'87 3.4 conversion worth it?

Thunderbone · 08-23-2002, 11:47 AM

I must admit I was really nervous when I fired up the Carerra with its new 3.4 liter heart. Was I going to be happy, or angry. Six months of waiting and $8300 later I find myself petrified as I turn the key. I think about all that I did:flowing the intake; reworking the heads, then going with EBS' sport springs and titanium collars; P's&C's from EBS, 20/21 cams from Webcam, new rocker arms and shafts. New shocks, corner balanced. New CV boots.Did I do enough? Did I do too much? ****, I'm scared!

The motor lights and I know instantly that there is something different. The 911 has a throatier sound. Okay, I say, that's a good sign-- maybe this will be a good thing. It is a real good thing. The car totally rocks, even with the stock control unit in it. In 1500 miles the car will go on the dyno and have a new chip crafted, then I can put a horsepower number to this adventure. This is a new car. I'm blown away.

pbs911 · pbs911's Garage

Great story, Post some pics and the dyno sheet when you get it. It sounds like a great project and alternative to the 3.6 transplant.

Milu · 08-23-2002, 12:12 PM

Sounds great.

I think that if you add a MAF and a better exhaust to help it breath better before the chip and turbo tie rods with aeroquip hoses for the brakes you will have a killer street car.

And then...........the weight reduction programme!

Sorry, I got carried away. It's your car but I just love this kind of 911!

Wil Ferch · 08-23-2002, 12:47 PM

Guys:
I have a close friend with a (supposedly) 3.4L conversion done to his 85 wide-body. I collect 3.2 Carrera dyno runs...and his showed very good mid-range torque and hp....way out of line with other 3.2's. Having peeked our interest, and after many phone calls and investigations later, we find his car had ( at one time) been converted by Stahl motors in Florida, presumably as a 3.4 ! We had no idea!
Anyway, if / when you get dyno runs, please indicate whether you used a DynoJet 248C, and if the run was ( hopefully) corrected to SAE standard conditions...so we can play the comparison game !!
---Wil Ferch

Thunderbone · 08-23-2002, 02:15 PM

Milu

I have the SSI exhaust, the update that's really retro as you know. I actually considered the MAF but decided that 1-2 HP for $400 was too much money for not enough ponies. And then The Mechanic gets this idea about using an MAF out of a V-8 BMW proclaiming that it would be better and cheaper than what's
available out there. He claims 5-10% gains. Let's see, on the '88 Carerra he is going to put this on has 217HP that means a HP gain between 10.8HP to 21.7HP..he's been too long at the degreaser I bet he's wrong. He bets and smiles that look that tells me I just lost. This is the same look I got when I wanted to Extrudehone my intake. My intake now bears the welds that show the job was done correctly and he was right. So maybe I will get an MAF. The Mechanic, being who he his, may do this MAF deal next week...or next year I guess it depends on how quickly he want to collect on the bet. At any rate, I'll get my car on the dyno here in a couple of weeks and publish the results.

T.

emcon5 · emcon5's Garage

Sounds nice.

I remember reading somewhere that SSI's were on the edge of being too small for a 3.2, and way too small for a 3.6, I know it would suck to have to spend more on an exhaust at this point in your project, but I would hate to see you miss out on some extra power.

Tom

jyl · jyl's Garage

T-bone,

Could you say a little more about the mods you did? I'm particularly interested in the Extrudehoned intake and the flowed/ported heads, as I don't see many posts from members who've done those.

Interesting stuff would be like how much it cost, what gains are you expecting, what was done, what your thought process was in deciding to do it.

Thanks - from a stock 3.2 that would like, someday, to Be More.

Thunderbone · 08-23-2002, 08:17 PM

emcon5

Somewhere I came across info that said the SSI's would just be able to flow a 3.4..or maybe I dreamed I read it and made it okay. Unlike the 964, I still have stock size valves, I'm telling myself this keeps me within the SSI'S capacity. I'll ask The Mechanic if he thinks it could be an issue.

Thunderbone · 08-23-2002, 09:10 PM

jyl:

I was all fired up and ready to Extrudehone the intake. The Mechanic talked me out of it. He said the intake had to be split apart, the runners flowed and then rewelded to do the work correctly. He was absolutely right. Extrudehone is this pasty goo that is forced through pipes to smooth them out. So if I smooth out all my intake runners than they will all be smoothed, but still flow at different levels. The cost was about the same.

The heads on a 3.2 Carerra flow very well and don't require porting, according to Bruce Anderson. If you want to trick the heads, you twin plug them and you can run higher compression pistons.

