mac79vette

The last setup making 335 hp was on a dyno about 5 years ago. Now for the current set up during my restoration I disassembled the engine to inspected it and there was some scuffing in the cylinders so I had it honed and the crank turned and also had the stock rotating assembly balanced. I then changed my heads to the AFR 180 heads also. Also changed my exhaust from the 2 1/4 to a 2 1/2 mandrel bent system. I started it and did the brake in but have only driven it in the driveway. Currently the car is at a paint shop. I hope to have a bit more power but its going to be hard to compare when I have it on a dyno because last time with the old set up was at sea level and now I live at 5000 feet.

When do you plan on getting this engine together?

FireballXL5

Just found a semi local corvette shop with a dyno, and I'd like to test my 'true' numbers sometime soon... But, said shop is currently rebuilding my trailing arms and bearings... So my vette is down for a little bit while they do the work and order me a new rear mono leaf. Once I get it all back together I'll try to get a dyno for comparison... Here's the 'listed' stats on the 383 stroker that was transplanted in my 81...

Intake , holly double pumper , headers, 2.5" stainless exhaust, 700r4 trans... It's got all the right goodies.. Curious what it'll dyno out at...

jb78L-82

Thanks

My engine should be back together and in the car by Memorial Day-Hopefully...........

zuendler

If you want the same acceleration like a C6 GS you need to think bigger,
because a C3 weights a lot more. (~400kg more)
I have the zz502 in my C3, which is rated at 502HP (gross?) and the C3
has the same acceleration like a stock C6.

Unless your SB is not stroked and has a really wild cam in it, I would no expect
it running as fast a C6, not even talking about a Z06.

MotorHead

It can be done, this was my first baseling pull without any dyno tuning,
had a bunch of power eaters like baffles in the header collector and small headers, I would be looking for more RWHP the next time

[IMG][/IMG]

Shark Racer

JB's C3 is not going to weigh 4200 lb. In fact, since he's going with aluminum heads, it will be within 200 lbs of a C6, probably less than that. They have aluminum blocks, thinner fiberglass, a lot more plastic and better designed components to shed weight, but safety regs also keep the weight up. Compare the thickness of a C6 A-pillar to a C3 A-pillar. I'd rather roll a C6.

Nice, too bad I never put headers on my LS7 (that's actually my dyno sheet on the bottom).

Here's one with headers, for what it's worth:



When you toss in a cam on top of the headers vs the very mild cam they come with(211/230-119), they go insane:

jb78L-82

You are exactly right. In order to meet the acceleration of a Base C6/Z06 with a C3 with the weight penalty of the C3, much less efficient drivetrain and subsequent drivetrain parasitic HP deficit, and using Gen 1 engines to achieve the HP, you are going to need BIG Gross HP numbers from crate engines, especially SBC, less so with a BB. Your ZZ502 has somewhere around 365-375 RWHP which should certainly get you in the acceleration game with a C6 base.Matching the HP of a C6 is certainly doable with a BIG BLOCK, but to your point, achieving the same power levels necessary with a Gen 1 SBC is going to require serious stroking and cam, to achieve the RWHP needed to match a C6.

Motorhead's real world examples demonstrate that using a BB, the power levels are doable, but Zuender's point even with the equivalent RWHP from a 427 BB, the Z06 LS7 is going to win that one everyday with the big weight advantage versus the C3 and much more efficient suspension to the put the power down.

bebezote

very well put...

i finally gave up on the gen 1 game.... leaky oil, inflated numbers..etc... even a procharged 502 w alum heads... all just leaky, over heating, etc...

putting in a new ls7 w t56... finally saw the light..

cagotzmann

I have weighed both my 78 and 2010 GS.

78 full tank of gas at 3696 LBS
2010 GS full tank of gas at 3505 LBS

This includes me sitting in the car.
This was using a truck stop weight scale.

For me I think if I can get 335-350 RWHP I would be happy since the 78 has no traction control / ABS etc. Need to find that 6 speed tranny etc, Richmond 6 ROD. Not looking for off the line acceleration as much looking for a good road track / Street performer. You guys have given me lots of good info. Keep those actual RWHP numbers coming and how you got there.

jb78L-82

Whats the guess on the 10 GS's weight with very little fuel (Figure 6 lbs/gallon of gas) and no driver? Dry weight of my 10 Z06 according to GM is 3,080 lbs. 78's weigh somewhere between 3,400-3,500+ depending on options. My 78 definitely does not weigh 3,500 lbs dry with zero emissions hardware of any sort, lighter battery, no AC, no steel rear spring, lighter SLP 17 inch wheels, very few options-no power windows, door locks, tilt wheel, rear defroster etc, no cast iron exhaust manifold-shorties-MUCH lighter. I would like to replace the OEM seats with lighter ones but don't like the non stock look.

