87draggta

I was kinda of curious what would it take to get my car into the 6 sec 1/8 mile range. I ran a best of 7.23 with a 1.43 (on spray) 60' at 90 mph. I'm runnin 10.2-1 350, dart 215 pro 1 platinum, lunati voodoo 560/580 241/249 duration hydraulic cam, msd 6-al, perfomer rpm, 125 shot. Turbo 400, 3800 stall 750 holley, 4.56 gear and 26X9X15 hoosier slicks, car weighs probably 3100 pounds. And really crappy shortie header I don't know what they are but they have 1.5 primaries into like 3 feet of 2.25 pipe and dual flowmasters. I shift a 5500 and go through the traps at 5800, and an entirely stock suspension, less front sway bar

fast82z

iTrader: (1)

My guess is that exhaust is KILLING you. I had a similar setup a few years ago using a 246/254 .558/.558 112lsa hyd. roller cam, trick flow 195 heads, dual 3" exhaust, 3.73 gears, and no nitrous for the big differences from your setup. That way ran 11.44@ 118 without nitrous, and you're looking about 11.3 for the 1/4-mile. I bet at least a dual 3" exhaust if not that with long tubes will fix you right up. Also, try shifting at 6000+rpm. That size cam I wouldn't think hits peak power untill at least 6000rpm to make 6500rpm a far better shift point.

87draggta

Yeah those headers were on the car when I got it and I already had the mufflers. I was shifting so low just to be safe, I don't want to kill something my crank and rods are cast. which I know that 6500 wouldn't be hard on it. I just like being able to go out and run faster than a few of the guys in town with 20K in their car, especially when I only about 4 in mine. Long tubes are on the list though, I'm just afraid that 1 3/4 primaries may be a bit too big

Fast 383

iTrader: (2)

200 Shot? And drive the car to it's peak power, stop cheating it.

fast82z

iTrader: (1)

I'm not that worried about the headers so much, it's the 2.25" pipe after them that's the really crappy part.

87draggta

I was just running open shorties which were too loud and apparently didn't have enough back pressure because when I put the exhaust on it seemed to run lot better

bart91406

1 1/2 primaries are for the 305 in grandmas car,They are absolutely killing that 406. Get some hedman 1 5/8 if ground clearance is not a big issue, or some 1 5/8 mid-length pacesetters if you need to hit a speed bump occasionally.1 3/4 primaries like the hooker super comps would be best on a 406, but I do not see that they will be enough better than the hedman long tubes to justify the additional 400$.

Time2Fly

7.23 @ 90? Is the mph a misprint? Tighten up the convertor.

87draggta

Nope not a misprint it was like 89.3 or something like that. I don't know if it makes adifference or not but it launched hard and just a few feet past the light it lost all traction kicked sideways and spun pretty good until i hit 3rd. It is a 355 not a 406 If I put a 406 I messed up. ground clearance doesn't matter. I was going to put a good set of headers on the car, but I put the shorties onto get it running and never changed them.

1BADRZ28

iTrader: (2)

Something odd about 1.43 60' and 89.3 mph in the 1/8th. That 60' is a crazy number for running a 7.24. I ran 1.39 on a 9.69 pass.

Orr89RocZ

iTrader: (20)

Thats teh first thing i noticed. 1.43 is MOVING. My nitrous 383 has gone 6.7's with a 1.41 and 1.45 60 foot. Your combo should definately match close to that. Should be high 6's at close to 100mph i would think

Bump to a 150 shot, get traction and you should match me atleast, and GET NEW EXHAUST

ALSO definately shift that thing at 6200-6500. That a roller cam? Lift is awfully high for a flat tappet. That cam is a touch bigger than the 1 i have in my 383 and it peaks at 6250 rpm. I shift 6500. I'd do the same on that setup for sure!!

87draggta

I went and dug up my time slips and I was wrong it was a 1.49 60 ft,7.2852, and 89.44 mph, which was my first and only N2O pass so far. My best motor pass was 1.71 60' with a 7.93 at 86.53 mph. My car seemed to die up high with the Nitrous, but down low it felt good. I thought the mph difference would be more than what it was. I'll try and post the slips, my cam is a flat tappet (I have 1.6 roller rockers instead of 1.5), i guess i figured the lift right here is the link to Lunati's website,

http://www.lunaticams.com/Product.aspx?id=1986&gid=287

Hydraulic. This is possibly the most powerful hydraulic cam ever designed! Designed for Very Hot street/bracket race applications, this cam requires a minimum of 10.5:1 compression, 4.11 gearing and 3500 RPM stall converter. Works with up to 250HP nitrous, and pulls Very Hard past 6500 RPM.

