vortec350s10

So I'm getting kinda bored with my car, as I don't think I can do much more tweaking. I've got it about as good as I can get it with the current setup. So, it's time to add power. I could spend 1500 on new heads and cam, gain 50 hp maybe, but that does not sound that exciting for the money, so I have decided that it's turbo time. This is a weekend street car, although I do drag race a couple times a month. 600 crank hp I think would be a good optimistic goal.
Ok so here's my plan, let me know what you guys think

GM 350 HO crate engine- current comp ratio is 9.1
gonna get a turbo optimized cam, no idea on size
gonna swap cast pistons for forged, std bore (4.000)
keeping stock vortec heads
keeping performer rpm intake
have a 650 demon vac sec now- switch to mech sec? I wanna do a blow through carb, guessing vac secs will no longer be functional
redo fuel system from mech pump to electric with return style regulator
would like to incorporate a timing boost retard somehow to keep timing advanced like normal until boost comes in

So for the turbo parts: I've decided on doing a single turbo, and running an intercooler with minimal metal cutting and modifying. I'm planning on making my own headers out of weld elbows and thick walled iron pipe. I've already got 3/8 steel to make the flanges. I'm thinking of running the crossover pipe from the drivers side header between the front of the engine and radiator to join in the turbo flange.

What do you guys think? Suggestions?

Orr89RocZ

iTrader: (20)

Sounds good to me.

Definately get a blow thru type carb to work with this setup. Upgrade to forged pistons with a big dish to get compression down in the mid lower 8's to 1 if you can.

Cam can be a mild 218 deg type cam ona 112-114 lsa. Should work well enough.

Turbo routing sounds good. Can relocate battery to trunk to gain some space up in the engine bay... can have turbo sucking in cold air from thebattery box, and downpipe routing back behind the heater box/firewall or between the number 6 and 8 cylinders like I do onmy manifolds. Designed right, you can easily fit 3" downpipe thru there.

T76 turbo sounds good here for 600 hp. Maybeable to do that with a T70-ish turbo but a T76 fit comfortably with that range.


Ignition box with boost reference to pull a degree of timing per pound of boost will be necessary. Fairly easy to do.

Convert to TPI style electric fuel pump in tank with possible hotwire kit and boostapump kit. Gives higher voltage to get more fuel flow. 600hp is doable on a single pump. 600whp may not but crank hp it should do it.

trbo355

Listen to him because he's fast! A good cam that performs well is the Comp Cams 268h or the summit cheapo 224 dur. .465 lift cam. Use 1.6 rockers with either cam and you can go 9's with either one. Im not a huge fan of boost timing controllers but take a different route instead. If you stick with a vacuum advance distributor, set the initial timing at 15 degrees initial and recurve it with only 10-12 degrees mechanical. Give it around 20 degrees in the vacuum can.

That makes 25-27 total under boost with 45 total at cruise for good mileage and cooler water temps. You can adjust full boost WOT timing up or down a fair amount while keeping initial timing in a good zone. You have to use a simple one way check valve teed into the vac hose and restrict the feed fitting down to a .040 or so orifice so the check valve doesnt get overwhelmed dumping boost pressure.

Its so painfully simple and reliable plus it saves the money NOT spent on a controller. Plus i hate trusting electronic objects with my motors life or death. Im surpriseed more people dont use this foolproof method. Plus at higher boost levels, the resolution of the boost retard **** SUCKS and you have no idea of actual timing under boost.

Orr89RocZ

iTrader: (20)

you been faster than me for less I'd trust your input

vortec350s10

Thanks guys for the input. Orr89, I've read a lot of your build threads and I gotta say they are great, I've learned a lot from them. Yeah since I'm just in the planning phase, obviously I don't have a lot figured out exactly, so I appreciate then tips. I'll have to look in to the fuel pump setup you mentioned, I still have my old tpi pump around somewhere. I'm guessing for a blow-through setup, you gotta run a mechanical secondary carb, right? My current cam is a comp XE 268 but I'm pretty sure I'm gonna want something with a wider lsa and maybe less duration. I'm building myself a stronger 700r4 right now, but I won't really be getting deep into the build til this spring when I get my car outta storage, but I wouldn't mind accumulating some parts that I know I'll need. Also, has anyone ever thought of rigging up a mechanical boost retard mechanism, by converting the vacuum advance over to a boost retard using a tiny air cylinder and return spring? Might be cool. Maybe someday I can play around with the idea.

