565 cubic inch BBC build

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
To begin with it is a given that my choice in cylinder heads for this 565 was a dead miss. I wanted to keep the Dart 4500 oval intake from my 500 incher to use with these 300's.
http://www.airflowresearch.com/index.php?cPath=68_129
This build was more than a headache for me and took a while and some tweaking and remachining to get here.
Mike, to be clear, these are heads which Tony Mamo ported and are not typical 300cc production pieces. The production heads don't flow 405 cfm on the intake nor do they flow 325 on the exhaust side which is a near 80% IE ratio. There were several things I wasn't happy with the first go round so I made a piston and ring change and a slight cam change which more suited the 80% IE ratio. Tony and I decided to go to near straight up on the intake/exhaust lobe as these heads son't require the split of a larger cc intake port.
Compression remains at 14 to 1. This cam is .779/.750 280/282 on a 112 spread using a 1.75 int and a 1.7 exh ratio respectively.
So again, these heads were not the correct choice for this displacment but sometimes a little head can go a long way.
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Once committed there wasn't any turning around because the money had been spent so with Tony's help on the cam spec's the project moved forward with some serious speed bumps in the machine shop area as many of you already know. My brain fart didn't help when I degreed the cam 4* retarded from where it should have been. I still don't know how I missed it but I did so I own it.
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So with the undersized cylinder head we still managed to produce a satifactory result given my goals. It is a given that with a larger cc intake runner such as the mamo 360 piece the results would be much better than they are. It's also a given that with an electric water pump and a "race style" oil pan along with a more efgficient vacuum pump the existing combo would have produced a few more ponies than it did but these are the results with no more than a valve adjustment, the swapping of distributors due to errant timing and a couple timing changes where we found that there was no power difference between 30 and 35* timing.
Dart Big Block Chevy Big M Engine Block


Tech Tip - Oiling System

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Tony Mamo;8251034 said:
Guys,

Thought I would chime in quickly.

This engine has been a long journey for Dan.....after initially testing some six months ago with "OK" results, it was evident the torque was lower than it should have been even though the power at 850 HP or so was inline with what you might expect from such a small head. The motor simply carried better than you might expect so the power was there in spite of the torque being down quite a bit (I told Dan it looked like the curve of a good 520 inch engine....LOL).

Also....I told Dan time and time again (he will vouch....LOL) I never expected much more than 850 - 875 HP from these heads (still a significant number really) but we all suspected that there may be potential issues with the shortblock (it was obvious something was amiss with the lower TQ #'s) and after sleeping on it awhile Dan decided to tear back into the engine and see what's what, which clearly turned out to be a great move. I wont go into all the details but after swapping pistons and us running an even smaller cam than the previous grind (less exhaust lobe which I felt would help the TQ some and we didn't need to crutch the exhaust that much with an 80+ % Exh to Int ratio), the power curve of the new motor is off the hook. The thing that looks different to me due to the smaller head moving air at a higher rate of speed earlier in the curve is the lead in TQ.....its close to peak a thousand RPM's before it gets there and carries extremely flat and extremely well helping to finally net the 900 ponies Dan ultimately achieves.

I have seen higher peak TQ figures from high compression 565's (from the additional airflow of a larger head) but what surprised me is how well this engine carried the torque it made.....it just goes against conventional wisdom somewhat with the head being obviously far from ideally sized for this combination

My hat is off to Dan.....I couldn't be happier for him as he really went the extra distance in an effort to make things right and I'm glad it paid off for him and he got the number I doubted was achievable with this combination (the "900 " figure), and whats funny is there is more lurking here with some of the other items mentioned (a better kick out pan versus more of a street pan for windage control, EWP to free up a few ponies on the dyno etc.).

For those who prefer to look left to right to appreciate the sexy curve of this engine here you go!



Regards,
Tony

PS....Wanted to mention the manifold on this engine which was/is a critical component to the final results, was ported by the late Roger Helgesen not long before he got too sick to do any more porting work. I kind of felt his presence in the dyno cell yesterday as I looked at the intake manifold and big Dominator carb cooling off after the pulls we made still somewhat surprised by the end results. If there is an afterlife he was certainly smiling as well.....Roger and Dan were good friends btw and everything worked out in such a fitting way.
Its pretty much 900 HP from 6700 - 7100! :thumbsup:

Like I said, very surprising how well it hangs on and the big power is in early and carries beautifully (no fast roll over here).

Didn't touch the openings at all.....its the exact same size as the OEM CNC program I designed for AFR.....most of the work is in the bowls, chamber, and valvejob as well as the cuts on the valves themselves

The later model "roval" design has a much better cross sectional area (and shape) than the original oval port design from the 60's and 70's and is the main reason I went with it in spite of the limited manifold availability in out of the box as cast pieces (most have the old shape).....I just felt the newer design lent itself to much better performance and there is no better proof of that than this particular engine which is likely the highest output N/A I have ever seen recorded in the oval port line-up

This engine is going to be absolutely wicked in the car.....it will take throttle nobody's business and I'm quite confident the power and brutal responsiveness is going to scare the **** out of Dan for a good while.....LOL

I have helped numerous customers with reworked 265's, 290's, and 300's and they ALL comment on that same scenario I just highlighted. One guy lost a rod bearing cause he cant help himself and always shows off at the car shows by zinging the engine in neutral....he says it revs so quickly it sounds like a flat plane crank Ferrari engine.....LOL

What I encouraged Dan to do at the time (when he still had a choice about which head to have me involved with), was to run a larger head better suited to the displacement of his engine. However he really wanted to retain his intake manifold (the ported Dart) and for whatever reason was really excited about the prospects of a reworked 300 in conjunction with the 565 CID displacement.

While I thought I would be a really unique build and was curious about the prospects, I was also convinced it would be limiting his power potential with the small head (which I know was good advice), however Dan was convinced it could make 900 HP and I just kept telling him that even a reworked 300 isn't the right choice with that goal in mind.

While I stand by my advice on that, the best part is he nailed his goal in the end and I couldn't be happier for him. Also, once we were committed to moving forward with the 300 cc head, I was always excited about the prospects of the build as well having always enjoyed doing more with less (being competitive with cars alot heavier than the competition.....things like that).

For the record, I never said 900 was out of the question, just told Dan it was more of a best case scenario and I prefer to prep my clients to expect a number that might fall more in the middle of the range. When the topic came up (and it did often), I always told Dan to look for 850-875....and that anything more is gravy. Truthfully going into "round two" with the new pistons and different cam etc, having seen 850 ish with round one, I would have been thrilled to see 880 knowing the significance of that number on a dyno I know to be accurate (I struggled to make 650 HP with an LS build I dyno'ed a few weeks prior on the same dyno.....apples and oranges but my point is you have to earn it over there).

Could he have easily made 975 with the exact same shortblock and my new MMS 360 rect port heads.....without a doubt. Is it as cool and unique as making 900 with roval port 300 heads??....probably not.....LOL

And once again, this will be a very unique sounding engine in the car.....I'm looking forward to some in car videos of this combination.....Dan if you don't have a Go Pro and a mount in the car somewhere to attach it to, put it on your Xmas list!!
-Tony

http://www.superchevy.com/how-to/project-cars/sucp-1208-big-block-heads-shootout-the-o-vs-r/

http://garage.grumpysperformance.co...u-thinking-about-your-potential-combos.14607/

http://www.airflowresearch.com/index.php?cPath=68_70
 
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