1985 3.4 build using MAF 279.56 HP, 237.63 RWHP

[85MytFast]

KTL thanks for the comments. I may move to a dc40 or a dc43 over the winter. I didn't want it to sound rough so I was a little more conservative than Terry thought I would like. I am sure I could have handled 11:1 compression pretty easily too.

I liked the JE pistons over the Mahle because of the design with the twin plug, plus the ability to go hotter on the cam. I did use new Mahle 3.4 cylinders though.

Berk I can get to 93 octane here by spiking with a little 100 proof. I used to try and run that when it was a Euro configuration because of the single plug and 10.3 compression. It is nice being able to run with pump gas that is widely available. I just try and make sure it isn't an ethanol blend so it doesn't affect power.

[KTL]

Rick,

I had S cams (WebCam's 149S grind) which is sort of similar to DC40, often referred to as Mod-S on my 3.2 carbed engine and it sounded pretty lumpy. https://www.youtube.com/watch?v=_a8pdgpaWec Its the #45 car at the very start of the video. Sounded pretty raucous due to the straight pipe exhaust with dual pipes and no mufflers.

If you like the sound of that, you'll like the sound & performance of the DC40 This fella's 3.0 rebuild with Weber carbs and a Bursch stinger exhaust used DC40 cams. https://www.youtube.com/watch?v=XoPsMaWw_LE Good midrange and higher rpms power. Bottom end is a bit soft.

By the way, where did you source the Andial ignition signal splitter?

[85MytFast]

KTL your car certainly is louder than mine! Sounds fun! I remember being 16 and shutting my car off about a block from home and coasting to kill the rumble, didn't want to wake my parents at that late (actually early) hour. Terry (engine builder) has DC40s on his early 70s car. It is pretty fun to drive too. I like the low end torque I am getting now, and the red line is currently at about 7200 for longevity.....sounds like a conversation with John Dougherty is in order. For now I am just going to enjoy it until winter.

Terry was able to get me the splitter, it was new too. I think they are a little tough to find. I liked this method because it was simple for me to understand and old school. I also was trying to keep it mostly "original" in appearance. You might shoot him a pm.

[KTL]

It's crazy loud. Here's what it sounds like on decel from high rpm. Sounds awful.

https://vimeo.com/groups/63643/videos/14950324#t=137s

I've since switched to a merged outlet pipe setup which sounds higher pitched and a lot "cleaner" due to the mixing effect.

Thanks for the tip on the ignition splitter. I agree its a great way to go to retain the factory style l ignition electronics & ECU. Finding a twin plug distributor is not a big deal either. They seem to be readily available.

[911 tweaks]

how has this build held up...? granted it has only been a few months...
great info... thx for sharing...

[85MytFast]

911 Tweaks I have driven a couple thousand miles since the build, it still runs quite strong. Very happy at this point. I am planning on putting in a hotter cam this fall. Going with a DC43-110. Since it is just for fun a little more sound doesn't bother me! It currently is quieter than I anticipated.

Thanks for your interest,
Rick

[911 tweaks]

thx rick that is good news...
when you say the cam going to is DC43-110...does the 110 number signify the degree opening btwn the lobes...?? if so, I am very interested in how this will work out as i have a build project that requires a lumpy aka muscle car type of idle... will this cam make your engine idle lumpy = blat, spat, burp, pop, omph, spat, ect...?? thx, bob

[85MytFast]

The 110 number is the lobe separation. It is quite smooth now so a little lumpy sound I think I will enjoy. It will be a couple months before that is finished.

Rick

[911 tweaks]

thx rick... something in my memory tells me that the 110 seperation is the max for some carb set ups due to reverberation or is it some f/i set ups...?
either way, do you know what degree of seperation is needed to have the real lumpy engine idle...? ( i understand that if this very lumpy engine idle sound is sought after, many other engine build parameters need to be closely monitored a/o designed into the build)...
lastly, please post your new cam info either on this thread or post a link so i dont miss how it goes for you... thx again...bob

[85MytFast]

Will do Bob. We are doing a little more research to make sure that is the cam I want with this separation. It sounds like the MAF should allow a little lower separation number than the old AFM.

