Grand National questions

[Nightrage]

Last night i was at my friends house. He has an 87 Grand National. He claims that he's running 19lbs of boost. His car is stock aside from the headers he put on last year. Don't GN's only run around 10lbs of boost stock? It's just a Grand National, it's not a GNX. He doesn't have an intercooler either. He took me for a ride in it and he floored it. I wasn't pushed back in the seat or anything. It was still a real nice car though.

[aschroeger]

I thought all '87 GN's had the intercooler.

[4THGEN Z]

I thought all '87 GN's had the intercooler.

I thought the same thing....

[jspeed97]

Interesting that his 87 GN doesn't have an Intercooler. All 1986 and 87 GN's and T-types had an Intercooler. This was the big difference from all the other years. The HP was under rated from the factory because of the unspoken rule that you do not have a faster car in the GM lineup than the Corvette. 1986 cars were rated at 235hp at 3300 RPMs, and 87s had 245hp. Actually, they were pushing the 275hp range, and the cars could run a low 14 sec quarter. Not bad for a car that weighs around 3800lbs. If you turn the boost up though, they could do high 13-sec runs on slicks. As far as factory boost, 86's usually ran around the 12psi area and 87s, closer to 15psi. I guarantee he is not running 19psi, if he was, you would have been screaming like a child when he floored the accelerator. My guess is he doesn't have a clue what he is talking about, and the car is probably in need of a tune up. If his car is a 87, I have a hard time believing that it doesn't have a intercooler, unless someone took it off and turned down the boost to around 6psi, or its a 85 GN. Right now, I am in the process of upgrading an 86 T-type. When we are done, it will be boosting around 18psi. I'm hoping for 13.0-second car. We ended up getting a Precision GT3255E Turbo, roughly comparable to a TE-44. If we wanted, we could go up to 20 PSI, but I didn't have the new chip programmed for that. We wanted a reliable daily driver, that we could have some fun with. Nothing like burning Ricers with a Granny Grocery getter, muhahahahahah.....

[aschroeger]

Grand National Information Page

http://www.gnttype.org/misc/info.html

[Nightrage]

Here's the story. My dad bought his Viper and suddenly, everyone was interested in cars (that we associate with). My dad's best friend is the father of the kid with the GN so they're more like family as i pretty much grew up with them. My dad's friend has a Monte Carlo SS. He had a seething hatred for it. Suddenly, my dad got his car and the guy ordered a custom 350 that he plans on swapping in. He got a 2" cowl hood and cleaned the car up real nice. His son wanted something that could beat my dad's car. He and his dad checked out cars and eventually ordered his Grand National off of Ebay for $7,000. They had to do some work to it but they eventually got it running (my dads friend was a mechanic for something like 20 years). When he got the car, he tried to get on it and blew something. It cost him about $1,500 to get the car running well. Last night, i went to his house and they were working on the car. I don't even know what's wrong with it but i know that in addition to whatever they were working on under the hood, the tranny is on its way out. He's ALWAYS complaining about how he doesn't have an intercooler. He also said that intercoolers only add torque. Other people have told me that they add horsepower in addition to torque. The first thing i asked was "how many lbs of boost do you run in you're car?". He replied "19". I laughed and said, yeah right, you wish. He still claimed he does. As sad as it is, i don't think they know the difference between the Grand National and the GNX One more question. I've been told that 1lb of boost is equal to about 10 horsepower. Is this true?

[markd79ta]

Interesting that his 87 GN doesn't have an Intercooler. All 1986 and 87 GN's and T-types had an Intercooler. This was the big difference from all the other years. The HP was under rated from the factory because of the unspoken rule that you do not have a faster car in the GM lineup than the Corvette. 1986 cars were rated at 235hp at 3300 RPMs, and 87s had 245hp. Actually, they were pushing the 275hp range, and the cars could run a low 14 sec quarter. Not bad for a car that weighs around 3800lbs. If you turn the boost up though, they could do high 13-sec runs on slicks. As far as factory boost, 86's usually ran around the 12psi area and 87s, closer to 15psi. I guarantee he is not running 19psi, if he was, you would have been screaming like a child when he floored the accelerator. My guess is he doesn't have a clue what he is talking about, and the car is probably in need of a tune up. If his car is a 87, I have a hard time believing that it doesn't have a intercooler, unless someone took it off and turned down the boost to around 6psi, or its a 85 GN. Right now, I am in the process of upgrading an 86 T-type. When we are done, it will be boosting around 18psi. I'm hoping for 13.0-second car. We ended up getting a Precision GT3255E Turbo, roughly comparable to a TE-44. If we wanted, we could go up to 20 PSI, but I didn't have the new chip programmed for that. We wanted a reliable daily driver, that we could have some fun with. Nothing like burning Ricers with a Granny Grocery getter, muhahahahahah.....

The '87 GNX was clocked at 13.70@102 stock

source: http://www.musclecarclub.com/musclec...s-50fast.shtml

You can't take all of these times as gospel, but they give you a pretty good idea of how the car was tested stock. The GNX was capable of much better times with some tuning and tweaking of the turbo, but that is not allowed for the purposes of these tests.

