advanced cams for retards

[Spliffotticle]

I imagine that it will have to read wot as soon as the throttle peeps open.

Why?

The 100mm throttle opened a tiny bit will allow the same air flow as a stock wide open.

[Spliffotticle]

Why are you using such a HUGE tb on such a small engine? 100mm is big even on most (street anyways) v8's. With F.I. a small tb matters even less.

This is an excellent question sir & I am glad to give my best excuse. It is as follows: Air has mass. When it moves, therefore, it carries inertia behind it. (this is the concept behind variable resonance inductance) Every bend in your system adds hypothetical length to the circuit. It also reduces the speed of the air by creating impedance. When your engine pulls air through the throttle it extrudes it. The stretching of the air reduces the amount of available oxygen to burn. Under load, your engine is actually "fighting" to use the throttle opening because the area of the throttle is ideal to feed one cylinder at a time. This seems logical, as you would only need that. However, if a crowd of people were funneling through one door, into a foyer, to enter 1 of 6 doors you would notice a few problems.

1. Every time a door closes the people in the foyer change direction.
2. The people in the foyer are not crowded.
3. The people in the foyer are hotter from moving around but accomplishing no work.
4. During rush hour (wot) there are people entering the FOYER to use all doors at the same time, making for a crowded entry. A crowded entry (throttle) = a thin foyer (intake)
5. Dropping this analogy for a sec, the longer the circuit from air filter to intake, the slower the air flow. To compensate for pressure drop in all my 3" bends, I used a 4" dump. This makes it possible for me to minimize extrusion, which, unfortunately, is calculated by eggheads @ diamler and accounted for on their throttles.

The bottom line is this: If you had a foyer of six doors and a lot of traffic, you would want the entry to be big enough to accommodate the volume. You don't want to be bumping into people just to get to your door. They always want to stop & bullshit about their kids & stuff

[Spliffotticle]

Lol Easy button... Take it for what it's worth... Square piece of steel, 60ish mm hole, and stock TB. Do your best and RTV the rest. It's not a proper solution, and you will probably have to disconnect your turbo plumbing, but at least you could get your engine running right and determine any build/timing/sensor problems before you take on the boost. Without removing your manifold. If everything checks out, I'd work on the TB from there. It's just a thought....

The plumbing to the intake is disconnected when troubleshooting. Also... I'd sooner just get the other intake complete from the junkyard then silicone a new throttle on. I have done without it for this long. I'll wait until this mule is ready to plow.

[lafrad]

Just an FYI: the 6.1/6.4/7.0L hemi's making 20 lbs of boost and running mid 9's in the 1/4 mile are running stock 80mm TB's. (I think one has a 90mm but it has some horrid street behavior)

http://www.youtube.com/watch?v=L56jAevsjuU

If you honestly think you are building your I6 to be in the same performance class as that engine, then by all means go with a throttle body that is 80mm (bigger would suggest you are making 1100-1200 hp...). I think it will make your life difficult and work against you having a proper running vehicle. I personally think a stock TB for boost will be more than enough for you to get a strong running engine, and be able to address the real sticky points with the setup, before going for the last "2%" of the HP to be gained.



About the camshaft position sensor: its a very simple setup: 50% of it is a solid piece of metal, 50% is open. its basically telling the ECU what "half" of the 720 degree combustion cycle the system is on. Its declared in several manuals, and also defined in the ECU programming guide, that it does NOT change the spark OR injector timing in relation to TDC.. just what injectors/spark plugs to fire on which revolution of the crankshaft. If you are seeing timing changes when moving it, it is because you are probably really close to "cutoff" point on where it determines that 720 split... and the timing dances when it does its rationality checks.


If you are using an aftermarket ECU or piggyback, all bets are off, I don't know how it determines timing without reading about it.


Just an FYI: People here aren't trying to cause trouble with your project... we are just trying to get you to focus on the right things to be successful in your build. TB's and cam sensors are not where you should be spending all your time right now.

[Spliffotticle]

Just an FYI: People here aren't trying to cause trouble with your project... we are just trying to get you to focus on the right things to be successful in your build. TB's and cam sensors are not where you should be spending all your time right now.

lololololol I never thought any one was causing trouble. I'm here because you guys have the solution. lolso, I just figured out something disturbing. I was using the stroker calc and did not realize the advancement was built in, and advanced mine 4* (or 8* crank if I understand this right) so my real number in that lil box is like 8 or 12 or wtf knows but I am retarding my cam first bc that is like a 30 min job havin a beer and then I'll adjust my throttle problem if (when)I have the same or similar symptoms. I have plenty of turbo to make up for lost displacement.

[lafrad]

if you are advanced 8* or more, then you actually probably are having issues with the crank sensor being too close to the cutoff point of the NEXT cyl... and are suffering from the ECU making the spark dance around.

With a turbo, I would actually try to get that cam setup as close to straight up as possible. 108 LSA means "Straight up" is a 108 ICL. which is MORE than advanced enough to get the turbo spooling quick.

[Spliffotticle]

The rain isn't letting me out of my trailer : ( I got that sexy comp double roller pulled so when God gives me a dry window I'll go do some experiments with timing chain settings... maybe even lurn some amathmatic and count up my teeth and see if there are any good overlaps advancing 1 tooth and retarding the cam or vice versa. For now I want to try the straight up and since I'm fairly confident I don't have an interference engine here, also try retarded and see whats up. Valve cover is off bc I replaced my pushrods so I can't do any test drives until I seal everything.

[Jeep's Jake]

Lol Easy button... Take it for what it's worth... Square piece of steel, 60ish mm hole, and stock TB. Do your best and RTV the rest. It's not a proper solution, and you will probably have to disconnect your turbo plumbing, but at least you could get your engine running right and determine any build/timing/sensor problems before you take on the boost. Without removing your manifold. If everything checks out, I'd work on the TB from there. It's just a thought....

The plumbing to the intake is disconnected when troubleshooting. Also... I'd sooner just get the other intake complete from the junkyard then silicone a new throttle on. I have done without it for this long. I'll wait until this mule is ready to plow.

Just to be clear on that, I did mean to actually "build" an adapter plate using the proper bolts. I cheat, but not that badly! It would save you the time and cost of installing a new manifold and/or gaskets just to see if your troubles were actually caused by the throttle setup.

Be sure to let us know how the timing chain adjustments go. It might be worth tearing mine down again. If only it took me 30 minutes...

And not trying to cause any trouble, but I was told you want a larger lobe separation angle when running boost. Is there any truth to that?

Sorry, new guy here - bear with me.

[Spliffotticle]

This is precisely why I started this topic. I would be obliged to have a cam educator post us up some layman's camology.

[4.whoa]

I was told you want a larger lobe separation angle when running boost. Is there any truth to that?

I just saw an article in the june '11 carcraft on turbo cams. It says that with higher back pressure(mostly older turbos) you need the larger lsa ,but with lower bp(newer/better turbos) you want a tighter lsa "just like on a n/a engine"