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YOUR RESEARCHX51 Experts
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Run carrera s's and x51's in gtb
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Suggestion · Original poster
So far, they've been running carrera s's and x51's in GTB.
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Suggestion
How is it going to affect where you can run with PCA?
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Car is finally finished! I have pics on the race forum if anyone is interested...turned out great...Autometrics rocks.
Question is: What are the best mods for the X51? I need a little more hp and less weight. I still have stock headers and cats, but did the air plenum, which seems to add a little power in the 6500rpm range. I also have cold air intake. Any experience out there with this engine??
Rog,
Your car turned out great. Regarding the X51, I would dyno it with the cats and with straight pipes. I can't find the dyno sheets right now but I recall picking up something like 17 hp at the wheels. It was a huge gain. The tradeoff was not having any torque under 4500. Ditching the cats also got rid of a bunch of weight and reduced the temp in the engine bay. And, it's cheap!
Jim
Wow, that sounds good Jim. But what about the sound problem? I do many event at Roebling, which has a limit of something like 103db.
Are you doing PCA at the Glenn?
103 will be a problem. I always carried my cats with me. You could switch between cats and straight pipes in about 10 minutes.
I won't make the Glenn this year. I'm headed up to Montreal to do the IMSA GT3 Cup race at the F1 race next weekend instead.
Jim
Jim,
Looking for a tip here and to confirm. Your saying running w/o the cats and the straight pipes is the way to go for more top end? Or w/cats and the straight pipes?
Thanks!
Not sure. I never tried them. I would say this. Don't assume anything. Test it on the dyno.
It was our experience that the X51 made the most power with 6 inch straight (actually curved) pipes coming off the header and going straight out the back of the car. Like I said, torque was a real problem below 4500-5000 rpms but the car screamed above 6000. Don't forget your earplugs.
Jim,
Thanks for that... I already experienced the torque loss with just the muffler bypass pipes and with them it did pull hard past 4500 and up. In fact surprising the heck of of some higher end pcars down the straight-aways.
-P
Yep definitely worth a dyno test. It's funny though, I haven't tested the plenum on the dyno yet, but I DO get a surge of power from 6500rpms and up. Have you guys noticed this with your x51's or could it be the plenum?
mine is just a 3.6 in a car that used to have a 3.4. No x51 for me sniff. Not for lack of trying on my part.
Rog, when you say you have the stock headers you mean the ones that come w/ the x51 engine not the stock 996 ones right?
Right Paul. If fact, headers that came with the x51 are probably very good. Just looking for that "little extra" for final touches. I definitely want to get the rear lighter.
The X51 in any form has most of it's power up top. I'm not sure if the plenum is adding to that or not. How is it going to affect where you can run with PCA? I suppose it's easy enough to change that you could swap it if they have an issue.
If it is adding, I'm sure it isn't a tremendous amount. Haven't seen any problems yet in GTB with it. But, the class is still developing. So far, they've been running carrera s's and x51's in GTB.
