Will a Stock 489 handle 700hp?

Have you had a stock 8.75, 489 hold up to 700hp while racing?

  • Yes

    Votes: 11 27.5%
  • No

    Votes: 29 72.5%

  • Total voters
    40
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IMO, forget about the sturdiest rear end, drag strip performance or a chassis dyno. Get it on an engine dyno first and perform proper tests with as few variables as humanly possible. If this device is as revolutionary as you say, you should sell everything you own if needed to get its capabilities verified.
 
Close to it. I can't say 2x as an absolute, I'm saying it is close. If you were here Grumpy, I would let you put one on your car so it would open your eyes wide and you would go "wow".

I have tried to be as open with this as possible. I have facts and data I can't share with you guys. You keep probing me for information, I asked simply if a 8-3/4 would handle 700 hp... I got a million answers, a million questions, and your criticism. I asked a simple question. Let me determine if a 8-3/4 would work... Hmm, nope. I believe now I need a Dana. According to all the replies I've gotten, 700 is around the hp where a 8-3/4 would break under low rpm, take off, which is where I was wanting it to be strong. If I had said I was working on a gizmo that produced 2x the low end and wanted to know if a 8-3/4 would work, I would have caught all this flack at the beginning. How many people have a diff rated at 500 hp and have broken it with a 500 hp motor? Or a 700 hp diff with a 700 hp motor?? I am producing more torque than a 500 hp engine will produce normally, I calculated to think that maybe a 700 hp rated diff would handle it, and perhaps it won't. I don't take chances and don't want to spent $2000 on a diff that is going to break. That's all I was asking.

You have your answer. I will post the results. Please let this thread die.
Thanks,
Bob
Sounds like u were willing to take a big chance on an 8 3/4. U shouldn’t of even considered it. Kim
 
Oh man...I cant let this go....I have a small block that makes like 455 ft lbs in that rpm range. Are you saying your gizmo will get me 900 ft lbs?

"Maybe 800" IDK, I am trying my best to get it on a chassi dyno to find out.
 
A true 700 horse is 140 mph at 3200 pounds. And no, a 8.75 wont live at that power.
I broke mine the first weekend i started going 10.30’s with a new combination at 3350 pounds. 128 ish mph. That might be a true 600. That was foot braking
Unless the car is real light, doesnt make a ton of power, or both, you are on borrowed time

Thanks
 
Sounds like u were willing to take a big chance on an 8 3/4. U shouldn’t of even considered it. Kim

The "mechanic" as he calls himself, told me an 8-3/4 with a 742 could handle it if I'm not popping wheelies. From what you guys are saying I need a Dana. But I have a good strong race 489 in it now, the housing has a brace, my car weighs 2900 lbs empty, or so it says on the title, but that was with a /6. I have a 360 block in in now, and a 727 as opposed to the 904 it came with, so with me and mentioned mods maybe 3300. I do not plan on popping wheelies, just a smooth take off consistently should provide an et difference that would be impressive enough for an investor to find it interesting. I know a pro drag racer and may have to pay him to get the consistency on the peddle I need.

I don't plan on racing it in competition.
 
IMO, forget about the sturdiest rear end, drag strip performance or a chassis dyno. Get it on an engine dyno first and perform proper tests with as few variables as humanly possible. If this device is as revolutionary as you say, you should sell everything you own if needed to get its capabilities verified.

I'm trying.
 
If you are not launching it hard you might be fine with the 8 3/4....just know that sticky tires and a hard launch could break it.

Might as well mention this too, my 8 3/4 has held up fine over the years. It has survived years of nitrous launches (~9 years) and the more recent (the last 11 years) is has survived stroker motors beating on it almost every weekend in the 10's. This is on a 3250# footbrake car. I know that I'm on borrowed time, but just know they can survive.
 
If you are not launching it hard you might be fine with the 8 3/4....just know that sticky tires and a hard launch could break it.

Might as well mention this too, my 8 3/4 has held up fine over the years. It has survived years of nitrous launches (~9 years) and the more recent (the last 11 years) is has survived stroker motors beating on it almost every weekend in the 10's. This is on a 3250# footbrake car. I know that I'm on borrowed time, but just know they can survive.

Thanks, I plan on doing some chassis dyno testing with it. I think it will be fine. I do have drag radials on it, couldn't find 50 series in a street tire. I just have to be careful until I get a Dana under it.
 
My 8 3/4 stock rear was making some awful noises when I was running High 11s in the quarter, probably bearings going out. Rather than spend more money on the 8 3/4 I built a junkyard Dana 60 because I had plans to make more power.

My car has recently gone a best of 6.27 in the 1/8th mile with the Dana 60. This is with Dr. Diff's truetrack and stock truck 3.54 gears. I do however run 35 spline moser axles.

Mine is also a street/strip car. I would just spend the money on the Dana and forget it. You will get addicted to going to the track and if it's a street car you don't always want to trailer it because you are worried about blowing up your 8 3/4.
 
Thanks for the reply Walker,

Yeah, I agree, I would rather have overkill and not have to worry than under and have to baby it afraid to really get on it. Good point there...
 
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