Full exhaust on a 800hp street car

[My427stang]

I think I'd mix flat and oval to wherever it was an advantage, to include standing it on it's side along the gas tank.

A lot of fab time, but could be slick

[Dan859]

Following up on My427stang's comment, couldn't you swage the ends of the pipe to make them round and fit onto each other, then rotate the pipe into whatever orientation that you wanted?  That might make fitting it into different parts of the car a bit easier.  I especially like the idea of running the flat side along the floor of the car, then rotating it 90* to go over the axle and along the frame and gas tank.

[66FAIRLANE]

I'd just like to add...….Good Problem to Have!!

[plovett]

Do any of you really think twin 3.5" exhaust will not cost some horsepower on an 800 hp engine?

paulie

[427LX]

Well what is Ford using on the 700+ HP 2020 Mustang?? 
Just use 3.5 to the muffler and 3.0 tailpipe. Even 2.5 tailpipe won't hurt a thing.

[mbrunson427]

This made me curious, so I looked up an online calculator.....

http://www.mk5cortinaestate.co.uk/calculator5.php

Claims 3.00" pipe is good for 739bhp. 3.50" is good for 1006bhp.

[plovett]

Well, there is a difference between maximum supportable horsepower, and whether a pipe size costs power.   Is it conceivable that two 3" pipes COULD support 739 hp and whether two 3" pipes would not cost any hp?

JMO,

paulie

[My427stang]

Do any of you really think twin 3.5" exhaust will not cost some horsepower on an 800 hp engine?

paulie

What's the alternative? I think it's all in execution, if done nice it'll work well, cobbled together, not as much

[plovett]

Well, that was not my question.  But your question is certainly valid.  And your question is more to the point of the OP's question.

800 hp is A LOT!  I guess I figure that when you are at that point everything is out the window and you can do what you want, even if your exhaust system costs you 50-100hp it is still going to be a crazy ride.

JMO,

paulie

[RustyCrankshaft]

I found these sources online.

http://mandrelbendingsolutions.com/oval-tubing/

https://www.racemufflers.com/Oval-Exhaust-Tubing-s/1832.htm

Interesting, thanks for the links.

But I'd have to say, I don't see any way to get curves while going over the rear axle, using those bends.  Not to mention the 'flat' part of the oval is on the 'side' of the tubing (as it would be used to go over an axle), which means it's taking up valuable space. Space that just isn't there on many cars. I just don't see how oval tubing could be used in a full system, unless it was dumped out the side, and I'm really not a fan of that. One problem going down a track, or even a highway, and you'll be spraying your tires with oil. My instinct tells me that that would not be a good thing.

You can, it just takes a LOT of effort. You can get several styles of "twist" so that you can transition from vertical to horizontal, or the other way around. You can also make pie cuts, or buy them and make whatever angle you need. It's certainly a lot more work than dealing with common full round tube, but it can be done if you really want to.

Use a twist to lay the oval on the side, go over the axle, and another twist back to vertical if you so desire or require.

Here are some pre-made pie cuts in oval tubing.

https://www.racemufflers.com/Oval-Exhaust-Pie-Cut-s/2181.htm

[TomP]

The new 760hp Shelby GT500 seems to be 3" but at the X pipe it necks down, looks to be 2 1/2" at the smallest point. I bet there will soon be aftermarket X pipes claiming an extra 40hp. They used 2 3/4" pipe on the last 662hp 5.8L GT500's.

A local ProStreet car had oval exhaust before that was available aftermarket. It was made by slitting the 3" round pipes in half and adding 2" strips. It was 3 x 5" oval, probably similar to 4 1/4" round. The pipes had the flats at the top and bottom to fit under the floor and then turned upright to fit past the gas tank and springs. Round tips. I wouldn't have known until I saw the exhaust for sale at a swap meet.

[jayb]

My experiences with high horsepower street engines have led me to use a smaller exhaust pipe over the years, coupled with some electric cutouts.  Actually being able to use something like 800 HP on the street is not possible, in my experience.  You'll just spin the tires.  I've done burnouts while going 65 or 70 MPH; what's the point if you can't hook the tires? 

If you do decide to go with a big exhaust, think about how much weight you will be adding to the car, compared to a smaller exhaust.  On the street, the big exhaust won't help you, and the extra weight will slow you down.

Put a good 2-1/2" exhaust system on the car, with either electric cutouts or caps that can be removed at the track.  With the electric cutouts you can open them on the street if you want to get full flow through the headers, and if you go cheap with the caps, you can pull them off easily at the track to get your open headers that way.  My advice is not to waste a bunch of time and money on some huge exhaust system, because it won't do you any good.  Just my opinion, of course...

[plovett]

I mentioned that, too.  That is, once you have reached the ideal pipe size, going bigger just adds weight.   And of course it makes packaging more difficult. 

I would still tend to err on the larger side.   The weight gain from 3 to 3-1/2" can't be too much?  And choking an engine even a little bit makes me feel bad.

What do you run on your high hp engines, Jay? Small pipes, but with cutouts?

paulie

[jayb]

2-1/2" pipes with decent mufflers, and electric cutouts.  My Mach 1 (supercharged, about 900 HP),  used a 3" pipe system (pictured below) and I always regretted doing that.  I put the electric cutouts right in line with the collector extensions, and took the exhaust off the side of the extension.  That exhaust system was a pain to build and get it to fit; if I ever redo it, I'll go back to 2-1/2".  My Drag Week car uses 2-1/2" pipes, and I just drop the whole exhaust system when running at the track.

[Stangman]

Hey Jay do you think your cool with that exhaust . That looks to good to start the motor.!!. How do you drop the exhaust when you go to the track. I have the over the rearend pipes then no tailpipes which is easy to drop the exhaust how do you do it with the tailpipes on it. They dont look like they come off.