911s and V motors

[kstar]

Well, it's no suprise to anyone here that the V configuration re motor design is as venerable as the 911 and its boxer layout.

We have Mercedes, Ferrari and even Porsche showing many years of V based engine development.

And, the racing history of V type motors is also as venerable as Porsche's racing heritage, with the boxer type motor. And I am not just referring to Nascar.

The newest Porsche supercar sports the V10.

But, I still have a problem when I look into a 911 engine bay and see that large circular air filter housing (especially if it is chromed!) probably on top of a Holley carb . . . and engine dressing aesthetics that look great in a vintage Camero or Mustang, but ackward in a 911.

I have nothing against a 911 V8 conversion, especially the ones that are done with a Porsche "sensibility".

I think with black crinkle finish on the valve covers and an eight stack Weber type carb, the look, at least, would be more sympathetic to my purist side.

I have seen the eight tube carb set-up, but who makes it and how much does it cost? Sorry for a probably stupid question.

I like the sound of Webers on a flat-six - that sucking howl is intoxicating.

An aluminum V8 done properly with eight intake tubes a la Weber would really howl . . . and the motor should look quasi-correct.

BR,

Kurt

P.S.: Still waiting for the first V8 TT Cayenne motor in a 911 "conversion".

Maybe Porsche will beat us to the punch?

[kstar]

Well, I was hoping for a response on this from hopefully the sympathetic 911V8 crowd or at least the Church of the Flat Six group!

I guess I am wondering what carb set-up would work on a V8 - the type with eight stacks - I think Ferrari used these at some point and I assume Weber was the maker?

Any help?

TIA.

BR,

Kurt

[TC 911]

Back when I was into street rods, Inglese (sp?) mad some fancy multi weber manifolds for Chevy and Ford V8s. I am not sure if they are still in business.

Several aftermarket electronic fuel injection companies are converting old Hilborn mechanical fuel injection systems to electronic injection. You get the period correct look of velocity stacks with modern day fuel/sprk management. Hilborn is still in business and has a web site. BDS (Blower Drive Service) was doing this conversion also. I also remember seeing a car with the tuned stack injection manifold that was converted by Force Fuel Injection. They used to have a websight also.

I have Accel GenVII fuel injection on a very rowdy small block chevy.

[Pete Pranger]

I like to think there's a reason there aren't too many weber type set ups on v8s. If I remember correctly they had a brief popularity amongst the ford (cobra) crowd. There were some drag cars that used the various hilborn, crower, etc... set-ups, but they were a mechanical injection set up that wasn't very practical for the street, but they looked sweet on a BBC with the tuned velocity stacks. Some of these have been converted to EFI as previously noted, but it's not cheap.

On a SBC there are a lot of very effective intake and fuel delivery combinations, ranging from a few hundred to several thousand. I am still a pretty big advocate of the four barrel carb. For the money, you just can't argue with the performance. This when coupled with the simplicity and reliability makes it the induction setup of choice for me.

I don't have any fantasy about my motor ever being mistaken for a flat 6. I am building it because I can get the best reliability and all around performance for the money this way. I agree that what looks good in my 69 camaro won't have the same appeal in my porsche. I have never been a big fan of chrome anyway. I don't think you will be able to see much of my engine because I am going to mate the intake to the opening in my turbo tail. This way I will get only fresh, cool air to my motor. For me anyway, performance overrides aesthetics.

Pete

[kstar]

Pete:

I thank you and TC for your help!

I was once a purist, but now I guess I am torn between two worlds.

I can't argue (and do agree) that the SBC option with AL heads and such is a great option for a street and even tracked 911.

I think the above statement sets me way apart from many 911 guys. They will argue the flat six is far superior in so many ways, especially weight and CG figures . . . but "real world" evidence says that these are simply not significant factors in most cases.

Heck, some of the V motor facts are in Porsche's own backyard!

The SBC is not a lumpy anchor, crude motor. But I understand how some "flat folks" might think so . . . too much Kool Aid . . .

Like you, Pete, I think we can both agree re a "utlity" function of as motor. If there is another option to the sometimes "exspenive to get horsepower from" 911 motor than I am all ears.

My angle is that it would be cool to build a project 911 with a V8 that somehow touched the senses of the 911 flat six folks. Something that was a potent performer that would tempt them to the "other side". Eight stacks and a "pretty" looking motor might be a benefit. As we probably know, performance will speak for itself.

Heck, even Jack is starting to take a fancy to the Cayenne!

