Its my understanding to get 300 at the wheels of a auto you would need at around 400ish at crank.

 

Yes, approx. 25% driveline loss with the auto vs 15% loss with a standard.

 

closer to 25% with a turbo 400...18-20% ish with a th350 from everything I have read over the years...

 

Yup. As I said, approx.

 

I'd say you got there. With your peak power at 5400 are you looking for more bottom end power?

 

I agree completly, if you think the current intake is holding you back (it probably is) try an open 1" spacer which will add more plenum volume. I never think about the cut out devider, but on my 400" I figure the rpm range was 1800 to 5700 rpm and switched to the team g which has the air gap beat in every way except a little low end. If your still running the Quadrajet you'll either need to run am intake with the Quadrajet pattern or add an adaptor.

 

sorry though I started a new post

 

Let's see if I can give you some real world experience with the L-82 on a dyno:

Example #1: My 78 L-82 4 speed with 100% stock internal components with 65,000 miles on the motor, Shorty headers with 2 inch collector to 2.5 inch duals, Holley 4175 Q jet replacement 650 CFM vacuum secondary carb, comp cam roller TIPPED 1.52 rockers, everything else 100% stock L-82 including the aluminum L-82 intake, cold air stock intake, etc. 233 RWHP with a weak compression #6 cylinder. Pretty Darn impressive...easy 240-245 RWHP if all cylinders had good compression. Note Stock L-82 aluminum intake

Example #2: More telling. Forum member Karols 78 L-82 4 speed...we are friends and he lives nearby me. 100,000 miles on the motor BUT a few changes from stock L-82. Stock pistons, 882 OEM heads BUT an aftermarket cam of unknown origin, Edelbrock performer RPM, drop base air cleaner, no headers (cast iron OEM manifolds) with magna flow 2.5 inch duals, under drive pulleys. 248 RWHP

The difference between the 2 L-82's-one stock components except exhaust with shorty, not LTH, and the other L-82 with a cam, stock heads, Edelbrock Performer RPM w/qjet carb, and exhaust is a whopping 15 RWHP. My L-82 was NOT totally healthy at the time of the dyno run, no less.

The biggest gain on stock type motors is the exhaust...add a few horses for headers-Shorty or LTH. The heads and cam along with exhaust can give a BIG gain in HP. The intake on a stock type motor?..not so much... reference examples above.

I also spoke with my engine builder who did the bottom end of my 355 L-82 during the recent rebuild of the motor that LTH with my new combo would add lots of HP to the engine. I asked and spoke with him at length about the L-82 intake and he was very clear (and knows MUCH about all types of hotrod motors both old and New...builds stock Gen 1V8's to 1,100 HP LS motors ) that changing the stock L-82 intake is not worth the trouble unless you intend to rev the motor consistently above 5,500 RPM to 6,500 RPM and higher..period. I am no expert but my builder certainly is....hard to argue with the above examples and someone who I assure you knows more than most of us...The builder verifies most mods that he does on his in-house Mustang dyno.....pretty tough to argue with facts when he shows me the dyno before and after sheets...

Interesting aside the builder showed me the before and after dyno runs on his Mustang dyno for a bone stock C6ZR1 (638 net hp) of 550 rwhp stock and 625 RWHP with LTH's (american racing), Billy boat exhaust with no cats, and a K&N cold air intake plus an ECM tune....625 RWHP...75 RWHP gain...holy crap...700+ net hp !!! on a stock C6ZR1

 

Motor head pulled his 406" to run on an engine dyno after a dispute on the forum here when he'd already ran it on a chasis dyno and came up 23% difference through a manual gear box, automatics eat more power with the powerglide using the least and the t400 and the 700r4 competing for last around 30%,( havnt hears anything on the new six speed autos)all of this has variables, converter size, materials that the internal components are made of, half shaft weight and rim and tire weight, the heavier the rotating mass the more power it eats to spin it.

 

For comparison, my 1970 L-46 (an L-82 with more compression) is slightly modified, .030 over, ported original heads, Comp Cam xe262h-10, 10.4:1 c/r, original cast iron intake and exhaust manifolds, M21, 3.70, 2 1/2" under car exhaust. Engine had around 200 miles on it when I made the dynojet runs, 245hp/305tq (rwhp).
With five or six thousand miles now on the engine, I need to run it again.

