3.0 liter rebuild

[kent olsen]

Question for Wayne or any other expert

This winter I plan to build up a 3.0L to replace the 2.7L in my 72 coupe.
My original idea came from Waynes rebuild book. I was looking for something over 220 HP to give me a 10:1 pwr/weight.

Waynes book shows two 3.0L rebuilds. One with about 9.5:1 and the other a little over 10:1 compression ratio.

My question is could you make a little over 220 HP and still run regular gas? Or should I consider 3.2L pistons/cylinders with less compression to give the same HP on regular gas?

[efhughes3]

I'm not about to answer this question Kent, you've got some other with great talent around here. But, I'm sure they're going to ask: what octane fuel do you have regular access to? To me, 220HP seems pretty reasonable on decent pump gas. You can always twin plug while you're at it to take that issue pretty much out of your concern bucket. What's your budget?

[euro911sc]

If you took a base 930/10 SC motor with 9.8:1 pistons and slapped headers/SSis and a nice muffler you might get about 210-220 out it with no mods and on pump gas.

Or you could make it 3.2SS if you put some $$s toward it...

-michael

[kent olsen]

I have European headers, webers and an M & K muffler that I plan on swapping from my 2.7L. I think with a better cam I might be in the ballpark with a basic rebuild.

I hope to do this myself and I'm hoping to get by with around $6k.

[Eagledriver]

With what you have you can get 230 or so with your stock cams and 9.3 CIS pistons. If you use 39mm ports, 46mm carbs, and more aggressive cams with appropriate pistons you'll be at 250 or more. We have several Toyo spec cars in the 240 range with euro CIS pistons, stock cams, and pump gas. They do have racing muffler's that will do better than the M and K though.

-Andy

[kent olsen]

eagle driver

Is the toyo spec you mention an SCCA class on toyo tires?

I've heard that "S" cams or "964" cams are a popular choice as well.

With the price of gas getting crazy I was wondering about the lower compression or going to 3.2L p/c to stay with regular gas.

Either way I still would like the 220-240hp range.

What kind of eagle are you driving?

[jhelgesen]

Andy, do you have any ideas on the set up on the weber 46's you guys are running with the stock cams and cis pistons? Interested in venturi size. I've got the stock 79 3.0 and 46's, headers and race mufflers.

[Eagledriver]

John,

I'm currently using 46mm PMO carbs. The vents are 38mm the jets are 155 main, 55 idle, 190 air correction and F11 emulsion tubes.

I was running 46mm webers last year with 35mm vents, 150 mains, 180 air correction, F3 emulsion tubes, and 60 idle jets.

The PMO settings were dyno tuned for a similiar engine. The Weber settings were just a guess but seemed to work fine.

The Toyo spec class is a small group (25ish) of racers in the Porsche Racing Club in northern California. www.porscheracingclub.com links to our class

-Andy

[Eagledriver]

Forgot to mention that most of our class is using 36mm venturies on either 40 or 46mm Webers. They seem to get max power without drivablility problems.

-Andy

[jhelgesen]

Thanks Andy, I'm pretty similar with my 46 setup, except I have 42mm venturies (as I got them) and it doesn't accelerate as well as I think it should. I'll order a set of smaller venturies and also swap to the taller manifolds.

Thanks for the info!