67mustang302

You can port stock heads all you want, they'll never be as good as an aftermarket design. If you want to retain a stock look there are still a few companies that makes cast iron heads.

my77stang

you could do early 351w's or GT40's and they would look stock, or world products heads, or some of the best heads you can buy right now are RHS and they make em in cast iron.

also, ford / shelby had "cobra" intakes that were aluminum and looked strikingly similar to the performer rpm (i suspect they are the same damn casting) or you could grind down the name on the intake and paint it with ford blue or cast iron color.

jcomp

Analysis Report for Street/Strip Engine with Desired HP Peak at 5000 RPM



Peak Tq =258. @ 3500 RPM .89 Ft Lbs per CuIn

Peak HP =207. @ 4500 RPM .72 HP per CuIn



Maximum Exhaust System Backpressure 'Exh Pres' is 2.4 PSI.

This is typical for a street/strip vehicle with a free flowing,

full exhaust system. To simulate open headers, select the

'Open Headers' from the Exh System Type combo box.



Typical ranges of Exhaust System Backpressure are listed on page

32 in the User's Manual. You can lower the Back pressure by

increasing Exh System CFM Rating in the Exhaust Specs menu.

Lowering the Exh System CFM Rating will simulate a quieter, more

restrictive exhaust system. Most dyno tests are done with open

headers, which are simulated by selecting the 'Open Headers' from

the Exh System Type combo box.





Maximum Intake Manifold Vacuum 'Int Vacuum' is 1 'Hg.

This is somewhat high and is limiting air flow and HP.



Reduce Int Vacuum by specifying a larger Carb-T/B CFM Rating in the

Intake Specs menu. Some classes of racing limit performance by

specifying a small Carb or a restrictor plate. In these cases,

you must try to improve performance with this small Carb CFM Rating

or legally make small improvements in the Carb CFM Rating.





Maximum Volumetric Efficiency 'VE %' is 86.9 %.

This is somewhat low for a 'non-supercharged' street/strip engine.

Typical 'non-supercharged' street/strip engines have VEs of 85-105%.



Volumetric efficiency is the best measure of an engine's air flow

capability at a particular RPM. High VE is is critical to obtain

high torque and HP. See page 73 for a definition of volumetric

efficiency. Most all engine specs affect VE and the RPM at which

peak VE occurs. Generally, engine torque will peak close to the

RPM giving peak VE.





Maximum Fuel Flow 'Fuel Flow' is 142 lbs/hr GAS.

This is equal to 24.3 gallons per hour of fuel flow.

For an injected engine with one injector per cylinder, you will require

at least 18 lbs/hr injectors.



Fuel Flow will only change if air flow changes or if you inject

nitrous. The Engine Analyzer assumes 12.5:1 A/F for gasoline and

5:1 for alcohol (methanol) and 3:1 for 'Very Rich Alcohol' for all

conditions. You can not richen or lean out the fuel mixture.





Mechanical Efficiency 'Mech Eff' is 74 %

at the current Peak HP RPM of 4500 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.



Mechanical Efficiency can be improved by:

- Better matching the Supercharger size or Belt Ratio to

the engine if the engine is Supercharged

- Reducing piston skirt size or piston ring tension

- Minimizing 'power robbing' accessories

- Reducing crankcase windage

- Reducing stroke

- Reducing valve spring loads

- Reducing the engine's operating RPM range





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

does NOT match the 'For Peak HP at this RPM' spec you entered

in the lower right corner of the Running Conditions menu (the

menu containing the Weather Conditions, RPMS to Run, etc.)

Change the 'For Peak HP at this RPM' spec in the Running

Conditions menu to match your 'Desired HP Peak RPM' and

recalculate performance.



Then check the 'Approx Cam for HP Peak' suggestions at the bottom of

the Special Calculations section of the test results. They will

suggest APPROXIMATE cam specs to produce a HP peak at this RPM

with your current cylinder heads. (If you don't see the Special

Calculations section, click on View, then click on 'Show Special

Calculations'. Then click and drag the button on the scroll bar on

the right side of this section down to see all the Special

Calculations, including these suggestions.)





The Maximum Average Piston Speed 'Piston Spd' is 2870 ft/min

at the Performance Calculations Maximum RPM of 6000 RPM.

This is somewhat 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.).



Piston Spd (average piston speed in ft/min) and Piston Gs (peak

piston Gs) are indicators of how severely you are stressing the

engine's rotating components. To lower Piston Spd and Piston Gs,

you must shorten the piston Stroke or design the engine for a lower

RPM range.



Maintaining low Piston Spd and Piston Gs are critical for 'keeping the

engine together'. OVER-REVVING PARTS BEYOND THEIR INTENDED LIMIT IS

UNSAFE FOR THE ENGINE, YOURSELF AND BYSTANDERS.





Maximum Contribution to VE During Overlap 'Overlap %VE' is 0 %.

This is Very low for street/strip engines which typically show

3-8%. Low Overlap %VE will limit Tq & HP and is most likely is caused

by high exhaust backpressure, high intake vacuum, exceptionally poor

intake and/or exhaust tuning or too little valve overlap.



It is normal for Overlap %VE to dip (even go negative) at some RPMS.

You will not be able to eliminate these dips and still maintain high

Overlap %VE at other RPMs. However, you may be able to move the dips

outside your desired RPM band.



Overlap %VE is the amount that volumetric efficiency (and performance)

improves by tuning or is hurt by intake reversion during overlap.

Overlap %VE improves (is a high positive + number) when:



- Exhaust pressure 'Exh Pres' is low

- Exhaust tuning pressure during overlap 'ExTun Prs' is low

(a large negative number).

- Intake vacuum 'Int Vacuum' is low

- Intake tuning pressure during overlap 'In ResTunPrs' is high



The tuning pressures are affected by runner dimensions and somewhat

by cam timing. Review Appendix 5 on intake and exhaust tuning.



Overlap %VE is also strongly affected by the amount of cam overlap. If

the pressures mentioned above are good and the cam has a large

overlap, OV %VE will be high and help performance. If these pres-

sures are good, but cam overlap is low, Overlap %VE will be less

and the performance improvement will be less.





The Intake Runner Velocity 'Int AvgVel' is 305 ft/sec

at your 'Desired HP Peak RPM' 5000 RPM.

This is somewhat high and indicates you will need a larger Intake

Runner Diameter or larger Intake Port Diameter for less

restriction and stronger intake tuning.



For these engine specs, an 'Int AvgVel' of about 250 should work well.

If the 'Int AvgVel' is approximately 30-80 Ft/Sec higher than this,

you will likely improve torque below this RPM, but lose some HP.





The Inertia tuning of this intake is tuned to 4796 RPM,

which is close to your 'Desired HP Peak RPM' of 5000 RPM.

Since this RPM is about where the HP peak should occur, peak HP

should be good. If you specify longer and/or smaller diameter intake

runners, you will likely

silverblue66

Wow, thats a lot of information. Thanks jcomp. everyone has been very helpfull. Thank you all.
Kip

silverblue66

One question, is that at the flywheel or the ground?
Kip

my77stang

flywheel

Gary H

Which stock heads? I'd bump the compression up some, 9.2-9.3-1