While visiting SP this week, I decided to take advantage of some of their innovations and went with the Boost Actuated Exhaust Cut-out. My original intent was to install the pair. Due to time constraints and to make life simpler for all, rather than attempt to remove the downpipes on the Greddy Kit (PITA), we opted to install a single dump in between the 1st set of behind the cat pipes seen below:
***(I apologize for any blurry pics, only had my cell phone)***

Before Shots:




After:




First came assembling the actual 3" cut-out with the necessary down facing tip:


Then some more fab work:



Test fitting (Tacked it up):



Then final welding run the boost line and voila:



Done.

I utilized this set-up to counteract the anticipated hp losses I would incur by going with the Cosworth intake. Worked out pretty well. No overall power losses than previous set-up.

 

awesome work.

 

Nicely done. You can now run just about any (restrictive) exhaust and not have it make a bit of difference to your power curve.

 

Thats right! And if down the line I change turbo set-ups, I can still retain the benefit of the cutouts. Or if I sell the exhaust, someone will gain an awesome set-up built right in.

 

That looks awesome

 

wait... you anticipated loss in hp with the cossy? thats not what i wanted to hear before i installed mine.

 

I want a video

 

Yes. Its not a very FI Friendly manifold for the larger set-ups. For your basic 400 hp stock block stuff its fine, but based on my discussions with Larry, you can see rwhp losses of anywhere from 30-60 hp, depending on your set-up. That basically sealed in my decision for the exhaust cut-out...Larry can tell you, I've been hounding him for the cut-outs since my last trip there.

And the best part about the cut-out, is that it requires NO RE-TUNING!!!!

You heard me right, no re-tuning is required. So if anyone wants to make a quick 30-50 rwhp get the cut-out from SP and have it welded up anyway you can for some cheap hp.

 

Yeah me to. Shot plenty with Reid's vid camera while he was out of the shop. Hopefully he can upload something soon. You will se a test video we shot with me giving the car some gas and Larry connecting the boost hose to hear the difference of the cut-out on and off. Pretty cool.

And its not ridiculous either. Sound is ground shaking though. Deep Grumble!

 

When I dyno'd my Cosworth I lost midrange torque, but it picked up above 6000 rpms, just like all the other dynos I've seen (this is compared to a Crawford).

Lots of variables (ignore the comments, both are at 15 psi open loop boost control with no meth), but this type of dyno seems consistent:



So Randy, I think you do lose peak torque, but gain peak whp with the Cosworth, and a flatter torque curve...

 

I know a few people that have tested the Cosworth back to back against the stock intake and have all lost HP, one NA - 16 rwhp and one FI - 50 rwhp. On Randy's car I had to take out fuel almost everywhere and a ton above 7000 where it just didnt want to move much air at all. Id keep the stock one with a spacer or just get the CJ one. The CJ is the only one that I can personally say will give you huge gains!!

 

I would have been happy to be your test mule on that CJ Manifold Theory Larry. LOL

 

Looks like you may have picked up 5 rwhp but lost 20 ft lbs or torque!! Not a good upgrade!!

 

HA, I called it
looks like excellent idea to avoid using 2 of those 350$ valves! very nice!
so they felt confident that 1 3" dump was enough ,or is that twin 3" pipes to a 4" dump. That would be excellent

Pretty odd that you didnt need a retune based on the advertising dynos that SP uses. There's no way they gained that much power without retuning the car. An extra 50+hp is not a trivial amount of gas because you are tuning in different cells since the boost curve is different

Just curious to as why you dont sell your cossy if your are losing power with it? Too bad Charles wont make his mani with the side mount TB.

on a side note, you said you had to take out fuel. What was the % ETOH in the gas compared to last time? I know the ProEFi is supposed to interpolate, but if the base tunes on either end used different amounts of ETOH, then of course you had to change the fuel table to get the proper interpolation.

 

Well, unless you're looking for a flatter torque curve... Spinning street tires at peak torque is no fun either. I agree, it's not a "good" upgrade compared to an typical aftermarket setup (spacer+non revup or APS or Crawford). Wish there was something better...

 

I had about 3 gallons of 93 pump and added 10 gallons of E-85. I wasn't in the car so I don't know the actual %. Larry can advise.

 

congrats... Looks nice.. Now theres something else i want too add.......

 

Thanks for the response!

The cossy is definitely a pretty piece! If you ever change injectors you can go with the short 40ish millimeter Injector dynamics and go back to any plenum you want.

so many neat changes that havent been really document before. Hopefully you guys have boost charts from the initial tune /after cutout as well.

I would guess if you didnt have to tune much for the cutout, that goes to show how free flowing that Evo TT must really be! Possibly since the valve slowly opens you might not get such an abrupt left shift in the boost curve. The charts will be very interesting!

Maybe I will resuse on injen SES exhaust again

 

That is actually pretty neat, doesn't look to hard to construct one either. thumbs up in for video

 

Lots of trial and error by people who do this every day of the week. It's not easy. Now unless you are an exhaust fabricator, in that case, its probably easy.