Orr89RocZ

iTrader: (20)

I'm not too familar with carb systems but definately need to get a boost compatible blow through carb from a good vendor, like CSU, C&S, or the carb shop...etc Good carb makes all the difference. I dont know if they are mechanical or not however.

Fuel system will be under less pressure so maybe a single pump can handle all the hp. May beable to rig up a different fuel system for the carb like an external pump or something. Thats something you will need to look into more.

Keep the cam on a wider LSA.. 112 minimum is generally used for a turbo..some go wide as 116. 112-114 should be plenty. 268 isnt a bad cam. They have been used with success.

junkcltr

iTrader: (1)

Yes, mechanical secondaries. DP650 is a good choice.
Check probuilt transmissions for a 700R4 kit
I wouldn't do that funky dizzy stuff. Just pull the mechanical advance and weld up the slots somewhat to limit mechanical advance. Let the vac can do the cruise advance. Once under boost only the mechanical advance is limiting and it works out great.
I like the 218/218 @ .050, 110 LSA cams I run. Don't worry about the LSA too much. Look at the overlap. That XE 268 is kind of high for overlap using a turbo cam, but isn't horrible. 227 - 220 = 7* overlap. My cam is 218 - 220 = -2*. It all depends on what kind of turbo setup you build. Free flowing exh and turbine likes more overlap............just like NA.

vortec350s10

That's a good point about just limiting the mechanical advance. The simpler the better. A rebuild kit from Dana is what I'm getting. It makes sense with timing, since basically whenever you are over 3k rpm your generally making boost if you're on the throttle, and if you're just cruising maybe your making vacuum. That is something I've wondered- when just cruising, say at 2k rpm, do most turbo engines still pull vacuum like a NA engine? Or it is less vacuum since the turbo is always moving some air? Maybe I'll stick with my current cam and try it. Changing cams for a slight improvement maybe isn't worth it. I'll be spending more money than I think I will as it is. Since it's not a race car, slightly less than optimum setup would still be way ahead than it is now being NA. Anywhere I can save a little money is good

Orr89RocZ

iTrader: (20)

Depends on the turbo size and how much throttle you are giving it, you wont see boost until higher rpm and higher loads.
While cruising at 2000 rpm, you should still see vacuum at part throttle. heavy part throttle you can sometimes see 0 vacuum since the turbo is almost spooled up and creating boost but not quite there yet. Its almost like you had a natural aspirated engine at WOT except your running at only half throttle.

Engine should act like a normal motor with the turbo at most part throttle situations if its sized right. A undersized turbo with smaller turbine may start making boost going up hill at 2300 rpm with a tight converter...but if sized right motor should see vacuum.

More vacuum light load situations run more timing. Just need a way to eliminate that timing as vacuum disappears with heavy throttle. Limiting the mechanical advance sounds like a plan.

vortec350s10

Yeah I agree with simply limiting the mech advance. Makes total sense.

I'm still not completely set on how I'm getting the driver side exhaust over to the passenger side front where the turbo will sit. Once I get a mini starter in there and remove my passenger header I'll be able to see how tight it really is. Sorry my questions jump around since I've got so many different things I'm wondering. I'm trying to at least get a handle on most aspects of this build before I start so I can plan everything accordingly. There's definitely a lot that needs to be changed and fabbed! I don't think I'll be bored for a LONG time once I get started on this thing. I appreciate your guy's input, it's always great to learn from people that have gone through this already, makes it a hell of a lot easier for me!

I just remembered- I still got my original crate engine cam which is if remember off the top of my head: 212/222 @.050 with a 112.5 LSA. I know the exhaust duration is normally LESS than intake for a turbo cam but wouldn't it still be better than my XE 268 which is 224/230 @.050 with a 110 LSA? Both are flat tappet cams.

Orr89RocZ

iTrader: (20)

I'd probably try the 268 over the 212 cam there but the 212 has alot less overlap than the 268. The 212 is closer to a stock type cam spec and most work fairly well with mild boost combos so it may be a toss up here. I know of one guy running a big cammed 385 turbo motor thats on a 108 lsa...so it has some overlap and it ran low 9's in a heavy truck...seems to do well.