The degrees of lobe separation and lumpy sound stuff is too deep into the weeds for me to comment, I have to rely on Terry and Sal and the cam guys for their expertise on that. My current cam sounds and runs pretty smooth to me though, so I have some room to work with.

I will post what we decide on and the results.

Rick

[scarceller]

The overlap is what causes lumpy idle not necessarily the 110 lobe center line. The DC43-110 has more overlap but is far from a radical cam, it has about 43 degrees of overlap (valve seat to seat) compare that to the stock 3.2 cam at 37deg and the stock 964 cam at 45deg. So it actually has less overlap than the stock 964 cams do but far more duration and lift. The 43deg number is from the time the intake valve just lifts off the seat to when the exhaust closes back onto the seat, this is know as overlap at 0" lift. The DC43-110 cam will likely idle just fine.

Originally Posted by 911 tweaks

thx rick that is good news...
when you say the cam going to is DC43-110...does the 110 number signify the degree opening btwn the lobes...?? if so, I am very interested in how this will work out as i have a build project that requires a lumpy aka muscle car type of idle... will this cam make your engine idle lumpy = blat, spat, burp, pop, omph, spat, ect...?? thx, bob

[Mick_D]

I wonder how this turned out with the new cam? I really like the sound of the praise for this build. Wonder what kind of ballpark dollars we're talking?

[scarceller]

For dollar amount on a build like this contact Terry Worick he built this motor
Terry Worick
I did the EFI setup.

We are still working on best cam choice, we do not yet have the final combo for this engine. But it won't be the DC41-110 cam. The motor has had 3 cams and even 11.5:1 comp pistons, we are still working on the best combo. We'll post final results once done.

[Tom_in_NH]

I'm confused where you're getting the 279 hp from. That DynoJet graph reports ~238 hp (still a pretty healthy number). The DynoJet dynamometer tq and power calculations attempt (cough) to report flywheel power.......so they're already reporting 15-20% higher than virtually every other chassis dynamometer by doing this. Virtually all other chassis dynamometers report wheel power....not flywheel power.
The fudge factor that DynoJet came up with was based on the testing they did on their first dynamometer, which came up reporting 90 hp for a 140 hp Yamaha V-Max bike.
The full story is here:
The Story Behind the Dynojet Chassis Dyno - The Truth Meter - Hot Rod Network

[scarceller]

We ran this setup on both a Mustang dyno and a dynojet we did these a few days apart, nothing changed between the runs and weather conditions about the same. The dynojet gave us 238WHP while the Mustang came in at 232WHP. THe dynojet calculates HP at the wheels, basically it figures this out from the acceleration rate of the drum. It could be that years ago dynojet did things different but the modern dynojet measures WHP.

The dynojet does favor low HP engines simply because they can't accelerate the 3500lb drum very quickly. A pull from 2000-7000RPMs takes about 20seconds on a dynojet with a 911 motor putting out 230WHP. That's an average acceleration rate of about 5000/20=250RPMs per second, extremely low accel rate and not real world. On the street that same car in 2nd gear will rip through 2000-7000RPMs in less than 4 seconds! Street conditions have acel rates of 800-1500RPMs per second not 250rpms/sec! An engine accelerating at 1000RPMs/sec will NOT put down as much HP to the ground as the same motor at a rate of 250/sec, simply because huge amount of HP is needed to keep up the acceleration rate. This is why the dynojet is a cheater dyno, it does not lie it simply calculates torque/HP based off accel rate but that rate is not realistic!

