Me and a friend are putting a twin turbo on my 88 maro and i was wondering if i could do that. it will be run at 3.5-4.5psi each turbo for reliability and driveability.I was told once that you dont blow a stroker(No Jokes) But my friedn says that all your doing is making more power.Also what would my compr. ratio be would it matter with the twin turbos. they woulds both be separately intercooled so intake temp would be cooled. what tranny would i use. Would i buy a newer 4L60E to handle the power cuz im only looking at about 500hp and 600ft/lb at the max. Oh yeah i was planning on adding some mild parts like a performer intake and maybe a 454TBI unit to flow more and other such stuff :confused:

Unless you have very deep pockets and a LOT of fabrication ability you might want to re-think this project. I don't mean to insult you but this undertaking can be VERY involved. Getting an electronic transmission to work with a twin turbo 350 would also be expensive. The rear end and suspension would be a problem as well.

FWIW, to get in the ballpark with the boost you will need, use this formula:

(Desired HP / Original HP) -1 = X percentage

Multiply X percentage by 14.7 and you get the boost you will need. This is a rough estimate, it doesn't take into account intercooler efficiency, intercooler pressure drop, turbo air flow in lbs/min, pressure ratio, turbo sizing and efficiency, etc. And that's just the tip of the iceburg when it comes to variables in a twin turbo system.

As an example, you want 600 hp and you have 375 now (taking into account lower CR, boost specific cam, etc). (600/375)-1 = .6; 14.7 *.6 = just under 9 psi of boost.

Have you selected your turbo/turbos yet? Do you have the compressor map for it?

And yes, you can boost a stroker motor. My 434 was built specifically with boost in mind. Hope this helps.

You may be better off with a 144 or a 177 belt driven supercharger b/c of all the custom fab. work needed on both sides of the plumbing, (intake and exhaust).

TT's are great but like already mentioned are a real pain unless you have experience doing this stuff or a friend that has already been through it and can help you out.. AND deep pockets help, too!!

Anyway, good luck with whatever you decide AND please come back later and keep us up on your progress.

pdq67

I have looked into doing a project similar to this myself. I got into racing and gave up. It could be done for a cheaper if you didn't need it to look professional. I bought a book off ebay by Dick Datsun called 21st Century Turbo. It is a good book for giving you ideas on how to turbo a car on a tight budget. He concentrates on carburated turbos. A build up Turbo 400 transmission would handle the power as well as anything and save on some headache. If you do get into this project there are forums like this one for turbo cars.

I am going to do the same with my '67 Camaro also.
I guess I will spend about $300 for the engine part.
I have a 1978 305ci with a 2bbl. I am keeping the stock 2bbl intake because the turbos will blow the air through the inlet anyway (maybe I'll get an intake of a 4bll to make it smoother). I bought 4 carbs from a turbo'ed car ($20 each), these 4 carbs will be big enough to deliver fuel for a 350ci engine. I will weld 2 boxes, one for the connection between the bottom of the 4 carbs and the intake, and the other box for the connexion between the top of the carbs and the turbos.
I am using turbos suitable for diesel-engines because these are very easy to find on small trucks, vans, etc. and they give boost in the low rpm range because diesels cannot handle high rpm. Also my 305 is a long stroke (?) engine, so this one also is not a high-rev engine.
These turbos I need must come from a 250ci? diesel (2.5 - 3 liter) and must be 'oldfashioned', so no electronics involved in the boost setting, just an external wastegate, nothing more.
I guess these turbos should cost about $75, second-hand ofcourse.
I will rotate my stock headers so the flange of the headers will point to the front of the car. I will bolt the 2 turbos onto these flanges (by means of other home-made flanges) and I will have to remove the fan and install an electrical fan. From the turbos I will use silicone hoses (or steel) to the inlet of the carbs. I will measure the pressure just after the 2 turbos and just after (or before) the carbs.

This setup will be cheap, will look like a war-zone, will be b*tt-ugly, will be no show engine, but it will run like a panther!!
And if it doesn't run, I just put the carb back on! :D

Turbos aren't that complicated (for carb engines) the only problem is when you exceed your engines boost limit... :D but put a dump-valve in the system, and no problemo.
I will not run that much boost as I don't know if my 10 bolt and th350 will hold it...

