I/C questions (UPDATE, more q's, I/C or better exhaust?)

[Guest bastaad525]

Was talking to a friend of mine who works at a speed shop yesterday, about getting this I/C installed. I was showing him what i wanted to do, how I was going to route the pipes and such. Basically I was going to try to emulate the kind of setup like Cygnus and a few other guys have done, here's the pic of his engine

 

 

now, my friend was saying that actually this setup would not be the best idea, that running the outlet/return pipe from the I/C back behind the radiator like this would significantly warm the charge back up before it get's to the TB. He's suggesting I go the opposite way, that is to route the outlet of the turbo in front of the engine and out the radiator support on the passenger side, and the outlet to go thru the driver side, a much shorter and more direct path back into the TB. This is gonna complicate things a bit for the install... adding the need for more bends, couplers and clamps. I'm just wondering... I mean a few guys here have done it this way so I gotta figure... is it really that bad as this guy says? The shop he works at is 90% camaros and mustangs so I dunno if his knowledge and experience apply the same here.

 

 

Also, and I know this is one of those more general questions that is best answered by "go to a dyno" but... as usual, money is tight, and once I get the I/C in I'm not gonna have enough dough left to go get it tuned right away. I figure that this I/C will cause the usual pressure drop of like 1-2psi... I'm using the grainger style boost controller... I'm planning on pretty much just leaving it alone. It' set to about 10psi right now, so should be around 8psi at the manifold after the install, right? Now, if I'm running a bit lean at 10psi as it is right now, obviously the I/C would make it much more lean at 10psi, but how about accounting for the pressure drop? If pressure drops down to 8psi, am I still going to be running as lean or even more so than I was at 10psi w/o the I/C? Do I need to worry about setting the boost even lower than that for safety until I get more fuel? If 10psi is generally considered safe on a non intercooled bone stock turbo motor, what is generally considered safe once you add the I/C, but everything else still stock? Do I need to just pull the boost controller out completely and run stock boost until I get more fuel?

 

 

Is power at 8psi with the I/C going to be comparable to power at 10psi w/o? more? less?

[Guest bastaad525]

That reminds me of a few other questions... this whole pressure drop thing makes me wonder...

 

 

For instance... since the AFM measures the air getting sucked in before everything else... if the turbo is sucking in 10psi of air, the AFM would be measuring that, right? So once it passes thru the I/C and drops some pressure, would the ECU now in effect being supplying more fuel than it's supposed to (10psi of fuel for 8psi of manifold pressure)?

 

Is there going to be a noticeable increase in lag?

 

What about BOV placement? Still best to just place it as close to the TB as possible?

 

I'm really trying to understand how the volume of the air, the pressure and the density of it changes as it heats up and cools down as well, how it relates to the actual psi of pressure felt in the manifold.

[Jersey]

525, you just need to install the darn IC! I know you have a lot of questions and sometimes there's no perfect answer for everyones different application. Just get that sucker installed and turn up the boost a bit!!! Here's a post from about a week or so ago with information about routing of the pipes - CLICKY I think the way Drax routed his pipes makes more sense to get the coolest possible air to the intake but if your running your filter out front through the rad support on the drivers side, it may be a bit easier the way Cygnus and i ran them.

[cygnusx1]

bast,

 

Take a look at my reply in thie neigboring thread page2:

 

http://hybridz.org/nuke/index.php?name=PNphpBB2&file=viewtopic&t=35183&postdays=0&postorder=asc&start=20

 

On the AFM thing, that thought crossed my mind when I was trying to get my car to run right and all it did was run rich! Well, a vacuum leak and too much FMU were the causes. Now it runs super sweet. I don't think that the AFM is "misreading" due to flow losses at all. Air in=Air consumed no matter what. Unless you have a leak.

[Sean73]

Cygnus makes good points. I have my IC installed the same way he does. The air traveling through the IC pipe on it's way back to the TB is not going to pick up much heat. For one, it's traveling a couple hundred feet per second. Number two, there is little surface area in the pipe compared to volume. Third, at high boost, hopefully you'll be going very fast, and underhood temps drop, and there's lot's of fresh air flowing through the engine compartment.

 

I feel that optimizing the placement of the IC as well as the length of pipes and number of bends would should be higher on the priority list., then worrying about the radiator.

[Guest bastaad525]

525, you just need to install the darn IC! I know you have a lot of questions and sometimes there's no perfect answer for everyones different application. Just get that sucker installed and turn up the boost a bit!!!

 

But I thought that was exactly what I did NOT want to do, at least at first. Remember, I don't have any way of supplying extra fuel just yet... no bigger injectors, no FPR. So I thought I might actually end up having to turn the boost DOWN at first, lest I would run WAY too lean with the intercooled air, and do more harm than good. All I remember was seeing someones dyno chart after adding an I/C and running 8psi on bone stock EFI and running pretty darn lean on top... so was figuring I'd have to stick to no more than 8psi after the I/C install as well... what do you guys think? If 9-10psi is ... well.. somewhat safe w/o an I/C (lean above 5000rpm with stock EFI, upgraded fuel pump), how much boost should I run after the I/C in in?

