Question for Scottie

[Guest Anonymous]

I've seen a few of your replies recommending the GN setup for drag racing and the 350 V8 for autocrossing and GT racing. Was wondering if you could please elaborate on this?

[Scottie-GNZ]

quote

I've seen a few of your replies recommending the GN setup for drag racing and the 350 V8 for autocrossing and GT racing.

 

Ashe,

 

not sure I went so far as to say that. The GN engine is only available with the TH200R4 automatic. You can convert it to a manual as long you are aware of the gearing. The Buick cars do not make good autocrossers or road racers as they came setup from the factory. Please reread that statement to make sure it is understood, because when Buick made an attempt at improving the suspension in the GNX, it pulled .92G on a skidpad with mid-80s tire technology. Folks who have swapped the GN engine into other cars did it primarily because of the HP/torque potential for drag racing and stuck with the automatic because that was what worked best.

 

[On soapbox] I have long since gotten over the "this is a sports car and it must have a manual gearbox thinking". [Off soapbox]. No reason why the GN engine/automatic cannot work in autoX or road racing, you just need to do more throttle modulation, especially autoXing, to control the explosive rush of power.

 

I just noticed you are in Clermont. Drop me an email tonight and lets get together. MOF, if it stopped raining I plan to test the car tomorrow night.

 

[ July 24, 2001: Message edited by: Scottie-GNZ ]

[fl327]

dontthink that swap was cut out too good for autoX ,kicks ass at the strip though,

[BLKMGK]

The Buicks I've driven have had some noticable lag to them followed by some really NICE torque. I would imagine that at an AutoX this would be a real PITA to drive around. A stick wouldn't make it any better either and might even make it worse. I know in my RX7 I've got to be VERY careful of where I'm at when the boost hits, if I'm halfway through a turn and it hits hard I'm SOL - it can be scary. I'd think the Buick wouldn't be as bad (single turbo) but could still get "exciting".

 

Heh, I happen to prefer a stick myself. I liek th efeeling of control and yes, I've driven a built Auto before that could be manually shifted. My Vega had a built TH350 an d4.56 gears in a Ford 9inch. That sucker was scary fast in a straight line but I had to crawl through turns due to the tiny front tires. I loved th econtrol I got from that trans but for something I'd expect to handle well I believe I'd want a stick (shrug). If i were doing a Buick swap I wouldn't care so much about turns though - those puppies are just too much fun in a straight line to worry about corners

[Guest Anonymous]

As I read your thoughts on the 3.8 turbo Scottie - gearing is important for a manual behind the 3.8. Could you elaborate on the correct gearing?

 

My thoughts of this. I ran a turbo Datsun 1600 Roadster for a few years that made about 180 HP (using timed runs). It was a good autocrosser and road racer. I was running 3.89 rear gears and Roadster 5 speed. Turbo lag is aways a problem, but can be managed. Autocrossing I keep the RPMs above 3000 at all times to keep the turbo spooled. Most of the time I ran 6000 to 7000 RPM with just slight let off in corners. Road racing - after braking into a corner, I would apply power to get the rear out. This would get the turbo on boost (about 2-3 pounds) then coming out I get as much power down as possible. Careful throttle control is important as you say. In all I found the turbo motor guite enjoyable.

 

Now for my custom Roadster. Had my son rotate the input shaft of the T5 I have, and yep - it has a 4.09 first gear. Now that is low. Using the Z site's speed calculator this comes to: 27 MPH in 1st, 45 in 2nd, 73 in 3rd, 109 in 4th, and 136 in 5th - all speeds are at 6000 RPM. This is using 225/50/15s and 3.89 rear end. Soo, I really could use the V8 T5 or do a rear end swap to get higher gears. I don't know how much racing I will do with the custom, but I am hoping the lag will be not as noticeable because of the Roadster's light weight (2000 #). I guess this is the fun of building a car like this - bring it on!

 

Lunch is over, back to working on NASCARs cam lobe wear problem.

 

Phil

[BLKMGK]

I'll bite - tell us about the cam lobes!

[Scottie-GNZ]

Unless you have done work to the 3.8, you are wasting time revving it pass 5200, so the mph numbers for that gearing combo will be much lower. My car weighs in at 2820# (w/me) and has about 410RWHP which is a tad less than 6.9lbs/hp. With your 2000# you only need 300RWHP to match that. I do not know if your car will accelerate as quickly as mine, but for this discussion, lets say it is a tad slower. My 0-60 is in the 2.8x sec range and if you redo your numbers you are going to get about 64mph in 3rd. YUP, thats right, under hard acceleration you will have to do a 1-2, 2-3 and get ready for the 3-4 in a tad over 3 secs . You are going to be dealing with some serious acceleration here and unless you have sticky rubber, the torque is going to generate some serious wheelspin which worsens the situation. Not only do you not want to have to shift that fast, but winding up a Buick turbo that quick in the lower gears is not the way to utilize its potential. That is why I am going to a much lower numerical ratio.

 

I know you probably do not want to hear this, but my advice is to find a lower numerical ratio and the tranny with the longest 1st gear.

[pparaska]

Yeah, I thought that was interesting too - government engineer doing NASCAR R&D at work? Cool.

 

Best work related thing I ever got into was checking out the use of composite materials that Rousch Engineering (actually a small company they had bought out) was doing to quiet some desiel engines that Cummins was building for the US Navy.

