Horsepower gain with Webers

[hamster427]

How much hp and torque do you gain typically with a Weber setup vs. a single fourbarrel on a small block? Thank you for any responses,

Brian

[Excaliber]

For max h.p. at max rpm I would expect it would LOOSE h.p. over a single four.

Torque and throttle response will be better at lower rpms.

Just a hunch, not a Weber expert.

[CobraEd]

I agree. Webers are for low to midrange torque with massive off idle strength. At upper rpm, the intake reversion that normally "supercharges" the other cylinders in a 4 bbl manifold just backs up as a haze over the stacks in Webers.

.

[Full Throttle Al]

Buy this brand new small block set-up from Inglese and find out first hand:



Alan Sorkey
Shreveport, LA

[DMXF]

Depends on what single four setup you're comparing it to. From everything I've ever seen, a well setup weber small block will make perhaps 30, 40 or more peak HP than a period 60's 1x4 Holley induction equipped one. If you have a ported modern spider type single plane intake with a worked very large venturi Holley, they may be similar in peak HP. All the old Shelby American literature clearly documents the webers as being far superior, including more peak HP.....why do you think Shelby American ran webers on all of their team race cars? One notable advantage of the webers is they start off with much more uniform cylinder to cylinder mixture than a Holley induction. Formula 1 engines ran webers and then moved to IR fuel injection, the evolution of IR. If plenum type systems were superior in any way, wouldn't you think the F1 teams would have jumped on it a long, long time ago?

[Excaliber]

The GT-40's didn't run Webers at Le Mans. If I recall correctly Shelby even tried dual fours in search of more h.p. before settling on a single four.

For a road racing application the Webers would be superior not so much for max power as for "fuel slosh" control under high G level forces (braking, accelleration, cornering). As well as better throttle response at the low to mid rpm range, where the typical rpm's would be during a road race.

Le Man's was more about the ultimate top speed on the long straight, interesting that a single four was chosen in that application.

[DMXF]

Where do you get the idea the GT40's didn't run webers on the small block cars at Lemans? All the Ferraris ran webers at Lemans. Webers will be succeptible to fuel slosh issues too. If you read old Shelby American documents you will see how the webers made more peak as well as mid range HP.

[Excaliber]

I was referring to the 427 GT-40's. Perhaps engine size is a factor as well?

While what you are saying as it pertains to "back in the day" horse power, I remain skeptical that with modern cam shaft profiles, head design etc, Webers can outperform a single four for MAX horse power.

[Tom Kirkham]

In 1967 the MKIIb and the MKIV ran 427 with 2 x 4 carbs. John Wyer had a manifold built, and possibly homologated, to run 4 x 58mm side drafts.

[Excaliber]

Thanks for that update Tom. While I knew Shelby had tried dual fours (in search of more power) I've always been uncertain as to what he actually ran come race day. I've seen pictures of both the single and dual setup.

[zrayr]

Originally Posted by Excaliber

The GT-40's didn't run Webers at Le Mans. If I recall correctly Shelby even tried dual fours in search of more h.p. before settling on a single four .......................Le Man's was more about the ultimate top speed on the long straight, interesting that a single four was chosen in that application.

Shelby settled on a single 4 barrel in the example you site because they DIDN'T NEED more horsepower that the other induction systems provided. They were going for simplicity over complexity. That was the beauty of the 427.

Z. Ray

[Excaliber]

Arrggghhh, so did he run a single or duals on RACE day??? The answer seems to remain somewhat illusive...

Reliability is the KEY for a race like Le Mans, no doubt Shelby did not want to stress the engine anymore than what was needed to get the job done.

Now for reliability, you could make a stong case for the Webers! With few moving parts they are simplicity itself.

[zrayr]

from what remember reading, a single 4 barrel was used. I will get my reference books out and see what I can attribute to whom.

Z. Ray

[*13*]

I think, if I remember correctly, it can be in the 20% range. Seat of the pants is out of this world, on a SB ford. I switched from a 600 Holley Double Pumper to Webers. Even before I had them dialed in the HP gain was quite noticable. Highly recommended if you're thinking of making the Jump.

