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Twin Turbo SBC build, need help

37K views 28 replies 18 participants last post by  mookandairin 
#1 ·
Ok, I did a search, and found some help, but I'm still in need of some answers.

Looking to build a motor top put down ~850-1000rwhp in a 78' Vette.

Anyone know of a manufacturer of turbo manifolds or headers for Vettes?

What kind of turbos would I be looking at for the numbers I am looking for?

It's going to be a 350ci motor, need some help on the rotating assembly, going forged everything, probably ~9:1, sound good?

As far as heads go would like to use a set of GM Fast Burns with some serious work done to them, will these work well?

I'm nearly lost on blow-through set up carbs and what not, some schooling in that department would be great.

I'm familiar with all turbo components, wastegates, bov's intercoolers, all plumbing, and can work all of that out, just need some help on what works well on small blocks.

Does anyone sell a kit for this type of thing?

Any help would be greatly appreciated.

THanks
Dan
 
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#4 ·
I would go with dual T3/T4 hybrids, and your compression is way high if you want 1,000 horse- more like 7.5:1 is ideal. It is possible to run blow through carbs, but I wouldn't do it on this setup, not in a million years. I would go with a MegaSquirt II system. They offer great tuneablitiy, are fairly simple to use and are the cheapest, even if you buy it fully assembled instead of doing it yourself. You'll probably also need to get a custom cam ground, I don't know what RPM ranger you're looking at, but remember to include atleast another 10 degrees duration on your exhaust and a pretty wide LSA (115ish). I guess that should get you started.
 
#6 ·
It is probably possible with the setup you are looking at, but you will have to run race fuel. I was looking into putting a 101mm turbo on a 358 that I have with an air to water intercooler, 9:1 compression and 25-30psi boost. The company that was helping me with it said that it would produce around 1500hp at the crank. That is with 118 octane fuel though. In the end it looked like it was going to be too expensive (around $11,000 for turbo fuel injection intercooler and all the other parts), so I just stuck with the setup that I already had.

Adam
 
#8 ·
I would go for a Dart block, the one you have may hold...but that's a big risk. If you're racing it though I'd go for a 327 with a light rotating assembly and spin it to the moon- its a lot easier to get hp with high revs rather than down low- especailly with forced induction.
 
#9 · (Edited)
Your goals are not undoable, but I hope you have planned to spend some money. As mentioned you will need aftermarket everything in the bottome end. The fastburn heads are not bad, but I would look at a big port race head like a Dart, AFR or something like that. They dont cost much more and will flow alot more air. When you are talking about making that kind of power you have to have good heads even with the turbos.

As for the turbos a pair of T3/T4 hybreds will not do **** for your goals. You need a set of large T4's and that is still pretty small for 1000HP. I would be looking into going with a large single turbo in the high 70's to low 90's on the compressor inducer. You will want a large frame turbo like a big garret from a diesel application. They will move alot of air and are very comfortable making high boost. If you are not going to do a BUNCH of research, you would be better going to a turbo shop and getting something they have put together that will work for your power goals. There are a couple that sell on ebay that have some nice turbos for decent prices from time to time. If you go to somone like turbonetics you can plan to spend close to 3k for a turbo like that, but there others putting together turbos from rebuilt oe parts that are just as good and 1/3 the cost.

You will want to fuel inject an engine like that. Blow through turbo at that level is just asking for a big boom. It will take high boost to make that power on a small cube small block and EFI is the ONLY way to control an engine like that.

You will not find a company that makes a manifold or headers for that application. You will need heavy gauge steel or stainless steel headers. Stainless is the best, but on a budget mild steel will work at low boost. But, with your power level stainless is almost a must. While velocity is important, it is relative. Typically you keep tubes smaller on a turbo engine, but at that power level 1.75" is probably what you want to plan for. For stainless it will probably cost you 2k to get someone to build them, so consider doing it yourself.

And the lower the CR the better. 7.5 is fine. Lower would be better, but it would be hard to maintain quench and get the engine to run off boost.
 
#10 ·
Money isn't much of a factor here, well it is but doing a budget 1000hp car is not a good idea in my opinion. T4's were one of my ideas, I just didn't know if they were too big or not.

Don't worry, will be doing tons of research before I even think about buying parts or swinging a wrench.

