I know I probably should change the sensors anyway, but think I'll wait and see if the code goes away with the new intake and gaskets (and injectors, plugs, etc.) if so, I'll also wait until it's warmer to do so.

Unless you're going forced-induction or doing something else radical, you'll likely never out-flow the stock TB or peg the MAF.

 

Could anyone use a set of Bosch front rotors used just 5kmi?

 

Doesn't a large throttle body, by definition, outflow a smaller one?

When I had my 87 300ZX Turbo, I swapped in a larger throttle body from a Nissan Stanza (240sx has same TB) and it definitely made a difference. Went from 54mm to 60mm and dyno gain was 14 rwhp with stock fuel maps @12psi boost. While that gain was tied to other upgrades surrounding the tb, the actual power came from the higher flow through it.

Not sure if I'd go forced induction, but with a rebuilt engine I might spice up the cams and use higher compression pistons...having the infrastructure in place for that might be a good thing.

 

No, the CID determines max flow, so beyond a certain point, larger TBs just slow the airflow.

FI changes that because now max flow is limited only by whether your bottom end can stay together.

 

It has the *capacity* to flow more air, but increasing its size will only help if the original one is posing a restriction to airflow. You need to look at the entire intake tract/engine/exhaust as a system. If the stock TB (and MAF) are capable of flowing the amount of air being sucked in by the engine, then making them bigger will only slow the intake air velocity and potentially introduce drivability problems like surging and twitchy throttle response.

Boosted applications can respond better to improvements in intake airflow because the turbo (or supercharger) is trying to cram air into the engine, so removing restriction might prove beneficial. It's also possible (actually probable) that if the slightly larger TB helped, it was *in conjunction with* the "other modifications."

As noted above, bigger is not necessarily better. MAF, TB, Intake tract, intake, heads, cams, exhaust... all components should be selected in proper combination so they match the performance needs of the system. I would suggest making your engine mods, then checking to see if the TB (or MAF, or intake tube, etc.) is, in fact, a restriction before throwing money where it doesn't provide benefit.

 

Truth.

 

Isn't that all a factor of volumetric efficiency? After all, the have 1.8l cars pushing 2,000hp often at the drag strips...yes your internals have to be up to it but you have to have the flow to get there.

Suck, squeeze, bang, blow...the easier you make it to do those four tasks, the more power you have in the giant air pump we call an internal combustion engine...turbos and superchargers increase the amount of air being pulled through, as does higher compression pistons, that's the direct force being applied. You have things like ram air systems which help, but the fundamental issue is allowing the system to breathe easier. removing restrictions does that.

The throttle body is one of the few places where you can actually gain in available power without sacrificing overall gas mileage, simply because it is a metering device that regulates how much air is allowed into the system. As they often say, the best determination for gas mileage is how much lead is in your foot.

Larger throttle bodies only slow the airflow when the rest of the system is unable to supply it, such as when your maf and intake plumbing is of a smaller diameter than your TB or the source of oxygen rich air is not sufficient to supply the system because it's limited by air sources. Solving those issues, you have exhaust limitations on the other side of the pump(aka combustion chamber), and the most relevant limitations to this discussion, the stock fuel maps, which I've read support up to and just over 300hp (although I'm more concerned with maf/pcm compatibility in this case).

When the throttle plate opens it doesn't go from closed to full open instantly, and as a result, a larger TB and a smaller TB can flow the same amount of air at incremental levels and generally do...to a certain point.

The difference between is that the larger tb has more air available at wide open throttle and a certain percentage approaching it, but otherwise has no marked difference at lower levels, such as occurs during general stop and go driving or cruising at highway speeds. In other words, unless you're stomping on the gas, it should be similar to the smaller throttle body in performance, except that it takes less pedal work to achieve the same power results, much like the gotts zip tie mod, except with the throttle plate and not the throttle cable. The differences would only be truly seen at about 80% throttle or above...

Long story short, Ohio's right in that you wouldn't see maximum benefit without either forced induction or an increase in compression, but that doesn't mean that you wouldn't see some improvements.

I didn't do a half @$$ed port and polish on my tb elbow and upper manifold because I expected a ton of power right now, but it's something that will matter later on a new block with more going for it, and it does help flow to do so, even if it's not going to jiggle any needles in its current state...

​​​​​​To me, my truck is half show half go...fun to tinker with but I limit my projects to a weekend hobby because it occasionally, to quote Jack Reacher, hauls more than a keg of beer from time to time. Still haven't cleaned the mud off my floor mats because winter just cakes more on...

I like the idea of better looking with more power, but I'm not gonna strap on a big gaudy supercharger and a six inch lift to turn it into what, where I came from, we called the "Mendocino County Limos". (Anyone know what that refers to?)

Plan to get a replacement block and tranny with some nice internals, mild 2" lift and decent rims to go with the bushwackers I have yet to put on. Finish out the rustproofing when the weather clears up, and then paint it black (would love a matte black, but from what I have seen on other trucks it scratches too easily and is too hard to fix, so gloss black it is). All this, of course, is after the mortgage is locked in.

Got it with a clean frame but gaping holes in the rockers and bed corners...a little cutting and welding later and they look like factory with very little Bondo. Cleaned up the engine peripherals (sensors, valves, etc) , and just finished the fuel pump to round out an overhaul of the fuel system. Doing lighting upgrades and installed new speakers and android head unit.

This is my keeper truck because I'm not really impressed with most of the newer model trucks with regards to styling, reliability, and definitely not at the ridiculous prices they're being advertised at these days. A truck shouldn't cost more than a home after all, and some of them do, both to buy, and to fix.

​​​​​​

 

Thanks, Ohio...you pretty much covered all the bases with that response...should have looked before posting.

 

Oh damn... I applied here recently.

https://kutv.com/news/local/northrup...aZp_xlhRv7wYfM

 

That's terrible, White! What's probably worse, though, is that my mind immediately went to "workplace shooting." What a world we live in today.