3.4 wish list
 

I'm putting together a wish list for a new track/race motor. I'd like to do a 3.4. Can someone please tell me the advantages of starting from either a 3.0 or 3.2. I pretty sure the 3.0 would be a short stroke. Just looking for specs and any info I can get. Couple of things I want that might make a difference. If it matters, I'm planning to run PMO 50 carbs and higher compression with race gas, so more agressive cams, etc are fine. I'd like to see around 300hp, but not if that means it needs to be freshed up on a yearly basis.

This is going to be a "on the shelf" motor. I'll buy parts as I can afford them and put them on the shelf. Build it when I have everything I need.

Thanks in advance.

The most common way to build a 3.4 is to use 98mm P/Cs and the 3.2 crank and rods. If you start with a 3.2 you'll be ahead on the crank and rods. You'll need to get a little creative with the 3.2 distributor on a carb'd engine (needs mechanical advance), but it's nothing that hasn't been overcome before.

When I was going to build a 3.4 I got a 2.7RS distributor, and a new brass gear for the front crank on the 3.2 crankshaft since the two gears have to match and finally broke down and bought new P/C's 98mm Mahles, had new custom ground cams done(still for sale) and heads redone with new stainless steel valves, all new springs, rockers etc. . Expensive, but you only want to do your motor once. Jim

I built mine off of a 3.2 (74.4 crank and good heads). It is a mild "race motor" and makes 285 at the wheels. So your HP needs are well with in reach. I believe Chris Striet built his big bore motor off of a 3.0 (70.4 crank) and it makes great power too.

The 3.2 heads flow very well for stock heads.

John give me a shout or email if you want to discuss in more detail. I will gladly tell you what I would do differently this time around.

Cheers

Jeff, do you think you could talk about what you'd do differently if you built it the second time around?

Like barney911rs I'm thinking about going up to 3.4L (but running pump gas) when I do my engine rebuild. My wish list is something like this:

98mm JE Pistons w/ 10:1 or so compression
Raceware headstuds
Twin-plugged heads
PMO ITBs & Tec-3r
cams (?)

The differences I would make are based on the fact that I would want the motor to serve a different use. I built this one as a hot street motor and this time I would move closer to a race motor....

I would have used 100mm Nickie slip ins or 102's and gotten either a 3.5 (no case work) or a 3.7.

I would have used a larger cam than the DC44 I used, but it fits the initial requirements nicely.

I would go from 1 5/8 to 1.75 on the headers with the bigger motor.

I would also have looked at aftermarket rods to use with the larger 100/102 pistons.

I am not sure how much more power I would have got, but.....

If I wanted a more "race" 3.4 I would have went with a bigger cam, maybe even more compression and the 1.75 headers.

cheers

i thought the 3L had a 74.4mm stroke?

I, too, want to build a 3.4 Short-Stroke one of these days. 101x70.4, 911SC Crank. Nickies Cylinders and case machine work required with 101's (100s I would recommend Nickies, and no machine work required, but that's a 3.3L).

The motor I will do for my next 911 would be a 3.6 destroked and bored to create 3.5L. 103 x 70.4 (911SC Crankshaft). 3520cc, 8000rpm banshee. More expensive than the "standard" 3.4, mostly because of the Nickies cylinders.

The standard 3.4 is a 98x74.4 using a 3.2 Carrera. 3356cc. I recommend cross-drilling the crankshaft and shuffle-pinning the case if you are going to be turning these R's. ARP rod bolts. Aftermarket headstuds (ARP, etc.). 10.5:1 compression, sounds like you want a race cam with those 50PMO's, twin plug ignition, preferably distributor ($$), but crankfire if you only want to spend $. In Porsche-speak, "$" means about a thousand bucks, ie., "I just broke a head stud, motor rebuild, $$$$$" :D

1.75" headers if you're racing.

I have both 3.0 and 3.2 perfect cases, crankshafts, Big-Port 911SC and 3.2 heads, other parts, etc., and can recommend a source or obtain anything else you will need.

PS-Facey, the 3.2 has a 74.4mm stroke, the 3.0 has a 70.4mm stroke. Remember, the way you figure out displacement is 6 * pi * stroke * (half the bore) squared . :)

Wouldn't one advantage of using the SC crank and doing a short stroke be a little more RPM? Not looking for F1 stuff. What sort of RPM could I expect? I'm running a conservative 7200 with my 2.7. I've know lots of guys running 8000 with 2.9's I'm planning to use better rods and bolts as I'd rather pay more upfront then have to fix something stupid down the line becuase I got cheap.

