Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?

[Walt Fricke]

I ended up with a motor Grady Clay originally built for a racer. 66mm crank x 88mm jugs. They were an EMPI import from Japan, I believe. Iron cylinders. Short stroke 2.5. S cams. Small twin plug heads (2.0, but not the '69s). Raced it for a year, ran great. Sand cast case became a donor when another motor blew up. If there were head temperature issues (or any temperature issues anywhere), they were not evident in one season of use, and everything looked OK when torn apart. Rods and crank reused in a 2.3 race motor (66x85). Other bits gathering dust.

A 2808ml motor might produce more thermal stress? Maybe not.

[tscrihfield]

Andrew,
Yes the engine is very healthy and was all built in his garage, minus machine work.

If I could make some recommendation, the best possible solution to ensure good fuel is to tear that POS crossbar that link the carbs and either find a source or build your own bell crank style system. Those crossbars are difficult to sync and hard to keep sync'd. My other recommendation is to run EGT sensors(even if they don't stay on all of the time) for carb syncing. many will say that vacuum is the way to go, but exhaust temps will not lie to you. Other than that drive it like you stole it, these cars were made to enjoy!

Thomas

[Henry Schmidt]

Originally Posted by Walt Fricke

I ended up with a motor Grady Clay originally built for a racer. 66mm crank x 88mm jugs. They were an EMPI import from Japan, I believe. Iron cylinders. Short stroke 2.5. S cams. Small twin plug heads (2.0, but not the '69s). Raced it for a year, ran great. Sand cast case became a donor when another motor blew up. If there were head temperature issues (or any temperature issues anywhere), they were not evident in one season of use, and everything looked OK when torn apart. Rods and crank reused in a 2.3 race motor (66x85). Other bits gathering dust.

A 2808ml motor might produce more thermal stress? Maybe not.

The EMPI 88 were Biral barrels. Cast iron liners with aluminum fins. Aluminum fins being the key word here. Even the low quality aftermarket EMPI cylinder was designed to employ the heat dissipation properties of aluminum in an air cooled engine.
One quick question Walt: what type of fuel did you run in your 2.5?

[Lapkritis]

Henry - not to go backwards on a topic but have you ever run an engine that is out of OE spec for piston clearance on the loose end of bore in cast iron? I have, and currently do (not this engine) with an unnoticeable result. The engine produces serious HP with forced induction and consumes only a half quart more oil than a stock engine between changes. Rev is smooth and fast.

Ring gap (cheap rings, Grant brand) is also loose as the engine is due for an over bore by all measures except performance and reliability... which are the most important measures of all in my humble opinion.

Curious what your experience has been: Worn bore, fresh ball hone, new rings, rigorous break-in procedure, cast iron cylinder, synthetic oil after break-in, turbocharged over 20lbs manifold pressure or not if no turbo charged experience on such a creature.

Baseline street tune, ignition yet un-tuned for MBT:





Bore worn loose post-hone:

[Henry Schmidt]

Originally Posted by tscrihfield

Nice build!

My personal take on the iron cylinders. They'll be fine. I have a good friend running a twin plug 2.5 long stroke small bore engine that dyno'd at 265hp @ 6xxx rpm. I've watched it run three maybe four seasons without rebuild and he runs 10-12 weekends a year.

I bought a 74 2.7 and plan to build it in the next year or so... Keep us up to date how the cylinders hold up. I may have missed it mentioned, but what pistons are you running?

Thomas

Taking into consideration that the factory ST 2.5 long stroke (70.4 X 87.6) made 270 with racing high butterfly MFI injection @ 8000 your friends engine defies reason. Where was the magic?

Without being too confrontational, I would be willing to bet money that the 265 hp 2.5 does not have cast iron cylinders. Perhaps Birals

BTW: 4 years , 12 club races a year times, 3 hours a weekend is less than 15K miles. 15K on a race engine that spins less than 7K should last a very long time.
Most racing 2.5 are built to turn 8K.

[Lapkritis]

Depends too much on the type of dyno and correction factors to know you're comparing apples to apples.

[Geneulm]

2.5+6k+nitrous=265?

[tscrihfield]

Andrew,
I am very interested in talking more about where you go with this engine. I will continue to watch your progress! Innovation often has costed many but many have discovered great things while making errors... Plus there are a multitude of folks running iron otherwise they would have stopped producing them years ago.

