ForMySon

Ok, on an 86 iroc, I did the spin test, lifted both tires its a posi, and the drive shaft spun around 2 3/4 to one tire rotation. Gears are 2.7something, right? During my first test runs, I romped it (3/4 to full throttle), the car didn't brake traction, 1st gear only did 4000rpms before shifting at 40MPH, and did 0-60 in bout 6 seconds. Really???
WITH HIWAY GEARS??? I'm confused. This car can't be that fast.

It's basicaly a carbed 71' 350 from corvette. The last owner said it had flat pistons, a mean cam (the engine noticably lopes), head work, bored over, some alum. zz4 (not sure)intake, 4 barell. We added shortie headers through strait pipes (no mulfer, no cat), rebuilt HEI hi-power dist with upgrade advance springs, most expensive spark plugs and wires from local autostore, can't think of anything else.

In the last car 85' iroc with the same engine, if I 1/2 gassed the peddle it would brake traction and spin the car(except for my good driveing). My son couldn't do it, he would spin it around every time. So, I figure it was geared with 4.10s. Now I'm not sure. The shift points are very near on both cars. 1st gear gets close to 40mph, 2nd to 65mph.
DON'T THE SHIFT POINTS CHANGE WITH DIFFERING GEARS??? I'm positive that both cars have different gears because the 85' was way more quicker in first and second gear. WHAT AM I MISSING??? HOW MANY HORSES HP IS THIS ENGINE THROWING???

torque_is_good

what are you missing? - a true timing measurement

how many HP- spend $50 at the local speed shop and do a dyno pull or go to the track and ask to weigh the vehicle and then look at the trap speed and time. Does it really matter how many HP you have?

On second thought, forget it, stick with the 6 second story because you will be disappointed if you go to the track or the dyno. Sometimes, ignorance is bliss and you are best off not knowing.

Guest

WOT automatic upshift points are controlled by the governor and the line pressure. If you have a known combo, then go from 4.10:1 to 2.73:1 gears, and no other changes, then you'll just be doing more MPH when it upshifts. But if you don't re-calibrate your speedometer to match the "new" gears, then you'll never know it.
If the engine is all that nasty, then it should happily pull 5500+ RPM, and it shouldn't like 2.73:1 with OD.

ForMySon

Assume I got the times right. Trust me, I have an awesome balance/equalibrium thing going in me. I can fly a jet plane with flips and twist and know what way I"m facing. Same with speed/acceleration. Thanks but no thanks. some have it, some don't, just like some fly jet planes, some dont.

ForMySon

Makes since. I didn't change the speedo gears, but speedometer is accurate according to cell phone real time speed app. I'm gonna have to verify the gears in the other car.

Overdrive sorta makes the car run funny like its trying to lope. Power steering barily works at idle, got to get rpms up for it to work good.

The reason to know the HP is so I can plan on how to rebuild the trans. If the engine is pushing 400hp+ then I'm not going to mess with a standard trans. rebuild, I might even want to beef up the rear. I use to have an olds with a 455. I know the damages of powerful engines. Unfortunately, its not ready for a track, nor is one close by.

Again, someone please help me estimate the HP based on what I've said.

old z mzn

iTrader: (1)

my wife's 1994 formula does 50 in first 98 in second with 2.73's

torque_is_good

ahhh, a P@#sing contest; no thanks

I doubt that you trust your visuals to determine altitude?

nuff said

ForMySon

Sorry, not trying to have contest, but watching speedo and determining amount of time passing is possible, and can be consistant to a degree with room for error. My errors in time are consistant between one car to the next, therefore, I become my own gage.

That's why I'm here asking, because I can't beleive this car is pushing this much power. We've only spent $2500 for both cars and to do the swap over. My son flipped the last car 5 times was hospitalized for 5 days almost died, I'm sorta debating if I should somehow alter the car set up so he will never see WOT.

