fact or fiction on this performance and tuning guide?

[davey90]

I've been reading this over and over again, ever since the author posted this up on their website. But not sure if it is right, as i have no knowledge of the mechanical field. However I do understand the basic car jargons (LOL!). I'm not planning on modifying an engine, but it does get me thinking...

Anyways...you know there is a load of crap and loads of useful info on the internet. So, just wondering what you guys think about this article.

Load of bull or do you find it quite interesting and useful?

http://www.examiner.com/article/perf...and-subaru-brz

[Dorikin]

The whole point of using the boxer flat four was to maintain the overall balance of the car and keep the center of gravity low. Personally, other than minor cosmetic changes, I'll keep my 86 stock to preserve that ethos.


Also most of the stuff on there is theorycrafting. If you want to modify, the Japanese aftermarket will figure it out soon.

[sticky]

apart from attaining fuel economy targets i can't see why they have used such a high compression ratio. it really limits what you can do with the engine without spending a fortune. and i really hope toyota didn't choose the 86mm bore and stroke setup just for the sake of saying it's 86!

[Bibbs]

Originally Posted by sticky

apart from attaining fuel economy targets i can't see why they have used such a high compression ratio. it really limits what you can do with the engine without spending a fortune. and i really hope toyota didn't choose the 86mm bore and stroke setup just for the sake of saying it's 86!

86x86 is common on engines.

The 3s was a 2.0 with those specs (I4)
The 2JZ was 3.0 with the same (I6)

So it's not as if they have not got previous.

The JDM s2000 had 11.7 CR, and I still supercharged mine with great results.

[sticky]

Originally Posted by Bibbs

The JDM s2000 had 11.7 CR, and I still supercharged mine with great results.

There is hope!

[DriftEightSix]

Originally Posted by sticky

apart from attaining fuel economy targets i can't see why they have used such a high compression ratio. it really limits what you can do with the engine without spending a fortune. and i really hope toyota didn't choose the 86mm bore and stroke setup just for the sake of saying it's 86!

Myth... http://www.ft86club.com/forums/showthread.php?t=9942

Find the results out tomorrow how well 12: comp goes with a small low psi turbo

[Bibbs]

Originally Posted by sticky

There is hope!

It's all about the tuning.

The high CR gives you better results with lower boost.

Low CR would give you a safer envelope, and allow more boost.

9psi (quite low pressure) on an s2000 gives over 300rwhp. That's over a 60% gain.

I've personally seen a Turbo'ed S2000 (on a stock block) return mid 400's rwhp.

But if you want a lower CR, you can drop it easily with a thicker headgasket (cheap to fit, and a load cheaper than new pistons).

[Nafe]

Alot of that is just crap, but some does have merit as well. They seem to be over estimating power figures...
But truth be told, I couldn’t even read the whole thing... I gave up because it gave me a headache.
And no, 86x86 is because it is an 86.... it’s a common bore x stroke for 2.0l 4cyl. As well as the 3s, nissans sr20 is also 86x86.
High compression si a good thing on a N/A engine. Basically raising compression is one of the key ways to increase output on an N/A engine... In the old days they used to say “ the 3 C’s”. Cams, Compression, Carbs. More aggressive cams, Higher compression and bigger carbs. Now that we don’t use carbs it’s injectors/tuning instead, but the other two are the same. High compression engines are also more responsive, and efficient.
I, for one, am glad for the high compression
It isn’t quite as simple as putting thicker head gaskets in to reduce compression. That will work, but it isn’t a simple job on a boxer... that will be engine out. Usually to get a substantial compression drop you need the flat/dished pistons anyway, as using thicker headgaskets usually will not reduce a great deal.

[Bibbs]

I know it'd be harder on a boxer to swap the HG.

A 3mm HG dropped a non JDM F20c (S2000) from 11.1:1 to 9.7:1. That's quite a safety margin.

http://www.scienceofspeed.com/produc...c/head_gasket/

But again, it's not needed. You need a great tuner (and all the stuff that comes with it - ECU, Fuel Pump, injectors, wideband .. ).

I agree on pistons, the F20c was forged as standard (to put up with the high revving nature), so it wasn't an issue. Are the 86s pistons forged? If not, you'll probably melt something. But if it's an 86 bore, all the 3s stuff should work (keeping it Toyota).

[Nafe]

That is quite a big drop. 3mm is also a thick headgasket haha :P But hey, if it works
I know the current off the shelf HKS headgaskets reduce compression to 12.4:1.. hardly seems worth it hey?
I wouldn't count on 3s pistons fitting. Just because the bore is the same

[Bibbs]

Originally Posted by Nafe

That is quite a big drop. 3mm is also a thick headgasket haha :P But hey, if it works
I know the current off the shelf HKS headgaskets reduce compression to 12.4:1.. hardly seems worth it hey?
I wouldn't count on 3s pistons fitting. Just because the bore is the same

3mm is huge, but as the tuning knowledge has improved, the use of them has gone down.

I wasn't suggesting stock 3s pistons (they don't handle huge boost well anyway), I was suggesting the selection of aftermarket forged ones.