HUGE intrcooler & lag?

[1FASTKINGCAB]

I was at the junkyard today a spoted a '99 ford f350 W/ a intercooled power stroke I snached up the front mount I/C for $50 with a broken mounting ear but other than that it's in great shape. the only problem I see is that the thing is huge it's about 30" wide 24" tall & 23" thick it's crossflow I think that what you call it since it flow left to right, It also has huge 3" in/outs. just wondering if thist would cause alot of lag?

[Guest gprix1]

23" THICK!!!!!

[1FASTKINGCAB]

sory I forgot that the "minus" and "plus" butons no longer work on my POS keyboard. The I/C is a little more than 2 1/2" inches thick (2 TO 3" thick)

[awd92gsx]

That's probably a bit much...you might notice a little more lag, but nothing too serious.

 

What turbo are you running?

[Lockjaw]

Perhaps the better question is, will that thing fit in the front of you Nissan?

[1FASTKINGCAB]

awd92gsx: I don't know what turbo i'm going touse just yet though I'm 90% sure I'll use a good old Garret T3.

 

lockjaw: Oh yeha it will fit, it fits great. But don't thik there is any more room for the A/C to go back in though. It's a tight fit the inlet & outlet at a 90° angle to the I/C so the wrap perfectly around my radiator and rin into the engine bay. on;y about 60% of the I/C will be open to air flow due to the truck front bumper but it think it will work out ok.

 

I'm just woried about lag cause I've never realy driven a turbo car more than a few feet and don't know what to expect.

[fl327]

i have that same intercooler in the garage, ive heard they dont flow that well from people, but with a t3 i think you will have more than enough cfm. i tired to fit it to a z, no way no how will that thing fit in there without some serious mods, its way bigger than the radiator from every demension. what size piping are you gonna go with, if you go 3" from the inlets you will notice the lag with your t3, 2.5 inch or so should be good, or go with 3"-AND DUMP IT!

[Guest Zcarsmakemyheadhurt]

How thick is it really?? I think those are only 2.50 inches if that,thats OK for a T3 but I would shorten the diameter of those inlet and outlet to 2.25inch and use 2.25inch pipe. Your gonna have a big pressure loss with anything more I belive.

[Lockjaw]

Ok it fits. Here is the other issue I have. I am not a fan of any stock intercooler. They are basically designed to operate with a specific set of parameters, and generally, the highest performance is not one of them.

 

I also don't think with a T3 that you need intercooer lines any larger than Alex said, which is 2.25 inches.

 

What about this one? http://www.roadraceengineering.com/parts/icpics/18inchic-sameside.jpg It is 475, and will do everything you need with your setup.

 

I would find a way to make my AC work. No way around that one. Unless you don't drive the vehicle much.

[TimZ]

Originally posted by Zcarsmakemyheadhurt:

How thick is it really?? I think those are only 2.50 inches if that,thats OK for a T3 but I would shorten the diameter of those inlet and outlet to 2.25inch and use 2.25inch pipe. Your gonna have a big pressure loss with anything more I belive.

Pressure loss from a larger pipe? Why?

 

I'll buy possibly a very slight increase in lag due to the larger system volume, but the 2.5" pipe should result in a lower pressure drop between the compressor outlet to the intake manifold.

[DAW]

I'm totally guessing here, but it seems like taking the wastegate signal from up close to the throttle plate might minimize the variances in pressure that may be inherent in such a large volume system, i.e., modulate wastegate by what pressures the engine actually "sees" vs what's going on right at the compressor. DAW

[SleeperZ]

Originally posted by DAW:

I'm totally guessing here, but it seems like taking the wastegate signal from up close to the throttle plate might minimize the variances in pressure that may be inherent in such a large volume system, i.e., modulate wastegate by what pressures the engine actually "sees" vs what's going on right at the compressor. DAW

With larger volumes of air, you will see less pressure drops through the system, as pressure drops will occur with restrictions. However, locating the wastegate signal near the throttle body may not work as well as you might think -- for one thing, the wastegate doesn't care what pressure at which it regulates the boost, the main thing is it should be STABLE. The user can adjust the boost so the engine sees the desired boost level. If you try to regulate the wastegate to manifold pressure with a large volume of air (intercooler and piping) in between, you may get unstable boost, as there is a lag associated with the boost signal. The wastegate will react to pressure changes after the intercooler, and the delay through the piping will cause the wastegate to overshoot the mark. You may see boost spikes, in other words.