Thomas

[Henry Schmidt]

Originally Posted by tscrihfield

Henry,
I'm not getting into your dick measuring contest. You're not worth my time and I don't appreciate your pity arrogance when you have limited to no knowledge of what someone is saying. I'm sure that for someone that has no engine knowledge you seem very intelligent and I'm sure you build very good by the book engines. This is not at all what Andrew is trying to do and it is his money not your own, if he wants to take dollar bills and wipe his backside with them that is his prerogative. If you want to interject advice do so, but to constantly be the heckler in the crowd telling him his faults is petty. As momma always says "if you have nothing nice to say, keep it to yourself."

Plus the engine you are comparing to is no where near the same specifications as the engine I am describing. 74mm stroke 84mm bore with early small bore twin plugged heads. 263hp @ 6800, I called to verify. End of what I'm going to discuss on Andrews thread! So please Drop it.

Andrew,
I am very interested in talking more about where you go with this engine. I will continue to watch your progress! Innovation often has costed many but many have discovered great things while making errors... Plus there are a multitude of folks running iron otherwise they would have stopped producing them years ago.

Thomas

\
Wow Thomas, who peed in your Cheerios?
These were simple questions for which you chose to personally attack the questioner.
First question: considering the output on a factory racing 2.5 engine was 270hp @ 8000, how did your friend get 265 @ under 7000? That's not an attack on you or your information, just a question.
Next question was: were the cylinders cast iron? I predicted Biral but only you can answer that question. Also not an attack.
I do have another question now that you posted bore and stroke: Where did he get a 74mm stroke, 6 bolt crank? That sound cool but how do you make the rods clear the oil pump?

[Lapkritis]

Henry, please accept Thomas' invitation to cross Schwartz in a private message rather than in here.

[Walt Fricke]

Henry

You are right - I got out a magnet and my 88mm EMPIs are Biral (steel sleeve, aluminum looking cast fins surrounding sleeve). I don't know just why I thought they were all cast iron. Maybe because they are a bit dirty, and I was thinking back 20 some years to when I last looked at them.

But Thomas and others so inclined really should stop personalizing things. We all are, or should be, able to distinguish hype from experience, or at least add our own personal yardsticks and grains of salt to what we read. Politeness encourages thoughtful responses, which are more useful to the rest of us. Very few actually know everything about everything, so there are always things for most to learn. Following discussions often leads to gaining some knowledge (how else would I have realized I was under a misapprehension about my EMPIs?) even if not central to the topic. It really is easy to disagree without being disagreeable. Being known as someone who won't put up with guff, and doesn't suffer fools lightly, is all fine in direct personal contexts. But it really is of no value here. If someone says only X is the way to go, it is easy to say "well, Y worked for me" without rolling around in the mud.

And if someone is discourteous, I don't take it as a sign of weakness or agreement if there is no response, or if the response carefully ignores the impoliteness. I view that as a sign of good character.

[tscrihfield]

Sorry to all, hopefully I've cleared it up. Carry on.

[Henry Schmidt]

Originally Posted by tscrihfield

Sorry to all, hopefully I've cleared it up. Carry on.

It's all good at this end, Thomas.
Cheers

[Lapkritis]

Just a quick check in. Been putting the miles on. Runs great, very happy to be squishing bugs again and getting reacquainted with the road manners. Carbs are much happier with some miles.

Breather hose needs to be replaced, leaking and noted a split on reassembly.





I'm not a huge decal fan and try to limit what I do apply to understated and not flashy. Put this one on in honor of the bureaucrats and the related discussion earlier in the thread:

[Lapkritis]

Longest tour so far yesterday. All back roads from Montpelier to Stowe then over Smuggler's Notch and around to Burlington/Lake Champlain for dinner. Lots of hills to allow for variable throttle input to help bed the rings in. Had my fiance along for the drive and car performed without issue. Approximately 250 miles on the job now and ready for first valve adjustment. The car rips, not sure what else to say. HP is not an issue even on mountain climbs. Dyno next? Any other requests for information you guys have on how this performs? Otherwise I may not have anything left to share for a looong time.

[Walt Fricke]

It would be nice if you could post the dyno sheet so we can compare torque curves with those we have gathered from our or others' engines.

[Lapkritis]

Called my local and the dyno is two weeks out lead time. I'm going to wait to book until after the valve adjustment is done. If I run into July(which is likely) then it will see dyno in public for the first time at http://WWW.wolfsgart.com 2013 which is the last weekend in July.

[Lapkritis]

74 911 2.8 iron cyl sprint - YouTube

Shot a quickie (not a Magnus Walker production) over lunch. Still yet to tune or work the carbs over but shows it has zip. Learning the cams really like shifts around 7800 to keep things in the happy zone. Pardon the cell phone shakes and early shift in 3rd to 4th.

Edited to fix video link.

[tscrihfield]

Music, lovely music!

[KTL]

7:31 ring & pinion in the 915 I assume? Goes thru the gears quickly!