3.0-Rebuild Experts: What HP is your guess?

[al lkosmal]

Gunter,
I have one of the G-Tech units. If you'd like to borrow it, let me know. Although you may not be able to use it until the big spring thaw.

Al

[dd74]

Originally posted by boxermania
I see that the topic has become interesting.....horsepower here and horsepower there.

What is a few horses amongst friends, of course you will see dyno differences, temperature corrections and certainly it is assumed that the engine is in a perfect state of tune.

For instance, the chart above with the AFR in the 12's from 5K on is losing output. It has been proven time and time again that depending on the engine configuration the best power is attained between 12.8 and 13.2. So based on my experience one could see some additional HP if the mixture is leaned out some.

Likewise the spark lead will always affect the HP, I remember early on when we use to "power tune" the cars, since it will position the fire in the cylinder when the most effort can be obtained from the downward stroke of the piston.

On the other hand, turbo cars typically run on the rich end to insure temperature control since these can get away fairly fast and then, Ouch!!!!!

I think that a couple of acceleration runs on third gear with a G-meter should give us a pretty good idea of where the subject car dials in......has anyone here done the G-meter?

Good points on the AFR.

A long time ago, I used the G-Tech, but only for timed runs to 60. The results were all over the place. My car clocked 0-60 in 6 seconds, then 8, then 7.5. Finally I gave up as I believed I was hurting my drivetrain and/or engine.

I ended up relying on a stopwatch.

[Gunter]

Many thanks to all.

Ralph, wow, many types of HP.

rdane: Thanks for the tip; I think a visit to the dyno is in order but, Fremont CA is too far. Is there one in WA?

It looks like consensus is around 230-240 at the crank, that's reasonable
An unknown factor is the distributor curve and the timing.
I am using a distributor from an '80 which worked really well on my 3.0 liter. I'll have to experiment with the timing.
Question: Will the dyno show anything about distributor curve and timing?
In other words: Can different settings on the timing, and mixture, be tried/adjusted right at the dyno?
Dyno test: Is there a technician at a dyno who can set optimal mixture and timing?

[Superman]

Originally posted by Carrera3.5L
Some of you guys are dreaming or use a very optimistic dyno...

A stock 3.2L Carrera motor makes in the mid-180's on a Dynojet and one that has been SW chipped with exhaust makes 200-205 whp all day long on a Dynojet, how would this motor make any more with CIS and pump gas?

A more accurate picture would have been a before and after on the same dyno, which would show you your improvements (which is more important than peak numbers).

For a guesstimate, 200 whp on a Dynojet 248C... The power improvement will still be noticeable and make the car more fun to drive...

Ralph

While I would agree that many folks are overly optimistic about horsepower expectations, but I regard the above as overly pessimistic. Porsche specified the 3-liter engine at 180 hp, and that's perhaps the LEAST you can expect, in stock form. My engine has been freshened and has cams. Its O2 sensor system has been unhooked and timing is advanced to 35 degrees full advance. It makes 205 hp at the crank (174 at the rear wheels) all day long.

I would expect my engine, with 98mm P&C's and 9.8:1 CR to make closer to 235.

[Gunter]

Super:
Unless I am mistaken, when the 15% formula is applied, Ralph comes in at 230-35 at the crank.

Is there a dyno in Seattle?

[rdane]

Most of us locally have used Carb Connection in Kirland. Contact info is in the NW section. And yes, you do tuning AFR tuning on the dyno.

[boxermania]

Gunter

When one gets time on a dyno there are a couple of options, a fixed price, which typically includes one base run and a second run to verify the first run. Some other operators might provide 3 runs, one base, one to verify and one to tweek fuel, timin, etc.

Or you can engage the dyno by the hour and you can do whatever you want.....generally you get the dyno operator but no tech to change fuel or timing settings.

However, there are some shops, like Imagine Auto in Kansas that part of their business is performance improvement kits. They have a Mustang 4 wheel drive dyno and not only will they dial in your car but also pretty much know what works and what doesn't.

[SC-targa]

Originally posted by Gunter
What numbers can I expect with this SS 3.2 I just finished:

Bottom is from an ’82, mild boat-tailing, standard 70.4mm crank.
CIS is from a ’78 with the larger intake runners.
Heads are ported to 39mm.
98mm P/C’s, 9.8:1 CR, CIS dome.
Cams are 964.
SSI’s with an M&K muffler.
I am keeping CIS and Bosch CDI.

What’s your guess? HP? Torque?
I

Sounds like a good engine. I agree with some others that HP figures are often misquoted and many chassis dynos appear to be a bit optomistic.

Remember that Porsche themselve, back in 74 with the 3.0 RS found that an MFI motor with the big overlap "S" cams and the old style tuned exhaust (equivalent to SSI's) needed a 9.8:1 compression to make 230 DIN HP, about 220 SAE net FWHP, I assume local Dynos should be measuring SAE net HP, not DIN.

