Are throttle body spacers worth the cost?
Do they do anything positive or negative for power on their own?
Do they only make a difference when paired with other engine bolt-ons, like long tube headers and performance exhaust, cold air intake, and fuel system upgrades?
Just to give more info on my application, I drive a 2006 4.7L v8 4x4 Toyota Tundra with variable valve timing and a 5 speed auto, on 33 inch tires. I currently have 270cc 12 hole fuel injectors (upgraded from 4 hole injectors, both OEM and upgraded parts made by Denso), Airaid modular intake tube paired with OEM air box and a high flow filter, and OEM exhaust with the resonator removed and a Flowmaster muffler. I'm looking to gain low end and mid range power, I think the top end is fine as is because of the VVTI. I would like to eventually upgrade the entire exhaust system with long tube headers and dual exhaust eventually. Then re-gear from 3.91 to 4.56 and install a URD MAF calibrator,
I figured these mods would give me the best scavenging effect and might be complimented by a throttle body spacer.
Thanks again for your help.
@jhoover
I appreciate the kind words... and sorta don't like typing this...
Your looking for low end, where flow velocity and volume is lower (both, intake and exhaust)... thus scavenging will be reduced (tuning the pipe lengths/connections can overcome a lot of this but can get difficult). This is why short intake runners are used on engines that have a fast throttle response (quick rpm increases). Consider how far the air has to travel from the throttle body to the cylinder, the shorter this distance the quicker it can get there (remember there is a vacuum between the TB and the valves so the time it takes to get VOLUME to the cylinder will increase with runner/plenum length. Also, I believe the VVT on that engine is mostly from a lookup table in the pcm that couldn't take these physical manifold changes into consideration (of course there's reprogramming). And a little confused by wanting low end and installing injectors that provide more available fuel than can only be utilized by higher rpm (else you won't be running a stochastic mixture). Forced air (turbo or super) would allow more fuel and air at lower rpm while keeping a stochastic mixture (proper fuel air ratio for complete burn of all fuel and O2). Now all this is fun to play with but to know, you'd need to dyno 3 times, change parts, dyno 3 times, repeat with all parts (and try to do on a consistent barometric pressure day). The biggest change your gonna see is the power increase (low end torque) from the gear ratio change you mentioned.
Just to clear things up a bit, the injectors are basically refurbished OEM Denso injectors, they aren't any larger or different beyond the number of holes for better fuel atomization. In a dyno test run with the Dirty deeds Industries 4.7L Tundra, the new injectors didn't yield any more horse power or torque over the 4 hole injectors. But did widen the power band. I've also seen an average of 20 more miles to a tank in the last year I've had them.
@jhoover
My bad, I shouldn't have assumed you got injectors that delivered more fuel.
Yes they are worth the cost in certain situations.
Yes, but depends on where you want the power improvement, low or high rpm (torque and HP implications).
Yes but all parts need to compliment each other.
So let me elaborate on what happens here, air has mass and thus momentum. So a faster moving gas has more momentum and other things being equal, air moving faster can fill the cylinders quicker and more completely (the increased momentum helps keep more velocity as it goes around the valves thus filling the cylinder quicker/more completely). Now, as you should be able to imagine there is a "sweet" spot where intake plenum size, valve size and etc provide an rpm spot where the engine performs better. Well engineers have to design for a range thus decreasing the "sweet" spot performance to improve operation over the whole operating range the vehicle is designed for.
So this is were they can be an improvement for you, if you have a vehicle you want max power at some range or spot, all these things can be adjusted to do exactly that. Now it's not as easy as just ordering a spacer and putting it on, things need to be measured as spacer sellers don't make a lot of claims other than it improves everything without any regard to how your operating the engine.
So the chances of you ordering one and putting it on and making an improvement is slim...unless you know specifics beginning with WHERE you want an improvement in your engine. So for a daily driver it mostly hurts performance because its adjusted for a specific area for improvement while decreasing all the other rpm areas... other areas of where you operate the vehicle. If you have a toy (race) car you operate at the higher rpm most of the time, yea you can get an improvement if engineered with other components to improve power in the smaller operating range you desire.
Looking back over this it may seem complicated and dry... let me give another example that's the same thing...
You've heard cams put in race cars to get more power and hear that lovely low rpm lobing sound... which is actually the engine running like crap at low rpm because of such low airflow/varying cylinder filling...but will run like a beast at higher rpm...where it's desired. And here's where it the same as the spacer...it's about getting air in the cylinder quicker and more completely. Same thing is happening at high rpm where you see engines on dynos start losing power as rpm increases (actually 1 of several reasons this can happen).
Iterating again, so daily driver with large operating range...hurts having one. Specific application, yea, any tuning to increase airflow at that rpm/range for the specific application will improve performance.
@hillbilly
Thanks for the well thought out and informed response. Thumbs up!
@jhoover
you can actually thumbs up his answer with the up arrow on the left side!
@Fernd Thank you. It'll take folks some time, including me, to get a good operational hold on the forum...quite a bit of work coming in too!
Hello there! Throttle body spacers on their own do not have noticeable effects. They should be paired with a cold air intake to feel a difference. I installed a throttle body spacer and INJEN cold air intake on my 2008 Mazda 3, and I definitely felt a difference in power. The spacer is designed to swirl the air into a vortex to allow for a better mixture with the fuel. It's the same idea as having pistons with swirl cavities. Having that free flowing intake will allow for a better vortex, which is why pairing them is best. They actually work, but you need to get a good quality one from a well-known manufacturer. Happy modding!
@razmigb
Vortex flow is tricky and can help or hinder. It is not what engineers prioritize when designing them. Here's where it's bad, too much vortex can cause significant differential pressures in the plenum and entering the cylinders. These pressures are indicative of amount of air and thus affect fuel air ratio. Again variables like where fuel is injected has significant effects.
Thanks for sharing the more technical stuff. The experiences I've had with throttle body spacers were all good. They are specifically engineered to help improve engine performance. Realize that time and money is put in by performance-oriented manufacturers to do research on these stuff.