One of the very, very typical subjects on the forum seems to be " I have a $ 1000 and a 88 auto corvette with 3.07 gears and K&N and I want to go faster..... how ? "

And it seems many, many forum members 1st reply is "Get Gears.... 3.73's would do the trick for you"..... Do all of you that offer up this advise know something that other TPI racers don't ?? Is there a trick to making gears make a TPI go loads faster ? Do you think the person you are giving advise too would be happy if he trades his $ 1000 for a 1/2 tenth et improvement at best ?

I'm just trying to figure out the reasoning behind the advise.

thanks
Beach

 

Well...I don't chime in with the advice you are talking about, but I can say from personal experience that I've made a 5.7 TPI 88 IROC about 0.3 second quicker in the quarter going from 2.77 to 3.70 gears. Not quite the same as going from 3.07's to 3.73's, but thats a little better than 1/2 tenth.

That being said, I really don't think 3.73 gears will help much if you've already gone to a loose convertor on an L98.

 

I would think the best advise for the first 1000 would be to upgrade the exaust. Just my 2 cents

 

Best advice for $1,000 is a 50 shot of nitrous.

 

Not recently,but in the past im guilty of suggesting that mod only because Im taking it as someone who will spend 99% of the time on the street and want their car to feel alot faster then it is, as say related to track racing.

Im not seeing someone say "I want to build a drag car and what will 1,000 do for me".
Im also assuming that same person has read every catalog and seen all these Bolt on parts that gives you a 300 HP Gain when youre done.
Its alot of BS them ads.

Im also assuming the persons asking doesnt have the means to upgrade their cars at home themselves and doesnt have a significant knowldge/mechanical background on auto repair and mods and therefore will pay someone to make a change on their car for them.
So what can one really hope for with 1,000 bucks? Not much.A decent set of heads go for more then that.
The real power is in the engine mods.

Exhaust mods free's that up and gears can make or break the combo,depending what youre going to run the car for and what type of intake set up you have.
However I felt that gear mods added a good feel of power gain by putting the car in its powerband quicker on the street and where one spends most of their time driving.
Even on the highway, with steeper gears, the car takes off faster and harder then it did with the stock gears when cruising then going WOT to 100 mph.For legal driving and highway speeds,I think the stock vettes are already fast enough.

Beach made a good point last time that what works on the track will usually work on the street.I just never thought of gear mods that way really.Im glad he said that.

I dont suggest 3.73's for 1/4 mile racing on a TPI.I usually suggest someone to stay under 3.54's. or go 3.07's.
I guess one needs to define "power" when they have a grand and want to make their car go or feel faster.They need to define what theyre going to use the car for and how,etc.

One of the reasons a few years back I installed the 3.73's was because I wanted a mini-ram intake and after talking to Chris at TPIS,he suggested 3.73 with a 2800 stall for best operation.So I did the gears first.
But since ive come on the forum, ive heard a tad bit too many problems with the minirams getting them to run right.I was bummed out.Already made the gear change.
But with my stock TPI,right now,my gears feel great on the street and for passing on the highways.It felt like a whole new car after the change.

Its still the best mod i have done for the car with the way I drive it.

But we need to honestly ask the members EXACTLY how they plan to use their cars.
I also think alot of LT1 owners who have made the change to 3.73's thought it would be equally beneficial at the track for an L98 owner which is why I seen alot of LT1 owners in the past,suggest that.

This is a very good topic Beach.Hope to learn more as well here.
:)

 

I had posted earlier today that I was mad because I
found that my car has 3.07 instead of 3.54 like I was told when
I bought it, its not that it's 3.07 it's I wasn't told the truth
and didn't know it till I put a tach in it that was accurate.
my point is I've had several deep geared street cars in the last
20+ years, but never any with low 3s gearing that pulled like
this one does (my first tpi).I have studied Beach Bums recipes for the tpi
and I must agree. My car has the stock intake system save for screens
out of mas, last fri night at 1/8 outlaw track went one 8.10@83,
this was after raising shift points to 1-2@5600,2-3@5100,
this actually hurt mph alittle but et did pick up slightly.
So I will continue with my plan to improve the intake and get the
thing tuned, I have a new set of inj. to install and need chip work
in a bad way.Then I'll look at the 3.54s I thought i had.

