New Heads/Cam or Nitrous???

#21
Thanks Tom. I'll be taking everything apart in the next 2-3 weeks and sending the intake to you.

For everyone else....I know the cam is too small and heads aren't exactly ideal for a stroker but at this point I think I'm just going to work with the intake and tb. I might consider retarding the cam, but I do know that geometry of the pushrods is dead on. My builder ordered the pushrods last after he measured for the exact size. I don't know much about valvetrain set-up but I remember him saying he didn't have to shim anything, if that makes sense.

So this round of mods will include...

-Port Performer Intake
-Accufab 75mm Fox Throttle Body
-4" Custom CAI
-90mm Lightning Meter
-30lb Injectors
-255 HP Pump
-Retune

And even though I said I wouldn't do engine work and nitrous, since I'm not spending money on the heads or cam, if I come across a good deal on a complete kit I might consider it in the spring time.

Thanks for you help guys and if you see anything to comment about on this parts list let me know

Dave
 
#22
I think the TB is gonna be a little big for the heads. and the lightning MAF can be tempermental since the sample tube is way off to the side (usually better for supercharged). But yeah, open up that intake! :nice:
 
#24
I got several things to say about the cam retard thing :D

You should be able to shift the power band up a little by doing it :nice:

Doing that would not throw off your vt geom at all :nono:

I can only speak from experience with old school flat tappet cams but with them, a change of only 2 degrees would not do a whole lot. You usually had to go with around 4 degrees to make much difference. So ... take that for what it is worth as things might be different with these newer roller cams with their faster ramp rates and all :shrug:

Another thing about doing the cam retard thing is ..........

If you already got the intake off
and
tear down the front of the motor for the retard thing .........

You might as well just slip in a more suited bump stick ;)

Of course it would cost more :)
but hey
Its so easy for ME to spend YOUR money :rlaugh:

Grady
 
#25
I think I'm just gonna see where the intake and tb get me. Cause like you said Grady if I tear down the front of the engine to retard the cam, I might as well put another cam in. But this weekend I'm going to see my grandfather, if any money comes out of it maybe that will expand my budget and I can dive into the heads and cam. But I know one thing, I want the car ready for the first day of nice weather this spring. I only put about 1500 miles on it this year and I have 5000 miles before I need emissions testing. It's a street car and I plan on having it on the street a lot this upcoming year.

Any more opinions on the tb and maf choice?
 
#26
Black95GTS said:
How is the throttle body going to be too big for the heads?

Adam
Click to expand...

well, the performer heads flow better than stock, for sure, but if you open up the intake (porting) and install a larger throttle body, but leave the narrow head ports in, that becomes your greatest restriction. So that is how a 75MM throttle body would be too big for unported performer heads.
I think it works like this: If the tb and intake can move large volumes of air, and the head's aren't up, they have to have increased velocity and low manifold vacuum. It makes for an inefficient motor.
 
#27
TheRedBlur said:
well, the performer heads flow better than stock, for sure, but if you open up the intake (porting) and install a larger throttle body, but leave the narrow head ports in, that becomes your greatest restriction. So that is how a 75MM throttle body would be too big for unported performer heads.
I think it works like this: If the tb and intake can move large volumes of air, and the head's aren't up, they have to have increased velocity and low manifold vacuum. It makes for an inefficient motor.
Click to expand...

Do you have anything to back that up with? Math or dyno results?

http://forums.stangnet.com/showthread.php?t=579407&highlight=grn92lx

Grn92LX is highlighted because I remember his name being mentioned in the thread.... he is one of the few that agrees with me when it comes to putting "too big" parts in. Ernan picked up around 20rwhp from going from 60 to 75 on a 302. I can imagine a similar results going from a 65 to a 75 on a 331. Providing the performer is ported to accept 75mm.

Adam
 
#28
Black95GTS said:
Do you have anything to back that up with? Math or dyno results?

http://forums.stangnet.com/showthread.php?t=579407&highlight=grn92lx

Grn92LX is highlighted because I remember his name being mentioned in the thread.... he is one of the few that agrees with me when it comes to putting "too big" parts in. Ernan picked up around 20rwhp from going from 60 to 75 on a 302. I can imagine a similar results going from a 65 to a 75 on a 331. Providing the performer is ported to accept 75mm.

