Like a lot of guys I did mods in stages (two to be precise) to my 08 C6. The first set of mods were a set of kooks 1-3/4 headers with Kooks mid pipe with cats and a Vortex intake. With a dyno tune that netted around 434 HP. Thats all I originally intended to do but you guys know how that goes. 3 months later I read Spins posts about his 230/234 cam and I was off and running again. In addition to Spins cam I boosted the compression to 11.3/1, cut intake reliefs in the pistons per Spins reccomendation, used Comp Cam valve springs, Comp push rods, Faster Proms stage 2 intake & TB and a new Katech timing chain. The stock heads were milled, had a good valve job and were flow tested. After dyno tuning the motor made 498 HP at 6250 RPM and 454 lb/tq at 5250 RPM. This was using the stock thermostat and standard crank pulley. The dyno tuning was done on a Mustang dyno at Auto Motion here in Louisville. I don't know how Mustang dynos compare to the dynojets but all runs were on the same Mustang dyno with the same tech. The cam choice and intake are two things I would not change. Everything Spin said about this cam combination and compression boost was dead on.

How much is there to be gained by going to mid pipes without cats while using the 1 3/4 Kooks headers, installing a 160 stat and possibly using a electric water pump??? So far everything I have done has not screwed up the reliability or drivability of the car and I want to keep it that way.

 

I am by no means an expert, just a diligent reader, my bet is 15HP.

 

Probably closer to 3.

 

Pulling the cats won't net much if anything. Even if you saw 3hp who can say it was b/c of the cats removal truly?

From my experience with the EWP you likely won't gain much their either while creating stress of it "possibly" shorting out. The revs will definitely come on stronger and quicker hands down with an EWP. I've had one on my car twice now and the first time we saw no real hp gain and it shorted for no known reason with <1000 miles on it. Put the stocker back on from there. Wanted more power so tried it again. This time the car would run hot with high revs around Little Talladega. I didn't make it 3 full laps before I had to pull in and call it a day. Pulled the EWP once again so I'm finally sticking with the mechanical style pump.

Just my .02 as I'm sure a few will come on and say "zero issues" with their EWP.

 

Thanks for posting your EWP experiences.

San

 

Very stout baseline of 434 HP.

No guess on the EWP, I'd go with 5 HP on the exhaust change.

Depending upon the tune, the t-Stat could be 0 HP. Often the T-Stat is used to preserve the power you are making in warm weather, rather than add extra HP. It helps keep the car out of the IAT and ECT temps that pull timing. If the tune was conservative and done when the car was hot, you might be able to get a few more HP retuning with the stat.

why did you skip the UD pulley?

 

Just didn't know it was a viable option at the time. This is my first Corvette and the first performance car since a 67 GTO. The tune was conservative and done in February with the dyno room well ventilated so there was no overheating problem associated with it. If I had known several guys locally befor doing the work that had more experience I would have done the UD pulley with the cam.

Thanks for sharing your experience on the electric water pump. I will do the 160 degree thermostat this winter but unless I was willing to change over to LG 1-7/8 headers with new non cat midpipes I don't see spending the money to replace the existing midpipe on the 1-3/4 Kooks headers based on what I am hearing here.

 

I don't think it's worth doing. The t-stat will help keep detonation away, but the fans will need to be programmed to come on sooner. I wonder if the tuner did that already. Do you have a graph you can post up? I would like to see your torque curve. I have a similar set up and am considering milling my heads.

 

I thought about selling my 1 3/4 headers for some other brand or 1 7/8 a few times but everytime I saw graphs of others with the header I considered the power gain was not there. Unless I found some LG's used for a killer price and someone gave me a nice penny for mine I just couldn't justify the hundreds of bucks it would cost. Kooks are nice so for what it's worth I'd say let them be. You most likely will NOT see/feel the gains you'd like for the money you'd spend.