i allways heard that if you higher your compression ratio you can get more power.is that true.if i do that to my natrualy aspiraited L20B will it make a diffrence.what are the up and downs.and how do i do that....

if up the the compression to ur motor it will increase the horse power and there are 3 main ways to do it
1) shave the block a few thousands of an inch
2) get a higher comprssion head which means the less the cc's they are the better
3) get high compression pistons

now there is a downside to high compression the higher the compression is the, higher the octane has to be for realiability and max horsepower thats why you see a lot of dragsters running alcohol beacuase of the high compression
they run about 14:1 compression but the highest i have seen is 16:1 I hope this helps and good luck

When you shave the head on an OHC engine, the cam timing is put out. You SHOULD get an adjustable cam gear, so that you can re-adjust the cam timing.

The ignition timing and the cam timing are 2 distinctly different things.

On an L-Series any more than 10.5:1 compression will result in the need for special fuel ALL of the time.

620 dude, You need to get a mechanic to weigh your bank account before you start shaving heads, getting big cams, getting turbos, and modifying your rear suspension.

Start reading through Car magazines (although sometimes inaccurate) is the best way to enjoyably learn about cars.

i recently rebuilt my l18 and the block had a bow in it, which meant i neede to shave the block, and yes they shaved the same amount of the studs that hold the cam in place to fix the chain lag problem just a little insight on what goes on in rebuild

Going from the stock 9.0:1 to 10.0:1 will require you to use Premium Unleaded (15% cost increase), but will give you maybe a 5% horsepower increase. So instead of say 100 hp, you'll now have 105 hp. Congratulations. To learn more about compression, see this discussion: Compression = horsepower.

hey thanks guy for the advise.
WHERE CAN I GET HIGH COMPRESSION PISTIONS.AND WILL IT ALLOW N.O.S.I WANT TO RUN NITROUS LATER.LIKE 250 SHOT IS THAT POSSIBLE AND WHAT WILL I HAVE TO DO

With nitrous oxide, you don't need high compression. You can buy a nitrous system from many companies. Go out and get a copy of Hot Rod magazine or Car Craft -- there are plenty of ads in there.

The more common "nitrous shot" kits are less than 100hp. 250 shot? The L20B engine will be lucky to have 125hp. You expect to improve that by 200% ...no way.

Nitrous will cost you about US$600 to setup and US$10 per 10 second burst.

Nitrous is better suited to big money sponsored racers. Some countries will lock you up in jail if you are caught using it on the street.

When rebuilding an engine for race purposes, you need to do it as a package.

To get things done in life, you have 3 choices:
1. Figure it out yourself (requires skills)
2. Ask someone else. (requires friends or money)
3. Copy someone else. (requires nothing)

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i'm sorry , i don't mean to sound rude or offensive - and i apologise if i do.

from the number of questions you have posted recently i would suggest you have a look at some books like "tuning the a series engine" by david vizard (great book and not just applicable to a series mini engines either) and corky bell's book on turbocharging and supercharging (not the greatest book written, but the diagrams help you understand how it all works and comes together).

it seems - to me - that your are a newbie to the performance and modifying scene and you should try to brush up on how everything comes together to give yourself a better understanding of how to modify your car and what will give you the best "bang for buck".

by all means, if you have questions, keep posting - that's what forums are for. but there's only so much you'll understand without a bit of background knowledge.