After reading much as well, I think that if my combo for the "new L-82" with the AFR 180 65 CC heads, Howards HRC (.525/.525, LSA 110, 219/225 duration), compression 10-10.2:1 does not yield 350-360 RWHP, I will be disappointed. 335 RWHP would be 100HP more than my OEM L-82 did on the dyno with pretty much just headers/exhaust.

Shark Racer

The last time I weighed my 78 it was 3450 with aluminum heads, fiberglass rear spring, headers, dual exhaust w/ cats, no spare tire (carrier still present), 700R4 w/ BTO tubular x-member. Other than the aforementioned exceptions, it was "stock", weight wise. Full tank of gas too. No driver.

I've gone to an aluminum rad and e-fans now, and a manual rather than auto. Well, RIGHT RIGHT NOW, there is no engine and trans so it's quite a bit lighter.

bluedawg

What transmission, if you figure 22% loss( this is what motorhead lost through a manual and you make 400 at the crank, you can do the math. What did you come up with for dcr? And what compression, did you come up with, 10 to 1 or 10.2 to 1? The only reason I ask is your cam shaft looks a little small fir 10.2 or 10.0 to 1, its real simple to figure the dynamic compression ratio and won't take very long. Regardless of what horse it makes, it will make you happy. But to expect 365 may be optimistic and an unreal expectation, you'd be looking at 480 or so horse at the crank at a 22% loss.

pauldana

Going to get to Dyno my 79 next week.... FINALLY!!!! hopping for around 550+hp at the rear wheels... we shall see:-)

bluedawg

Your through a manual gear box correct? With out rereading the 1175 posts in your thread Paul, What were you shooting for at the crank? Was your 550 rwhp with the n2o? If you were hitting 650 at the crank, you'd be around 507 @ the rear tire through a manual gearbox and 22% loss. I've not done the engine dyno, let alone one then the other, but I've done the chasis dyno once, What a hoot that was. Motorhead did the chasis dyno and then the engine dyno and came up with 22% difference through I believe a manual gear box, but you'd think that not all gear boxes are equal as a t56 probably robs less hp than a muncie and so on.

pauldana

shooting for 650+ at the crank... so over 550 at the wheels.... its is going through a lightweight twin disc clutch and lightweight flywheel to a TKO 600

Dyno next week!!!:-)

jb78L-82

[QUOTE=bluedawg;1586747221]What transmission, if you figure 22% loss( this is what motorhead lost through a manual and you make 400 at the crank, you can do the math. What did you come up with for dcr? And what compression, did you come up with, 10 to 1 or 10.2 to 1? The only reason I ask is your cam shaft looks a little small fir 10.2 or 10.0 to 1, its real simple to figure the dynamic compression ratio and won't take very long. Regardless of what horse it makes, it will make you happy. But to expect 365 may be optimistic and an unreal expectation, you'd be looking at 480 or so horse at the crank at a 22% loss.[/QUOTE

I have not calculated Dcr. The static compression is based on 9:1 pistons, add 1 point for 65 cc heads, .1/.2 for .015 gasket. May go with .039 head gasket. Builder says cam will be great with combo.

bluedawg

650 at the crank using the 22% loss would be 500 at the rear wheels, I'd be real happy with 500 rwhp, your running a light weight clutch you might do better than 22%.

[QUOTE=jb78L-82;1586748362]With out knowing how far in the hole the pistons set, the compression ratio is just a guess, If its the stock l82 pistons set up the way the general set them, then your quench will be to big and the 10.2 compression would be off, I'm not questioning your builder and with out further details I can only guess, some don't believe in the dcr, some do, but it doesn't hurt to know were you set with it, being 219 @ .050'' lift, I'd guess that the camshaft might be a tad small for the compression, but if it's still set up with the .0250'' deck hight that cam for gm then your compression would still end up in the 9 to 1 range and the camshaft would probably be in line. It seems to be the general consensus that general motors compression ratio's were off as the pistons were always set pretty deep in the hole. figuring the dcr, you'd need to know these things and you could adjust deck hight by the compressed thickness of the head gasket. I'm just trying to help, but shooting for 335 rwhp let alone 365 rwhp out of a 350" or a 355" takes some planning and being sure exactly what your compression ratio comes out to be is part of that planning. If you'd like to share details about the build. I think that your on the right track with the parts selection that you've bought.

jb78L-82

[QUOTE=bluedawg;1586748676]650 at the crank using the 22% loss would be 500 at the rear wheels, I'd be real happy with 500 rwhp, your running a light weight clutch you might do better than 22%.

Thanks for comments. Seeing the buikder

jb78L-82

[QUOTE=bluedawg;1586748676]650 at the crank using the 22% loss would be 500 at the rear wheels, I'd be real happy with 500 rwhp, your running a light weight clutch you might do better than 22%.

Thanks for your comments. Seeing the builder tomorrow and will share your thoughts. Stay tuned.

jb78L-82

[QUOTE=bluedawg;1586748676]650 at the crank using the 22% loss would be 500 at the rear wheels, I'd be real happy with 500 rwhp, your running a light weight clutch you might do better than 22%.

Not having the block decked-btw.