A late model ROW 3.0 CIS with 9.8:1 pistons like yours made 204 DIN HP (~195 HP SAE net). Does anyone believe that with an SSI exhaust, CIS instead of MFI, softer, no overlap cams, that an SC engine will make 220 FWHP like the 3.0 RS motor made?

I don't. Let's be very generous and say it makes 215 FW SAE net HP and that the MFI and S cams are only worth 5HP. Then I'd guess gunter could make 7% more, or 230 SAE net FWHP (~195 RWHP)

Also recall that Porsche themselves didn't even pick up 15 when they boosted the Carrera RS 2.7 motor up to 3 liters until they upped the compression from 8.5 to 9.8:1.

Regards,

Jerry Kroeger

I would use that as my target for your motor. You've got much less radical cams in you engine, but you've had it boatailed and boosted the displacement by almost 7%

Had to edit some typos...

[Gunter]

Originally posted by rdane
Most of us locally have used Carb Connection in Kirkland. Contact info is in the NW section. And yes, you do tuning AFR tuning on the dyno.

Thanks, I'll check it out
"Doing AFR tuning"
Does that mean that they have a Tech to do it who knows what to do?

[Paulporsche]

Gunter,
Speaking from experience I think you're going to like your "new" engine. If you do a dyno run please let us know how you did.

[Superman]

Originally posted by Gunter
Super:
Unless I am mistaken, when the 15% formula is applied, Ralph comes in at 230-35 at the crank.

Is there a dyno in Seattle?

I'm not sure what you are asking. I went with Dane and a few other guys to Kirkland. Torque and HP at the rear wheels turned out to be about 174 on my car, which translates to about 205 at the crank if drive loss is 15%. It's easy for me to remember these events since my car had just a tad more torque than the other cars. One of the other cars was a 3.2 Carrera.

Two side notes: The AFR was perfect on my car. Also, the dyno operator STARED at the torque/hp printout. He said it looked like a classic V8 curve. The credit for that goes to the 20/21 cams.

So, as I say, if someone were to put 98mm P&C's in my car with 9.8:1 CR, I wouldn't be surprised to get 235 hp at the crank.

[Gunter]

Thanks, Super.
Is there/was there a Tech at the Dyno to set/adjust things?

Or do you have the timing and AFR set at another place like JW before you go on the Dyno?

[2002M3Drew]

Originally posted by Carrera3.5L
It seems apparent that you are unsure of different methods of measuring horsepower/torque. Here's some more info for you to ponder...how about PS, DIN, SAE, Kw just for starters...all will give you different numbers with the same engine and we're not even getting started with the type of dyno being used and their variations...

My guess still stands if using a Dynojet (even though I apparently don't know the difference between a Carrera 3.2L & 3.2L SC based motor...

Ralph

A stock 3.2 is a much different animal than a modified, bored-out 3.0 to 3.2 motor. Look at the Porsche 911 Performance Handbook (Anderson) HP charts on modded 3.0s. A bone-stock 81-83 Euro SC put out 204HP, and that wasn't with the non-cat SSIs. With the SSIs, and bored out, that engine should produce 220 at the wheels (at least).

[Jeff Alton]

Time will tell once it hits the dyno!

[dd74]

Originally posted by SC-targa

Remember that Porsche themselve, back in 74 with the 3.0 RS found that an MFI motor with the big overlap "S" cams and the old style tuned exhaust (equivalent to SSI's) needed a 9.8:1 compression to make 230 DIN HP, about 220 SAE net FWHP, I assume local Dynos should be measuring SAE net HP, not DIN.

So they stuck in 10.5:1 and wouldn't you know it? 280 hp.

[boxermania]

If my recollection does not fail me in the racing circles it has been established that one point increase in compression equals a 4% increase in power.

So just to apply the formula if we have a 210 chp engine at 9.5 compression that engine should produce right around 218 chp at 10.5 compression and just to add another twist, if you run a synthetic oil like Redline or Royal Purple you should gain another ~1%.

Just to fatten the pot.........enjoy

[SC-targa]

Originally posted by dd74
So they stuck in 10.5:1 and wouldn't you know it? 280 hp.

Which engine are you talking about?

Yes, when Porsche built the 2.8 liter RSR (race) motors they made 280 HP DIN (~ 265 SAE net) with 10.5:1 pistons. They also used dual ignition, race cams, big ports, race headers and race MFI. What's your point?

The 3.0 RSR was a initially a disappointment because it couldn't make the usual 110 HP DIN per liter that the smaller GT racing engines had all made. The factory RSR's had to run throttle slides in their MFI as opposed to regular throttle flap valves to hit the required 330 DIN HP (roughly 315 SAE net HP)

My question is, do you think that a CIS motor with a CIS cam can meet or exceed the power output of that an MFI motor with a very hot, high lift, high overlap, long duration cam produces? I don't believe so.

I really believe that Gunter is going to have a terrific motor that will make more power than a stock Carrera 3.2. I also believe that many people muddy the waters when they discuss engine power because they don't understand the differences between the different rating systems (or maybe they do) and many folks sling around big numbers for HP that just don't sound realistic.

