bobafett

ok, i am very new to this custom turbo stuff, so bear with me. i have read up a bunch on this forum, as well as DSMtalk, and the regular homemadeturbo.com page..

anyway heres my situation:
i have an 86 honda accord, which has an a20a3 2.0 engine (same as the sohc preludes i think) . SOHC non vtec, 12v... nothing fancy... not very much aftermarket either... anyway i am planning on running a turbo, but i have some very specific requirements, and i wanted you guys to point me in the right direction according to my plan!

right now my engine has 230,000 miles on it, but runs great, nevertheless, i am counting on this engine dying soon once i boost it. my plan is to run low boost (6-8psi) on stock internals until it blows. when it blows i would like to swap in another engine with forged pistons etc so it can handle a little more boost (maybe 12psi, no more than 15),

my car stock has 8.8:1 CR, which i figure is a good start, its lower than the 88-89 accords, which have 9.3 i think... these accord supposedly handle boost pretty well, since they have steel heads instead of aluminum...(or so i am told)
anyway is it necessary to lower the CR even more, to say 8.5:1, since i am gonna be buying forged pistons, or is this not needed?

i have a friend who can make me a manifold, but of course first i need to decide on which turbo to run. at this point i am thinking that a DSM 14b would be perfect.

the most important thing for me is safety and reliability. for those reasons i want to make sure my car is tuned right, and is a safe daily driver. (this may not be 100% possible until i get a rebuilt engine, and i understand this). i want to run a FMIC, because as i understand it, it will help keep detonation away, since temps are lower, and they also look damn cool.

i dont know which direction to head, could you guys help me get started?

another thing i wanted to know is if i should get a S-AFC, or would that be stupid? i am really new to all this as you can probably tell, but i would love some help from those of you who can provide it!

Rolla1990

Well, I'm glad that you've been doing so much reading up!

The engine you have had a lot of miles on it, but it might be able to easily handle 6-8 psi, since the compression is only 8.8 :1 . That is extremely low for a NA car. A 14B turbo will probably be too small for a 2 liter honda engine, especially if you're going to get a better engine and switch the turbo kit over. You should probably go for a t-3 or even a t3/t4 hybrid, if you want to spend the money.

If you use a S-AFC, your car will be very tunable, especially if you use the DSM injectors. I have never used a S-AFC, but everybody and their mom uses it on their boosted hondas.

Your car IS fuel injected, right? If it's not, then forget the whole turbo idea until after you get a different motor...

All in all, it sounds like you know what you're talking about and you have a reasonable idea of what you want! Good luck!

bobafett

thanks for the reply rolla! and im sorry about your engine, i just read about the bad news!

yeah my car is fuel injected. it was one of the first years of it though! most 86-89 accords are carbed

yeah i was surprised at how low the CR is, but it did recieve a bump up to 9.3:1 in 1988. this current engine is still happy, but i need to change my timing belt, its been *GASP* about 135k miles!!! after that its ready to rock again.

why would you say that a 14b would be too small for a 2-liter honda engine? the 4g63 is 2.0 and it supports a bit of modding before its pointless to have a 14b (then again the DSM guys also say that the 16g turbo should have come stock! lol)

other than a S-AFC (which i would love to use) what should i get for engine managemenet? with DSM 450cc injectors, and a S-AFC (no vtec here) is there a point in buying MSD BTM? and if i had all those, what other steps should i take to ensure a happy engine? i would rather have low boost and make less power, but know that i am playing it safe!

AND, when i put in a rebuilt engine it will be another a20. they are cheap, and i dont want to deal with the hassle of a swap. the only drop in swap for my car is a b20a JDM accord engine. the prelude b20 will not work. and its damn near impossible to find the b20a with a manual tranny!

the next cheapest solution is a b16, which costs about 2000, for the parts needed to fit the engine in, not including the engine tranny ECU etc...

for those reasons i am stcking with the original engine. there is a guy in englishtown NJ running 12's at 18psi, so i am very confident that i can boost this sucker. the only other turbo a20 i know of ran like 23lbs, but he has never taken it to the track, and he is currenty doing some major work to his fuel system.

**** ok i thought of some more questions:

what is the lowest ammount of boost that could be run? and is there a point in doing so?
if running like 6psi would i need to upgrade the fuel system, or should i still be ok?

