LT1-LT4 Modifications 1993-97 Gen II Small Block V8

dyno - 1/4 mile sadness

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Old Jul 21, 2006 | 05:29 AM
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Default dyno - 1/4 mile sadness

im not understanding how a stock lt1 can have right over 300 t/q on the ground, a crap load of mods done (in my sig) and then dyno at 275 hp 270 tq?? 1/4 time is 13.8 with 1.8 60' @ 98 mph. i know theyre not gods gift to the track but man.. i told the guy at the dyno my gauges were off, my mph and rpm, could he have not dynoed it right ? could it have made that much difference? i was honestly expecting to see over 300 with these mods.




- stock cam though, it was a mustang dyno, does that really matter???
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Old Jul 21, 2006 | 05:45 AM
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A friend of mine made 260 hp and 278 torque with 3.73's long tubes, and 1.6 rockers. Stock heads, stock bottom end, stock tranny, stock injectors, and stock throttle body. This was also with the stock valve springs floating out at 4800 rpm's. It sounds like you need another tune to me. Just my $.02.
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Old Jul 21, 2006 | 05:53 AM
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i was thinking the same thing. i read from someone on here that i can pull my gauge needles off and turn on the car and set them where i need them, car still running. is this correct?
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Old Jul 21, 2006 | 07:26 AM
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Originally Posted by brynnda
i told the guy at the dyno my gauges were off, my mph and rpm, could he have not dynoed it right ?
Shops usually use an inductive pickup (like on a timing light) for RPM input, so your gauges being off wouldn't have affected the results, unless there's an underlying problem that was affecting both your tach and the inductive pickup (failing opti, arcing wires, etc).


Originally Posted by brynnda
could it have made that much difference? i was honestly expecting to see over 300 with these mods.
- stock cam though, it was a mustang dyno, does that really matter???
Yeah, a mustang dyno will really make a difference. The number most bandied about is that a Mustang dyno will read about 10% lower than a Dynojet. In reality there are so many variables that there are no hard and fast rules, and you can't reliably compare dynos from the same manufacturer let alone different ones.

Rather than absolute numbers which don't really mean much without a baseline on the same dyno, focus on the hp and torque curves. Look for dips and rough spots in your hp/tq curves, and look at AFRs which will tell you how good your tune is.
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Old Jul 21, 2006 | 07:39 AM
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when my 97 ss had full bolt-ons i only made 268rwhp and i was running 13.9 @ 100 mph. and mustang dynos show the real hp# because they simulate road weight.
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Old Jul 21, 2006 | 08:15 AM
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i really need to get dynoed find out what im making cause im running 13.7 on a 2.2 60 ft with 3.73's before i blew up the rear, so i know my top end has gotten a hell of a lot better, rebuilt the motor along with all the mods, need tuning bad though
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Old Jul 21, 2006 | 10:18 AM
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The numbers actually sound about right to me. A bigger stall convertor is great for ET at the dragstrip but bad for dyno numbers. Your wheel HP numbers put you around 325-345 fwhp. Since the LT4 is rated at 330hp with its cam this puts you just about perfect. To add some perspective a friend of mine just put down 300/300 with his exhaust only 96' LT4 Corvette (6spd car though). I really think you are right in line with you are supposed to be. I actually give you a thumbs up.

A cam with the LT4 top end will really wake the car up!
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Old Jul 21, 2006 | 11:09 AM
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Yea I would say you are losing a decent amount through your stall and auto. I dyno'd full bolt on with my 3k stall 286/315 or so. I'd say a good tune will help you out. My last one netted me 15-20rwhp.
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Old Jul 21, 2006 | 11:15 AM
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I have an A4 LT1 with LT headers, matching Y-pipe, CAI, LT4 KM and a tune. It made 284/315.
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Old Jul 21, 2006 | 12:14 PM
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what brand stall??? it should have hit on the dyno and spiked your torque to about 310...
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Old Jul 21, 2006 | 02:55 PM
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a mustang dyno will dyno less then say a dyno jet, but damn it shouldnt be that low. you need a new tune or something cause ur times at the track suck ***** for what you have. also i would get a aftermarket cam. with a stock cam and higher flowing heads its kind of a waste of money if your not gonna swap out the cam for a bigger one unless you plan on some boost
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Old Jul 21, 2006 | 03:24 PM
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I was hitting 13.30's with full exhaust (Hooker LT's w/ bullet LM setup) suspension, M/T ET streets and 3.73 gears. Trapping 106 MPH, 1.8 60'. Also take that speaker box when you race. Thats an easy 80lbs there.
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Old Jul 21, 2006 | 03:58 PM
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something is wrong with the setup or tune... yes the stall will show lower numbers but your track time should be alot lower...
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Old Jul 21, 2006 | 05:44 PM
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Do not get so wraped up in dyno #'s , track #'s are what count. My car dynoed low IMO but the track told me otherwise!
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Old Jul 21, 2006 | 07:30 PM
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What he said ^^^^^...The Mustang dyno tends to hurt feelings...As long as your A/F, timing, etc is right just let the track do your talking...Aren't you in Vegas? Isn't it pretty damn hot/humid there now? Air will have a HUGE effect on track times...Wait til the fall and have at it...

--Alan
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Old Jul 22, 2006 | 10:38 AM
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Did you have the knock sensor tuned out?
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Old Jul 22, 2006 | 02:51 PM
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look at me with all my mods and a tune and i just made 309 rwhp which sux *****. i think its due to my shorties and flowmaster muffler. anyway i'll be going for a converter next from fuddle followed by the 3.73s. then some dr's and finally i'll change the whole exhaust setup last just because my current exhaust setup isnt that old. if all that doesnt give me some low 12's im sellin this thing.
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Old Jul 23, 2006 | 05:02 PM
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Were the runs done on a Mustang dyno? Your tq numbers are way off. The hp numer is low due to your higher stall, but the tq number should have been higher due to the stall. You might need to see about getting it retuned. You have the right parts to take you into the low 13's easy, so I would guess that there is something wrong in the management(tune) of those parts. Your tq numbers should be close to 340 with that stall and those heads/cam. HP may not be much over 300, but again, that is due to how the car reads on the dyno with the higher stall.
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Old Jul 23, 2006 | 07:55 PM
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doesnt sound right to me but what do i know i dont even know how much HP my car has.
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Old Jul 23, 2006 | 11:30 PM
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Something is wrong.
Your MPH tells the tale.........Its correct for your ET and sixty foot but you should be trapping higher.

By comparison my 94 with 140k on it went 13.4 @ 104 with just bolt ons and a 1.8 sixty foot.

Get a scanner on it. Perhaps your getting a load of knock and thats whats killing it? Do you have an LT4 knock module in it?
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