big dave

Alot of you guys have responded to my other thread in this section but not everyone believes my times were possible with me short shifting. My questions is, at what rpm do you guys shift your bolt-on cars?

I'll go first. I was always told that shifting at 6200 was the way to get the quickest et's with these cars. My previous best was a 12.40@112.8 on dragradials using that method.

My new best...12.27@113.4 on street tires, shifting at 5500 (possibly 5700 with these inaccurate tachs).

Has anyone truly experimented with lower shiftpoints?

I'm sure the 4.10s have a lot to do me getting away with the lower shiftpoints. I really don't think it would work with a car with 3.42s but may be possible with 3.73s.

connexion2005

iTrader: (49)

I argued with you a bit about it but I really don't know. The thing is when I **** at 6,200 I run out of 4th gear 15 feet before the traps. Had I short shifted it like you I would have finished the race with maybe a better e/t or trap speed since it didn't slow down of rev limiting. It's kind of in the air for me. I'm going tomorrow evening and launching all out and going for low 12's with a limiter set @ 6,500 still on the stock tune though. I'll let you know. Also what size tire are you running? I'm running 275/40/17 e/t streets...

big dave

I'm running the same size tire. I was short shifting because of the valve float issues I was having. Who knows what I would've run shifting at 6200 that particular day. Now that I have the new valvesprings, I plan on finding out exactly what works best for my car. It sounds like we have pretty similar setups, I'd almost bet that your car has the potential to be quicker than mine in the right conditions. Can't wait to find out what your car will do tomorrow. If you do get the chance, try experimenting with the lower shiftpoints just to see how your car responds to it. Best of luck to you though. Hopefully you get yourself a new best.

camarokid94

iTrader: (2)

i agree i with the short shifting. back in my old bolton days i was running 12.6s and they guy i worked with (who has a 7sec car) told me to try adj my shift points i told him my peak on the dyno and that i tried to shift about 200 or so after that. he said try lower as it may put me closer to the MEAT of the torque curve. i did (about 5800 ish) anb i dropped to a best of 12.42 and i was on my way to a 12.3 but i let off as i was bracket racing.

so in short i suggest tryin all diff shift points to find you best.

3DFORMULA

iTrader: (4)

I speed shift at 5700rpm on the stock tach which as we know may be wrong.

LS1crazy01

iTrader: (14)

Hey dave Im just curious are you in 4th or 5th gear crossing the line? By the way I shift at 6200 RPM as well.

DKITCHEN

iTrader: (10)

Big Dave, your car has pretty much the same mods as me so I'm hoping for a good time like your's this Sunday at MIR. Are you running this weekend? BTW, I have my shift light set at 5800 so I'm sure that I'm in the low 6000's when I react and shift with my 4.10's.

big dave

I guess I'm somewhere around 6100 rpms going through the traps in 4th. I say I guess because it really was difficult to guage because of my valve float issues. I thought I was hitting the revlimiter but I wasn't even close to that.
Man I would love to be there but I'm out of the country til next week. I'm looking forward to trying out the new valvesprings next weekend. Good luck to you though. Post up your times or send me a PM after you get those new bests

LS1crazy01

iTrader: (14)

What size tire is it? Reason Im wondering is because im gonna be getting a n9inch soon and want a 4.10 and im turning the same RPM as you. Thanks in advance.

big dave

my tires are 25.6"

LS1crazy01

iTrader: (14)

Sweet thanks, I now know my 26" will be ok.

big dave

You should be fine on the motor...however, if you spray??

zfinke01

I have always shifted at 5500 and have run a best of 12.78@108.99 with only et streets and a adj tqarm. No reason to rev any higher it don't make any power up there.

big dave

Have you experimented with your shiftpoints and found 5500 to be the best?

zfinke01

Yes I have tried different RPM's and have found that 5500 work's the best. I was surprised to see how much my car would fall off by just raising the RPM's by a couple hundered. Every car is just a little different so every car will like a different RPM.

underated98Z

iTrader: (3)

Yea my cars best is when I shift at 5700rpm and I was shifting at 6200rpm for the longest. Im like the other guy why would you shift that high if it does not make the power after 5500-5600rpm. I don't speed shift either that is why I shift at 5700rpm so the rpm want drop to much during the next shift. Hopefully when I get to be a full bolton car I can get those times you got thoa.

LS1crazy01

iTrader: (14)

Dave I think it is true that you ran that time because if the track is preped very well you can dead hook a street tire. Back in 06 I ran my factory street tire and they prepped it very well because they had some big hp drag cars there all week long. I pulled up from the staging lane and tried doing a little dry hop since I was on just a street tire and they dead hooked! My first reaction was to check the TCS and it was off. So I reved it up to 5k and dropped the clutch and got just a few tire revelutions and pulled up to the line. I used to launch at 2800 rpm on the street tire but since I new it was real sticky that nite I took her up to 3500rpm! And then the light turned green and it dead hooked to my surprise. I think my 60ft was some where around the line of 2.0X when I usally ran 2.2X all day long.

big dave

Like you said, every car reacts differently which is why it really is necessary to experiment with different techniques to find what's best for your car.

I believe I tried shortshifting when I had the 3.42s but the car ran slower. I believe with the lower ratio rpms fall too far out of the powerband when shortshifting to be of benefit. I'm sorry I didn't try it sooner once I got the 4.10s. Your car runs really well for the minimal mods you have.

You're right, a properly prepped track can have you feeling like you're running drag radials.

180ls1

iTrader: (4)

here is a link with the stock dyno curve and look at the power dip when it is past 5500 i think you might be on to something. They also talk about how it does not make any more power past 5500 a few paragraphs into the article.
http://www.compcams.com/Community/Ar...ID=-1044516358

big dave

Good find. It really is a pretty informative article for those of us who are newbies to ls1s.