[Warrant]

I'm trying to mount pre-bent 3 inch tailpipes on a 72 with a 275/60 tire, they are technically for a camaro, flowmaster kit 15822. (It was the only 3" tailpipe I could find that would likely fit the nova, and I don't want tailpipes exiting out under the bumper, and I don't want 2 1/2, so its got to be this kit) Anyways, the bending isn't quite perfect, it gets awfully close to the tire.

The best I can get is about a finger width between the tire and the pipe. How hot do tailpipes get? Hot enough to melt the tire? Im sure there is lots of variables, but its a full 3" system with flowmaster 10's if someone has a similar setup.

 

[Ericnova]

It's not going to melt the tire except for maybe if you do miles of sustained WOT running, like the Silver State Classic or something like that.

At that little clearance, the tire is going to rub that pipe during cornering. Leaf spring and bushing flex, and the tire sidewall lean from cornering would make it rub with double that clearance.
I've got the same 275 M/T's on my '72. on 8.5" wheel with 4-7/8" backspace. Tire sidewall rubs the shock casing during corners but clears the 2.5" tailpipes. About 1" clearance between sidewall and the shock upper half's shield around the inner rod. Doesn't hurt the tire, just leaves a black mark on the shock's paint and a scuff on the tire sidewall.

 

[wolfmantough]

It might shiver your timbers, but I don't think it'll melt anything.

 

[bracketchev70]

That tire will rub hard.

and to the other poster, we used to cut the upper shock can off leaving just the rod.

 

[JIMS63s]

Take a c-clamp and oval the pipe in that area. Rather than denting one side, ovaling it won't cause a flow restriction but will give you clearance.

 

[Deeznuts]

Too close for me. I would fix that.

 

[Ericnova]

That tire will rub hard.

and to the other poster, we used to cut the upper shock can off leaving just the rod.

Already got that covered, the new Calvert Racing/Rancho RS9000XL adjustable shocks that are going on the during the same time as the Cal-Tracs are replacing the Competition Engineering slapper bars don't have the upper can around the rod.

I haven't decided if i need 3" exhaust or stick with 2.5"....I've got manual cut-outs off the headers so 3" full tails isn't a critical issue.

 

[bracketchev70]

Already got that covered, the new Calvert Racing/Rancho RS9000XL adjustable shocks that are going on the during the same time as the Cal-Tracs are replacing the Competition Engineering slapper bars don't have the upper can around the rod.

I haven't decided if i need 3" exhaust or stick with 2.5"....I've got manual cut-outs off the headers so 3" full tails isn't a critical issue.

I don't think 3" tailpipes are critical. The exhaust has cooled and lost volume at that point that the 2.5" tailpipes is minimal. Especially the short distance going over the housing and out behind the tire.

 

[nova 71-436]

I run 2-1/4" from the headers all the way back...well except the mufflers which are 2-1/2" ...the exhaust is not visible at the rear...but I wanted to make the car quite as possible with the best mufflers and whatnot like that...plus no clanking or rubbing on springs or tires...it's still obnoxiously loud ...the muffler guy told me using a larger pipe would make it louder

 

[nova 71-436]

and flowmasters are super loud...had a set still sounded almost like open headers...don't recommend them if you have a high HP motor

 

[Warrant]

Thanks for the advice, Ill look at cutting and re-clocking the tailpipes to get more clearance. I didnt want to until I was sure I could get it to work.

 

[jrs 427 vette]

3" is mainly for show. Very little advantage if your not running extreme horse power. I would go with 2 1/2 , the cutouts , and the last 2' of pipe 3" if you need the look.

 

[Warrant]

My main purpose for the tailpipes is to reduce interior noise and fumes, not look... additionally I could not find 2.5 tailpipes either that exit the way I want - behind the rear tire - I do not like ones the exit under the bumper. Looks awful. So you won’t be able to see the tailpipes anyways. The 15822 3” tails for a camaro were the closest that fit the bill. I see a lot of claims saying there is little advantage to a full 3” system including the tails but have never seen any back to back data. I can’t say if I’d see a gain or not, but I know for certain that won’t be choke point for my big inch mouse. I’d actually argue cutouts are for more for show, as I did not see any gain what so ever with cutouts on a previous car and it sounded like crap with them open honestly. 2.5 sure would have been easier to route though!

 

[nova 71-436]

I drove my car to a muffler guy and got rid of the flowmasters and replaced them with quiet mufflers that would fit in the slots in the floorpan and he bent all the tubing and made it exit without making noise rubbing or rattling (also not visible) and I asked what if the muffler blows out (not welded seams) he said he will fix it free of charge

 

[Dougs63]

Although this is Pontiac and they do not rev as high but it is a 455.
They show a very small drop in ET, MPH, and 60 ft going to 2.25 tailpipes.
I would think a small block with 2.5 tails would show less.
But we all what as much HP as possible but 2.50 pipe would certainly work.

2.25 tail pipes