 

As for the return pipe crossing over the engine bay, common sense told me the difference should be minimal as well... it really shouldn't be able to heat up by much at all if the air is passing thru there that fast. I think this would really apply more to guys who are racing all the time or for a living even, where every little bit counts. So I'll probably stick with the original plan and just basically copy cygnus' routing and save myself some headache.

 

Another thing my friend at the speedshop suggested to me was actually to try to place the BOV closer to the I/C than to the TB.... well that sparked a whole other discussion, and so I wanted to get your guys' oppinion on that as well. For ease of routing (I recirc. my BOV), I'd like to keep it close to where it is now (bottom side of U bend of J-pipe)... I figure I should place it either on the return pipe right before the T/B, or... could I get away with putting it on the pipe between the turbo and I/C inlet?

 

I dunno why but I've always kinda wondered about putting the BOV closer to the TB anyways... seems to me it would make more sense to place it closer to the turbo itself, wouldn't it?

[231Z]

bastaad525 ,

 

Your piping seems most logical the way you have it. Remember the more bends, and particularly tight bends you add to the intercooler piping, you create more pressure drop and decrease the overall efficiency of the intercooler. The bends you have currently, are sweeping bends that will not cause as much drop in pressure.

 

BOV's are designed for the air that is trapped between the closed butterfly in the throttle body and the turbo. When a BOV is not used, as in the case of a Turbo Buick 3.8, you often here the shutter of the compressor wheel, "snorting". The BOV is designed to release that compressed air between the turbo and throttle body and designed to eliminate it from running back toward the turbo and cause that snorting. This will eventually cause your turbo to have shaft play or eat bearings.

 

Do not turn up the wick until you tune your car. Take time to get the appropriate injectors, FPR and wastegate. Get yourself good gauges and pay attention to them when driving.

 

Tyson

87 Buick T

87 GN 1600hp Sold

70 Z with 231 Turbo Buick

[Guest bastaad525]

Um... no offense here... but your post didn't make a lot of sense to me...

 

Your piping seems most logical the way you have it. Remember the more bends' date=' and particularly tight bends you add to the intercooler piping, you create more pressure drop and decrease the overall efficiency of the intercooler. The bends you have currently, are sweeping bends that will not cause as much drop in pressure.

[/quote']

 

Okay this one kinda made sense I guess... except for you saying "the way I have it"... I dont have it any way yet... that's the point, trying to figure out how it SHOULD be. But I think I get the gist... just do it the simpler way as is shown in that pic I posted. The other part that doesn't make sense, is that doing it the other way only adds two additional 45* bends, to the pipe between the I/C and TB... not sharp bends at all, I wouldn't think this would create any noticeable extra pressure drop... So I'm still kinda confused at this answer

 

BOV's are designed for the air that is trapped between the closed butterfly in the throttle body and the turbo. When a BOV is not used' date=' as in the case of a Turbo Buick 3.8, you often here the shutter of the compressor wheel, "snorting". The BOV is designed to release that compressed air between the turbo and throttle body and designed to eliminate it from running back toward the turbo and cause that snorting. This will eventually cause your turbo to have shaft play or eat bearings.

[/quote']

 

Um... dude I know what a BOV is for... did you read the post? I wasn't asking what a BOV does... rather, I was asking, where was the better place to move it to on the new pipes I'll be installing.

 

Do not turn up the wick until you tune your car. Take time to get the appropriate injectors' date=' FPR and wastegate. Get yourself good gauges and pay attention to them when driving.

[/quote']

 

Again... I'm not trying to offend you here at all... really I always appreciate it ANYTIME someone takes the time to reply to one of my posts... but this reply kind of seems like you didn't really read the post. I'm not talking about turning up the wick at all... actually the opposite... trying to figure out how much I should turn the wick DOWN to be safe until I get the money to hit the dyno. Sure I could just play it SUPER safe and drop the boost back down to stock... but that would suck. Why do that when many guys before me have gone down the same path I am trodding now, and have accumalated the experience to be able to say this is safe or that is not. So I figured.. you know, SOMEONE here must know what boost level is safe to run on stock EFI once an intercooler has been added.

[Guest bastaad525]

You know... I just had this pop into my head... so now I need yet more oppinions

 

 

Tallying up the cost of this I/C install, it has occured to me that it will be pretty close to the other big performance mod I've been NEEDING to do to my Z... 3" mandrel exhaust. Right now I"m running a bastardized exhaust that was the result of me running out of money doing this turbo swap.

