Just finished the mods on my GP, and I thought I'd post the results. The mods were H&R coil-overs w/ Helix camber plates, Alta 22mm rear bar, and Alta control arms. The engine got an M7 2% (lightened) crank pulley, Helix CAI, and a Milltek header and Milltek exhaust. I also replaced the wheels with 16x7 BBS RG-F's (11.8 lb's each) and A048's. First off, let me say that this car feels dramatically quicker and faster than my '03 JCW (only mod was the Promini CAI). The car really feels considerably lighter than the lb. reduction that they post. Half of this can probably be attributed to the lighter rotational mass of the wheels and the lightened crank pulley. They both made the car feel 300 lb's lighter, and the car really screams through the rev range. The exhaust made a considerable difference with mid range torque, but not so much with top end HP. The handling is perfect IMO, and the rear will step out gently with a bit of trail braking. Obviously I can induce some understeer with the throttle, but it is one of the most "stuck" front ends of any FWD car I've had on a track. I set the car to 1/16th toe out on the front, and will probably change that to 1/32 or zero toe. The car's turn in is so good that I would back off, and probably end up at zero toe (would leave it at 1/16 for a straight line braker though). The coil-overs are set at almost the highest position, and there is no rubbing at all (required no trimming either). Now for the Dyno results: With only the exhaust on the otherwise stock car, the results were 1.21 hp loss with 5.36 lb/ft torque gain. With the Header, exhaust, 2%, and CAI I got a 7.89 HP gain, and a 12.48 lb/ft gain in torque. I've included a couple of pictures of the car to show the wheels and ride height. Also, my dealings were with OutMotoring, M7, Helix, and Tire Rack, and all were exceptionally helpful and nice.

 

http://i50.photobucket.com/albums/f3...f/L1030383.jpg
http://i50.photobucket.com/albums/f3...f/L1030379.jpg
http://i50.photobucket.com/albums/f3...f/L1030373.jpg

 

Forgot, the Dyno was a Dynojet Winpep 7. I also have an M7 DFIC with the scoop, but haven't put it on because I'm waiting to have the scoop painted. Should have it on in a couple of weeks and I will post the results. Hope this helps.

 

That's quite a nice wheel choice ... if you have to replace the GP wheels, it's good to see a nice replacement!

 

Thanks. I personally like the feedback from a smaller diameter wheel, i.e. larger sidewall as compared to the 18's. The orig. wheels are in sealed bags stored in a climate controlled garage as are all orig. parts just in case.

 

Looks good although the arches (on all Gps) are screaming to be painted.

 

Racerxspf
The GP looks great. You have done an interesting set of mods. What was the reason for the Miltech exhaust? Was it sound quality? I am guessing that you are still running the stock GP software. Those wheels look really good, probably the best alternative that I've seen although I really like my GP wheels. I think some of you are really brave doing the coilovers and lowering the car. On the roads I drive I can't see my GP getting much lower. Steve

 

The Itch,
Everything that I've done has really just been experimental. I feel that the GP has plenty of power right out of the box. The stock exhaust sounds better IMO, a perfect blend and level of throaty burble. The Milltek is not loud, or coffee can-ish at all though. However, the mid range was increased so much that I'll leave it on. The software is all stock and the car runs beautifully. I know what you mean about lowering, the H&R's are on their highest level, and I would prefer a little more adjustability on the high side (just in case). -Sean

 

Sean
Looks as if most of your torque gains are coming from the Miltech header, the 2%, and some from the exhaust swap. That is really nice. I've been thinking about a header down the road but I want to put a few miles on it before engine mods. I'm curious as to what your final specs were on your alignment and to wether or not your car was loaded with any weight for spring height specs. I am torn right now to go with the adjustable Helix plates or the Ireland fixed 1.25. It is a 99% street car for me with a few driving schools thrown in.
By the way, how does your dyno sheet look? I'm not much of an advocate of roller results because there are so many variables and I think feeling the car on the road is a better alternative. I would be interested on how the GP software is doing on fuel condition though. Thanks, Steve

 

I've always loved those BBS RG-F wheels, and they're on my "short-list" (in 15" size) for when I get new autocross wheels. Did they fit the 14mm lug bolts without modifications?

 

Riquiscott,
Fits 14mm w/o any modification.
Steve,
The alignment specs are 1.5 in the front, 2.0 in the rear. 1/16 toe in the front and zero in the rear. The car was set up with 170 lb's in the drivers seat (my weight). The front end is almost at the top of the adjustment, and the rear is all the way at the top (to optimize corner weight). Fuel consumption seems to be normal. I agree with your thoughts on the dyno grand prix. The car doesn't really seem any more powerful on the top end, but the power curve starts earlier and is far more broad. This is reflected on the dyno sheet, and the feeling while driving. As you know, peak numbers don't mean anything. I would take 150 hp over the entire rev range over 300 hp that only appeared for 1000 RPM anyday. With my changes, the peak power spiked a bit, not not really consistantly. The torque, however, came on early and stayed there the entire rev range. So far, I've got no plans to re-map. I couldn't ask the car to run any better. -Sean

 

Sean
Where were you at on the A/F mixture? Even in stock form I feel that the torque curve is really good. Yours must be great. Thanks for the alignment specs. Steve

 

Steve,
We played around with the mixture a tiny bit in both directions, but nothing worked as well as the stock mixture, both on the dyno and on the road. -Sean

 

what's the tire size? I had 15" RG-F's but ditched them for some 16" Volks and the tire selection is up next

 

Am I reading this correct? You spent $1950 to gain 7.89hp? You are also adding a DFIC and scoop for another $1,000 plus over a very good stock intercooler that people are dying to get? How much you want for your GP intercooler?

Thanks,

Bill

 

Just goes to show that the GP designers didn't leave a lot of "low-hanging fruit" when it comes to performance gains. Still, the horsepower (and especially torque) increases he got aren't trivial.

Plus, those are *peak* increases - if you look at the entire "area under the curve" on the dyno plots, the gains might even be more impressive. For my uses, I'd personally rather have an additional five horsepower from 1500 RPM to 5500 RPM than an additional fifteen horsepower that doesn't come in until 6000 RPM.

 

There is a software tune coming that will do better than that and it only costs $400.

 

MTH doing a GP upgrade?

 

The software I saw was NOT from MTH.

Bill

 

Oh, interesting

(I just guessed - wrongly - from the price point)

 

Dimsport should be able to do the tune

 

dude, nice rims they really look great on the GP

 

The wheels are 16X7. Not selling the intercooler. The peak HP gain is narrow, and negligible. However, the wide torque gain cannot be had with any remaping. Just experimenting anyway. -Sean

 

tire size, not wheel size please :P

 

Could you post the dyno chart? I would love to be able to compare it to the curve of some MCS charts. My goal is to make around 225whp using a lot of the same type of parts/upgrades as the GP already has, as well as the other modifications you have done.

Also, you mention that the torque curve is better than in stock trim... How is this car to drive? I'm guessing that this car must have some amazing pulling power now with the additional HP/TQ and drop in rotating mass.

Thanks, and Merry Christmas!

Drew