Simple question, I’m not expecting a simple answer, but I’m starting to suspect it’s possible.

How do you make a th700r4 live behind a 700hp or so, power adder small block? Seems like every tranny vendor out there has something that they claim will do it, but with most of them I’ve noticed that there is also a string of unhappy customers that have blown their top of the line stuff with ½-2/3 the hp/torque.

I’m starting to see a string of 4th gen and other vehicles (especially the GTO’s and the b-bodies, which are both much heavier), where the 4L60’s are surviving into the low 10’s and even high 9’s, and after all the 4L60’s are really just the evolution of the 700. Isn’t one of the vendors (BMR maybe?) running a GTO with a ton of spray that is in the 9’s and is still running the 4L60? So what are they doing to get there?

FWIW, my combination will probably make all of it’s power before 6K rpm, so expect a bit of torque.

 

The answer is a lot of little things that will add up to make for a tough trans. Dana at Pro-Built has a 700R4 in a customers car making that kind of power, and it has lived through hundreds of passes.

I would start with a call to Dana www.700R4L60E.com

I would say you are looking at one of his master rebuild kits, a Beast sunshell, and a bit more. The thing about makign the 700R4 live under this kind of power is that the devil is in the details, and specifically the blueprinting. The best parts in the world installed incorrectly won't cut it.

 

I’d love some real input from those that have actually done it.

This also raises another issue… is this going to end up a high $$$ combination that I’m going to get stuck refreshing regularly or could I expect it to be fairly reliable once it’s all ironed out. The thing is that this is a car that sees a bunch of street miles, and although that is a big part of why I’d like to stay with the 700 (OD is nice on the street), something that I can’t rely on is worse and I’d be pretty annoyed if I tried 2-3 itterations and then finally gave up and went with something like a TH400 (lets face it, a TH400 with minor upgrades can go seasons at this power level reliably).

 

Not sure what you are looking at $ wise, but i'd say consider the 4L80E, its been done in the 4th gen. Yes it will probably require a seperate controller, but I cant explain how nice a thirdgen with a 60E drives around town.

 

Honestly, at the power level you are talking about a 4L80E is a better choice. I don't know that you are going to find anyone on this site that's got a 700R4 at that power level, because most swap to something different.

I can tell you what it takes to get a 700R4 up to the task of 550-575 HP, because that's the way I built mine. You are talking about another 125-150 hp. I think that at 700 hp you would be refreshing the trans often, and I don't know how reliable it would be. Also, everything would be critical at that level. If something was even the slightest bit out of spec it could cause the trans to fail.

I'd say go with the 4L80E up front. It's expensive, you will need a seperate trans controller to make it work, but it will live. A 4L80E is basically a TH400 with OD and electronically controlled shifting.

 

Do a TH400 and spend the extra money on a Gear Vendors overdrive. Might be a decent route to take.

 

to your question!

well, the big improvement is 4l60e can control line pressure at the shift points and control the shift way better than the 700r4 not to metion it can be raised for holding power.

I can't see a way to get the 700r4 to even come close,

more clutches=wear sooner (not to mention the 4l60E can too)
high line psi +harsh shifts = break things (very quick in the 700r4)
Replace everything with heavy duty steel parts to handle a harsh shift very pricy not to mention the shock of the hard shift will still break things

sorry never ran even close to that much hp with a 700r4, ditched it long time ago