Front Mount *Lag*

[bruce]

In reference to this Intercooler selection stuff, I thought I'd toss this out there. There's been allegations of too much Intercooler being a **bad** thing, or why bother with such a large one. In the Intercooler Selection thread there are some data logs, showing actual MATs from datalogging. So I kind of beat the topic to death about temps., in that one. Thought I'd post a little data about this alleged *lag* problem.

Let's see starting to make boost at 1,800 RPM,
206/206, TA-62, stock converter, 60 PPH injectors.
Even my BBC truck has to get off idle to start making any power.

Run Mph Rpm Map VE% Tps CTS MAT Sa Rt sPW AFR rrWB
19:06 0 1825 101 90 59 168 95 27 0 3.63 12.5 10.7
19:06 0 2000 104 90 78 168 95 27 0 3.75 12.5 10.1
19:06 0 2025 105 88 95 168 95 28 0 3.78 12.5 10.3
19:06 3 2075 106 87 100 168 95 28 0 3.75 12.5 10.5
19:06 3 2125 108 86 100 168 95 28 0 3.69 12.5 10.3
19:06 3 2175 110 84 100 168 95 28 0 3.72 12.5 10.8

*The *excessive* richness is from the AE.

While some really big turbos, and loose converters, can be slow, a *healthy* street car, it's only a *problem*, if you think it's supposed to be like nitrous. Most any engine, has to get into it's operating range to start making power. Some power bands, yes, are wider then others, but you can only use so much off idle anyway. At the lower rpms, the firing pusations are further apart, so the shock loads to alot of components, are worse.

Needless to say the proper tune also comes into play in a huge way. You may want to note the amount of resolution in these table, and that in particular the VE has some drastic changes, well that's what happens when you start getting the tune correct.
Looking real close at both tables, you'll see how the timing and fuel play together real nice. And while most people tend to think of boost starting at 100 K/Pa, it doesn't really happen that way. On something like a GN in N/A mode, the darned thing probably'd never get over 90 K/Pa. So it's at that stage of where the turbo is starting to kick in, since the engine is breathing better then it possibly could in N/A mode. It's kind of splitting hairs, but understanding that makes for no Tip-In preignition, and a host of other illnesses, ie crazy amounts of AE, too much timing, etc, etc.

I've included the timing, and VE table from that *run*. To get degrees of timing, multi by .351. To get VE in %, multi the VE values by .351.

If the tables don't look *right* or *familiar*, it's because this is my modified Syclone code.

NormalTimingTbl
TABLE Main Spark Advance
Map:20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

68,68,68,68,77,74,74,74,71,71,71,68,68,68,60,60,60 ; 600
68,68,68,77,77,74,74,74,71,71,68,68,68,68,60,60,60 ; 800
68,68,68,77,77,84,84,84,81,81,75,72,72,68,65,65,63 ; 1000
35,35,68,68,81,99,99,99,93,90,81,78,75,75,68,65,65 ; 1200
35,35,35,74,89,109,109,109,109,109,99,90,81,75,75,72,72 ; 1400
35,35,35,74,99,112,112,112,112,112,106,93,84,81,78,78,78 ; 1600
35,35,35,74,99,120,120,120,120,120,120,99,96,93,90,90,90 ; 2000

NormalVeTbl
; Base Pulse VE vs RPM And MAP
Map: 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 ;
20, 30,100,115,125,125,130,134,134,138,145,145,150,155, 155,155; 600
20,30,100,115,125,125,125,134,134,138,145,150,155,155,165, 165 ; 800
20,30, 60, 75,115,130,133,135,155,175,190,210,210,210,210, 210; 1000
20,30,35,45,105,135,140,140,160,215,215,220,220,220,215, 215; 1200
20,30,30,45,95,135,155,170,180,180,215,225,225,225,220, 220; 1400
20,30,30,45,95,135,165,175,185,190,215,240,235,235,230, 225; 1600
20,30,30,45,95,135,165,175,185,185,195,235,220,205,210, 200; 2000

When your done reading it, try it again in 20 mins, and see what you see.

 

[bruce]

Forgot to mention, I'm using one of Jason's new Boost controllers.

http://www.rjcracing.com/RJC_Buick_Products/BoostC/boostc.html

 

[Jerryl]

Good thread on current debates .........

 

[VadersV6]

It takes alot of air volume to fill up 20+ psi of air in the front mount IC and all the huge plumbing that usually comes with them. I think most FMIC's for our cars are oversized. First you have to wait for the turbo to spool. Then you have to fill up all that volume, and THEN pressurize it....now its ready to fill the cylinders. An efficient small/medium sized IC with 2.5" tubes would be perfect, and the lag wouldnt be an issue, especially if you slap on a boost controller from RJC or whoever. People like to see huge pipes on their cars, but theres a price to be paid. Keep things small to improve velocity and response. No matter what the size is, if you're within 30 degrees of ambient, and have a 1psi drop, you've done pretty well. There are pretty compact IC's that can fit this bill.

 

[turbopaul]

WOW..an old worthless post brought back to life:frown:

Paul

 

[DCVING 6]

WOW..an old worthless post brought back to life:frown:

Paul

Yea, actual data is so *worthless*. Why don't we get a bunch of hear-say in the thread to make is a quality post.

 

[8AV8]

WOW..an old worthless post brought back to life:frown:

Paul

Did you read....better yet, UNDERSTAND what Bruce is talking about?

