Tried my different setup, and got a lesson on the "myth of backpressure"

[Oryan02]

How big a shot are you going with on the direct port? What all have you got behind it to support it?

[12secondv6]

Starting at a 150 and maxing out eventually at a 200 shot.

When you say behind it, what do you mean?
Tranny?
Rear?
Tires?
??

[ February 02, 2003: Message edited by: 12secondv6 ]</p>

[StockV6Cam]

I'm sure he's asking what kind of internal mods do you have done to support that large of shot.

[MustangEater8251]

I have done this before, maybe its differnet on a 3.4L but an open Y-pipe I ran a 16.2, added a clogged cat and ran 15.8s.


Normally I can say track results are not the end all sayings, but I am a VERY consistent driver, and a .4 difference is pretty big difference for me.

helel I ran a 15.661, twice in the same night down to the thousandth of a second. [img]smile.gif[/img]

[MustangEater8251]

I would also like to add... I know Magnus got some gains off an open y-pipe, but I can gurantee the average car does not.

[Oryan02]

<blockquote>quote:</font><hr> Starting at a 150 and maxing out eventually at a 200 shot.
When you say behind it, what do you mean?
Tranny?
Rear?
Tires? <hr></blockquote>

Internals mostly. That and what kind of computer tuning are you doing?

[Oryan02]

<blockquote>quote:</font><hr>I have done this before, maybe its differnet on a 3.4L but an open Y-pipe I ran a 16.2, added a clogged cat and ran 15.8s. <hr></blockquote>

What was your MPH on those runs? (respectively)
I'm going to guess that your 16.2 had a higher MPH than the 15.8. Even if the two MPH's are the same it would show that you had more HP on the slower time. (If that makes any sense)

[MustangEater8251]

they were about 1-1.5 mph slower


same as when i ran the car that I posted earlier...


remember my cutout is located in front of my CAT, right off the Y-pipe, not all the way in the back before the rear axle like most cars.

Just posting what happened with my car if you guys have results to prove a different setup works for you, go for it.

open cutout on y-pipe is not ideal for me, and not ideal for 12sec on the dyno. But apparently Magnus swears by it.

Now a cutout back by the rear axle, after the CAT and S-pipe is still getting some backpressure jsut not alot as much as an entire cutout.

I am just saying my car varied, on the same night and actually track prep got worse as the night went one. And my car varied roughly .3-.4 tenths and 1-1.5 mph. Thats a huge difference with me, my times are usually within .05, of each other if I hook every launch. Most theoretical hp calculators would say that was a 30-40 hp difference, but I will be relative and say maybe it affected me buy roughly 10-15 hp.

[ February 03, 2003: Message edited by: MustangEater8251 ]</p>

[12secondv6]

<blockquote>quote:</font><hr>Originally posted by Oryan02:


Internals mostly. That and what kind of computer tuning are you doing?<hr></blockquote>

Internal mods: they will be posted when the engine is done.
Computer tuning, technically I do not need any depending on my set up [img]smile.gif[/img]
I do however have superchips custom tuning to maximize what I use so far.
But I can use a combo of:
Superchips custom tuning
Bigger fuel pump
AFPR
Injectors (not like I'm changing those damn things!!!)
Nitrous and fuel jets

Depending on the results when it is done a DFI system is definately an option.

[Fin]

My 3.4 always seemed to run better with the cutout open than it did when it was closed. Usually by about 1-2mph & a tenth or so.

[MustangEater8251]

<blockquote>quote:</font><hr>Originally posted by Fin:
My 3.4 always seemed to run better with the cutout open than it did when it was closed. Usually by about 1-2mph & a tenth or so.<hr></blockquote>

Where was the cutout located?

[cb1101]

Damn Good question MustangEater. I would also like to know. :D

[MustangEater8251]

I am jsut trying to say a car needs backpressure not that a cutout gives too much.

MY cutout gives a little too much freeflow, since it is directly on the Y-pipe, before the CAT, so its almost exactly like running a open y-pipe, jsut slighlty less free flowing.

[cb1101]

are all cut outs for a 3.4 in the same spot?

Sorry im clueless

[MustangEater8251]

<blockquote>quote:</font><hr>Originally posted by cb1101:
are all cut outs for a 3.4 in the same spot?

Sorry im clueless <hr></blockquote>

you can put a cutout where ever you tell the guy you want it.

Most cutouts on f-bodies are put on jsut before the rear axle, mine is right by the feet of the passenger seat, in front of the CAT