All this talk and questions about horsepower upgrades and traction, I've starting wondering:
(A question to those of you who've been there)

With our stock suspension setup, how much horsepower can we put to the ground with "normal" street tires (no drag radials, etc). If we upgrade to more than "normal" tires -- when do you start breaking things?

IOW what is a relatively "safe" RWHP? With normal upgrades, IE u-joints, and maybe the dragvette extra link...

 

I had modified a couple of my 'vettes. First I took a '70 LS-5, M20 3:08 ratio coupe and replaced the 390hp 454 engine with a correct 1970 LS-6 engine, that came out of a Chevelle automatic car. I had it completely rebuilt to stock specs, back in 1987, for a sum of $4,117.00 then. The only item, deviated from factory specs was I had to go .0010 over on the bore, everything was GM parts, including the AIR system installed. Engine dynoed at an AMAZING 493 horsepower in stock form. Nothing else on car modified other than the use of 265x50x15 Euro T/A tires on stock rallye wheels. Nothing on car broke with this configuration.

Second car was a '71 LS-5, M20, 3:08 ratio coupe, took the original 365hp 454 engine and modified it by cloning it, to a L88 engine and specs, added headers and '69 style side mount exhaust. Otherwise drivetrain was stock as built. Engine dynoed 560 hp,had several problems with this situation. Disentegrated center of clutch plate, sheared off distributor drive gear, blew water pump off front of engine, 3 pieces held on by the hoses, stuck 1 fan blade partially thru hood, and hood popped up from force onto safety catch position.

So I am thinking that the threshold for parts needing to be of HD design probably rests somewhere around the 500 hp mark with stock bigblock components.

Just my .02 cents worth.
Big block shark lover forever!

 

I would agree on 500 HP. Anything more than this with street tires and you are going up in smoke. My 400+ SB has a huge problem hhoking on street tires. Slicks is what breaks driveline components. The instant HP being sent to the driveline will break parts. I have resisted putting on slicks because Iwant it to live. I figure I could probably take about 1/2 second off my 1/4 mile time but I might leave parts behind.

 

Sounds like everyone is talking 500+ flywheel, correct?

 

Yes. flywheel

 

If something like this setup was bought, the 1480 axel kit http://tomsdifferentials.com/cat22.htm how much hp could the differential take before the posi casing or gears start letting loose?

 

The center sections are really pretty tough. As long as they are in good shape, they will hang a long time. You could use a new style Eaton posi with the stronger spider gears and still keep the 10 bolt configuration and do pretty well.

The first stuff to go for me with slicks was actually an outer stub shaft. I know of a few other folks with same issue. After that it was a u-joint and then a halfshaft or two. But remember I was running 11.20's with a 427 on slicks. I was "walking" it of the hole at around 1500 rpm to save parts and then pounding it the rest of the way down the track.

I was using greasable ujoints at first. Once I went to solid Spicers, I had no more issues. I was also using stock C-3 style 3" halfshafts, figuring they were better than the C-2 and early C-3 2.5" ones.

One of the tricks to keeping parts alive is to keep U-joints out of a bind. That means eliminating much of the Squat action and wild camber change on launch. The Vette Brakes Smart Struts kit does a great job with this. Or you can modify your stock setup to do same thing almost.

You can get super strong stuff in the 1350 series joints that will live almost forever. it ain't cheap, but when you comapre what they get for a complete 9" assy these days, it's not too crazy. *IF* you go with the 12 bolt guts inside the Vette diff...you can run deep into the 9 sec and 8 sec range in the 1/4 mile and never have an issue.

The basic suspension on the rear actually works very well with just a few tweeks.

I'm using all 1480 series solid Spicer stuff now with the Dana 60 IRS..hopefully it will hold for awhile. Lots of overkill...but I'm paranoid!



JIM

 

Gordon.

It is a simple case of "Irrestible Force" (high-horsepower) in-front of an "Immovable Object" (traction/slicks), and like the title of the old Marilyn Monroe movie.....
"SOMETHING'S GOTTA GIVE!!!!!"

When I first began racing my '79 Z28, it ran mid-13s on sticky-street tires with the OEM 8.5" ring-gear 10-bolt rear-end with NO problems at all.
When I began using slicks, I up-graded to a re-built 12-bolt (spool, H/D axles, C-clip eliminators, etc.), built by a buddy who'd put the same rear-end into an 8-second BB Mopar chassis car.

The same guy who built that rear-end has been tinkering on hot-rod cars and Corvettes for almost 40 years, and when he swapped the 2.87s for 3.73s in my '82 Vette, he was told me, VERY seriously:
"Don't EVER go putting even your old sticky-street tires on this car with that Dana-44.....even-WITH that wimpy Cross-Fire in-front of it.... it wasn't made to handle much power at all....."

 

I don't know about rwhp but I have a 406/ 475 hp sbc in my 78" . The first part to break was the th350 trans. Replaced that with a B&Mth350 trans. Then the "u" joints went. I replaced those with brute force "u" joints. Then i pulled out one or my side yokes. (to soft a rear spring ) The spring let the half shafts get to flat. I called dan van Steel and he built me a hole new rear end. This is what i now have 4.11 rear end ,VBP 420# fiber glass spring , All poly bushing . Adjustable strut rods. 3" carbon fiber 1/2 shafts. I got all this from Dan Van Steel. Not counting labor (my own) I have over 4 grand in the modifications. I did this last year and sofar No more broken parts. I'am sure most people here with about the same HP. have went close to the same thing with their cars.All of us on the forum have learned the hard way at one time. I just wish I had used these guys advice first Now I want to go big block like Jug Head did , it never ends.

 

http://home.earthlink.net/~geaton/

1.36 60' with 28 X 9 MT slicks and stock third member.