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tinytim
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 Posted: Mon Sep 26, 2005 8:55 am Post subject: How do I tune a N/A SOHC 4G92 EFI? |
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How are you supposed to go about tuning this engine for performance? The particular engine in question has about 140K (miles) on it, however the maintenance requirements have been adhered to all belts have recently been changed and the engine is serviced every 3K miles.
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tinytim
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| Posted: Tue Sep 27, 2005 6:33 am Post subject: |
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Anyone?
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chinaman
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| Posted: Wed Sep 28, 2005 9:31 am Post subject: |
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tinytim
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| Posted: Fri Sep 30, 2005 7:47 pm Post subject: |
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Saw your offer chinaman... want to get the engine properly tuned before I consider bolt-ons. So yuh mean nobody here have any advice?
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chinaman
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| Posted: Mon Oct 03, 2005 8:05 am Post subject: |
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| no scene man |
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Doctor X
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| Posted: Thu Nov 03, 2005 9:29 pm Post subject: |
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| anyone ???????? |
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MG Man
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| Posted: Wed Dec 05, 2007 6:49 am Post subject: |
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| tinytim wrote: | | Saw your offer chinaman... want to get the engine properly tuned before I consider bolt-ons. So yuh mean nobody here have any advice? |
good approach
Make sure your engine is properly maintained and serviced:
The basics include cleaning / servicing injectors, running good spark plugs, making sure your plug wires are in good condition, good quality air filter etc. Also a good idea to fit a good grounding kit.
One thing to remember, more expensive plugs and wires do not add HP....they simply make sure you get what you supposed to be getting
Once you do all that, have the car dynoed to see exactly what you are producing.
Now, assuming yor car making the right factory number, you can begin bolt-ons
The basic principle is this: to produce more power, you can burn your mixture more efficently, or burn a bigger mixture. Since we assume your engine is optimised, we can now look at ways to get a bigger combustion.
Right. The basics of a bigger bang is more airflow. The basic upgrade is a FIPK (K&N Fuel-Injection Performance Kit) or CAI (Cold air intake) THis comprises K&N filter and a relocated inlet tract, to make use of colder air forward of the engine. This makes your engine inhale better. To exhale now, you need to run a good tubular exhaust manifold (aka headers or extractors). I would stay away from the local stuff. You cannot go wrong with aftermarket form reputable suppliers. You have two choices: 4 into 1 or 4 - 2 - 1
4 - 1 gives you more revs and top end HP, while 4 - 2 - 1 gives you better midrange torque, which is better for street applications. Keep in mind a good intake / exhaust system will be good for 7 - 10 bhp MAX, since you will still be running on your stock map. To optimize the extra air, you would need a chip upgrade or programmable ecu.
Right. The other way to make some incremental HP gains is to make your engine ancilliaries more efficent. An underdrive pulley is good for 2 or 3 hp. Things like performance alternators and water pumps also reduce parasitic losses, and are good for another hp or two.....
ONce you really get into the thick of things, you can look at head work. As old school as it sounds, a good porting works wonders. Some of it you can do yourself, some are more tricky, so here goes:
Start with matching your ports and manifolds. Simply put, when u bolt your manifold onto the head, in most cases, the holes don't line up exactly, and you have overlaps and restrictions.
Take some paper and make a template. Mount it on the block, using the mounting studs, and rub with some carbon paper to make an impression of the ports. Line it up on the manifold, ideally if u can bolt in some studs so u get an exact lineup and rub again. Wherever you see offset port impressions, you need to grind away some material. Always better to grind the manifold first, then the head if needed.
Easy
Not so easy is head porting. The basic principle is to round off any casting edges and sharp corners, and open up the airways. Hit and miss nice you won;t be ale to gasflow the head, but it should still see some gains. Next, you want to open up the combustion chamber, ie the 'roof' of the head where the valves are. Best basic approach is to clean up the area around the valve guide, ie the hole where the valve goes in. For good illustrations of what to do, see "how to build horsepower" by David Vizard
(you will need some good tols for this)
One last thing, buy the book "Engine Management Systems" by Dave Walker
The internet can be a funny place, and this book should be considered your bible before you ask for any advice!
I cannot stress enough how important these books are. They give you all the answers you seke to find on the internet, without all the speculation
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