 

Awesome computer modelling that took all the noise from the moving parts taking up clearance and running the motor in the computer. Actually had audio as an output. Damn thing was loud, even without the combustion noise figured in.

 

Anyway, we got a quick tour of Rousch Racing's shop and machine shop. Saw some neat stuff, to include a spare Merlin V-16 in the back of the shop for Jim's P-51 Mustang that he bought because he wanted to learn how to fly . Must me nice!

 

The race shop had a dozen or more old pristine Cobras, Shelbys, etc. sitting under covers over on one side of the shop. We got to talk to the race car engineers about the road race cars they were working on.

 

What a boon-doggle that trip turned out to be! That was my only trip to Detroit, and I never imagined I was going to get that treat!

[Guest Anonymous]

Hey Scottie - yea I may not like to hear it, but better get things sorted out now! I will start looking for the right geared trany. I hear the RX7 rear end fits the Roadster - complete rear end. They came with LSD, but don't know the ratios. I will check in to this. I want this to be a very drivable car and not a garage queen. Thanks for the heads up!!!

 

On the engine. I plan on a rebuild with good pistons, balancing, resize the rods.... Is there anything patictular I should do to make it a happy revver?

 

Hey Pete - sounds like you got a nice trip out of the deal! I just started working on the NASCAR problem. We have a Technology Transfer office at NASA that companies can get in contact with to get help with problems. We used to do the work for free, but now we charge and runs a lot of folk off - to bad!! NASA's funds are getting very tight! Did you know we are the only gov agency that makes money for the public. For every dollar spent on the space program we return 7 to 250 back into the economy through technology transfer. Independent study and not gov propaganda.

 

NASCAR's cam lobe problem. A few years ago NASCAR made the teams use solid flat lifters and not rollers. So, they started eating cams. They have tried a lot of different materials and coatings, but still can only get the cams to last one race. After one race the cams and lifters are bet to crap! The engines are run between 7000 to 9200 RPM, valve spring load is 1100 lbs, camshaft cycles during race are 1,300,000, and engine oil temps are 250 - 275 deg F. So, you see these motors go through hell. We do have some plasma sprayed coatings we will try. Remind me and I will keep you guys updated.

 

Now - Scottie, if they can get those old design V8s to run 9200 RPM, we can get a 3.8 to run an easy 6000 - right

 

Have fun all and thanks for the great information.

 

Phil

Sorry for the looonnngg post.

[Guest Anonymous]

Ye the smart one Scottie!! Many thanks!! Just when I thought I had yet another research project ahead of me - you came up with the answers. The local JY has 3 or 3 1st gen RX7s and I think I saw a couple old trucks.... and if I get disk rears out of the deal WOO HOO!

 

So, at 3.31 can I use my V6 T5 - didn't think so.....

 

I will start getting this motor apart and work on the heads. I have the body mods done so I don't need it as a pattern anymore.

 

Man, that is one fast Datsun rear

 

Thanks again

 

Phil

[pparaska]

Phil, sounds like another super quick GN powered car is in the works - Great!

 

I always tout the NASA spin off stuff. I've been reading NASA tech briefs for many years. The spin off stuff is incredible. Too bad the public doesn't see it as other than wasted money. The freaking Apollo program ALONE did more for the 30-40 year long technology explosion we're experiencing than anything else. Few people understand this. I LOVE seeing NASA do new stuff - it always pays us back BIG TIME. I see missile defense the same way, BTW. I'd love to hear more about the NASCAR deal.

 

BTW, does anyone make aftermarket heads for the GN motor?

[BLKMGK]

My Grandfather was one of the head engineers on some of the Polaris stuff working on the engines. Man some of the stories he tells! I too shake my head at the public's low opinion of NASA and the tech transfer stuff. It's really sad to look at the average Joe and realize just how far under the sand so many of them have their head's buried. I have to say that the 'net seems to be helping though, it's not hard to get some education on esoteric things just by doing a search. Heck, I learn stuff everyday! Today it was what the Mu-1 barrier" is. Look it up, pretty cool stuff!

 

Plazma coatings are cool! I've seen writeups fo rusing them on piston tops and whatnot. Talk about durable! And only a few microns thick too. I hope that one of these days costs will come down enough to make using those sorts of things commonplace. Imagine the combustion temps an engine might withstand if you didn't have to worry about the pistons melting (lol).

 

[ July 26, 2001: Message edited by: BLKMGK ]

[Scottie-GNZ]

The issue is not whether or not the 3.8L can spin to 6K, but stock, that would be way out of the powerband. With what you are doing, the right cam upgrade, and some work on the heads, it will easily make HP up to 6K. Despite all the HP this engine can make, the stock heads are simply horrible. Some mild porting, especially the bowls and port matching, does wonders.

 

The 1st-gen RX-7s came with 3.90 and 4.10. However, they should be CHEAP and if you target the ones with disc brakes they should have an LSD. Once you get one, then look for a 82-84 diesel-powered B2000/Courier as they came with 3.31 and I am sure the yard will PAY YOU to get that outta there . You then swap the 3.31 R&P into the RX-7 carrier and bingo

 

Those Japanese truck rears are incredible. Carlos, my buddy and the SDS distributor, has a 525RWHP RX-3, turbo-13B and a 6000RPM stall on a P-Glide and he has been running a welded 3.90 from a Datsun P'up for years. Oh yeah, best to date - 9.59 @ 139 .

 

[ July 26, 2001: Message edited by: Scottie-GNZ ]