Ford Mustang Forums banner

1 - 20 of 31 Posts

·
Registered
Joined
·
204 Posts
Discussion Starter #1
So looking for advice on what, if anything, to change on my combo.

I bought the car with F-cam, Vic Jr. heads, Edlebrock Performer (yes the very old one) intake, 3.55 gears, and a crappy Treadstone 76mm turbo kit. Shortly after putting some real miles on it the cheapo SS headers developed 3 different cracks. Rather than weld them up, I decided to replace the turbo kit with components I selected myself.

I talked to 3 turbo vendors, they all recommended something different in turbo size. My goal was to push the stock block, and have a fun street machine with maybe a couple trips to the track to see what I can do with it.

In the end, I got what sounded like good advice, and went with Comp turbo 67mm, triple BB, billet wheel turbo. The advice was, you want the smallest turbo that will meet your needs. My needs were 500rwhp and fun on the streets.

Fast forward to dyno today. On 10lbs boost it made 480HP and 575TQ. The difference between HP and TQ is crazy to me. Looking at the dyno graph I would like to flatten the torque curve out some and raise the HP some.

Would an intake change accomplish what I am looking for? I think the Performer is the weak link in my combo but I know it is good for the street.

Take a look at the graph below and let me know what you think. Is the quick TQ peak and then drop off, accompanied by the HP curve and indication of the intake being a bottleneck?

 

·
Registered
Joined
·
486 Posts
I'm no expert or now much about tunning but hp and tq are suppose to cross at 5252rpm and it looks like yours is at 4300ish rpm. Something is not right.
 

·
Registered
Joined
·
341 Posts
I agree. With 10 PSI, I made 500 RWHP and 560 TQ. This is an earlier dyno of mine, but mine crossed at 5253 and has a very flat torque curve. After some changes, it made a little more than this but I didn't get the print out.

 

·
Registered
Joined
·
204 Posts
Discussion Starter #4
Yeah you are right. I thought they were always supposed to cross at 52xx. I'm not sure what to do at this point. I guess i can call them and ask about that.
 

·
Registered
Joined
·
23,225 Posts
hp and tq always intersect at 5252 rpm, its simple math.
 

·
Registered
Joined
·
204 Posts
Discussion Starter #6
OK as indy stated, so my tuner did also. After talking with him explained that the horsepower and torque scales are different. Loving my tuner by the way, who helped me out with showing me how to scale it different and the result is the following graph.



So back to the question, intake swap in order if I want more power under the curve?
 

·
Registered
Joined
·
997 Posts
Id enjoy the power you have now and save the money for a better block because eventually you'll want to up the boost
 

·
Registered
Joined
·
204 Posts
Discussion Starter #8
I hear what you are saying but won't that just give me the same shaped graph, the difference being that the numbers will be higher?


I'd like to see horsepower keep climbing, and torque be flatter. If I'm thinking about this right I could make a combo change to reduce the low-end torque and gain high end horsepower.
 

·
Registered
Joined
·
23,225 Posts
put a bigger hairdryer on that doesn't lose cfm at higher rpm, but does at lower rpm
 

·
Registered
Joined
·
7,628 Posts
what's size exhaust housing are you running?
 

·
Registered
Joined
·
4,970 Posts
I hear what you are saying but won't that just give me the same shaped graph, the difference being that the numbers will be higher?


I'd like to see horsepower keep climbing, and torque be flatter. If I'm thinking about this right I could make a combo change to reduce the low-end torque and gain high end horsepower.
His tuner is correct. HP and torque lines on a graph only cross at 5252 when the absolute scale number of horsepower and torque are the same.


If you look at his graph closely, you see HP=TQ at 5252.
 

·
Registered
Joined
·
204 Posts
Discussion Starter #13
I agree. With 10 PSI, I made 500 RWHP and 560 TQ. This is an earlier dyno of mine, but mine crossed at 5253 and has a very flat torque curve. After some changes, it made a little more than this but I didn't get the print out.

Dave what is your H/C/I combo?
 

·
Registered
Joined
·
1,803 Posts
Indy is correct about the larger compressor. Also eliminating that intake and going with a single plane carb style EFI intake manifold with 90" elbow will pull some torque from the bottom end and produce more power up top. see pics below for examples



 

·
Registered
Joined
·
204 Posts
Discussion Starter #15
Don't get me wrong -- I like torque down low. I just don't need 575. Any guesses how drastic the low RPM torque would be effected by a move to the 90 degree elbow intake would be?

My goal is to get as much HP under the 500/500 curve that I can up to 6000 RPMs.
 

·
Registered
Joined
·
461 Posts
What does the tune look like? My guess is the tuner is pulling a lot of timing up top to keep the stock block alive. A boxed upper would move the hp right but to be honest I would run it as is. Should easily be a mid 10sec street car.
 

·
Registered
Joined
·
7,628 Posts
is it me or does the op's torque fall off rather fast
 
  • Like
Reactions: TomR

·
Registered
Joined
·
204 Posts
Discussion Starter #19
What does the tune look like? My guess is the tuner is pulling a lot of timing up top to keep the stock block alive. A boxed upper would move the hp right but to be honest I would run it as is. Should easily be a mid 10sec street car.

Once the boost kicks in the timing is a flat 16 degrees.

Yep, I hear you. I know I'm working with basically a 500HP/TQ limit, and I just want to maximize it across the RPM range as much as possible. Kind of a waste of torque early on. I'm knitt-picking, but I work as a network engineer and I like fine control of things. I would just like to maximize it.
 

·
Registered
Joined
·
204 Posts
Discussion Starter #20
is it me or does the op's torque fall off rather fast
I agree. Especially when a previous dyno run, albeit with 11.5lbs of boost vs. 10lbs of boost, showed a much flatter torque curve. On that run however the clutch started slipping and so I'm not sure how trustworthy the data is.

Came back later with a new clutch, and 1.5lbs less boost, and got the posted run. Exact same dyno.
 
1 - 20 of 31 Posts
Top