What's funny re the early car group (of which I consider myself a member having built an expensive 3.2 MFI hot rod that I still miss) is the way that us folks can blank out the rest of "reality".

If Porsche builds a V8 911, I can already hear the protests and disgust, even if the new car performs better in every respect.

Sometimes one must back up a bit from the forest and look at the trees. 356 guys eventually accepted the 911 (well, some at least!) and 911 guys will probably accept the 996 series at some point. These 996 based cars have won some significant races by privateers! And the GT2 and GT3RS do not suck.

I don't know if I should build a classic V8 911 or just wait for Porsche to build a better and more modern V8 911 . . .

More than my 2¢ worth!

Best,

Kurt

[ttweed]

Originally posted by kurtstarnes
I have seen the eight tube carb set-up, but who makes it and how much does it cost?

Kurt-
I recently saw just such a setup on a '65 Ford GT40 MkII that is for sale at Symbolic Motors. It had a 427 Ford with Webers and individual airhorns that looked very purposeful, combined with the snaking stainless headers.

This setup would not be cheap. I have seen it listed as an option on some of the GT40 clone sites at about $8,000. You might talk to these guys in CT about such a setup.

The sound when this car fired up and drove away was incredible!

TT

[masraum]

Kurt, I agree. an SBC in a 911 isn't that bad. I like the way the flat 6 runs in my car, but I'm a GM guy too. Yes, Webers or old injection would look the part and be aesthetically pleasing, but in keeping with the spirit it seems one of the modern aftermarket computerized injection systems would be better.

[Lukesportsman]

Don't tell me that we actually have a "small" shift on this board. I've only been a member for a short time, but have monitored it for sometime. Until these two recent V8 topics, I've never seen such open minded views of this topic. Let's face it, a 3.6 is not quite stock in a swb either, though it does qualify it for PCA and that could be very important to one. The cubic inch versus sophistication argument doesn't carry much weight with me since Porsche, Ferrari and Lambo each seem to gain cc's each generation. Keeping a car all in the family is a legit argument but might not win out in the end. Street vs. track would seem to be the over riding factor. 1 mod'd 930 $$$ = 2 non turbos $$$ (1 SC for the track and 1 V8 conversion for making Hondas cry) :-) No offense intended for any! Everyone must enjoy their own cars the way they wish. They are just cars, though great ones.

[isaacyoon]

thats one beautiful looking engine....

[jluetjen]

OK; Here's a site with some excellent incar sights and sounds from one of the original GT40's with an F'ing (Ford) V8 with I assume the 4x2bbl weber set-up. Mighty nice if you ask me!


Also here's another site with some excellent sights and sounds of some other F'ing (Ferrari in this case) V engines.

Enjoy!

[jluetjen]

Let me now stand up for the good ole' Porsche Boxer 6. Granted, a V8 configuration provides a lot of packing benefits over almost any other configuration due to the resulting engine taking up basically a cube shaped volume. So for a HP/total engine volume perspective, a V8 has a lot going for it. I'm sure this certainly contributed to the decades long sucess of the Cosworth DFV family.

But the air cooled boxer 6 has some things going for it too which certainly add's to the 911 experience!
1) A 180 degree boxer benefits from exhaust tuning that it not possible in a 90 degree V8 with a 90 degree crank. This helps the engine provide more HP per cubic inch.
2) A boxer engine is by definition internally balanced which makes the engine smoother and allows the bottom end to rev higher. I'm not aware of many traditional Detroit V8's (excluding the recent 32 valve versions) which can rev to 7000+ right out of the box. V8's with 90 degree cranks are smooth, but loose the exhaust scavenging benefits. V8's with 180 degree cranks (like Cossies and Ferraris) get the exhaust scavenging, but have have some nasty vibrations.
3) Within the performance envelope that most engines operate, air cooling takes less HP then water cooling since less energy is absorbed by fan then by the pump. ( Admittedly air cooled engines are also noisier then water cooled engines).

So let's not overlook the design trade-off's that the designer of the 911 made which defined the 911!

[CamB]

The biggest benefit to a SBC is displacement, IMHO. I've got a not inexpensive 85hp a litre in a flat 6. If it was a 350 Chevy it would be 490hp.

This equation is made worse (for the F6) because the parts to make 85hp/litre in an SBC are semi-mass produced and thus cheap(ish). I can't get past pushrods though.

[Pete Pranger]

Not to step on anyone's toes here, but I don't necessarily agree with the points made by John (jleutjen).

