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Discussion Starter #1
Hello, I'm new to posting on the forum, but have used it as a great resource for the past few years, so I'm hoping to get some specific advice on the build I completed today. I want to preface this by mentioning I'm no stranger to a high performance T-Bird (this happens to be a very well kept '97 LX), but this has been my first build utilizing the 4.6L and fuel injection (former '89 had a BB 454). I had my local performance shop, Precision Auto in Xenia for those that might be familiar with their work in coordination with the shootouts once ran here at Kil-Kare, assist me with the build as they came highly recommended and I do believe they've done solid work aside from my final output. My engine has about 70k on it, with the transmission rebuilt almost 3 years ago (not sure if trans came with previous owner's new engine, otherwise it had about 118k at time of rebuild). Here is my build info:

- MHS Stage 3 Head/Cam Combo with Stage 2P cams (was charged 25.5 hours for the top end swap alone, from which I'm still in shock as I supplied all parts sans fluids, and heads were assembled)
- MHS Mildly Ported PI Intake
- BBK 1780 78mm Throttle Body + Plenum
- 76mm C&L MAF
- 24 lb. injectors
- 10" TC from Dirty Dog with 32-3500 stall (with 35,000 btu trans cooler)
- 190 lph fuel pump
- Trac-lok differential with 3.73 gears (and diff support brace), installed by SCP and Dirty Dog
- 2.5" full dual stainless exhaust on stock manifolds

NOW, after 3 hours on the dyno, the best numbers were 248 hp and 273 ft-lbs. of torque (around 4,050 rpms) in 90.6 degrees and 29.41 in-Hg and 35% humidity, SAE @ 1.03, A/F @ 14.61.

I'm shocked at these numbers (given I've tested stock GT's with better output). I do know there was a bit of trouble with slippage on the converter but my best guess is that I could've lost 10% power at most from it.

However, after driving the vehicle, it truly feels slower than before the top end swap (when I had a BOC tune, the new differential and gears, MAF, and exhaust). I easily expected on the dyno to breach 300 horsepower, and thought little of the actual numbers before I was able to drive the car, but it drives as slow as the dyno indicates. I'm really hoping the whopping loss is due to a very poor tune (I'm completely unable to hit WOT at cruising speed...which I'd attribute little to the new converter....).

I'd really appreciate any input. 3 years of preparation and lots of cash for this build is looking like a huge waste of time and money that I'm already considering getting rid of, if I can't make sense of this issue. Thanks.
 

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Your numbers are rather similar to mine. My guess is the stock manifolds are what is causing the difference in numbers between our builds since they are more or less identical. Long tubes or midlengths are practically required with these cams, I'm guessing 20-30 HP can be gained with them...

I'm hoping the A/F is what they measured at stoich. At WOT your A/F should be closer to 12.5.
 

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3 hrs on a dyno and they couldn't get the a/f ratio where it needs to be? Sounds like idiots to me.

Alas no one is going to know if it is a tune issue unless your tuner discloses any and all info we request and you provide proper datalogs from those dyno runs.

BTW, there's not enough in your head/cam combo to break 300rwhp in a std bore 4.6 with stock compression and crappy log manifolds. There's just took many losses. KDanner, JohnnyLangton, and a few others broke, or broke even, with 300rwhp with a lot more compression and some serious flow.
 

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Discussion Starter #4
I apologize for the silly mistake, MAX A/F was 14.6 and it appears at WOT it was floating around 12.5. I was in a rush to type the initial up and failed to mention that.... These guys aren't known to do bad work, but I'm not sure how well that translates into tuning ability. Some additional information: I believe wide open shift (I'm assuming for 1-2) was set at 6k...but haven't tested this and other shifts enough to be sure, but suppose this could affect my inability to go WOT at highway speed.

I won't argue that a good set of headers could uncork some power (by the way, since you mentioned our builds are similar, what numbers are you getting?), but don't think the stock manifolds are as much of a hindrance as you might suggest (if I'm looking for lower to mid-range performance), and have heard good things about ported stockers for their price.

