Dyno for Greatg

[GREATG]

Well as promised I went back to the same dyno after my baseline with a few goodies installed. This chart is the payoff for a Friday night spent under my car.
Stock exhaust vs. 3 inch, no other changes. It is a custom made 3inch from the S pipe elbow back.
As for the theory that a bigger exhaust kills low end torque, take a look at 1500rpm to 2500rpm, there is a gain of about 25 lb-ft.

Original Thread with baseline: http://www.msprotege.com/forum/showthread.php?t=52396

 

[jonnydoe48]

that is a really nice gain. 3 inch turboback or catback?

 

[t3ase]

Nice.

 

[GREATG]

Exhaust Details

These are some pics of my custom made 3inch exhaust with 3" high flow cat, resonator and muffler and stock looking tip, no Check Engine light. It crimps down to 2.5 roughly at the connection to the S pipe. It sounds deep and rumbles on decel. Not many backfires.

 

[t3ase]

Okay, since you brought it up, I have to ask. Since you're going from a 2.5" (2.25?") diameter hole, why use a 3" exhaust?

 

[GREATG]

Engine Room ! More Horsepower !

Next things to go on were the FCD, and the Joe P MBC and the boost gauge.
This is with my 3 inch exhaust, FPR, FCD, MBC @ 13psi, flashed, NGK BKR7E, and here's the kicker, the stock air box pried open (I don't have a K&N). Same shop, same dyno, a little warmer because the shop doors were closed. The baseline is cold IC, first pull, the one towering above it was after a few pulls and with a much hotter IC.
The A/F on the wideband was going nuts. It would start out low around 10.2 to 1. Then at 5000 is would lean out to 12, then at 6000 it would jump to 11-13-11-13. It was a heartstopper. Then we turned the boost down.

 

[t3ase]

Careful with the FCD.

 

[GREATG]

Hot intercooler

Here are some pulls back to back with about 11psi and the air box pried open. The wideband was reading 10.2 till around 5000 then it would lean out to 11

 

[GREATG]

Street Trim

This is what happed with the air box closed after the 180 runs. The boost went down by itself and hp sunk. This is likely what I would make at a stoplight with a warm engine. A/F ratio was more steady with the box closed.

 

[GREATG]

Car on Dyno

Some pics at the dyno

 

[ARunto]

when you dynoed are you dynoing on pump gas or race gas on the high psi runs? any detonation? i found my motor to detonate at 9psi on pump gas. what gap are you running on the spark plugs?

-Alan

 

[GREATG]

Installing the 3 inch

Fun on a Friday night:
The install took about four hours, removing the stock was a slut even with WD40 everywhere. The O2 sensor did not want to budge. Also a pic of the place for the wideband to plug in near the elbow.

 

[GREATG]

when you dynoed are you dynoing on pump gas or race gas on the high psi runs? any detonation? i found my motor to detonate at 9psi on pump gas. what gap are you running on the spark plugs?

-Alan

I was running Sunoco 94 and there was no detonation with 4 pairs of ears listening. I was nervous about it though above 10psi. I saw the hp #s though and said up with you, boost!

 

[ARunto]

what did you gap your sparkplug to?

 

[GREATG]

The thing about the gain stock exhaust vs 3 inch is, the boost level can change. Last year when I got the 3 inch first put on, I was running at 10 psi. Then on the way home from the shop it went up to 12. Last night I wanted to baseline the boost gauge with the stock exhaust, but I couldn't get it installed. I had to wait to do it at the raceshop. I think it was at 6psi for the first run before turning it up, but it was with no MBC on the car. That was the 169.5 run. Then I installed the MBC and started turning it up. So basically if you are Joe MSPer you can expect 22hp out of a system like mine, bolted on with no other changes. That may or may not include a small jump in psi. By the way, the 3inch makes the car way easier to drive smoothly.

The plugs were gapped to .035

 

[jonnydoe48]

Okay, since you brought it up, I have to ask. Since you're going from a 2.5" (2.25?") diameter hole, why use a 3" exhaust?

http://www.vishnutuning.com/news_pvnrt.htm

this should somewhat answer the question, i think. it explains how this can be beneficial and increase airflow.

not sure though. i am still questionable about it.

 

[t3ase]

Thats right, the ideal turbo exhaust system would smoothly taper in the other direction- from smaller diameter (the same size of the turbine discharge outlet) to larger diameter over a short pipe length. The length of the exhaust system would be short enough to minimize exhaust gas friction while long enough to incorporate a suitable horn-shape with a diameter rate-of-change aggressive enough to minimize exhaust back-pressure while gradual enough to keep from inducing boundary layer disruption (when the exhaust flow no longer smoothly flows along the surface of the pipe but instead separates from it and becomes turbulent).

Okay, so how is a 3" immediately after the S-pipe gradual? You suddenly have a 3" opening and the airflow gets disrupted. Instead of the gradual "<", you have "-[:"

EDIT: Looked at the pics again, there is a *small* gradual V. I still don't think a 3" exhaust is needed though and would love to see a 2.5" system put on there for comparison.

 

[MazdaSP]

woah... i wanna see him make those runs with ions cai that supposedly adds 24hp...195 to the wheels with just the flash and fcd mods brings a little joy back into my life, i already have mbc, fpr, and 3inch S-back exaust

 

[GREATG]

And the prize goes to mp5jeff, only 6 hours till the liar, liar, pants on fire calls. Take a look at 5252rpm on every chart there sport.

 

[MazdaSP]

i see the crossings... maybe he was looking at them in red/blue instead of red/red and blue/blue?