What size intercooler pipeing should I use?

[Hot Air]

My 84GN had a spoiler that mounted on the front crossmember (?)...with you I/C tilted, you would benefit from forcing air up through the I/C rather than letting it pass under the car. Just a thought.

Vertically mounted I/C's (typical arrangement for front-mount I/C's) are very efficient when cool air is forced through them. As they are tilted they present a smaller cross-section to the wind and are less efficient. To test a theory, I look at the extremes. If an I/C is mounted vertically, it has a lot of surface area "in the wind". Conversely, if it is tilted backward 90 degrees, it has virtually no area "in the wind". Tilting it like you have will require some way to bend the air to go through the I/C to get maximum cooling of the boosted air.

Having said all that, I love the stealth of your install. Looks slick! Adding alcohol injection (chemical intercooling) will enhance the cooling.

Conrad C.

ps...I would highly recommend Corky Bells's book "Maximum Boost". You would benefit from reading it. It is available at most book store chains. About $35.

 

[dees75z]

Conrad,

I appreciate the help..............................but keep in mind I am not done with the car yet as you should be able to tell by the pics. On that note,..................I do plan on taking a piece of sheet metal and "boxing" in the IC and also running Meth inj. But I am having issues with my DFI right now and can't really figure it out. I have noone around me that knows anything about these cars or the ems for that matter so I am kindof "stuck" on it(a little frustrated while I am typing this). Thanks for the comment though!!!


dee

 

[Hot Air]

Not sure what you mean by DFI. Have you converted to aftermarket computer or are you having ECM trouble? Are you working with a chip manufacturer? Some owners have converted to the 86-87 ECM, I think. Tell us what you need help with.
Conrad C.

 

[dees75z]

I have Accel DFI Gen6 (with speed density conv) and for some reason it will not "link" with any laptop. I have tried a serial to usb which obviously does not work so then I borrowed a couple of laptops from a few buddies of mine that where older and actually had serial ports to connect to. Still no luck!!!! I am so frustrated with the situation right now that I don't want to work on it. It will start and run, but, runs very rich. No MIL, so I have no idea what direction to go on it.

 

[Boost231]

did u post up in the performance ECM thread? there are lots of people on this board that can help you with that DFI

 

[Hot Air]

I have ask folks on "General Turbo Buick Tech" section to let me know if anyone else is running the Accel DFI. Perhaps we can get you some help. Otherwise, you might want to purchased a used FAST (not the current XFI).
Conrad C.

 

[TURBOPOWERED68]

running 3" hot and cold on mine but I am running pt6765rh which is a 3" outlet anyways. Just need to make up your mind as to what you want to do. Every car that I usually do IC piping on is 2.5" hotside and 3" cold side.

dee

Trying to learn.
Doesn’t hot air take up more space (volume) then colder air?

Like the 5 in DP’s that drop down to 3 after a few inches.

 

[dees75z]

Like the 5 in DP’s that drop down to 3 after a few inches.

5" DP???? I am lost man. When I speak of the "hotside" I am speaking of the IC piping in between the turbo and intercooler.

dee

 

[TURBOPOWERED68]

5" DP???? I am lost man. When I speak of the "hotside" I am speaking of the IC piping in between the turbo and intercooler.

dee

The down pipe was an example.
The outlet of the turbo comes out hot, then the intercooler cools the air.
Doesn’t hot air take up more space then cold air?
So why would you use the smaller diameter pipe on the hot side where the air takes up more space?

 

[Chaotic GN 85]

lkdjf

 

[Hot Air]

For Accel DFI help, contact NORBS on this site or John Estill at

buickv6@comcast.net

Conrad C.

 

[dees75z]

Thanks man I appreciate it

dee

 

[Hot Air]

I just talked with John Estill...he is not knowledgeable on DFI but he did tell me something I didn't know...there is a "Performance ECM Upgrades" section on this site. It is NOT in the Tech Arena! Scroll down past "Tech Arena", past "Members Rides", past "Racing Rules" to ELECTRONICS! "Performance ECM Upgradea" is there and it does cover DFI! I kept looking in Tech Arena for a ECM related section and it is not there! So, go there and ask for help.

Conrad C.

