Scottie-GNZ

A 9-sec pass was just not to be, I guess. Car ran quicker in the 2nd 1/8-mile at SEZ but could not get it to hook to run a 9. I just was not willing to turn up the boost more and risk blowing something up for a 9-sec timeslip. I do not have a 9-sec timeslip but I know the car was quite capable. I just was not obsessed with it as others. This engine has served me well for 4.5 yrs and hundreds of passes (at least 100 10-sec passes). How's that for reliability and it does not even have forged pistons? As I read all those posts about reliable 500hp L28ET, I snicker and keep saying my Hail Marys, but also relish in my choice of engine for BIG HP. As for the Z, it no longer exists. Every part that could be removed (and some that was not meant to be removed ) is now in the possesion of other Z owners. Folks either did not understand or appreciate what was in that car or just did not have the funds. I still got what I was looking by parting it out and the biggest "gain" was knowing that I built it. I was not going to sell it to just any Zer and I hate dealing with tire-kickers and curiosity-seekers. Besides, once the F&R suspension was pulled it really was of no use to the average Zer. Let it R.I.P., err PIECES :D Mat, YOU ARE OBLIGATED to bringing your GNZ to the Reynolds BOP in November. Mike and I are planning to bring together the mad scientists again like at BG.

I guess sometimes copy and paste does not work: 1st: http://www.gsnationals.com/images/GS_Nats_2004_May_22_A_013.jpg 2nd: http://www.gsnationals.com/images/GS_Nats_2004_May_19_B_180.jpg Vid: http://www.gsnationals.com/videos/GS_Nats_2004_May_21_A_154.mpg

Take a look at the 1st pic. You will see a Buick 3.8 turbo with the intake turned backwards and a liquid I/C inside the car. You can also see it has a tube front-end. Guess what kind of car before looking at the 2nd pic. http://www.gsnationals.com/images/G...ay_22_A_013.jpg http://www.gsnationals.com/images/G...ay_19_B_180.jpg Here is a video of its debut pass. Right-click and save-as. http://www.gsnationals.com/videos/G...ay_21_A_154.mpg

Looks like the boxes actually survived! Stony, I am putting the drivetrain in a 2nd-gen RX7. Should start this weekend. BTW, Mark says hi. As you are probably aware, he is longer with Titan and is in the process of opening up his own fabrication business. Already has a 50,000 sq ft shop and waiting for his machinery. He will be doing my cage. He is also in the early stages of building an SR20-powered 240SX for the street-tire class to showcase the business and his goal is 1200+hp at the crank and hi-8s on DRs!!! I will put nothing pass him and his abilities.

HUH? Think you missed the point. Not trying to compare his ET or MPH or 60' to mine. What I was comparing was the MPH gained in the 2nd half. Main point was that despite me running much a quicker ET, much faster MPH, taller gearing and locking up my converter, I gained 28+ and he gained almost 26. If I did not lock my converter, the MPH gained wold be about the same. Rule of thumb says .1 change in the 60' affects the ET by .15. The difference between his timeslip and mine is more than just a quicker 60'. There is a matter of about 100hp, which just helps emphasize the point about how well his car ran in the 2nd half.

I tried and used several tires with varying success. Ran 275/50-15 BFG and Nitto DRs and had a couple of 1.55s. Then switched to 275/40-17 Nitto DRs and they were useless at the track. I then went to 26x9.6x16 QTPs and they served me well into the 1.40s. Last tire I ran were some humungous 27x11.5x15 QTPs and the numbers speak for themselves. Even though the 3.8 is a low-revver, I was leaving the line at 4600+ on a t-brake and they would beg for more Love QTPs! Not only do they hook, but they do not lose pressure even w/o tubes. Word of caution. If you decide to go to a bias-ply slick, seriously consider getting a set of bias-ply fronts also. With your speed it could get scary on top-end. I have several pairs of shorts with racing stripes in them from my experiences.

Rough rule of thumb to see if the car ran consistently in the 2nd half is: 1/8-mile ET * 1.57 = projected 1/4-mile ET 1/8-mile MPH * 1.26 = projected 1/4-mile MPH For comparison, you ran 122.8 and I ran 134.44 with 106.15 at the 1/8-mile for a gain of 28.29. Typically big HP turbo cars will have more MPH and also keep in mind that I ran a 3.07 final drive AND locked up my converter in 3rd. Locking my converter is good for about 2 MPH so no lockup brings me down close to what you ran. Difference is my 60'.

Congrats, Mike. If it was me I would hold of on the cam and work on the 60' with better tires. Your numbers are dead-on and with a gain 25.8mph in the 2nd half, that is stout!

Hans, no surprise on your results with retarding timing, BUT, you retarded the timing running the same boost. Let me repeat what I said: "The less timing you run (advance that is, not inital) the more boost you can run, the more power you make. ". Now, let me restate it. Retarding timing as you increase boost allows you to run more boost safely. You make more power from adding boost than from adding timing. Hans, in your case, when you retarded the timing, you could then have run more boost. B-25, your entire argument about timing loss/gain is based on a SPIKE!. 'Nuff said.

OUCH! My eyes!

I think throwing in # of cyls would add unnecessary complexity. E.g., if an SR20 and RB20 are making the same HP, it probably would not make any difference in the performance. Another example: a 300hp lightweight sr20 Z, a 350hp 240ZT and a 350hp LS1 240Z will probably be equal in the 1/4. Try to factor cylinders and it might get skewed. IMO, # of cyls really is not a factor in drag racing. Any other opionions?

