Sti 05 340 bhp put a full 3" on and oh my god!!! Put foot down!!! Waiting waiting waiting then go!!!!!! Why is this? Do I need another map?? Had full de cat on before but only 2.5"

 

less back pressure on turbo get it mapped again or if all ready mapped get it tweaked

 

Oh the joy!!!! another map

 

Looks like Duncan's popping round soon then

 

I would suspect you have VF35 and you are put 3" exhaust without the remap/tweak.
What extra you are put on car without the tweak/remap?

Jura

 

Harvey 18g fully de cat green panel filter 3 port and Racedynamix map

 

Had similar thing, putting a 3inch on and a bit more laggy, but made more power through the range.

 

Wow matey and you are driving like crazy without the tweak of these fitted parts.
I would recommend drive off the boost until remap/tweak,you can cause more problems than normal.
Contact in your interest(for safety reasons and performance too) soonest as possible Duncan if he does your first map.



Jura

 

Smaller Turbo?

 

Jura
All of the above mods have been mapped already by Duncan (Racedynamix) only thing is the 3" straight through system previosly 2.5" system.. So don't know why car feels so different

 

It's the maths! Pie r squared.
2.5 = 19.6 sq inch
3.0 = 28.3 sq inch

So you have in effect halfed back pressure, by increasing the area by nearly 50%.

See 1/2 inch does make a difference - at least that's what I've been told.

James

 

2.5" = 4.91sq in.
3" = 7.07sq in.
The % increase in area is about the same, though (44%)

I think you took the diameters as the radius!
JohnD

 

On a turbo car a free flowing exhaust is desirable. ie no back pressure.
A 2.5" exhaust is good to 400+ bhp.
Did you do anything else apart from fit the exhaust?
Could you have a headers or uppipe exhaust leak?
What make of exhaust and downpipe?

 

Those are my thoughts too Harvey - will be checking this out with craig next week if we can get diaries together.

 

The system is a one piece made by Alan Jeffrey for big fud wr1. I bought it off him last wk it's a awesome exhaust and sounds lovely and at the same time not to loud... Yeah Duncan appreciate your help when u can mate really want to sort!!!!!
Any other advice would be lovely
Harvey I'm saving for your headers and up pipe and the fuel to get to u as I live in Mansfield
Cheers again chaps

 

You got me thinking now. According to the laws of physics less back pressure on a turbo should increase efficiency. Therefore spool should be faster for the same mass of exhaust gases. Sounds like cylinder head/manifold velocities are slower so you have made it more cammy off boost. Or am I getting this completely wrong?

 

That's just mathamatical bollox to me!!!! lol

 

Just get in touch as and when you are ready. Chesterfield is about 100 miles and M18/A1M is quickest-shortest route.

 

Will do mate and thanks