• Advertised Duration (Int/Exh): 284/292
• Duration @ .050 (Int/Exh): 241/249
• Gross Valve Lift (Int/Exh): .525/.546
• LSA/ICL: 110/106
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: 2500-6600
• Includes: Cam Only

Orr89RocZ

iTrader: (20)

i think its the exhaust thats really hurting as nitrous adds alot of cylinder pressure and that excessive gas volume has to go somewhere. With tiny pipes, its a restriction for sure.

Extend the shift rpm and get that traction problem sorted. It should pick up alot

86 on motor is pretty good, but on a 125 shot, it should hit mid 90's

87draggta

Yeah I'm trying to scan the slips, but they just aren't turning out real good. Yeah i was super pleased, especially since i was expecting like 8.50's or so on motor. It may weigh less than what I think that it does, and the suspension the only modification to the suspension is 20 years worth of being ragged out. Would the headers really make that much of a difference? I could understand if they would because I went from an 8.13 to 7.90 just by letting 2 pounds of air out of the tires. I'm just afraid i'm going to hurt the cast bottom end running it much past 6, which that is what chip is in my msd box

Orr89RocZ

iTrader: (20)

what kind of cast bottom end? what rods and what rod bolts?

shift at 6200 atleast should hurt much but many guys have done 6500 with decent cast stuff

AlkyIROC

I was spinning a 383 with a cast 400 crank, factory 400 rods and rod bolts and cast 350 pistons to 7000 for 2 years before I finally broke a piston.

You need at least 1-5/8" headers. 1-3/4 with 3" collectors would be better.

You're short shifting. That cam should work to at least 6600. If the car is nosing over at high rpm, you have a lack of fuel problem.

Your low MPH could be because you're using 4.56 gears and 26" tall tires. With that deep a gear, try 28" tall slicks.

Time2Fly

Do you know what the bottle pressure was after the pass? Low bottle pressure can cuase the car to really run out of steam on the big end - piston crowns really hate all that extra fuel - we have lifted the top ring land because of that exact same issue.

Do you have the 330' time? That can tell you how well you were making power at half track. With a 1.43 you should be close to a 4.20ish at 330'

I think if you get steady bottle presssure throughout the pass you may be in the 6s on your 125 shot.

On the spray, I think your motor might like the larger primary headers and a tighter converter.

DIGGLER

iTrader: (1)

Something is wrong for sure. its not making squat for power on topend. my LS1 car went 7.4 @ 93 with a 1.53 60' on motor with m6 trans. 376rwhp.
my LT1 car runs 7.teens-7.20's @94-96 with a 1.55 60' on motor. (more of a nitrous converter) made 370rwhp through th400/9" rear/28" slicks and is lighter than LS1 car.
so, in my eyes, your spraying the car and its making less than ~370rwhp down the track. does not jive with your mods at all. coming off the line it looks ok, but the mph is nowhere near right. you should pick up 6-10mph with that shot, not 3. whether or not the header size could screw things up that badly i do not know. but something is not right.

87draggta

I'm not sure about the bottle pressure, a lack of fuel pressure is possible. I'll have to dig my slips back out to check my 330, I plan on going to a 28 10 slick when these wear out. Its winter so I figured that I would do a few things and try to get it into the 6's in the spring, but if it don't whatever, by the way thanks for the advice

DIGGLER

iTrader: (1)

dont know how much the car weighs, but i would think you should be running 6's n/a with the stuff thats in that motor. (unsure about that cam, though).

87draggta

I don't know about running 6's NA, but I agree with you that the mph gain is screwy. Any suggestions as to what it may be? the car isn't really launching all that hard, but it starts to really make power right after the launch. The converter flashes at about 3k on motor and 33 on nitrous, but the car doesn't seem to be moving good until about 4K then it really turns on, and hits 5500(were I have been shifting it) real fast. Like I said it's only turning 5800 rpm through the traps.

AlkyIROC

Since you're only running 1/8 mile, what gear are you in when you cross the 1/8?

