Kitten Tooth

I've never built an engine for more power than stock let along anything with forced induction of any kind... but I've been reading up on Turbos and blow through/draw through setups with carburetors. Heres what I have and what I want to do.

Chevy 350 4 bolt bored out .030 over with ported 883 heads.
Comp 279 Thumpr cam
very stout valve springs
Roller rockers
High volume oil pump with a deeper than stock pan.
Knock sensor and AFR gauge

TURBO SETUP
2 Borg Warner T4 Turbos pulling through 2 Rochester Quadrajets, blowing into an Edlebrock dual quad manifold (or something else, could be a manifold for 2 2bbl carbs).
Hugger headers flipped upside down to feed exhaust side of turbo.
Electronic fuel pump (originally for tbi, I believe it feeds around 15-20 psi?) with a pressure regulator set higher than a mech. pump would feed.
Maybe methanol injection to fix any lean burn issues that might present themselves?

Im making my own plenums for the carbs. Probably gonna fabricate quite a few other things as well..

I discovered the 301 turbo V8 on the internet and thats what turned me onto this build.
What do you guys think?

Kitten Tooth

Drivetrain would be a rebuilt TH350 with a shift kit. 3000rpm stall converter and a ford 9in rear end with a detroit locker

midias

Seems like a mismatched combo.
Those trash thumpr cams usually require RPMs to make any power and 882 heads are not a fan of RPMs. Also I would bet they crack in short order with the added stress and removed material.

I would get a comp cam designed for forced induction and some decent heads to match then move forward

Orr89RocZ

iTrader: (20)

Do a blow thru. Dont draw thru. Its better this way

Get a single pattern cam on a wider lsa than that thumpr

86CamaroDan

way too close of LSA to do anything with boost. You want a 112-114LSA cam vs the 108 you have - Otherwise it will be bleeding off boost out of the exhaust valve.

86CamaroDan

Methanol wont fix any lean burn issues, your also gonna need a boost refrenced fuel pressure regulator, and your carb reworked.

Kitten Tooth

https://www.summitracing.com/parts/n...make/chevrolet
What about this cam?

Also I did some more reading on Methanol injection and yeah i was wrong about the lean burn thing. It just helps with detonation. I found plans on making my own ignition retard setup here
http://www.instructables.com/id/Dirt...harged-engine/

Im just starting off with draw through because it sounds easier. The way I see it it I wont need to change much on either quadrajet since its just getting pulled through like it would if it was mounted on the manifold without a turbo. I have some more reading to do regardless on both draw through and blow through with a carb. I went into this not know jack s*** about camshafts too...

Kitten Tooth

http://www.ebay.com/itm/Borg-Warner-...1W3xCS&vxp=mtr
also how do i know if this turbo has carbon or dynamic seals?

Kitten Tooth

What about vortec heads?

midias

The first cam you posted was a flat tappet cam and this one is a roller cam. What is you engine setup for? I am guessing flat tappet if you have 882 heads. Are you willing to spend the extra for a roller conversion?

They are the best iron head chevy ever made factory so they are a big improvement over 882 heads.

Xter

Don't do a drawthrough setup. First you'll limit yourself to non-intercooled and relying on the gas to cool the charge, second you're going to have a bomb ready to go and lite a fire if you ever have a backfire with all the atomized gasoline in the piping. And you'll probably just ruin the carbs, turbos, piping, and potentially your car if it does backfire.

Buy a holley double pumper and modify it for a Blowthrough, or buy a CSU Carb. Much safer this way.

Or you could get an enclosed carb box and not worry about modifying the carb. It'll just be a PITA to adjust the carb.

86CamaroDan

Much better cam, Usually turbo cams are closer to NA cams in the aspect a slight amount of intake lift is better. Orr or some of the turbo guys might be better suited to suggest a cam as im a blower guy. Im not sure if 112 LSA is suitable for a turbo car honestly.

As far as the roller cam - Its a improvement, but if you dont have a roller block, youll need a set of retrofit lifters, cam button and thrust washer.

