Hello, I would like a recommendation on header & exhaust size(and source) for a 70 with a 454. On the engine dyno it made 450HP @4800rpm and 525ftlbs @ 3000rpm. I have a feeling my current Hedman ceramic coated 2 inch primaries into 3 inch collector are too big (blowing through a 2.5 in flowmaster exhaust system). Silly me, I already had the exhaust system and didn't ask the engine builder what header size was on the engine during the dyno pull a ways back. What sort of gains could I see? May not be worth $$ to swap?
thanks -Erik

anyone? would 1 3/4 to 3 inch be better or significant gains?

ErikNORcal,

I think that the 2" are probably fine. thats a fairly healthy motor & 2" are not big time overkill. I dont think that you are going to find that the gains are going to be worth the bucks to change it out. leave it on there hook the bottle on & get those ET Streets out for some abuse;)

Bob

i think your 2 1/2" exhaust is fine if you really are searching for more torque by all means go for the smaller 1 3/4" headers even the cheapos from summit for 80 bucks work darn good thats what im running in my 10 sec car.......and im spinning it just past 7000 rpms.......i might gain something going bigger on the top end.......but for the rpms you are turning im sure you will see a difference in the low range with smaller tubes.........

i know yours is the 454 but when iwas playing with my 396 i lost torque big time with 2 inch tubes in the 1/4 mile even at the 7000 rpm limit i had on it.....i lost 8 miles per hour with my combo.i went back to the summit headers.

i know thats not apples to apples but there might be something there to look at.

DDeenis and Bob, thanks for the input. I figured the 2 inch would cost me torque. I'm glad you gave me some stats, that really helps!. Guess I'll see how close I am to some 11's and switch them over if I need to get down a few tenth's!!!

Bob, good to see you on this board too! What a wealth of info. I'll be in SD this weekend to turnover the motor and help a friend move. I'll have to change the name from ErikSOCAL to ErikNORCAL and apparently to ErikHAWAIIAN in a few month's for another move! Good news is they have a really nice dragstrip on Oahu and looks like the 'velle will make a transpacific journey since its cheaper to ship a car than pay for storage. Probably sell it over there when it comes time to move again. Hope your mean project is coming along! BTW, I went 12.1 at 117 at Cbad in July heat with the Z06 on ET streets. No mods, no skill, no experience - scary for a factory car.

Hey Erik,

those Z06's are BAD!!! there is simply no getting around it.

I cut my first teeth there @ Campbel industrial park, there on Oahu (my "home island"). if they are paying to ship it over, have them pay to ship it back. that kind of sucks that you have to move again so soon. I wish I had the room to help you out.

My car is coming along. Im fixin to put it onto the ground & either today or Monday I should be getting my Pro-System Carb for it. I CANT WAIT, to start playing. The new Track @ Barona hooks like Bubble Gum & the folks there are first rate. All I need now are a good set of heads & a new cam & I am Golden:)

talk @ you later amigo
Bob