Originally Posted by hamster427

How much hp and torque do you gain typically with a Weber setup vs. a single fourbarrel on a small block? Thank you for any responses,

Brian

[ENTDOC]

I had the same experience when I switched from a Holley 750 to Weber IDAs on my 427so. It was really fun.

[DMXF]

Originally Posted by Excaliber

I was referring to the 427 GT-40's.

Yes, most all the GT40 big block cars did not run webers (I say most all, because the J car Ken Miles died in was specially fitted with webers), but that is really a separate animal from what Shelby American was doing. I can't devote the time to this post to expand on/substantiate all the conclusions I've drawn from alot of research, but a major factor does appear to essentially coincide with zrayr's statement about not needing more power and simplicity.

All evidence indicates Ken Miles/SA were always interested on running webers on all their race engines, but Ford's influence over SA's activities became overwhelming once they received the contract for the GT40 development and Ford's engineers were approaching things from a different angle: given the competition and their expected improvements, engineers back calculated required HP to achieve desired lap times and they were able to reach the targets with their slightly modified NASCAR type 1x4 engines during the initial MKII GT40 development. I spoke with Gus Scussel about this, who was one of the Ford guys in charge of the GT40 big block engine development and he said they didn't even really consider webers, as they were able to get the desired performance with parts they were already familiar with and he was interested in simplicity. They ran the 1x4 Holley on the MKII cars in '65 and '66.

Based on numerous inputs, other potential factors for them not going with webers on the big block engines include: Mr. Ford supposedly didn't want Italian parts used on his cars after the lost deal with Ferrari (especially something as prominent as the carburetors), he wanted the cars to most closely represent what an average consumer could purchase off the showroom floor in their Galaxie, they were experiencing durability problems with the big block and didn't need an induction that would only exacerbate the problem, the big webers were in short supply, and also the cost differential. The durability aspect was not insignificant - consider a dry sump system was developed out of necessity for the 427 engine after durability problems when using the Aviaid pan, yet they never felt the need for the same thing on the 289. Ford even set relatively low rpm limits during Lemans for the big block engines, I recall it was something like 6300 rpm for most of the race with short excursions allowed upon certain conditions.

As the competition became tougher and target lap times lowered, Ford pushed the development of the 427 engine and, probably also from NASCAR demands, the result was the tunnel port for '67 Lemans. Ford engineers found they were again able to achieve their targets with known components, by just going with 2x4 Holleys. Much like today's "customer engine" deals in F1, Indy cars and the like, Ford prohibited SA personnel from substantially disassembling or extensively modifying the GT40 engines as they arrived from Ford. Ex-SA employee Steele Therkleson remembers showing Ford engineers how SA detail internally prepped their engines so it could be done at Ford from then on. Ken Miles, however, was always trying to put Shelby American's influence into the cars and according to reports he pushed Ford to have the one engine in the prototype J car outfitted with webers for evaluation and possible fielding in races. When Ken died in that car so did all plans for use of the webers on the big block. Even if Ken would have been successful in getting the Ford engineers to seriously consider using webers, by that time fuel injection was all the rage and if the engineers pulled the trigger on IR there is a high probability they would have just gone FI. This was actually manifested with the FI on the 3 valve Calliope engine which Ford had developed by '68 for the GT40 as a potential successor to the FE (by the time that engine was finished, however, Ford had already pulled support of the Lemans effort).

[Tom Kirkham]

Here is an article about Fords Trans Am Mustangs...

http://www.mustangandfords.com/featu...302/index.html

Ford developed the Dominator carb with Holley to get around the rule of limiting the engine to only 2 carbs. This rule was made to eliminate Webers. Ford responded with Dominators and inline four carbs. Note that in the article it says the intake manifold is an IR (Individual Runner) manifold.

[Excaliber]

Just to reiterate were basically all on the same page here...

