Like the title says. What are the most common mistakes we make when we tear into our engines, and how do we avoid them?
Steve, the most common mistake I see causing problems is someone not knowing whether the result they now have with a replacement part, a performance part, a tune modification, etc., is correct. It"s a farse to think taking a part out of a box and bolting it on is all that's needed, especially when it's an attempt in resolving a bad state of tune, and even more so with efi than carbs. Experience allows you to recognize potential problems when a teardown to any degree is performed. Lacking that "experience" can be a problem, but this is how we all learn, myself included. My opinion is a person has to be patient, and open minded when attempting any type of work to any engine, or peripheral. I think cutting corners is also a common problem, negating proper stages in work is a bad thing, and can lead to a worse result than what the situtaion started as.Like the title says. What are the most common mistakes we make when we tear into our engines, and how do we avoid them?
This is a good question that I've been kind of wondering about since I built my motor. It's nothing huge, just a cam and a small bore (.020), and cleaned injectors are the big things, of course along with all the other standard new parts. However I know that a cam can make a HUGE difference in the way a motor runs. I'm sure my tune is complete crap, and wish I knew as much about engines as I do steel fabrication.In your experience, at what point (in terms of modifications) do you have to seek EFI tuning?
Ok, reinstalling 3VZE heads.
You mentioned that was a big issue, so what makes the 3VZE that much different that working on any other top end?
Darin, this will get deep, but your up to it. It depends on the ECU driver, different years are different, injector cc's were increased as the later years evolved, ohms changed, high impedance vs. peak and hold, saturated, etc. O2 sensors changed, upper chambers and throttle bodies changed. 83-84 efi used carbed distributors and a different tps so the ecu had no effect on timing. Altitude, climate, terrain, it all comes into effect. It all depends on what the tuning shows before modding takes place. That's why I tell people "You have to watch the tune up." Adding performance parts to a bad tune shows greater losses than one would suspect. Guys here that grew up on old school domestic and dubs know this all too well. Look at it like this, when a 4 banger making 100hp losses a cylinder, say by yanking a plug wire, you in theory lose 25%, drop a cylinder in an engine makin 200hp and you lose in theory 50hp. This is going to show on a grander scale. Duty cycle and loads play into it also. You have to seek tuning from the start, compensating comes into play from there.In your experience, at what point (in terms of modifications) do you have to seek EFI tuning?
More than you'd actually think. Here's something that really needs to be known. R-series heads, from the get go, do not flow equal from head to head. Castings go from almost perfect to total yuk. I've bought new heads from Toyota that could not be ported without welding in material. The difference a cam makes in an engine (22r,re,rte) is going to depend on the intake to exhaust flow deficit, the actual casting, seat undercuts, core shift, and overall combination, just to name a few factors. You can take any cam out there and bolt it in your engine and come out with a hit or miss, and this is because those factors are in play. Bigger bores are a huge player in this because the bore becomes an extension of the port itself. Valve sizing, seat and face angles, stem undercut, ramp profile, etc. COMBINATION!!However I know that a cam can make a HUGE difference in the way a motor runs.
I wish I knew that field..I'm sure my tune is complete crap, and wish I knew as much about engines as I do steel fabrication.
Not certain what you mean.What kinds of simple things can be looked at when running a high lift cam?
Motors are individual entities, they require tuning as a specific unit. You can build 2 indenticle engines, and both will want exactly what they want. No "generic" tuning, tune your engine for what it best likes.Also in my case I took a block and head, replace the head, and put the EFI system from my running motor on the newly built block. Aside from the Cam, injectors, and bore, should there be much of a difference in the operation/tune of the motor?