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View Full Version : Looking for 11.5-12.0 quarter mile time what should I do next?


kna4977
09-12-2007, 04:18 PM
Been out of the loop for a while, but now that I am confident in my GN again, it's time to carry on with mods.

What I have is a basically stock 87 GN except for Walbro 340, K&N 9" cone filter, Billet Adj Fuel Pressure Regulator, TurboTweak Street Chip, AC Delco R43-TS plugs, 160 T-Stat, Powerlogger Scan Tool. Everything else is completely stock including plug wires, turbo, intercooler etc. Exhaust is new from the cat back. This setup produced 210 RWHP and 310 RWTQ at 14-15 lbs boost on 93 octane pump gas.

Looking for mid 11s to low 12s. How much horsepower do I need to do this, and what should my next modification be? Can I achieve this safely and consistently without breaking the bank?

ed39
09-12-2007, 07:28 PM
Wat year tr is it??

Keller
09-12-2007, 07:53 PM
Wat year tr is it??
You can check his profile...

Have you checked the recipes for suggested pathways to getting the desired result? I do realize some of these may seem a wee bit dated, but they have always worked and have been effective. Some small concessions for new technology (i.e. Mototron 60 Lb. Hr. injectors, etc.) can easily be made, but the process always follows the same pathway.

That being said, some of these recipes are past their "born on" dates. A little alcohol...some GT and/or ball bearing turbos...some new generation intercoolers...affordable wideband O2's... Who will author the recipes for this generations TR pilots?

kna4977
09-12-2007, 08:18 PM
1987

Most of the recipes dip down to the 9s and 10s which is a little further than I want to go for this car. Of utmost importance is affordability, safety, reliability, performance, mostly stock, consistant 11.8s or so. I would like to stay away from the high dollar items such as turbos, intercoolers, and downpipes if at all possible. Maybe with your help we can come up with a low budget recipe that provides consistent results while keeping the turbo regal as stock, collectible, enjoyable, and up to date technology wise as possible. In other words, "well-rounded".

kenmosher
09-12-2007, 09:37 PM
Basically, follow the Recipe down to the low 12s (before any real hard parts, like turbos).

Stock turbo, some alky, good fuel pump, basic maintenance (plug wires, good coil pack, etc.), some traction (slicks), and good exhaust and 21 psi and it should crank off 12.20s @ 109 or so.

kna4977
09-12-2007, 09:44 PM
Basically, follow the Recipe down to the low 12s (before any real hard parts, like turbos).

Stock turbo, some alky, good fuel pump, basic maintenance (plug wires, good coil pack, etc.), some traction (slicks), and good exhaust and 21 psi and it should crank off 12.20s @ 109 or so.

What kind of horsepower would I be putting out with these numbers?

Probably run racing fuel instead of alky, but may set up alky anyway.

Suggestions on plug wires?

Stock coil pack okay?

What would be a preferable exhaust system?

IL KIM
09-12-2007, 11:22 PM
Been out of the loop for a while, but now that I am confident in my GN again, it's time to carry on with mods.


Thought you had a knock issue and were looking for someone to rebuild your engine? How'd you gain your confidence back? - maybe some on the forum can learn from your experience.

Keller
09-13-2007, 12:31 AM
I agree with Ken here. I did it...stock exhaust (less cat), downpipe and all!

No idea who's exhaust fits and works well now. The good ole' Hooker setup works great, but is a mild steel system. Cotton's may have stainless systems. (Check in - Exhaust)

Stock coil works for 8's. Old 230+ MPH Indy Buick V6's too. Not good enough for you? :what: (Check in Engine - Electrical/Ignition)

No need for alcohol if you go straight race fuel. I've not made the switch yet.

kna4977
09-13-2007, 07:52 AM
Thought you had a knock issue and were looking for someone to rebuild your engine? How'd you gain your confidence back? - maybe some on the forum can learn from your experience.

