High compression with aluminum heads and pump gas???????

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rumblefish360 said:
Bullshit!

^^^^^^ Knows nothing!
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Well im just saying what my engine builder told me, has been building engines for over 30 years. Todays gas is not what it used to be

Real mature comment, instead of downing someone for theyre opinion why not take more than 3 seconds and come up with a competative agruement on why you think i know nothing. Real knoledgable guy to say i know nothing only to not explain why what i said is bull. Higher comp engines usually require higher octane
 
71
your argumentative response is flawed
If you repeat what you heard, instead of what you know,You have no foundation from which to argue.
And if you have been following along,by this time you should have had a reasonably good understanding of why 10:1 and premium, is BS. If its not sinking in, Just keep studying. I didnt learn everything I know on the first go around either.And since other guys on FABO are waaay smarter than me, or have waaay more experience, I assume I have much more yet to learn.So when I'm wrong I just own it. I hate that,sure, but I gotta do it.
 
Trust me i will be the first to admit im wrong, i understand from reading the thread on why, i was just simply stating my opinion on what i was told, just uncalled for, for people to act that way. Sorry op for getting off track
 
Who determines that 11:1 is high compression?

Who determines a 6.123 is a long rod?

Compression is neither high or low. It is what it is. Just like rod length.
 
12.85:1 and aluminum heads.........040 quench.
Runs like a dream on pump gas.
Of course , it's E-85.
96 at the pump in Brazil ?
How much a liter ? I definitely dig your style.
Much of Europe has 98 to 100 octane available at the pump too......but then , they tend to love their cars. ;-)
 
416cid/alum/9.7Scr/7.74Dcr/63*ICA/91octane Calif spec/.030Quench/full timing up to 31*/750altitude

416 cid 4" stroker 0.030 over 340 block.
aluminum "63cc" Edelbrock LA heads measured at 64 cc actual
9.7 Scr measured with CC'ing heads, micrometer piston height
7.74 Dcr
63 deg ICA from here: Comp XE274-S solid http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=670&sb=2
91 Octane California spec gas "up to 10% ethanol"
0.030 quench
full timing up to 31 degrees
750 altitude at my home town

2500 ft altitude at Willow Springs Raceway.

Dcr calc here: http://www.wallaceracing.com/dynamic-cr.php

On the verge of pinging. Will ping going up long steep grade full throttle acceleration starting from 3,500 rpm (75 mph) upward headed toward 5,000+ rpm.
 
Good idea.. Would be possible if I actually kept a cam card on hand or know where some of the old ones went.
Not every body gets it ether. I try to keep it simple without opening up a can of worms.
 
AJ/FormS said:
71
your argumentative response is flawed
If you repeat what you heard, instead of what you know,You have no foundation from which to argue.
And if you have been following along,by this time you should have had a reasonably good understanding of why 10:1 and premium, is BS. If its not sinking in, Just keep studying. I didnt learn everything I know on the first go around either.And since other guys on FABO are waaay smarter than me, or have waaay more experience, I assume I have much more yet to learn.So when I'm wrong I just own it. I hate that,sure, but I gotta do it.
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Thank you, ditto, and sorry to the offended. Your engine builder knows nothing and should be avoided. Truly the combo needs to be know before a call can be made on what will or won't work with what fuel is to be used.

Example:

11-1 iron head and small cam, not good.

11-1 and a big cam, OK

While that was ridiculously general, it is a basic idea that will hold true.
 
How does he know nothing, i told him i wanted a strong street car to run on pump gas, and he suggested to stay around 10:1 comp, maybe he was just being on the conservative side, he suggested to shoot for 10:1 comp and not run a higher amount of comp

He is a reputable engine builder and builds engines for people all over the country, also has built a couple engines for baja racers

I guess what made him originally say that is i was going to use iron heads but they failed the leakdown test and leaked between the valve seat and head, so had to go the aluminum route
 
Mad "Who determines that 11:1 is high compression?

Who determines a 6.123 is a long rod?

Compression is neither high or low. It is what it is. Just like rod length. "


71DodgeDemon340 said:
How does he know nothing, i told him i wanted a strong street car to run on pump gas, and he suggested to stay around 10:1 comp, maybe he was just being on the conservative side, he suggested to shoot for 10:1 comp and not run a higher amount of comp

He is a reputable engine builder and builds engines for people all over the country, also has built a couple engines for baja racers

I guess what made him originally say that is i was going to use iron heads but they failed the leakdown test and leaked between the valve seat and head, so had to go the aluminum route
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Answer to both these is the OP's builder.
71 - If you want information on what many others are doing, or to understand how the parts combine to make an eingine run a certain way, it's a good post. If you're looking to validate what your guy said to you, it's hard because there are those of us that might push things higher, and others that would say you builder is nuts for going that high...lol. If you trust your builder, let him guide you. Ultimately you pay him, and if you're not happy he has to deal with you on it.

edit: - your original question was what do you look for for issues: cam choice, piston choice, and down the road timing andd carburetion tuning all are areas to watch out for.
 
71DodgeDemon340 said:
How does he know nothing, i told him i wanted a strong street car to run on pump gas, and he suggested to stay around 10:1 comp, maybe he was just being on the conservative side, he suggested to shoot for 10:1 comp and not run a higher amount of comp.
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I suspect you nailed it. If I was building engines for anyone who walked in the door and who might not understand engines and who I did not know for sure would take care of the tune for a high CR engine, I'd be conservative too. There is too much chance for someone to abuse it and not keep it tuned or put in regular/crappy gas, and then have detonation issues and come back and blame me. With the social media access for people to put out all sorts of nonsense and lies, you gotta be careful, and we ALL know guys who will beat the crap out of engines and then blame somebody/something else. My local machinist who has built gobs for race engines for the local circle and drag track in all classes, went conservative on me last week when I mentioned 10:1 CR. I'll listen to his input but move forward on my own judgement.

