14 replies to this topic

[Bob Riebe]

From ENGINE LABS:

https://www.enginela...-racing-appeal/

 

They do not give HP but I am guesing around 600-640.

 

Edited by Bob Riebe, 01 February 2023 - 23:18.

[MatsNorway]

I never understood why Individual intakes was not more common in american V8s.

[mariner]

I think because with low hood heights you have to squash the intake manifilold flat in a production car and , being Detroit, one four barrel casting is cheaper to machine than  buying four separate carbs 

 

Going a bit nostalgia forum, when Lotus bought Ford 289's for the Lotus 30 sports racer they tried to use TJ injection , partially it is said because the four Webers on a race 289 cost way more than the engine.

 

Also if you watch the video you will see   a spray of raw fuel jump out of the cut down intake trumpets at each blip, not what you want under the closed in hood of a  production car.

 

BTW if you love the small block Chevy V-8 the good news is that GM, despite its total EV commitment is investing nearly $1B in new SB mfg. facilities

 

 

 

 

https://www.enginela...d-sixth-gen-v8/

Edited by mariner, 02 February 2023 - 11:02.

[Bob Riebe]

There were some side-draught carbs., 70 plus years ago but by the sixties I think they were long gone.

 

There were in the forties and fifties, some manifolds for six to eight Stromberg 97s or similar such carbs.; at least twenty, heck, probably thirty years ago a well known high performance car rag did test multiple companies carb. manifolds including a, even then , very old multi-two barrel carb one.

 

They were surprised that ,that one, while it had a narrow RPM range did produce a goodly more HP than they expected.

[10kDA]

Many road racers were running Weber DCOEs on crossram manifolds into the mid-60s because those sidedraft carbs worked well with the typical smallblock GM and Ford V8s. Weber downdrafts were not as popular though one would think since Maserati had been using them on their big-bore V8s, there must have been a few models that would have worked with American V8s as well.

 

GM's progressive Tri-Power setup made plenty of power. In 1967 and 68 that 3 2bbl. configuration was making 435 hp , the highest rating available from the factory, in the Corvette. And the big old Buick Nailhead made a lot of torque with 6 or 8 2bbls - Pretty sure that's what Max Balchowski ran in the early Ol' Yallers which commonly beat cars with far more exotic pedigrees back in the 50s - 60s SoCal roadracing days.

[Wuzak]

Curious as to which vintage road racing categories allow engines as big as 500ci +?

 

Can Am?

 

Anything else?

[Bob Riebe]

Curious as to which vintage road racing categories allow engines as big as 500ci +?

 

Can Am?

 

Anything else?

The old IMSA AAGT, SCCA Class II cars , last time I checked, were not inch cubed controlled.

Can-Am is open.

[Lee Nicolle]

I never understood why Individual intakes was not more common in american V8s.

Why? because a decent 4bbl on a decent intake makes more power. It kind of defies logic but that big plenum under a 4bbl helps make power and torque. And they generally fit under the bonnet better as well. IF you spend a very large amount of money on efi you may beat the 4bbl power but on Webers give me a Holley.

DCOEs with the right intake [none available] may be better but harder to work around.

I have used DCOEs on 6 cylinders and they are good BUT are allergic to rough roads. And get surge. I have seen people do all sorts of stunts to fix it and none have been succesfull. So 4 x 48mm Webers will cause some fuelling issues

[gruntguru]

I wonder if it has something to do with headers? Individual cylinders have differing wave tuning requirements due to the 4-1 header seeing very unequal arrivals. Engines with better exhaust layout (eg flat plane V8) can better utilise IR intakes.

[ray b]

4x2 is the only factory one to one and most only on full are all open on a v8

kind of rare more race then street used

max wedge had 2x4 but way out on long ram tubes

 

the 6-pack 3 two barrels was super common on hi-po motors but progressive links

 

I think by 70 most were one big 4 barrel for the max power

even if hidden like chevy with race motor derated 500+++ to listed 425

 

some custom motors use bike FI bits to get 1 for 1 like on north stars or LS hot rods

nite-mere if a turbo for tubes

[Greg Locock]

" a spray of raw fuel jump out of the cut down intake trumpets at each blip, not what you want under the closed in hood of a  production car."

 

My TR4 had exactly that! I think a previous owner had fitted Webers, don't know why.

[Bob Riebe]

For what it is worth:

 Chrysler, Cad, Packard, Ford,Mercury, Plymouth, Dodge, DeSoto,Chevrolet, Pontiac  all had two four barrel carbs at some point in the fifties.

Ford, was probably the last to offer them on its 427.

Edited by Bob Riebe, 25 May 2023 - 15:46.

[Magoo]

On a V8 for everyday civilian use, an intake manifold with a common plenum provides a smoother, more consistent idle and better low-speed driveability.

 

Eight isolated, individual throttle blades must be rather closely balanced at idle. Aka "carb synchronization." 

 

On American production cars with more than two carbs, the factories usually dodged this issue by eliminating the idle circuits in all but one carburetor. 

[Magoo]

Okay, look  at this: A 5x2 carb setup for the American V8. It looks a little crazy but it actually works slick. 

 

First, it could be constructed by modifying  a production two-barrel intake manifold (or the patterns for it, working at the factory level).

 

At idle and low speeds, the engine runs on the center carb only, just like a stocker. When the throttle pedal is mashed, the other four carbs go to work. 

 

The linkage can be mechanical or vacuum-operated (like the secondary circuit on a progressive 2V or 4V carb). 

 

You can see the mixture distribution is pretty nice  at WOT, also. Not totally sure why it didn't catch on.  Maybe just looked strange. 

 

For more info here's an entire story. https://macsmotorcit...retors-why-not/

 

 

 

 

 

 

 

 

[Lee Nicolle]

If you want some interesting intakes look at the Perkins Engineering You Tube Channell. One of their 40 plus episodes [ep 27] has a piece on Larrys slide injection for a V8 Supercar for the Holden V8. Like most of Larrys good ideas it was banned after a period

It does help ofcourse to have Holden lift the intake ports about 20mm in the cylinder heads.