Crossover pipe i'd use 2.5" and snake it around in front of the oil pan and up between the a-arm/kmember and the pan into the passenger side header somewhere. Downpipe should go back between a-arm and starter past the firewall and #8 cylinder or between the #6 and 8 cylinders by the starter then down stock exhaust location.

There is a bit of room to get creative there but you will sacrifice some ability to get at the spark plugs and such

Tobias05

referring to the timing, I'd love to run 15* or less mechanical advance on my 350HO. add the difference to initial timing.

with that xe268, have you considered locking it out?

vortec350s10

Yeah spark plug access! That will be interesting I'm sure. My current setup seems to tolerate a real aggressive timing curve. I'm running about 14 initial all in by 2400 maxing at 34 total mech advance. My vacuum canister is cranked up all the way for the most advance. Still won't detonate even running lean and with 89 octane. Lugging it at half throttle with tc locked

Tobias05

unknown_host has a thread where he picked up 2 mph in his 350HO going from 34 to 36 degrees total timing.

vortec350s10

Well I know 2 degree of advance doesn't do that to mine. If seems most people run less timing with vortecs than the older iron heads. Since the combustion process happens a little quicker with the better swirling of the vortecs supposedly they don't need as much of a "head start" to reach maximum cylinder pressure at the right time. I know putting in the longer correct reach plugs helped mine out a little.

vortec350s10

So I got a hot deal on an Aeromotive A1000 fuel pump. Actually, two of them. They were used in a test lab at my friend's work so they got a lot of hours on them but supposedly they both work, so I could use one and have a spare. Anyone have much experience with these? I'm looking at getting a Aeromotive 13204 regulator and running 1/2" (-8) feed and return lines. Also, what type of line are you guys running from the tank to the regulator? Hard or braided?

noboostnogo

iTrader: (4)

A1000s are good pumps, i would get a 13202 regulator. I replaced my lines with -8 feed/return both stainless steel braided, its more flexible and easier to install

vortec350s10

The more I researched, the more I am thinking the A1000 pump is overkill for 500-600hp. I still have some time to think about it, but maybe a Walbro 255 (or two) would be an easier and more fitting choice, since I really don't want to sump my fuel tank.

Well my next question relates to the rotating assembly. I'm not sure if I want to go ahead and swap the crank and rods, or keep them and swap only pistons. My current crankshaft is cast, but I have heard and read that they can be fine in a lot of cases up to 600hp or so. I don't want to skimp though and have to do it later if I wreck something. What do you guys think? Experiences? Do you know of anyone who wrecked a stock bottom end with boost?

calebzman

iTrader: (3)

Adding a forged crank and rods will increase the initial cost, but will probably be a good investment. I would get the entire bottom end balanced once all the new parts are installed.

Here is a pic of how I routed my hot side tubing. It's 2-1/2" and dips down in front to clear the fan motor. I have more pics if you want.

Orr89RocZ

iTrader: (20)

Yes I know a guy who blew a L98 vette motor under 12 psi froma procharger but I think it wasnt tuned properly. It just used a basic FMU and I think an MSD timing retard box. It had a good bit of compression to begin with so it may have been on the ragged edge for pump gas. Ran strong tho.

It wasnt the crank that failed tho...it was pistons and rods...but I think the piston first.

always tinkerin

iTrader: (1)

Are you thinking of doing something like this?

vortec350s10

At first I was thinking that was my only option but now after a few people showed me their setups that run the pipe under the oil pan and then back up by the starter, I'm thinking I'll try that route. It'd be nice to retain my drivers side header too.

Orr89RocZ

iTrader: (20)

If you did the AC delete box and trimmed it back some, and designed the manifold right, you could fit a 2.5" cross over up under the pan past the starter to join into the turbo.

The downpipe then will have to run between the firewall by the ac delete box and number 8 cylinder.

This is basically identical to BBS designs header. However, i'd try to join the crossover into the T4 flange, and not bring it back into the log manifold like BBS does. If I ever get a chance, I'm gonna design a budget fabricated log setup for a single turbo that will fit nicely in our cars...i just need another thirdgen engine bay to work with.