Now the Mustang dyno: totally different beast and in the correct hands it can match the exact conditions of the dynojet but you need to know howto use it. On the Mustang you can specify the acel rate you'd like to hit, so if you know what it was for the dynojet you just enter that acel rate of 250RPM/sec into the Mustang and you'll get fairly close numbers. However, most Mustang dyno operators don't do this they use a mode that simply mimics street driving and the rate is then set much higher 700-1000RPM/sec. You lose a lot of power at the ground/wheels with acel rates that high. I have actually done test on the Mustang at the extremes, for example setup a run at 1000RPM/sec and make note of peak HP and at what RPM it occurs, usually around 6200RPMs in the 3.2L then setup another run in lock and hold mode at 62000RPMs, this mode tells the Mustang dyno to simply hold at 6200RPMs, effectively at an acel rate of 0RPMs/Sec. In a lock and hold strategy nothing is being lost to acel rate because you have a rate of 0! You need to think about this for a bit before it makes sense. The diffidence in HP at 6200RPMs between those 2 test cases will differ by as much as 10%! Again the dyno is telling the truth in both cases, but at the wheels those 2 cases are very different.

What I just explained also applies to engine dynos but to a lesser degree since the rotating mass is far less without the transmission and wheels but it still applies because the motor internally also has mass of the crank, flywheel, pistons, valves, cams, ...

Bottom line is that the dynojet has no knobs to turn to control acel rates, it simply is what it is but it favors little motors (less than 300WHP) simply because they can't spin the drum up quickly and this favors the numbers because you have less losses per unit of time and more created torque makes it to the road.

The Mustang and other load dynos are very different and in the proper hands can do exactly what the dynojet does and so much more.

Folks get way to hung up on the numbers, they really don't matter much other than to compare from one run to the next after you make changes. The best indicator of performance is 0-60 times or accelerometers that can show rate of acceleration from real street runs for a given setup on the street.

With all that said the dyno-jet is still a very good predictable dyno to compare runs from different dynos and engines simply because it has few knobs to tinker with. Only problem is that a acel rate of 250rpm/sec is far from real world street run.

Hope that helps a bit.

Originally Posted by Tom_in_NH

I'm confused where you're getting the 279 hp from. That DynoJet graph reports ~238 hp (still a pretty healthy number). The DynoJet dynamometer tq and power calculations attempt (cough) to report flywheel power.......so they're already reporting 15-20% higher than virtually every other chassis dynamometer by doing this. Virtually all other chassis dynamometers report wheel power....not flywheel power.
The fudge factor that DynoJet came up with was based on the testing they did on their first dynamometer, which came up reporting 90 hp for a 140 hp Yamaha V-Max bike.
The full story is here:
The Story Behind the Dynojet Chassis Dyno - The Truth Meter - Hot Rod Network

[panzerfaust]

sal

well said... in a nut shell dynojets are an inertia based and a mustang is load bearing type. not that a dynojet totally useless for tuning or measuring but load bearing dynos are much more useful since the loads are closer to what a drivetrain does on the actual road.

i chuckle when the internet says dynojets are t"the gold standard" dynojets do make load bearing types also now but they are much more expensive so shops mostly have the inertia type.

[gliding_serpent]

Dynojets are the gold standard for comparing and bragging rights because they are more standardized. Load bearing dynos have more options for tuning. But those options reduce standardization, making it harder to compare my dyno numbers to an identical build elsewhere.

As my mustang operator said, "i can make it look like your car has 1000hp" but compared to his old dynojet that was right next to his mustang... They way he ran it, the mustang have ~8% lower numbers. But he got rid of the dynojet because he was a tuner... And the mustang was far superior for that given his needs.

[aircooledfan911]

Hey everyone.
First post here on PP. I bought this car from a local St. Louis dealer last year. It is an amazingly fun car to drive. Kudos to the OP as well as the restoration team with Terry Worick for an amazing job on this car.

[scarceller]

You bought a fantastic build! Enjoy!

[aircooledfan911]

Originally Posted by scarceller

You bought a fantastic build! Enjoy!

As the dealer had very limited paperwork with the car, just the books and reprints of pics from the op and terry’s website, i’d appreciate if anyone familiar with the final build could update me about it’s final configuration.

That said, it is a joy to drive. It accelerates like a bat out of the netherworld. The clutch took some getting used to. Switching to turbo tie rods made the handling a little more precise. It still sounds amazing.