custom intake advantages
 

Looking over the Coast Fabrication website I referenced in another thread, I came across this mean looking custom intake set up and am curious as to its advantages, if any, over the carrera intake in an EFI application.

JPhttp://forums.pelicanparts.com/uploa...1171659525.jpg

Individual throttle bodies (like in the pic) can be a hassle on turbo cars. Stock Porsche intakes are better than anything any of us can come up with so why not stick with a Porsche intake. You can have a Carrera intake extrude honed and it'll flow enough to make more power than the engine can handle. JMHO.

Saw one of those for sale here on Pelican a few weeks ago...

Not seriously interested in going this route, was just curious. Thanks for the replies. Craig, I saw that intake - convincing the wife would have been another story.

JP

How so? we have been running ITBs on our 935 clone for years, and have never experienced a "hassle"

The only issue is you need to balance the individual throats, which is pretty much a breeze. after that basically set and forget

These are the ITBs on our 935 clone, dual 55# injectors per throat.

The plenum and intercooler are off because we are spending a little time on the dyno tuning part throttle/no-boost areas of the map.

http://forums.pelicanparts.com/uploa...1171735914.jpg http://forums.pelicanparts.com/uploa...1171735926.jpg

My tuner was telling me about a problem he had tuning a turbo car with ITB's. I believe it was adjusting the butterflies on boost and off boost since the slack in the linkage kept it from being consistant.

What is the advantage of using ITBs over a single throttle body in a turbo application?

well, there defiently still are some. Much for the same reasons as on N/A.

However the big throttle response advatange will be reduced, from what i have seen, the guys going "all out" on their build ups are stil uding ITB's....so theres something to be had.

Better throttle response, the butterfly is nearer the inlet valve.

Getting them to work on the street is more difficult than a single butterfly.

This is what I have read on the net anyway.

I've since decided against it, but here's my thoughts. One of the biggest downsides of the 930 is off boost throttle response. Combinations of gearing, compression, cams and intake tract. The ITB's may contribute little to the max horsepower numbers but I think it would help driveability and response. That was my intention with my first build recipe of 8:1 TT ITB EFI 964 cam'd engine behind a 915. It wasn't for the biggest numbers but for response an flat torque.

The guys on Rennlist stayed consistant with the ITB's being best but difficult to keep in tune for street use on turbo application. I think it's a combination of ITB's always being more intricate than a single TB and the difficulty simply GETTING TO THEM with all the turbo plumbing and IC. I will not be able to tell you the answer since I've since divided my parts amongst two engines and will keep the ITB's for a NA car. Going the proven Carrera intake on boost.....I whimped out and decided to follow the heard.

Most all out race cars still run a form of ITB's even under boost if rules allow.

When I started my EFI conversion my builder wanted to use a similar setup to the one above, Kaspar, Holcombe, Harvey and Steve Weiner all voted for the Carrera intake over an ITB setup budget notwithstanding because there wasn't one.

Luke, I'm also going the carrera intake way but as a reference point, Nissan's R34 Skyline uses ITBs in a twin turbo-charged set-up. I drove a stock one with only 15km this weekend and yes the throttle response was incredible, though everything has great throttle response compared to my CIS 930. I must also add that it's a bit unsettling to drive a right hand drive car:)