Also, Mr. Maestro, what's your baseline for "stock" compression, before or after the new heads? I can't recall off the bat before numbers, but my guess now is I'm in the neighborhood of 10.4:1 or 10.5:1...but perhaps you have some further knowledge here as well, and would you agree that the biggest physical loss could be with the exhaust?
 

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Discussion Starter #7
Used to run a big block....for the 300% price bump from my quote, I could have brought those 700 ponies back from the dead. Damn the 4.6.
 

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Those numbers actually sound about accurate for that setup on a dynojet, however I agree, with that much time they could have done more with the AFR, more importantly if it drives good and puts down good track numbers who cares.
 

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I apologize for the silly mistake, MAX A/F was 14.6 and it appears at WOT it was floating around 12.5. I was in a rush to type the initial up and failed to mention that.... These guys aren't known to do bad work, but I'm not sure how well that translates into tuning ability. Some additional information: I believe wide open shift (I'm assuming for 1-2) was set at 6k...but haven't tested this and other shifts enough to be sure, but suppose this could affect my inability to go WOT at highway speed.

I won't argue that a good set of headers could uncork some power (by the way, since you mentioned our builds are similar, what numbers are you getting?), but don't think the stock manifolds are as much of a hindrance as you might suggest (if I'm looking for lower to mid-range performance), and have heard good things about ported stockers for their price.

Also, Mr. Maestro, what's your baseline for "stock" compression, before or after the new heads? I can't recall off the bat before numbers, but my guess now is I'm in the neighborhood of 10.4:1 or 10.5:1 Yup that's about right--I meant to say "stock-ish"---this is as high as most people go unless they are really serious---once you make the choice to get custom pistons to get to 11:1 and higher, that's where the gains start compounding each other....but perhaps you have some further knowledge here as well, and would you agree that the biggest physical loss could be with the exhaust?
You said it----good mechanic work simply does not translate into tuning ability. Heck just look at your A/F ratio curve---there's no reason why a good tuner should not be able to get that thing straight out DEAD, as in completely flatlined. Speaking of which, why in the world would you go with a 76mm C&L maf when you could be running an 80mm or a 90mm ford maf? Sounds like you didn't do your homework there. Are you running the type with a sampling tube? Did the tuner adjust the maf transfer function? Or just the injector slopes? or Both? What software were they using? Did they burn you a chip that plugs into your EEC? Did they sell you a programmer to flash the PCM directly? Were your cams degree'd properly? If so, using what method? What were the initial compression readings in the cylinders? Did they adjust the torque converter lockup schedule? LOTS of unknowns here.

Stock manifolds aren't much of a hindrance for lower to mid-range performance, but then you're complaining about not hitting 300rwhp. So which is it? Can't have both here. If you want 300rwhp in an MN12 you need big cams and a very good flowing intake + headers, no way around it. I wouldn't consider the exhaust a physical loss----but it could be better. It's like your compression, 10.5---is it a loss that it is not higher? Yes and no---No because 10.5:1 is decent, but Yes because 11:1 would pretty much automatically yield a 2% increase. Doesn't seem like much, but everything adds up. Same thing with exhaust. Those cams with the low LSA could have really used the longtubes, but you let them go.
 

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Discussion Starter #10
SCP had given me a deal on the C&L and sampling tube, but I do agree it needs replacing badly. Cams came in nearly perfect according to MHS, as heads arrived assembled. Using SCT X3 (I'm still learning what all goes into eec tuning, so please forgive my ignorance). I'm assuming they didn't adjust the lockup schedule, but just a guess, and I also believe I'm at 24 degrees total timing, and really hoping they meant initial when I was informed of that.

Never said I was going for low-end performance:) sorry for the ambiguity. In my follow-up with the shop I'l be sure to ask about the other unknowns, so I appreciate the input.
 

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Sell that C&L crap on the mustang forums. They eat up that crap like crazy. Get an 80mm ford maf and call it a day (90mm LMAF./Terminator maf if you're doing boost later). Although, don't get me wrong--I'm not implying you're losing power by not switching mafs; what I am saying is that you can get a proper tune with a ford maf that you can't get with the "calibrated" crap.

Also, I don't understand what you mean by "inability to go WOT at highway speeds". WOT is strictly a throttle position--if you floor it, you're at WOT. Are you trying to describe a (down)shifting problem??
 
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