Maybe John or Grady or Steve W will chime in here with an opinion.

To each his own,

Jerry Kroeger

[dd74]

Originally posted by SC-targa
Which engine are you talking about?

Yes, when Porsche built the 2.8 liter RSR (race) motors they made 280 HP DIN (~ 265 SAE net) with 10.5:1 pistons. They also used dual ignition, race cams, big ports, race headers and race MFI. What's your point?

The 3.0 RSR was a initially a disappointment because it couldn't make the usual 110 HP DIN per liter that the smaller GT racing engines had all made. The factory RSR's had to run throttle slides in their MFI as opposed to regular throttle flap valves to hit the required 330 DIN HP (roughly 315 SAE net HP)

My question is, do you think that a CIS motor with a CIS cam can meet or exceed the power output of that an MFI motor with a very hot, high lift, high overlap, long duration cam produces? I don't believe so.

I really believe that Gunter is going to have a terrific motor that will make more power than a stock Carrera 3.2. I also believe that many people muddy the waters when they discuss engine power because they don't understand the differences between the different rating systems (or maybe they do) and many folks sling around big numbers for HP that just don't sound realistic.

Maybe John or Grady or Steve W will chime in here with an opinion.

To each his own,

Jerry Kroeger

My point is if you raise compression and exorcise breathing restrictions, many more possibilities open themselves up for an engine. A deep-breathing 2.8 will give a 3.8 a run for its money, IMO.

Sure, with the mentioned modifications, Gunther will have some hp. But to get the unmitigated hp these engines are capable of - 300 hp and above for the 3.0 - CIS won't get one there. The correct way to do things requires a full engine tear down, new P/Cs, cams and induction, so arguing the contrary (other than turbo charging the motor - which still could require a tear down) is a moot point.

That's not to say CIS isn't bad. It's really rather good in the real world sense.

[Carrera3.5L]

Originally posted by 2002M3Drew
A stock 3.2 is a much different animal than a modified, bored-out 3.0 to 3.2 motor. Look at the Porsche 911 Performance Handbook (Anderson) HP charts on modded 3.0s. A bone-stock 81-83 Euro SC put out 204HP, and that wasn't with the non-cat SSIs. With the SSIs, and bored out, that engine should produce 220 at the wheels (at least).

I apparently haven't read as many books as you (and I certainly don't believe everything I read as I've often witnessed the opposite) so I guess I'll agree to disagree, but I have seen/built/driven many of these same engines and on the dyno these popular and smoggable 3.2L CIS spec engines didn't make 220+ at the wheels (Andial used engine dynos because chassis dynos didn't exist back than but I'll even assume 15% driveline loss for argument sake and convert back to whp). I've also been fortunate to have driven many of these combos in the cars in those years, from 3.2L conversions just like Gunters all the way to a 3.0L>3.6L CIS w/ 964 cams that was done in 1990 when the 76.4mm crank first became available.

At least Jerry Kroeger and a couple of others appear sane and have a voice of reason...

Gunter, many chassis dyno operators charge extra for a/f monitoring and graph (some don't) but many also won't touch your car for liability reasons unless you specifically hire them to do so. If you envision yourself tweaking while strapped down on the dyno, I would suggest getting a flat rate so you can do multiple pulls as needed rather than paying for 2 or 3 pulls and than having to pay again if you're not happy with the results and want to tinker. Depending on the dyno operator, some are willing to work with you on price and some aren't.

My comments (whether in this post or in previous ones) also shouldn't be taken as a slight against you or against your motor, I hope that you find the horsepower you are seeking and expecting, it's just my experience (and take that with a grain of salt if you wish) I don't see 220+ at the wheels with a small displacement increase, "normal" CR, CIS and a mild camshaft profile...I can say that it will make a significant difference over what you have now and hopefully you will be happy with the end result.

200 SAE at the wheels on a Dynojet (or approx. 235 crank for those dyno or mathmatically challenged) with a nice flat torque curve is realistic and something I'm sure you would be pleased with.

Ralph

[Gunter]

Originally posted by Carrera3.5L

200 SAE at the wheels on a Dynojet (or approx. 235 crank for those dyno or mathmatically challenged) with a nice flat torque curve is realistic and something I'm sure you would be pleased with.
Ralph

Ralph, your reply and some other ones, sound realistic to me.
I'll check out the Dyno in Kirkland, WA.
About 235 at the crank was my intend before the rebuild.
I tried to keep it within reason, no carbs, or twin-plugs, or MSD, or EFI, just mildly agressive street driving.
By using a larger CIS on top of 98mm P/C's with 9.8:1 CR and the SSI's, I figured on adding about 40-50 horses to the stock 180.
I felt that the extra ~50 horses would make an SC really fun to drive without stressing the 915 too much. (It has LSD and was just rebuilt by JW in Seattle)

Yes, I could have gained more by doing other things but, before going overboard with a 3.0 liter, I would get a 964, or a 993 with a 3.6, coil-overs, G-50 transmission, etc. and do some mods there.