i just got my mustang dyno tuned and am not too impressed. the #'s were 395ftlb and 321rwhp on a mustang dyno. Its built for a blower so compression is 8.5-1 and it has a custom grind nitrous-blower cam with all the boltons (gt40 intake, 75mm tb, 80mm mass)
What should i expect when i put on the vr4? I'm going to max out the vr4 so maybe i'll see 8psi.
what kind of hp will i see on a good tune? Or how much percent increase will the vr4 give me?
What RPM was the Peak on Torque and HP.
Can you scan the Dyno sheet?
I think your Torque is great with that low of a compression.
Since the VR4 will double your air volumn if you use a large enough inlet pipe and probably see 8psi easy I would say another 120hp and 100ftlb torque.
Last edited by speedytang; 10-02-2005 at 11:34 PM.
Originally Posted by speedytang
I can't scan my dyno sheet, but i'll tell ya the info. The hp peaks at 4500rpm and starts to drop off and torque peaks at 3300rpm. The problem is it was dyno tuned but they couldn't get the air/fuel to lean out more on the top end, it goes from 12:1 @2000rpm down to 11:1 @5200rpm. I had it tuned for a sc on the 302 that was in my car thats why the air/fuel is rich at high rpm. I hope i get more than another 120 hp because i see people like you speedy, making 450rwhp+ with basically stock 302 with blowers. Any sugesstions why the hp is only peaking at 4500rpm
What heads are on the motor?
14-1 compression 402ci with a little nitrous
Myself I never build a blower engine that uses a belt driven supercharger with anything under 9.25-1 and I don't care what cam is used. I have always built more power and better daily driven torque when the power is already building before the blower starts building boost. Your cam and heads can cause your Hp and Torque not being higher. 408 is a large motor for a GT40 intake. You need to get the VR4 on then you can figure out the combination because it is going to change in a big way.
it has windsor jr heads on it. I'm going to put the vr4 on in a couple of weeks i'll post my new #'s then.
With those heads and the GT40 intake with your compression I am shocked you built the power you did and I see why your out of juice by 4500rpm with a 408ci. The VR4 will not be able to push enough air in those small heads for something the size of you motor to build big numbers on the Dyno. I am not sure you will even see the 50% increase at 8psi to get the 120 rwhp.
what about trick flow twisted wedge heads? i have an opportunity to get a pair that are ported for a pretty good price, what kind of intake?
computer sim of your combo
Those are a much better match to your 408, even if you decide to stick with the GT40 for now. I am attempting to attach dyno graph pics from Engine Analyzer software, if it works, the first one shows your current setup with and without 7.5 psi @ 6k rpm, 2nd graph shows the TW heads, with /without same boost. [edit: I don't have the compressor mapping for a VR4, the SN2000 wouldn't make more than 5psi no matter what pulley combo I tried, so I ran an S-trim instead, and adjusted the pulley ratio to get 7.5psi @ 6k].
Okay, the attachment worked. You can see that the GT40 intake dies off over 4500, but with the boost pushing air through it, it should pull strong to 5500 before starts falling off. fwiw the cam I used was an F303, and 1-5/8 longtube headers.
Last edited by fanglemeister; 10-07-2005 at 10:21 AM.
Chris
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