69 Vette

Cool! I was thinking mid to high 13's. If i pulled a low 13 i would be thrilled

ajrothm

It really depends on how well you hook and how quick it starts to make power. Chasis setup, gearing and driving skills play a big role as well as vehicle weight. I mean early 90s 5.0 Mustangs easily run 12.50s@108+ with only 240-250rwhp but they are light(usually 3200-3300lbs w/driver), have steep gearing and a GREAT chasis and suspension for drag racing. Same thing for the 02-04 Z06 vettes, they make 350-360rwhp, weigh around 3250-3300lbs w/driver and are geared really low.. They run 12.0s@116-117 stock..

BUT I have heard/read those ramjets are not making the power they advertise. I do know our ZZ4 averaged 255rwhp going through a M22 4spd and 9" ford with 4.11s. That was with headers/2.5" exhaust w/ 40series flowmasters and a 750 vac sec(3310), timing at 36* total.

Glensgages

E.T. is a function of how-well you are using (via chassis, gearing, TQ-multiplication, traction, etc. ) the available HP & TQ and getting it to the pavement, while MPH is indicative of available HP to weight of vehicle:
I know of a full-interior, un-butchered mid-'70s Corvette, with a stock ZZ502, power-sapping THM400 & a 10" converter, 3.90 gears turning 29" slicks that runs 12-flat (12.003 ) at 'just' 112 MPH, simply because it 'works' well, and runs very-good 330' and 660' times.

I believe Isosceles, who bought GSC3's 383, ran 109 MPH @ 12.90s, with a tight converter, no real gears (3.36:1 ), and rock-hard BFG T/A Radial tires, yet my heavier Z28, with a 355" SBC that makes 'maybe' 420 HP, would run 12.70s if I didn't deep-stage the car (it runs 12-eighties deep-staged, with very-little roll-out ) at 'just' 105 MPH:
the Z28 has an 8"/4500 RPM stall-speed converter, 4.11s and 28" slicks.

ajrothm

Glensgages, I agree. You can run good numbers with little power if the setup is right. I can see a ZZ502 going 12.0s in a heavy chevelle. Ofcourse I HOPE it would but the facts are...Stock 502s are turds. IF, and I mean IF its actually making 500 crank hp, he is probably barely getting 350hp-375hp to the wheels hence his low mph (112). He just has the right converter and gearing combined with strong low end torque so he 60's and 330's well.

I had a prime example in the same areana, I had a 78 Trans Am with a 10-1 406" pontiac. It had 69' GTO heads with light porting, a hyd flat cam 231/239*@.050, .485/.507 lift. With a 3200 converter and a 3.42 gears it would run 12.0-12.teens at only 108. If it made 400-425hp at the crank I would be suprised. The car weighed 3650lbs with me in it. It would leave really good, often 60's were 1.62-1.65s. It was all front half, 7.60-7.70s@89 in the 1/8.....Not much after that..LOL It was a lot of fun though. I want to get my vette to run that good on the front half with about 7-8 more mph on the back half.

GrandSportC3

No doubt.. It all depends on how effective the setup is dialed in..

I've beaten cars with 200 RWHP more than my car because they weren't setup properly (even though they were running on slicks)

69 N.O.X. RATT

Approx. 2250 lbs race weight.
980-1020 hp. depending on nitrous tune. 454 + 400 shot
Best 60' 1.130
Best 660 (1/8) 5.09
Best mph in the 1/8th 137.29

Like Oliver I am doing a new motor (heavy nitrous 555). I am hoping to go 7.40's in the 1/4.

frostbitten09

I ran 15.146 on my bone stock l48 78, next time i will run 14.8's. Its all pure stock l48, higher octane gas,

OzzyTom

I put the 68 vert on a weighbridge yesterday....
1620 kg
that's 3570 lb without me in it !!!
Add 210 lb and I'll be at 3780 lbs in street trim.

With that weight I reckon I'd need at least 340 rwhp to get into the 12's


I think I'll need to put myself and the vette on a diet....

So where does one shed weight off a vette, without sacrificing all comfort and functionality for dual purpose street/strip use ???

Obviously dropping the spare wheel and jack at the track is a no-brainer..
Keeping fuel level in tank to about 1/4 full is easy too...

But what else would make a reasonable weight saving, and how much could be shaved off.....

I was told by someone that for every 80 lbs shed, ET will improve by 0.1s.
Alternatively, increasing power by about 10hp , will also improve a time by about a 1/10 second.

I'm beginning to think I should have orderred a few more neddies to overcome the TH400 inefficiency.

