4ag building. Good ideas vs Bad Ideas

[DeftAnesthetik]

just wanted to start a thread to beat out some of the final details. not interested in discussing "what 4a is better" as its mostly a matter of opinion and usage, plus I plan on using mostly what i have lying around.

so the story is that i am building a 4a (of course) i plan on doing either one of the following:

1: twin charged with sc14 and a mid-large sized turbo
2: twin turbo with 2 mid sized turbos
3: twin charged, twin turbo with sc14 and two turbos.

some facts

I am using a late model block (SilverTop) with oil squirters and Forged crank. I will be boring this block out to 82mm as well i will be balancing and blueprinting the entire bottom end. Not too sure on rods I have the S/T ones but will upgrade to some H-beams if i find a good deal. Pistons will obviously need to be replaced, hoping to get some Toda's but again any good set of forgies will do. I am aiming at that 8:1 to 8.5:1 comp.

I have a largport head that will be worked over. O/S and Hardend valve seats, angle job, ported etc. looking to get some cams but will keep them fairly mild 260ish and that 8.5mm lift. (keep from switching to shim unders if i can)

this is going into my '86 mr2 so i may have some issues with space but i am not afraid to fabricate.

what i would like to discuss:

I have my ITB's from the S/T...... any thoughts on forcing air through these?

turbos.... better to have two of the same size or one larger(max boost) and one smaller (less lag)

flywheels. i'm thinking something heavier to keep idle decent and revs up.

well thats where i wanna start, if im beating a dead horse just post me a link to previous discussion/site.

thanks in advance

[RO11LR]

bloody seppo's !

[Mr Revhead]

right.


quite an idea you got going there.....
ill skip the twin charge bit....

no problem with the ITBs and boost. black top ones are bigger.
dont forget a dump/by pass valve.

[DeftAnesthetik]

right.


quite an idea you got going there.....
ill skip the twin charge bit....

no problem with the ITBs and boost. black top ones are bigger.
dont forget a dump/by pass valve.

good news, yeah i know BT are bigger but i have the ST's.

[Ben Wilson]

Use the standard inlet and use a 3S-GTE throttle body. Fit one well matched turbocharger and enjoy.

The time you'll gain getting this setup working will put you streets ahead of any multi compressor setup. Instead of buying lots of cheap components, but as few as possible good quality ones.

Also - All those compressors and plumbing are going to weigh a lot, that will really hurt the handling of a mr2 (trust me on this one)...

Single turbo + 12 months development > Twincharger with no development.

[wilbo666]

Fit one well matched turbocharger and enjoy.

The time you'll gain getting this setup working will put you streets ahead of any multi compressor setup. Instead of buying lots of cheap components, but as few as possible good quality ones.

ZOMG pick this answer...!

Cheers
Wilbo

[jfallen]

buy Toyota ceramic coated GZE pistons. they seem to take a fair beating, and at ~$450is they represent great value.

Twincharging is gennerlly nasty, complex and painful, be rewarding if you get it working. If you're set on a twin charged set up go as simple as possible. have the throttle plate(s) after the super charger, have 2 bov's, 2 intercoolers and run the turbo into the supercharger. no bypass circuts, no excess piping.

better option would be to buy an ebay T25manifold and strap on a garrett GT28RS or GT2871R or cheap out on an S15 turbo. some FC or GTR injectors, spend the difference on a good computer to run it all.

Jordan

[DeftAnesthetik]

I have been thinking about twincharging for quite some time and although complex and expensive I kinda have my heart set on it. I will have all winter (october through march here) to build and fit. I am fairly happy the way the current setup is NA bigport pushing 130hp but I have been building the car up for some drag/autocross and just don't see it keeping up to some of the newer cars. I know turbo technology has come a long way and the lag factor is less than it has ever been but I want the car to shine all round on the track and still be drivable on the street. Feral was working on a twincharge setup (talk to me if your around) and this is after he had run the turbo setup......... I suppose i still can be talked out of it but i know eventually the itch will creep up again. I have a few drawings made up of some setup ideas i will scan them in and get them up here for critique. GZE ceramic coated pistons--- Can you get them for 82mm bore or do they just come in std 81mm?

[fixeruperer]

81.5 0.5 o/s, aswell as standard

[oldeskewltoy]

hmmmm for parts..... Arias makes a sweet piston... 8.5 to 1 if memeory is right.
Have you seen the 267hp 20V silvertop from the Uk? It runs a Rotrex supercharger....
http://www.hachiroku.net/forums/showthread.php?t=7623
nice compact design.
For cams the "shizzle" is Colt cams "Tri-flow" cams. measure 261 total duration with a 223 [email protected]" lift, lift is 8.28mm In essence... Tri-flow is one of the two lobes opening a few moments before the 2nd lobe opens the 2nd valve. both cams reach full open and close simultaniously.

Just a few newer things floating around in recent years...

[jfallen]

Autocross and drags are all clased based, and there are few cars in the NA1600 class that can beat the MR2.

Jordan

[DeftAnesthetik]

hmmmm for parts..... Arias makes a sweet piston... 8.5 to 1 if memeory is right.
Have you seen the 267hp 20V silvertop from the Uk? It runs a Rotrex supercharger....
http://www.hachiroku.net/forums/showthread.php?t=7623
nice compact design.

Just a few newer things floating around in recent years...

OK, I might be rethinking the sc14, those units look much lighter and smaller. run one with a twin turbo setup and you might be able to convince those who dont know any better that your running a tri-turbo.

[wilbo666]

OK, I might be rethinking the sc14, those units look much lighter and smaller. run one with a twin turbo setup and you might be able to convince those who dont know any better that your running a tri-turbo.

Yeahhhhh that won't add much weight



Cheers
Wilbo

[BeRad]

Thats 2 small turbos, 800cc per turbo?... im going to leave this one for common sense to handle.

1, 2 or 10 turbos the air to drive them has to come from somewhere 10 turbos wont make it go faster than 1 turbo, quiet the opposite usualy.