HO exhaust question..

Topic: HO exhaust question.. (Read 1460 times) previous topic - next topic

HO exhaust question..

September 21, 2005, 01:01:05 PM

I'm still in the middle of my engine rebuild and things are coming along fairly smoothly if a little slow because I have other things going on. Now obviously I'd like to get more performance out of this engine so I've been planning modifications along the way that will bring it closer to the HO standard and perhaps substantially beyond in the future. But given my budget these are the changes I'm making right now:

-E7 heads off a 1990 Bronco w/351
-Mustang HO camshaft
-Set of underdrive pullies

The camshaft is certainly the most noteable change and the one that worrries me a little. In reading the tech articles at Coolcats I noted that a HO engine requires dual exhaust to function correctly. Now mine isn't actually going to be HO...yet. Still has the stock 2BL carb and manifolds for the time being. And the dual exhaust setup is in fact next on my list of things to do in say 2 months maybe. But in the meantime is mating that cam with the stock exhaust system going to give me any considerable trouble? Because if it will I'd just as soon leave the car layed up and get to the exhaust system when I can.

Re: HO exhaust question..

Reply #1 – September 21, 2005, 01:14:00 PM

Running the stock exhaust isn't going to be too detrimental to your combination but it is going to be a bottleneck that is worth getting rid of...you won't be able to take full advantage of those heads and the HO cam with a stock exhaust.

Re: HO exhaust question..

Reply #2 – September 21, 2005, 01:23:37 PM

Figured as much. But as long as the car will be driveable I can worry about the exhaust later. I'm looking forward to getting those aftermarket headers I've been dreaming about :D

Re: HO exhaust question..

Reply #3 – September 21, 2005, 01:43:50 PM

It will be driveable...I wouldn't expect blistering performance though. You could actually get some hesitation which has been reported to me by others running the factory exhaust manifolds. And it won't sound very bloody good either. But it will work for the time being. For the few bucks and wide availability of the factory Mustang headers, it's not really much of an argument to keep the stock manifolds though.

Re: HO exhaust question..

Reply #4 – September 21, 2005, 01:54:21 PM

Unfortunately one of the manifolds I have is fused to the pipe with decayed bolts. I don't really feel like messing with that until I'm prepared to cut out the whole system pipes and all.

Re: HO exhaust question..

Reply #5 – September 21, 2005, 02:20:46 PM

it wont *harm* the engine, but you will be lacking performance big time, the stock exhaust on these cars isnt enough for the factory engines

Re: HO exhaust question..

Reply #6 – September 21, 2005, 03:08:12 PM

It wont be any slower then it was before. And he is going to upgrade just not now.

Re: HO exhaust question..

Reply #7 – September 21, 2005, 03:16:26 PM

Are we talking...less performance than it had before?

Re: HO exhaust question..

Reply #8 – September 21, 2005, 03:20:28 PM

You'll probably be short 20-25 hp since your car is an 83'. But it's definetly not going to kill you to run the factory single. I ran a factory single on my 86 blue max for almost a year when I converted it to H.O with a .060 over 5.0L (It was the exhaust off of my '85 5.0L cougar) before getting duals. The older 5.0L cars have a better single exhaust than the EFI ones. It was a noticable change, but the car definelty had more low-end with the factory single. Afterall, a 2001 and newer 4.6 can make 239 hp through a 20' long 2.25" single exhaust and 260 through the mustang's dual setup. So on our 225 hp 5.0L, you're not going to be doing any harm for the time being, especially if your car is an '85 or older

Re: HO exhaust question..

Reply #9 – September 21, 2005, 03:37:53 PM

Didn't see your post Haystack. That's all I really want to know for now. I'd hate to do all this work and then limp around for a few months. And for Mercoug302, yeah I've got some considerable planning to do on that new exhaust system. I don't want to lose low-end, low-end is my bread and butter. I love it when I stomp on the gas and the car bucks and rips up some ground :D I know that smaller diamter pipes are better for that sort of application. I'll work it out I guess.