GS, the TH200-R4 is not a common box here in Australia. It is also considered by many as a light duty box.
The Th700-R4 was used with Holden models here in Oz, so they are more readily available, and parts and knowledge on prepping them is available here.

Might just run the TH400 initially whilst running in the motor....
Then get some dyno figures of power and torque, and get some baseline ET data.

I'll then be in a better position to decide whether I'll need to spend money on chassis, gearbox, further power mods, or all of the above.

tom

GrandSportC3

I have no idea why your car is that heavy.. '68 Convertibles were abou 3200 lbs from the factory..

Here are a few weight savings tips:

1) wheels & tires (lightweight wheels and bias ply tires with skinny front tires will save you over 100 lbs rotating mass which is worth over 3 tenths on the drag strip!!
2) composite rear spring (30+ lbs saving)
3) either race drivers seat and no passenger seat (just for racing) or late model '80 - '82 seats (much lighter than stock '68 seats). With the single pastic race seat, you'll save 70+ lbs right there. A Summit race seat is about $70. It's easily installed and can be changed back to stock seats in minutes..
4) no spare tire carrier + spare tires (70 lbs saving)
5) aluminum heads (50 lbs saving)
6) Aerospace drag brakes (about 100 lbs weight savings (front and rear together)
7) remove heater system
8) aluminum radiator
9) remove wiper motor

There's much more weight savings potential without hacking up the car...

OzzyTom

Yep...
I was astonished when the operator said 1620 kg !
~ 100kg more than I expected.
I might try another weigh bridge.

The new motor has alloy heads, so that's a step in the right direction.
I was thinking about replacing the radiator to ensure no probs with a new motor, so an alloy rad sounds like a good idea at this stage...
With removal of the spare, I guess I've got about 150 lb's total saving with these mods. That should knock off about 2/10ths.

GS: thanks for the info

tom

OzzyTom

What is the view of forum members here....

Given the same vehicle and power plant, what is quicker.....

A manual transmission or an auto?

I understand that a stick shift is more efficient, so there'll be more power available at the rear wheels.... but a tricked up auto trans with a 3000 rpm stall can get off the line and make quicker gear changes....

My daily driver is a turbo-charged ute with 400 rwhp.
There are guys here in Oz with same mods as me who have ~440 rwhp in their 5sp manual equipped utes due to less losses in trans.
But I can consistently run quicker times than them.... almost a full second. Main reason is I can maintain boost pressure during the gear change, and therefore maintain higher average power to the ground. On the manual trans equipped utes, the boost pressure drops significantly during gear change, and it takes a bit more time to come back up to full boost.... part of the ECU programming I believe.

But what about in our C3's.....
If comparing a C3 fitted with a 383 and a 5sp manual (eg Keisler TKO500) to a
383 fitted with a 3000 rpm stallie & shift kitted TH700-R4, what would be quicker over the 1/4?

just curious......

What are your thoughts?
Has anyone made any back to back comparisons?

cheers

tom

69 N.O.X. RATT

A clutch car is quicker ONLY if the clutch is properly tuned. 99% of drag races can not tune a clutch to outrun an auto with a good converter. If autos were faster you would see them in pro-stock....even those guys miss the clutch set up sometimes. Often times when you see two pro-stockers run the same mph, but one is 2-3 .00's quicker it is in the clutch tune.

OzzyTom

OK NOXY....
So you're saying a typical well setup auto would be quicker than a typical manual trans?

The reason I'm asking, is, I would consider putting in a manual if it was definitely quicker. They are more fun to drive through the hills too.

The major problem for fitting a stick shift is that I have a right hand drive vette, and the footwell is narrower on the right side.
Adding an additional (clutch) pedal leaves little room to rest one's foot on the side. Also the bigger 16" steering wheel on the '68's sits quite low..... As it is at the moment, I reckon my thigh would be hitting the underside of the steering wheel with every clutch depression.

might stick with the initial plan and stay with auto for now.

ajrothm

OZZY, autos are DEFINETLY quicker... In a street car with regular clutch and transmission(ie. not a adjustable slider-type clutch, race tranny-Gforce, Lenco etc) a good built auto with the CORRECT stall speed will always 60' and DEFINETLY 330' quicker then a stick car. The auto car get into the powerband quicker, torque is multipled through the converter right from the launch and super fast shifts. Plus the stall speed keeps the engine up in the powerband after shifts. BUT yes, they do dyno much less rwhp and will run much less MPH in the traps, you just get there quicker.

Not to mention stick cars KILL parts and most people can't drive em well enough to get repeatable quick ETs.

