The Mighty 3.0 MFI Motor Has Finally Had It

[Jeff Higgins]

I actually broke the last version in on a chassis dyno. Did about ten pulls, gradually increasing throttle and rpm. It put down about 215 hp at 6,200 rpm and 208 ft lbs of torque at 5,000 rpm. So, using the standard 15% drivetrain loss, about 247 hp and 239 ft lbs. Not hugely impressive numbers for a hot rod 3.0, but very satisfying for a street motor. I willingly gave up peak numbers for flexibility and drivability.

I started with an '83 SC motor, so a "small port" 3.0. I did this so I could port match the intakes to the throttle bodies, and I wanted to use 36mm throttles from a 2.4 S or 2.7 RS. I opened the intake ports to 38mm ("big ports" are 39mm), leaving a 1mm "reversion ledge" between the ports and throttle bodies.

John Dougherty and I worked out the cam profile for this motor over the course of many phone calls. I had my own ideas, and he helped me refine them. The grind we settled on is his GT2 turbo grind, but with the lobe centers narrowed to 102 degrees from its standard 112 degrees. The result is a very high lift, short duration cam. It has enough valve opening to feed 3.0 liters of displacement without resorting to very narrow lobe centers, high overlap, and long duration that would provide very high rpm power. I wanted mid range grunt, not peak power. The other big plus is that these cams work with stock springs due to their gentle ramp angles. I didn't want to introduce stresses into the valvetrain by running heavy race valve springs.

So, in the end, a street performance motor, not a race motor. The throttle response is amazing, it revs willingly to 7,000 rpm, providing a bit of over rev if I really need to get to that next corner, and its longevity was just proven. I'm looking forward to another 100,000+ miles on this version. That should get me over the finish line.

[stownsen914]

Very quick turn-around time, Jeff. Sounds like you should be set for another long run with your new motor.

Re: knock sensing, there is an option for our analog motors called KnockLink. Neil Harvey mentioned it here on the forum a while back. It's basically a knock sensor with a warning light to put in your dash.

[daepp]

I can’t believe how fast you turned that motor around - bravo!

[icarp]

Thanks for the data on the 3.0 Jeff

Enjoy the next 100,000 miles !

Ian

[Jeff Higgins]

I've been having a conversation off-line with a local enthusiast regarding an ignition "safety" system that operates on a knock sensor, one that actually cuts or retards ignition to those cylinders that are knocking. Very intriguing. I'm going to go ahead and get in touch with the company that manufactures this system and see what he has to say. J&S Safeguard is the company, they have been discussed here in the past.

I'm a little bit concerned that my archaic Electromotive HPV-1 system may not be adaptable to this. I know there are a lot of mixed opinions regarding this system, but I think my real world experiences with it pretty much put paid to the naysayers. This system has been on this motor from day one, so it has now covered over 125,000 miles, those 80+ track days, and all of that. Absolutely no issues of any kind, ever. Very easy to work with and adjust timing as well as a built in "soft" rev limiter. I really like it, and would be reluctant to give it up.

That aside, the new build now has about 500 miles on it. I showed up last Sunday for our local PacWest R Gruppe chapter's "last Sunday" drive, with several members already milling about the parking lot. They all know this car very, very well, having followed me around, some of them anyway, for some 20-odd years. They all asked me what was "different", because it was so much quieter and not nearly as "stinky" (another MFI "feature"...). I've noticed these changes as well, but thought it was just me. By the end of our drive, they all said that, no, it's not you, we can all hear and (not) smell it. I literally put the same induction, in the same state, right back on it, along with the exhaust. The only change in specification was the reduction in compression ratio. Weird...

Oh, and as far as the quick turn around, I do have pretty much unlimited time to devote to such things. I've been retired for seven years. And, well, as other retirees will tell us, sometimes we get a little bored, yearning for "something to do". So, given something to do, I attack them with gusto. Now, alas, I'm bored again... guess I'll have to go for a drive or something...

[al lkosmal]

Jeff,
The HPV-1 is basically a wasted spark, dumb coil system. Simple and effective system. Per their website the J&S Safeguard "Vampire" works with wasted spark, dumb coil configurations. ....interesting. Let us know what you find out.

al

PS: "smart coils" typically are 3-wire coils, Coil-on-plug (COPs), with an internal ignitor built into the module that is triggered by a low voltage signal..."dumb" coils are 2-wire with no built-in ignitor.

[Jonny042]

Originally Posted by Jeff Higgins

That aside, the new build now has about 500 miles on it. I showed up last Sunday for our local PacWest R Gruppe chapter's "last Sunday" drive, with several members already milling about the parking lot. They all know this car very, very well, having followed me around, some of them anyway, for some 20-odd years. They all asked me what was "different", because it was so much quieter and not nearly as "stinky" (another MFI "feature"...). I've noticed these changes as well, but thought it was just me. By the end of our drive, they all said that, no, it's not you, we can all hear and (not) smell it. I literally put the same induction, in the same state, right back on it, along with the exhaust. The only change in specification was the reduction in compression ratio. Weird...

With 100k on it your motor must have been been pretty beat, and your new compression probably only lost you a few percent of power - maybe just being fresh its making more power, running cleaner, leaner, and cooler and less smelly?

Great to hear it's running in nicely. Get out and drive!

