MrSuzuki

This may be one of the easiest questions to answer...but since I don't know the answer:

How direct is the correlation between the amount of air a particular air filter system (Scotty, AFE, Stock) can flow, and the resultant EGT?

For example, if anyone would compare a stock air filter system to a Scotty air filter system on a modified truck...all things kept the same for testing...the conclusion would be, lower EGT's with the Scotty.

Therefore, if a guy chooses an air filter system, which shows the lowest EGT's for a given test...are they then choosing an air filter system which FLOWS the most air? Or is there another variable involved, which could influence your EGT's, with regards to an air filter system? or is it strictly dependant upon air flow?

chaos24valve

I am probably wrong, but from what i have managed to learn on here; the more air that you have in your engine, the less fuel it will have to burn in the resulting reaction?....Tons of the guys on here can answer this question better than me, but that is my conclusion.

Rare1

Correlation is not the way to describe it. A good description is "sufficient". If you don't have sufficent air you can't burn all your fuel. Please don't believe a CTD automatically needs a BHAF or similar. The stock air box and paper filter will supply more than enough air for a stock engine. When you install your mods and try to burn more than stock amount of fuel you will need more air, possibly surpassing the capability of the stock filter. Here's how you test it: After each BOMB take a timed accelleration run over a measured distance you have timed and recorded EGTs before. A passenger with stopwatch is a good idea, also the same GVW. Keep all these timed runs and EGTs recorded in a booklet you keep in your glove compartment. Then remove your paper filter and leave the top off the filter box. No restriction, and no filter so do this on a clean road on a clean day. Take another run, no filter. If the second run is quicker or lower EGT than the first run you have benefitted from increased air delivery. You need a bigger filter.

For those who tune for towing, like me, the test is different. With your rig loaded drive up a long hill at constant normal cruising speed. The hill must be steep enough to really make your engine work. Note your EGT at the top of the hill. Turn around and do it again with your filter and box cover removed. Same constant speed, same gear. If you get lower EGT you need a bigger filter.

Of course if you need a bigger filter you might also need a bigger exhaust.

MrSuzuki

I am not trying to determine if I need a different air filter system, I am trying to determine if the EGT's correlate with the amount of air a particular system can flow.

Rare1...from what you described in your testing method...it does appear that as an EGT rises (under a given test), it is a result of the amount of air flow the engine is receiving. Simply because, test with filter = xx amount of air flow, and test with no filter = max. amount of air flow. Due mainly to the fact that there is no restriction of the air flow from the filter.

Bottom line/question...if I seek an air filter system that others have commonly reported to have lowered their EGT's...such as the Scotty II...will I have then found the air filter system that flows the most amount of air?

RowJ

Yes, Greatest drop in EGT's, per a given truck, has to be the system that flows the most number of O2 molecules....all other things being equal.
I word it this way to clear up any confusion about the effect of the air temperature....cooler, dense air having more O2 molecules, even though it may not produce as much boost pressure at the gauge.

RJ

AlpineRAM

Well I'd put it like this- the lowest EGTs you will find with a system that gets most air to the turbo- it doesn't necessarily mean that it has to have the best flowing filter- it can also work by using pressurized air from some part of the vehicle body, good piping etc.

AlpineRAM

TxDiesel007

I think of it this way

The more fuel u have to burn, or the more fuel u have coming out of the tailpipe, you need a larger turbo, and better airflow, I dont like what gale banks said when he said smoke is cool, but its wasted HP u can see, more (orovided its dense) air will help cool the EGT's and burn the fuel more efficiently

Tx