I know, I have an LS1 car with a 6spd and I get killed by autos at the track all the time, some of which make 50 less rwhp. Thats why I bought a C3 with an auto, I knew what I wanted to build with it.

Gordonm

I put in a 385 stroker last year but have not run it at the strip yet. My old 350 which I estimated at around 420 HP crank ran a 12.7 at 110 best. The car weighs in at 3150. I didd dyno the new motor and it was at 409 RWHP so Ishould be able to get low 12s or high 11s if I can hook it up. The specs are in my Sig.

GrandSportC3

Stick vs. Auto depends a lot on the driver..A good driver (with a transmission with the right gear ratios) who is launching hard (4000 - 6000 RPM launch) and power-shifting will always beat a auto car with the same setup otherwise.. A manual transmission will give you better RWHP due less parasitic loss (approx. 5% more RWHP on a stick car).
I've run 11.67 @ 119.79 mph with my 5-speed. The same engine ran 12.90's in a auto car with a street converter and would've maybe run 12.50 with a good converter. The car was about 500 lbs heavier than mine, so the best possible with the same weight would've probably been high 11.s or low 12's.. still 3 to 4 tenths slower than when I raced with that engine with the 5-speed...

However, if you are using a Muncie M-21, the auto will be faster as the gear ratios of the M-21 are for road racing and not drag racing. The first 3.27 gear of the TKO really helps to get good 60' times.. Even with a good converter, it's difficult to get those kind of 60' times that I got with the TKO.. There aren't too many cars that are getting 1.50's 60' times with a 465 GROSS HP engine on a C3... Most of them are happy to get into 1.80's...

69 N.O.X. RATT

In cars (properly set up race cars) into appox the low 7 second range the autos will 60' better, by 330 the clutch car has passed by. Remember though I am talking about properly set up race cars with racing trannys and highly tuned clutches.

In a street car with the average driver the auto will usually be quicker (e.t.) but usually down in mph.

The tq. multiplication advantage of the auto is gone by 30 to 90 feet.

OzzyTom

AJ... a feather weight C3.... Nice lookin' vert.... those rims have obviously shed a lot of the weight.
I think if you've got 409 rwkw you should definitely get into the 11's.
When do you think you'll get the opportunity to run it?

tom

GrandSportC3

feather weight? My blue/white '68 weights 2750 lbs (without the nitrous) and I have a full interior except for the passenger seat. It still looks like a street car except for the scoop
With a full nitrous bottle, a 3 gallons of 112 octane and me in the car it weights in at about 3000 lbs..

ajrothm

Yeah the old auto vs stick debate has gone on forever and will continue to go on forever. I think on cars that make less power(like under 300rwhp) a stick car will run quicker assuming the chasis works, gearing is right and the driver will actually drive the car. This was the case back in the 90s when we were all racing 5 liter mustangs. A stick was the ONLY way to go. The AOD sucked period, especially in a 250rwhp car. A few guys went C4 but there was just not enough HP to run it.

My point is, in the average street hot rod, especially in a heavy car like a C3, the auto with the right converter will USUALLY beat the average stick car. Here is a couple reasons why ASIDE from the ones I posted above.

1) C3 drive trains are weak and VERY FEW people are going to be dumping the clutch from 4-6k, at least not many times. LOL
2) Most will not be able to get the stick cars to hook without a lot of suspension work that most street cruisers won't have. Stick cars shock the drivetrain/tires a lot more.
3) Gotta have the gearing to keep the engine from bogging after the clutch dump. Big cams, weak bottom end power SUX for a stick car.

No doubt a stick car will make more RWHP and run more MPH but with engine mods being equal, with typical street going hardware and drivers, 9 times out of 10, the autos are quicker if setup right.

My LS1 car makes 400rwhp, has a 6spd and 4.10 gears, I can't completely side step the clutch on the launch because I still have a 10bolt rear which is weak but I have done some pretty hard 4k drops and it has NEVER 60'd better then a 1.78. All my friends with the EXACT same parts(cam/exhaust/tuning) that have autos make about 360-370rwhp yet run OVER 5 tenths quicker then me. My 60's and 330's (especially the 330's) are really killing me. THATS where the stall converter really helps is in the 330'.

I have gone through this stick vs auto thing so many times with so many of my cars and I have firmly decided I will never build another stick hot rod again unless its just a cruiser for carshows/weekends etc. They are just too fragile and inconsistant.

I am following GSC3's lead and going with the Art Carr TH200R4 and custom 9.5" converter. It will still lock up on the highway which will be great but more importantly it will 60' and 330' like a ***** with 2.74 1st gear and a big stall.