Turbo Kit v1.0 for Figgy's Insight

First test run data page 1 [ Click Here for more ]

Until there is time to post more information in an organized way, I will put bits and pieces here as they come up. Here are three snapshots of a test run to see what the MAP sensor is reading as maximum boost. It appears sometimes that the analog gauge may give boost readings that are not matching up to the MAP sensor boost readings. This happened at least once where the analog gauge indicated over 10 lbs of boost, but the MAP sensor did not agree and read lower. In theory we wanted the wastegate to be set to an absolute max of about 6 lbs of boost. What we ended up with was 7 lbs according to our initial test drives watching the analog boost gauge when we did test driving at Midnight after we did final adjustments to the wastegate actuator to lower max boost to our target of around 6 lbs. We figured 7 lbs was fine - this was the max boost the analog gauge recorded for full throttle in 2nd gear on the flats.

When in 3rd or 4th gears, full throttle gives boost levels of about 4 to 5 lbs according to the analog gauge. I have not recorded MAP sensor data for those tests yet. When in 2nd on the flat with full throttle the analog gauge on our first test runs went smoothly up to 7 lbs and then we hit redline and downshifted. This was reproducible behavior at Midnight on the flats. Back here in Bay Area a week later, accelerating onto the freeway in 2nd with full throttle, boost on the analog gauge went over 10 lbs and I backed off the throttle at once. I was recording the MAP sensor data and it maxed out at about 47 inHg (which is 23.1 lbs absolute, or 8.4 lbs of boost over atmospheric). This was more than 7, but it wasn't nearly 10 or 11 as the analog gauge implied.

I am figuring that the MAP sensor is probably more accurate than the analog gauge, and that perhaps the analog gauge spikes or dips as the pressure or vacuum travels up and down the small tube that connects it into the air intake system. In any case, without a passenger, so without being able to read the boost gauge during the run, I did a run recording MAP sensor data for test of full throttle in 2nd gear up a mild hill. It was 2 am, with no cars for miles, so I could slow down and speed up for each cycle of acceleration and boost. I recorded the run data on a Palm, so graphing capacity is limited. I can't post the raw data either.

While I don't drive this way (by flooring the throttle until redline before shifting), for the test I wanted to know what the real maximum boost levels recorded by the MAP sensor were under those conditions. I want to know what our real max levels are in the lower gear (2nd) where we can get higher boost levels vs. 3rd or 4th and I want to know that I can accelerate hard this way without having an error either of overboost or a MAP sensor CEL error which is dangerous to get if you are accelerating for a reason - as the IMA goes off and the car drops to a 'limp home' safe mode which causes it to lurch and slow immediately and lose acceleration. Not good if you are giving it full throttle because a semi is about to run you over!

Fig. 1

In this plot in Fig. 1 with the vertical axis all the way down to 0 inHg you can see the zero boost level (vacuum) with throttle closed, followed by gradual increase in boost and smooth increase in engine rpm after I apply throttle (full throttle). You can see that I am shifting for these two runs at about 5500 rpm. Actually, I think on many of these I did not shift, but just let off the throttle to slow down to repeat again. I am watching the engine speed, and don't have someone to watch the analog boost gauge, so I do not know what it is reading. You can see pretty clearly that boost is reaching a plateau well before I max out RPM. In Fig. 1 it is kind of hard to see what the max boost level is, but it is around 47 in Hg. See the conversion table at the bottom of the page to convert the MAP inHg to boost in lbs.

Fig. 2

In this plot in Fig. 2 the max vertical axis is 47.2 inHg which corresponds to 8.5 lbs of boost. You can see that either the compressor bypass valve or the wastegate is keeping boost at a little bit below this level. The BOV installed now is in fact a Bosch compressor bypass valve and there are folks on-line who claim that it leaks at 9 lbs of boost - so it is possible that this plateau at around 8.5 lbs of boost is because the Bosch valve is beginning to vent vs. the wastegate controlling the max boost level. It depends upon how much you trust the Bosch to hold pressure. In any case, the collective system is capping boost at this level as engine RPM is continuing to rise (and exhaust pressure presumably) during the time when the boost level starts to level off just before upshifting (or letting up on the gas). Most of the time I just let off the throttle, and slowed down to run up again - rather than upshifting.

Fig. 3

This Fig. 3 plot shows more of the same, where you can see from the three tests the same plateau at around 8.5 lbs of boost. The first two cycles I drop off the throttle a little early, and boost peaks a bit shy of the third cycle peak where RPM hits over 5500. In the third cycle recorded here again there is the clear plateau (which is around 47 inHg) which is about 8.5 lbs of boost.

Additional Data from the Test Drive

The following table records data from the same drive as the above graphs. The Palm software will not graph more than two data streams at a time, so I can't show it graphicaly. The entries where the note says 'end' are the last data points at the end of a cycle where the throttle is just closed and the MAP is still high because it is at the instant the throttle is closing and there is a little lag in how the software is reading the data streams. The 'a', 'b', 'c' notes indicated that these are data points from the same cycle. You can see for these tests that the boost level is reaching a plateau of around 47 inHg (+/- a tad) which corresponds to a boost level of about 8.4 lbs of boost. In each of the abc cycle trios you can see that while RPMs go from about 4900 or 5000 to over 5000 (up to 5516 in the first cycle) the boost level does not increase so we are reaching max boost and holding it. Max boost seems to be hit at around 5000 rpm under the conditions of this test run.

Run Data Table

Speed MPH 2nd RPM Throttle POS inHg MAP note
49 4401 90.6 39.4
55 4610 9.8 40.8 _end
52 4421 90.6 41.7
60 5015 9.8 47.4 _end
52 4357 90.6 42.9
54 4808 90.6 44.7
60 5051 90.6 47.1 a
60 5308 90.6 46.8 b
65 5516 9.8 47.1 c_end
56 4963 90.6 46.2 a
61 5184 90.6 46.8 b
64 5444 90.6 46.8 c
58 4912 89.8 46.2 a
60 5105 86.2 46.8 b
57 5028 90.6 46.5 c

Converting MAP sensor readings to Boost levels

The MAP sensor records absolute pressures, and the boost gauge reads pressures relative to atmospheric, so in order to interpret the MAP sensor readings in terms of boost you need to convert the MAP reading to PSI and then subtract atmospheric (c. 14.7 PSI) to get the boost level. This table does this conversion for the area of interest.

Conversion table MAP inHg to lb Boost

MAP inHg lb Boost
30 0.0
31 0.5
32 1.0
33 1.5
34 2.0
35 2.5
36 3.0
37 3.5
38 4.0
39 4.5
40 5.0
41 5.4
42 5.9
43 6.4
44 6.9
45 7.4
46 7.9
47 8.4
48 8.9

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