Im not too sure i would be doing that. the draw through set ups arnt very reliable as far as i know. I think you would be better off with a blow through carb, or atleast a TBI setup you could tune. I want multi port EFI so i have total control over the fuel right before the intake valve vs dumping it in the middle of the intake.

As far as vortech heads, im happy with mine, and as stated above, their the best cast iron GM head makes - Possibly the best cast iron head even in the aftermarket honestly. none of the imitation suff seems to stack up, or if it does you might as well buy aluminum heads.

Orr89RocZ

iTrader: (20)

If you havent done a modified natural aspirated motor before then you are biting off more than you can chew by thinkin twin turbo

Build and tune up the motor first before goin turbo.

Cam keep it small and on a 112-114 lsa in on a 108-109 icl. Duration in the 212-218 range and same on exhaust side. Hot cam is not a turbo cam. It could run ok but its not optimal

Oem vortecs can be prone to cracking. I would run oem L98 083's

midias

There are camshafts designed for tubos just get one of those far better than using the wrong camshaft. Here are a few examples

https://www.summitracing.com/search/...ibanner=SREPD5

83 Crossfire TA

iTrader: (2)

Turbos don't come with dynamic/carbon seals unless you special order them that way or have them added. It wasn't that common back in the day, and certainly isn't now.

Honestly, these days I have no idea why you would build a draw through setup, but to take that a step further, for the most part I don't understand why you would build a carbed turbo setup, you are leaving so much on the table with a carb and you'll likely be in it for as much $$$ by the time you get it all working right that you would have been better off going with FI. Maybe if you insist on running a carb on a race only setup where you basically just need it to start, run and fun at WOT, but there are just so many things you can adjust for with FI that you can't with a carb, many of which turn up with turbocharging that it just doesn't make sense.

And like other's have said, if you've never done an NA build, then jumping straight into a turbo build is going to be a very steep learning curve. I'd suggest building an NA engine with >9:1 compression and racing that for a season or 2 and then turbocharging it.

There's tons of choices that are better than the hot cam, this is a bit larger than Justin suggests but depending on the power band you're looking for might be perfect, I'd bet that this is the most common cheap cam used in SBC turbo builds:
https://www.summitracing.com/parts/sum-1104

I haven't run into an issue with vortecs but if you're concerned the castings used on the 2500 and bigger trucks are supposed to be more durable. Honestly, for most people you'll force enough air in no matter what heads you use to make a good deal of power, I would just pick based on what you have laying around that's in good shape and has a chamber size that will give you a reasonable compression with the short block that you're using

Kitten Tooth

I need to read the part descriptions alittle closer lol. I mean to run a flat tappet cam, I didnt see that that particular one was roller. Does anyone know of a good article on modifying a carb for blow through? I've found lots of places mentioning it but I don't know what parts of the carb need attention. I know fuel delivery is a big one and the Q-jet kinda fails at having one fuel inlet. I also know that fuel injection is superior and have done ALOT of reading on Rochester 2bbl TBI. Money is certainly an issue or I would just get online and buy one of them Atomic TBI setups instead. Do you just change fuel tables in the ECM for the turbo? Can you change timing in the ECM or is that all just controlled by the ESC and there isn't really any output from the computer? Im starting to realize that draw through is maybe more of a pain than blow through. I just liked the thought of 2 big ugly air filters on either side of the engine lol. Id like to stick with the Quadrajet if i use a carbed setup. If i do fuel injection, its gonna be GM TBI. the common one with the 1 11/16" bores and an ECM out of a Caprice. One last question, Does LSA effect overlap? Overlap is when both valves are open for a split second right? And this bleeds off boost if im not mistaken.

As far as detonation goes i was just going to use methanol and make my own injection setup. An aftermarket knock gauge and when i see knock id just hit a button and run a crap ton of methanol down the intake.

Kitten Tooth

And vortec heads it is.

Kitten Tooth

To be clear, this is going to be a drag car. I ran from the cops last summer and lost my license but THANK GOD they're opening a drag strip not too far away from Sioux City.

