FWI installed

But in what context are they commenting? Strip use? Street/Strip? All out street car? For guys that will be going thru a progression of more and more extreme mods, of course they should go right to a 4" intake. I just don't feel my setup and my driving habits "require" more than a well laid out 3" FWI.

The stock intake tube measures 4" but is full of baffles and ribs and resonator, and also has a curve or 2. I have a hard time believing a 3" FWI with smooth transitions from piece to piece, and no 90deg turns, would not flow a lot better than a stock setup, and be enough for what my set of mods will be. I'm going out to the parking lot right now and measure the ID of the TB intake... I have to know.

Ok, 3 1/4" ID on the TB intake.

Aaron, I think 3.5" would be a good size to go with, unfortunately there are no 3.5" pieces at Home Depot.

As I've said above, I WILL be investigating the 3" vs 4" further before deciding which way to go. I just really think the 4" pieces look like crap under the hood, and do not want to go that route w/o very strong evidence to support it. Those flow #'s you posted, are confusing. I guess they make for good comparison from size to size, but the CFM figures seem pretty odd. Someone else posted a CFM requirement formula here, and it doesn't add up when looking at those flow numbers above.

The CFM numbers are low because they were obtained using only 1 inch of vacuum.

You're right that for everyday driving you won't need maximum flow, and a 3" tube will probably do. I can understand your unwillingness to use 4" without proof that it's worthwhile. I wouldn't do it even if it gained me another 10hp. Maybe run the car with stock air box, then build a 3" FWI and see what the results are?

AA wrote:

....... Maybe run the car with stock air box, then build a 3" FWI and see what the results are?

Yes, that's what I'll need to do Saturday, as I doubt I'll find time to get the FWI ironed out before hitting the track. Though I'll be running gutted, with a K&N filter, instead of totally stock. Still a good comparison to just running gutted with a drop in filter. I'll also go on 92 octane this time, since I still have the 3.8 on.

IMO it's a good idea to let the car get aquainted (for lack of a better word) with any new mods. it always seems to take a few days of driving for my LTFT's and everything else to adjust to the changes. (i notice the same thing when it is really hot one day then cold the next, it takes a little bit for the engine to figure out whats different )

You can pull the PCM fuse or disconnect the battery for a few hours to reset the fuel trims. This should make the car "learn" more quickly. The PowrTuner lets you do this from your laptop without disconnecting power to the PCM.

My K&N showed up today, but I'm not gonna mess with this til after the weekend, or maybe some on Sunday. Still haven't found time to research 4 vs 3 some more. I'll make some runs tomorrow as-is, we'll see what a gutted airbox and K&N will do. What do you think, mid-15's? Friend of mine with a 12sec 67 GS400 will have his car there too, should be fun to watch. He just bought it this spring and is borrowing my slicks til he gets his sorted out. Got his this week, but went too wide, and they rub the fender lip.

Here is the link to where I read about 3" intake being acceptable down to 3.0 SC pulley. I don't know who wrote it though. Aaron, you posted this link in the Riv Faq on Regalgs.

http://www3.sympatico.ca/aepa/fenderwellintake.html

Excerpt:

*Note: 3" piping is suitable for L67s with stock to 3" pulley sizes and/or stock throttle body housing. With 3.x pulley sizes, the M90 should not flow enough air to cause 3" to be a restriction on most cases, and the stock throttle body will be a bottleneck before a 3" intake. 4" piping I'd recommend for those with 75mm throttle bodies and 2.x" pulley sizes. 3" piping is suitable for all L36s.

Apparently the person who wrote that felt the 3" was suitable. No one here has done any objective testing to prove otherwise, so we don't really know who's right.

What we do know is: 4" is the safest bet at the expense of a somewhat awkward-looking set-up. We also know 3.5" is a possible restriction, but it may not make much difference. Finally, we know that 3" is the highest risk , but we don't know for sure because it hasn't been done on our cars.

For what it's worth, the writer of that article feels it's okay to use 90º bends, so take with a grain of salt. Also, that was written quite a while ago. We've learned a few things, and I hope we learn some more.

And the more I've thought about it, the more likely I'll just go ahead with the 4" FWI. I'm just not real excited about enlarging the FW opening, more than anything.

If you are worried about the hole be enlarge if you want to sell the car the stock box will cover it up when you put it back in.

Dave,

I wonder if there's a way to build one out of silicone. Found a bunch of pieces here:

http://intakehoses.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=I&Category_Code=SHY

Would be flexible, so need to brace it, but I think it might be worth trying if the price fits into your budget. There are some rubber pieces here that are priced less:

http://intakehoses.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=I&Category_Code=BRHX

AA wrote:

Dave,

I wonder if there's a way to build one out of silicone. Found a bunch of pieces here:

http://intakehoses.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=I&Category_Code=SHY

Would be flexible, so need to brace it, but I think it might be worth trying if the price fits into your budget. There are some rubber pieces here that are priced less:

http://intakehoses.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=I&Category_Code=BRHX

What product would be the best to use to keep the air the coldest?

Silicone or rubber are both great insulators, that's for sure, but they're not rigid, and silicone is expensive. My concern would be that these flexible materials may deform under WOT, possibly hindering airflow. If someone made one out of steel, then slipped silicone over it, that would be sweet. Hella expensive, but sweet.

CRAP!!!!!!!!!!!!! Just typed out a long reply, then miskeyed somehow and lost it all....

Summary: Will just use the 4" stuff I have already, maybe check a couple other stores too for better LOOKING parts.

I did mine last night,but ran out of sunlight. I only spent an hour time and 55$ total so far. My current FWI is made up off the stock intake tubing with a 4 inch 90* PVC, connected to a 4in K&N crammed into the hole the fender. I didnt have all the parts i needed, and the filter is only half way in the fender with the roof flashing over it....It is at least working this way for now. I had a 5* temp. drop on the way home today!!
Going back to home depot for more parts, then to buy a new filter.

Ran out of sun on June 24th? LOL. Someone needs a light bar for Christmas. Congrats on the installation. Did you measure MAF before? Be interested in seeing if you picked up any extra air flow in addition to the IAT drop. Nice job, post pics when you can.

Unfortunately no ive never scanned my car before but i know my engine is loving the 105? degree austin air. It was hott today

You're saying the 5 deg drop was your engine coolant temp?

AA wrote:

Dave,

I wonder if there's a way to build one out of silicone. Found a bunch of pieces here:

http://intakehoses.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=I&Category_Code=SHY

Would be flexible, so need to brace it, but I think it might be worth trying if the price fits into your budget. There are some rubber pieces here that are priced less:

http://intakehoses.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=I&Category_Code=BRHX

thats a nice site!

the 5* degree drop was on the temp gauge next to the rpms on the dash. On a 100*+ day, i have never dropped below a running temp of 205*. Now with my crude FWI at idle im at 200* and while moving it drops almost to 195*

FWI is now done. PICS are soon to come, im just a lazy f-bomb

coolant temp is still at 200* , would post pics if my camera worked.. 160* stat is in the works..........................Anybody have a scanner down south

96rivie wrote:

coolant temp is still at 200* , would post pics if my camera worked.. 160* stat is in the works..........................Anybody have a scanner down south

Are you having a cooling problem? There's nothing wrong with 200. I strongly recommend not going colder than a 180 stat if you feel you must change it.

Not a cooling problem, just want to drop pulleys eventually. The term " hard freeze" down in Texas is rarely used, It has been 100 degrees plus outside for 20 years. Would that effect your opinion at all?