Mods to get to 7k rpm?

aharte · 11-12-2002, 09:31 AM

Is it possible to get 6500-7000 rpm's out of an old L82 if the top end is made to handle it, or does it need to be ripped apart and rebuilt first? I'm thinking of getting AFR heads and some other stuff, which would gain a lot more if I could rev the engine higher.

Crazyhorse · 11-12-2002, 04:32 PM

I'd say you'd want a complete rebuild, but...
6.5 - 7K RPM's is not really what you should be aiming for on your car.
Just select the proper components that will work well together to
increase HP & torque. Don't get hung up on what the red line will be.
A good investment would be desktop dyno to model your components with.

[Modified by Crazyhorse, 3:33 PM 11/12/2002]

gkull · 11-12-2002, 06:43 PM

My 79 l-82 short block stock made numerous runs to 7000+ rpm with various head and cam combos. So the stock forged crank and rods can handle it if the motor has been well maintained. I still have that crank and rods and plan on using them in some future project 355 ci. Although this rebuild they would get ARP rod bolts and of course a really nice balance job.

7000 rpm requires attention to spring closed pressure and valve train weight.

aharte · 11-13-2002, 12:08 AM

Quote:

I'd say you'd want a complete rebuild, but...
6.5 - 7K RPM's is not really what you should be aiming for on your car.
Just select the proper components that will work well together to
increase HP & torque. Don't get hung up on what the red line will be.
A good investment would be desktop dyno to model your components with.

I actually have desktop dyno already, and that's what prompted the question. Putting on a good set of heads with the current cam (I think its stock, but I'm not sure right now) and right intake/exhaust creates peak power around 6500 according to the program (and a lot of it).

It would also help some of my gearing issues. I'm ditching the 700r4 for an M20 or M21. I have a 3.08 rear, which gives a max speed of 140 mph at 5500 rpm. That's fine, except that I'd like deeper gears while keeping that top end. I don't like the ratios on the overdrive transmissions enough to justify the price.

aharte · 11-13-2002, 12:14 AM

Thanks gkull. How much power did that setup put out?

Twin_Turbo · 11-13-2002, 08:16 AM

The big end on the rod will be critical & the rod journal size too. You will have to get the rods resized because they tend to get egg shaped, mike the journals, then you can get the bearing clearances right. A lot of them have 0.0005" oversize bearings from the factory to take up for machining tolerances.

Marck

gkull · 11-13-2002, 02:46 PM

The fastest 355 ci combo I ever had was 12.38 @114 with slicks. I have a 4.11 rear and 700R4. Instead of a manual tranny it would be cheaper for you to install what i consider to to be the best gearing for a 700R4 and that's a 3.90 rearend. It gets your overal gearing in OD to about the 2.73 range. With 28 inch tall tires you would have to have a powerful 355 to ever hit 6500 rpm in OD and a big set of nut's ;) I have driven my car for extended periods at 6500 rpm

aharte · 11-13-2002, 03:53 PM

I'm not really putting in the manual transmission for any performance benefit, although I do think they're superior for road racing, which is mainly the type of driving I do. Manuals are just a lot more fun in my opinion.

gkull · 11-13-2002, 05:45 PM

I help a friend convert his 78 to a stick. I was a PITA. It took a little bit to aquire the petals etc, but installing them was a job designed for a midjet contortionist.

I had a 700 with a full manual valve body. It's like a clutchless 4 speed. I drive a 5 speed nearly every day if I don't take my Vette. Manuals are fun :seeya