Street Lethal

iTrader: (16)

If that is the route you want to take, then go for it. A draw-through can be made to utilize a front mount intercooler, especially if you fabricate the intake intake manifold for your particular application. Plenty of innovating people doing this out there, and plenty of different ways to increase fueling needs for the carb as well as timing control timing. Go for it...

Xter

http://www.hangar18fabrication.com/blowthru.html

There's an article on how to modify for a blow through setup.

GM TBI systems will not support much for an FI application. You're limited right off the bat by the fuel injectors in the TBI systems and you can't upgrade them to inject more fuel. The only TBI systems that will work are the ones are aftermarket like Holley or FI Tech.

Tuning changes depend on what you're using for the ECM.

Honestly I really think you need to research a lot more before delving onto this. Even more so with your methanol idea. I'm not trying to turn you away from this project but you need to seriously sit down and research a lot and look at a lot of build threads before you start this project. I don't want you to blow your engine up due to something stupid or get yourself or someone else hurt.

Now don't let that demotivate you any from doing this. Just do as much reading as you can and start to piece together an idea on paper and get your parts list started.

If you're going to go carb, decide if you want to build a blow through or buy. If you do go with a carb, you're going to have to one huge problem. There's really no great way to control timing. You can ether lock out the timing and run that so you're safe in boost, but cruising and starting the car will leave a lot to be desired. Or you can go with an aftermarket module to control timing/retard timing in boost. Generally from what I've read the latter is a PIA and not really reliable.

If you're going with EFI, you have quite a few choices. I very strongly recommend a Multi-port FI setup. It's really the only way to go IMO with FI setups. You can use GM EFI setups, in fact you can use the stock 7730 ECM from a Camaro and run code $59 for FI. That means basically you can use the stock TPI and wiring harness.

You could also go with a later ECM like a 411 PCM found in 99+ trucks, cars, and vans. You'll have to search to figure out what one is best for you. You'll also have to modify the wiring harness.

Both of those options will need an aftermarket tuning setup. The 7730 can be used wit TunerCat I believe and you'll need an memcal reader/flasher. The 411 ECM you'll need something like HP Tuners or EFI Live to tune.

I didn't see you mention anything about your fuel system. 99% you'll have to make upgrades here to even be able to deliver the fuel needed at WOT. I'd recommend an adjustable boost referenced regulator and you'll need a fuel pump that is able to deliver enough fuel depending on your HP goals. If you're going EFI you'll need injectors that are sized big enough depending on HP goals. You could also have to run new fuel lines big enough to deliver the fuel too. Again depends on your HP goals.

If you want to go turbo, you're also going to need a wastegate, or two wastegates if you want to go twins still. You'll also want a blow off valve. Depending on how much boost you want, you might need an intercooler too. If you're staying at 7 PSI or below, it's not needed but I'd still recommend one depending on your intake air temperatures. Hotter air going into the engine can cause denotation.

If you plan to run methanol I wouldn't just hook it up to a button and spray a crap ton in there. If you insist on building your own methanol kit, size the injector correctly, and put the injector ether pre-turbo or before the throttle body. I would get a hobs switch that would activate at 6 PSI and wire that to the pump, so then when you have 6 PSI of boost, the methanol will automatically start spraying and when you are below 6 PSI, it will not spray. Then I'd just wire a green light into the cabin somewhere so when it comes on, the light will light up and you know it's spraying.

You're going to need a wideband to monitor AFR. Without one, well you're going to blow something up.

You're also going to need to determine what size you'll want for the turbos. Bigger isn't always better. If it's too big you're going to have a spool up that'll last forever. Too small and you're restricting yourself and overheating the compressed air. This will depend on your HP goals. With a 355 SBC, I'd look into a pair of T60 if HP is your goal and you want twins still. If you go with a single turbo setup, then GT45 would probably work well for you but it all depends on your HP goals.

