SN95 4.6 4V Engine Tuning Question

[electech]

 

[TeeLew]

The torque peak in the 4-4500 rpm range seems reasonable (it will be a function of your cam and intake tuning), but the drop-off you're getting past that does not seem correct. My eye-ball dyno would expect you to see about 360-370 Hp at 6000 rpm and maybe in the 330-340 range at 7000. That flat power curve from 4500-5500 does not look like a healthy N/A engine.

Looks like my eye-ball dyno wasn't too far off for peak power and RPM! I was off on the 7000 rpm number. I'm a little curious what's going on there? I wonder if I was too optimistic or if you've still got a little something going on?

As far as driving the car, this had to have completely changed the character of it. You'll have a hoot between the cones, now!

 

[electech]

Looks like my eye-ball dyno wasn't too far off for peak power and RPM! I was off on the 7000 rpm number. I'm a little curious what's going on there? I wonder if I was too optimistic or if you've still got a little something going on?

As far as driving the car, this had to have completely changed the character of it. You'll have a hoot between the cones, now!

I think with a proper set of cams, it would make more power up top. I still haven’t pulled the valve covers to check what cams I have. I know for sure they are not from a 99 Cobra. It has 03/04 heads so it may very well have blower cams in it.

I only drove it briefly after the dyno session. It was 20 degrees and my tires are shot. I barely rolled on the throttle and proceeded to do rolling burnout. I’ll definitely have to re-learn how to drive the car. I’m actually afraid the transmission won’t take the extra torque. I won’t be doing any hard drag launches so hopefully it will hold up.

 

[Dave_W]

I’m happy with the results especially for autocross.

Well, that's a heck of a lot better, congratulations! I agree that the broad, flat torque curve looks ideal for autocross.
"Horsepower sells cars, torque wins races" -- Carroll Shelby

 

[Rusty67]

Very cool that you got it making more power with the megasquirt ECU and fuel system mods, I've also always wanted to run one of those ECUs. Looks like you already got to the end of the line. My suggestion was going to be to figure out what cam you have in there and look for a take off terminator factory blower setup. Tons of terminator guys have swapped to bigger blowers and I'm sure your motor could take the factory 8lbs of boost (or was it only 6?, I don't remember now). Anyways, if you want more juice thats an "easy" option, especially since you've upgraded the fuel system.

 

[electech]

Very cool that you got it making more power with the megasquirt ECU and fuel system mods, I've also always wanted to run one of those ECUs. Looks like you already got to the end of the line. My suggestion was going to be to figure out what cam you have in there and look for a take off terminator factory blower setup. Tons of terminator guys have swapped to bigger blowers and I'm sure your motor could take the factory 8lbs of boost (or was it only 6?, I don't remember now). Anyways, if you want more juice thats an "easy" option, especially since you've upgraded the fuel system.

I looked into that but I don't want to add that weight to the front of the car. A procharger setup is 100lbs. I'm not sure what a Terminator blower weighs but I'm sure they're heavy. Since I only autocross the car, I don't want that extra weight over the nose. I also think the axles I have and torsen would not be happy with that kind of power. It would be fun though.

 

[Rusty67]

Makes sense, weight balance is important. Have you done the full tilt boogie racing upgrades to the rear suspension of your car? The SN95 IRS was extremely sloppy and power broke a lot of axles because of it. Eliminating all the slop in the IRS will drastically increase the amount of juice the rear end can handle. I'm assuming since you are AXing really with the car you've done a lot to the suspension. If you haven't done all the FTBR stuff, that might net you some additional free power to the rear wheels without any additional motor upgrades.

 

[electech]

Makes sense, weight balance is important. Have you done the full tilt boogie racing upgrades to the rear suspension of your car? The SN95 IRS was extremely sloppy and power broke a lot of axles because of it. Eliminating all the slop in the IRS will drastically increase the amount of juice the rear end can handle. I'm assuming since you are AXing really with the car you've done a lot to the suspension. If you haven't done all the FTBR stuff, that might net you some additional free power to the rear wheels without any additional motor upgrades.