Help me out with a cost analysis guys, how far off am I here?

Rotating assembly: ~3000
Headers: ~2000
Turbo(s):~2500
Wastegate(s):~600
Exhaust:~800
Intercooler and Plumbing~1800
BOVs~300
EFI setup~2300
Cam~300
Guages~240

It is 3:30 am right now so Im probably missing a lot, and then of course misc. stuff that will add up, but I'm just trying to get a close number to work with.

Thanks
Dan
 
#11 ·
Some $'s look off like the cam {look more like $600-$800 for the setup, ie cam, lifters, push rods, rockers, stud girdle} and $2k for headers seems high? But when you have your total multiply it by 1.50 {150%} to get the amount it will take to accomplish your goals.

I would look at building a 7.5-8:1 450 hp combo then use a turbo setup that will yeild about 25psi max boost {but you may only need 20}.
I would plan on using something besides a zz4 unless you plan to mud it and run little or no coolant.
 
#14 ·
That banks kit will not even touch 1000HP. Turbos are too small to start and they have those crappy manifolds. I am sure kevin has built a few turbo cars so might as well listen to him on the carb and price thing. My experience and research has been that EFI is BY FAR THE BEST at high power levels. No one said that carb would not work, but for almost 3HP/cid you cant just slap a carb shop holley on it and expect all to go well. You will need a good wideband and datalog equipment just to tune it. Since you can get all that stuff with an EFI setup the price is about the same for EFI as it is for a good carb and all the needed equipment. Not to mention you can tune it from the drivers seat going down the road or in between runs in a drive way. I do all my tuning at the kitchen table from datalog information. All it takes is the data and a little math to correct problems.

You are way low on the rotating assembly if you get an aftermarket block. I would up that 1k at least. You also forgot heads which will run you around 1k at a minimum if you get a good deal. The turbo you could spend alot less if you do some research and look around. I spent $175 on mine on ebay. It is good for close to 1kHP. I also got my wastegate and bov from ebay for pretty cheap. Matter of fact, crank, pistons, rods, heads, efi, injectors, radiator, and other stuff I am forgetting came from ebay. I did my engine on a budget and probably have $7500 in a stock block engine, but it has good EFI equipment and good heads. However, I am looking to upgrade soon after a recent screw up that hurt a couple cylinder walls. I am going to run the stock one till it gives up or till I have the $ for the aftermarket setup.
 
#15 ·
Not that I disagree with you but the company website disagrees. They state "in excess of 1000HP" concerning the 366" engine they sell. They even have a graph showing over 1100hp. It is worth noting that that state 100 octane fuel and an intercooler was needed to make that much power. With their reputation at stake I don't think they'd make false claims and place false ads.

With that said, I agree that it's easier with larger turbos, more boost, less compression and a big intercooler. However, I don't care how easy a turbo is on the rotating assembly, a stock 1st generation block will not handle that much pressure long enough to enjoy it. I doubt it'd last long enough to tune it for that much power.

We're talking about rear wheel horsepower right?

1200-1400hp at the flywheel would get you over 1000 at the wheels. It's a very different ball game when it's in the car. Yes, I agree the Banks kit won't touch that.

Larry
 
#16 ·
Let's look at a couple of things that might make this somewhat impractical.

First of all the drivetrain. Even with 500 HP to the wheels in a Vette your going to tear up the rear and half shafts. 1000HP to the wheels, which puts you in the 8 flat 1/4 area at over 160 by the way, will destroy all things connected from the frame to the ground.

Second, just setting a body on the frame of a Vette will flex it considerably, having done and doing restos on these. A 12 point would be manditory for track purposes and manditory just to keep the car from twisting and breaking in two.

Third, I don't think 1000 HP to the wheels in the same breath as ZZ block nor Fast Burn heads. I think Dart block and heads that will flow 330+ on the intake and 250-260+ on the exhaust. With very thick deck and o ringed.

With a project like this you'll be crappin $1000 bills. I'd suggest setting aside around 30 to 35 of them to build the car correctly.
 
#18 ·
Actually the kit says 5-800HP from what I saw on the link. The complete engine says that it will handle 1100HP or something like that, but I just dont see it making that much. I have never seen or heard of a banks engine making anything even close to 1000HP, but then again, I have never heard of anyone buying one either so who knows. I am just not a big banks fan. I think that they are severely overpriced for the power output.

