2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.
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Old 02-20-02, 08:40 PM
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Got my new engine today!!!

Mazdaspeed7 and I pulled an engine out of an 86 sport today with 120000 miles on it. now i get to mod the entire thing. any suggestions on things other than basic rebuild and porting, to the actual block.

Justin
Old 02-20-02, 10:17 PM
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S5 internals! Higher compression, etc.
Old 02-20-02, 10:27 PM
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Justin, how would you like to be the guinea pig for some high compression n/a rotors? I was thinking about sending my extra pair to my uncle and have him fill the recessed part some to bump up the compression. I just need to figure how much displacement to cut to raise the compression up to lile 11.5-12.0 Every point increase is good for 4% more power, so 11.7 would make 8% more power than stock S5 n/a, and almost 10% more than S4 n/a rotors.

Ill have some pics of the engine tomorrow, along with pics of my hood Justin paid ~$270 for engine, ECU/harness, coils, airbox/afm, and a few other little things. The engine appears to have decent if not good compression. It turns over easily, with very distinct puffs of air.
Old 02-20-02, 10:51 PM
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damn! I need an S5 engine.......or rotors.....you got the entire engine for 270 bucks! Damn what a steal
Old 02-20-02, 11:47 PM
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I got an alum hood in nearly perfect condition for $75. The only problem is the paint is a little rough from sitting otuside for a long time. Other than that, perfect.
Old 02-21-02, 01:09 AM
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i dont like the term guinea pig. show me something to make me feel better about testing on my car.

would he fill it with ceramic??? i do like the idea but i need to see some other guys experiences with high comp rotaries. i would have to use high octane gas but i dont want to be pinging on citgo 94. that would suck. if i did that i woudl definitely get the hurley 3mm. i just dont want my engine to eat one. hmmm......

i wanna know how much power (ballpark estimate) a s4 street ported, 12.0 compression, exhaust port with full exhaust and cold air intake would make???

i want some opinions

Justin
Old 02-21-02, 01:05 PM
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any more ideas......bump
Old 02-21-02, 03:53 PM
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anyone???????????????????/
Old 02-21-02, 04:49 PM
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Go with 3mm seals.

12:1 compression... Damn.
Is that a resonable figure?
I would look at some N/A race engines... seeing what compression they use.
With that kind of compression I would definately go with 3mm apex seals... You will be running a very high risk of detonation if you aren't running 100 octane all the time.
3mm seals can handle quite a bit of detonation- one good ping can break a 2mm, while a 3mm will take a LOT of abuse. Worth the insurance I think, though they can break, but you have to pretty much TRY to do it! They also seal better at high RPM's because of higher centrigugal force exerted outwards onto the housing by the seal.
Oh- and FD side springs- they are much better.

You need a milling machine for that though- the groves have to be perfect. Any machine shop would do it- rotary "specialty" shops charge a ridiculous amount, up to 800 bucks!!!!!!!! It is really just a very basic machine job, and should cost about 100 bucks or less, that's how I got mine done. Just another example of "specialty" overpricing.

As for HP figures, I really don't know, but with mild porting, and you'll want a BIG exhaust... Defnitaely over 200 at the flywheel. I definately wouldn't expect any lower than that, but I am not sure how much more.
Old 02-21-02, 06:07 PM
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200???? sounds good to me. Adam, if you can get it done well i am game but i dont want chunks of metal flying off my rotors.


Justin
Old 02-22-02, 09:58 AM
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i bump to much?????
Old 02-22-02, 12:39 PM
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Re: Go with 3mm seals.

Originally posted by Bambam7
12:1 compression... Damn.
Is that a resonable figure?
I would look at some N/A race engines... seeing what compression they use.
With that kind of compression I would definately go with 3mm apex seals... You will be running a very high risk of detonation if you aren't running 100 octane all the time.
3mm seals can handle quite a bit of detonation- one good ping can break a 2mm, while a 3mm will take a LOT of abuse. Worth the insurance I think, though they can break, but you have to pretty much TRY to do it! They also seal better at high RPM's because of higher centrigugal force exerted outwards onto the housing by the seal.
Oh- and FD side springs- they are much better.

You need a milling machine for that though- the groves have to be perfect. Any machine shop would do it- rotary "specialty" shops charge a ridiculous amount, up to 800 bucks!!!!!!!! It is really just a very basic machine job, and should cost about 100 bucks or less, that's how I got mine done. Just another example of "specialty" overpricing.

As for HP figures, I really don't know, but with mild porting, and you'll want a BIG exhaust... Defnitaely over 200 at the flywheel. I definately wouldn't expect any lower than that, but I am not sure how much more.
It would be nice if any of the racers ran something besides stock compression, but theres one little problem. NO ONE sells high compression rotors. I lloed for months and months, and no luck at all. I *may* be able to get it done custom for a good price. My uncle owns a full machine shop, and does lots and lots of car stuff. But I havent talked to him about it yet, I was just throwing out possibilities.

11.5-12.0 CR would be safe at a conservative ignition timing, as long as the engine had adequate cooling in that area. Im looking into ways to increase the cooling efficiency around the spark plugs(big hot spot). RB and a few other places machine grooves into the metal around the spark plugs to help it cool better.

11.7 CR rotors would be good for 20-25 RWHP OVER S5 rotors in a PP motor.
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