8-into-1 Exhaust
I’m swapping the Ricardo for an Albins ST6-M which is back ordered. Agile Automotive lent me the bell housing and front half of the case from a crashed car for fitment purposes. It’s a lot skinnier than the Ricardo and that got me to thinking… which is always a dangerous thing. I am now trying to mock 8-into-1 exhaust.
Ultima Build
Love this sound!
I’m neutral on the idle sound, but I’d never guess that there’s an LS in there.
Dyno pull
Some forum comments on the build are here.
39 inch primary (as short as possible in this configuration)
The headers are 1.75 stepped at 18 inches to 1.875
The headers are sequenced so that they follow timing order as they hit the collector. So each cylinder is firing into the vacant spot left by the exhaust flow before it.
Not really loud at idle. A bit loud under full throttle but a pleasant to my ears loud.
An article here.
SL-C
The 8-into-1 merge collector has an OD of about 7-1/2”. The Albins ST6-M is a lot skinnier that most transaxles and there is room between the 2” x 2” chassis tubes and transaxle. The starter is on the left side, so it makes sense to put the collector on the right side. The picture below shows an 8” diameter merge collector with, from this view, a counter clockwise firing sequence. The right angle piece to the right of the collector represents the 2” x 2” chassis tube (the perspective makes it look closer than it is). The big question is, “will the axle hit the top of the collector, particularly at full droop?" If not, I think that this is doable.
This of course means that the primaries will be completely asymmetric. The furthest exhaust port is cylinder #1. If cross the #1 primary under the oil at an angle the length appears to be 40”. Not ideal, but I have more than enough power so losing some isn’t a big deal.
Links
Greg Holman (REF Unlimited 928-692-0111)
Very helpful….
If primaries longer than 36”, you want to step. Probably 10-12” for my engine. Start with 1-3/4” for a NA and 1-7/8” for supercharged.
Ultima had a 4” outlet due to fitment. 5” would have been better
Muffler should be as close to the exhaust tip as possible. Longer pipes increase how raspy the sound is.
Don’t need a muffler on an 8:1. The Ultima had a 4”x6” silencer/resonator. Supercharged will be louder, so maybe go with a 12” one
Need to be careful not to blow a supercharged engine up with a 8:1.
Buys merge collector and parts from www.spdexhaust.com 888-778-3312
Spedex (Chris very helpful)
2” OD, 60 thousands in between
25-degree bend to keep short.
Length depends on bend and size of outlet. Bigger outlet results in shorter length (i.e., less room to taper). Assume 8-10”
Could go with two outlets… sound primarily driven by 8:1
Burns Stainless (Vince)
Oval horizontal mandrel to 4”
Oval pie cuts up to 5”; horizontal and vertical
CXRACING; 8” diameter; 6.5” tall