Yes, even that little will make a huge difference. The difference in cross sectional area of a 1 5/8 pipe vs a 1 7/8 pipe is ~2.07 vs ~2.76 square inches.That means a pipe with only a 1/4" larger diameter than a 1 5/8"pipe has a33% larger cross sectional area. You have to think geometrically, not linearly. The larger the pipe already is the bigger the effect of increasing the diamter by even the same amount. It's very easy to get too big a diameter too quickly with pipes. You double the diameter, you quadruple the area. Also since the strength of the negative pressure wave generated by power pulsing(a vital part of exhaust system tuning) is dependant upon the difference of the cross sectional areas of the primary vs collector, changing the primary diameter to a larger one will shift the rpm range that the power pulsing is most effective in to a higher rpm(all things being equal).

Basically, if you plan on doing more mods in the future and putting some good power out of that engine, then the larger pipes would be a better bet. You may suffer some power loss now at low rpm, but later on when you do generate the exhaust flow from more power you'll have big enough headers. Otherwise you could buy one set of headers now, and another later on. If you don't plan on doing anything other than mild mods, then you'll be better off with the smaller diameter headers

 

ok. well this is my only option availibly for what i have set up. so its better than the stock manifolds right? what the heck ill just go ahead and order them. thanks for the info.

one last question, that alot might be able to answer.
- do the shorties sound just about as good as the longer? do they have that hollow tone? how about agressiveness when reving?

thanks guys!!!

 

That's gonna also depend on the engine, the rest of the exhaust system including crossover pipes and mufflers

 

well its just a stock 351c right now with turbos and manifolds

vs it will be

a stock 351c with the shorty headers into a h pipe then into flowmaster 44 series mufflers and out the back with 3" chrome exhaust tips

think itll be a heck of a sound change?

 

Probably

 

alright. well what do you think the 1 7/8 is a good size for hp and torque wise? is it good for350-400? 400+??

 

Are you saying 2v hedmans won't fit your application? Did you get the right part number?

 

The Hedman heders won't clear his tranny and floor evidently.
I'd dump the power steering and cut the headers as required.

Everyone that is building a 2V Cleveland for the street should not be forced to use 4V headers...

 

I have 2v heads and an FMX tranny and my 2v hedmans would have cleared the floor easy if I didn't have a taller windsor block. The tranny is not a problem nor was the power steering. I think he has the wrong headers...

 

really? well summit says for c4 only so maybe they just havent tryed it on the fmx. i wonder if it will hit the bell housing? what do you think?