I did or so I thought. Took it to a GN specialist here in TX who took apart the bottom end and basically found nothing except for the little bit of wear on the back bearing that I had already discovered. He replaced all the bearings anyway and said the internals looked great and that the car looked to be low mileage and never ran hard. The only things we could think of is that after the dyno run we got some detonation on the back 2 cylinders causing the sound and wear on that bearing. The other issue, and probably the most likely cause is a balance issue with the flywheel. The flywheel at some point has been switched out and the bolts have been hack-sawed off. I don't know why anyone would do this, but anyway. Good news is they are close enough to the center of the flywheel that they really shouldn't make all that much difference as far as centrifugal force. Torque converter is also non-stock. It's blue and has a D-5 front but the back of it is different. I think he said smoother and cleaner. So my thinking at this point is that when the transmission was taken out for the front seal replacement something wasn't put back in lined up exactly as it would want to be causing false knock and/or balance issues. Don't know if my experience would help anyone or not, but there it is. On with the mods!

kna4977
09-13-2007, 08:00 AM
I agree with Ken here. I did it...stock exhaust (less cat), downpipe and all!

No idea who's exhaust fits and works well now. The good ole' Hooker setup works great, but is a mild steel system. Cotton's may have stainless systems. (Check in - Exhaust)

Stock coil works for 8's. Old 230+ MPH Indy Buick V6's too. Not good enough for you? :what: (Check in Engine - Electrical/Ignition)

No need for alcohol if you go straight race fuel. I've not made the switch yet.

What about a gutted cat with exhaust leaks a plenty??

230+ MPH should work just fine for me. So stock coil it is!

Race fuel it is

Also, I think I saw some sort of equation on some site that would allow me to calculate how much horsepower I would need to carry such and such weight over a certain distance at such and such speed and/or time. Anyone have an idea where I could find such a calculation?

ed39
09-13-2007, 03:56 PM
my set up for now on my car is high 12s. blue top inj,hot wire kit, regulator, intake, exhaust with 3inch downpipe, tt chip, lt1 3inch maf,255 50 16 bfgs street tires, shift kit, 2400 stal. think next ill go alky and stickys.... if your a street car alky is a great way to go 21-23 pounds of boost not to shabby. def go the gutted cat with good flowing muffs works great

IL KIM
09-13-2007, 09:22 PM
Thanks for the update! On with the Mods!

TNTBuick
09-13-2007, 10:00 PM
richmondgear.com

TNTBuick
09-13-2007, 10:16 PM
Sorry, I should have explained. richmondgear.com has a drag performance calculator and a couple others that calculate rpm and gear ratios. I'm sure there are others, I just happened to remember this one.

kna4977
09-13-2007, 10:41 PM
Sorry, I should have explained. richmondgear.com has a drag performance calculator and a couple others that calculate rpm and gear ratios. I'm sure there are others, I just happened to remember this one.

Thanks, that helps. Looks like I need about 350 to 375 HP to do this. I assume that is at the rear wheels

TNTBuick
09-13-2007, 11:39 PM
I was thinking at the flywheel, but can't remember right now. I'll try and let you know tomorrow if someone hasn't already responded.

Keller
09-14-2007, 02:05 PM
For reference, my car dynoed around 375 RWHP 450-475 RWTQ and has gone 11.76. YMMV.

kna4977
09-14-2007, 03:33 PM
Thanks Scott. Those equations must be a fairly good estimate. Would it realistic to get those numbers (~425-475 HP at the crank or ~340-380 RWHP) safely without the major bolt-ons? Just not sure how I would be able to increase RWHP by 165 over baseline without doing something major. Maybe 12.5-13.0 quarter mile times would be a more logical goal??

Keller
09-14-2007, 04:04 PM
Would it realistic to get those numbers (~425-475 HP at the crank or ~340-380 RWHP) safely without the major bolt-ons?
Not sure what you consider a "major bolt on"?

I've never opened my motor or removed my heads. Do have a TA49 and injectors, downpipe, reworked trans and converter. Some additional stall and trans improvements would be advised. I have a stretch IC now, but did not for the 11.76; just a recored stock sized unit. Also an aftermarket fuel pump and "hot wire" kit. I have shocks, rear upper and lower arms as well, but I think those are not 100% necessary. I have DOT rears, and I think those are 100% required for a good ET with that sort of HP in these cars. As is a driveshaft safety loop.

