This is on a Lotus 7 variant, called a Rotus. Here's a link to pictures.

https://picasaweb.google.com/drsms22/KillerBee1990Rotus

This is a 13B engine with lightweight rotors and lightweight flywheel and a Racing Beat modified Holley 600cfm carburetor with Holley Intake Kit model: 84-92 6-Port.



1. It has good top end power but idles poorly and runs roughly on the street. How to improve smooothness of power delivery for low to moderate rpms?

2. Racing Beat recommends 1. Long primary header - dual-tube connecting pipe - rear muffler(s). (i.e. Road/Race Exhaust System)
2. Streetable Header/Presilencer - y-pipe - rear mufflers.
3. Downpipe/Presilencer - y-pipe - rear mufflers.

I need to get this car quieter, much quieter.

 

This may not be the classiest thing to do, but you could weld in a cherry bomb before the Y or 2 inline after the Y.

 

I'd do an RB exhaust its quiet and will last as long as the car. Well worth the price

 

An RB exhaust won't really work. This is not a first gen chassis. You can duplicate one modded to fit MAYBE. The car is really short so there's not enough room for all that stuff. I have a Maxton which is in the same boat and I'm still working on finding what will work and be quiet. Another maxton owner told me that installing a cat after a presilencer then a magnaflow bullet will end up fairly quiet but with a carb, the cat will clog quickly. I'm trying to get it under the SCCA 95 DB limit. A turbo also quiets things quite a bit but I don't want to go that route for a long time if ever.
Kind of off topic but how does the holley work in hard cornering? My Dellorto sucks in long right corners.

 

the way the holley mounts(bowls left and right instead of front and back) causes stumbling in hard left handers.

 

Yea, Ive started picking up fuel injection parts.

 

I think your best bet, to meat those sound limits, would be a couple of RB presilencers and one of their mufflers. Your options are kind of limited, with the heat tolerance requirements and all that.

Good luck, sounds like a very interesting project.




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