Need advice to build pair of race muffler slip on’s

[Andy Sheldon]

Chris
Our standard system is the same but with two 5" round mufflers.
The picture has the optional megaphones fitted but they have internal baffles so you get the look but not the noise.
The baffles are removable if you decide you want the noise.
Thanks
Andy

 

[frank beuker]

If it aint Dutch, it aint much...
Its all the same exhaust, just swap slip on's depending on your mood..
https://celeritech.nl/photos/ford-gt40/
Celeritech makes exhaust porn
View attachment 112398

View attachment 112399

View attachment 112400

View attachment 112401

View attachment 112402

View attachment 112404

View attachment 112405

Look up their other photo's for more exhaust porn.. Good inspiration stuff.

Jp did you get a exhaust from them ?

 

[Chris Black]

It looks great indeed ! I really like the twin slim silencers.

 

[Chris GT40 MKII]

Why would you want to change that? Are your neighbors complaining or is it for racing noise restriction?
Just Curious. Because that looks to me like it sounds like it should.

Hi Andy,
this looks like beautiful work. Have you built the same with mufflers ?
Here is a picture of my current setup.View attachment 112396

 

[Ed McClements]

Why would you want to change that? Are your neighbors complaining or is it for racing noise restriction?
Just Curious. Because that looks to me like it sounds like it should.

Since most track events have a 103 dB noise limit, I need to install a pair of race mufflers to replace the straight pipes that are on the car now. I’ve found various 4-1 reducers that can be bought at Summit Racing. There are also various race mufflers offered.
What would you recommend ? Who has some detail pictures of such a build and could post them here ?

 

[Chris Black]

yes, it is because of the noise limits at the racetracks

 

[JP Verweij]

Noise regulations are becoming a real issue these days. GT40's are allready banned from the tracks.
Have seen all GT40's banned from the practice days at Spa 6hrs except one... He had all the time available without issues and ill bet had the time of his live enjoying it..

It doesn't look right but for sure its smart thinking. Slip on system makes the team able to race whenever they can.

 

[Randy V]

Noise regulations are becoming a real issue these days. GT40's are allready banned from the tracks.
Have seen all GT40's banned from the practice days at Spa 6hrs except one... He had all the time available without issues and ill bet had the time of his live enjoying it..
View attachment 113684
It doesn't look right but for sure its smart thinking. Slip on system makes the team able to race whenever they can.

As finicky as Webers are to being properly jetted, I'll wager that they have to run an entirely different jet profile with that exhaust system to still have the engine run right..

 

[JP Verweij]

Probably only have change airbleeds as airbleeds are the ones that affect afr in the top range.

1/3th rpm range = idle jet till main jet fully takes over
2/3th rpm range = main jet till air correction takes over.
3/3th rpm range is where the air correction jet does its job. The smaller the airjet, the richer the mixture.

Float height does contribute a lot to AFR. Fuel pumps that can not cope with the demand on high rpm (like Facet Red Tops) will lower the fuel level in the float bowl at high rpm and so on lean the mixture.

 

[Jos]

Ryan Edwards @ Bicester has done lots of GT40 work - may have some suggestions

 

[Chris Black]

thanks to all for your advices. Here are our mufflers.

 

[Chris Black]

they fitt nicely in the original opening

 

[Chris Black]

the muffling sounds like it will be fine for track days limited to 103dB

 

[Glenn M]

Is that a guess or have you actually measured it Chris?

 

[Chris Black]

Is that a guess or have you actually measured it Chris?

it's my guess, after listening to it and comparing it by ear to my two other racecars, which have been measured at the track.

 

[Glenn M]

I'll be very interested to know how they fare when you do get it measured, especially the static test, which is always the one that 40's struggle with.
Good luck!

 

[Howard Jones]

Chris can you post the source of the mufflers you used above.

Tanks in advance!

 

[Chris Black]

here they are:

2-1/2" Round Muffler 14" Long. Polished Stainless Steel. | Kooks Headers & Exhaust

2-1/2" Round Muffler. Polished Stainless Steel Headers are one of the top performance parts added to vehicles. Kooks Headers improves your vehicles exhaust performance instantly.

kooksheaders.com

 

[Howard Jones]

thanks

 

[Glenn M]

Hi Chris

Just wondered what db those neat silencers measured at?