Any of these pieces "major bolt ons" in your opinion?

kna4977
09-14-2007, 04:36 PM
Not sure what you consider a "major bolt on"?

I've never opened my motor or removed my heads. Do have a TA49 and injectors, downpipe, reworked trans and converter. Some additional stall and trans improvements would be advised. I have a stretch IC now, but did not for the 11.76; just a recored stock sized unit. Also an aftermarket fuel pump and "hot wire" kit. I have shocks, rear upper and lower arms as well, but I think those are not 100% necessary. I have DOT rears, and I think those are 100% required for a good ET with that sort of HP in these cars. As is a driveshaft safety loop.

Any of these pieces "major bolt ons" in your opinion?

Anything that costs $500 or more to me is a "major bolt on". Not necessarily major to install, but major in out of pocket expense. Haven't really researched prices all that much, but what I have seen is ~$300 for injectors, at least $500 for a turbo if not $800 to $1000. The downpipes I have seen are at least $400. If anyone knows of a place to find these things cheaper, or if I'm off the mark, let me know. Got the fuel pump and hot wire and will check into tires, driveshaft safety loop etc. Not sure what I would have to do with my transmission as it has had some work already and shifts very firm and well.

Keller
09-14-2007, 06:42 PM
"Speed costs money, kid. How fast do you want to go?"

Attributed to many, but most likely first uttered by Banjo Matthews in the early days of NASCAR. No truer words ever spoken in the world of automotive performance.

Give http://www.consumeraffairs.com/auto_racing/speed_costs_money.html a read. A good idea how a "small project" (this one road racing) gets bigger in a hurry.

Good, fast, cheap: pick two of the three as your goals. Can't have all three. Period. Otherwise, you get to do it all over again.

kna4977
09-14-2007, 09:02 PM
"Speed costs money, kid. How fast do you want to go?"

Attributed to many, but most likely first uttered by Banjo Matthews in the early days of NASCAR. No truer words ever spoken in the world of automotive performance.

Give http://www.consumeraffairs.com/auto_racing/speed_costs_money.html a read. A good idea how a "small project" (this one road racing) gets bigger in a hurry.

Good, fast, cheap: pick two of the three as your goals. Can't have all three. Period. Otherwise, you get to do it all over again.

Definately words to live by. I would probably pick Good and Fast. I want to go fast enough to beat a new stock Z06 in the 1/4 mile......12.5 seconds or quicker. Seriously doubt I could match the 0-60 of 3.7 seconds though, and definately wouldn't autocross against it.

Keller
09-14-2007, 11:57 PM
Seriously doubt I could match the 0-60 of 3.7 seconds though
You might be surprised. I'll try to take the G-tech out next time. I know I've seen some low 4's in the past on some 12-flat runs.

kna4977
09-15-2007, 06:52 AM
You might be surprised. I'll try to take the G-tech out next time. I know I've seen some low 4's in the past on some 12-flat runs.

Cool! Nothing like $80K performance out of a $15K car......try to keep it level so you get an accurate reading.

Survivor87
09-20-2007, 01:16 PM
Don't worry about the 0-60. Just be first to the finish line. From what I'm hearing, though, you better be solid in the 11's before you pick on one.

kingots2004
10-11-2007, 01:14 PM
hows the modds coming have you got the performance you were looking for?

kna4977
10-11-2007, 06:59 PM
Mods are coming along nicely, getting close to what I am looking for, for now anyway. Thanks for asking.

PaCemkr86
10-12-2007, 10:05 AM
lets see some pics

Electrajim
10-12-2007, 03:14 PM
Some affordable "mini-bolt on's" can help a little.
http://www.throttlebodys.com/Buick%20GN.htm
Try port matching the throttle body, upper intake plenum. Porting turbo exhaust elbow too. Can't hurt, and can only help in an overall combination.
This is all stock appearing stuff too! :tup:
You can keep that stock downpipe on for a while.

Major bolt on may be ported heads, and intake from Champion, turbo, but thats a lot of work, and it's gonna cost ya.

ElectraJim

Keller
10-12-2007, 03:47 PM
As stated above, "Speed costs money, kid. How fast do you want to go?"