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Getting away from a stop has improved so much in my car since installing the MSD 8762 boost retard box and advancing the base timing by turning the distributor.
These cars need alot more ignition advance than the stock emission control oriented setup gives to run as good as possible before boost starts. My car is so much more fun to drive now since doing that and I havn't got it tuned optimumly yet. There's alot more information about all that in Keiths thread on timing that is on page 2 now until someone posts in it again. http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/500986-ultimate-930-distributor-advance-retard-timing-turbo-lag-msd-mod-thread.html |
Okay, 2 pictures which may interest you... Post up yours - let's see whatcha got! ;)
http://farm3.static.flickr.com/2163/...cc7d0b7d_o.gif http://farm4.static.flickr.com/3014/...2f8f5ca0_o.gif |
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I think I'm going to have to dig into my instruction manual ;) |
Well if you go to GTech's web site, you can download it - I think this is the link.
http://www.gtechprosupport.com/support/pass/2.0.0/GtechPass20install.exe You might need an (old-fashioned) serial wire to link to your PC. But, on the forum, there's a guy there with a 4WD 996tt who also dared not 'launch the car' - comparing drags - up until about 30mph, I was ahead... Then ;) |
OK... my GTech actually came with a serial connector... I should be able to figure this out.
Thanks |
Well, you may have to get your shovel out and dig up one of those Personal Computers with an archaic 'serial port' (somewhere about the Jurassic period ;))
But, as I say, you can go to the Website's GTech Forum and actually download 'Drag runs' from all sorts of cars from all over the World. (I was really surprised to find that my old wreck was waaaaaaaaaaaaay quicker than about 90% of the cars that were on there :)) |
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The problem with 8/41 is that it is ONLY for the holeshot IMO. The rest of the time first gear is uselessly short. 4th gear is also too short although breath-taking in acceleration. Custom gearing is better IMO. I need a longer 1st and 4th. However if hard acceleration is your only goal, the 8/41 is PERFECT and I do not think you could change it for the better. Even a computer simlulation game which lets me customize gears on a 930 shows the 8/41 set-up is the fastest possible combo for acceleration. |
Ms. Jewelry (16)
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Tom, that second run gives you a 60-130mph of 17 seconds!! That's really slow! You can hit about 132-134 mph in 3rd with stock wheels and a stock 4 speed, you need to hit the rev limitter but you'll get there.
I've not heard of this GTech device, most use the Drifbox or AX22, but i don't doubt this device does the same thing. I've never bothered doing a 0-60 run, just don't think it's sympathetic on the car, it's a much better performace measurement doing a rolling start, wheel spin and clutch control don't really come to play then. Looking at when you are hard on the throttle, with no gear change involed, 50 to 80mph comes up in 3.21 seconds which is respectable. Would be really good if you could do a slow roll in 2nd from about 30mph, then plant your foot until up near the red line, change to 3rd and leave your foot there until you hit the limitter, that graph would be far more telling |
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When on DE days I spend most of the time in 2nd and 3rd and try to take some turns in 3rd and it lugs too much but 2nd would be too low. As an FYI, I talked to someone at Motor Meister the other day about a R&P set and they quoted my $2800. They told me that they don't sell many anymore but sell 3.6 kits for about the same price instead. |
If you do a search in the "911 Engine Rebuilding" forum for "Motor Meister", I bet you will NOT want to send any of your money their way . . .
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And yeah, a shorter third is amazing. I recommend 3rd to about 115-120 mph like mine. |
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Obviously altitude has an effect on acceleration and power. The GT is accurate but can be fooled by up and down vertical motions from the vehicle, translating that motion into more distance travelled to reach speed i.e. slightly slower times. I know my 930 reaches for the sky between shifts when I go thru the gears quickly. Also the 1989 is over 100 lbs heavier than an '88 which is heavier than a '79, ect... So those are just three variables to start with anyway. If you have 17"inch tires you give up a little in the holeshot with taller effective gearing. So you can imagine yourself giving away maybe a second if all the above play a role. And yet 6 seconds in real world terms is very fast, and nobody normally duplicates magazine testing times in the real world anyway. Most magazine tests have the 930s in the low five second range and just cracking the 13s at maybe 112 mph so you are getting consistent times which are solid. |
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My car was doing 60ft in about 2.2 seconds, so 3s does suggest something being wrong somewhere :( |
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I left both vacuum lines on the '87 USA distributor and turned it clockwise advancing it as far as the adjustment slot allows without pulling the distributor out and reindexing it one more gear tooth.
I'm scared to remove the vacuum retard line so far because I don't know where the timing would go under boost then. Just too risky. I need to get some kind of degree wheel or tape that can be attached to the crank pulley and has the degree marks on the edge so it will be visable when pointing a timing light down at it before I experiment with timing safely. At the moment I have the MSD 8762 set to retard timing 2 degrees for each psi of boost starting at 5psi but I will probably change that a little with more experimenting. I run maximum boost 1 - 1.1 bar or around 15 psi with street gas, usually chevron high test. The motor has stock 7:1 pistons and cylinders, 964 cams, Garretson long neck half bay intercooler, and B&B headers. It has fuel enrichment with a modified IA fuel head and Brian Leask adjustable WUR to control it. |
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I can tell you that my 3rd redlines at 115 or so and that is as short as you would ever want to go. I think 120 mph might be perfect for full acceleration. Bruce anderson's 911 performance handbook has all the possible gear ratios and mph in the back. Looking at the book a 26/26 gear at 6800 rpms gives 120 mph with a 9/38 ring and pinion. That would be devestating acceleration and just a touch taller than what I have. A 27/26 would put you at 126 mph and stock I think is about 134 mph at 6800 rpms. The 126 mph gear seems like a very nice compromise because your gear would not seem too short either. You would want to double check those gears numbers yourself... |
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