KrazyKuda's post is good 'cuz it ID's the edge of detonation for his setup, and under what conditions. That info is as important as what is working well. Some drivers will put the engine under difference loading and one who drives higher RPM's and does not lug it down will have more success with an aggressive CR combo than some other driver's.

One missing part of the info for folks new to all this is what can be done to solve a mild pinging/detonation situation; it is not always a lost cause if you stray over the line. It can be solved to varying degrees with less ignition timing, cam retard, higher RPM's (TC stall speed, rear gear, long shifting), cam changes, and tune changes. Catch it in time and correct things.
 
Exactly, i wanted a good reliable strong 340, that i didnt have to constantly check/tune like you would a race engine, i was just folowing my engine builders reccomendations, i trust him and have been extremely happy with engine, havent had to adjust anything engine or carb in years
 
JMHO, that is a solid reason to stay lower on CR.... just like the factory did for stock engines. The /6's and 318's tended to last well if not spectacularly. Low CR? No problem!
 
As in everything, "Point of view" is in play.
 
The truth is,for a streeter, once you get the the Dcr to within about 90/95 per cent of what the fuel octane will support, further gains are almost not worth chasing. You would be looking at very minimal power increases, and even less increases in fuel economy.For someone like me, who is not interested in mph/ET, A sweet running combo, that doesnt have to be constantly tweeked,and burns 87E10, is a desireable thing.I know that I am right in that range, at 10.7Scr/8.5Dcr. And time has proven that the combo is sweet!
Having learned so much since 97, if I was to do another, non-stroker-sbm build, the only things I would do differently, is to go with custom pistons, and machine the block as little as possible, if at all, and probably a roller cam.All the headaches I've had with my 367, have been due to faulty machining.
And I think I might try some aftermarket iron heads.
 
AJ/FormS said:
Auto X,
nice post. See those are meaningful numbers. Ima guessing those pistons are dished with a quenchpad?

My topend is very similar to yours.
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20cc dish Icon pistons Scat sells with their stroker kits.

And looking back at my numbers the Edelbrock "63 cc" heads are actually 65 cc. Looked back at a post that MRL Engines confirmed/found the same thing.

attachment.php
 
Yup, that'll do it.
Thx for responding.

As to my Eddies, I never measured them. I assembled the engine, flipped it on its side with a plug hole facing up. I poured in oil to the bottom of the hole and measured the fill volume. I knew my deck height,and the head gasket's published ccs,so it was easy to do the math and figured the Eddies at a published 65cc were pretty much right on. Then I ordered my cam(which I had targeted) to get the Dcr that I believed would run on 87E10. I set it up with a thin headgasket, the idea being that I could lower the Dcr if needed by going to a thicker gasket. Well at crs of;11.2 Scr and 8.2Dcr, the 292/509, was right at home.
That was the first of 3 cams.
 
tubtar said:
12.85:1 and aluminum heads.........040 quench.
Runs like a dream on pump gas.
Of course , it's E-85.
96 at the pump in Brazil ?
How much a liter ? I definitely dig your style.
Much of Europe has 98 to 100 octane available at the pump too......but then , they tend to love their cars. ;-)
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Hi Tubtar,

I was wrong. In Brazil we have 95 at Podium Pump Gas but we have a federal law that forces that all types gasoline must be 25% of Ethanol. Price is around U$: 1.30 per liter.

This is a problem when Brazilian costumers buy a Edelbrock carb. Normally we have a lot of problems with corrosion...

Attached a table with comparison between most popular types of gasoline in Brazil.

Diego
 

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11.8:1 in my 408. Eddy RPM heads. I run 93 octane most of the time when I tune it down, and 110 octane when I tune it up and want the extra power.
 
rumblefish360 said:
Bullshit!

^^^^^^ Knows nothing!
Click to expand...

Actually 10:1 with aluminum heads for pump gas is a good solid recommendation. Look at Autoxcuda's combo and you'll see that his engine will ping on pump gas at 9.7 compression. Lots of variables to play with but 10:1 is a very reasonable number.

If you want some proof then go look at the specs for production high performance cars. Most of the high performance cars made these days are in the 10:1 range and they are morre sophistacated than anything we build. They have knock sensors, computer controlled ignition timing, computer controlled fuel injection, etc. If you don't have the automatic compensation systems then you have to dial the base engine design back a bit.
 
Auto X
When I punch your numbers into the Dcr calculator, it spits out a Scr of 10.3, and a Dcr of 8.37. Now I know I must be doing something wrong.I am in no way implying an error on your part. I guess those special pistons are hard to figure.
Ima guessing the 20cc is not a net figure,typically arrived at by adding the dish and the quench-pad together, but rather just the dish, and the piston rim must be down in the hole some?
So the total fill volume must have come out to about 98/99 cc, I imagine.
And the final compression distance puts the quench-pad proud of the deck by .009 with a .039 gasket, to arrive at .030Quench.
Your thoughts?
 
I am running 10.2 with iron r/t heads and 94 octane with no problems at all.
 
My 273 - 12:1 with iron EQ 318 Magnum heads and solid roller cam uses
98 RON octane here in Australia (91.5 in the USA)
 
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