Wow. You guys are making me blush
Thanks for all the support, but remember to put in the effort so you can reap the benefits.
Demon is right about the heads, they are hand ported with 3L valves, exhaust ports opened up to the gasket diameter, intake ports opened up to the gasket diameter and tapered on into the head.
Lower intake manifold is overbored to the diameter of the gaskets on both primary and secondary with just a tad bit of taper to it. The upper IM is ported at the exit ports by hand and up inside around the turn to the best of my ability. I did 6 Hours of hand porting work on that upper intake manifold and it could use a little more if I was after perfection.
The Throttle body used was the stock 60mm SVT , but I have it bored up to 70mm at the inlet to accept my MAC 70mm TB. I would have used the 70mm in the test but there was some discussion as to whether the 70mm was causing my idle problem so I just put the 60 back on for initial tuning. The 70mm proved to make a little better power at the top of my rev range when I was naturally aspirated, so I expect it will have some good benefits with the turbo.
For starters the turbo graph seems to show a bit of restriction in either intake or exhaust causing the torque to drop off above 6000 rpm.
If I don't raise the boost at all, but improve breating a bit more and carry that 260 torque all the way up to 6750, I'd put down 334 HP!!!!!
There is also the possibility that the cams have too much overlap and it may be a little more difficult at those rpms to keep the pressure the same. If that is the case, then raising the boost would solve that, but then I'd be generating much higher levels of torque in the midrange of the graph.
I know, worrying about too much torque
It is a fact that Chris (Keyser) ran as much as 270 torque on at least one occasion but nothing over that. If I start putting down torques in the 300 range then perhaps the rods may be running closer to their ultimate strength. I am still planning on running 8-10 psi here in the near future just to see what happens, but I am going to be a little more cautious.
There is another possibility also, GReddy sells boost controllers like the E-01 that allows you to control boost over RPM. It can allow smoother onset of boost and allow it to increase and decrease boost to keep the torque curve flat. I am kind of looking for a flat-line 270 torque for street trim driving, all the way to 7000 rpm.
270 torque at 7000 rpm will yield 360 wHP
with no increase in torque and no addition load stress on the rods.
Race trim with a pair of slicks and I may shoot for higher boost like 10psi with some octane adders.
What do you think Demon, restriction, cams or a combination of both causing the torque to fall off?
Tom
"SOMETIMES IT TAKES PAIN TO MAKE THE BRAIN WORK HARDER"
