shone190

Hi everybody.

I'm from Europe (Serbia) and participating this forum for year and a half. Please do not blame on me because of my English
I have Trans Am GTA 1988, 5.7 TPI completely stock, with only 50.000 miles on it, fresh rebuilt 700R4, and want to build up the engine for about 100-150HP. I like turbo cars and want to do it with turbocharger. I was reading a lot of your posts on this forum section, but I don't have enough knowledge and need some answers.
I'm not a racer and won't drive races with my car, but simply love to have car with turbo power , and want to build one.

My questions are:

1. Do I need twin turbo setup for extra 100-150HP or I can do it with single turbo?

2. Do I need some ECM modifications if I put single/twin turbo?

3. How much boost is safe for this engine and how to calculate this if I have twin turbo sistem.

4. How much HP gain I can expect with single/twin turbo within safe boost range for my engine?

5. Is this fictional setup (about 350HP) safe for my fresh stock rebuild 700R4? I mention again that I won't drive races

Most of parts (headers, intercocoler, pipes...) I can buy/make in my country. Regarding turbocharger, I would like to buy something like this:
http://cgi.ebay.com/ebaymotors/t3-t4...Q5fAccessories

I know that most of you will tell me that this is china garbage, but for my needs, I think it's completely enough.

Thank You all in advance.

Best regards,
Nenad!

giszo

#2: Yes, you will definitely need ECM tuning after you add turbo(s) to your current engine.

shone190

You mean that I need to buy new PROM or there is option to "flash" current?

Is there any shops/stores that sell/flash Proms?

Sorry if my questions are stupid

giszo

It is the best to buy new PROMs and leave the current as is, so you can go back to it anytime you want.

There are shops that sell PROMs, but you should flash your own ones. There are other options to avoid PROM flashing all the time and still stick with the stock ECM. Check http://www.moates.net/ for example.

bduffey723

#1.. u can get just enough boost with one big turbo. but if ur like me and think twins look cooler u can also go with 2 smaller ones and get the same boost as the one large one. and with that turbo u are looking at ur tranny will be just fine if its been rebuilt and u dont plan on racing.

shone190

I think twins look cooler too What do you think, is this turbo from e-bay adequate for twin turbo setup?

What is the base problem with stock ECM and twin turbo setup? Will it work at all?

giszo

I don't think that stock ECM is prepared for boosted applications.

If you are not really familiar with these things maybe it would be better to ask a shop do all the work for you or you have a long list of stuff to learn.

shone190

In my country it's hard to find USA car at all, not to mention the TPI ECM tuning

Is there any kind of "shops" where I can buy PROM which is already reprogrammed for turbo setup, or to send mine for reprogramming?

giszo

You can have a pre-programmed PROM for you application through mail but I believe that the last pieces of fine tuning can be done only with having and driving the car.

As I see you live in Belgrade, around 200km from Hungary. I know at least two shops in Hungary who does USA car building, tuning, etc. if you're interested.

Orr89RocZ

iTrader: (20)

Keep it simple and do a single turbo setup. Buy a master power T64 or T70 with .96 a/r housing Ptrim turbine.

Swap to a 91-92 camaro/trans am computer...do the repin, you can keep your current wiring harness. Just need to add in a few wires for a MAP sensor.

Run code $59 in the chip/prom to run this motor on boost. Thats the proper way to do things.

Turbo for 350hp is not worth the effort, you can do that with bolt ons and a hotcam... 7psi should get you near 400-425hp on stock motor.
Look at some of the turbo L98 builds on this board for more information. Stock block will handle it. Stock rebuild tranny will handle it for alittle while if you dont launch on it at the track with slicks. Should be ok there.


No body does mail order proms for a turbo/boosted car in general. Thats asking for problems. You will have to tune it yourself or find someone who can which may be alot harder to find in Serbia.



Another way is to buy a FMU from a supercharger dealer or someone else who supplies them. Tune it by adjusting fuel pressure rise to add the extra fuel you need. you MAY even beable to use the stock MAF and computer. I think procharger bolt on kits for 5-7 psi on L98s could run well with FMU's only on MAF cars.

Thats probably your best bet...easiest, probably cheapest and will give you the fuel for the hp you need.

