So I was able to make a first Dyno pull today ....

Engine:

383 ci, 10.2:1 Compression, Trick Flow Heads, Edelbrock 800 CFM Carb, Edelbrock Performer EPS manifold, Lunati HR cam 227/230 @ .050 Lift 478/480 with 1.5 RR, Flow Tech Headers, Mandrel bent 2 1/2" exhaust, X-pipe, Magnaflow mufflers, TH400 TCI Street Fighter w/TCI 2400 Stall....

I need to go check the timing but I think it is set at 34º all in by 2500.

It made 271 HP / 304 TQ..... (Dyno sheet below.....) I only made one pull - since it threw the PS and AC belts off.....LOL

I was really wanting more but I think the carb and manifold is holding it back.....

Thoughts?

 

That combo will work fine. Smooth and reliable. Me thinks the cam is holding you back. That's a small block cam. Punching that 350 out to 383 you are getting into big block CIs. To make more power you'll need a little more duration and a lift in the mid 500s, maybe a little higher.

 

Specifically which Trick Flow heads?

 

Here's the Dyno sheet....




The Heads are Trick Flow Aluminum 23º , part number TFS-30400002, 64cc Comb Chamber, 195cc Intake port, 1.470" springs ().540" max lift).

 

Dont really think you have enough cam for the cubic inches and the the head capability. I ran a 355 / 461 heads stock, standard performer, headers, Lunati bracket two cam/525 matched, 9:1 277hp My two cents...

 

Somting wong, I made much more HP and TQ with a warmed over 355ci, but of course it had gargantuan 200cc heads on it

Look at the easy stuff first, always before a dyno pull make sure your getting full throttle when you put the pedal to the floor, do a check for the secondaries opening all the way

 

I agree. Check everything, timing,valve adjustment,WOT,vacume ports, E brake on??? LOL Kidding....Vic.

 

Hopefully the dyno operator checked for the basics, but I agree that you need to double-check. I've seen the butterflies not be vertical more than once on an engine that's down on power.

The carb sizing is definitely not holding you back. The dual-plane manifold isn't holding you back with the flow of those heads. I couldn't find a matching cam with those specs; but you are leaving something on the table there with flow on the heads increasing right up to .500. The quick fix would be some 1.6 rockers that would put you at .510/.512.

http://www.trickflow.com/partresourc...y=chartsguides

None of this accounts for the power numbers you're seeing, and the story is in the curve. If the carb is opening all the way, I tend to think that a) you have a significant timing curve or misfire issue or b) fuel starvation. Validate the timing curve to be SURE it's all in < 3000, and check your plugs and wires. Then put on a fuel pressure gauge near the carb to be sure you're not hurting there.

I wonder a bit at the TH400 and converter...

Bottom line is there's nothing in the components I can see to choke you back that much. You should be making around 1 HP/CID at the crank, and so around 325 or so at the rear wheels.

 

I have a 355 w/TFS, Air Gap, 650 Demon, 218-225 w/1.6RRs, stk Ex man.
I get 280rwhp and 315 rwtq and the ex is holding back mucho power.
There is something wrong w/engine. Don't be surprised when you find something obvious. JMHO

R

 

If that is RWHP data...with a THM-400 tranny...I'm not surprised by the numbers. Check to see that the carb is fully opening when you depress the accel pedal to the floor. Testing it by hand under the hood is NOT the same thing. Also, your cam may be too mild for good utilization of the other components. Lastly, the THM-400 will eat up somewhere between 50-70 hp since it has no lockup clutch; it is "bullet-proof", but very inefficient as a trasmission.

 

....... too small of a cam. 525-550 lift and 225-235 dur would be better, my personal opinion.

 

 

yep also the th400 is costing around 20-25 hp......

 

To read the dyno graph correctly that little rise at the end doesn't count. It's just when you chop the throttle and the load causes a spike.

So in actuality you are all done at @5200 rpm and you are past peak TQ and HP.

IMO the cause is the lack of performance "Performer" manifold. In their own words it is for truck and RV's The small volume runners are choking even smaller 350 ci motors to sub 5500 rpm

This small-block Chevy manifold has a runner design that's "tuned" for peak torque around 3500 rpm on a 350-inch engine and it's ideal for power from off-idle to 5500 rpm.

Then you threw on an 850 carb. Where a 600 or 650 should be sitting. That manifold probably doesn't flow much over 500 CFM in a standard bench test

Any motor is only as great as it's weakest link.

 

Ok, yes those are rear wheel numbers which is why I stated the TH400 - I know they eat horse power.....

Here's the link on the cam: http://www.lunatipower.com/Product.aspx?id=2009

I had the duration incorrect it's 227/234 @.050. So I think I'm just shy on the lift....right?

If you notice, the HP in the chart hasn't nosed over yet..

The complete ignition set up is suspect but definitly not all of it.

 

How do I verify the secondaries are opening on a Vac-secondary carb without having it on the dyno?

I will double check the primary tomorrow. Last time I checked it was good.

 

34 total seems a little conservative?????

 

It's done at 5000-5200RPM as gkull noted the little blip at the end doesn't count it is something that happens sometimes when you let off the gas on a chassis dyno. You are closer to 260 RWHP.

Like I said check all the easy stuff first. Get someone to press on the gas pedal while you look down the carb is the very first thing to check

 

You are getting over 200 hp at 3500 rpm. You should be seeing more than 270 [or so] at 5500. The HP 'curve' has a very shallow slope above 3500...where it should be fairly steep. Something is limiting the engine in what it should be able to do. I suspect carb performance is your biggest problem with the cam being a secondary issue.

 

Ok, the Performer EPS was used because of the hood height on the early C3's. I am running the LT-1 drop base and 3" filter.So I think there a little room to give but not much without placing the air fliter lid close to the top of the carb.


Gkull - any recommendations on intakes?

I double checked the carb and it is an 800 cfm but 50 cfm isn't going to make a big difference. Everything is plumbed (hard line) for this carb so I'd like to make an attempt with it for now.

I can increase the lift in to the .5xx" range with some 1.6 RR. I suspect this would just be icing on the cake at this moment.

I still think the ignition is suspect. I've had issues with it since I purchased the car. It was points and locked down with no mechanical adjustment. It currently is a PerTronix II. I've had a couple of phone calls with Lars on it.

Tim