03

Project EP3 Si: Going 5 Lug with Wheels from Enkei and Nitto NT05 Tires

by Mike Kojima

Now that we converted our EP3 Civic from 4 to 5 lug hubs and added big brakes, there was no going back.  In order to drive the car, we obviously needed to do something about our wheel situation.  Our goal was to stuff the biggest tires we could into the stock wheel wells.  Unlike our hellaflush brethren we want big and we want traction, not stretching a narrow tire on a wide rim and stupid amounts of negative camber.  

We decided to try a somewhat aggressive fitment with a pretty decently large tire and a somewhat wide wheel for a small car.  We didn't want to have to mangle our fenders to tuck the wheel/tire combo but were not opposed to rolling the fenders.  Having experience with an RSX before we decided to try the same combination on our Civic.

For our Civic Si project, we approached Enkei for a set of their Iconic RPF1 wheels.  The RPF1 has aways been a favorite of ours with its clean looks and light weight. As we received the wheels, they came with this spiffy shower cap looking thing to protect the finish in shipping. 

We chose the RPF1 in 17x8 with a 35mm offset.  This wheel size combo fit perfectly on several RSX's that we have worked on before with the size of tire we wanted to run. Enkei also had a 17x9 with a 45mm offset that we were tempted to try but we were not exactly sure if that would work on our car.

The most technically advanced part about the RPF1 is its use of Enkei’s MAT technology.  MAT technology enables Enkei to economically impart some of the advantages of a forged wheel such as greater strength and potentially lighter weight with the cost advantages of a cast wheel.

The MAT process starts with the wheel's basic shape being formed as a  high-pressure aluminum die casting.  The high-pressure casting technique removes bubbles and voids within the metal which can cause weak spots from the casting.  The high-pressure method also gives better density and grain structure than typical low pressure poured gravity casting.

In a MAT wheel, the cast blank’s barrel section is roll formed.  This is where the barrel is cold formed by spinning the wheel blank through rollers which squish the barrel section into shape under tremendous pressure.  The cold working refines the grain, adds compressive stress and establishes grain flow in the proper orientation for the stress the wheel might see in use.  The cold working of the MAT process increases the aluminum's tensile strength due to these effects.

The strength imparted to the wheel by the MAT process allows for the wheel's barrel section to be thinner and lighter.  It is more important for the barrel to be lighter than the center due to the inertial effect when the wheel is spinning.  Since the barrel is the part of the wheel that is most often stressed by impacts, it makes sense to take advantage of the localized strengthening of the MAT process there.

 

 
Page 1 of 4 Next Page
Bookmark and Share
Comments
warmmilk
warmmilklink
Thursday, May 04, 2017 10:10 AM
I had a 17x9 +35 RPF1 on my RSX, not sure if clearances are the same on the EP3 though
Mike Kojima
Mike Kojimalink
Thursday, May 04, 2017 10:37 AM
We found the RSX has bigger wheel wells.
warmmilk
warmmilklink
Thursday, May 04, 2017 11:18 AM
makes sense... I also didn't have any rubbing issues with a 235/45-17 tire (taller than what you guys are using). but then again my ride height was a decent bit taller than you car. They didn't even tuck under the fender on a sustained 1.2g corner.

Random RSX/EP question:
after I installed coilovers on it (FA500), my steering response got a lot slower off center to roughly 15-20 degree's of steering angle in both directions. I tried a ton of different toe settings but could never get it to how it was on stock suspension. I know the coilover coverage is the next article, but I can see from the pics they're already installed. Did you guys see a similar issue? If yes, is there a way to fix it?
Mike Kojima
Mike Kojimalink
Thursday, May 04, 2017 12:18 PM
Some coilovers have different steering geometry, bump steer and Ackerman built into the steering arms.
warmmilk
warmmilklink
Thursday, May 04, 2017 12:52 PM
That's the steering arm on the coilovers thing changing all that, right? I always hated that thing...
Mike Kojima
Mike Kojimalink
Thursday, May 04, 2017 1:34 PM
Yeah it's a bad design for many reasons.
warmmilk
warmmilklink
Thursday, May 04, 2017 2:11 PM
So you guys are on Fortune Auto as well, you don't have this issue?
Mike Kojima
Mike Kojimalink
Thursday, May 04, 2017 2:15 PM
Nope
warmmilk
warmmilklink
Thursday, May 04, 2017 2:28 PM
just my luck... I'm gonna go cry in my Miata sitting on Ohlins, RSX is my sister's problem now
burrito
burritolink
Friday, May 05, 2017 1:44 PM
Mike, thanks for this EP3 Si article series. My brother-in-law and I have been wondering what to do with my sister's EP3 Si that she no longer wants. In the photos with Issac working on the rear wheel wells, it looks like you guys have installed new dampers and springs. In the suspension write-up, could you talk about those as well? Thanks!
Post Comment Login or register to post a comment.

MotoIQ Proudly Presents Our Partners:



© 2017 MotoIQ.com