DNSTA

I think the question regarding power has been answered. Most likely your car does not produce the power required to perform 6 second 0-60 runs. That leaves us with two numbers in questions.

6 seconds and 60mph.

Since you're on the internet typing and asking questions I have no doubt that you know how to tell time. Therefore I have no reason to doubt your ability to measure 6 seconds between two events. In this case 0 mph and 60 mph.

That leaves us with 60 mph. My guess is that while your speedometer may show 60 mph you're not actually going 60 mph. Our cars are notorious for inaccurate gauges and previous owner modifications. It is not inconceivable that either the gauge is off or the gears have been changed with the necessary speedo gear change.

As has been suggested, take it to a dyno and have all of your questions answered.

You’re not going 0-60 in 6 seconds.

ForMySon

I understand. Do I need to rephrase? Assume my times are right. The speedo according to a real time cell phone app. is working properly. We checked it at several speeds. Assume the speedo is correct.

Rephrased question:
How much HP does it take to push 2.73 gears 0-60 in under 6 seconds with a 700r4 trans?
Can someone answer this please? I need a guestimate to determine what type of rebuild for the trans. The car is not ready for any track, nor is it going on the road to take to dyno test.

Project 3.4 Camaro

Trade it for one with a 2.8 or 3.1, I'm sure you'll find someone willing to trade, hell I probably would if I wasn't so far into my car already. But clearly he isn't mature enough and/or a good enough driver to have a quick car. You could fabricate a throttle stop, or restrictor plate of some sort, but imo why castrate the car, just get him something that won't get him into trouble imo. A 2.8 or 3.1 would be in the 9-10s to 60 range, If that doesn't do it, an iron duke, last resort a gee whiz.

old z mzn

iTrader: (1)

285 to 300 hp

whatever84

Not trying to be a jerk here but trust me, use a timing device like a G Tech or something similar. Granted my Brother and I cant fly a jet but we hooked his G Tech up in my car and it ran a 4.6 to 60 (tire spin was pretty bad) but about a week before we ran a 3.7 to 60 using a digital stop watch (tire spin again). So the moral of the story is use a timing device because a stop watch wont cut it, at least in my experience because the stop watch was real optimistic. Sorry cant help with the HP figure.

Mark.

ForMySon

This is what I'm gonna do. Rig the pedal so that fully pushed down is only 3/4 of WOT.

I checked the gears in the 85'. Its got the gov lock with 13:40 stamped on gears of 3.08:1. It's very possible that both have the same gears. The difference between 3.08 and 2.73 are close, maybe my spin test wasn't accurate enough to distinguish the differences being so close in gears.

Rephrased question:
How much HP does it take to push 2.73 gears 0-60 in under 6 seconds with a 700r4 trans?

What if the gears were 3.08, how many HP to push these?

torque_is_good

I caught crap when i gave junior a rebuilt 95Z with bolt ons and 1.6 rr's. he was under the car with me all the time as well as under the hood. He had "skin in the game" and he babies it. He takes it to the track to satisfy his need for speed.

2 years later and mamma rests easier as he's had no speeding tickets and no accidents (knock wood). I'm glad to hear your son is still with us. I've had friends who have lost children and you are never the same. Go hug him

Thirdgen89GTA

iTrader: (5)

Stop asking how much HP it takes to do the little things. There are far too many variables for something like this.

Run the car at the strip and have fun with it. Think its too fast for your son to drive? Either don't let him drive it, or teach him to respect it. If he flipped a car 5x and it was clear dry conditions with no outside influence then he definitely should NOT be driving it. You can have a lethal accident at 55mph on the highway with limited throttle.

I respected my dads boat, a 1960 ski boat. All mahogany wood and chrome. An antique and my dad let me take it out ALONE any time I wanted by the time I was 13 years old. He let me drive it all the time when i was a kid, barely old enough to reach the throttle pedal (yes, pedal, not hand throttle) This grew into me knowing how to handle the boat at speed, and no wake conditions.

