trans built over the winter. I am thinking 350hp in that should keep him smiling for the summer at least.

Thoughts?
 
I can drive around in a 700 horse 12 valve with stock RH, it just depends on how you drive
 
Who wants to drive around babying a vehicle to make a trans live? I wouldn't...

Set it up to a power level that it will survive at and once he gets it built, start adding power.
 
If it's an RH, drop the pan, crank the pressure screw up to max pressure setting and refill with a mixture of hydraulic oil and type F.

That should make it through the summer with 400 HP in that light weight vehicle.
 
The owner built it with twins (hx40 over an HT3B) it is a 160 pump, with the stock 160 injectors. He pulled the plate before it ever left the garage for the first time, and has played with the afc some (haven't pulled it to see if he modded it or just moved it). Today I helped him put 4k's in it and bump the timing up to ~20. It moves out pretty well now, makes about 50psi of boost in od, and locked up. My guess is it is in about the 240whp area now.

He has a set of sdx 7X0.010's that he would like to put in. I am a little afraid those might be the death of the trans. I guess we will give it a go and if the transmission complains at all I will put a plate back in it.
 
Big Blue24 said:
If it's an RH, drop the pan, crank the pressure screw up to max pressure setting and refill with a mixture of hydraulic oil and type F.

That should make it through the summer with 400 HP in that light weight vehicle.
Click to expand...

Thanks.

It is a 2wd 47RH. Anyone have a picture of the pressure screw. (I am new to the auto world, all my own stuff is stick)
 
duck_04 said:
Who wants to drive around babying a vehicle to make a trans live? I wouldn't...

Set it up to a power level that it will survive at and once he gets it built, start adding power.
Click to expand...

I didn't mean it like that I guess.... What I'm saying is that with a stock transmission its anyone's guess when, and at what power level it will go. The way you drive it will determine quite a few factors (boosted launches, heavy, but normal acceleration, etc.... ) I would say build it to the power level you would like, kill the tranny whenever it wants to go, then build it to hold what you have or more... A lot more fun that way... Cuz let's be honest, I only like replacing parts that I destroyed, not ones that are in good working order!
 
How does that hx40 come to life with that light weight? I'm running a stock rh with a shift kit. Haven't put alot of miles on it yet but it's working decent right now.
 
It is a little sluggish, but it keeps that low end torque down, I think that helps it with traction though.

It is the only vehicle I have ridden in that people are asking to see it smoke. I will get some pictures of it up tonight, but when you ride in it, it is like riding in a gold fish bowl, everyone is honking and waving and thumbs up. Crazy I tell you.

Converter unlocked it makes about 40psi of boost over all.

This is not a dd, it is a sunny day only car, it will probably only see ~2000miles this summer. The owner says he will take his chances with the 7x0.010's. I will do some more reading on bringing the line pressure up.
 
Oh and it never see's any boosted launches. That just leads to silly tire spin, even just hard throttle off the line with no boost will spin them easy. He also has no plans to visit the track this year.

He doesn't drive like an idiot in populated areas, as it is so unique that if you were caught even once being stupid, it would be blacklisted and you would be hounded by the cops forever.

So other then a couple of quiet back country hiways, and some main hiway rolls, or hiway on ramps it gets driven pretty soft.
 
Big Blue24 said:
If it's an RH, drop the pan, crank the pressure screw up to max pressure setting and refill with a mixture of hydraulic oil and type F.

That should make it through the summer with 400 HP in that light weight vehicle.
Click to expand...

What happens if you do that with an re? I've only put it in about 8 turns so far, its got lots of room to go.
 
If he drives it like you say he will, then it will have no problem hold 350+ horsepower
 
Like Blue said hytrans tractor fluid, I really don't think you will hurt the trans with what your doing. If it won't hook it's not loading the trans hard. Sure would like to see some pictures of it?
 
It loads up on the hiway converter locked and in OD, but around town you never really see more then 20psi. With it being that light even off boost is enough to get you moving quicker then posted speed limits with ease.

I will take some pics tonight.
 
Pressure screw in this picture is the one with the orange spring, the more you preload the spring by turning the 3/16" allen head counter clockwise, the more pressure. Stock is about 2 turns and 90 psi. Every turn is about 3 psi and the adjuster bottoms out at about 11 turns so you'll only get 120-130 psi line pressure, but that's a nice 30% increase in torque capacity.


ValvebodyPressure2.jpg


ValvebodyPressure1.jpg
 
If second gear starts to shift funny, it probably bent the 2nd gear band strut from the increased line pressure. It's $21 for an upgraded strut, but you have to remove the valve body to install it because access is blocked by the valvebody itself.

If you remove the valvebody, you might as well install a $100 shift kit and get the line pressure up closer to 150 psi.

Picture of the strut, this is an upgraded one that is thicker with tapered ends. It runs between the lever and the band itself, hence it's called a band strut.
BilletLever.jpg
 
I need to adjust my stop in a turn or two to get rid of second gear starts practically. It holds first for about 5mph but obviously that's not ideal.
 
Thanks for the pics! It will be done before the weekend. We got the 60lbs valve springs and 7X0.010's in tonight and made one quick run after 11pm local time. The headlights aren't very good, and it is now way to quick to mess around when you overdrive the lights almost instantly. A quick stab of the throttle saw 60psi boost and 90mph on the gps.

We are going to get up really early on Saturday and try and get on the local airfield and do some better testing.

Right now my seat of the pants meter it falls between Tate (user name on compd) 's dually with a 13mm pump and twins (about 900hp at best guess), and 1100hp (user name on compd)'s 9.69 superstreet truck. This is scary fast for not being able to see, and being 4" off the ground, but not quite violent like 1100hp's truck (yet).

As promised here are a couple quick pics I took with my phone in the garage after the quick test run.

IMAG0046.jpg


IMAG0045.jpg


IMAG0042.jpg


IMAG0035.jpg


Other then the shell of the body, this was 100% built by hand in that garage, over a couple years. It runs a Jag IRS rear end.
 
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