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Under Car Exhaust
Johnmor - 10/8/20 at 08:57 AM

Hi all

Managed to raise my engine and place the exhaust under the car
45mm stainless with cross over pipe and boxes from Suzuki GSX 1300 (standard) im hoping the noise levels will be ok

I have around 100mm clearance, fingers crossed

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CosKev3 - 10/8/20 at 10:48 AM

Have you thought about the heat going into the cockpit?
I know of people that say its unbearable with underslung exhausts.

Ground clearance will be massively reduced with two people in the car.

Have you got the car at the correct height for the handling to be correct, if you've raised the coilovers to gain ground clearance without considering the effects on handling you could well make the car drive like a pig just to have underslung exhausts that will cook you alive once you get stuck in traffic!


Johnmor - 10/8/20 at 11:44 AM

Hi

I built a viento with under body exhausts previously with an Afa V6, no real issues with heat
ground clearence maybe an issue but the exhaust is the same level as the sump, so if the sump hits its a problem regardless of the exhaust

I have side pipes and may alter after IVA , but to be honest the IVA test with stainless side pipes can be a pain, and its getting tougher, as long as its secure little attention is paid to underside exhaust during the test except the standard noise test.

Previous Alfa passed noise with similar suzuki cans , in addition i can slip on race cans after IVA , easy job and £60 pair on fleabay


Slimy38 - 10/8/20 at 03:13 PM

That's very nicely done, even the angle up to get the boxes up a bit. I'm trying to think of a solution to avoid the side pipe as well, this is probably the tidiest one I've seen.


Johnmor - 10/8/20 at 08:06 PM

I used motorcycle exhaust cans before and they make things fairly simple, they are a good size and shape and often sit at the right angle to allow the exhaust outlet to sit plumb at the rear of the car . The noise suppression is pretty good and they are cheap second hand

The clearance should be ok, I haven't raised the suspension and the lowest part of the exhaust is around 100mm from ground level, thats with the chassis rails 165 at the rear and 155 at the front, I think that is fairly standard.

Heat maybe an issue so I will use some 1mm aluminium to form a simple heat shield between the floor and the exhaust tubing.

I'll see how things go

John


nick205 - 11/8/20 at 10:43 AM

Looks neatly done and nice to see a 7 type without exhaust(s) running down the side(s) of the car.

Looking at the sump has it been modified to raise the lowest part of it? Many builders modify their sumps in that way to increase ground clearance. 100mm should be OK, just take care over speed bumps and the like. From memory I think my MK Indy had about 120-130mm ground clearance at the lowest point (sump), but I had modified the sump to raise the lowest part of it.


Johnmor - 11/8/20 at 03:22 PM

Thanks,

I did look at modifying the sump but too many horror stories with rover v8 sump modifications so I decided to raise the engine 25mm and change the carbs for something lower,
Yet to see if this all pans out but I'm hopeful

The last viento i did had an alfa v6 , its was a squeeze under the bonnet and i had around 90 mm at the sump, as you say just had to watch speed bumps,
People forget the engine sits well behind the fron wheels and often as you descend the speed bump the sump is barely still over it.

Not too concerned over the exhaust but did look at 55mmx30mm oval pipes but its was getting little expensive

The exhaust cans are around 120mm clear so should be fine

John


Irony - 11/8/20 at 03:29 PM

Might be worth considering a cross over pipe or H pipe to join the two exhausts together. I have heard that this is a epic way to enhance the V8 burble. Virtually impossible on my side pipes but easily doable on your pipes.

Lets face it, no-one puts a RV8 in for the power, it's all about the noise and torque.


Johnmor - 11/8/20 at 05:01 PM

Hi,
Crossover pipe is there,

Stops it sounding like 2 four pots


steve m - 11/8/20 at 06:00 PM

My gearbox bottom was just over 100 mm from the ground, and I gouged a few speed humps around my area
The best ones in Crawley, Susse where my Son lives, still have the gouge marks now, and it always makes me smile

a nice big groove of about 1 cm straight down the middle, of every one, both ways !!

steve


coyoteboy - 11/8/20 at 06:02 PM

Neither sound like 2x 4pots!
https://www.youtube.com/watch?v=b6-zwK5th-4


steve m - 11/8/20 at 06:06 PM

Attached an article, that some speed humps are 6"/150mm high

http://www.speedbumps.co.uk/


Johnmor - 11/8/20 at 07:57 PM

The exhaust has a similar cross over pipe to this so with any luck it should sound similar

https://youtu.be/Wt2DcRW6r-M