9 replies to this topic

[lachlan1275gt]

Hi,

I am after some suggestions for an exhaust setup on a 1275gt with a "stage 2" ish motor, 286 cam, 45 DCOE, lightened flywheel, bored out, etc etc

 

Currently I run a RC40 single box, which is lovely. However I have a problem that most would likely not see as a problem, the induction noise from my carb is significantly louder than the exhaust, which means while driving I never hear any noise from the rear.

 

As much as I love the induction noise from the carb, I feel like I should really have more exhaust noise considering the work I have put into the engine. The RC40 just seems oddly quiet when compared to some similarly specced cars I have been around at events.

 

For some context I use my mini for joy rides on the weekend / sunny days and autocross / track days, I am young and have no problem with having an obnoxiously loud car. As an example, as soon as I have a reason to drop the gearbox (the only stock major part) I will likely go for straight cut gears.

 

Suggestions? Ideally keeping as much as my original exhaust system as possible.

 

Ta

[nicklouse]

Suggestions yes lose the carb.

 

from the brief spec you have listed I would not change the RC40.

[Gaz66]

My personal opinion.....
Weber induction roar.... Can't beat it 👍
Straight cut everything... 👍
RC40....👍
All this adds up to 😁😁😁😁😁

[imack]

I replaced my 1 3/4" single box RC40 with the 2" Maniflow RCM historic race system. Louder than the RC40, but it not cheap, and you'll need a large bore manifold with a 2" collector.

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[Shooter63]

Just put an engine sounds app on your phone and turn the sound system up, that way your happy and your neighbours won't want to kill you:)

Shooter

[coopertaz]

had a janspeed single box on 1380 nice rasp to it. for noise playmini large bore is prob. loud enough or large twin dtm style. for straight cut everything would avoid doing drop gears if used on road but love the atraight cut whine my 1380 had

[nicklouse]

I see a mention of a 2” bore exhaust. Way too big for a 1275cc. If you go too big you lose gas speed and power.

 

RC40 single box on a 1293 296 and IDA had the rolling road think it was a 1380.

 

any carb that has an opening direct to the head makes too much noise just like a SU with a pancake filter.

[bpirie1000]

1.3/4" would be better in my opinion.

[lachlan1275gt]

Turns out I DON'T actually have an RC40, it just looks kinda like an RC40 but it was a random muffler that was hanging around my Dads shed.

 

I have an LCB, 45mm outer diameter all the way up to the muffler, so now just need to decide what to put on the end ... Hmm, cherry bomb, but less loud??

[lachlan1275gt]

Suggestions yes lose the carb.

from the brief spec you have listed I would not change the RC40

What? You suggest losing the carb over slightly modifying the exhaust? That would be a pretty significant power loss, considering the work I've put into the engine.
By 'losing', I assume you mean changing to a smaller carb. In the past I ran a dellorto 40 dhla which still had induction noise (but no where near as much as the weber), which was significantly slower at full throttle even when properly jetted.

Edited by lachlan1275gt, 12 May 2024 - 10:41 AM.