Monitoring Boost

[1973Guppie]

So I am going to be installing a supercharger on my 1996 fzj80. I plan to do the HG and rebuild the top end (valve job) as well as preventative measures to handle heat issues (blue landtank fan clutch, hood vents, intercooler with scoop, aluminum radiator, aux pusher fan for low speeds).

My question pertains specifically to whether or not it is truly necessary to monitor the boost levels in the system? I don't plan on changing the pulley size on the SC and from what I have read it seems that if you leave the system as TRD suggests that everything should work fine. I believe in more is less and don't really want another guage to read if it is not necessary. That being said, I know alot of guys with the SC run a boost guage. I don't plan on doing heavy towing, although I do tow a small tent trailer but it is light (under 2k pnds).

So what is the real purpose to monitoring boost? I would think that the TRD system stock would only allow so much boost and would be safe to use in all conditions?

Appreciate the help.

Noah

 

[1973Guppie]

bump, anyone?? bueller.....

 

[Delancy]

Deleted for lack of viable content, not that I was insinuating I knew chit about. Haha.

 

[scottryana]

The stock TRD system only allows about 6psi of boost. You really don't need a boost gauge. The gauges that would be important are AFR and pyrometer, and really neither one is an absolute must. If you run the stock charger and pulley and add an after cooler of some kind you should be perfectly fine.

 

[DSRTRDR]

we don't have a boost gauge - CDan says it's fun to watch, though

get the finned fan instead of the ring fan - CDan had a thread about that a while back - here's the link https://forum.ih8mud.com/80-series-tech/55521-tools-r-us-bad-dude.html

we are installing the finned fan as we speak - #16361-61020 . . .

 

[djsixbillion]

Pretty much agree with what's already been said - the boost gauge is definitely not as crucial as AFR and EGT. It does provide useful info though; for example when encountering a highway grade you can see the boost start to rise, then you have the option of shifting into a lower gear to raise the engine rpm and get back to negative manifold pressure, theoretically using less fuel to maintain the same speed. Geeky yes, but I often drive this way, "playing" both the boost gauge and AFR to stay in the efficiency band of the engine. Hey, it helps pass the time on longer drives if nothing else!

 

[1973Guppie]

bumping this thread for an update. I have decided to slap on a 2.8 pulley to see how the truck performs. Any benefit to running a boost guage when running a smaller pulley? Is there a psi you should always try to stay under? I am assuming from what I have read that these engines should be able to handle a 2.8 pulley just fine.

 

[jfz80]

I would not worry about the boost level still. The motor can handle the boost that pulley will provide; its the heat that will be much more important. Ive held off on a smaller pulley cause i felt id want an intercooler if i went that route.

Water temps and EGT would be what i would watch.

I agree with what Ryan said earlier AFR and pyrometer would be the guages to look into if you wanted.

 

[lastresort576]

I think it's a good idea to get a baseline with the boost gauge but once you find that out and you are within safe limits especially when going S/C you don't need one anymore...Also does anyone make an IM gasket that helps prevent Heat soak?
If turbo you're a lot more prone to boost spikes and wastegate variability's. It's also nice to see the boost drop off when shifting for reassurance that you're not getting compressor surge. Again this is for a Turbo setup and yea.

 

[Heckraiser]

IMO, with the S/C, the boost you get is the boost you get. Based on pulley size and should not change. Nothing to monitor, although it might be nice to hook it up a borrowed gauge once just to see.

 

[scottryana]

Boost gauges are good diagnostics tools mostly for turbo setups. They can show overboost, underboost, boost leaks, etc. On a supercharger not quite as many potential issues with boost leaks. But when changing from pulley size to pulley size you do need to have an AFR gauge to make sure the new pulley isn't causing you to go lean with the extra boost.

 

[1973Guppie]

Boost gauges are good diagnostics tools mostly for turbo setups. They can show overboost, underboost, boost leaks, etc. On a supercharger not quite as many potential issues with boost leaks. But when changing from pulley size to pulley size you do need to have an AFR gauge to make sure the new pulley isn't causing you to go lean with the extra boost.

thx @scottryana, do you really think an AFR guage is necessary when dropping down to a 2.8 pulley? I decided to swap one on as it is very simple to do, 5 minute job with an air gun if I need to swap back to the stock pulley. I have a scanguage and can monitor the engine temps. I plan to watch those closely when using the 2.8 pulley. I am not interested in putting an intercooler on or modifying anything else. If the 2.8 pulley causes issues I will just swap it back out. Is there any way to monitor lean issues via symptoms? ie: pinging, etc?

 

[lastresort576]

With forced induction of any kinda AFR's should always be measured via wideband o2.
And any time that you change the setup/increase boost you should retune in order to get the most out of the setup.

Megasquirt used to be big for toyotas 10'ish years ago. I'm not sure what's used now a days though.

 

[inkpot]

I run both a pyro that came on the rig when I bought it, and a combo vac/boost that I added. They are about as useful as you make them. Like the factory gauges, they tell you what's going on, IF you happen to look at them. I use the vac/boost gauge the most. It shows IF I am in boost and how much. I like to stay in vacuum as much as possible. Partial throttle at higher rpms is handy for maneuvering in traffic. Makes it easy to acquire blend speed..

 

[1973Guppie]

and to update this thread I did not install an intercooler or hood vents. Engine is basically stock with trd supercharger and 2.8 pulley.

 

[Tapage]

I see a boost gauge some sort of troubleshooting gauge .. if your engine rely on boost and you notice and drop on performance it might be the amount of boost your engine see .. therefore a boost gauge may offer some insight about your turbo and engine..

 

[1973Guppie]

also, if I do decide to install a boost guage, what amount of boost should I be seeing with a 3.2 guage and a 2.8 guage?

 

[lastresort576]

also, if I do decide to install a boost guage, what amount of boost should I be seeing with a 3.2 guage and a 2.8 guage?

this is why you need a basline of each and to monitor it closely for a while. Each compressors ability to make x amount of boost is going to depend upon the condition that it's in IMO.

I trust the hard facts more than 'here say' and it's not difficult to hook up a boost gauge.
For example every where I had read, the internal wastegate on a DSM t25 turbo is supposed to be around 8psi. My gauge and another were reading out at 15psi. This was good to know because it explained why my tune wasn't right.

 

[1973Guppie]

any combo boost / afr guages that guys reccomend? would like to run just one guage if possible. I found one AEM one but it is $$$$

 

[1973Guppie]

this is why you need a basline of each and to monitor it closely for a while. Each compressors ability to make x amount of boost is going to depend upon the condition that it's in IMO.

I trust the hard facts more than 'here say' and it's not difficult to hook up a boost gauge.
For example every where I had read, the internal wastegate on a DSM t25 turbo is supposed to be around 8psi. My gauge and another were reading out at 15psi. This was good to know because it explained why my tune wasn't right.

Yes but you are talking turbo and "tuning". I don't plan to tune anything. I am leaving all settings stock, not advancing timing, etc.