Front Fender Exhaust Downpipe Layout HELP

Im in the process of the build where I'm mocking the downpipes up and trying to figure out where I'm going to be able to exit the piping. I have the turbos mounted inside the fenders and I have started to run the pipe up and over the front tire and have a straight shot out the side of the fender with a 90° bend but its going to land on a fender fin which well be a pita cutting in the fender with a 5 1/4 holesaw.
I may be able to put a 45° bend in which will kick the pipe down some and get it lower then the flare in the fender.
Where I need help is some ideas on laying out the thru holes so both sides are coming out in the same spot. I cant afford to make a mistake so I need some insight before i decided to pull the trigger.

Is there any room to have it turn 90* immediately and dump it in front of the front tire on both sides, behind the headlights?

Out the top get my vote.

Seems like 5 inch is huge for twins, I'd neck it down if the turbine wheel is not 5 inch

Get yourself a couple of 2x8 chunks of wood. Hole saw one of them first, put the other on the back side, C clamp them in a fashion that doesn't bend the fender all up. The side that is already sawed will act as a real nice guide. I do this when I need to make oval holes and it works really well. I will also serve as an easy way to make sure the hole ends up where you want it. You can use this method at an angle also if you need to.
And yeah.... out the top would be my choice also!

Turbos are where the headlight buckets use to be and theres not enuff room between the tires and the turbos

I could neck it down but I'm trying to keep back pressure to a minimal

This is a great idea TRENDZ thanks. Out the top of the fender isnt out of the question but the natural curves of the fender made it pretty easy to get it over the front wheel.

It might be the angle but it looks like the tire will hit it on compression

For what it's worth, mine neck's down to less then 4" as it passes the torsion bar. So far with that tied to another 8 feet of exhaust and muffler it's supported 850+hp on single exhaust.

So as long as you're not trying to make more then 1700hp (850hp x 2) you've got plenty of room in the backpressure department to downsize.

I suggest getting the hole in the fender where it belongs, and finding a way to connect the dots, even if that means reduced diameter or pie cutting something to get the bend tighter.

Don't give up!!!

Probably the angle theres 26.5 inch tires on the car right now and when the suspension is compressed theres about a 1 inch clearance I dont have my front runners on it yet which are about 24 inches which should give me another inch of clearance.

[quote=dizuster]For what it's worth, mine neck's down to less then 4" as it passes the torsion bar. So far with that tied to another 8 feet of exhaust and muffler it's supported 850+hp on single exhaust.

So as long as you're not trying to make more then 1700hp (850hp x 2) you've got plenty of room in the backpressure department to downsize.

I suggest getting the hole in the fender where it belongs, and finding a way to connect the dots, even if that means reduced diameter or pie cutting something to get the bend tighter.

Don't give up.

No worries about giving up Im closer now then ever before and im getting excited my car is final starting to look like a turbo car once again. I'm just nervous about popping a couple big azz holes in the sides of my fenders

Heres a pic of what Im working with this is the passenger side. Both side are pretty close to Identical

As long as the exhaust pipe is the same size as the turbine wheel your good.

I think the holes look better farther back and lower on the fender.
But mine exits the hood lol

Do you get any flame out of the pipe on a hard run?

Ive seen some cars throw flames when they come off the 2 step....or when guys play games staging there rides at the line

Or when you cook the top of a piston

Out the top, plus it will help keep the nose down lol.

I don't get any flame yet. But I leave at low boost. My best 60 foot has been at 7 psi. 1.15 sixty

Why does it need to come out the fender? You are already running it over tire, just come down the back of wheelwell and let it dump straight down or turn it out a little right at bottom of fender.

Like this. Also this car has twin Pro Mod 88s and runs 4 teens. You don't need 5" exhaust

No front clip pic to see size and how it's run

This is a good point that I haven't thought about. And would be the easiest most direct route to exit the exhuast, I was pillaging around a area at work that stuff gets piled up and never used and I found a couple 5 inch rain caps that have been long forgotten that I saved just in case i decided to take it thru the top of the fenders and they would be easily removable for track outings.

Guys I can easily neck the pipe down to 4 inch if theres a need to. But in my opinion and correct me if im wrong a big block Chrysler proforms at its best with a good flowing exhaust ie big header tubes and the least restrictions as possible. Now a turbo car doesnt need the big primary tubes and the larger tubes and actually hurt your turbo spool characteristics. So IMO if I can fit the 5 inch pipe where it needs to go why not take advantage of the possible gains that running a free flowing setup might give me, and to my limited knowledge theres no downside to running to big of a downpipe.
Future plans are to run a aftermarket block with a 4.5 inch bore.....

Thanks and keep your opinions and ideas coming
Aaron

I know on my old Cummins going from 3"to 4" lowered egt's noticeably. I know there is a point where there is diminishing returns because heat can help spool up.

5" won't hurt anything. If you have space for it, go ahead and use it. If it gives you fits, go smaller.
The exhaust turbine works at its best when there is a wide inlet to outlet pressure ratio. I think you are distant from being at the point where 4 to 5 makes any difference.

Another example of More's Law:

If some is good,
More's better, and
Too much is just right

R.

For anyone that cares I got some info about sizeing of downpipes guy on YB says that 120% of the exh. wheel exducer is the rule of thumb for DP sizing

So If you have the 87/96 wheel on the S475's thats 3.4". So 3.5" off each turbo is fine.

If you have the smaller 74/83 wheel S475's then thats 2.9"... so 3" is fine.

That's assuming no sharp bends and a reasonable length of pipe. For most of the short dump style turbo exhausts 120% is plenty, no need for larger.

Keep up the good work

Thanks Fastmop mockup should be done in the next week, Im hoping to have it tore back down before the first snow fall. Plans are to clean the engine bay up,strengthen and lighten the K member,and finish the cage up,and get the car ready for some paint.
Ive also been tossing the idea of ditching the torsion bars and doing a coil over conversion while everything is a part but I haven't made my mind up yet, I had planned on running the car in some stock suspension classes and not sure how a coil over conversion will affect that decision.
Ill try and post a pic of final mock up in the next couple days.

Most "stock suspension" rules allow for coil over conversion as long as double A arms are kept, yeah? Chevy and Mustang guys can run bolt on front clips and aftermarket k-members and suspension...