flipside27

Hello first gen people! I'm very new to this side of the forums so please be gentle.
I have just purchased an 85 GS, and i have a power goal of 300whp and looking to spend around $3k. This will be built as a weekend/track car.

After reading various threads and write ups, I have come to two somewhat straight forward solutions. Either swap in a 13bt from an FC or turbo the current engine. I have pulled and installed engines in 2nd gens about 6 times, and it looks like a simple job to throw one in the FB as long as you install the 12a water pump cover and gslse oil pan (i believe thats right...right?)

In the car now, i have a streetported 12a with solid compression. I'm confident that if i were to do the blow through turbo set up, the engine could handle it for 50-75k miles.

My questions is pertaining to reliability with the turbo carb. I have little experience with carbs, but I really like the idea of mechanical tuning, and I am curious to try something different than the TII since I have had 2 already.

SO, 12a turbo guys, would you say that the 12A is a good platform for a reliable 300hp track car? Or should I just buy a FC donor car (or jdm front clip)?

Thanks!

j9fd3s

iTrader: (3)

what kind of track? 300hp is a TON for any kind of road racing, which is fine, because a 12A with turbo wouldn't be legal for anything anyways.

for drag racing, 50k miles is 1 million runs, which would take like 400years...

i agree though that doing a mechanical setup like this would be fun. you do have to be conservative though, as the carb isn't the most precise thing in the world, you also have no failsafes or knock control.

basically the thing will be as reliable as your tuning. the parts you choose matter also, if you use a stock FC turbo, and end up with unstable boost, or you have poor temp control.

flipside27

The car will be set up for time trials and windy road conditions. I have a very lengthy suspension parts list that will be completed before I start tinkering with the engine work.

As for tuning, I do have an AEM Uego wideband I would like to hardwire and set up for the carb. Thats only possible to me in theory, and through searching I have only found a few people who have uego widebands on a carb set up. If someone could confirm this possible I would greatly appreciate it!

That being said, I found this thread (ENGINE) How to build a high output 12a turbo without blowing up your motor and at first it seemed to have solid information, then everything quickly seemed to be mixed up amongst the members and I dont know what the true actual numbers / reliability procedures are for a 12A turbo set up.

It seems that every car with this set up is hit or miss, and i have yet to find a 12at set up to last more than 3 years. Given that 4 months out of the year my car will be in storage, it might extend my time to 5-6 years if i drive it casually.

it also sounds like anything past 10lbs of boost is starting to push the 12a limits. I suppose my power goal would be more realistic at 250-300whp for the sake of reliability. OR just go with the 13bt swap like many other people.

flipside27

and even though all this information is grey, and i dont quite know what I'm doing, something still tells me that i should try the 12a turbo
Especially now that may of the parts needed are available through Rotaryshack

j9fd3s

iTrader: (3)

thats what you think! do some reading about rotary shack.

j9fd3s

iTrader: (3)

when you try to triple the output of any engine the choice of parts and the tuning becomes really really important.

you can get away with things @100hp that you can't @300hp. secondly most people with big hp turbo cars try to run too lean and with too much timing, so they have no margin if they get a bad tank of gat or its a hot day or something.

you're also adding the carb to the setup, which has no safety provisions.

blow through 300hp 12A has been done before, you just have to be careful and work up to it

flipside27

Oh man thanks for the heads up. I just googled Rotaryshack review and this Ripoff Report was the first listing. Back to the drawing board!

pinoyremix

I have a aem uego for my carb setup

Rotor_Venom08

iTrader: (3)

who not run itbs and a megasquirt? ive seen stock healthy engines with exhausts on itbs pushing 160 yours is street ported. with some tuning you should be able to get plenty then on top of that turbo. pshhh. if i had the cash thats what i would do. fuel inject the 12a and go turbo., bring it to the 21st century where it belongs

MazdaMike02

iTrader: (4)

I would get an Innovate wideband, theyre priced well and have a good rep.
Also you may want to look into an MSD 6BTR, it is able to retard timing 1 degree for every psi of boost.

Also check out the AEM Failsafe Wideband, it has a programmable output trigger than activates at a target AFR. You could use this to trigger meth/water injection to save your motor from going boom.

Ive been considering a blow through holley setup on my 13b. And my main concern is the lack of protection with a carb.

midnight mechanic

300 whp? but what about getting it to the pavement? people swap in mustang 5.0 differentials when they stuff a v-8 under the hood.

ArmyOfOne

iTrader: (12)

It is all very doable, as was mentioned above you just have to run conservative and stay on top of your oil changes. I ran one this past year on mine at 10-12 psi for drag and street driving. Definitely taught me a lot! If I can do it on pump gas without an intercooler then a complete setup will be reliable.

flipside27

All very awesome words of encouragement and advice. Still playing with the idea. So far it sounds like a lot of fun if i keep it conservative. And Happy lunar new year everyone!

GySgtFrank

iTrader: (4)

My $.02.

If you've run S4 FCs you already know about higher boost levels and cracked irons. The 12A is probably going to be even more vulnerable. For 300hp you'll most likely have to be running close to 15lbs. or higher boost levels, which may be a bit much for a 12A. Lean conditions will kill a turbo engine quick. With fuel slosh in the float bowls as well as the previously mentioned lack of precision with carbs it sounds like an expensive recipe for disaster in a car used on a road course.

My suggestion would be to go with either an S5 FC engine or an REW with some type of injection to meet your stated power goals and still have the durability to complete a race. You can build up the 12A 's strength somewhat, but it's not real cheap and still leaves you with the fuel delivery problems.

flipside27

Thanks gyssgtfrank. I'm going back and forth as to what I should do. What your saying makes a lot of sense also.

Its coming down to reliability and longevity. Although a lot of people here have had positive experiences with 12a turbos, I dont want to invest time into a set up that will inevitably be less reliable than a 13bt swap. I might for the time being install a weber 48 and enjoy the car for what it is. Then when the time comes, do the 13bt turbo swap.

I'm very comfortable and confident with the swap as well, given that I come from the FC side of things and have experience with the engines/harnesses.

GySgtFrank

iTrader: (4)

Agreed. You can have a lot of fun NA with the Weber until you can save up the bucks to do the turbo setup correctly.

flipside27

I also just found this chart that claims a potential 280hp with peripheral porting 12a NA with a weber carb. Racing Beat has an awesome reputation so i dont question the possibility, but has anyone ran a set up and dyno tested to support this? If so this would be a very considerable option for me. http://www.racingbeat.com/manuals/intakeguide.pdf

j9fd3s

iTrader: (3)

this is what the IMSA GTU cars ran in the 80's, basically. the factory 12A peripheral port was rated @265hp@9000 with a carb, 280@9000 with fuel injection.

i'm running a P port 12A with a weber, noise is a problem, but on the track its great, with the stock 12A air cleaner, and ***** exhaust i think i'm putting ~175hp down, peak power is at 5500, so i do think there is another 50hp easy by removing the air cleaner, and building a better exhaust.

its also tame, idle is ~1000rpm, it drives about like an FC with a bad tps, so if i could smog it, i'd street it. it even gets better mileage on the track than an FC does