2.5 one piece intake manifold modification

[Kevin_Hemenway]

When modifying a one piece intake for a 2.5l turbo what effect would shortening the runners have on the power band.

[tryingbe]

Nothing much if the cylinder head can't take the flow at higher RPM.

[Kevin_Hemenway]

Will have a FWD motion enforcer stage 2 head assembly

[tryingbe]

Are you planning to cut the intake manifold in half then modify it?

[Kevin_Hemenway]

possibly

[ajakeski]

Unless you just really want to spend a bunch of time on a one piece, you're better off with a modified two piece or a custom intake.

[GLHS60]

When modifying a one piece intake for a 2.5l turbo what effect would shortening the runners have on the power band.

Raises the powerband considerably, no down side, retarding the cam also raises the powerband.

There are a few good threads with pics if you can find them.

Health issues prevent me providing links at this time, maybe someone else can.

Boost Geek, Speed freak 500, Shadow Joey and others have had great success,all while using stock ported exhaust manifolds.

Thanks
Randy

[chromguy]

I was under the impression that shorting the runners would reduce low end torque. Which may be good for racing but not a DD. This is why some engines have the ability to effectively short the flow path during higher RPM using shutters or such devices.

[GLHNSLHT2]

a 2.5 has so much torque to spare that if you do lose torque it's not such a bad thing as you then hook instead of spin. That being said when I went to a ported head, ported 2 piece lower and a big plenum intake which shortened the runners by however much you do by getting rid of the stock plenum (no I didn't use a lengel upper) I was scared from all the stories that I'd heard over the years that the car would be a dog down low. Hah, it didn't lose anything that I noticed down low at all and would pull 5th gear from idle all the way to as far as you could go before running out of road.

[Force Fed Mopar]

Yeah on a 2.5, I wouldn't worry about low end at all, I'd do everything I could to make it breathe up top.

[chromguy]

a 2.5 has so much torque to spare that if you do lose torque it's not such a bad thing as you then hook instead of spin. That being said when I went to a ported head, ported 2 piece lower and a big plenum intake which shortened the runners by however much you do by getting rid of the stock plenum (no I didn't use a lengel upper) I was scared from all the stories that I'd heard over the years that the car would be a dog down low. Hah, it didn't lose anything that I noticed down low at all and would pull 5th gear from idle all the way to as far as you could go before running out of road.
Thanks for the comment. I will see what my 2.5 CSX is like once I get t on the road. Ported head with +1 etc

[Kevin_Hemenway]

From what I understood from talking to V8 muscle guys they were always trying to get long runners for top end ie. high rise intakes so i was concerned that shortening the runners in the one piece would have a negative effect on the top end speed/power band

[masterjr33]

completely backwards.. short straight runners for top end. long runners for low end.

the point of high rise intakes are to create a straighter path for the air directly to the intake valve. the intake runner length stays the same or shorter.

[Warren Stramer]

Kevin, read thru this thread. should answer all your intake questions.http://www.turbo-mopar.com/forums/showthread.php?69668-Intakes&highlight=Warren+Stramer

[thedon809]

a 2.5 has so much torque to spare that if you do lose torque it's not such a bad thing as you then hook instead of spin. That being said when I went to a ported head, ported 2 piece lower and a big plenum intake which shortened the runners by however much you do by getting rid of the stock plenum (no I didn't use a lengel upper) I was scared from all the stories that I'd heard over the years that the car would be a dog down low. Hah, it didn't lose anything that I noticed down low at all and would pull 5th gear from idle all the way to as far as you could go before running out of road.Even on my 2.2. Big upper plenum and throttle body improved response more than anything.

[shadow88]

On my modified 1 piece, I noticed lag increased by about 400 rpms, but it was totally worth the top end increase. I cut off a 1 piece just above the rail mounting holes and built a box plenum with a 3.3l elbow and 58mm tb. HOWEVER I also changed the manifold from a stock log to tbi at the same time.

[mopar-tech]

completely backwards.. short straight runners for top end. long runners for low end.

the point of high rise intakes are to create a straighter path for the air directly to the intake valve. the intake runner length stays the same or shorter.

It is a complex topic- Runner length, diameter, runner volume and plenum volume all play important rolls. The tunnel ram on my GTX has far longer runners than the TM7 I run time to time, power wise the tunnel ram lays waste to the TM7 in both torque and hp. This isn't always the case with tunnel rams, the particular unit just happens to have the proper design for the displacement, cam and head selection.

The short answer to your question is on the one piece intake shortening the runners will be of some benefit for the 2.5 engine moving the powerband up a notch as long as you have other supporting pieces. Intercooler and turbo will act as throttling devices if not properly sized.

Gary

[Kevin_Hemenway]

Thank you all for the input the thread warren linked was some very good reading. I have decided to leave the runners for now and cut the elbow off remove the top of the intake and weld on a 2.5" tube +90 across the whole thing for now as well as the larger tb.

[Kevin_Hemenway]

Thanks to all for the input i have completed my intake manifold alterations.
https://photos.app.goo.gl/doihC4G1Bg79w7sF6http://photos.app.goo.gl/doihC4G1Bg79w7sF6

[shadow88]

Cool work! Factory rail and mounting holes, factory knock sensor and vacuum port. You may regret not adding an intake temp sensor bung, but it looks good. Huge improvements in the elbow. What did you do inside before welding it up?

[Kevin_Hemenway]

inside i just smoothed out all the bumps and such no runner modifications. I will port match to head when I get it from FWD Motion. I will put temp sensors in both pipes before and after intercooler. as well as it has a threaded hole in back of intake manifold.

[cordes]

Nice work.

[supercrackerbox]

Unless you just really want to spend a bunch of time on a one piece, you're better off with a modified two piece or a custom intake.

Unfortunately, between the limited production and the popularity of the Lengel plenums, two-piece intakes are getting expensive and hard to find. Meanwhile I have at least 6-7 one-piece intakes in my shop. I have a nicely ported two-piece for my GLHS to keep original appearances, but the Daytonas will be getting modified one-piece intakes.

[Warren Stramer]

Looks good Kevin!

[Force Fed Mopar]

Port matching will do you no good if the intake runners are smaller...

[Kevin_Hemenway]

I feel that reducing turbulence can not be a bad thing.