Droshki

Engine:
383 Cu In (5.7 Rods)
Forged 4340 Crank and Rods
SRP 4032 Forged Pistons, -31cc Dish, Static CR 8.3:1

Cam:
Hydraulic Roller 08-301-8
Duration: 276/288 (I/E)
Duration at .050: 224/236
Valve lift: 502/520
(I) Open 30 BTDC Close 66 ABDC
(E) Open 82 BBDC Close 26 ATDC
LSA 113
1.6 Rockers

Heads: Holley SytemMax II
Valves: (I)2.02/(E)1.6
Chamber Size: 68 CC
(I) 243 CFM @.050 Valve lift
(E) 188 CFM @ .050 Valve lift

Induction: B&M 144 Supercharger (7 lbs boost)

Exhaust system: Hooker headers w/4" side pipes w/ baffles

Could someone run HP/TQ numbers for me please. I'll be putting this all togther soon.

Tips and advice welcome.

Pool is also open on how long my 350 transmission is going to last

Droshki

ttt

cv67

That car is going to flat out rip. Nice torque combo IMO.
Buy sticky tires.

Droshki

Im not going to buy sticky tires until I get a stronger transmission. I'm really afraid of what would happen.

Anyone that can plug these numbers into a program for me please?

c3corvette77

try downloading the camquest software from camp cams. it's free. you can plug in your combination and it'll show cams that work and give projected HP and torque numbers. the numbers might be a little optimistic but it's a ballpark.

Droshki

I did, when I was selecting the cam.

It said I was going to make 200 HP.

Nobody at Comp had an answer for that, even though it's their cam and their software.

Thank you for the tip though.

billla

I'll run it through my DD Advanced

- What carb?
- Do you have a link to the head flow numbers?
- Do you have a link to the cam card?

I'm far from a forced induction expert, but DD is asking for:

Island flow CFM
Impeller Speed RPM
Peak Efficiency %
Surge Flow CFM
Belt Ratio
Boost Limit PSI
Pressure Ratio
Internal Ratio
Intercooler %

Droshki

Thank you for helping Billla


Carb is Holley 850 DP


Cam Link: http://www.compcams.com/Cam_Specs/Ca...?csid=204&sb=2

No link for the heads. The only flow numbers specced are
(I) 243 CFM @ .050 valve lift
(E) 188 CFM @ .050 valve lift


The rest on the blower, I dont know...if its like camquest, a lot of that could pertain to turbos. I just have a 144 Cubic Inch B&M Roots type blower. No intercooler. Max boost will be 8 PSI. 10 PSI Blows up engines.

Try just putting in the boost number and see what happens.

billla

Here's my pass. FYI, without full flow data, any simulator is going to give lousy data; I was able to find what looked like reasonable flow data on Stan Weiss' site and made a .FLW file. I made a new .CAM file as well, although the card didn't have both .006 and .050 cam timing - unfortunate.

I don't have sufficient experience with forced induction to make any sense out of this at all in terms of how realistic this is.

Droshki

yea.....

I dont know if its factoring in the boost at all. I would expect a bit more than 429 HP. I would think that you would be able to get close to that with a well built NA 383, dont you think?

According to my Holley brochure here....their complete systemax package (heads, intake, cam) is supposed to produce 425 HP (with 350 CID @ 9.8:1), and thats without even stroking or blowing it.....



Thank you for taking the time to try it though. One of the disadvantages of living in a small beach town like here, is the lack of availability of dynos and such.

billla

My take is that it is factoring in the boost...but the heads are simply too small to support those power levels. For the SysteMax, is it designed for boost?

The cam looks a little light in lift as well - the heads are flowing well past .500 lift...

gkull

You have tiny heads, cam, and blower. The 144 supports under 500 hp driven near it's max rpm. With 383 ci it might not even ever get to 7 psi.

HERE is what CHP had to say

Big or Small?
"Since each motor is different, it's hard to generalize how much power a blower will add, but here are some basic points of reference. Our smaller blowers on a stock small-block Chevy running 6-7 pounds of boost will result in an increase of approximately 100-120 hp. Add a mild blower cam and a larger carb, and you can expect a typical small-block to produce anywhere from 360 to 400 hp. With a good set of heads, you can reach 440-470 hp. Upgrading to a larger blower such as a 6-71 could push the output to well over 500 hp. It's important to understand that an engine does not know what size supercharger is bolted to it. The boost produced by the blower is a bigger factor than the actual size of the blower. So the estimates above are somewhat typical of any Weiand blower. An important characteristic worth noting is that at low rpm, smaller blowers typically produce more torque than bigger blowers. Conversely, at high rpm, larger blowers produce substantially more power than smaller blowers." -Jay McFarland

Droshki

Hmmmm......

No, the sytemax heads are not specifically designed for boost. What is "tiny" about them? Their flow? It was my understanding that this was not too critical since with boost, well, your getting lots of air into the engine pretty much no matter what. It would seem to me that even crappy heads+boost would be better than or at least equal to, very good flowing NA heads, atmospheric pressure being 14 PSI. (Also I dont see new heads being in the budget here, with the need to buy new headers and side pipes.)

