What engine to use for performance mods.

[hbrand]

Which engine and modifications would I want to use:

Will go in an early 911 coupe, 1966 to 1972, with carburettors, super unleaded gasoline, no turbo, max 250 HP , good torque over a wide range of RPM's, for street use, no computers, as simple as possible.

thanks, harold

[bigrubberjeep]

3.2 W/Carbs / SSI / High flow mufler / dual plug

[Grady Clay]

Harold,

For lightweight high performance a 2.8S built on a 7R case, twin plug, 10.3:1 CR will give you ~250 HP with good reliability. There is lots on this forum, do some searching.

Do you have a car? There is a significant difference between a short wheel base 911 (’68 and earlier) and the long wheel base ’69 and later.

The advantage of starting with a 3.0 is that it is more robust and you can get to 3.5 and larger. It is a somewhat heavier engine.

Best,
Grady

[bob tilton]

harold - thanks for posting this question. i need to figure out what to stuff into the back of my car as it is the next project.

[JTH 36]

I'm running a 72 E body with a 3.2 on Webers and SSI's. It dynoed at 220 HP and 213 ft lbs of torque at the wheels. A very fun ride!.

Jeff

[hbrand]

I am looking to buy an early 911 coupe, then beef up the engine, work out a super a/c system, install an MP3 player with power amp, and then use this car everyday.
At least thats the plan, have enough money in bank.

thanks, harold

[hbrand]

JTH 36!! what webers did you use, how is engine idle, response and power band??

thanks, harold

[Grady Clay]

Bob,

I have been wondering what to put in my old ’68 when it goes back into service in three years. I think I’m going to work the “lightweight” issue to the extreme (engine only.)

That 911 has had several dozen engines in it since new. I think the original engine doesn’t have more than 40K; it’s in the 911 now. I put a 3.0 in it once and the weight was very noticeable. With a 2.8S it weighs 2220# with a full tank of gas and all the stuff in the trunk.

For an outrageous 2.8S lightweight I’ll use Titanium hardware, fiberglass tin, 906 mag 46IDAs and manifolds, all mag castings, and leave off everything unnecessary.

I suppose I could put on the ‘69S alu decklid and license panel.

Best,
Grady

[Randy Webb]

the 3.2 heads flow a lot better.

Grady - have you figured out how PAG cut the wt. so much in their racing engine - 904??

[fintstone]

Harold. I had similar requirements. For a daily driver that does not have to be smogged... a fresh, upgraded 3.0 with SSIs, 20/21 cams, and early CIS seems to be a great combination to me. I like mine. I believe the CIS gives it better mileage and drivability than carbs.

[aigel]

Have you ever experienced a 3.6 with carbs? I have ridden in an early car with a Jerry Woods built carbureted 3.6 What a MONSTER! I'd go that route. Very rugged power (long life), flat torque curve, comes twin plugged from the factory, and comparable in price to a well built short stroke 3.2 etc.

George

[Grady Clay]

Randy,

A 587/3 engine wasn’t particularly light when compared to a 901 and was downright heavy compared to a pushrod 616. All those gears and shafts for the cams were steel. The case and heads were massive aluminum castings.

When you compare a 906 to a 901 the difference is mostly in materials; magnesium crankcase compared to aluminum, titanium rods, lighter pistons and rockers, lighter flywheel and pulley, fiberglass tin, and even titanium hardware to hold the fiberglass in place. There were some extreme measures like the smaller cam nuts and eventually titanium jackshaft and aluminum cam sprockets on the 935.

To build the lightest hot 911 I would use the 7R case and replace all of the appropriate hardware with titanium. Inside would be 935 lightweight parts. Fiberglass tin, 906 mag intake manifolds, 46IDAs, early mag valve covers, no distributor or drive gear. Of course there are some things necessary that add some weight over a normal 2.7; twin plugs, dual oiling for the cams and rockers and a larger oil pump. The RSR 2.8 P&Cs are slightly lighter than 2.7.

Of course the old adage applies: “How light do you want it, how much money do you want to spend?”

I agree that a 3.x is a good choice in a normal ’74 and later where the percent weight penalty isn’t as great. As soon as you talk about a “lightweight” the engine and suspension mass become critical. The engine weight is exceedingly important in a SWB 911.

Best,
Grady

[JTH 36]

"JTH 36!! what webers did you use, how is engine idle, response and power band??"
thanks, harold

I'm running 40 IDA's with 38 Venturis. You are really at the max with 40s on a 3.2 but it runs great. It idles well and the throttle response is amazing. It has a very flat tourqe curve so it is very easy to drive around town, but when you get on it all heck breaks loose.

It is alot of fun to drive. It is actually easier to drive than my 2.7 MFI Car.

[Randy Webb]

Grady -- here is the Ludvigson tidbit I was thinking of. -- Ch.17 of the old ed. I think.

"In building the 904, the use of Mg and Ti cut the weight of the 911 from 405 lbs. to only 286 lbs. (119 lbs. saved)"

-- That is a huge wt. savings!

IF you do build a lighter engine, be sure to give us all a blow by blow description. - Best, Randy

[Grady Clay]

Randy,

You are right about the weights but Ludvigsen was comparing 901/01 to 906 (901/20.) I think the confusion lies in the fact that Porsche ran the early six in the Factory 904s in ’65. When Porsche designed the 904, they were intending to use the six. The engine wasn’t ready so the 904 got the 587/3 4-cam, 4-cylinder.

Ludvigsen 1st ed. p 429.
“Perhaps the most awesome aspect of the [906] project was the demand for more lightness, for the 405 pound Type 901/01 six was already noteworthy for its extensive use of aluminum. How was such an engine to be made lighter? The answer was surprisingly simple: change the aluminum parts to magnesium and the steel parts to titanium. The result was a reliable racing engine that weighed only 286 pounds – less, remarkably, than the four that powered the 904.”

This is exactly the same language in the 2nd ed. Vol 1, p 366.


Today we have even more “trick” parts available from the later 911s, 935s, 956s, and 962s. I would guess there is another 30# that could be shed. That makes a 2808 cc, 250 HP, 250# reliable street engine – remarkable.

Best,
Grady

[Randy Webb]

That would be great -- when you do it, maybe you can list the $/lb. saved figures -- I know things like Ti rods have come down in price but are not what I'd call cheap.