[DAW]

I dunno. I'm not talking about using manifold pressure though, just a signal from the outlet of the intercooler, closer to the throttle plate, rather than before all the intercooler plumbing and hardware (including BOV). It seems like all that compressable/expandable volume of air goes unmonitored and could result in boost spikes/holes. It's run this way stock on my Starion and works well; but it's right off the compressor on the L28ET and it's good too, but neither has a huge intercooler. DAW

[DAW]

I dunno. I'm not talking about using manifold pressure though, just a signal from the outlet of the intercooler, closer to the throttle plate, rather than before all the intercooler plumbing and hardware (including BOV). It seems like all that compressable/expandable volume of air goes unmonitored and could result in boost spikes/holes. It's run this way stock on my Starion and works well; but it's right off the compressor on the L28ET and it's good too, but neither has a huge intercooler. DAW

[awd92gsx]

Actually, zcarsmakesmyhead hurt is right,

 

Having too big of piping WILL cause a pressure drop, sort of...

 

Remember, before you can pressurize the intake manifold, you have to pressurize the I/C piping and FMIC...

 

I ran this FMIC on my DSM for a couple of years and loved it, especially for the cost...

 

http://www.turbochargers.com/currentspecials/FMIC.htm

 

When I ran my Frank 4 I was forced to get the boost signal directly off the intake manifold. Using the Profec B I never had any kind of boost spike...the only downside is that if you are in high load/low throttle situations your turbo may be spooling unnecessarily...

[SleeperZ]

Originally posted by awd92gsx:

Actually, zcarsmakesmyhead hurt is right,

 

Having too big of piping WILL cause a pressure drop, sort of...

 

Remember, before you can pressurize the intake manifold, you have to pressurize the I/C piping and FMIC...

 

I ran this FMIC on my DSM for a couple of years and loved it, especially for the cost...

 

http://www.turbochargers.com/currentspecials/FMIC.htm

 

When I ran my Frank 4 I was forced to get the boost signal directly off the intake manifold. Using the Profec B I never had any kind of boost spike...the only downside is that if you are in high load/low throttle situations your turbo may be spooling unnecessarily...

Huh? You are going to have a hard time convincing me about that...pressure drops are caused by more airflow than the piping or IC tubes can handle (restrictions!). Tubes that are too big may cause the airflow to slow enough to get a lag, or create a poor throttle response, but not a pressure drop.

 

You may not run into boost control loop problems with an electronic boost controller - it has circuitry that can handle a slow boost signal. As a matter of fact, the Profec B has a reference signal off the manifold already - I've no doubt it could take the boost signal off the intercooler exit without any trouble...a MBC, now that may be a different story.

[awd92gsx]

You're absolutely correct, but, you're thinking about only the piping. You won't have pressure drop across the piping, but, you will have a pressure loss if the piping is much larger than the outlet of the turbo.

 

Imagine having an air hose with 90psi in it. Now, imagine having a fitting that dumps into a garbage can. Although you will have 90psi in the hose, you will have much less pressure in the garbage can UNTIL there is enough air there to equalize the pressures.

 

Having too big of an intercooler and piping will cause a *temporary* pressure loss between the turbine outlet and the throttle body. Now, with a high enough CFM turbo this will hardly be noticeable, but the T3 is, in my opinion, not a high flowing enough turbo to warrant having all of that extra intake volume...now, if it was a T04E or something like that, that'd be different...

 

So, in effect, what I'm saying is that both of you are right. There will not be as much pressure loss across the FMIC and piping, but it will take longer to pressurize the FMIC and piping. You want as little piping and FMIC as possible while still having the cooling effect... (hence the reason for water/air IC's)

 

One of the biggest problems people with MBC's face is that they oftentimes run too much vaccuum line and run the wrong size of vacuum lines going to their boost controller. I ran an MBC for awhile and found that I could minimize boost spike by relocating my MBC and running silicone lines (which didn't expand as much under pressure, every little bit helps)...of course, the design and build of the MBC has alot to do with it, too. I did, however, have an external wastegate...