 

I'm running the stock downpipe, and at the end of that is attached a 3" crush bent pipe, which runs from the DP to where the diff is (originally, this is where my exhaust dumped). From there, the rest of the pipe is 2.5" (this was done at a different place a month later, the guy who did the 3" was out of business by that point ) crush bent, with the two 90* bends, and then passed thru one of the 'bad' kind of glasspacks, the kinds with the little fins that stick up into the airflow.

 

Now... while my engine made a very healthy and very unexpected 200hp to the wheels with stock everything at 10psi... I can't help but think there's a bit of power corked up in this crappy exhaust. Maybe not as big of a leap as Jeff saw in his 280zxt (20+ hp), but still... enough to make a noticeable difference .

 

Would it be a better idea, at this point, to ditch the idea of installing the I/C and instead get a full 3" mandrel exhaust installed? The shop that the friend I mentioned originally in this post works at does this kind of thing... I'd have to check with him on cost but I'd expect it to be around $300... very similiar to what I'm expecting to pay for the I/C.

 

Both mods will net me extra power, I couldn't even GUESS which one would get me more... I have to assume that both mods would also help extend engine life, the I/C by cooling the intake charge, which I'm sure is way hotter than is really good at 10psi, and the exhaust I imagine would help by getting rid of lots of backpressure. To be honest I was going for the I/C just as much for the safety margin and less wear on the engine, as for the benefit of additional power.

 

Which one would be more beneficial, in each category (power, less wear on the engine)?? Which one would YOU guys do?

[wheelman]

Bastaad,

I don't have a turbo motor so take this for what it's worth but it seems to me that if you run non-IC and 10 PSI and it drops to 8 PSI when the IC is added it's still pulling the same amount of air through the engine. The pressure drop is because the IC cools the air charge after it leaves the turbo correct? If thats why the pressure drops then the air volume at 10 PSI non-IC will be the same as the air volume at 8 PSI with the IC. The volume of air moving into the engine dictates the amount of oxygen available to burn the fuel so your AF ratio shouldn't change much if at all.

 

Any of you turbo experts be sure to correct me on this if I'm wrong. What I'm trying to say is I think the amount of air moving into your engine will not change but it's density will because it's cooler. That is until you turn the boost back up, then you'll need to adjust everything to account for more air.

 

One thing to keep in mind though is that your boost controller is set to 10PSI so your turbo should spool up to that pressure even with the IC. The pressure drop is theoretical, in reality your waste gate will still allow the intake manifold to be pressurized to the pressure dictated by the boost control valve.

 

Wheelman

[Guest bastaad525]

One thing to keep in mind though is that your boost controller is set to 10PSI so your turbo should spool up to that pressure even with the IC. The pressure drop is theoretical' date=' in reality your waste gate will still allow the intake manifold to be pressurized to the pressure dictated by the boost control valve.

 

Wheelman[/quote']

 

Not in this case, I think. My wastegate line (and the boost controller that's inline with it) are connected at two points to the body of the turbo itself, and therefore sense the boost pressure right at the turbo, and wont compensate for any loss of pressure by the time that air enters the manifold. The wastegate is still seeing 10psi, even if the manifold only sees 8 or 9... I'm assuming there's going to be SOME drop in pressure in the manifold unless the I/C is super efficient. I had considered and still do consider getting the signal for the wastegate from the manifold, but haven't really gotten enough information yet to determine if this would be any better.

 

Your info about pressure loss vs. volume of air does make sense... would be nice if that is correct and I wont have to mess with it or worry about running suddenly leaner.

 

Oh and about choosing between 3" exhaust or the I/C, I did want to say that it is more important to me (for very obvious reasons to anyone who has followed along with any of my posts here) to choose the option that would be more beneficial to engine life, as opposed to whichever option would net me more power.

 

So I'm still thinking I/C might be the better choice... funny though how in most respects the two options seem like they would offer approximately the same benefit (more power, cooler running) there is one area where they are totally opposite... LAG. The I/C will add more of it, the exhaust will get rid of it. That fact puts me back to 50/50 on the matter...

 

ARGGGGGGH what to do what to do!!!!

[BayAreaZT]

I would recommend the IC install. If engine life is a priority, the IC does add a measure of safety and will give you peace of mind when running above stock boost levels. Sure there may be a slight increase in lag but it will be minor and by no means will it make the car no longer enjoyable to drive. As for the exhaust, you could always just cut off the 2.5" section I'm running straight out the downpipe right now and it sounds like pure evil

[Guest bastaad525]

been there, tried that... couldn't stand the volume of the pipe just dumping with no muffler or anything when I had it dump at the diff.

 

However, the good news is that yeah, I could probably just get away with cutting that last section, the 2.5" piece with the two bends, and replacing that alone with 3" mandrel and a real muffler.

 

Okay, so one vote for I/C first.

