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tomking
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2,498 Posts
Discussion Starter · #1 ·
I am a new (again) Opel owner with a 71 Gt. I wish to do some racing with it as well as drive on the street. The type of racing would be closed course paved tracks as I am not interested in the rough and tumble motor cross stuff. My question is what can I do to the engine besides porting in order to increase torque and hp but still stay in whatever class needed in order to race "stock". IOW how large can the block be bored? Are you limited to .040 over or something? Or can you go to the 95mm size? effectively making it a 2.0? I will probably build up a 70 engine for racing as it already has higher compression and keep the 71 engine for street. I am just looking for advice in order to begin with the engine. Thanks for your help.
 

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Super Moderator
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Interesting question. However, I wonder if you have 'racing' truly in mind or are simply interested in running the car at some track venues? If you merely want to get in some track time, there are many clubs which hold 'time trials'. These are controlled events, with no passing in the corners, and even bone-stock vehicles can participate with no modifications. You'd merely need a safe car (good brakes and tires, etc.), and a helmet and safety belt.


In order to truly race however, the car may lose much of its street-worthiness. A full rollcage, much stiffer suspension, proper racing tires, a racing seat (fixed-back), racing harness', etc. There's always a great chance of the car getting damaged by contact with other cars. Race drivers are aggressive by nature!

Regarding allowed engine modifications, it depends entirely on the class you decide to run. The class I'm running, SCCA's ITB, essentially allows a stock engine up to .040" overbored, up to .5 more compression than stock, NO porting, stock cam, Weber 32/36 carb, and and ignition and exhaust allowed. That's it. Next up would be Production class (top cars cost 100k), and then GT-4 after that (similarly expensive). They would not be street legal at all.

I'd probably stick to modifying your street car to whatever specs you want, and then just run it for fun in a time trial. Certainly less expensive than all-out racing, and you can still get some thrills without wondering if the car is gonna get wrecked every raceday.

BTW, the best place to start on this project is the driver. Try a driving school first. At the very least, you'll learn something. If it still interests you, then work on the car's brakes and suspension. The engine means the least on the track. Too many people forget that the corners mean more than the straights in road racing.
 

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tomking
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2,498 Posts
Discussion Starter · #3 ·
yes Bob it is probably some track time that I am looking for as I am not interested in spending that kind ofmoney nor installing a cage etc. If it is just track time and club racing then would I be correct to assume I could do practically anythiing I wished to the engine then? using 2.0 pistons for example? polishing and porting too? I have a weber carb on it but not sure which one. Plus I just installed the big brake package from OGTS with green pads. Am finishing up all poly bushings now. I checked with Cameffects on their roller rockers and might be interested in them too. What do you recommend about them? I also have the lightened flywheel on order from UR along with the clutch stud from you. BTW just tell me when you have them made and send address to mail the check. Thanks.
 

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Okay, I now understand that you think 'club racing' is track testing only. SCCA considers 'club racing' to be amateur racing, but still requires all safety equipment, etc. Anything you do that does not require a rollcage, fire suit, etc....will be considered a 'timed event', but not racing. If there's racing going on, then insurance costs go through the roof and so do the safety requirements.

Most clubs have time trials that you can 'run what you brung'. If so, remember that doing a lot of modifications may move your car into a classification where it's no longer competitive. For example, I had to run my old street Ascona in the top class because of my modifications, even though that meant running against Corvettes, NSX's, Porsche's, a few Ferrari's, etc.

I say go for it, build the engine the way you want for the street. But put at least as much time/money into the suspension, and don't skimp on tires. Proper racing tires will net you more performance than 40 more hp......
 

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Rally, or rallycross? Rally is high speed on dirt roads. Rollcage and skidplates, etc required. A stock GT would last maybe 10 minutes before suspension failure.

Rallycross is relatively low speed on dirt, like an autocross. It (a stock GT) would understeer horribly, and with stock tires and suspension, would probably end up dead last every time. It would run in the rear wheel drive class. Classes include AWD stock, AWD modified, FWD stock, and FWD modified, then RWD. They don't seem to care if the cars are stock or modified in RWD, generally RWD cars finish last or near last regardless, so they lump them all together.

Bob
 
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