My '07 GT automatic has a 100% stock engine with a non-intercooled Vortech V2 S-trim supercharger. It makes ever increasing power as revs climb. 364 rwhp at 6,400 rpm's, but it's climbing at a rate of about 5 hp per 100 rpm's. Boost is about 9.5 psi at 6,000 rpm's and 11 psi at 6,400 rpm's, so boost is climbing quickly at high rpm's, as well (gotta love centrifugal blowers).

I've been thinking about moving the shift points up to either 6,800 rpm's or 7,000 rpm's. That may push boost up to around 13-14 psi. Does that sound safe, or am I asking for trouble with a stock rotating assembly?

 

I'll be damed if I know but, Merry Christmas Brian

 

Ah, shucks, Steve, I saw that you replied and thought I was gonna get some good tech pointers. But, I'll take the holidays wishes over tech anytime. Merry Christmas to you, too. On a side note, December 25th isn't just Christmas, but it is also my birthday (as well as Alice Cooper's birthday).

 

I'll bet you $100 that you'll throw a rod. You don't even need to be running lean to end up with a blown motor. Trust me, I speak from experience with my Rotrex.

Another fact to consider is the profile of the stock cams do not really help you a whole lot at higher RPMs. There's no point in spinning it to 7k unless you were running aggressive cams with lockouts. Powerband of the stockers just don't give you a whole lot to play with up top.

 

I would think that's looking for trouble. Change non-intercooled to intercooled and I think you'll be better off and won't have to rev that high, though a bit less richer too!

 

I'm with him, go for efficient power before the brute force approach. I won't tell you not to, but ill be happy to sell you a kit if you do

 

Well, it sounds like you guys all summed up what I was thinking. Spinning those little toothbrush sized rods and non-forged pistons too fast is not a good solution. Centrifugals really shine at high rpm's, and I'm nowhere near pushing this V2 past its efficiency, so I would like to take full advantage of that high rpm rush someday. Perhaps a forged rotating assembly is in my GT's future. In the meantime, long tube headers and water/meth injection will be going on the car.

 

6,500 RPMs is about all I'm comfortable with..

 

I'm not sure if its an option or not, but a good set of heads to allow it to spin 7k+ would be on my list before or at the same time as the shortblock. Can't really utilize one without the other unfortunately!

 

I think 6800 is about as high as you want to go with stock stuff. alot of tuners set that as a redline in the tunes.. so i guess it's not an engine killer for the occasional missed shift (been there)

 

I might be missing something here, but why would you want to do meth before doing an intercooler? Don't get me wrong, I am looking to do meth after I get the built shortblock up and running. I'm not opposed to meth.

 

It's cheaper is the main reason I can see. I almost went with the non-IC v3 myself but I just felt safer with an IC setup plus I like have the instant torque of the twinscrew, and yup drives perfectly fine in the snow too!

 

N/A, my shift points were set at 6,800 rpm's. With boost, I'm just a little leary of spinning so fast since the blower makes a lot more boost at those revs. It's a safe, conservative tune, however.

 

Water/methanol injection will lower temps a little more than an intercooler, plus effectively raises octane 6-7 points allowing for more aggressive tuning. And it's half the cost of adding an intercooler, so it's a win-win.

 

Well I supposed that is true, but I'd still spring for the IC for peace of mind. You run out of meth, and you'll be running lean with advanced timing on the stock rods. Are you planning on relocating the IAT sensor to the manifold?

This is what happened to mine at 440rwhp at mid-5000RPM going down the track. Car spent more time getting custom tuned than it did doing the quarter, it wasn't running lean. Stock rods just gave in.

 

IAT sensor would go in the manifold with a tune written to dial back timing if temps exceed a preset level.

I'll only run out of meth if I run out of wiper fluid - LOL - that's the other cool thing about water/meth is that it is abundantly available wiper fluid and most kits have a fluid level guage or light available. AIS, Snow, Anderson Ford, etc. all have some pretty cool kits available.

 

Brian, looking forward to the meth project.

I entertained the thought of meth once, but my Tuner advised against it.

 

Oh my, What are these forums comming to

 

There's nothing wrong with meth, the key is to tune it in such a way that if the system failed the car isn't relying on it to keep running

 

No

12-14 lbs boost on stock motor is asking for trouble, especially non-intercooled. One advantage of meth over intercooler is not having the weight of an intercooler at the very nose of the car. We ran meth to lower the IATs and it worked very well but I don't like it (just one more thing that can mess up... meth pump...injectors etc). We will use it on our new build, only if necessary, and with caution.

Also the stock intake manifold is not designed for the mixture. Distributes unevenly between cylinders and you can get some rich and some lean, while showing safe A/F ratio. We are running more boost than most folk and that adds to our caution.