I am looking for how much clearance a Sinister 4 inch exhaust has. I have custom y pipe being made to fit the headers (OBX/DNA) but want to give the guys at the exhaust shop something to go off of for both y pipe and possibly the 700R4 crossmember. I know there is no longer a "double hump" 700R4 crossmember that comes off the shelf anymore unfortunately but if anybody here has one, shower me with pictures and experiences.

 

If you have shorty headers, easy. It doesn't effect the crossmember

If you have long tubes, then you need to get crafty.

Search my name in the thread about Ed Quay headers.

4" pipe after the merge has great clearance.
I got another panhard hard, to make for more room.

 

subscribing to this. I hope someone has what you are looking for and can post up some specs and photos.

Also, would you be willing to post some pics of your headers and overall exhaust setup/plan ? Next winter I will be doing a 4" setup to help my 406 breath better, especially when spraying the nitrous. I also have a 700R. I'm aware I'll need a custom y-pipe built.

 

I’ll be doing this same setup with Hooker 2210s to the 4 inch single exhaust. I’m installing the Hooker Blackheart crossmember with an adjustable transmission mount to support my 700r4 and will get some pictures. I’m hoping to get it installed within the next week.

 

definitely will do!

 

That would be great! I know the blackheart crossmember can be used but we have to modify it. Truth be told, if im buying a crossmember for 350 bucks i don't want to mod it or pay a welder to mod it. Not sure if i trust myself doing cutting and welding....yet

 

its longtubes

 

https://www.thirdgen.org/forums/orga...y-headers.html
Post 50 is where I posted pics

https://www.thirdgen.org/forums/susp...rame-next.html

https://www.thirdgen.org/forums/exha...ns-member.html

With those mods to the frame, oval exhaust & trans crossmember, the long tubes fit in there no problem.

 

There aren’t any mods required that I know of. You just need the adapter plate from Hooker for the 4L60E and an adjustable mount.

 

Custom Y, you can snake around the trans subframe and cross member. 3” and then come back under the torque arm from driver side to merge into a dual 3” to 4” collector. Then mate the sinister from there. It may need modified however

the dual 3-4 collector will have to sit back behind where the factory cat used to be

 

Spotted this over on ls1tech. Can see the adapter to 3 inch
may be someone can score a descent deal on it.

https://ls1tech.com/forums/market/1945190

 

I did a test fit of the crossmember yesterday, and the room on the driver side is massive. The pan is still going to be an issue on the passenger side, but it is at least improved. I am going to have to flip my adjustable transmission mount around since the front of it hit the back of the pan, but it worked perfectly.

 

I finished mounting the crossmember today, and flipping the bottom half of the mount worked like a charm.

This is the mount I used: https://www.summitracing.com/parts/sum-773200

 

that mount looks like a great idea

 

Figured I’d post an update as I finally had the exhaust installed a couple weeks ago. It has significantly more clearance than the turn downs I previously had on it. It’s more than a beer can diameter so I’d say about 3.5” or so. The muffler shop did a great job tucking up the pipe coming out of the rear too which can be seen in the idle video.

 

that still sits pretty low though.
It will work, but just be careful!

your panhard bar has quite an upward angle to it. do you have any way to make it less drastic? let us know how it performs. I did my exhaust system overhaul this past winter and I am glad it is done with! I did a whole thread about it : https://www.thirdgen.org/forums/exha...s-700-a-3.html

 

Yeah, I’m expecting it to drag every now and then. I have the Eibach Pro-kit springs with the isolators removed all the way around and replaced with heater hose which doesn’t help.

Between that and the panhard bar relocation kit I put in to be able to keep the heat shields in place with the 4” pipe, it puts the panhard bar at that angle. I’m debating buying a lowering kit for the axle side as well.

Now that the exhaust is installed, I’m switching to an MSD Atomic 2 setup to replace the carb and have mounted the fuel pump to the aluminum plate you can see mounted to the rear seat well. I’m about halfway done with it as I get a few hours here and there to piddle between work and the kids.

I followed that thread very closely, and well done on the install. Yours came out really nice.

 

ah yes, I see your suspension stuff puts you low indeed. Not to worry, just be careful .
Glad you got the exhaust project done and are moving onward to fuel stuff. nice

 

with the PHB relocation on the frame side you have to lower the axle side to be parallel at ride height otherwise your geometry is all off. But once you do this your rear roll center is not right and you will have to increase the rear spring rates to compensate for added body roll. My 4” sinister cleared my stock PHB but I did have to lower it at the axle as I’m lowered a bit.

 

I already have the WS6 rear sway bar which I’m hoping will help some with that, but yes, I need to fix the height on the axle side.

Here’s a link to the sound. My comparison is only to open headers, but it sounds significantly better.

 

I am seriously concerning getting the blackheart crossmember and this looks like the closest example of what I am about to do. I've got a small block and 700r4 with a UMI crossmember and it hangs down way too far for the exhaust to clear. Before I drop the cash I wanted to know how it's working for you. The crossmember and adjustable mount. There isn't much info out there about doing things like this.

 

No issues at all. It provided great clearance for my exhaust, and it works with both the stock torque arm and the Founders one I just installed.

 

Thanks, it's good to know that someone has done this and it works well. Really frustrating that holley sells the full exhaust system, including headers for a small block that is expected to work with their crossmember, but not an adapter for 700R4 folks. Not happy to have to replace my torque arm and crossmember, but I guess it's better than having 2" of ground clearance.

 

It might be common mount with one of the other transmissions, maybe just not realizing it also fits a 700R4 ?

 

Which exhaust? I have my doubts that the Holley crossmember works with any off-the-shelf 3 inch Y pipe.

 

The TH400 mount works with the B-Body tailhousing as I believe @skinnyz found out, but nothing works with the F-Body tailhousing except the adjustable mount.

It’s custom-fabbed by a local exhaust shop. You are correct that an off-the-shelf option won’t work without modification.