Performance Diffierences Between Outward Rolled Exhaust Back

Featuring the flop top fop himself and special guest stars.

Postby sunnyFRST on Tue Dec 18, 2001 4:55 pm

Firstly before you read this thread please note we are not having a laugh and the information below is accurate! - trust me (just the same way as we all trust other people's power claims on the internet)

Just before FezzyTurbo got his new exhaust fitted we laughed about which type he should go for.
Me and FezzyTurbo were in deep discussion regarding the diffierence in Outward Rolled Exhaust Backbox tail pipes and Inward Rolled Exhaust tail pipes.
We wanted proof therefore we took a certain FRST to a rolling road along with 2 exhaust back boxes...... the results were amazing (We were both shocked!)

Inward Rolled Exhaust produced 184bhp on standard injectors and a T3.

Outward rolled Exhaust produced 230bhp on the same engine!

Wow - what a diffierence!
Everyone get your exhausts sorted to 'outward rolled back boxes'.
Me and Fezzie are gonna!

Sunny :wink:
Do you have any idea what 178.8mph feels like in a Fiesta? 2000 lb of pressure per square inch per second pushing back on your face. It feels like god himself is trying to rip the skin off your skull while someone lands a 747 on your chest.
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Postby Fezzy Turbo on Tue Dec 18, 2001 5:01 pm

Yes in deed folks....the truth is there.....

Myself and Sunny were absolutley gobsmacked when we saw the differences, i think it has something to do with the exhaust gases getting a smoother exit with the outward rolled tailpipe.....this means the turbo has less strain and can produce more power.

get them rolled out!!!
Greg : Owner of a FRST for 14yrs

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Postby sunnyFRST on Tue Dec 18, 2001 5:02 pm

even PaulR was with us and can confirm that this is accurate!!!

Sunny.
Do you have any idea what 178.8mph feels like in a Fiesta? 2000 lb of pressure per square inch per second pushing back on your face. It feels like god himself is trying to rip the skin off your skull while someone lands a 747 on your chest.
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Postby Jon ERST S2 on Wed Dec 19, 2001 4:48 am

:rolleyes: :lol:

Was that with or without the Max Power stickers?
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Postby Doc on Wed Dec 19, 2001 5:27 am

I can confirm also, but i thought you would have picked up on this earlier Sunny/ Fezzy??
I came across this a few months back when i read Max Power they stated i should be getting +16 BHP with a S/S exaust, i was only getting around 4 BHP increase!!! :oops:
After looking at this further i came to the conclusion that the inward rolled exhaust was causing fluctuating turbulance on immisions, thus i simply rolled the lip outwards to improve immision flow, hey presto the next trip to the rollers + 25BHP!!!
WOW.
I`m now looking into the inlet side of induction and after removing the Turbo lettering on the cross-over pipe i`ve noticed gains also, i will let you know the full outcome.
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Postby packers on Wed Dec 19, 2001 5:36 am

cool thats wicked.....who would have thought summat so small could make such a difference!!
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Postby Project on Wed Dec 19, 2001 5:50 am

Think Doc's havin' a bubble here ... :rolleyes: :lol:
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Postby sunnyFRST on Wed Dec 19, 2001 6:13 am

It's True...It's True! - I knew no-one would take us seriously! The facts speak for themselves!!!

Sunny Outward is the way to go.
Do you have any idea what 178.8mph feels like in a Fiesta? 2000 lb of pressure per square inch per second pushing back on your face. It feels like god himself is trying to rip the skin off your skull while someone lands a 747 on your chest.
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Postby Project on Wed Dec 19, 2001 6:23 am

Not you Sunny you numpty! I meant Doc - how does the "Turbo" lettering affect the airflow? Is it embossed inside the pipe? Or is he just pulling our chains????

:rolleyes:
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Postby Doc on Wed Dec 19, 2001 6:45 am

The Turbo lettering IS embossed inside the pipe thus causing an induction "rippling" effect, not good! I`m investigating this at the mo, "clean" air = smoother induction = increased power.
:cool:
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Postby Project on Wed Dec 19, 2001 7:34 am

Well fffuuuuck me you guys really *are* nutters!


:grin:
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Postby elm_us on Wed Dec 19, 2001 7:42 am

so the outwards rolled is just on the backbox or the whole system

(does it have to be a s/s system)

(whats backbox?)

:???: :???:
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Postby TrekkieFRST on Wed Dec 19, 2001 7:46 am

It's true that having smooth exaust ports can increase power but with inlet ports if the air and fuel moving in are turbulent it will allow for a better mix of fuel and air thus providing better burn in the engine so I don't know whether it's better smooth and rough for inlet
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Postby Doc on Wed Dec 19, 2001 8:00 am

Trek, thats what I`m investigating!
so the outwards rolled is just on the backbox or the whole system

(does it have to be a s/s system)

(whats backbox?)


Just the backbox, the whole system should be clear of any obstruction.
S/S has a smoother surface and is treated different from frous metals this gives even more airflow so expect bigger gains from S/S
A backbox is the final part of the exhaust system that pertrudes out of the rear of the vehicle. ie. mine is a 4" OUTWARD rolled backbox tailpipe.
Hope this helps:wink:
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Postby elm_us on Wed Dec 19, 2001 8:04 am

ok thats kewl i thought u or people have to roll em them self
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Postby EvilFranky on Wed Dec 19, 2001 8:11 am

STOP TALKING ABSOLUTE B-O-L-L-O-C-K-S!!!!!!!!!!!!!!!!!!!!!!!!
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Postby Robin on Wed Dec 19, 2001 8:26 am

:eek: :eek: i don't belive that, how does having a different desgin tailpipe give such a increase in BHP.
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Postby Project on Wed Dec 19, 2001 8:33 am

Anything that helps you to breathe more efficiently and more smoothly will allow a more effiecient combustion - compare it to human breathing if you like. How much easier is it to breathe out hard with your lips curled inwards over your teeth, and outwards??