Nothing under the car is stock. I have the all FTBR stuff in the rear. I also have mostly MM stuff up front to include the K-member. I need a better set of dampers but my budget only stretches so far. I’ve been running the car for the last 4 years with only suspension mods. I finally got around to getting some more power. This season should be interesting.

 

[TeeLew]

I think with a proper set of cams, it would make more power up top. I still haven’t pulled the valve covers to check what cams I have. I know for sure they are not from a 99 Cobra. It has 03/04 heads so it may very well have blower cams in it.

I only drove it briefly after the dyno session. It was 20 degrees and my tires are shot. I barely rolled on the throttle and proceeded to do rolling burnout. I’ll definitely have to re-learn how to drive the car. I’m actually afraid the transmission won’t take the extra torque. I won’t be doing any hard drag launches so hopefully it will hold up.

Autocross isn't too hard on the driveline. You'll probably fine on the trans. Cams could be the wild-card on the top-end. It might be a good combo for your application, though, as long as you can hook it up.

 

[TeeLew]

Well, that's a heck of a lot better, congratulations! I agree that the broad, flat torque curve looks ideal for autocross.
"Horsepower sells cars, torque wins races" -- Carroll Shelby

Carroll was, at his best, a marketing guy. At his worst, a complete scam artist. The guys working for him were the racers.

You need the correct compromise and the peak numbers only tell a portion of the story. I agree that this combo looks like it will be a hell of a lot better on track, but a lot of that is due to the massive advantage over where it was on the right-hand side of the curve.

 

[TeeLew]

I looked into that but I don't want to add that weight to the front of the car. A procharger setup is 100lbs. I'm not sure what a Terminator blower weighs but I'm sure they're heavy. Since I only autocross the car, I don't want that extra weight over the nose. I also think the axles I have and torsen would not be happy with that kind of power. It would be fun though.

100% the correct answer. A blower setup gives a lot more power, but it's hard to turn it into real laptime. Reducing nose weight is massive for any front-engined car that has to turn. It's an especially big deal autocrossing.

 

[Dave_W]

Carroll was, at his best, a marketing guy. At his worst, a complete scam artist. The guys working for him were the racers.

Yeah, I agree with this. He was a pretty good driver (he won the Le Mans 24 in 1959) before getting sidelined with heart trouble, but after that he was increasingly a huckster, sometimes with questionable legality (turbine Indy car intake rules, "continuation" Cobras, various Series 1 issues, constant litigation). There's a rumor that he was repainting the original 260ci Shelby Cobra between each magazine photo shoot and car show so the public would think they were different cars off a production line. When Ford sponsored both Shelby and Bud Moore as "factory" teams in Trans-Am in 1969, the Moore cars consistently outperformed Shelby's and Ford went with Moore exclusively in 1970. From the mid-70's on, I think Shelby was pretty much just cashing in on his name.

Phil Remington was the true engineer and unsung hero on the Shelby American team. Glad the Ford vs Ferrari movie gave his character a decent part. Road & Track did a nice article on him when he passed away. https://www.roadandtrack.com/car-cu...agazines-features-the-life-of-phil-remington/

 

[TeeLew]

Phil Remington was the true engineer and unsung hero on the Shelby American team. Glad the Ford vs Ferrari movie gave his character a decent part.

Phil was a complete F-ing stud. You can throw Peter Brock and Carroll Smith in at Shelby American, as well, but Phil was the hero.

 

[TeeLew]

Yeah, I agree with this. He was a pretty good driver (he won the Le Mans 24 in 1959) before getting sidelined with heart trouble, but after that he was increasingly a huckster, sometimes with questionable legality (turbine Indy car intake rules, "continuation" Cobras, various Series 1 issues, constant litigation).

In my experience, most racers aren't drivers and most drivers aren't racers. It's a paradox.