Wayne

:cheers:

 

with a $1000 i would get an Ed Wright prom chip and a corsa exhaust your gears are just fine

 

I think that a lot of these responses are not based track experience, but are base on SOTP feel. I consider that the best criterion for street driving. If I can't feel it, I've wasted my money. Most of us never see the track and are more intrested in being "stoplight bandits", cause that is where we enjoy our cars. That can be pushed too far; ever taken a trip in a car with 4.56 gears? So, most of us make a sensible judgement call and opt for no deeper than 3.73s for the street. Dollar for dollar, those gears are the best street compromise (IMHO) if you have a tall set to begin with. Frankly, even in an automatic, I'd rather run deeper gears on the street and stay away from high stall torque converters (been there too). Any way when you ask those questions in a forum, you are gonna get a lot of opinions :D

 

Interesting responses... and all good :)

One of you above said that many respond based upon sotp vs actual track times that are tracked and sorted with traction and weather condtions taken into consideration..... I agree with this, however, the opinion is still valid, but it doesn't always tell the whole story.

I am curious to hear of accurate before and after results with a TPI and gears if anybody has any, I know somebody above reported a 3 tenth gain running the stock torque converter, has anybody else experienced such a gain, I have found after a lot of search over the years only a small handful of decent before and after tests with a TPI auto and gears, and they all had a aftermarket torque converter in the 2500-3000 rpm area... in fact if anybody has any before and after tests with any modification... wouldn't be a bad idea to start your own post sharing the experience.

As far as a lot of gear for the street.... I guarantee with 3.45 gears I am slower than my 3.07's on the street.... the 3.07's were manageable in 1st gear and I could eventually pull the gear into a hook and yet still have some rpm to work with in the gear.... with my 3.45's I may as well put it in 2nd, because 1st won't hook at all... Even when I hook up the 3.45's at the strip.... I have no additional et improvement. :( Oh well..... whadda ya gonna do !! As a note, I absolutely never race on the street though... for a lot of reasons. But I admit on a quiet industrial road I'll test my motor for testerone. :D

btw, whoever said they're not interested in a aftermarket torque converter because they've been their.... you should give the PI Vigalante or Pro-Torque a chance... these new age converters are really, really docile at part throttle on the street. You'd be surprised.

cheers,
Beach

 

Hey Beach,
Just wanted to know a few things...when you had the 3.45 gears, was this with the stock engine or the modded one?I can imagine a strong 355 -420 will easily overpower stock 3.07 gears...any steeper sounds like excess wheelspin and not going anywhere.Is it feasible that a strong modded engine will simply not need more gears as a mild/stock one may like?
Whats your thoughts on that?
:)





[Modified by Bill's86Coupe, 11:38 PM 11/10/2001]

 

Hi Bill,

I ran the 3.45's with my 383, so I was always heavily modified with the extra gear. My 383 overpowered 3.07's on the street too, but I could pedal it out of spin and still have a lot of rpm and mph left in 1st to accelerate, however, by the time I peddle the 3.45's out, I'm at the top of 1st, so I'm forced to just go ahead and put it in 2nd, and unfortunately I'm typically not at the proper mph that I should be putting it in 2nd, thus the early part of acceleration in 2nd gear is pretty weak. I think the 3.07's are a wonderful street gear. However at a 50 mph roll, I really like the 3.45's vs the 3.07's.

Regarding a strong motor not needing more gear.... in my opinion, no, a 550 hp 383 LT-1 is a strong motor, and it would respond to all of the gear you gave it. I think it has more to do with torque curve than anything, if you look at a long runnered TPI torque curve, you'll see a torque lump from off idle to 3500 rpm and these types of torque curves just don't seem to respond to gear very well, however a LT-1 which has a much flatter and broader torque curve wants the gear to accelerate quicker through the torque curve.

