jjohnston

I have the LT1 bolted to the 700r4 trans. How much power can this trans actually handel? I want to do a bunch of upgrades to the LT1 (cam, heads, intake, etc.) but don't want to blow the transmission. because If I do all this other work, I won't have enough to fix the trans if it gets destroyed.

jjohnston

Maybe I can answer the question a little better. Can it handel 420 horse power??

Dyno Don

iTrader: (7)

Lot's....but not for long. They are known for being a weak link.

jjohnston

I have a company that says they can upgrade my 700r4 to handel it. should I trust that, or just look at a new one. and If I do a new one... what should I look at? I hate to do a new one, because I just did a lockup kit, vss etc to make the 700r4 talk to the new LT1

eric1984z28

It can be upgraded to handle the power. In stock form it won't last long at all though.

arnold

I have a 91 Camaro RS and want to do a engine swap from a 305 to a 350. Will the stock transmission work or will I have to upgrade it or get new or different one?

jjohnston

I just finished my LT1 swap. I also had the 91 RS, Mine had the 305 too. I used the stock trans (700r4) and it seems to be working just fine.

I've heard... the 700r4 can handel up to 400 horse. anyone please correct me if I'm wrong on that.

arnold

How many miles have you driven since the swap? What was the 0-60 time before and after the engine swap?

I've heard that the engine can be damaged if the new trans can't handle the extra power and it slips.

jjohnston

I never heard that. I hope thats not true.

I have put about 1500 miles on it since the swap. I've been driving it pretty hard. but I had to put it away in storage. Dang winters. don't know the 0-60 time, but its MUCH faster than the stock 305. and I'm running stock exhaust from teh 305 and everything. so I konw I can open up a little more by swaping out the exhaust.

heavy_chevy29

im most likely going to put a 700r4 in my car very soon. i was going to go with a th350 but i would really like to have the overdrive.

arnold

Are you using the same throttle body fuel injection that comes with the RS 305?

lowflyr

No, a slipping trans will not damage your engine. Well, I suppose if you were to keep the pedal mashed when the trans slipped so bad that it let your engine soar to stratospheric rpms and you still kept your foot in it, then yes it could damage you engine.......er, no wait, your lack of foot control would damage the engine, not the trans slipping. So I guess its still a no.

Anyway, fairly simple upgrades can make the 700r4 handle 400hp....just don't be revving up the engine and dropping it into gear.....this is just stupid and will break your trans, regardless of modifications. Call a reputable transmission shop and ask for a quote to make your trans strong enough, call several places because you will find large differences in the quoted prices. If someone quotes you $1500 to get your trans to handle it then they are either overbuilding it or ripping you off.

A good way to guage what is required is to read the websites of the many transmission rebuilders online and see what they sell in their transmissions that they rate for the power you desire. Read what modifications they make to these tranny's. I could list everything out that I feel is adequate, but in the end, you probably would rather get someone to build it that will offer you a warranty on their work.

Fastbird

iTrader: (5)

a 700r4 to handle 400 HP is not that far fetched. Anything above that gets very pricey. Another thing that has to be considered is to what RPM are you taking the motor (yes it makes a difference). Also if you are drag racing the car, will it be on slicks?

About $1000-$1500 for a trans to handle 400 is reasonable. One built to handle 500HP will be around $2500. If anyone tells you they can build a 700r4 to take more than 500HP, walk away.

I am on my 3rd high dollar 700r4. Next time it breaks (not if, when) I'll be swapping in a TH350. I have a nifty collection of pieces that I have found in the pan over the years.

vingta1989

i have had my 700r4 for a few years i have a local guy who builds all my tran missions he can build a 700 llike no one else i have had many others...i have run in the mid to low 10 sec range on this trans for 2 seasons plus driving the car all around..it wasnt cheap to build but it didnt cost me 3500 .00 either..regular maintenence and its fine plus i used nos too so i think its a pretty good transmission..th350 are great as are 400 but driveability??

bilms01

talk to Art Carr and tell them what you are wanting to do. Of course they will probably try to sell you something. They are one of the best at trans work. I use some of their parts in a 200r4 behind a Olds W31 325hp/350 and never broke it.
http://www.artcarr.com/

arnold

I'm swapping a 305 with 260,000 miles on the stock 700r4 for a rebuilt 350. I had the trans serviced every 40,000 miles and it works fine. It would only be a 75hp increase, I don't know about the torque. Do I need to upgrade the 700r4 to handle the extra hp and torque?

85Firebird350

iTrader: (3)

I guess some upgrading is in hand for me. I'm probably at about high 300's now for Horsepower and I want to throw in a big cam and AFR heads. Should I just swap from my 700r4?

vipershark11

iTrader: (6)

could the tranny handle a weekend couple of races with nitrous bringing power levels to about 350? but other than that running low power levels every other time?

TheDon

The 700r4 can handle roughly 600 hp if built properly, with a few shift packs of course.

Pro Built Automatics

I have 700R4's available starting in the 450HP & up range, all the way to 700HP+, it depends on what you are doing as to what will work best for you. If you want build the unit yourself, I carry the rebuild kits, videos, and build books, to build anything from Heavy Duty to all out racing. These kits are very complete and have everything that is needed to do this correctly.

heavy_chevy29

Pro Built Automatics

do you have a website i could check out

Tobias05

www.700r4l60e.com

Shagwell

Pro Built or PATC (raptor) can build you a 700r to handle 700+hp. Mildly improved stockers (servo/vb kits) are good for around 400, with decent clutches 450-500.

But, although many shops claim it, those are the only two I trust to actually make one take anything over 425hp.