 

[turbopaul]

No, I do not understand......maybe someone could put all this data to a graph, and show the diference between a large IC and a small IC in terms of lag. I would appreciate it. Thanks!

Paul

 

[Jerryl]

Pretty sad that someone went through ALL this effort of collecting some actual data, post/share it, and some do not even have the decency to thank the person for “just sharing”? What about finding something positive to say? Sad. :frown:
Right or wrong, VERY FEW will record and share data. No wonder people don't share their experiences. Reasons for sharing detailed data may vary from:

1. Inability to design an experiment
2. Inability to record
3. Inability to understand
4. Not wanting to share, because .......... (Fill in your own blanks)
5. Scared to get ridiculed by others.

 

[gnjones231]

I used to post data many years ago, but it didn't go over very well. I was met with what seemed to be blank stares by most, and a few people seemed to be offended by it for what ever reason. So it seemed like a waste of my time so I quit posting. Being that this thread is about IC's , here is data I took on my GN some 15 years ago. See if it makes any sense to you.

 

[S2V6RACER]

Yea, actual data is so *worthless*. Why don't we get a bunch of hear-say in the thread to make is a quality post.

Edited

 

[Jerryl]

I used to post data many years ago, but it didn't go over very well. I was met with what seemed to be blank stares by most, and a few people seemed to be offended by it for what ever reason. So it seemed like a waste of my time so I quit posting. Being that this thread is about IC's , here is data I took on my GN some 15 years ago. See if it makes any sense to you.

WOW, interesting!
THAT my friend speaks volumes!
What was the combo and which IC and conditions?

 

[TurboBob]

It takes alot of air volume to fill up 20+ psi of air in the front mount IC and all the huge plumbing that usually comes with them. I think most FMIC's for our cars are oversized. First you have to wait for the turbo to spool. Then you have to fill up all that volume, and THEN pressurize it....now its ready to fill the cylinders. An efficient small/medium sized IC with 2.5" tubes would be perfect, and the lag wouldnt be an issue, especially if you slap on a boost controller from RJC or whoever. People like to see huge pipes on their cars, but theres a price to be paid. Keep things small to improve velocity and response. No matter what the size is, if you're within 30 degrees of ambient, and have a 1psi drop, you've done pretty well. There are pretty compact IC's that can fit this bill.

Additionally, on MAF style systems the extra airflow from filling the intercooler and pipe volume causes a rich condition during spooling. The extra richness slows spooling.

Speed Density does not have this issue. (the MAF issue)


Bob

 

[turbo buicks]

Yea, actual data is so *worthless*. Why don't we get a bunch of hear-say in the thread to make is a quality post.

hahaha!

 

[gnjones231]

Jerryl, This is the stock IC. This data was taken almost 15 yeas ago, so I don't remember some particulars. But most likely it was stock boost, a fully warmed up engine, data taken on the street, most likely started from a dead idle.

Ha! I found this....the turbo fart

 

[SHADOWII]

Good work...

fellows!!!:biggrin: That's a good representation of our community! Thanks!

 

[S2V6RACER]

Jerryl, This is the stock IC. This data was taken almost 15 yeas ago, so I don't remember some particulars. But most likely it was stock boost, a fully warmed up engine, data taken on the street, most likely started from a dead idle.

Ha! I found this....the turbo fart

This is a nice job you did. I log the same parameters and store it in my Racepak V-300 logger. There are separate math channels in the V-300 you can program and take the raw data from the channels you choose and I could come up with the percentages. I'll work on that. I like it.

I also have a temp probe in front of the I/C so there is no doubt what the temp of the air was at the time you made your run.


I log: Ambient air temp, turbo out PSI, Turbo out Temp, MAP PSI, I/C outlet temp, MAT(In the plenum). We have already confirmed the Garrett cores ratings are accurate with the multiple tests we did on that unit last year(custom piece). Anybody who looked at my car has seen the probes. We began tests on another vendors unit, but ran out of time (mechanical problem at end of year) and I am not going to make any comments on that unit until I get repeatable data.


We will be installing the turbo shaft RPM sensor (Bigstuff 3) for next season so I will be able to start looking at the tuneup a little more in depth as far as spoolup goes. I can tell you that spark advance, and A/F can make a BIG difference in spoolup, I managed to get way more EGT in each cylinder with changes in starting line timing and A/F. I think the turbo shaft speed will be a good addition of data. The Racepak logs can be overlayed so I can take a exact point in time and see the differences the changes made. And will have a more exact idea of how larger/smaller intercoolers affect spoolup time but I suspect that the differences in combos will play a more major roll in spoolup between different intercoolers and I think it is a matter of splitting hairs.

 

[John Wilde]

We will be installing the turbo shaft RPM sensor (Bigstuff 3) for next season so I will be able to start looking at the tuneup a little more in depth as far as spoolup goes. I can tell you that spark advance, and A/F can make a BIG difference in spoolup, I managed to get way more EGT in each cylinder with changes in starting line timing and A/F. I think the turbo shaft speed will be a good addition of data. The Racepak logs can be overlayed so I can take a exact point in time and see the differences the changes made. And will have a more exact idea of how larger/smaller intercoolers affect spoolup time but I suspect that the differences in combos will play a more major roll in spoolup between different intercoolers and I think it is a matter of splitting hairs.

Ted,

Thanks for in advance for all the great information.
That race pack is an great piece!!!