Adam
Click to expand...

yeah I dig what you're saying, and I don't have any math up right now. Keep in mind though, that the trick flow heads flow better than the edelbrock performer heads. That is a number I do definately have lying around somewhere.
 
#29
95strokerPSU said:
I think I'm just gonna see where the intake and tb get me. Cause like you said Grady if I tear down the front of the engine to retard the cam, I might as well put another cam in. But this weekend I'm going to see my grandfather, if any money comes out of it maybe that will expand my budget and I can dive into the heads and cam. But I know one thing, I want the car ready for the first day of nice weather this spring. I only put about 1500 miles on it this year and I have 5000 miles before I need emissions testing. It's a street car and I plan on having it on the street a lot this upcoming year.

Any more opinions on the tb and maf choice?
Click to expand...
i think 70mm is right for your setup. here's why:

when the intake valve shuts, it causes an air pressure wave to be reflected back thru the runners into the opening between the thrttle body and the beginning of the runners. that wave bounces back and forth about 3 times while the valve is shut. the idea is to open the valve at the precise moment just before the wave reaches the valve on the 3rd reflection and close it before the wave reflects off the bottom of the piston. the shorter the runners, the faster the wave bounces, hence the higher the target rpm.

the higher the air velocity, the stronger the waves. the stronger the waves, the more air gets into the cylinder, if the valve timing is correct of course. that is how nascar engines actually achieve a volumetric efficiency of over 100%.

so velocity, along with a matching cam and intake is what makes the power.

my builder taught me this stuff ... :nice:

this is why my builder recommended 75mm for my setup. it is also a street car and i have an rpm intake. but mine is 80 more cubes than yours. that is why i think 70mm would be right for you.

whatever you do, make sure the t/b, elbow, and intake are all the same.
 
#30
Black95GTS said:
Do you have anything to back that up with? Math or dyno results?

http://forums.stangnet.com/showthread.php?t=579407&highlight=grn92lx

Grn92LX is highlighted because I remember his name being mentioned in the thread.... he is one of the few that agrees with me when it comes to putting "too big" parts in. Ernan picked up around 20rwhp from going from 60 to 75 on a 302. I can imagine a similar results going from a 65 to a 75 on a 331. Providing the performer is ported to accept 75mm.

Adam
Click to expand...

Of course they don't have any proof to back it up, they're going by hear say from crap they read on the internet. Ernan's results show REAL world PROOF!

The 75mm is the ticket for this guys 331.

A 351 based stroker needs nothing smaller than a 90mm tb. PERIOD!
 
#31
Grn92LX said:
Of course they don't have any proof to back it up, they're going by hear say from crap they read on the internet. Ernan's results show REAL world PROOF!

The 75mm is the ticket for this guys 331.

A 351 based stroker needs nothing smaller than a 90mm tb. PERIOD!
Click to expand...
Really cause I read Accufab saying people are fools (paraphrasing) for buying tb's based on the size of the hole instead of what the entire induction system flowed. Redblur is correct in saying the heads won't flow the extra cfm the TB would try and let in, hell those 800+cfm that Accufab TB flows won't make it passed the intake system. 95strokerPSU do yourself a favor and call Accufab and have the experts tell you what you need.
EDIT: Here the link to Accufab telling folks how the should go about buying a TB (Hardcore50 seems to be down at the moment but read both pages)
http://bbs.hardcore50.com/vbulletin/showthread.php?t=26335&highlight=Cobra+intake
 