[rswannabe]

Jeff, I installed J&S Vampire knock sensing in the 3.6 in my ‘74 and am very happy with it. Let me know if you want to check it out in operation. John, the owner of J&S was great to work with and very helpful. Give him a call direct.

[Jeff Higgins]

Originally Posted by rswannabe

Jeff, I installed J&S Vampire knock sensing in the 3.6 in my ‘74 and am very happy with it. Let me know if you want to check it out in operation. John, the owner of J&S was great to work with and very helpful. Give him a call direct.

Thanks, Brooke, I'll have to take a look at your setup. And yes, the Vampire appears to be the one.

As an interesting aside for the rest of you, I bought my Electromotive system from Brooke some, what? fifteen, sixteen, seventeen years ago? Where does the time go...?

[Jeff Higgins]

Originally Posted by Jonny042

With 100k on it your motor must have been been pretty beat, and your new compression probably only lost you a few percent of power - maybe just being fresh its making more power, running cleaner, leaner, and cooler and less smelly?

Great to hear it's running in nicely. Get out and drive!

Yeah, in retrospect, I should have freshened it up many miles ago. It was, until the end, still running fantastic, using very little oil, getting decent (for MFI) mileage, etc. No indication that it was "tired", so I kept on keepin' on.

I think I learned where the limits are, though. 3.0's have the reputation as one of, if not the most "durable" of the air cooled family of motors. I think I always had that notion in the back of my mind, driving a false hope of getting many more miles on it before a rebuild. But, well, I hammered this poor thing a lot harder than most. It was, essentially, driven like a "race" motor over the course of those 80+ track days.

My friends who do actually race similar motors in vintage competition rebuild at 30 hours. They were astonished to learn just how far I had pushed mine. One of them sometimes does our track days in his '70 911 race car, and he told me that when following me that "um, no... you run that thing as hard as any "race" motor. don't kid yourself".

So, yeah, it was time. Looking forward to many more miles with my refreshed motor. I will definitely at least take a look at things much sooner this time.

[Jeff Higgins]

Here is one that has me baffled - I have been averaging about 12 mpg while breaking in my refreshed motor. While MFI has never been known for getting any kind of decent mileage, the old motor averaged about 15-16 mpg in just general driving, and would touch 19-20 mpg at a steady state speed limit-ish freeway cruise.

Now that it's thoroughly broken in, it looks like it's time to break out the old LM-1 and run my old test loop. Interestingly, everyone who knows this car that has been around it post rebuild has commented on how much "cleaner" it appears to run. My suspicion is, of course, that it must be running quite rich, but the LM-1 will be the ultimate judge of that. If that is the case, though, it should be "stinkier", not "cleaner".

Ah, but the vagaries of internal engine workings. I changed literally nothing other than lowering compression. The same induction went right back on the motor exactly as it was removed, as is the case with the exhaust. Same cams, same heads (albeit rebuilt), same ignition, same everything.

I have a hard time trying to imagine how the reduction in compression ratio could have had this affect. There has to be something going on in either the intake or exhaust flow (or both). Could it be simply because the piston dome doesn't go as high up into the combustion chamber as it used to? A little better flow across its dome during the overlapping phase of valve actuation, since both valves can "see" each other better? A little more room around each valve when they are open?

Any increase in airflow, however, should result in a leaner mixture and therefor better mileage with an MFI system. Hmm... "things that make you go 'hmm'...".

[daepp]

Just by way of another data point, your city and highway mpg mirrors my 72 with MFI, "E" cams and 9:1.

Good luck!

[Jonny042]

Originally Posted by Jeff Higgins

Here is one that has me baffled - I have been averaging about 12 mpg while breaking in my refreshed motor. While MFI has never been known for getting any kind of decent mileage, the old motor averaged about 15-16 mpg in just general driving, and would touch 19-20 mpg at a steady state speed limit-ish freeway cruise.

Now that it's thoroughly broken in, it looks like it's time to break out the old LM-1 and run my old test loop. Interestingly, everyone who knows this car that has been around it post rebuild has commented on how much "cleaner" it appears to run. My suspicion is, of course, that it must be running quite rich, but the LM-1 will be the ultimate judge of that. If that is the case, though, it should be "stinkier", not "cleaner".

Ah, but the vagaries of internal engine workings. I changed literally nothing other than lowering compression. The same induction went right back on the motor exactly as it was removed, as is the case with the exhaust. Same cams, same heads (albeit rebuilt), same ignition, same everything.

I have a hard time trying to imagine how the reduction in compression ratio could have had this affect. There has to be something going on in either the intake or exhaust flow (or both). Could it be simply because the piston dome doesn't go as high up into the combustion chamber as it used to? A little better flow across its dome during the overlapping phase of valve actuation, since both valves can "see" each other better? A little more room around each valve when they are open?

Any increase in airflow, however, should result in a leaner mixture and therefor better mileage with an MFI system. Hmm... "things that make you go 'hmm'...".

Is there a chance you are enjoying it more? It could be your right foot...

[Jeff Higgins]

Originally Posted by Jonny042

Is there a chance you are enjoying it more? It could be your right foot...

There is that... I have achieved a low of 9 mpg on many track days. These things sure dump in the fuel when they are playing. And, well, me and The Little Blue Car (as it's known locally), have been playing...

[Rosco_NZ]

Interested to know where the AFR’s were after rebuild …