86CamaroDan

Hook the methanol to a hobs switch. By the time you see the light and hit the button, the rods will be hanging out of the block. Also if you build a kit, make sure you get a pump thats capable of over 150 PSI. You want a good spray mist, not a solid stream/trickle. I think your best bet is to just buy a snow performance kit. Their only 360

Kitten Tooth

Okay well ill experiment with a carburetor most likely but now im leaning towards using fuel injection. With tuned port injection, do i just rob the computer out of the car in the junkyard and reprogram the EPROMS? FITECH is kind of pricey for me but i suppose i could save up for a system eventually. i guess my question is how tuned port injection works. Im going to assume theres a mirage of aftermarket injectors of various sizes out there for it. I just need a manifold and all the other goodies that go with it right?

Xter

if you want to use a GM ECM, then get a 7730 ECM out of a Camaro or Firebird. You'll need something like a Moates burner to flash a tune into it. Then just figure out the wiring you need via Austins Third Gen. Using code $59 I can't tell you anything about because I've never messed with it.

If you're using the Caprice like I seen before in your profile, then you'll have to spend some time looking at the body wiring diagrams and ECM diagrams to figure out how you'll need it wired.

There's a lot of different injector sizes. What you need in for these just like your fuel pump will depend on your HP goals.

What are your current HP goals? Will you want more HP later? And what manifold and injector rails do you plan using? All this will factor what size in lb/hr and the height on the injectors.

Kitten Tooth

I would like to see 600hp or more. Im looking into FItech fuel injection now but im not having much luck finding how it supports boost. And at over a grand for the setup it might be out of my budget.... i was looking at the 30001 model. Otherwise im going to buy a tuned port injection manifold and plenum. And find an ECM

Xter

https://m.summitracing.com/parts/fif-30012

That'd be the one you want to be looking at. Handles up to 25 PSI of boost.

600 HP is about the reliable limit for a stock block. They can be pushed farther but you're going to be gambling then on whether it cracks or not.

Kitten Tooth

So the block is the weak link at that point? I figured the crank would go first but from what reading I've done, the stock crank is stronger than alot of the aftermarket ones available. On a side note heres a revised list of what my build is probably going to be. Some of these parts are knock-offs (i know im taking a risk but have done thorough research before selecting these parts)

Forged Wiseco pistons DISHED .030 over http://www.ebay.com/itm/351442671041

Forged 5.7" bushed Eagle H beam rods
http://www.ebay.com/itm/192055269911

Gonna try this cam http://www.ebay.com/itm/112098316173

Wastegate (bear with me if its too big/too small but ill be using a knockoff like this nonetheless) http://www.ebay.com/itm/282128698984

knockoff GT45 turbo www.ebay.com/itm/141784729785

blowoff valve http://www.ebay.com/itm/350610925184

Intercooler http://www.ebay.com/itm/390242163657

And some Vortec heads.

Probably run a Q-jet for fun at first until I save up for the FItech throttle body.

Kitten Tooth

Wouldn't that leave the intercooler full of a compressed fuel air mixture? The mentioning of a backfire induced explosion kinda scared me lol but I suppose my car is going to be equipped with a fire extinguisher somewhere in that gutted interior. And I suppose since the timing would need to be retarded for boost anyways to avoid pinging and detonation, the likelihood of a backfire through the intake would go down some..

Street Lethal

iTrader: (16)

No. During normal engine operation under vacuum only, the fueling is being taken down through that trap door flap built into the intake plenum. Once boost kicks in, the boost forces that trap door closed from underneath, then all air and fueling makes it's way through the turbine, then back into the plenum under the trap doorway. Adding a front mount intercooler not only allows for the air/fuel charge to cool, but it also helps the fuel to atomize. Once you're out of boost pressure and return back to vacuum the engine essentially pulls every last bit of fueling from the intercooler back into the engine. Remember, when the the trap door is open both air/fuel is coming from the carburetor through the plenum, when in boost the air/fuel is coming from the turbine only because it forces the trap door closed. However, even when the trap door is open and the turbo is not being used, air is still being pulled in from the turbo by the engine because the exhaust is still driving the turbo and that air needs to go somewhere. So no, there's nothing trapped in the intercooler when off boost.