Semnos

lowest amount of boost .... 0 psi
get the S-AFC, 450cc injectors and do the hack with 8.8:1 comp ratio i would boost the sucker to the limits of the s-AFC hack that's like 9,4.. psi on old honda map I was told. With that kinda compression ratio i wouldn't worry to much about detonation especially if you get a FMIC. Damn 8,8:1 comp that safety and reliability enough for boosting that low(6-8 psi).
You can get a MSD BTM if you want..just to be set for the new rebuild engine.
If i were you i would deffinately get the s-afc and the 450cc injectors it's a must if you ain't going to FMU way..you need bigger injectors.
And as for the rebuild engine i would bump up the compression a bit higher. You can get much more power with a higher compression and with the forged bottom end it van stand all the boost you can give it with the S-AFC hack. Cause you ain't going any higher than 10 psi with the S-AFC hack, so a higher comp will get you some more power.
If you wanna boost higher than that..well you will need to go to some sort of standalone fuel management system.

bobafett

i am a bit unclear about what "the hack" is...

semnos youre saying to get 1)S-AFC, 2)450cc jectors, 3)hack (with max of 9.4psi)

when you refer to FMU, is that a specific device, or just anytype of fuel management unit? (which is what i understand that to mean)

i didnt know that 10psi is the most that could be run with a S-AFC. and when you refer to the S-AFC "hack" youre just talking about using that safc system right? since its essentialy hacks the air/fuel tables... right?

i know i am showing my newbieness by asking such questions, but obviously its important that i have a solid plan before i get started.

from the posts i have read, i was under the impression that S-AFC was better, and FMU hacks were the cheap way to go, with limited tuning. or is that just specific FMU's?

are you saying there is no way i can use an S-AFC if i ever want more than 9.4psi? (not that i will be even close to those levels right away! )

sorry for the barrage of questions... but you guys know your ----!

guido_kp

the FMU that Semnos is referring to is a boost dependent device that raises fuel pressure relative to boost, they arent as easily tunable as the SAFC, using different ratio disks to tune. the increased fuel pressure forces the injectors to squirt more fuel. the SAFC hack requires the SAFC and 450cc DSM (or equivalent) injectors. by using the AFC to lean out the injectors to approx -35%, you get a decent fuel map, and in the process also prevent the stock MAP sensor from ever telling the ecu that boost is present. the stock MAP is probably a 1 bar sensor, good for 14.7 or is it 14.5? psi. so you can only limit it from sensing so much boost, in this case its ~9-10 psi according to Semnos. youll have to employ some other form of trickery after you reach that amount of boost. that is the hack, in simplest terms. the thing with the hack is, since youve deceived the ecu that much much less air is flowing through the engine than really is, the timing gets way advanced, and also needs to be controlled accordingly.

bobafett

oh ok, now i understand why somebody was asking about using a 12:1 ratio... i read that thread, and didnt really get it... so thats his FMU ratio for a specific level of boost. makes sense to me.

as long as i can run my car with the S-AFC for now, and be fine until like 9psi i will be fine... i have a lot to learn before i try cranking it that high.

ok. lets assume my engine is stock, i have all the turbo hardware:manifold bov FMIC turbo, its all happy.
then i buy a S-AFC and 450cc injectors. could i run low boost at this point? he said to not worry about the msd BTM until i am running higher levels of boost. i just feel nervous about running nothing but 450s and S-AFC to keep my car safe, even if i do have 8.8:1 CR.
isnt there something that needs to be done with timing? i assume the SAFC only changes fuel delivery, not timing... thats why i assumed that the BTM would be essential. but thanks for your help so far, i am really starting to get a better grasp on all this!

BTW, is there any advantage to running S-AFC on my car while it is still naturally aspirated? i wouldnt mind learning how to tune with it before i have the turbo, especially if i can squeeze out a couple HP! :P

guido_kp

right, the FMU disks raise the fuel pressure according to boost. like a 12:1 disk would raise fuel pressure 12psi for every 1 psi of boost. the msd btm is probably not essential at this point, with only low boost, but it wouldnt hurt to have it eventually. and youre also correct about the afc being strictly for fuel. you could run it NA and maybe gain a bit, it would depend on if youve done any performance mods that would benefit from additional fuel delivery. if nothing else, hook it up, get familiar with its adjustments, and have it mastered by the time you get boosted.

bobafett

at this point i dont really have any special mods. just intake headers and exhaust. i am redoing my exhaust next... going from 2.25 cat back, to 2.5" with high flow cat and better muffler... i may or may not bother with CAI, i can get one for like $40 shipped so i might as well give it a shot right? i was thinking about a cam, but i dont want to waste the money since i will want a different grind once i am boosted.

from what you are saying i would assume that with the turbo slapped on my car, and low boost (say 5-6psi for starters) and just injectors and SAFC i could safely drive my car around daily! msd may be just an extra treat.

what about things like boost controler? turbo timer? or those really necesary or just luxury items? i know i want both eventually, but hey, i am on a budget, as are most HMTers i am sure!!

now if i could just decide which turbo to get!

guido_kp

with the mods you mentioned, the afc would be of some benefit, and its potential would be fully realized when you install your turbo. a CAI would help for the present, and you can always recycle it into charge pipes when the time comes. the msd would be a treat, and along with a boost controller and a turbo timer. boost controller is good for raising boost, not something youre going to want to do right off, and the turbo timer keeps your car on for a user defined amount of time after you get out. helps the oil circulate, keeps it from cooking to the turbo bearings after a hard run and a fast shutdown. if you want you can sit in it and let it idle for a few mins before you kill it, its the same. if you get a turbo with a water cooled chra then the water will also help cool it along with the oil.