On your first point concerning the exhaust tuning, my experience racing the flat six is almost none, so perhaps you could elaborate a little more on this one. I am afraid I'm not on the same page as you here.

I think my terminology is a little diffferent from yours here. I define "internally balanced" as a reciprocating assembly that is balanced (internally) without the need for external weights (harmonic balancer and flywheel). This is determined by the length of the stroke (the throws on the crank) and the size (weight) of the counter weights. I think what you are referring to is the fact that the cylinders are directly opposed. Personally I have never heard of an engine being "balanced" by the cylinder orientation, but I am open to new ideas. This idea however would make a radial engine almost perfectly balanced I guess. This however has very little if anything to do with the RPM potential of an engine. RPM potential is determined by several factors; the ability to flow air at that speed through head and camshaft design, the other being the reciprocating mass. The lighter the recip assembly, the faster it can spin (all things being equal) I will use a modern day sportbike engine as an example. They use an inline 4 that spins to insane levels (14,000 rpm in some cases) this would be considered to be "more" out of balance in its design than a V motor. The effects of the weight of the recip assembly can be seen when a porsche flat six is compared to an aircraft flat six. Your motor (I'll assume a 3.6 ) has roughly 200ci and Lycoming makes a 540 ci flat six. On a good day you might see 5000rpm on the A/C engine (discounting the propellers operational speed which actually limits the engine to 2800 rpm) this is due to the fact that as you increase displacement the size and therefore weight of internal components increase. In theory if you biult 2 "equal" motors a 2.0 would be able to sustain a higher rpm level than a 3.6. You are correct, the american v8's are usually limited to 5000 rpm (or so) but that is by the design of the components. Take a truck motor and swap out the cam, heads and intake (to support the airflow-higher rpm) and you can reliably see 7000 with no modification to the lower end.

We could argue the merits of air vs water cooling all day. In response to the pump/fan drag, the engine driven fan has all but been replaced by the advent of good motors for the electric fans. I have no idea what the pump takes to drive, but I will gladly give up a few hp for the combustion chamber design that water cooling allows.

One other thing about the v8 is that with the addional 2 cylinders, you get a better overlap of power cycles which helps with vibrations and power production.

Pete

[afterburn 549]

syan back i think i'm gonna hurl aaaaagggggg !!

[jluetjen]

On your first point concerning the exhaust tuning, my experience racing the flat six is almost none, so perhaps you could elaborate a little more on this one. I am afraid I'm not on the same page as you here.

In a flat 6, an inline 4 or a V8 with a 180 degree crank, the exhaust pulses are collected in the exhaust collecter at a regular frequency. For example every 240 degrees of crank rotation, a pulse from one bank of a 911 motor arrives at the collector. The same occurs at in the other motors I mentioned every 180 degrees (with a 4-1 manifold) or 360 degrees (with a 4-2-1 manifold). In a standard Detroit V8 with a 90 degree crank, that doesn't happen since the pulses are uneven unless "180 degree headers" are used. BTW, the headers on the GT40 are most like "180 degree headers".

As far as the balancing is concerned, 911's hardly need counterweights on the crank -- many folks race motors (up to 7000 RPM) with the early T cranks which are not counterweighted. They can do this since the opposing pistons essentially counterweight each other. I don't have the ability to do the modelling, but I doubt that you can do that with with a Detroit V8. As far as a crank damper is concerned, 911 motors don't need them. While balance contributes to the RPM potential, we agree that it is not by any stretch of the imagination the only, nor even primary constraint. And like all factors of the engine design, it's how you put the compromises together. As you point out, Superbike engines go down a different path and use short strokes and light components (a benefit of generally being only about 1 liter) to good use to turn 14K RPM or more.

My point was that the 911 designers chose to follow a path that stressed a low CG and high specific output when they designed the 911 package. They chose to give up packaging efficiency (they weren't using the space behind the rear axle in a 911 for anything anyhow! ) as their trade-off. While people have certainly put Detroit V8's into the back of a 911, and the the HP will certainly move the car down a drag strip in a straight line fast. I doubt that the engine swap will help the resulting package go around the Nurburgring faster then this guy is using the original 911 concept.

At the end of the day, it's your car. You can put a Detroit V8 into. It won't be worth as much and personally, I wouldn't appreciate it. Put that same V8 into the back of a GT40 or into the front of a TVR on the other hand...

(Note -- The Nurburgring video is a slow download)

[emcon5]

TWM makes a nice throttle body setup for V8s. This one is for a small block Chevy:



Pretty.

Tom

[SteveStromberg]

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[SteveStromberg]

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