The whole deal cost $8300. It seemed reasonable to me, although I never did shop it. I got what I wanted: a little more low-end grunt, power that rocks from 3500 to redline, a true understanding of what thottle response really means.

Milu · 08-24-2002, 03:59 AM

Results from MAF seem to vary from installation to installation, but your mechanic seems to know his stuff.

I'm always sceptical about hp measurement but with the MAF I'll bet you'd end up at 280 bhp measured with a g-tech or 260 at the wheels on a dyno with the torque to match.

CamB · CamB's Garage

Quote:

Originally posted by emcon5
Sounds nice.

I remember reading somewhere that SSI's were on the edge of being too small for a 3.2, and way too small for a 3.6, I know it would suck to have to spend more on an exhaust at this point in your project, but I would hate to see you miss out on some extra power.

Tom

I have SSIs with my 3.2 (same as a 3.4 but with the SC crank not a Carrera crank). I also have a standard muffler.

With early S cams, I have 270hp (245hp at the wheels), so it can't be holding me back too much

Chuck Moreland · 08-25-2002, 07:23 PM

If you are seriously considering a MAF, why not do it right and go for carbs? It might cost a few pennies more but you get some serious HP, not just a few extra ponnies like with the MAF.

On a dollars/HP basis you are way ahead with carbs.

89911 · 08-26-2002, 04:07 AM

Quote:

Originally posted by Thunderbone
jyl:

I was all fired up and ready to Extrudehone the intake. The Mechanic talked me out of it. He said the intake had to be split apart, the runners flowed and then rewelded to do the work correctly. He was absolutely right. Extrudehone is this pasty goo that is forced through pipes to smooth them out. So if I smooth out all my intake runners than they will all be smoothed, but still flow at different levels. The cost was about the same.

.

I'd have to dissagree with this statement. After seeing The intakes of a 3.2 done by extrudehone on my brothers 87, the end product is perfect. They are located in the Pittsburgh area and my brother had a chance to meet with one of the heads out there and briefly see the plant. You are simplyfing there process also. They work on much challenging projects, (Aerospace, aviation, etc.) Beware of mechanics opinions as the absoulute truth!

Thunderbone · 08-26-2002, 12:27 PM

89911

Thanks for your input. Actually, my first choice was Extrudehone. However, when The Mechanic got in touch with their Southern California plant, he got annoyed when he couldn't get questions answered about how they balanced flows and did they have shops that he could talk to about the results of the process.

The price for either method turned out to be that same and Extrudehone had a pretty long turn-around time, so I went for the Frankenstein look. Did your 'bro get before/after flow results?

Thunderbone · 08-26-2002, 01:50 PM

CamB

You say your "3.2 motor is same as a 3.4, only with a SC crank instead of a Carerra crank" I thought the SC had 96 MM bores with a 72.4 crank. The Carerra has a 74.4 stroke (now) with 98 MM bores, giving it a displacement of just under 3.4 liters. So are you saying you have 98MM cylinders with the shorter stroke, revving that puppy to places I can't go?

Thunderbone.

CamB · CamB's Garage

Yep - I have an SC case, 70.4mm crank and 98mm p&c for 3,186cc.

I would love to report on how well it revs beyond 6000, but I'm still running it in (a strange concept given the car has been run to 7000 multiple times on the dyno while tuning).

The main reason I can probably rev higher than you is that I have stronger rod bolts - the SC doesn't have the same reputation for breaking them as the Carrera, plus I have ARP rod bolts.

I have had the limit set at 7000. That'll do.

Get yours run on the dyno - it should be gratifying and may highlight if you have any potential problem areas (overly lean or rich). This is mine (correction factor from hubs to flywheel is 1.10x, or assumes 9.1% loss).

New injectors and fuel pump - 250hp breached...

89911 · 08-26-2002, 07:08 PM

Quote:

Originally posted by Thunderbone
89911

The price for either method turned out to be that same and Extrudehone had a pretty long turn-around time, so I went for the Frankenstein look. Did your 'bro get before/after flow results?

Fortunately he had the opportunity to go to the place and talk to a human being. As far as result, no they don't provide any data and I doubt they ever would. This place is a multi-million dollar facility and this stuff is a side revunue. As far as your intakes, I would like to see how it could be done better be cutting and rewelding. How do the match up the seams in areas unreachable? In certain situations the extrudehone process seems like the only possible alternative. His price also was around $400. Sound about right? 89