Here's a couple of TPI examples with gear that I know off:

1) A east coast racer named Brian Farley with a 383 SR/219/AFR combination was running mid to low 11's, and apparently at one time was a very dedicated racer. In a article in Vette Magazine a few years back he states. "I tried 6 different gear ratio's and finally settled back to the 3.07 for best performance" Forum member "Ralph" has talked to him and verified his performance opinion and experience. This guy was running solid 1.5 60's with a 3.07 and 3000 rpm converter.

2) Another east coast racer named Bob Gay, who also had an article in Vette Mag (or Corvette Fever), don't remember which one. He had a very good running heavily modified 350 Long tube runner motor running low 12's.... he installed the Ram Air and switched from 3.07's to 3.73's and I quote " I went slower 1/2 tenth".... we know the Ram air may not help much, but it certainly wouldn't hurt you any, thus I think its safe to say he overgeared his current motor configuration.

3) Friend of mine in a good running stock motored 90 vette, I gave him my old 3.07's from my old Dana 36, he was running the putrid 2.59's..... he did see a et gain, but it was less than 1 tenth on average. This was a very, very consistent bracket raced vette and a GREAT before and after test... I really thought he would have seen a 2-3 tenth improvement considering he was running what I felt was a way undergeared 2.59's..... His 60 foots are in the high 1.7 to low 1.8 with his 2600 rpm vig.

4) Me... even though I knew better, I had to find out for myself due to a personality flaw. :)... I switched to the 3.45's from 3.07's and was hoping for a tenth.... I think I hurt myself 1-2 hundredths on average, but its so close I call it a wash. I was a little disappointed with myself, I spent a lot of money with no reward. :( Oh well.... thats Hot Roddin for you.

I think gears will help you just a little bit if you're running the stock torque converter, however when given the choice to buy a good torque converter or gears.... this is an easy decision, the torque converter will give you between 2.5 -5.0 tenths each and everytime depending on your motor combination and the converter chosen. The gears on a TPI.....maybe something, maybe not.

There are a few other examples of guys with TPI auto's increasing the gear and not going any faster, however, their results are not conclusive in my eyes simply because they weren't racers out running every weekend, thus its kinda hard to quantify their results.

later
Beach

 

Todd, I feel your pain. Opinions are like _ _ everyone has one!!!!!!!
You just have to hope that the people that are asking for help are smart enough to know WHAT the correct answer is.
It's there money, THEY'LL figure it out.

 

Beach Bum,
Great thread and great rationalizations/explanations. This was a very informative and just the kind of info I had been looking for. I was thinking about starting a thread in a few weeks asking about gears (I have 2.73's and was thinking about 3.07's) v. convertor. At this point I am convinced that the convertor would be a much better investment. Thanks.

 

Definitely got to back up Beach Bum on his comments, he makes solid points and backs up with true data.

For an L98 , I would keep whatever gears came with the car. For example, Even if you have 2.59 gears, do not spend money on changing gears. You can use that money on many other mods , that will give you more power.

I am sure a gear swap will cost about $500-$600 and no gain in ET.
Is that worth it ?? :eek:

Vic

 

For a grand, I think I would buy larger injectors, 52 mm throttle body, and a set of headers. That would definely get you 50 horses.
Budman

 

GUILTY!!!!!!!!!!!!

I did gears 1st, and thought they were GREAT!!!!!!!!!!!!!!!

(from 3.07 to 3.73)

Then I added the Vig Torgue converter WOW.

I now suggest that if you already have decent gears (3.07s in a LT-1) that you should consider the TC 1st.

I think that if I would have donr the TC 1s, I would still have the 3.07s

I installed Gears.... Powereffects....and TC between visits to the track.
Those 3 mods gave me EXACTLY 5 tenths gain!!!!

MPH went from 98 to 101+..and NOT happy.

The 5 tenths gain is ALL in the 1/8th mile (from 9.0xx to 8.50x)

60 ft times from 2.02 to 1.82x)

But absolutely NO gain in the 2nd part of the run (1/8th).