There is little or no doubt throttle response and torque at the lower mid range and reasonably high rpm range are improved with Webers and so it would seem with the inline autolite carb setup. All though the later could be debated. Take fuel slosh, for instance. Center pivot float is better than side pivot, Weber is better yet, degrees of improvement, just short of perfection (enter fuel injection). Hard to beat Webers for a road racing application or even street use (with the possible down side being poor mpg with Webers). All this ASSUMES of course the Webers in question are PERFECTLY tuned, not something to be taken lightly! Which is perhaps another reason Shelby wanted to stay with a single carb, it could be tuned to near perfection easier, more simply? Given enough TIME and TESTING the Webers may well have done a better job.

The sticky point for me here is, "absolute power". Take drag racing, Webers or Carb? You rarely see Webers in that arena, I wonder why? Serious question actually, not drawing any conclusions here one way or the other. NASCAR,,, I wonder, without limitations like restrictor plates, Webers or Carb?

Then of course the next logical step would be, Webers or dual carbs for an "absolute power" application, like the Bonneville Salt flats.

Tom, isn't Kirkham considering a Salt Flat run(s) in the future? Whats your game plan for induction?

[RICK LAKE]

hamster427 Brain if you are building a motor with webers in mind, you don't want to run a carb camshaft. There will be too much reversion. With the right setup and carbs you can make 10-35 hp over a single carb motor. You didn't say what the max rpm or cubes of the motor would be? A set of 48mm webers will get you to the 8,000 rpm range before falling. A carb will still make more power topend. This is on a small block ONLY. A 427 FE will run out of air in the 6,500 to 6,700 rpms with 48mm. Mid range torque is up about 20-30 ft of torque and hp about 10-35 hp. Another big thing is the exhaust on your car. It can cost you any where from 10-50 HP and torque You need back pressure in the 1-2.5 + pressure reading in your power band between max torque and HP.
Has far as webers on lemans car, Shelby went to single carb for the simple issues of less moving parts to have problems with and the bigger issue GAS MILEAGE. Every time you hit the pedal with Obergs or Webers the accellerator pump dumps gas into the motor, 4 pumps, 4 carbs that alot of fuel wasted. 1 carb, 1 or 2 pumps depending on the carb. Gas maileage did come into play back in the 60's. I beleive the the lemans cars where also limited to 6,500 rpms for the 24 hour race. I think they where allowed a higher rpm on the long straights.
Brain if you are looking for this kind of look, go with FI system and s setof TWM throttle bodies. They look like webers and run the same or better. The fi system also has a 10% adjustment for all different condition on weather. Webers are more for racing than street driving IMO. This is not saying that a setup of 58MM of Webers or Olbergs are not a work of beauty. When running right in a good FE motor, they sound great Rick L. Ps I left out the price on the webers and TWM setup. I hope you have deep pockets.

[RICK LAKE]

Excaliper Ernie Tony S cobra ran weber carbs and set some records. I also have pictures of the 390 liteweight"turd" car running webers.
Application has alot to do with running carbs or webers. Some of it was just plain a money issue. Look at a carb, say Holley because it's a simple carb. The kit we carried was a jet box with 10 jets higher and lower that what was in the car, 4 gaskets for the float bowls, 2 base gaskets, 2 accelerator fuel pumps and arms for switch between 35 and 50cc. It all fit in a tackle box for fishing. Look at webers, you have 4 carbs, multiply that my 4. Jets , jet holders, tubes, bore reducers. You have about $500.00 alone in this box, and the box is alot bigger too. Today we have recorders for every race we run, back then test and tune with luck. Today A/F meters for checking A/F during the run or race. EGT monitors for exhaust temps. internal pressure readings for blowby inside the motor, Back pressure in the exhaust, and the list goes on.
The other thing IMO is that a Weber or Olberg motor is not built the same as a carb motor. Different camshaft, high compression than a carb, less timing needed. Can also run on low octane gas without knocking or pre ignition problems. They are great carbs, the price is also great too. If you have the money and time, DO IT. IMO I stay with the simple, less moving parts way. Rick L.