87draggta

Yeah 1/8th. I'm usually in 3rd by the end, its a Turbo 400

DIGGLER

iTrader: (1)

with a stock LT1 and nearly stock heads and the following, my car went 7.19@98. 1.54 60'.
230/236 .544/.555 112 hydro roller cam
hooker longtubes w/3" bullet mufflers
single plane
th400 w/ ~3600 converter leaving on footbrake
9" rear with 4.56 gear
28x10.5x15 hoosiers
raceweight- 3100# with me in it. 35x rwhp.

with a 80rwhp shot of nitrous, it went 6.60's @103.

my suggestion is to get the car on a dyno.

Shagwell

The headers and itty-bitty extension pipes are definitely a large choke point, especially on the squeeze. Past that how's the tune(timing/advance, jet sizing, how do the plugs look)?

As for launching hard and then unloading the tires, what's on it for shocks? The 20yo wore out stockers?

Something is definitely not right.

Also, not that it's the problem, but a 215cc head is a bit large for a 355, especially at that low of rpm. Even at 6500, still a lot of head.

mattsv8_03

iTrader: (2)

you need bigger headers, larger solid cam. and a better 60 try getting down into the 1.38 range and more mph from the heders and cam.

87draggta

I have no clue where the closest dyno is, I don't think there is one for about 4 hours from here. As far as jetting goes I kept reading the plugs and changing till they looked good, it has squared 75's, and on motor the timing is locked out at 36 and on nitrous 29. Yeah stock shocks/struts. I am in the process of putting a roll bar and sfcs, and I bought some trick springs to put on whenever i can afford some 90/10's and I was planning on changing the back shocks to a 50/50 all at the same time. then eventually an adjustable TA and all that other junk. But I'd rather put my money in where it matters.

Orr89RocZ

iTrader: (20)

For about 275, you can get a wideband o2 sensor and a air fuel gauge and constantly monitor your air fuel ratio and tune with it. Much easier than plugs and more accurate too.

Any car using nitrous and such should have one i feel. I tuned my car with it on the street and when i went to the dyno i only picked up 10hp or so at peak.

brandoz28

iTrader: (1)

one of my friends went from 8.20 to 7.60 going from flowcrap 1.5 shorty headers to the hedman 1 5/8s longtubes. that was on the motor with a th400 and a 355 with iron eagle heads. exhaust can do a LOT

bluegrassz

iTrader: (3)

Were in Kentucky are you located? There should be able to find a dyno shop in Louisville, Bowling Green, or Lexington.

I went 7.64 with a stock bore L98 pistons/rods/crank with heads, cam, intake and carb swap. Im running a Comp xr282hr cam and dont shift untill 5800 or 6k myself. Thats with 3.73 gears and a TH350 with a 3500 stall.

87draggta

Yeah probably, i'm about an hour away from you, but I'm not going to haul my car up to a dyno. There's probably one in knoxville if I looked hard enough. I was there at London I only made it twice last year a bunch of us rent the track in the spring and fall.

Fast 383

iTrader: (2)

Sounds to me like your 3800 stall is becoming a 4500 stall with the added 125 HP. That is most likley the MPH problem especially if your short shifting the car below it's peak power. The other stuff is a little mismatched but driving through a converter will definelty nose the car over on the top end and leave MPH on the table. That would be the first thing I would change if you plan to continue spraying the NOS.

bluegrassz

iTrader: (3)

I had hinted around to Craig at the track to have a dyno day. Find someone with a portable dyno and have an event.

There is a guy a few miles from my house that has a engine dyno, but no local chassie dynos.

You might try www.ptcrace.com for a new converter or have yours redone.

87draggta

I like the track at london, and the owner seems to be pretty good to deal with, that would be about the only way I would do a dyno, really I can't afford it. But anyway I am hoping t be able to start a little earlier this year, which really depends on whether or not I get my cage, lexan, and finish repainting before the track opens. do you usually go to TT or the brackets on sat?



Well fast LS1 I never thought about that, but I don't think that it launched that high, which I'm probably wrong it very well may have. That is definately something i'll look into.

bluegrassz

iTrader: (3)

I go to both TT and Sat. Depends on whats going on. Since they started the 1/4 mile street race on fridays, I have been going more on fridays.

87draggta

I had been going to Knoxville when I had my impala, then I went to London and the track is so much better.

bluegrassz

iTrader: (3)

Yeah, I get 1.61 and 1.63 60ft times with my Hoosier QTP's. Its great when they spay VHT and the Quick 8 cars are running. Its a nice 1/8 mile track with 1200ft elevation.

