HEADS UP DISPLAY. A DIGITAL PROJECTED DISPLAY ON INSIDE OF WINDSHIELD CONTAINING VEHICLE INFO SUCH AS SPEED, ENGINE TEMP, RPM, ETC. FOR DRIVER INFOR...
Subject: Re: Transmission question by dan0617 on 2008/12/31 22:08:28
Quote:
BeachBum wrote:
Yes, I think mid to low 11's are very possible with that 383 set-up with the right converter. However, I am not a big fan of your chosen hyd flat tappet technology choice.... that'll probably hurt you a tenth or two as compared to a like hyd roller. I did a test years ago on the change... I improved 2 tenths with the move to hyd roller with less duration, but more lift, which at that time was probably a solid 20-30 hp with my 350. But, even so, deep 11's will be easy.
The only reason I'm running that flat tappet cam is because it is the same duration I wanted for a 383, fits my bottom end and intake's powerband pretty well, and most importantly, it came with the shortblock when I bought it. It costs alot to go over to a retro roller setup, and my bottom end won't allow any more rpms than the flat tappet will give me so the only benefit will be friction, ramp rates, and lift. And my lift isn't bad on the flat tappet. I agree I'm giving up 20 or so hp. Thing is, I know this 383 is only a 3 year engine for me, I want to either rebuild the stock roller block to a 383 that uses lightweight components and spins to 7000, or put in a 434. Giving the limitations of my current 383, my future plans, and the fact that this cam was already installed and came free with the shortblock, I decided to keep it.
Quote:
Keeping your rpm's up is a good thing if accelerating.... I won't say how much it will effect your slap-back rpm, every set-up is a bit different, but it won't be too drastic is my guess.
On your gearing, its not as bad as you think..... in reality, with your most important gear for happy timeslips, which is 1st gear, a 3.07 rear gear with a 700R4 is exactly equalivent as a th350 with a 3.73 gear if you do the math..... (3.06 x 3.07 = 9.39 and 2.52 x 3.73 = 9.39) Whats bad is a 2.59.... I don't know what GM was thinking on that one.
As a note, with a 383 Superram motor, I did a very detailed before & after test years ago from 3.07 to 3.45.... I had zero et improvement on that investment, just wasted my money. But, it was a little funner to drive on the street, 2nd gear was much more usable around town. However, your HSR curve would probably see a small et improvement with more gear, but not sure. What we concluded on that, is that if you already have a good converter, gearing improvements on torque laden street motors, unless very poor ratio's to begin with(ie 2.59), do not really help you.....this was a well publicized test on the CF years ago...... but fast forward to 2008, and all of the tests the old timers did years ago seems to be forgotten or lost, cuz many do not believe this and continue to upgrade their gears and report back how fast they are now, albeit, they don't race, and instead base their conclusion on how it feels on the street. After I had done my 3.45 gears, it did feel faster on the street.... but the timeslip straightened me up and told otherwise.
Back on your converter, I do not recommend you go out and loosen up your converter to 3600 rpm just based upon my opinion..... ask around, get some feedback as to the driveability of a looser converter. I think in late model forums, the general consensus is that as you get over 3000 rpm, the drivebility goes south pretty fast.... I won't argue with that, but will only say, each driver has their own idea of daily driver material. Whats livable for me, may not be for you..... so do your homework and make sure you'll still have an enjoyable driving experience before you do it..... but do rest assured, you'll go faster if you do loosen it up. btw, Azzoto's stall is approxmiately 5500 rpm..... not sure if he gave you a ride in it or not..... thats an A-typical dragstrip race converter. But, I know he does drive it on the street and reports back its fine on the street..... although I have a feeling many wouldn't share his thoughts on that.
Well, thats my opinion anyway....
Thanks for all this info. I am not sure yet, but I truly appreciate your opinions and advice. I'd bet money that my 2800 stall would be the same on the street as a vig or other top of the line 3200. It is loose, IMO. I haven't decided anything for sure yet but if Pete builds me a trans or if I find a used trans I think I'll stay with my converter for now, and hold off on upping the stall speed till I upgrade to a solid rear. I just don't want to have myself spent down too far then blow the rear. Could happen anyway, but much more likely to happen the higher I raise the stall speed.
You mentioned dialing my setup in on motor before spraying. Definitely. I have a place near home that I can run it out on the street to get the tune and afr dialed in. The wideband 02 gauge is the cat's ass. Once it is dialed in, I'll start with a 100 shot and not spray till after it shifts to 2nd gear. I'll use an extra large fuel jet, then trim it back till I get the afr where I want it. Then I'll do the same with a 150 shot, then a 175, then finally a 200 shot. I have a timing retard box so my tune will be set up for N/A and I'll pull 2 degrees of timing per 50 shot. I always stay conservative on timing and afr and if I want more power I'll run a bigger shot of nitrous instead of running on the ragged edge. I might try spraying it part way through 1st gear at the track but not on the street. I won't launch with the spray until I have the solid rear. That is my plan anyway, time will tell!