Me and some friends have experience in turbo cars, so we know what to do. If you do not have any experience BUY BOOKS and READ so you get the basic knowledge of turbos.

And to keep everything simple and easy, stay with carbs, no computer controlled injection, or other sh*t. If you use carbs, it will be rather cheap to get the power you want, if you use computers, you will need lots of money and time.... no fun!

Goodluck with your project!

DL, what compression ratio do you have and what octane gas do you run? It appears that you don't plan on running an intercooler.

69ProTouring, My engine has 8.4:1 CR, and I am running 98 (premium?)
I am not yet planning to run an intercooling because this will be an engine to play with. I have an intercooler laying around here, but I will only use small boost, so the intercooler will not have that much effect as I don't use all the hp.
I will use this stock engine to make about 250-300hp. If the turbos and the carbs run great together, I will remove everything and put it onto another engine (350, 383?) which I have to build to withstand much more horses and torque than the 305ci.
The biggest problem I have now is that my engine is a low rev engine.... If I could only have the original 283ci in it :D

My goal is to make somesort of low-budget 'bolt-on' horsepower/torque. I don't know howmuch hp/tq my engine can handle, but I will start with low boost, and increase it until I am happy with the result and when no strange noises appear in the engine :D . If it blows it blows, but this is a better purpose then using the 305ci as a boat-anchor :D ;) .

Yep that's the way it is done! At least according to what I have read. Don't buy turbos that are too big, small ones will spool up faster. Two different turbos can be a good thing, one will pick up where the other runs out of breath. LOTS of carburation. As long as you don't go over 15 psi you shouldn't need a carb box.

As for the gas i plan on running on 94 octane or at least 93. The comp. ratio is gonna be dictated by the stroke i will end up using. it will be slightly longer than stock. I have a friend that does nothing but work on race cars and turbo cars (talons, eclipses, and CRXs). the turbos are small about the same as a stock tubo off a talon or eclipse. The turbo manifolds are gonna be the hardest thing to find. My wife wants a TT 454 for herself but she wants it shoehorned into her firebird. That wont happen til i get mine done. The rearend will probably get changed out to a ford 9" from what i heard these are strong enuff to handle the torque. The tranny however might have to be rebuilt at least, i might go for a new one but i plan on doing highway driving so i will either need a low(numerically) rear gear or an overdrive or just a low last gear like .62 or lower to keep the revs low. I would like to get a turbo book from summit unless someone would recommend a better one. anyone wanna email me im at IndyDusBriver@aol.com graemlins/waving.gif

by the way pressure or boost will not be over 9 lbs. to keep from having to go all out and not blow a piston through the pan.also i have a lead on using 2 intercoolers from 2 turbo talons and they are very efficient. they may be 4" thick but they are only about one and a quarterfoot square so i can mount them with only a smallopening to feed them.Oh yeah i would use diesel turbos but i prbably wont have enuff backpressure to keep them spooled up.The original TBI will be replaceds by a 454 unit my friend is looking for while he works on his cars. thanks for the advice and i will keep everyone posted as well as post my coming soon website when my page is finished as it will cover my buildup. later

don't bother using the TBI crap, I know someone who fabbed up a paxton centrifugal blower kit on his 92 TBI 5.0 'bird, he says it's not worth it

as for stroking and power adders --------- HELL YES!