I totally agree on the stock block for that much power. Hell, I figure mine is a ticking time bomb at 700HP potential(if I ever get it setup right). I also think that some big Dart heads are a good choice as well. That is why I bought mine. They flow enough for 550-600HP NA so under boost the sky is the limit.
 
#19 ·
Yea, I saw Banks on horsepower TV and wasnt a fan of his setups, just didn't like the way he was doing things.

Anyways, twin turbos may not be the route to go with this car. It's my friend I'm asking for, and he's going to be putting a C4 style rear chassis and what not in there, so it will be able to hold up to alot of power, but maybe not what twin turbos will give, the initial plan was a wild nitrous motor, and then we started talking turbos and how much potential they have, because I used to have a talon and those things can make some insane power with a turbo for a 4cyl.

Looks like nitrous might be the way to go, his heads would be perfect for a nitrous motor, just need a new cam and bottom end and it would be set for spray.

Thanks guys
 
#21 ·
if your lokking into twin turbos www.wrenchrat.com makes good set up's for blow through carb set up's. i personally love the header design! If your looking for a cam look into comp at the nos and turbo grinds. most lower ends won't hold that type of power, but scat makes some good forged cranks. me personally i have my dad getting mine made from some one in wisconson, its the same one that is in his sprint boat. rods go with h-beam but not EAGLE! I used them when i turbo'd my accord and bent one and a week later one blew a nice hole in the block. so manley was a better choice. Dart or APR would be a good way to go. compression ratio between 7.5 or 8.5 would be better then the 9.5 remember this isn't a honda. i would look into a dry sump setup with the turbo's as well. t4 is kind of small i would look into garrett gt42r-gt60.
 
#22 ·
twin turbo

if your lokking into twin turbos www.wrenchrat.com makes good set up's for blow through carb set up's. i personally love the header design! If your looking for a cam look into comp at the nos and turbo grinds. most lower ends won't hold that type of power, but scat makes some good forged cranks. me personally i have my dad getting mine made from some one in wisconson, its the same one that is in his sprint boat. rods go with h-beam but not EAGLE! I used them when i turbo'd my accord and bent one and a week later one blew a nice hole in the block. so manley was a better choice. Dart or APR would be a good way to go. compression ratio between 7.5 or 8.5 would be better then the 9.5 remember this isn't a honda. i would look into a dry sump setup with the turbo's as well. t4 is kind of small i would look into garrett gt42r-gt60.
 
#23 ·
you must drop the compression if running a carb on this setup. Get some gigantic injectors and build it well and it should be okay on 9:1. Intercooler, water/meth inj, timing, and tuning tuning tuning. The carb I don't think will get you there without a few surprises.

... my question is why aren't you just buying an lsx so you don't have any doubts or headaches or waste 10,000$. Seems like you have the money to me.
 
#24 ·
banks kit for less HP goal??

i am looking to do a sbc twin turbo kit... im not looking for crazy numbers i just want something "different" under the hood...my z28 is my daily driver so i want something that is going to last... manifold design i could care less about... i just want 500-700 RELIABLE HP...

here is my set up so far
dart shp block (383 ci)
speed o motive balanced & forged rotating assembly
AFR race heads (fully machined) 72 cc chamber 8.5-1 comp ratio
1.6 rockerarms
no intake or carb but im thinking 2000-5500 rpm range so edelbrock rpm intake
750 blow thru carb (didnt buy it but ik i need one)
undecided on cam
gear driven timing set

i dont want to build something some one has done over and over again IE a blower sticking out of the hood

basically i just want a no complication bolt on twin turbo kit
the banks kit and wrenchrat kit are about the same price and seem to be quality kits

my question is would they be good kits for my goal or should i make my own kit????
 
#25 · (Edited)
Depending on your build skills you can build your own kit for less money. However, picking the right components and making it work together takes time and research...ALOT of it. I have done a couple of these one off's and they are tons of work. I would suggest getting a kit if you have deep pockets, dont have alot of time, alot of patience, and good fabrication skills. I can help with some build specs, but in the end you will have to do your own research to have any level of success tuning it and keeping it together.
 
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