Disc Brake Hold Off & Prop Valves
comments in the quote
Good Lord, you're an encyclopedia of Mopar knowledge. I know you said you've come to this set up after years of trial and error but, man alive, you've got it down to every detail. I do get it though, a guy should know his car, I think it's amazing that you have that kind of attention to detail.
So, .549/.571 lift with your duration gives you enough vacuum to run the single D brake booster.. Yes,lol. Current cam is 276/286/110; .050s of 230/237 Get the T-port sync right, and it idles right down to 650 pulling 3650 around the parking lot at 4.8mph. With a little timing retard. It will go to 4.0, and with a bit of toe on the clutch, a we bit less. This with a 3.09 x 3.55 startergear.
good to know. I gotta ask though... 87 gas? Yes always; Oxygenated is all we have, unless you go hunting for the other; I haven't seen it since 1999.
Where is your timing set? Full power; with aluminum, and on the street, my butt dyno could not tell the difference from 32 to 36, so I set it to 34/32 and it's never been other since 2000. I'm at 14/16 idle, increasing to 28*@2800, then slowing to be all in at 3200/3400. Yeah, I'm running a teener fat boy spring in there.And one almost sloppy loose one. And I run a 22* Vcan,on spark-port, and in as early as it is able to come in.
You feel like you're getting enough detonation from that? Funny guy, see below
I don't, for a minute, doubt what you're saying. I'm just trying to learn what set ups are successful. Thanks again for your time and insight.
Aluminum heads don't work like iron. At Least that's the opinion I have formed. It goes like this;
Some 85% of a streeter's life is spent at 4000rpm or less, about where the combo torque-peaks. And it's rarely at WOT. You only need detonation-protection when the chamber temperature exceeds the anti-detonation capability of the fuel . So why is your heavily throttled engine tooling around at an effective 5 or 6 or 4 to 1 compression ratio? That was my thinking; why am I buying expensive top grade gas, and just burning it up?
So back to alloys. Aluminum heads extract a ferocious amount of heat outta the chamber, converting it to heat.......instead of pushing you down the road. So now your heavily throttled 5/6/4 effective compression engine is operating at even less efficiency, and so it's no wonder it sits in the carport all week.
So my thinking was, what if, knowing this now, I cranked the compression way up, and promised not to floor it with a flipping huge air valve? Hmmmmmm.
Back to alloys. The thing is this; it turns out, that there doesn't seem to be enough time during a typical street blast of 3 to 6 seconds, for the chambers to get too hot for 87E10. There's just no time! I can't say for a road racer. I can say that my engine has survived thousands of blasts to 100/110mph,since 1999, when I built it. Eight to 12 seconds evidently is safe. But I have a rock-solid cooling system which is able to shed all that heat, which shortly comes around.
That's my theory. And I'm gonna push more pressure next time, cuz more pressure means more part-throttle efficiency. And more pressure means more power. Now, I don't need more power, so I'd be taking cam out. Perhaps a double whammy of torque increase at PT and lower rpms. Perhaps a smaller rear gear, with no loss in performance. Perhaps near30 MPGs with the GVOD.
I'll tell ya; I'm never going back to factory iron heads. Probably never to iron at all. If there was available a lower-priced, lower-octane grade of gas, I would be experimenting with that.
I'm not saying alloys are molasses on pancakes. I'm saying I've had a great experience with mine. And I highly recommend experimentation. And I don't hold back on what I've learned; you get it for free from me.
Oh one more thing; on the hiway, after the head temp has stabilized, you can, I mean I could, lean thechit out of her, and point-to-point, get phenomenal fuel mileage ,so much so,that a few people have immediately called me a liar. Well they didn't actually say that ; what is usually said is "that's impossible" or "I don't believe that", or some equivalent statement. So I don't quote those results any more. I can tell you this, with a stout 360 there is no reason to not drive a low-12 second car as a DD. Your EFI Honda will get better economy around town, by virtue of it's big-dollar design, and small displacement, but point-to-point, It ain't molasses on pancakes either. Well, compared to a 9.5 iron job maybe,lol.
I tell you what, over 100,000 miles of aluminum headed operation, I think I saved enough money just in the fuel savings of 87 versus 93, to enjoy a free freshening up,at least once every 5 years. So I'd be on the third one now. Never mind the thousands of miles further it mighta drove. The cost difference here,in Manitoba,is about 20/25cents a liter; or about 91cents per gallonUS. That's an annual fuel cost savings of from $600 to $900. That's
savings. What's that come to in say 5 years,lol?
Never mind if the 185psi drives 2 or 4 or 10 percent further on a dollar of gas, than the 155/160 that most iron headed SBMers run.
So what's not to like about alloys?
Well, they do convert a lot of energy to heat in city traffic. You have to have a great cooling system. And You have to keep the inlet air temps down. This is waay cheaper than running extra gas for cooling.
And if your heads are hot, your exhaust will be too.....So it's gonna be harder to get rid off through those wiener 2.25 pipes and Wally-Mart mufflers. Lol. I run a minimum water temp of 205*F. Min-i-mum. This to help capture some of that energy to the crank. And I run twin 3inch pipes right out the back to get those hot expanding gasses outta the chambers, and to help the headers do their thing,especially during overlap.And I try to run extra duration during the power cycle to try to extract a lil more energy into the crank. This runs contra to most guys thinking who will gladly sacrifice extraction for exhaust duration. And that's fine for racing. Terrible for a a broke-azz streeter, trying to keep his fuel tank from being empty all the time.Yeah so, next time it's gonna be a solid FTH to give a lil more time to that consideration.
Boy you wanna talk about a cam that sux gas, look at the 292/508/108 Mopar grind. In at 104, the power cycle is just 102*. Compare that to a 268/276/108 solid in at 108, that has 114* Yeah so that doesn't look like much, but it's 114/102= an extra 11.8%..... that's about an extra eighth part . You have 8 fingers; which of those would you call extra.lol.
Yeah I know, the 292 is on a nuther level from the 268. the 292 is about 251@.050IIRC. A solid 268 could be a 230@.050...so that's about 3 cam sizes. I'll tell ya, on the street, I'll take the 230 at 185psi anytime over the 251 at 155/160 in iron. I've run both, and 251 didn't make 12 months. Actually,driving, it didn't make 3 months.
Anyways, enough rambling.
