As some of you know, I have started an FWD V6 MP90 project. The project car is still in a shop and not available to do test fittings. In the meantime, since the original MP62 kit was sitting around, I thought it would be interesting to install it on my 2003 Alero, which is totally stock, and low mileage. This would give me more insight into the kit construction process. I also needed to assess the condition of the old MP62, and compare any drivability issues with those of the highly modded track car.
I wanted to go for what would be close to a "dealer-installed" add-on. I did not follow the kit instructions on some things -- partly because the 2003 was different than earlier models, and some I did to test some ideas.
Installation differences:
1) Stock EGR left in place on upper intake manifold (not re-routed as in original kit).
2) Power brake hose left in stock position, but extra check valve added in line with it.
3) 1/4 inch spacer added between SC inlet and throttle body to match stock 2003 IAC opening.
4) Formed 1/2 inch hose routed from rear valve cover to stock coupler post-MAF, to keep MAF cleaner.
5) Modded stock water tower and routed heater hose under SC, over transmission.
6) 2.2 inch pulley installed.
7) Added formed piece to overflow tank hose.
Problems:
1) For some reason, I had to cut a notch in the battery tray to keep the bypass valve from contacting it.
2) The MAF sensor plug was too close to the fuse box, maybe 1/16 inch, so I put a pad in between them.
3) Because of the spacer installed on the SC inlet, the throttle body is too close to the airbox, put another rubber pad in there.
4) Heater hose from T-stat housing contacts SC. I changed the corner hex-head SC outlet bolt to a round, smooth allen-head type, wrapped the contact point with silicone tape, and wrapped the hose with header wrap.
Performance (so far)
1) Drivability normal, handling slightly different.
2) No DTC codes of any kind show up on scans.
3) Throttle response is terrific, but the system is overly sensitive to ambient heat. On a cool day, performance is much better than stock. If the outside temperature gets much above 85 degrees, available power drops quickly and gets to a point where it is actually slower than stock due to timing pulled by the PCM. (IAT and KR)
My conclusion (which most of you already know
) is that the kit only, as a dealer-installed option would never have flown. On a GrandAm/Alero model that also included better exhaust, less restrictive air intake and throttle body, and computer reflash, then probably yes. But even then, I doubt the HP ratings that some claimed on the original concept cars. Supporting mods are all-important with these kits.
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