Last but not least, with this setup you will need aftermarket ignition box like mallory 685 or similar with timing retard function with boost reference. That is the only way to control the timing with FMU type setup using the MAF based system...unless you setup power enrichment timing advance to pull timing when PE mode is enabled...that requires more tuning gear and if you did that, might as well just do code $59

bduffey723

^^^^^
turbo god

shone190

Uhhh, I see that this is not so easy as I think, and in my country this is not grateful job Here I couldn't find anything stock for this car, not to mention something you said I think that better solution for me and my goal (300HP) is to build NA engine. I just open one thread in TPI section regarding parts I need.
Could anybody tell me what to buy (heads, cam, headers...) to get about 30% power on my L98?

Thank you all very much for the answers.

bduffey723

intake: tpis's miniram
cam: zz409 cam
heads: afr 195's
larger throttle body perhaps a 58mm

that should get u some more power

Orr89RocZ

iTrader: (20)

yeah you are at a disadvantage being overseas. Doing a turbo isnt hard to do, but need to find the parts to do it and really beable to tune well.

Buying pipe and fabbing manfolds/crossovers etc wont be as difficult I imagine but getting the electronics may be. Not sure if Summit ships there but they do have a lot of parts you can use.

If you stick to n/a, i'd upgrade the TPI to large tube runners and big mouth type base. Then throw in a mild cam. That should get you up near 350-375hp on motor.

Full bolt ons themselves can get near 300-320hp on motor which is 250's at the wheels give or take a few.

Just need to know what vendors will ship parts to you and how much that will be. heads, anything aftermarket will be enough to support 350-400hp. Can you find some Vortec truck heads from a Chevy truck? then need the vortec TPI base or a different vortec intake.

giszo

I think Summit will ship there. At least they ship to one of the neighboring countries.

shone190

Summit ship to Serbia, but shipping is too expensible via their couriers Only reasonable option is to buy parts on e-bay or Rockauto. I just need to know exactly what parts and part numbers to search. I do not have money to buy all parts right now, but want to know what I need and to prepare money for the future buying. I bought this car year and a half ago and it was in very bad shape. I put about 6000$ until today, just to bring it back to stock and functional state Everything you could imagine was bad, broken, change... How, I realise that my ECM is bad , but one member from this forum "whitedevilTA" will send me his ECM for free and thanks him a lot. After that I want to save money for build engine and want to know which parts I need to get those famous 300HP
I have some friends which import cars from USA so there are many ways to bring parts to Serbia, but I just need to know exactly what parts to buy

So, I'll need which cam, headers, heads, rollers... to buy, nothing else

Thank You all in advance.

Best regards.

Nenad!

Orr89RocZ

iTrader: (20)

Summit then will sell just about all your needs so you can do a strong n/a setup. I dont know if they sell a FMU but if they do, you could try the turbo swap.

They have good selection of heads now and good selection on cams so you should get what you need to make power.

STILL need to tune with heads/cam/intake swap. MAF makes it easier to do, but still needs some work.

lb9 GTA

It takes more than 7psi to get 400hp out of a stock L98. The 12psi kit from Procharger a freind of mine had only made 320whp (most likely still under 400hp at the crank). I know turbos are more efficiant but not that much. It was done with an FMU and ignition box with the stock prom even at 12psi.

I'm hoping to get just under 400 crank hp out of my lb9 with 14-15psi with a small turbo (rated to 425hp not sure on the size) which is why I started reading theis thread.

BTW the 700R4 is only rated to 340lb/tq and the stock L98 already has 330lb/tq. It won't last long behind one with a turbo

Orr89RocZ

iTrader: (20)

I'd consider 400 hp on motor at around 320-330whp... its pretty close. 10-12 psi on a stock L98 may actually be closer to 400 hp on motor then... from basic turbo math, 7-8 puts you at around 400 on motor if you use some mild bolt ons as well...so real world it may be alittle off.

shone190

I just called my friend who is familliar with USA cars and he told me that have one Vortech V-1 supercharger He had plan to put it into one of his four C4 corvette but he dropped that idea. He will sell V-1 to me for 300 euros (about 370$) because he don't need supercharger at all. Also, he will help me in process of supercharger installation, when I bought all the necessary things for installing.

bduffey723

i wuld do it. especially if he helps u tune it for cheep or better yet free. thats the hard part. or if u pay a pro to tune it its big bucks. gettin a cowl? they're my favorite.