I would recommend a 355 and the twins
try contacting charged air systems for some tech info (two MFBA members were prototypes for Tony's twin kits, one LS1 and the other LT1)
there is a twin turbo 355 LT1 4th gen in the new gm high tech perf magazine . . . 112 mph in the 1/8th

keep the compression as low as possible . . . 8 - 9 to 1 tops
forged internals and a strong fuel system
a blow through carb will work but I think if you're going this far make the switch to EFI or at least a TPI setup
the tuning makes ALL the difference . . . power, drivability, reliability

one last thing
the 700/4l60/4l60E (you need a controller for the E remember) would be a decent choice, but you're gonna need a well built one to handle the torque a turbo is capable of
then again any trans will need that lol

myblu88maro, the eclipse uses the "small" garrett TB2566 turbo. (Ballbearing T25 turbos, I have been told that the lower the number next to the TB25 (here 66) the faster it speeds-up)These turbos are also very often used on diesel applications. I don't know the availability and price of gasoline turbos in the US, but here in the Netherlands the Diesel turbos are cheaper and more easier to find.
You can find a complete cataloge of turbos (Garrett, Mitsu, etc.) and their different applications on many many cars on
http://www.turbomaster.com/catalogo.asp or http://www.turboshoet.nl/ then just select "turbo's" and search the car-brands which are easy to find in the US.
If you are still searching turbos, both these lists can help you selecting car-models which have the type of turbos you need (new or second hand).
If you have to buy (new or second-hand) turbos from a Porsche you will spend more money then the exact same turbos originally fitted on a "non-performance brand". It all depends how much rpm your engine will do with the TT, but if yousee low rpm, I would keep the xx in the low numbers (T25xx) so it will spool early. Oh, also try to get 2 same turbos (TB2550 and TB2550, not TB2520 and TB2566) it will make things more stable and easier to tune!

Goodluck, and show us pics in the end or during your project graemlins/beers.gif

yeah i will be using the same type of turbos. my friend said id be stupid to do it that way. also the tranny and rearend are gonna be replaced or just rebuilt. i heard of some guy using his 700r4 with around 400-425 ftlbs of torque but that may have been a one time deal. any idea how much torque the 700r4 is capable of handling stock and what it will handle when rebuilt a lil bit stronger??? will i be better off going for a ford 3 or 4 speed or is there a tranny thats is a better choice that is a chevy. also do those gearvendors overdrive tranny things really work

is this a 305 you're talking about?how many miles?also do you have a camcorder? smile.gif if this is the original motor,my duess is that you'll grenade it pretty quickly.as for the 700r4,given a good performance rebuild it should handle 400 horses just fine,although 450 might shorten its lifespan considerably.not sure where greenwood is in indiana but iknow a guy here in columbus that is really good with r4's and is very reasonable on his rates!he honored a warranty repair for me and even peid for the tow!although i'm pretty sure he wouldnt do that from indy!he did my tranny with a corvette servo,a pioneer shift kit,all new internals,and a new stock lock up converter(along with a vaccum modulated shift conversion that i supplied)for under $850!that was a year ago but he still beat all others by half their quotes.
if tou remove the computer,which i'm sure you'll have to,you'll need the vaccum shift kit.i got mine at jegs for around $70 but for more there were some that let you control lockup rpm.
there are several different r4's so be sure the one you have is a good one.any good tranny shop can tell you(if you believe them!).email me at bgn4chng@hotmail.com if you want this guy's info.it's worth giving him a call.
now about the rear end in that car.............!
as always;Good Luck!
Eric

is this a 305 you're talking about?how many miles?also do you have a camcorder? if this is the original motor,my duess is that you'll grenade it pretty quickly.as for the 700r4,given a good performance rebuild it should handle 400 horses just fine,although 450 might shorten its lifespan considerably.not sure where greenwood is in indiana but iknow a guy here in columbus that is really good with r4's and is very reasonable on his rates!he honored a warranty repair for me and even peid for the tow!although i'm pretty sure he wouldnt do that from indy!he did my tranny with a corvette servo,a pioneer shift kit,all new internals,and a new stock lock up converter(along with a vaccum modulated shift conversion that i supplied)for under $850!that was a year ago but he still beat all others by half their quotes.
if tou remove the computer,which i'm sure you'll have to,you'll need the vaccum shift kit.i got mine at jegs for around $70 but for more there were some that let you control lockup rpm.
there are several different r4's so be sure the one you have is a good one.any good tranny shop can tell you(if you believe them!).email me at bgn4chng@hotmail.com if you want this guy's info.it's worth giving him a call.
now about the rear end in that car.............!
as always;Good Luck!
Eric

oops!sorry for the double! redface.gif