And inlet tract airflow needs to be turbulent only after the TB usually - up to that point the smoother the surfaces of the inlet tract, the more fficient and faster the airflow.

As far as tuning goes, these things are really only the icing on a well-tuned cake in the first place. Putting an s/s exhaust and an airfilter on a 1.1 doesn't mean worrying about the above becomes necessary in general terms at least.
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Postby sunnyFRST on Wed Dec 19, 2001 8:41 am

On 2001-12-19 07:11, EvilFranky wrote:
STOP TALKING ABSOLUTE B-O-L-L-O-C-K-S!!!!!!!!!!!!!!!!!!!!!!!!



We didn't believe it also but It's true..It's ture!!

Sunny.
Do you have any idea what 178.8mph feels like in a Fiesta? 2000 lb of pressure per square inch per second pushing back on your face. It feels like god himself is trying to rip the skin off your skull while someone lands a 747 on your chest.
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Postby chumkila on Wed Dec 19, 2001 9:04 am

Thank you Sunny. good timing as im gona bet changing me exhaust real soon! :wink:
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Postby Doc on Wed Dec 19, 2001 9:14 am

AH HA, Theres another trick to squeeze that extra BHP out, polishing the inside of your backbox, no sooty deposits in my backbox distrupting my airflow :wink:
I cant believe these secrets are coming out :oops:
I suppose people would find out in the end :???:
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Postby Paul R on Wed Dec 19, 2001 10:00 am

It does sound like crap.. but the evidence was there right in front of us!
You learn something new everyday :rolleyes:
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Postby EvilFranky on Wed Dec 19, 2001 10:02 am

This has gone on long enough...i'm calling the men in white coats for u boys...

I mean 230bhp on standard injectors! LOL

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<font size=-1>[ This Message was edited by: EvilFranky on 2001-12-19 09:03 ]</font>
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Postby Paul R on Wed Dec 19, 2001 10:05 am

Fezzie has got a Focus RS fuel pump and FSE power boost valve, so i guess he's able to get the fuel through somehow :???:
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Postby EvilFranky on Wed Dec 19, 2001 10:09 am

Paul...stop it, u know thats got nowt to do with it...
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Postby Mike Gurney on Wed Dec 19, 2001 10:20 am

This sounds like it should be reproduced on a dyno for everyone to see the results.

anyone want to do this ??

I wonder what the bhp would do if there was no back box at all.

Over here in Auz they already know about inward rolled exausts and most manifolds and pipes have special outward welded seams to improve hp !!

Mike.


p.s - I would like to say tho that 230 bhp from std injectors just sound very suspicious !!! - who's rollers were they ??



<font size=-1>[ This Message was edited by: Mike Gurney on 2001-12-19 09:29 ]</font>
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Postby Jon ERST S2 on Wed Dec 19, 2001 10:35 am

The rolling road operator was a guy called Max on Power rollers in Peterborough. :wink:
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Postby Jon ERST S2 on Wed Dec 19, 2001 10:39 am

the injectors were taken out and outwardly rolled to increase their flow - that is how they managed to get 230bhp :eek:
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Postby ~Lexy~ on Wed Dec 19, 2001 12:12 pm

If u think about it makes sense really :grin:
just take a moment to think about it. :smile:
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Postby Project on Wed Dec 19, 2001 12:59 pm

I'm still mulling this over, since the maximum bore of the tailpipe on an inward rolled box can still be larger than the overall bore, and yet it can cause these probs, kinda like shockwaves.

Port-matching the zorst ports is done for the same reasons too I guess, but the massive change in power between back boxes could well be attributed to the internal design of the box as much as anything :wink:
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Postby sunnyFRST on Wed Dec 19, 2001 1:14 pm

Why the hell some of you lot not taking me serious!? - this is soo true!
If you wanna joke about it...it's your loss!
Knowledge is power!!!
Everyone else - remember, outward folded exhaust tail pipes are the dogs!

Sunny.
Do you have any idea what 178.8mph feels like in a Fiesta? 2000 lb of pressure per square inch per second pushing back on your face. It feels like god himself is trying to rip the skin off your skull while someone lands a 747 on your chest.
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Postby Mike Gurney on Wed Dec 19, 2001 1:15 pm

Sunny - who's rollers were they ?

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Postby Doc on Wed Dec 19, 2001 1:23 pm

Will your flamer kit not interupt the flow? Try removing it you "may" get over 300bhp :wink:
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Postby sunnyFRST on Wed Dec 19, 2001 1:25 pm

Mike the company that carried out the experiment do not wish to disclose their name.
Doc - It wasn't my car that was the test vehicle :wink:

Sunny.
Do you have any idea what 178.8mph feels like in a Fiesta? 2000 lb of pressure per square inch per second pushing back on your face. It feels like god himself is trying to rip the skin off your skull while someone lands a 747 on your chest.
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Postby Doc on Wed Dec 19, 2001 1:28 pm

Was it Fezzy`s??? Cause that cheeky scamp has took his side stripes off to improve aurodynamics, then sold em to me so i am slower!
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