Dyno runs on the engine dyno, open headers, velocity stack, no accessories, etc., 341hp/387tq (gross hp).

Good article on the L-82, http://www.superchevy.com/how-to/eng...-dyno-testing/

 

That comes out to 29%.

 

That is pretty much right on the money for Gross HP to RWHP on a dyno jet...30%. Much greater loss for gross HP to RWHP on a Mustang dyno....Mustang dyno s are more accurate for actual real wheel hp since the mustang dyno does not use algorithm tables to calculate RWHP like a dyno jet but actual resistance to the revolving drums...Most hotrodders don't like the lower numbers from the mustang dyno since the numbers are lower but more real world

 

1971 - 350: I used a Weiand Street Warrior with a roller cam, ported and flowed factory heads and got 400hp at the crank. The Weiand is a "low rise" and fits under my stock hood. Hot Rod magazine had a list a few years ago of manifold heights, This Weiand is pretty low, but pulls and flows great. Their test proved it .

The engine builder who did the dyno tune never used one, and now he stocks them. He said it was a great balanced flow and was impressed.

I went by height and the Hotrod's test numbers. I'm pleased.

 

I did the chasis dyno once and it was a hoot, we picked up 16 or so horse just by jetting the carb to the the best power that was either 12.6 or 12.8, don't remeber now. The guy that had the dyno was a good guy and for $250 you could make pulls until no more power was to be found, you were at the pedal and there to change jets, adjust timing ect and Richard the owner of Hails Technical would advise to changing jets or trying more or less timing, it was a real learning experience that was hands on. Great time. Richard sold the dyno and the folks that have it now are nto as hands on for the customer and don't want you at the pedal. I've found that the mph on the quarter mile works real well for telling the rwhp and you don't have to launch hard to get close to your top mph, it only cost's $25 here in Alaska and you can make passes for hours during a test and tune, you meet real good folks and have a ball doing it. I usually take the wife and kids and we have a good time for the family, I let my daughter make passes in my 2012 sierra. Probably never do the chasis dyno again.

 

BLUE1972...I would like some more info on your engine build. I'm trying to get to 400HP on my 1970 350 L46. I'm planning on using factory crank, rods and new 11.0 CR pistons. Factory heads if possible. What cam, carb and model Weiand intake???

 

With factory heads you'll be fighting g several up hill battles, a decent set of heads and you should be able to achieve 400 horse pretty easily.and with good manners.

 

 

I was assuming the same thing but I saw that Blue1972 had acheived 400HP with the factory heads. Was just curious how he got there. I would like to keep everything stock looking and still get a bit MO power. I'm assuming headers are a must....looking in to 2 1/2 manifolds as well. Sorry, didn't want to threadjack the other post. Will probably start another thread soon.

 

I used the following parts:

Heads: 2.02 / 1.6 valves w/ undercut and flow polish, bowl porting and flow porting for the heads (numbers matching = NM). , valve springs 331@520lift. The heads were hard enough not to need seat inserts.

NM - block- boiled, bored and honed, forged steel nitrided crank, Lunati cam 20120720lk, roller lifters, Weiand 8120 street warier flower/ ported and matched, forged and balanced piston set, Manley chrome moly push rods, Stock Chevy high volume pump / stock PSI spring, Eagle rods / balanced and shaped. Rotating assembly balanced.

A few other items... best run was at 38 degrees advance. which was repeatable 3 times. 12.8 AFR, 160 high flow/ balanced thermostat.

He loved the manifold as the AFR was 12.6 to 12.8 from 3500 to 6200 which he said indicated a good balance and flow. He gave me a 6500 red line, but I'm setting the rev limiter at 5600 as I want to keep the motor forever...

Tested with both the 650 and 800 cfm Edelbrock thunder carb- almost no difference. Holley carb not as good AFR during pull. Same HP numbers. Using the 650 on the street.

If you don't care about the NM - AL heads will be cheaper and work well.

 

Thanks Blue....exactly what I was looking for.