I dont like my twin turbo setup that much, and plan to redo it someday, so maybe I will have time to also fab a log setup.

vortec350s10

"Need another third gen engine bay to work with"- too bad we live on opposite sides of the country, eh? Yeah if you made a batch of single turbo manifolds I would think they would sell like hot cakes, whatever a hot cake is.
My heater box is already modified and is probably similar in size to a non-a/c box. I hope I won't have to flatten it out more since I hate working with fiberglass and bondo. But if I gotta do it, I will.

I've got a few parts accumulated so far, like a carb, mini starter, fuel pressure gauge and I made a 3/8" mild steel flange for the passenger side manifold/header. My main concerns now are what route I want to take for a fuel pump, type of lines, and rotating assembly. I'm awaiting a pro street elite rebuild kit from Dana for my "new" 700r4 I'm building. I wonder what I could get for my current TCI Streetfighter 700r4. $500? Maybe I'll have to start a build thread once I really get rolling on this whole project. I'm making sure to take pictures!

83 Crossfire TA

iTrader: (2)

I'd love to know how you're imagining this working, would you still try to run the crossover in the stock location like the BBS setup? I've run this back and forth in my head and looked at a car more times than I can count and I'm not sure that the best answer is. If you run it through the stock location, up and then forward to the flange, then basically you need 2x 2.25" or so pipes running forward in that area (the manifold and the crossover), a 3.5 or 4" pipe running back (downpipe) and one or 2x 1.5-2" pipes for the wastegate. There is barely room to do it but I don't see how without making the car a serious bear to service.

running the crossover around the front of the engine is OK for a dedicated racecar, but presents a lot of compromises for something that is still a street car, both how you get the exhaust to the front on the driver's side, accessories and heat problems.

Joining the crossover to the manifold/log cleans a lot of those problems up, gets rid of half the plumbing running back and forth on the passenger side but makes the manifold ugly. Then the debate becomes do you run the log under or over the ports, under gets things pretty tight with the engine mount and crossmember but makes connecting to the crossover much easier, over seems to fit better, leave you with better plug access but makes connecting to the crossover an ugly mess. Putting the log inline with the ports on that side fixes both issues, but then severely restricts the crossover size that you can run through that area.

A tubular K-member would make all this easier by leaving more room, but I'm not convinced that the are really an appropriate solution for street use or a car that is still expected to handle well (I know, this part is seriously debatable)

99xtreme

I am thinking about doing a turbo set up similar to this. It will be on a 91 tpi, and I am planning on keeping the a/c. The turbo in the model is a rough model of a MP T70. Yes I modeled the compressor housing twisting the wrong way. I will eventually fix it, but I just wanted to see it for size comparison. I am working on all of the accessory dimensions now. Don't shoot me, I know the accessory, are not in the correct position, for now.

I downloaded the engine and transmission models, but they seem to be accurate. When I get some time, and it is not raining, I plan on modeling the engine compartment. That way I know what will fit where. Also, if the down pipe is sectional, and held together with V-band clamps, it would be very easy to remove for maintenance.

Orr89RocZ

iTrader: (20)

Its not necessarily going to be pretty but could be functional. Will make servicing the car a bear but it comes with the territory.

You can fab the crossover to connect into the log to elminate some piping. Even using a 2-2.25" crossover will support a good deal of hp, more than enough to break internals on a stock motor if your not careful or as lucky as the "grenade". Tune is one thing but there is some luck too It wont be the best looking setup, and I dont consider the BBS design being that pretty, but its workable.
Keeping A/C presents a big challange in itself. Your limited on pipe size and turbo size. Most T4's are single 3" downpipe and twin 2"-2.25" collectors feeding the frame will be more than enough for your sub 550whp car.

ZZ3Astro

FWIW this is my single turbo manifold. Since you have a 91, this manifold woudn't work with the AC being on the same side. However, since the turbo wouldn't be sitting where the flange is, it seems like you'd have plenty of room to build a merge here that turns out towards the turbo mounting flange instead of turning the crossover towards the manifold as mine is. The point being there is plenty of room to run the crossover from the stock location behind the frame crossmember, and then up and parallel to the passenger side turbo manifold. This leaves plenty of room for a 3" downpipe with the AC box in place as well.