Yes, John, the SC crank is more durable at high RPM...hence my desires to build a 101x70.4 (3.4) or 103x70.4 (3.5) using a 3.0SC crank in a bored-out 3.2 or 3.6. With GT3 Titanium rods (I have a good connection for them) you could see a reliable 8300-8500. With 3.0SC rods & ARP bolts or Carrillos w/ SPS bolts (steel) I would keep it around 8000 or so.

If I really had my way this would be by "3.5 wish list":
-3.6 Case, shuffle-pinned
-3.0SC Crank, balanced and cross-drilled
-GT3 Titanium Rods, in the 130mm length (3.0SC is 127.8mm)
-Custom JE pistons and Nickies, 103mm, dry-film lubricant coatings on the piston skirts, ceramic thermal coating on the piston tops
-3.6 (twin-plugged at the factory) Heads with CNC port modifications & Titanium valve spring retainers
-DC100 or similar race cams, RSR forged rocker arms (I am reproducing these soon)...rockers coated with DLC (Casidiam 'diamond-like carbon')
-Jenvey ITB's, TEC engine management, 993 dual-plug distributor
-Full race exhaust (I make my own headers), 321 Stainless

A 3.2 crank can spin to 8000 or so, but the rod angularity poses reliability issues, and the rod bolts are 9mm, not 10mm like the 3.0's. Also the 3.2 Carrera base will have higher piston friction because the piston is being side-loaded very hard. If you can imagine the crank and rod turning, the longer the rod length relative to the stroke, the more the rod can 'pivot' on the piston pin without side-loading the piston. 3.2 standard rod length to stroke ratio (127.0/74.4mm)=1.71. A 3.0SC (127.8/70.4mm)=1.82. The ideal is close to 2.00:1; a good example is the 906 2.0L revvers with 1.97:1 (130/66) that will live for days at 9000

sry, a little OT, but whats the 3.3L turbo crank? 3L based or 3.2?

3.3L turbo crank (1978 - 89) is used in the 3.2L (1984- 1989) engine.

Don't mean to hijack, but...
I have just finished building a 3.5 and am wondering if I made a mistake by not upgrading my oil pump. I started with an '86 3.2 with 130k on the odometer. The oil pressure looked strong before before I pulled the engine from the donor and the internals were surprisingly like new (what kind of idiot tears down and rebuilds a perfectly good engine:confused:).

The build is as follows:
100mm Mahle RSR p & c's 10.5:1 stated comp.( actual measured compression is 9.8:1)
Crank balanced with center oiling mod
ARP rod bolts and head studs
GE60 cams and JWE valve springs
Twin plugged heads
Steve Weiner's custom GHL heat exchangers with custom Monty muffler

It's going to JWE next week for ITB's, Motec, 993 resonance chamber on top of the ITB's, and dyno work. So, with all of the time, effort and $ put into this project would I be wise to crack the case open and put in a 930 or GT-3 oil pump in before I go any further?

TIA for your thoughts,
Steve

If you can swing the extra cost, Pauter rods will shave a decent amount of mass. Not as much as titanium rods, but but my 6 Pauter rods weigh the same as 5 stock 930 rods.

Steve, a 930/GT3 pump is technically 'better', but the 3.2 pump is a fine pump for a naturally-aspirated engine, and it's a big PITA to take it back down. I think you'll be fine. :)

This looks like a nice addition to any 3.4 wish list...

Carrillo 3.2 L Rods (not mine)

Ebay #120306086185

http://cgi.ebay.com/ebaymotors/Carrillo-Con-Rods-Porsche-911-Carrera-Turbo-RS-RSR-962_W0QQitemZ120306086185QQcmdZViewItem?hash=item1 20306086185&_trksid=p3911.c0.m14&_trkparms=72%3A72 7%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

David do you know the part weight on the Pauter rods? The carrilos don't seem any lighter than stock.....

Cheers

596 grams

Isn't the main reason for using Carrillo and Pauter strength. Any reduced mass is a bonus. Ti rods would be nice, wonder if I can Warren Buffet to sponsor my engine.

lets say a set of ti rods is only about two sets of pauters...;) and only 420g apiece.