[1FASTKINGCAB]

So would it be a bad idea to run this I/C? I only got it because it was cheap and it's the bigest FMIC that I think I'm going to find in a junk yard. I wasn't thinking about he effects of dumping a 2.5" pipe into a 3.5" pipe and then into a 2.75" pipe, But I don't just want to run a 2.75" pipe straight to my engine W/O a I/C of some kind

 

P.S. what's the diff.? "Pressure drop" and "Lag"? If a turbo outlet is say 2" and one used 4" pipe it would take a moment for the turbo to fill the extra area in the pipe. that would be lag right? so if one ran 2" pipe from the same turbo to a 4" section of pipe and back to 2" just before the TB wouldn't that cause lag? It would take a moment to fill the 4" section but after it's full I would think the whole system would have the same pressure across the board. or am I way wrong? or dose lag also involve the exhaust gas pressure?

 

Thanks,

Tom D

[awd92gsx]

There are so many things that affect lag, it's not even funny.

 

The include, but are not limited to, compression ratio, turbo size, clip, intercooler sizing, I/C pipe sizing, wastegate control, wastegate design, proper/improper air/fuel ratios, timing, manifold design, camshaft selection...just to name a few..

 

I think a good sized intercooler for the T3 would be something closer to a Starion sized FMIC, or something like the 18" wide Griffen...

 

That FMIC that you got is a little big for the T3, IMHO...however...if I were you, I'd stick it on, stick your turbo on, and go have fun! Trust me, you won't notice the lag. You'll be too busy wiping trying to wipe the grin off of your face!!

 

Now, if you were running a T04E, the FMIC you have would be perfect...but...a T04E will lag more than your T3...but, there's quite a bit of misunderstanding when it comes to bigger turbos and more lag.

 

Here's a good example...

 

When I owned my 1992 Mitsubishi Eclipse GSX it came stock with a Td05h-14B(stock M/T turbo), which is roughly the same size as your T3. I ran 17psi with the 14B.

 

Later on down the road, I upgraded to a Frank 4, which is closer in size to a T04E (it even uses a T04E compressor wheel in a reverse 20G housing). When I bolted it on I left it at my wastegates lowest boost setting, which was about 9psi (on a Deltagate).

 

Eventually I ended up running 19psi with the Frank 4...but here's the thing...

 

If I hooked up a video camera to watch the boost guage and the tach, you'd probably notice that the boost guage went up slower with the Frank 4 than it did with the 14B...but...if you drove it, you'd feel that the Frank 4 was faster throughout almost the entire powerband (but at high rpm's especially)

 

The F4 felt stronger at 9psi than my 14B did at

[SleeperZ]

Originally posted by awd92gsx:

You're absolutely correct, but, you're thinking about only the piping. You won't have pressure drop across the piping, but, you will have a pressure loss if the piping is much larger than the outlet of the turbo.

 

Imagine having an air hose with 90psi in it. Now, imagine having a fitting that dumps into a garbage can. Although you will have 90psi in the hose, you will have much less pressure in the garbage can UNTIL there is enough air there to equalize the pressures.

 

Having too big of an intercooler and piping will cause a *temporary* pressure loss between the turbine outlet and the throttle body. Now, with a high enough CFM turbo this will hardly be noticeable, but the T3 is, in my opinion, not a high flowing enough turbo to warrant having all of that extra intake volume...now, if it was a T04E or something like that, that'd be different...

 

So, in effect, what I'm saying is that both of you are right. There will not be as much pressure loss across the FMIC and piping, but it will take longer to pressurize the FMIC and piping. You want as little piping and FMIC as possible while still having the cooling effect... (hence the reason for water/air IC's)

I understand what you are saying now, however I call that "lag," not pressure drop. It seems to me there really is no pressure even at the turbo, until the volume is filled at boost pressure, hence no pressure "drop".