Tuning a stock fox.?

[FoxBodyNick]

lmao at 80mm.... WTF!!!!! no no no no no.... mike you know this... the idea behind the mass air flow being in the fender with the power pipe is thought to help with throttle response...so mostly you will see that and driveability improvements but without an AM cam i dont see much of a gain if any.... mike if anything you shouldnt waste your money on MAF and TB until you get HCI that can support it...dont waste the money matching those to your setup..... your wanting to see what it can do with stock parts, and upgrading to a maf and tb that is too big will result in a loss of velocity and also resolution... these mafs change the signal to a point grid... the computer will only be able to read a section rather than the whole signal if that makes sense.... someone correct me if im wrong or disagrees. i think 1 5/8 LT headers would do it. change the 2 chamber chokemasters and see how the damn thing runs....

[TENGRAM]

He's not gonna have an issue with air velocity with 20+ inches of constricted intake runners.

[91CoupeMike]

1 3/4 seems on the large side, I'd go 1 5/8 for stock parts.

[FoxBodyNick]

He's not gonna have an issue with air velocity with 20+ inches of constricted intake runners.

lol true true.

[majorownage]

lmao at 80mm.... WTF!!!!! no no no no no.... mike you know this... the idea behind the mass air flow being in the fender with the power pipe is thought to help with throttle response...so mostly you will see that and driveability improvements but without an AM cam i dont see much of a gain if any.... mike if anything you shouldnt waste your money on MAF and TB until you get HCI that can support it...dont waste the money matching those to your setup..... your wanting to see what it can do with stock parts, and upgrading to a maf and tb that is too big will result in a loss of velocity and also resolution... these mafs change the signal to a point grid... the computer will only be able to read a section rather than the whole signal if that makes sense.... someone correct me if im wrong or disagrees. i think 1 5/8 LT headers would do it. change the 2 chamber chokemasters and see how the damn thing runs....

A 4.6 4v flows less air at idle and takes an 80mm. No idle issues from the "reduced" resolution. I honestly don't know if a stock maf would be a restriction.

Air velocity and runner length are not related. lol

[FoxBodyNick]

A 4.6 4v flows less air at idle and takes an 80mm. No idle issues from the "reduced" resolution. I honestly don't know if a stock maf would be a restriction.

Air velocity and runner length are not related. lol

4.6 heads flow more than e7 heads (maybe I-150-160cfm/E-120-125cfm with e7s) different sized mafs are used on these motors. an 80 mm or bigger would be way too big. you can question the resolution being reduced but you might wanna do more research on 5.0 pushrod motors before you give advice to put a 80mm maf on a stock HCI motor... theoretically the stock maf is a restriction... but like i said above, there is no point in really changing that just to sell it and lose money when he gets heads for the thing...

oh and what i believe he meant was the size of the runners on a stock intake will bring the velocity back up due to the small diameter... atleast thats the way i was thinking...

[TENGRAM]

Air velocity and runner length are not related. lol

You might want to review the Moody diagram...

[FoxBodyNick]

You might want to review the Moody diagram...

[Z06killinsbf]

1 3/4 seems on the large side, I'd go 1 5/8 for stock parts.

Read through this please.

http://sbftech.com/index.php/board,64.0.html

[FoxBodyNick]

from what i understand with too large of header diameter and midpipe diameter you will be slowing down exhaust flow. Theoretically you want the exhaust moving as fast as possible. This goes back to the velocity being higher through a smaller diameter tube (to an extent of course). I dont think the e7s can put out enough exhaust to keep up with the pulses needed in the exhaust to keep it flowing to benefit at a 3" exhaust system.

i am unable to read that tech site right now.. wish i could. if you could correct me if i am wrong. =)

[Z06killinsbf]

i am unable to read that tech site right now.. wish i could. if you could correct me if i am wrong. =)

It's more of a discussion over numerous pages with facts and theories thrown in. You really have to read through to understand. I'm too dumb to summarize it.

But here is one post:

Velocity should not be used in arguments for the exhaust past the collectors or turbos. That only needs to apply forward of those.

That and, Joel, bingo, the real big key is tuning. Almost every example from everyone always excludes tuning done on each combination. People do not comprehend that the exhaust is part of the entire combination.

So many people now talk about exhausts of PCM controlled engines. The exhaust affects the best needed air and fuel. Opening up the exhaust leans the mixture, which doesn't help most vehicles. It's hard for people to grasp that if they swap 3" exhaust in place of a 2.25" exhaust, that they must retune the PCM to realize the potential gains.

Cross overs, who has them, likes or hates them, or cannot tell any difference? I see the "H" as more structural than anything else. The "X" is a novel idea, but it does force one exhaust mass into another, that's not ideal. I imagined the best 20+ years ago, seeing 360 degree headers for the first time. Take two pipes side by side, split the flow in half of each(reverse collector), one of each goes straight back, one swerves slightly over and up/under to get parallel to the other's pair pipe, and the four rejoin as collectors, no restrictions splitting or joining. That would reduce restriction from each bank, but it wouldn't quite scavenge like a header. The purpose of a collector should be to somehow efficiently get part of the flow from one bank to the other bank. The idea is to take advantage of the entire exhaust beyond the cross over, for each bank.

Past the header collectors, you want as little restriction as possible. The bigger anything past that, the more air gets out of the engine, and more fuel can go in(retune).

Huge subject, please for the most part keep it on the exhaust behind the collector or turbo, as Joel intended.

[Diabolic]

The exhaust size should be dictated by the timing events of the valves. This is determined by the timing events ground into the camshaft. What you really should do if you want to stick to stock parts is to actually degree the camshaft. They once you accomplish that you can experimet with advancing and retarding the camshaft. I would then contact Buddy Rawls over on the Corral and have him run the Pipemax program based off your exact combination and camshaft installation to determine the optimum Primary tube diameter as well as the rest of the exhaust. You wanna suprise a lot of folks, then don't rely on luck, take the science to it.

As far as the MAF or intake tract goes, the improvement people see from a larger MAF meter with stock E7 heads is primarily due to the fact that meters that are "adjusted" for bigger injectors, or even stock 19's lean out the AFR. Instead of a larger MAF meter and Powerpipe, I would invest in a LC! wideband with gauge, Moates Quater Horse so you can datalog, and EECAnaylzer so you can input your datalog information and let the program refine and calculate the correct MAF transfer table.

[FoxBodyNick]

good info

[91CoupeMike]

Hmm.. I have a lot of reading to do.

Thanks for the information!!

Keep it comin..

[majorownage]

4.6 heads flow more than e7 heads (maybe I-150-160cfm/E-120-125cfm with e7s) different sized mafs are used on these motors. an 80 mm or bigger would be way too big. you can question the resolution being reduced but you might wanna do more research on 5.0 pushrod motors before you give advice to put a 80mm maf on a stock HCI motor... theoretically the stock maf is a restriction... but like i said above, there is no point in really changing that just to sell it and lose money when he gets heads for the thing...

oh and what i believe he meant was the size of the runners on a stock intake will bring the velocity back up due to the small diameter... atleast thats the way i was thinking...

The length of the runner will not change the velocity of the air through the runner, much less the air flowing through the maf.

Cross sectional area governs the velocity given a certain flow rate.

I guarantee a 5.0 flows more air than a 4.6, at idle. It may or may not flow more at higher rpms, but that is irrelevant for the arugment. The the head flow is insignificant factor (will increase the overall flow rate by a little bit, but a larger displacement will dominate the more cfm's)

.2 liters per revolution is a big difference.