Both Comp and Crane specifically recommended not going with "too much" cam or I would lose the bottom end power. This Comp cam is very similar to what Crane recommended. Don't forget that I am using 1.6 roller rockers (since that is what I have here from the old engine). I know that's not night and day, but it does change the actual lift at the valve from .502/.520 to .536/.555. Cam card also specifically states "(for use) with 125+ Nitrous system or small supercharger"

I am surprised to see gkull say that he thinks I wont make 7 lbs. With a fresh blower belt on my 350 engine, I was hitting 10 lbs. (Ask me what happened to that engine), and by my calculations 383 displacement is only 9.4% larger (actually, 7.8%, since it was a 355).

Please dont take anything I say as disagreement or argumentative. I am just pretty clueless and rather disappointed with those numbers. The setup (with a smaller cam) worked very well on my old 350, still making power when the rev limiter hit at 6K RPM, so I figured just bumping to 383 and bigger cam would be a no-brainer.

I welcome further advice (and a free set of new heads )

billla

In the same spirit, recognize that we're not trying to second guess you as the designer...but you asked

You're seeing the boost certainly in the torque curve - again, I don't have the experience to offer any insight here into if that's what you should see.

The Holley heads flow minimally better than stock GMPP Vortecs, so IMHO they're not up for the task. When using forced induction or spray, the engine has to be built to support the ultimate power level it will deliver; if you were looking for 500HP, then you need more capability in the heads and cam. Power without the blower was 385HP@5000 RPM and 431TQ@3500 RPM...a little over 1HP/CID and about what I'd expect from this level of build based on my experience.

That's my $.02 - but again my experience here is limited to bolting on a few Magnachargers and one brutal turbo experiment

Droshki

Well....Ok....then....

If anyone uses that "leaving it on the table" phrase I am going to poke my eye out, but then what are suggestions for more appropriate cam/head numbers?

billla

I'm really out of my element here, but going to a set of Brodix IK200's brought us up to 445HP@6000 and 485TQ@3500. Stepping up to a set of AFR 210 Comps takes us to 509HP@6500RPM and 490+TQ from 3500-4500 RPM.

Maybe a better question might be what power level do you want, and where in the RPM range do you want it?

jpatrick636

I ran what you gave us through my Performance Trends program. I have copied some of the programs analyze features below. What I see is an engine that is running out of breath. It's either in the heads or the super charger. I will run some more analysises and get back to you.


Analysis Report for Street/Strip Engine with Desired HP Peak at 6000 RPM

Peak Tq =470. @ 3500 RPM 1.23 Ft Lbs per CuIn
Peak HP =410. @ 5500 RPM 1.07 HP per CuIn

Maximum Tq/CuIn is 1.228 Ft Lbs/CuIn.
This is somewhat high, indicating good performance, but will
produce high cylinder pressures and temperatures.


Maximum Exhaust System Backpressure 'Exh Pres' is .2 PSI.
This is low for a street/strip vehicle with a full exhaust
system. This is simulating either an extremely free flowing exhaust
system or open headers. This may be illegally loud for the street.


Overlap Flow Area 'Overlap Area' is 10.1 Sq In * Degrees.
This is Very high for a supercharged or turbocharged engine.
Although the Engine Analyzer may show better performance with this
amount of Overlap Flow Area, you may encounter other problems from
'short circuiting' where fresh air/fuel mixture is forced out the
exhaust without being burned.

You can reduce Overlap Flow Area by increasing the Centerlines.


Maximum Volumetric Efficiency 'VE %' is 117 %.
This is somewhat low for a turbo/supercharged street/strip engine.
Typical turbo/supercharged street/strip engines have VEs of 130-180%.

Volumetric efficiency is the best measure of an engine's air flow
capability at a particular RPM, which is critical for high torque
and HP.
Most all engine specs affect VE and the RPM where VE peaks.
However, for turbo or supercharged engines, the amount of boost and
the RPM where boost peaks has the largest effect. This is deter-
mined largely by specs in the SUPERCHARGER


Maximum Fuel Flow 'Fuel Flow' is 302 lbs/hr GAS.
This is equal to 51.6 gallons per hour of fuel flow.
For an injected engine with one injector per cylinder, you will require
at least 38 lbs/hr injectors.


Mechanical Efficiency 'Mech Eff' is 65 %
at the current Peak HP RPM of 5500 RPM.
This is somewhat low and represents a real power loss in this
engine's current operating range. This can be improved by paying
close attention to details in the Short Block Specs menu, or
specifying a more efficient or 'better matched' Supercharger.
'Better matched' means changing the supercharger size or Belt Ratio
so the engine's most efficient operating RPM occurs at the super-
chargers most efficient operating RPM.

Mechanical Efficiency can be improved by:
- Better matching the Supercharger size or Belt Ratio to
the engine if the engine is Supercharged


Your 'Desired HP Peak RPM' you entered for the Analysis Report (6000)


The Maximum Average Piston Speed 'Piston Spd' is 4063 ft/min
at the Performance Calculations Maximum RPM of 6500 RPM.
This is EXTREMELY high (if you want to run this entire speed range),
requiring light, high strength reciprocating components.