 

 

By the way, can anyone tell me what the diameter is on stock 280zxt exhaust piping? Does my current setup at LEAST flow better than bone stock??

[Sean73]

Just doing some "back of the envelope" calculations, I figure you lose about 15% air density at 10 psi by not using an IC that's atleast 85% efficient. I figured optimistically that your turbo was 75% efficient.

 

With a good IC, you'll gain most of that air density back, but turning down the boost to 8 psi will result in a 9% air loss, and to 7 psi will result in a 14% air loss.

 

So, at 7 psi, you're at a zero power gain/loss, but as a side effect you might have gained a cooler engine that's more detonation resistant.

 

Prefereably, I would address the fuel problem first before pursuing more mods, since fuel is your limiting factor right now. But if you must install the IC, I would set the boost at 6-7 psi, go to the dyno, and see how it behaves.

 

One other thing, is that if you ever plan on doing the Z31 ECCS, now is the time to think about it. Getting rid of the flapper gives you more flexibility in IC and intake plumbing.

[Scottie-GNZ]

While I agree with your installer on how to route the pipes, I fail to see all the added bends he thinks it will have. That is how I did mine and since Drax has a nice pic of his similar system in a link, take a look at that. The components required to increase power in a turbo engine are so related that it is really tough to do one and not the other(s). E.g., increasing power with an exhaust upgrade will require more fuel to support the added HP. Installing the I/C means you can turn up the boost for more power but the restricted exhaust will create backpressure and therefore more heat and the added power needs more fuel. However, your press-bent 3" exhaust is certainly better than stock so I would go with the I/C and leave the boost alone until you address the fueling. While a good 3" exhaust will add HP, the difference will not be that noticeable at your power level and because you already have something better than stock. I ran a single 3" mandrel pipe with 520hp so not having a 3" exhaust with 200 wont kill you

 

Sure I confused you even more.

[fl327]

Stock zxt exhaust is a very thick 2.5inch pipe, to cut down on turbo noise im sure. Just route the intercooler, and cut the muffler off

[Guest bastaad525]

Okay I/C it is then. For some reason I always had this idea that my exhaust might actually be worse than stock *shrug*... glad you guys cleared that up for me.

 

Well I've decided I'm going to hit some of the local speed shops today and try to get the pieces I need to install this thing. Local shops want a bit too much for my tastes (about $500-600) for what really seems basic to me... I was going to get one of the universal piping kits on ebay but after thinking it over it seems to me I would only use maybe half of the parts included in the kit (which is about $200) AND I would also need to buy extra parts to make it work (a couple reducers and silicone elbows, about another $100), plus fit was gonna be an issue and I was probably going to have to enlarge the holes in the rad support. I'm willing to bet if I buy the only the parts I need, seperately, and pay one of the local muffler shops to cut whatever pipe sections I buy, and do the install myself or with the help of a friend even, I can pull it off for more like $250... okay so not much of a savings over the ebay kit but at least I wont need to cut the rad support if I can find the parts I have in mind. So I MAY be able to get this in pretty soon, and may have enough money left over to address the fuel issue as well with maybe an FPR and some dyno time.

 

This is gonna be sweet....

[Guest bastaad525]

Any problem with using two rubber elbows (as opposed to silicone elbows) like what is in cygnus' picture up at the top of the thread? For some reason every shop I have spoke with to get these parts has some kinda hang up about me using rubber parts instead of silicone.....

[cygnusx1]

I am not sure what composition of rubber the elbows are. That would make all the difference. Whatever they are, they are holding up perfectly at 14psi. What you don't see from the picture is that they are about 1/4" thick walled. They are also relatively cheap.

 

I have posted this place before but here it is again:

 

Piping/Tubing source:

 

http://shop.airflowonline.com

 

EDIT:

The drawback of rubber would be twofold.

1) Possibility of melting.

2) Flexing under pressure causing lag (very minimal I would think).

[Guest Cronic]

I'll try to answer as much as I can with my limited knowledge...

 

That setup in the picture is very good. You will not expierence much heat increase.

 

As for the boost, logically, if your AFM is reading 10psi of moving air into the engine, it will compensate by adding fuel for that much boost. If in fact you drop to 8psi by the time it gets to your engine, you will richen up a bit.

 

Im a little confused on why you run lean at 10psi. I was running 15psi, and still hitting 10:1a/f Then again, my turbo is kinda old, and gives out around 4500rpm (drops boost to 10psi).

 

There will be a SMALL amount of lag. 1-200rpm.

 

With my FMIC I still make full boost (20psi) before 2000rpm.

 

BOV placment is almost irrelevant. No matter where you put it, it will work. Mine is just before my extra injectors, about 12" from the TB.

 

Most people would say safe boost, for stock fuel system is anywhere from 12-15psi with an intercooler.

 

Hope I helped. Feel free to PM me if you have any questions.