Wednesday, April 13, 2005

more on MAP pressure drops and Intake tract

Yesterday night I went out with a friend of mine who is pretty much responsible for me getting into cars at all. As the matter of fact, my '99 Formula used to be his. This time around, he's got a '01 formula M6 with zero options, making it a very light (read: quick!) car. He has very basic mods, Lid, Fram air filter, and SLP Loudmouth. So I decided to see how healthy his car was (it was _very_ healthy, if 'comparative driving' is a measurement is worth anything ;) ).

Turned out his VE is a bit out of whack, as well as his MAF. With his crazy driving, we gathered enough data that in an hour we had both of them inline, along with a slightly better PE settings. We left timing alone for this time, as it was getting late and I had to get home.

But in the process of scoring lots of data, I managed to get his MAPvsRPM data, as per earlier post about intake restrictions.

So now i got 3 sets of data (my z06 cammed car, OtE's stock cam, and Camaroguy's TR224) they both have FRAM filters and stock MAF, while I got K&N and Granatelli MAF. I graphed out 2 scenarios for each car. One is a graph of MAPvsRPM for all data with 90%+ of throttle, and the other graph is 'top 400' samples of biggest MAP values.

OtE's stock cammed car peaked at 99kPa in 2800-4400rpm
The same car would also get 95-96kPa above 5500rpm.

Camaroguy's TR224-112 cam'ed car would do 97-98kPa in 2700-4400rpm
The same car would get only 90-95kPa above 5500rpm

My car (z06 cam+LS6 intake) peaked at 98-99kPa from 2000-4400rpm , (second graph)
This setup would get 94-97kPa above 5500rpm, (second graph)

The 3 cars push different amount of air (from the tiny 01cam through my z06 to 224/.563) they all have different MAF's, lids, filters, and mufflers.
My car seems to have the smallest drop in MAP at higher rpm (smallest bottleneck, I guess bigger MAF and smooth bellows do help a bit) or just the FRAM filters aren't as good as K&N.

There's enough variables here that I can't really make any conclusive comparisons, and there are few unexplained things (why does car with the smallest cam suck the most air?)

Tonight, I will hopefully have a chance to get another set of data for stock 01cam+Mac headers+LoudMouth, so I will probably put up more graphs.

any comments? anyone wants to send me more data?

4 Comments:

At 10:20 PM, April 14, 2005, Anonymous OtE said...

The map values are probably also being effected by weather conditions during the datalogging as well as the vehicle speed, as all of these cars have some form of ram air.

 
At 1:44 PM, April 16, 2005, Blogger Marcin said...

isn't MAF a FLOW sensor, not a density sensor? faster airflow would just cool it down more (isn't it called like convection or something?) asking for more voltage to keep the temperature of the heated element stable. MAF really oughtta be able to compensate for both speed and temperature, as one influences the other. how well it compensates for it, that's a whole different story.

besides, i ran my car the other day, and i was getting 100kPa easy. apparently the 'quality' of air counts for a lot more than i thought previously. so comparing these things from 3 different nights on 3 cars in 3 different places is absolutely worthless. oh well.

 
At 9:56 AM, April 18, 2005, Anonymous Anonymous said...

The drop on Camaroguy's MAP can be
explained by the cam; it lets the
motor "draw down" the manifold
pressure against the inlet tract
resistance more strongly than a
stock or a Z06 cam, having way more
lift & duration than either.

- jimmyblue

 
At 7:56 PM, May 12, 2006, Anonymous Anonymous said...

Log Baro Pressure and compare the difference between Baro and MAP. Thats what i have been doing. It has shown that i have claimed a small gain in Kpa with a bigger TB. Usually between 5000 and 6500rpm its about 1.7Kpa on average under Baro i have averaged over 100 on occasions. This is with a over radiator cai , BBK 80mm TB no filter and a baby cam 216 220 114 lsa ported heads 10.7:1 and 1.8 rockers with metal cats in the exhaust

 

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