I am trying to get my tune sorted and recal sometime back stumbling across so info stating that you could lean the tune out in order to help build boost quicker. My turbo is a little large for my current combo becuse I sized it according to future plans. I tried a web search but get confliction info. FYI this is a mild street car-mustang with 302 and 76mm. No trans brake and on footbrake the conveetors goes 2000-2200.
Thanks for you help!

 

I have heard of less timing but don't know the ins and outs. I would think a little rich would help. I think that would get you a little more exhaust heat.

 

I am assuming you are running a automatic. With an auto you run "Lean and Mean" lean and more timing. If you had a manual you run rich and low timing. This is conflicting as with the automatic you want to put as much power into the converter and hope to get the turbo on the converter.

With a manual you can spool the turbo with unburnt fuel in the exhaust stream, via a rich set up with low timing and a two step.

I had a setup that was pig rich with normal timing spool a large turbo on a trans brake very quickly. It also fouled plugs so it did not work in the long run but it did spool quickly.

 

OK. That explains why I was finding what appeared to be conflicitng info. My tune is set up lean around the 2000 rpm range so I will leave it for now and see.

Thanks!

 

Lets talk real numbers here. Lean and rich mean different things to different people. The neither one really works.... the correct amount of A/F for the load you are in spools the turbo faster.

When my car was tuned at 10:1 a long time ago, it wouldn't spool at all even on the break and a 5000 rpm converter. I could be on the break for 10 min and only get 5psi

When the A/F ratio was correct I could get 25psi in 1.5sec.

This also isn't just a tuning problem, it can be cam, converter, backpressure or exhaust housing/wheel.

 

Going to shed any light on your correct A/F? Since you are looking to talk about real numbers... I'm sure the OP is interested.

 

When I suggested, I assumed a correct build and proper running engine was to start with..

Turbonova, how did you tune your car to 10:1 af? I though the bottom reading on a wb was 10:1.

Could you have been richer? 10:1 is pig rich to the point the engine might not even be running right.

 

Most widebands will read lower than 10:1 but some of the cheaper stuff stops showing once you get to 10:1. When I first started tuning and got help from someone else he though we should be at 10:1 and that really didn't work well for spooling the car.

If you are tuning the car below where it makes boost.... isn't it in the N/A area of the map? So why would we tune it differently than we would a N/A engine? At that point the engine does not know that is has boost coming on later.

 

Makes sense.
I wasn't arguing, just learning!

 

Most of the time someone either has the wrong converter, bad tuning rich or lean or too large of a turbo to make it spool quickly.

As you move from 10:1 towards 13s, maybe 12s you will find that the engine starts to accelerate quicker and in turn the engine will make more power and also spool quicker.

 

I do agree with what tune makes the most power should build boost the fastest with a automatic. However this has not been my experience with a large turbo. My 7.5:1 compression 306, and a super rich tune, (wasn't even firing on all cylinders) spooled much faster than after I had the car tuned. There is something to having fuel burn in the exhaust(rich) or high EGT(lean), compared to a stochimetric mixture.

Here is the video of the super rich 306 spooling a 96mm turbine.

http://www.streetfire.net/video/mikes-turbo-mustang-testing-transbrake_113133.htm

 

No one ever said stochimetric... that isn't where the engine makes best power. In fact most modified domestic V8s don't even like to run there.

If you have an engine that isn't running on all cylinders then you can't really compare that, since it is misfiring into the exhaust and will effect spool time.

High EGTs will help spool but usually on a domestic V8 you will lose too much power from the engine when you retard the timing.

Again converter is a BIG deal. And everyone has their own ideas on a tight or loose converter.

 

Why cant you count a engine misfiring into the equation? What is a two and three step used for?

High EGTs can be obtained in more than one way... Timing does not need to be retarded for high EGT's, A:F ratio alone will do it.

 

Just from my experiance when just cruising i can get it to go off the scale lean and start running like shit but i can hear the turbo instantly start spooling and if i mat it after that there is zero lag

now if im cruising and af is in the 14-15 range and i mat it takes a second for the turbo to spool then it wil go

again just my experiance so far which is limited

 

Sure, engine misfiring is one way to help spool the turbo. But the question was rich or lean and not how do I spool my turbo.

A/F both lean or rich will cause high egt but again the engine will lose power when you get to that point. This will also hurt spool time.

 

egt is highest at stoich as you lean or enrich you cool down

most engines accelerate best at around .85 lambda below peak tq

 

Not really, EGT changes with Timing more than it does with fuel. When you have too much fuel it will burn into the exhaust and show high EGT, When it is lean you will see high EGT. As you move timing you can get it to cool down or heat up even if the mixture is lean or rich. There is way more to looking at EGT than your post.

 

since it was in regard to fueling i was referring to fuel, guess i should have said with no timing adjustment just to clarify

with timing static stoich can be found with an egt by finding the hottest point


or am i wrong?