A street/strip engine should limit Piston Spd to a range of 3000-4000
ft/min. However, even to run at 3000 ft/min or higher, you will need
'better than production', high quality reciprocating components
(connecting rods & bolts, pistons, etc.).


The % Exhaust to Intake Flow Capacity 'Total Exh/Int %' is 68.2 %.
This is Very low, and indicates you could improve performance
by improving exhaust valve flow and exhaust cam profile. A 'rule of
thumb' is to design supercharged or nitrous oxide engines for around
85% EXH/INT flow capability.

To increase Total Exh/Int %:
- Increase the Exhaust Valve Diameter and/or Valve Flow Efficiency
- Increase the Exhaust Duration, Exhaust Tappet Lift and/or Exhaust
Rocker Arm Ratio


Estimated Idle Vacuum 'Est Idle Vac, ''Hg' is 8.8 ''Hg.
This is somewhat low, and will likely NOT idle well or provide
enough vacuum to run vacuum accessories for an engine which is used
occasionally on the street.

To increase idle vacuum, reduce cam overlap by specifying a lower
(possible negative) Intake Open @ .050 and/or Exhaust Close @ .050,
larger Centerlines or smaller Durations in the Cam/Valve Train menu.

gkull

My experience on 144 weiands is limited to two cars. One being a vette drag racer who had changed pulleys to run the blower near it's max 14,000 rpm. and it couldn't get much over 7psi at sea level on a good air day in a 355 ci. I will explain why.

I thought that you were going to go buy this stuff. I did not know that you had it.

The Holley heads are low flowing and if you were getting 10 psi it is because you had such a bottle neck to flow with a small cam and heads. So if you use the same cam and heads from a 355 and stroke the motor to 383 you would only see a marginal drop in PSI because you have not increased the flow. HP would also be the same but at a lower rpm. Tq would go up as a function of the ci increase. Bigger cc ports flowing a higher amount of air will not allow the PSI to rise because more of the blower air is going through the motor.

Same thing with a small duration and lift cam. As rpm rise the time from open to close can be only thousandths of a second. More duration keeps the valve open longer to fill the cylinders at higher rpm. So again more flow through the motor the less boost psi

Valve over lap is what causes the reversion into the intake. So blower cams should have 112 - 114 Lobe separation.


So anyway the 144 weiand drag motor was kind of a bust because it can't flow enough air and the Vette owner added a 175 hp Spray plate under the 850 carb to get it to do good 1/4 mile times. after a couple years he got smarter and went with a 540 ci N/A

Droshki

Wow. Good stuff.

Im going to have to read this a couple of times.

I was hoping for at least 550 Hp attained at less than 6K RPM, but I'm thinking I could probably spin the motor a little faster than that with all new, forged stuff. (I am going to bigger valve springs and such to accomadate the new cam.) I have 3.73 gears and had no problem geting to 6K RPM before. I had to watch the tach and shift before the rev limiter hit, the motor had no trouble spinning up that far..

But, yes, this basically a re-hash of my 355 motor. I'm moving to a 4 bolt main, stroking it, new rotating assy, and a bigger cam then before, but old heads and blower. I suppose these heads were great when they first came out, but apparently nothing special now. Id love to be able to afford heads too, but 1) My old hookers were rusty as heck so theres a new set in the budget and 2) I am king of planning on a new tranny, cuz I am suspect about a TH350 at these levels. Even though its a B&M built 350, its far from new. Also, although I do love this tranny, a 4th (OD) gear would make this car a little more practical.

What happened to the old motor is that one day I threw the supercharger belt. Up until that point I had been getting 6-7 PSI very consistently. When I installed the new belt and tensioned per the book, I was now getting 10 PSI. Which was great, but in the back of my head I was going um....that seems like a lot, and about 2 weeks later it broke the top corner off of a piston, detonation one would suppose, the only knock sensors being the ones on the sides of my head.

Droshki

Billla (and others) when you say the heads are "too small" you mean ????

Runner volume? Never mind , I've been reading. I see now that while I have good heads, what I need is GOOD heads, with more port volume and combustion chamber volume.

Again, I dont know if new heads are in the picture. I would hate to buy them and then throw the tranny out of the car.

Also, this:
"will likely NOT idle well or provide enough vacuum to run vacuum accessories for an engine which is used occasionally on the street."

Worries me, as after all this is just a street car and not a race car.




Maybe I should have just put a new set of pistons in my old engine and spent my money on heads instead. Call me naive, but I was not aware how fundamental the heads were to HP generation; I thought the answer lay in displacement. Yes, yes, I know now that I have to consider EVERYTHING.....

By the way, I found some more complete flow numbers if it will help the simulation:

LIFT I E
.050 38 28
.100 66 53
.200 130 92
.300 184 122
.400 222 148
.500 242 172
.600 252 187