False statement! Unlike an NA, retarding timing in a turbo motor as boost is increased makes a big difference in making more power and that is what the 6A BTM will help you do. No point in getting a fancy boost controller if you cannot turn up the boost because the timing is too high. The less timing you run (advance that is, not inital) the more boost you can run, the more power you make. I think you guys are skating on thin ice running 18+psi boost on pump gas with the stock ECU and some fuel system parts. If the 77 is 400lbs heavier, that makes all the difference in the world, plus, if the engine is pinging, it is losing power. You guys should buy an LM-1 and share it. That is the first thing I would do.

http://www.TurboBuicks.com/forums/showthread.php?threadid=22061&referrerid=225

No question is ridiculous if you truly do not know the answer.

What do you mean?

OK, since you have the RPM FUEL nailed down, then the focus will be on MANPRESS and IGN RETARD. I do them together because I do not like to increase boost without increasing fuel AND retarding timing. Not sure what your IGN table has, but for starters, I like to shoot for about 23* total at 15psi boost. I get that by building an IGN curve with an initial timing of 20* at 500 and 750 then ramping up the advance curve to 38* at about 3000, then 38* for the rest of the table. Then in IGN RETARD, start by pulling out 1* at about 3psi, then ramp that up to 15* at 15psi. So, at 15psi you would have 38* full advance minus 15* retard for the 23* total. For MANPRESS, there is no magic curve because there are too many variables that can affect fueling at WOT. Start off with the deault values in the map BUT start tuning for boost with the boost limited to say 6-7psi. Do not tune for boost in 1st or 2nd. Instead do it in 3rd and on an incline if possible (going up, of course ). Use the LM-1 to achieve your target A/F and if you have to adjust one way or the other, make the adjustment in MANPRESS. If you find you have to go a little richer at 7psi, then increase the numbers above 7psi also. Once you get 7psi nailed down then up the boost to 9psi, etc. Make small incremental changes like about by 3 in MANPRESS. Be patient, fine tuning a turbo car does not happen in one session. MOF, once you have 7psi nailed down, drive the car like that for a day or 2 before going to the next step. Your patience will be rewarded. Hope I did not muddy the waters but there is an expectation that you understand the basics. BTW, keep in mind that the numbers I give are for starters and you should fine tune and adjust accordingly.

OK, since you have the RPM FUEL nailed down, then the focus will be on MANPRESS and IGN RETARD. I do them together because I do not like to increase boost without increasing fuel AND retarding timing. Not sure what your IGN table has, but for starters, I like to shoot for about 23* total at 15psi boost. I get that by building an IGN curve with an initial timing of 20* at 500 and 750 then ramping up the advance curve to 38* at about 3000, then 38* for the rest of the table. Then in IGN RETARD, start by pulling out 1* at about 3psi, then ramp that up to 15* at 15psi. So, at 15psi you would have 38* full advance minus 15* retard for the 23* total. For MANPRESS, there is no magic curve because there are too many variables that can affect fueling at WOT. Start off with the deault values in the map BUT start tuning for boost with the boost limited to say 6-7psi. Do not tune for boost in 1st or 2nd. Instead do it in 3rd and on an incline if possible (going up, of course ). Use the LM-1 to achieve your target A/F and if you have to adjust one way or the other, make the adjustment in MANPRESS. If you find you have to go a little richer at 7psi, then increase the numbers above 7psi also. Once you get 7psi nailed down then up the boost to 9psi, etc. Make small incremental changes like about by 3 in MANPRESS. Be patient, fine tuning a turbo car does not happen in one session. MOF, once you have 7psi nailed down, drive the car like that for a day or 2 before going to the next step. Your patience will be rewarded. Hope I did not muddy the waters but there is an expectation that you understand the basics. BTW, keep in mind that the numbers I give are for starters and you should fine tune and adjust accordingly.

Do a search and you will find many postings on this including some very detailed instructions and even examples. The baseline number for RPM FUEL is derived by using the cylinder displacement and inj flow rate and this table.

This is something I have been using for some time to help my performance estimates and evaluations. Give it a whirl and hope you find it useful. Also hope I did not make it too complicated to use. Do not update the online copy, PLEASE! Download a copy for your future use and you do need Microsift Excel. http://www.turbobuicks.com/members/scottiegnz/estimates.xls Enjoy!

WELL DONE!!!

Terry, without a doubt, put that cam back in. Losing a little torque from a SBC in a light Z might even help you a little.

Congrats. Car has lots of potential. You had a good 60' on the 2nd pass but whatever went wrong started right after the 60' as the car was .5 slower between the 60' and the 330' compared to the 1st run. If the car was running right, the 2nd pass should have been in the 12.2 range. Car gained less than 18mph in the 2nd half and I would say you need to look into WOT tuning and I also think the 3.90 is part of the culprit. If that is just an open diff I would pick a 3.54 and swap that in. Corzette, congrats on your runs also. Hard for me to believe that a cam can gain 50hp over another performance cam but then I have not messed with NAs for a long time.

You will be amazed how much boost you can run safely with a good I/C and race gas. Advice for the 1st-timers: - Reaction time has no effect on the 1/4 time. MOF, for your first pass, ignore the green light and go when you feel comfortable - Completely resist the temptation to "race" the car in the other lane and just focus on what you are doing - No matter how badly you want to make it down the track, if you feel or hear anything strange, GET OUT OF THE GAS! - The butterflies will feel like bald eagles in your stomach so when you finish your 1st pass, go ahead and wail out a big "OH YEAH!". Don't be embarrased, we all do it - You are not going to maximize the car's full potential on your first trip to the track, so anything short of going home on the hook is a success. Most of all, just have fun.

12.3 @ 115 with 18psi.

I see lots of good HP parts and I also see a 3.90 diff but no mention of tires. I predict you will be fogging mosquitos until you figure out how to get the car moving under power with street tires :D Good luck and just have fun. 510six, that is simply not fair