Kitten Tooth

Well thats where my build differs I guess. I saw the reed valves in that video and that explains it because at first i didn't understand. My assembly wouldnt have the carb on the manifold. It would have it on an exterior plenum. The turbo would draw through the carb, through the plenum, and than push the fuel/air mixture through the intercooler and then into the manifold. Im sure startups would be difficult and cruise/idle may be rough.. but this is in a car that only sees the drag strip and nothing else. I wanted to do a twin turbo setup. Basically a turbo on each side fed by hooker headers flipped upside down. They would draw through 2 quadrajets and both would feed into an intercooler that had one outlet. That outlet would run right into a 4 bbl manifold. hopefully this poorly drawn illustration explains it better lol

86CamaroDan

so if i understand this correct, you expect fuel to defy gravity and make it into the engine? Your fighting a uphill battle. You got a better chance running a stock TPI and megasquirt, but even that your in it for 1000 bucks not including the fuel system. I'm about 1800 into my fuel system/induction/engine management and i wouldnt feel safe doing it any other way.

Street Lethal

iTrader: (16)

... you can try your illustration out and see how it works for you, but yes, from what I am looking at with your illustration it will affect how the engine idles, how it runs at part throttle, not to mention how it transitions from vacuum to boost, then back to vacuum. The reed valves solve those issues in a tremendous way. As for the raw fueling, remember that fuel vaporizes at 140 degrees, and the temperature of the turbo charger well exceeds that, and the boost pressure forces the air/fuel vapor mixture through the intercooler with no problem whatsoever. This is basically what Smokey Yunick was getting at, to draw raw fuel through the carb with a turbo charger, then force the air and raw fuel through a turbine exceeding 1000 degrees instantaneously causing the raw fuel to vaporize, then forcing the air with fuel vapor into the combustion chamber.

Xter

I just don't think the intercooler with a draw through is going to work well. The reed valve seems to work really good but no idea on cost.

I think the the biggest issue you're going to have is fuel puddling in the intake charge in the intercooler. Too cold and the fuel loses its suspension in the air.

If you want to do a draw through go for it. Just do a lot of research and understand the pros cons and limits.

I think your best bet for a draw through is going to be a single turbo, with your charge pipes sized a little on the small side. That way you can keep the Air temps up a little to keep the fuel vaporized. I'd still be wary of a back fire though with this set up but I guess being you just want WOT and idle, you can do it without an issue. And with that set up, if you want to run Methanol, you should but the meth injector right before the manifold so if it cools the charge enough that the fuel loses its suspension, it just falls into your manifold.

Street Lethal

iTrader: (16)

In this type of setup, I would be more concerned with the critical point of the fuel when in the turbo as opposed to condensation after vaporization during the intake flow. The blades help atomize the fuel, and the temperature of the turbo will immediately vaporize it. To be quite honest though, if puddling is still in the back of your mind, then since this is just a track car only and you're not worried about ambient temperatures during everyday driving, then just scrap the draw-through w/intercooler concept, run the draw-through setup as a hot air setup, but rather than run gasoline, run E85 instead. Problem solved...

Kitten Tooth

http://www.ebay.com/itm/CXRacing-Uni...hS133b&vxp=mtr

Okay so how about a smaller water/air intercooler WAY closer to the intake manifold to cut down on some of that plumbing? Still twin turbo, but with a 2 into 1 at the inlet of the intercooler?

As for backfiring issues, My boss said the boilers in one of our buildings has a brass flapper check valve. If i could find one that around 2.5" and put it inline before the boost pipe runs in the manifold and then a fairly large blowoff valve between the check valve and the manifold, it could be kind of a safe guard, keeping the explosion (should one occur) from going back into the intercooler and then the blast gets blown out the blow off valve. unless that check valve would just be too restrictive..

Kitten Tooth

as for methanol injection, ive planned on having it shot right into the manifold rather than at the intake of the carbs. Id get a proper setup too with a controller and a 1 gal fuel cell.