I'm planning on doing my own FMIC for my 89TII with a decent size bar&plate core 18x9x3 I acquired, my question is as far as intercooler pipe sizing is concerned I was planning on keeping it at 2.25" diameter with mandrel bends coming from the stock turbo and going into the intercooler and then after it passes the intercooler I was planning on upping the size to 2.5" or 3" diameter with my stock 89 AFM mounted inline with the pipes before it hits the throttlebody. My whole reason for this idea is to keep the stock turbos air velocity up to speed since I'm switching to a larger core and then after it exits the intercooler step up to a larger size diameter pipe, that way once the throttle plates are stabbed open it has a decent amount of chilled air to ingest always ready and available. Kinda similar to those intake pipes with the oversized chambers for hondas. Also what do you guys think of the idea having a the AFM mounted inline with the air exiting from the intercooler going into the throttle body.I know right before the air enters the AFM I'm going to have to probably reduce the pipe sizeor use silicone connectors w/ a reducer to fit in with the meter and then expand it again with some silicone couplers then be able to connect it to the throttle body. I plan on having an HKS SSQ BOV mounted on the intercooler end from the turbo. Has anyone done this before and have they gotten any better gains with it! I have access to a mandrel bender and a whole load of other stuff that is why I attempting to do this set up! What I'm trying to do is maxout the stock setup on this car. It already has a downpipe and a decent catback with a TID mod once I get this setup done I plan on regulating the boost to 11#'s with an electronic boost controller which seems be to be the limit on for the stock turbos. I already have an FCD on their and have done the Fuel Pump re wire mod. As far as controlling the A/F I got an SAFC that I plan on hooking up once it is all done and then take it to a dyno w/ A/F readings and try to adjust the A/F fuel for the car according to the readings. Any Advice and comments would be helpful!

 

ttt

 

ttt

 

I'll try this one more time!

 

bump

 

Yeah, The ideal setup would be to keep the stock outlet size from the turbo to the intercooler, then go up to 2.5 on the way in the throttle plates. I also had my bov mounted after the intercooler and didn't really notice a difference (wasn't really possible to notice a difference over the stock setup). As far as the AFM going after the turbo I think there would be a problem with air blowing into a flap-type AFM rather then being sucked through. I've never seen or heard of anyone doing this or what the possible benefit would be, but if you want to try it out, more power to you.

-Mike

EDIT: you don't have a flap type AFM, I'm not sure how the S5 AFM would handle that.

I also noticed this thread is a year + old... wtf?

 

you can try to regulate the boost to 11#s with an EBC all you want but the WG will still proably creep unless you port it.

 

Keep the pipes small as possible, as this help minimize lag.
Going with bigger pipes is just going to induce lag, especially with a stock turbo.
I wouldn't go anything larger than 2.5"; 3" is overkill for a stock turbo.

Moving the AFM is a good idea, but lengthening the wires might cause more headaches than it's worth.
The stock ECU control isn't that great, and the S-AFC is going to tweak the entire set-up anyways.
I would try to keep the AFM in the stock location, unless you're pressed for space.

Keep the BOV away from the AFM.
When the BOV opens, the intake pressure fluctuates, and this causes the AFM To flutter.
This can drive the stock ECU crazy and cause all kinds of weird stuff to happen.


-Ted

 

Ted, you don't think that 2.5 would be too big for a stock turbo? This is my current dillema. I found a nice intercooler for my series 4 turbo engine into first gen project but the inlets and outlets of the intercooler are 3 inch I was thinking about using 2.5 inch piping with reducers from 3" to 2.5 " on both sides of the intercooler, but then got worried maybe 2.5 would be too big for a stock turbo. I do plan on upgrading the turbo later to a bnr stage 2 but only want to do the piping once.

So would 2.5 inch on both sides of the intercooler be ok for the stock turbo running 3 inch exhaust?

Here's the intercooler I'm thinking of:

http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT

 

For stock turbo, I would stick to 2"; 2.25" max.
The smaller pipes helps with boost response and minimizes pressure drop.

For turbos producing up to 400hp, I would go 2.5" IC pipes.

For turbos shooting above 500hp, I would go with 3" IC pipes.

This is the rule of thumb I try to follow.


-Ted

 

No it certainly wouldn't. If you look at the turbo outlet you'll see that will be a very skinny and restrictive pipe. IC pipe size is always a compromise between lag and flow. The smaller the pipe the less the lag and the greater the flow restriction. The larger the pipe the greater the lag and the lower the flow restriction. When Ted said "as small as possible", I'm sure he meant as small as possible without causing extra restriction.

It's been done and apparently it works well as improving throttle response (but not power), but you need a fuel controller so correct the mixtures as the pressurised air will make the reading lower, and result in lean mixtures. Whether it's actually worth the hassle is debatable.

Technically the S5 AFM is a flap-type AFM. It uses a sliding cone instead of a swinging flap, but their operation is basically identical.

 

thanks

 

From the stock turbo, how is it going to help flow to open it up just until it gets to the intercooler? I still disagree with you. If you look at the kits made by HKS, re-amemiya etc you will see that the stock diameter is retained up until the intercooler inlet.

I wasn't 100% sure, I've got all my exp. with s4 items and when looking into the AFM it looks like pushing air THROUGH it wouldn't be the best idea. It would be hard to keep the stock orientation of the s4 AFM through the intercooler tract, which is necessary for correct operation.

 

For what its worth: the Greddy I bought recently has a turbo outlet pipe that is 5.5 cm (2.150"), and a outlet from the intercooler of 6.5cm (2.580"). Those are inside diameter measurements. And obviously it has a reducer at the turbo outlet pipe. THe measurements were done with a six inch scale and another scale in cm. Close counts is my motto. humor

 

your using a reducer at the turbo outlet because your turbo has a bigger outlet than the greddy pipes?

 

How is it not going to help? If a pipe is bigger, it poses less of a restriction. This is very basic fluid dynamics. The flow difference between a 2" pipe and a 2.25" pipe is quite considerable, ~40% more at the same pressure.

Pushing or pulling makes no difference. Airflow is airflow. If you have higher pressure at one end of a pipe (or whatever) than the other then air will flow. Whether you create that pressure difference by lowering the pressure at one end (sucking) or raising it at the other (blowing), the effect is the same. But as I said, if you push boost into the AFM, it upsets the calibration due to the air density change, so you need to correct for that.

 

The restriction is already in place, the diameter of the turbo outlet is the restriction, opening the pipe up after that restriction isn't going to solve the bottle neck.

 

god damn it just buy the 800 dollar Greddy kit and be done with it.

 

Oh man... I never said it would "solve the bottleneck".

The smaller the pipe, the more restrictive it is. This is a very simple concept. If you have (for example) a 2" restriction in a 2.5" pipe, it does not make the system flow as if the whole pipe is 2". That's just nonsense. Once the air is past the turbo outlet, it still needs to be pushed through the pipes. The smaller the pipes are, the more effort is required to move it.

If you measure the turbo outlet inside diameter it's only about 40mm (1.6"). By your theory you might as well make the intercooler pipes 40mm also, because anything bigger will make no difference. Sound stupid? Yeah, it is...

 

.