Gets me to thinking that 3.07s might still be pullin when the 3.73s stop.

Motor is COMPLETELY stock.

thinking bout cam and heads now, to put some top end in it.

people say...5 tenths on TC + 3 thenths on gears + a tenth on catback!
doesnt add up that way here.

Too many people belive the advertizing... :lol:

i would LOVE to see a thread discussing advertising tactics someday. :mad

:seeya :seeya :seeya :seeya :seeya :seeya :seeya :seeya :seeya

 

Beach here's another comparo for ya. Quickblack85 copied my setup...just about every nut and bolt. The only differences between our cars is he has a vigilante vs. my protroque and he has 3.07s vs my 3.45s. We both run about the same ETs. i'm about 3 mph faster, but he's quicker in the first half. Like i said, our car are almost identical, so either the vigilante or the gears are making him quicker in the first half (my money is on the gears). With high multiple converters like these, i think the 3.07s stay on the converter longer as well staying in the torque curve longer, thereby accelerating the car quicker. Once moving thru the meat of the torque curve the gears get you to the HP peak quicker, building MPH. That would say that even for street light to street light, the 3.07s are quicker, regardless of SOTP.

That said, i absolutely like the 3.45s better on the street. I think the 3.07s kept the engine rpm too low in normal driving, especially around town. Maybe the best of both worlds would be the 3.07s with an even looser converter, in the 3200-3500 range.

 

Interesting stuff... thanks for the replys all.

Budman78,

On a basically close to stock TPI motor, a 52 mm tb will add maybe 5-10 hp, headers maybe 15-20 tops, Injectors.... I don't think any et gain would be had unless you had a problem with your stock ones. But the headers and tb would be worth 25-30 hp collectively.... which isn't bad.

Phil-tha-Rush,

Your posts makes me think a bit, and it dawns on me, the majority of forum members recommending more gear in the above scenario I layed out seems to be LT-1 owners... I'm well aware gears help LT-1 auto's quite a bit, I'd guess 2-3 tenths going from 3.07 to 3.73 gears is the norm, but keep in mind a TPI motor has very little in common with the LT-1's torque curve. What works for the LT-1 will not always work on the TPI. Just as a LT-1 would like a big lumpy cam provided the heads flow, a TPI even with good heads wouldn't like the same lumpy cam... not enough rpm to pull it off.

Ralph,

Interesting comparison, I gotta believe the difference between you and him is more in the converter and HP though.... I think he's running a bit looser converter than you, and you're probably making 20 hp over him. I'd guess your hp advantage is from the little things that you've done and learned over the years. And from what I'm seeing and I assume you agree your converter seems a little tight. As a note, my 1/4 mph was exactly the same from 3.07 to 3.45 gears, however my 1/8th mph was around 1/2 mph faster with the 3.07's..... I have a theory as to why, but I'm to tired to explain right now.

I do want to say I prefer the 3.45's over the 3.07's too.... but that is simply because 2nd gear is a bit funner on the street due to what Ralph was saying and that its higher in the rpm range for normal driving which just provides a bit more driving enjoyment.... however, if anybody is making this expensive switch to better their et's.... you might want to invest your money elsewhere. If I was to do it over again, I would not make the switch to 3.45's, however if they're free... I'd do it again. :)

Anybody on the forum with well documentated before and after tests with gears or a aftermarket torque converter.... or heck, anything ?? Please share the results if you do.... I think all of us would be interested in learning something from it.

cheerios and milk
Beach Bum

 

My 87 L-98 ran the same 1/8th mile as my 93 LT-1 when the 87 had 3.45 gears. The LT-1 gets it in the 1/4, but that is HP tak. I have seen L-98 with 3.08 kick 12's all day in the 1/4. The L-98 has some mean torque down low-4800 rpm. A 3.45 gear is real fun to drive around town in an L-98 car. 3.75 area little too much as you will run out of motor by the 1/4 mile, unless it has head and intake mods. Steve