Sbc Who`s running 1 7/8 headers

[swampy]

HI all
1/ are u running 1 7/8 headers what brand and collector size ??
2/ what is your engine set up , cu-inch ,head ,cam , inlet manifold


Info I found
It appears on paper anything over 400 cubic inches peak hp from 6300 and up . Hp requirement 500--550 minimum

What people donot realise is 1 3/4 headers depend alot on flange plate / port alignment mostly which is real bad . The way I fixed this is to potentially go to adapter plate headers .
Adapter plate headers are 7 bolt Stahl pattern . Beaware there is at least 20 different port shapes patterns that use the 7 bolt pattern.

[swampy]

hello

[RedTaxi]

Not me. 1 3/4" with a 2 1/2" collector. Hoping to crack 550hp with 355 cubes. Tk made 685hp with same tri-y sizes and cubes. They were holding it back apparently though. Plenty of guys have seen 550hp with 1 5/8" primaries.

[swampy]

Hi
Exhaust primary size calculators do vary . 1 5/8 std fittment to 350 chev . Approx 475--550 hp 1 3/4 is maxed out [sbc 383] . 1 7/8 tends to be Big block cubes 400+ etc or optional on LS series .
Ever wonder why sbc are almost rev limited besides cam design /size eg BB or LS . Big cube sbc is mainly held back by lack of cylinder head breathing .Inlet manifold designs are not to bad but the exhaust manifold to exh. port match is pretty ugly. The 2 options are 1/spread port head 2/ adapter plate headers ***Both use 7 bolt stahl exh bolt pattern .

The std 6 bolt squashes a 1 3/4 tube and there fore it overlaps some of the exh port causing disrupted air flow ==hp loss

On a street 383 /400 sbc 1 7/8 seem to give a little more hp but common thought is u would not sell a set of 1 3/4 to move up the gain is small. Really depends on how much of a drag car experience u want I guess .

[JaseQ314]

I was looking at a Pro Stock car Peter Ridgeway was associated with at Willowbank years ago and it had 1 7/8" headers, he even confirmed it when I asked him.

I haven't looked at a V8 Supercar up close for a while but they used to run 1 3/4" at over 600hp, spread port heads though.

[swampy]

Hi
I`m talkin spread port early chev ie gen 1 aftermarket 23deg not LS [v8 super car ] . Also matters what cubic inch and rpm your running .
For a 400 gen 1 sbc borderline for 1 7/8 according to online calculators . But hey not building a snail !!! Go fast in high rpm range is ok by me ie 4500-6500rpm.
Anything below that is cruising anyways and besides with 235 wide tyres traction is a problem .

Thanks Jase,, 1 7/8 headers sure flow for plenty of hp but need revs and /or cubic inches

[RedTaxi]

Hope you're not saying LS and V8 supercar in the same breath there.

[swampy]

HI
Red what are they running ?

Anyways thinkin of going 1 7/8 pri and 3 inch collector . This combo is rare but seems to appear on LS + variants and motors around the 400 cube ,409/348 ,,Dodge /Plymouth 383 -400--440 etc
The 1 7/8 3 inch is more than enough for N/A engines around the 400inch . Fitted to a 383 there seems to be a obvious loss of TQ between 3000-4000. A dip seems to occur on the dyno sheets 10-15 ft lbs . By comparison around 5 ft lb loss on a 427 .remember not trying to restrict rpm of engine max target 6500rpm .

By comparison 427 BBC seem to go well with 1 7/8 with larger 3.5 collector

[swampy]

http://www.superchevy.com/how-to/148-0404-best-headers-shootout
shows 383 a bit weak in the midrange with 1 7/8

https://www.youtube.com/watch?v=O1bXPNy1Yn4
427 strong with 1 7/8

calculator--- better than most
http://www.wallaceracing.com/header_length.php

[JaseQ314]

V8 Supercar aren't LS, from memory they call them Chev motorsport block and heads (Holdens anyway). I think the heads are a 15 degree spread port arrangement, both are certainly nothing that was available in a road going Commodore you could buy.

[swampy]

Hi
LS was naturally a spread port but the motorsport stuff who knows.
If Holden moved away from factory or variation of its engine thats just another reason why I lost interest .

[RedTaxi]

Holden motorsport engine built specifically for the Supercar Holdens. GM Aurora based engine. Basically a bespoke iron block 5.0L chev. Nothing LS there at all. Prob be the same engine when the Camaro debuts.

[JaseQ314]

Hi
LS was naturally a spread port but the motorsport stuff who knows.
If Holden moved away from factory or variation of its engine thats just another reason why I lost interest .

I started to lose interest when they forced the level one teams to use a Chev engine back in the day, an Australian racing class and they couldn't run the Australian engine for f#cks sake.

Holden motorsport engine built specifically for the Supercar Holdens. GM Aurora based engine. Basically a bespoke iron block 5.0L chev. Nothing LS there at all. Prob be the same engine when the Camaro debuts.

Yeah sorry, Holden motorsport, not Chev motorsport but definitely not Holden factory and definitely not LS.

[swampy]

Hi
there could have been a Holden Gen2 v8 --only if . But GM usa telling aussie what to do yet again ,look where that got the ozzy auto industry !!!
A high winding 5 ltr with 1 7/8 headers ,,why not the ford coyote does uses these .

[TRIKHQ]

Hi there,

I have a few engine builds on here, I am running 1 3/4 primary's on my 406 dynoed at 642HP. I have done a few engines now with the same size pipe. We have found if you go 650+ then 1 7/8 would be the next step up.