#32
Seriously. There are two main concepts in making engines powerful, volume and velocity. Although the two do relate to each other, they are not necessarily dependant upon each other. Naturally aspirated engines benefit more from having high velocity than volume just as supercharged engines require high volumes of air, since the velocity and pressure is already being supplied by a compressor. The most important thing when dealing with induction is consistency of flow. High flow may mean high volume, but low velocity, and it can also mean low volume but high velocity. Flow does not equate to speed. Now, on a naturally aspirated engine, consider the source of the flow from the piston, sucking it's way back. A piston moving up and down in a block without a head will produce negligable flow, add a head on there, and you have flow. On a more specific scale, a cylinder head that isn't huge willl need high velocity to fill the cylinder as the piston moves downward, the advantage of that is what we call swirl. Swirl is where the air rushes into the cylinder at a rate where it keeps wanting to come in, so it spins, it's also called "cylinder filling" it can be done in many ways by valve events. but lets focus on airflow first. If an intake is bigger than (flows more volume than) the heads do, then the entire engine is throttled by the intake runners on the head. The air will only flow uniformly from the throttle body (assuming it's too large) during part throttle, where the air velocity can only accelerate or stay constant. Conversely, if the heads and intake flow better than the throttle body, then there will always be an abundant lack of air (good vacuum) in the manifold, making for more sudden throttle response, since the induction is always "begging" for more air. At this point, the entire induction system is limited by a too small throttle body, where WOT isn't providing enough airflow to efficiently feed the cylinders. If air velocity slows down at the heads, you run into some issues. Issues mean volumetric efficiency. Consider this example, please do not mistake cc's with cfm's. cubic centimetres (head measuring) has nothing to do with flow rates, it just means how much fluid/gasses will fill a given cavity. now back to ctm. Imagine a cylinder head flows about 80cfm per intake runner. At WOT, you will need a maximum of (80*8)cfm, which equates to 640cfm, lets say that is ballpark to GT-40P heads, now lets say a cobra manifold that has fairly smooth ports (early on the casting clock) flows around 620-660 cfm: velocity between the two is farly predicatble and somewhat constant from one area to the other. Now, add a 60mm TB which might flow (for sake of argument) 650cfm... YOu end up with a motor that will flow fairly uniformly throughout the entire induction system, meaning, you can better tune it because what the MAF reads is subject to minimal airflow changes, meaning that an increase of 10cfm will equate to roughly 8-16cfm at the cylinder, making spark and fuel tables much more accurate, emissions readings much more optimized, etc.

On a supercharged engine, the force of air comes from the opposite direction, pressure builds pre-tb, not post. Any concept of velocity is seen as backpressure. High boost does not equate to high power. Buy a 8lb blower and work the induction to 6lb, and you have a hell of a system, considering you greatly reduced backpressure, like in exhausts... During boost, velocity is unnecessary since flow is being provided by a mechanical device. At this point, yo must focus on volume, the maximum amount of particles you can move at at the slowest possible speed, you can afford many more inefficiencies since you have a device that guarantees that you will pass 100% V.E.

I wore out my brain. *opens another alaskan amber*
 
#33
I think the main issue is your cam. Those lift numbers are not letting the air in.

I would think something more like a Comp XE258HR would be better.

CRO-15511 $343.69

Brand: Crower
Product Line: Crower Performance Level 2 Camshafts
Cam Style: Hydraulic roller tappet
Basic Operating RPM Range: 2,200-5,500 RPM
Intake Duration at 050 inch Lift: 218
Exhaust Duration at 050 inch Lift: 224
Duration at 050 inch Lift: 218 int./224 exh.
Advertised Intake Duration: 278
Advertised Exhaust Duration: 282
Advertised Duration: 278 int./282 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.468 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.486 in.
Valve Lift with Factory Rocker Arm Ratio: 0.468 int./0.486 exh. lift
Lobe Separation (degrees): 114
Intake Valve Lash: 0.000 in.
Exhaust Valve Lash: 0.000 in.
Computer Controlled Compatible: No
Grind Number: 218HR224
Quantity: Sold individually.
 
#36
#39
95strokerPSU said:
I just heard back from Accufab this morning and their tech recommended the 75mm throttle body. So I'll be getting one of those as soon I as gather all of the parts for the fox stlye swap.

Thanks for all your help guys.
Click to expand...

:eek: I talked to a guy that knows a guy that is a reputable engine builder that read a magazine article off the internet from 1995... and man, thats way too big! The extra .196 inches from 70 to 75mm will take the car from a torque monster to having a complete loss of "low rpm power." You should take a 55mm TB from a t-bird for the increased velocity.

Seriously though, I'm glad you finally resolved your issues and didn't take all this internet advice at face value.:nice:

Adam
 
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