Gearing helps, but thats only because gearing needs to be matched to the powerband of an engine. The only TRUE way to measure HP is to run it at the strip and use the Trap Speed vs Weight formula to get a HP number. Dynos just simulate that. The weight of a vehicle is the race weight, aka as it sits on the starting line with the driver in the car. The trap speed is the # recorded on the time slip.

My car is about 3750lbs with me in it and 3/4 tank of gas. At the drag strip it ran a 13.35 @ 102.8mph. The formula's say thats about 320hp at the crank. The Dynolicous app on my iPhone estimates my 0-60 as 4.7 seconds.

Which is pretty close when I plugged my time slip information into the online calculators.

ForMySon

I see. I get it. Thanks.

Tobias05

Since we're in the transmission section and all, I figured I'd humbly mention you could possibly prevent the proper detent downshifts required for normal transmission operation if you "rigged" the pedal and took out a quarter of its travel, since the 700r4's only link to the outside world is its throttle valve. I don't see the need for WOT downshifts around town in your scenario, but on the highway it is handy for the 4-3 at speed...

...How about chopping out some timing, or disconnecting the secondaries instead?

OT: Since the topic was brought up, I will have to mention that I miss flying...

ForMySon

Will dyno also identify engines redline? It will easily pull 5500 rpm, but I won't go further less I pop the engine.

Its also near impossible to do manual shifts from 1st to 2nd, the car accelerated too fast to shift it at right time.

I'm in process of finding decent speed shop to do dyno test. We're also hunting down the gear for trans to make speedo accurate.

After calculations I've determined that the car is actually faster than what I think. Whoever built this engine knew what they were doing.

Thirdgen89GTA

iTrader: (5)

I think you don't know anything for sure. You've got nothing but a seat of the pants figure. Either pay to put it on a dyno, or take it to a test n' tune. Speculation without any hard info like cam specs, heads, valve-train part#'s no one knows anything. You may find out that its just a 350TBI out of a full size van.

Red-line is primarily determined by your valve train parts, and less so but still important your bottom end. If you exceed the valve-trains ability to control the valves then you get valve float. Float is bad. The 2nd concern is how much RPM the bottom can handle before flying apart. Usually the valve train gives up long before the bottom end.

Stevolwevol

iTrader: (1)

This is true at least for gen 1 small blocks. I have seen push rods protruding through valve covers cause the springs couldn't handle the revs.

Thirdgen89GTA

iTrader: (5)

I think its true for most any factory engines. Usually the springs are good to a few hundred RPM beyond the cam's power band.

Stevolwevol

iTrader: (1)

Big blocks or I should say large bore engines bottom end can't take the centrifugal force of high rpms like small blocks.

Thirdgen89GTA

iTrader: (5)

Thats true I guess. But I bet that factory stock engines have bottom ends that can withstand more RPM than the valve train can.

Stevolwevol

iTrader: (1)

This is true. I remember back in 74 I blew my 440 (mopar) magnum due to not being able to withstand the revs I gave it and it was a factory engine. I was told that's why it blew.

abray1

Take it to the track where they have all the timers and equipment to let you exactly where you stand. My 90 ZR-1 has 430 to the rear wheels and will do 0-60 in 3.8 seconds. My iroc feels about as strong but I haven't had it to the track yet to see the real numbers. It was over 400 to the rear wheels and close to 600 ft torque.

ambainb

older thread but since when is 0-60 in 6 secs unbelievable? its a 350 with heads and a cam idles hot good chance he might not be too far off alot of cars are traping around 80 85 in mid to low 8 sec et range in the 1/8 mile thats 0-85 in 8 secs the 308s are prob helping him hook better too

89rs454

Lt1 power? Really

startat2

iTrader: (2)

I'm with the others, take it to a dyno/track. The way I see it is if you are doing a transmission anyway its time for a converter. Might as well see where the motor starts making good power to know what kinda stall you need. A dyno run and a stall is cheaper than two stalls