 

[dees75z]

K, thanks conrad I appreciate it man!!! You going to BPG event this weekend???

dee

 

[Hot Air]

Dee,
No. I'm located in central North Carolina. That would be quite a long haul for me. Besides, my motor is out of the car for rebuild. Are you going? If so, take lots of pictures and share with everyone.
Conrad C.

 

[JDEstill]

Well, let's not be hasty, "not knowledgeable" is such a strong term... I admit to ignorance on such things as trying to get the PC to talk to the ecu. norbs is an excellent resource for all your DFI issues. I can help, if needed, on things like fuel maps. You mentioned the car was running real rich for example, and if you can download your program and email it to me then I can help with those sorts of things.

On the original topic of IC pipe size, while Corky does say 450 ft/s, that seems pretty far out there to me. Without knowing any better I would have set a limit of around 200 ft/s. But maybe the pipes are so short that the higher velocity Corky quoted can be tolerated.

Anyway, the piping leading to the intake manifold is easily sized. Conveniently enough, the engine takes in 231 cid of air every 2 revolutions, no matter what the manifold pressure or temperature is. So the volumetric flow of air in that pipe depends only on the engine rpm (well, and also on the VE somewhat). A 231 cid engine running at 6000 rpm will have a velocity between 150 and 175 ft/s in a 2.5" ID pipe leading to the intake manifold, whether or not it is IC'ed or hot air. This is also the reason there isn't a huge gain to be had with bigger throttle bodies on the IC'ed cars, where the throttle body is mounted on the intake manifold. The velocity just doesn't change that much with more boost or better intercooling. It just goes up with rpm. So an 8000 rpm screamer might want a bigger throttle body/IC outlet piping than a car that never sees the high side of 5500 rpm.

Now piping to an IC will be a little more variable, though not as much, because of the effect of differing boost levels on the air temperature in that piece of pipe. Since it is hotter, the velocity will be higher if the same size pipe is used as the up pipe. If the up pipe is 2.5" at 175 ft/s, the compressor outlet pipe would be on the order of 200-230 ft/s. If you want to use a bigger pipe somewhere, it makes a lot more sense to have the big pipe on the IC inlet rather than on the IC outlet.

Finally, compressor inlet piping, velocity is totally variable, huge swings with rpm and boost. If you have a car that can move 500 gm/s of air, the compressor inlet pipe velocity will be over 300 ft/s with a 3" ID pipe, 230 ft/s at 3.5" ID, and 175 ft/s at 4" ID. Totally worthwhile to go big here. And there should be nice gains for cars (such as hot airs) with bigger throttle bodies when the throttle body is mounted in the compressor suction system. The more air you move (ie more rpm, more boost, better intercooling, and so on) the bigger you want the pre turbo items to be.

John

 

[Hot Air]

John,
My bad! Sorry!! FWIW, John Estill is a very knowledgeable engineer. He has forgotten way more than I will ever know about turbo regals. He has taught me a LOT!
Conrad C.

 

[JDEstill]

No no, no worries, I knew what you meant! No offense taken at all. Just clarifying things, in case norbs doesn't have time to help. norbs is certainly guy #1 to go to. But I just wanted to let him know I can help on some things if needed.

John

 

[dees75z]

Dee,
No. I'm located in central North Carolina. That would be quite a long haul for me. Besides, my motor is out of the car for rebuild. Are you going? If so, take lots of pictures and share with everyone.
Conrad C.

Yeh man leaving in about 10 hours or so, lol. Getting excited about it cause I haven't seen a decent TR since I lived in Las Vegas. I guess that would be a little bit of a haul for yah, lol. I will try to take as many pics as I can and I know for sure that I will take some vids

dee

 

[dees75z]

Well, let's not be hasty, "not knowledgeable" is such a strong term... I admit to ignorance on such things as trying to get the PC to talk to the ecu. norbs is an excellent resource for all your DFI issues. I can help, if needed, on things like fuel maps. You mentioned the car was running real rich for example, and if you can download your program and email it to me then I can help with those sorts of things.

John

Man I would be happy if I could just get the damn thing on a trailer right now, lol. I luckily have one of the best GM tuners on the eastern seaboard just down the road here. As long as I could get a decent tune on it till I can afford a WB that is compatible with this ems then I will be a happy camper.

Thanks,
dee