87draggta

i have had a few people talk about tightening up my converter what does that mean? it is supposed to be a nitrous converter, with the anti-ballooning plates and junk. someone commented on the size of the heads, I was planning on building a 415 or 421 and went ahead and bought those so I wouldn't end up buying two sets of heads.

87draggta

Before this thread gets too long and pointless, I have gathered so far that I will possibly need(these are most the things that have been listed),

Bigger headers/ exhaust
Perhaps a different cam or converter
some way to monitor and control bottle pressure
taller slicks
a better fuel delivery system
Perhaps some suspension upgrades

Orr89RocZ

iTrader: (20)

you run a bottle heater correct?

anyway a tighter converter to me is one that stalls less. Since your on nitrous, a regular 3800 stall may stall at 4200+ and that may be abit high for that motor. May way to get one custom build for that motor, something that will stall around 3800 on the nitrous, 3500 on motor.

joeblue83

iTrader: (8)

I went from a dented up 3 inch single to the same exhaust but with a 3 inch cutout after the y pipe the time went from a 12.9 to a 12.03

DIGGLER

iTrader: (1)

hes getting a 1.43 60' on the nitrous, which is pretty decent -about 2 tenths better than on motor which seems about right to me. i wouldnt worry about the converter at this point. looking over the parts list for the motor i feel like it should be making lots more power that it is. 89mph is way off the mark, imo.
next thing i would change on the car is the headers. aside from that, if the heads are ported, they may be ruined by bad port work. or, maybe the cam/valvetrain has issues? a dyno with wideband could tell you a LOT about whats going on.

87draggta

The heads are out of the box no port work, from what i remember the converter wasn't stalling much higher on the juice like 3 or 4 hundred more rpms. I gues you all talked me into changing my headers, that is going to be my next money spent after I get my car back together. There hasn't been any metal in the oil, so i don't think the came is wore down, but what other kind of issue could it be? I know that the cam was installed right.

DIGGLER

iTrader: (1)

just thought of something else.... you said it was a nitrous converter. if its expecting a 434 with a 300 shot, it will not work well with your car. it may never get locked up at all which could be the case. its not BAD, it just may need more oomph than what your able to throw at it right now. seems to start working on the juice ok, so this scenario is a possibility.
a friend of mine had his car on the dyno several times and it was making ~400rwhp and never got the nitrous converter locked up throughout the pulls. he swapped in an n/a converter and made another pull and the car picked up 150rwhp.

87draggta

That may be, it is a Jegs torque. everyone around here has had good luck with them so I figured that is what i would get. It is their 35-3800 with the anti ballooning plates. I know a torque can make an unreal difference. One of my buddies has a 79 rs with a 406 and was running 7.30's with a 3500 boss hog, junk, and had a terrible vibration at the top end of the track and around 40 mph on the street. Someone mentioned to him that it was the torque, and all he had was a stocke rto go back in and with the stock converter he was leaving the line at like 1700 but went from 7.30's to a 6.69 off the trailer without a stall. But he has one heck of a motor.

Shagwell

Never change a bunch of stuff at one time, you'll be chasing your tail to figure out what worked and what didn't.

I'd do the exhaust and turn it up to around 6500 and see how it acts.

Short-shifting on a moderately stalled converter won't tell you how it's working/not working. Like DIGGLER said, .2 in 60' on the spray would make me think the TC is doing it's job. Possible top-end slippage could easily be due to the short-shifting. - Since you said it is just a Jegs 35-3800 w/ the anit-ballooning, you obviously don't have a custom one spec'd for your planned engine, thus it's not too bad.

As for the heads being a bit large, they really shouldn't be hurting you with that kind of stall and the jug. Not optimum, but fine for what you're doing and will leave you that room to grow(been there, done that).

Definitely get sfc's and the cage. That way you're not chasing your tail due to chassis flex.

...to sum up my reccomendations;
- bigger headers & exhaust(prefferably long tubes and 2.5'+ exhaust)
- subframe connectors
- cage
- turn up your shift point and have fun!

z28freak84

What he said, open it up, and TURN IT UP! Shift that bitch at 6800 and let 'er eat... That thing should run 7.20's at 94-96mph OFF the jug.

87draggta

the track is closed till spring. I'm not planning on spending anymore money, other than my lexan side windows so i guess well what will happen then.

brandoz28

iTrader: (1)

headers and an exhaust would be a MUCH better investment than lexan windows. like everyone else said, that thing should run on the motor where its runnin on squeeze. a little money in suspension would be a good idea as well