[Joe 1320]

Here's the deal...... intercoolers were stock starting in 86. So something right off isn't correct. Next, these cars don't like over 17 psi in 3rd or 4th without a serious boost in octane, more effecient intercooler and/or richer mixture. 19 psi is merely going to heat the air, it will knock and timing and boost will be pulled out by the computer. If he is running a non intercooled car at 19 psi, he'll need high octane fuel. Not only that, the fuel pump is marginal at stock boost levels, so doubtful again he would be at 19 psi without a better fuel pump.

If he thinks he' running 19 psi, my bet is that his gauge is wrong. It is common for the stock boost gauge to be way off.

[jspeed97]

I'm almost a 100% sure that the stock digital boost guage only went up to 15 psi, and yes, they are very unreliable like Joe said. Infact, we ordered a after market boost guage so that we can see what is going on with the Turbo. Joe is completely right about the Intercooler and the 19psi. You need to send these guys to the http://www.gnttype.org/misc/info.html web site. That web site has helped me tremendously in studing up for my resto. on the 86' T-type. Just to give you an idea of what these guys will prob. need, check the parts list we ordered to get are Buick screaming again.

Note: Our car only has 77K miles, and is in perfect condition besides the dead stock turbo.

Precision GT3255e Turbo
Bosch 42.5 injectors
Magnecore 10mm Plug wires
New Heavier duty Turbo Hoses and clamps
Racetronix Walbro 340 Fuel Pump
Lunar Boost Guage 30psi
AC spark plugs, forgot the exact part #, but can be found on the web site under spring cleaning.
New Valve Seals
New Chip, programmed to our exact setup and boost setting.

If you want to see a pic of the Buick engine and the intercooler, go this site:
http://www.gnttype.org/techarea/techpage.html

[PingMe]

With a chip this car will easily do 19lbs of boost. My 89 TTA did it on a regular basis. You really don't get into trouble until you exceed this. At 20+ lbs you must run racing fuel and do other mods, like turning up the fuel pressure, or you risk eating holes in the pistons or more commonly, blowing head gaskets. The 89 TTA will throw you back in the seat and keep you there.

[Joe 1320]

With a chip this car will easily do 19lbs of boost. My 89 TTA did it on a regular basis. You really don't get into trouble until you exceed this.

Different car. Same shortblock, different heads, different fueling and program. TTAs will take a bit more boost before behaving badly. BTW, you don't need a chip, just an adjustable wastegate or a bleeder valve.

Just to give you guys a little background, mine has the following:

109 block turbo block .030 over
RJC block girdle
Steel mains
O-ringed block deck
TRWs
ARP studs and bolts
ATR billet roller cam
Ported Iron 8445s
Cometic Headgaskets
Port matched and ported intake
Double core ice boxed intercooler (race)
(7) yes, Seven 50# injectors (ATR 7th)
93 and 110 race chips
Walbro 340
Casper's hot wire kit
Poston's ceramic headers and crossover
Kirban Jet hot coated 3" downpipe.
Undisclosed turbo gotta keep something secret.
Kenne Belle Ram air
Kenne Belle 3" Single shot with twin stainless ultraflows
Scanmaster

and thousands of buxs worth of small items too numerous to mention. Everything from rollerized cam button, undercut valves, suspension stuff to billet parts in the trans. It's a GNX clone hardtop car that is incredibly fun to drive.

[Nightrage]

i stopped by the kids house again tonight. Turns out it's an 85. I was way off. He still calims he runs 19lbs of boost though.

[Joe 1320]

Things are making more sense. He can run 19 psi though. However, there will be no benefit. Physics states that air, once compressed, becomes heated. Above 15 psi, inlet temps rise to the point that the air becomes hot and much less dense. The sensors read this, the computer backs out timing to avoid detonation. I've seen cars lower the boost and run quicker. Sounds like the guy needs to do his homework.

[DJCamaro]

I've never been impressed with GN's.... They never seem to run right, and are wayyyyy to finicky. My friend has an 87 GN and all I heard about was how it was going to destroy my old Mustang.... Needless to say we went to the track and his car was embarassed by my well-tuned, but basically all bolt-on 91 GT. I was running 13.70's and he was in the 14.50's. He brought the car to Turbo People in Upstate NY. They said his Tanny was toast and he had the wrong chip. Bring them back to the track. Mustang 13.70's again... all day long. GN $3,000.00 later.... 14.0 even.... Not impressed. He's talking about racing my SS now. He couldn't beat the Stang, why try the SS???

[gimp19]

I've never been impressed with GN's.... They never seem to run right, and are wayyyyy to finicky. My friend has an 87 GN and all I heard about was how it was going to destroy my old Mustang.... Needless to say we went to the track and his car was embarassed by my well-tuned, but basically all bolt-on 91 GT. I was running 13.70's and he was in the 14.50's. He brought the car to Turbo People in Upstate NY. They said his Tanny was toast and he had the wrong chip. Bring them back to the track. Mustang 13.70's again... all day long. GN $3,000.00 later.... 14.0 even.... Not impressed. He's talking about racing my SS now. He couldn't beat the Stang, why try the SS???

His GN must not have been in very good shape, I've never owned one but 14's shouldnt be a problem stock.