STi reversed IM

Just wanted to post some pics of a reversed intake manifold I made for a customer. I spent some time designing and machining a proper choke area of the TGV housings and mating these to some 2.5" aluminum mandrel bent pipes. Since the intake manifold is reversed special attention was paid to ensure there was sufficient space for throttle cables and such. The alternator bracket will be replaced to relocate the alternator.

Unfortunately my flow bench is too small the do a proper comparison as to stock versus my design but it has been designed to take care of 4th order harmonics down the runners (thanks to subaru for the ease of making long runners). This will translate to a nice smooth torque band without the characteristic oscillations common on short runner manifolds. The plenum was designed with sufficient volume to give good throttle response and good low end torque. The runners also have built-in velocity stacks to improve flow.

http://www.redliners.ca/forum/userpix/2_mani1_1.jpg
http://www.redliners.ca/forum/userpix/2_mani2_1.jpg
http://www.redliners.ca/forum/userpix/2_mani3_1.jpg

-Michael

[PoLaRBe4r]

Looks good mike, nice work.

[HBoy]

Should have made a bigger plenum while you were at it (not from experience).

Looks good though, makes for a bit less piping and bends.

Actually I did a fair number of calculations to arrive at the correct plenum volume. This affected the length of the runners as the top is about an inch from the hood and about 1/4" from the pipes and such that run across the top of the engine. If I shortened the runners by 1/2" then I would lose the 4th order harmonic. All this is theory and it has yet to run on the car but we should see in a few weeks. As usual I spent way too much time doing R&D and being a perfectionist on something not many people can use (would have to be a fairly highly modded car). I am considering doing a few stock bolt-ons over the winter if this one works well.

-Michael

[teRcel]

looks good michael!

was that for guido?

Update with photos. Did the charge piping as well. I'm in the process of tuning the vehicle (standalone). Pulls pretty nicely!

-Michael

[Jdc]

That looks awesome! Very nice turbo setup.

One interesting note is that I forgot to look at the harmonics of idle. I really only looked at the 2500-8500 RPM range so at idle the plenum resonates a bit. Can be fixed fairly easily by using thicker materials.

-Michael

[jza]

Man, this is so bad ass.

[curtis.ebear]

so this project started in Aug of 2007?

One year later, its only getting the charge pipes... :?

[NickWa]

Wow looks good.

so this project started in Aug of 2007?

One year later, its only getting the charge pipes... :?

Yep, I did the manifold over a span of a few months then he bought the pipe sections, ordered a FMIC and rad from europe, then I spent a few weekends lugging my TIG welder over to his place where I fabbed and welded the charge pipes.

-Michael