also you have a 305 which doesn't take in as much air as a 350 which on the same intake would put more of a restriction as far as powerband goes



[quote]wow man, such disrespect from a fellow moderator. I "can't read," ok. I'm reading your crap right now oh tpi ***. Do you actually think I'm going to look at that 1 single graph and take it as gospel? For every graph you post like that, I can jsut as well back it up with another one that pulls much farther than that. 4200 rpm is absolute crap! Hell, bone stock they peak at 4400 rpm and you will want to shift past the peak once again. Since you wanna be so rude, I'll do some more math to prove you wrong. A stock 350 tpi will trap in the mid 90 mph area, lets just say 95 mph. Now with a peak of 4400 rpm bone stock. Now at that speed in 1:1 gear you would be trapping at about 4000 rpm with 3.23 gears, about 4200 with 3.42's, and about 4600 with 3.73's. Once again, math proves you wrong. 3.73's look nice again.[quote]

why do you keep looking at the peak hp as far as where you shifting shoudl be?

hp doesn't move the car it is based off torque

your shifting and gearing should be working around you torque not HP



still his ET is not proof

we need more then just ET
we need to know how many runs where made like this

there are many variables

hell I know some ppl who times vary up to .6 per run

so .2 is NOT PROOF



another thing duration on that car I wouldn't think is very streetable

also using more duration at the same lift should allow you to get away with a little more restrictive intake being it is spreading the amount of air sucked in ovr a little longer time (or so I would think)


but regardless that car i doubt it something you want to drive on the street with that much duration on the cam


also it is a 305 which again is a different beast then a 350 when it comes to air intake requirements


another thing by David @ Thunder own statement
we are talking 350 here
not a 305

 

Well. First off.

Reving past your poweband saves you bog after the gear change because of the gap true, and maybe you lose less even though descreasing the rate of acceleration after your powerband to make it up once the shift is complete.

But the better solution would be to get a tranny with gearing that matches your powerband, not pretend your car makes power at 5k. If you had some expencive gear you'd notice you slow down after 4400, or 4700 or wherever your poweband ends up until your shift point. Most guys shift before their poweband ends, and the next shift is usaully right after it starts. That way you keep accelerating.


A Stock TPI is restrictive. I've been there, done that. I spent a ton of money trying to get even my aftermarket ported TPI setup to rev. Just didn't happen. The farthest best I got my motor to rev was 5000rpm. Although technically it made a little more power at 5500, the rate of increase was soo minor it made no sense other than to shift at 5000.

Only thing that moved my powerband up was the blower.

Now, set asside TPI and look at the stock L98 cam.

Lift: .413 / .428
Duration: 202/207
114.5 * Lobe Separation

Even with a carb and a nice single plain manifold, that cam's only good for 4500. At 5000 rpm you make about the same HP as at 3500.

Even with the 1.6RR's (changing the lift to .440/.456) it doesn't help the powerband move up any, it just ads 3-5hp.


Another thing to note. Without comparing the time slips from both runs, and comparing the atmospheric conditions of both days its almost impossible to say if the 3.73 hurt or helped him. He might have a better e/t, but his MPH may be down. Or maybe he shifted at 4500, and his tranny flashed to 5k because it slips? Who knows.

We don't even know what size his tires are. He could be running 28-30" tires for all we know, and with that size a 3.73 might be the right ratio.

-- Joe

 

There are some very good theories here, but I guess not many of you have experience or knowledge of the Superam. This setup with the base has been proven to make an extra 61 LBs of torque at 5800 rpms. This formula with the 3.73s is right on track, this cars powerband has significantly been altered from a stock tpi setup which has trouble getting to 5000 rpms, let alone making any power there. The user states that this car has 1.75 inch diameter headers, no cats and 3 inch exhaust, so there is no exhaust restriction holding this engine from operating efficient at high rpms. Also this user has installed 1.6 ratio roller rockers while not a large difference from stock this has also slightly changed this engines powerband. Mileage on this vehicle is not stated but I am sure a new set of valve springs are in order, stock springs are weak and for a car that will now be working the upper rpm range much harder you are asking for trouble. Ask the wife for a set of heads and cam for Christmas, with all the mods done I think you would be extremely happy.

 

My 82 Z28 with a 305 TPI picked up .49 in a 1/4 mile with Herb Adams solid control arms.

Do you think I should:

A: tell everyone they should do the same?

or

B: be considered a liar?

the answer is "C"

C: listen to some other guys that have gone way faster than me and owned about half a dozen more thirdgens than me, before I run around telling them all to "just change to this or that" or some other slower new guys to just "do this or that" because it miraculously defied logic and works just once in a while (3:73's).

PS: Please refrain from name calling, specifically referring to people as stupid, whether or not used with inuendo. To see you use "stupid" to describe anyone but your self is so ironic it defies my ability to refrain from laughter.

thank you

 

thats the profile for the 85 - 87 & 90 - 92 TPI cam. for some reason in 88 & 89 they used a different cam. here are the specs:

Lift: 415/430
Duration: 207/213
LSA: 117*

considering the car in question is an 89 and has this cam, he should make peak power a bit higher than a car with the smaller TPI cam

 

-thanks for pointing that out to.

 

If the cam had a 114d lobe seperation than yes, however the 117d lsa actually moves the powerband down to 4k.. (maintaines the same hp til 4500, than drops sharply after)

That cam would prolly work really well with a blower though.

Everyone forgets about lsa/centerline..

-- Joe

 

Couldnt race this weekend because of snow

 

My 3.73's work really well with my stock TPI. I have no times yet but it pulls hard all the way to about 120mph and then is a little slower in acceleration but still pulls to about 135-140mph.


-Oh and i think if you get a good launch you'll take him.

 

Thank you! You helped us prove that 3.73 is the wrong gear for TPI.

With your 700R4, 120mph is 4212RPM with stock tires..

130mph is around 4600rpm, and 140mph is 5100rpm. The fact that you see a loss in acceleration after 4200-4300 proves your outside the power band, and 3.73's are wrong for N/A TPI.

-- Joe