Orr89RocZ

iTrader: (20)

thats basically what I was thinking and actually how my manifold looks like on my twins, minus the crossover and abit more pipe off the header flange to allow downpipe to go between cylinders 6/8.

always tinkerin

iTrader: (1)

That manifold looks as though it would be very simple to reproduce, but would #4 spark plug even fit with the crossover in that location? Angle or Straight plug? Would be interesting to see a pic of it mounted and plug clearance in this area. Plugs are a NIGHTMARE on most turbo setups I've seen, anyway.

noboostnogo

iTrader: (4)

i have a very similar setup to the one you posted but instead my crossover goes under the oil pan in the stock placement. I am sure that you will not be able to fit the turbo next to the a/c compressor and have it clear the hood. My mpt70 sits right where the stock a/c compressor used to be and luckly i have a ram air hood which was wide enough to clear the hood or else i would have had to cut the hood and have the turbo stick out or redo the whole setup. I also do not think your crossover pipe will work unless you have a pinto rack? i think when i was designing mine there was not enough room for a 2.5" crossover.

ZZ3Astro

Yeah plugs are a bit of a pain, however I can remove the entire turbo setup and manifold in about 30-40 minutes and then the plugs are super easy! Plus the new plugs make a nice holder for the manifold when bolting it back in place - you just gotta be careful not to let it snap them off!

You can get to #2 and #8 but 4 and 6 are pretty much impossible with the manifold on.. and that more or less includes the plug wire itself too. I have straight plugs but it appears angle plugs will clear everything. I would be must concerned with #6 for angle plugs, but I actually think it might work better than with straight for that one. My problem is the stock driver side manifold doesn't get along with angle plugs, which limits my head upgrade choices to straight plug until I build a driver side header some day.

ZZ3Astro

This might help show a bit more of the clearance for the crossover and manifold.


And here is another view, looking up at #6 and #8, after I had a bolt work its way loose (note missing washer due to splitting on rough surface which I later smoothed). Can't see much but you can get a better idea of how far the manfiold sticks out relative to the plugs.

Orr89RocZ

iTrader: (20)

You realllly wouldnt like my setup then. Some plugs you can get at from above, some you have to get at from underneath, some you need to move the downpipe and turbo to really reach.... takes me a few hrs to get the entire drivers side manifold off/on. Exhaust bolts are hard to get at. All my plug wires go down the back of the engine, under the manifold except number 1, 2, and 4.

freaky

where are you tapping into to get your oil feed for the turbo ?

noboostnogo

iTrader: (4)

i can get to all the plugs on the passanger side through underneath but its easier to just remove the downpipe and have easy access to them!

always tinkerin

iTrader: (1)

Those pics were worth 1000 words. There is ALOT more clearance than I thought. Thanks for posting.

Mine may be worse than yours for accessing the plugs, Orr. I can hardly see the plugs in my setup. #1,2 wires run on top of manifold to the front and all the rest go around the back. Prolly a couple hour job to change them like you guys.

You can tee off of the oil guage tap behind the intake near the distributor for oil supply.

My crossover is in stock location, but goes from the pass side down under the pan to the driver's side (rather than drivers side to pass side) then wraps around the front of the engine to the merge. This allowed Xtra room for the 4" DP (S480), but sacrificed room near the steering shaft. It's challenging to make your own headers and have them be functional.

HMMM...Looks like the log setup could provide lots more room, be easier to fabricate, take less material, be cheaper to make, and provide a much cleaner looking setup. Wondering what the spool up difference would be between a log versus header style...Prolly no difference. I think the positive aspects of the log setup may outweigh any possible negative spooling effects (if any).

always tinkerin

iTrader: (1)

ZZ3Astro!!!! I just realized...YOU KEPT YOUR A/C!!!! Thats SICK!!!

noboostnogo

iTrader: (4)

ive always wondered what a huge sized turbo like that would look like under our hoods, can you post some pictures of the placement and downpipe?

always tinkerin

iTrader: (1)

http://i1120.photobucket.com/albums/...HOTSIDE005.jpg

I've never tried inserting a link before. Hope it works.

always tinkerin

iTrader: (1)

http://i1120.photobucket.com/albums/...HOTSIDE008.jpg


http://i1120.photobucket.com/albums/...HOTSIDE009.jpg



http://http://i1120.photobucket.com/albums/l484/jessereel/Turbo%20mock-up/HOTSIDE004.jpg

Hope this one works. Just search on Photobucket for user jessereel...that's me.

Orr89RocZ

iTrader: (20)

That looks pretty good. those T6 frames are really big turbos. Lots of pipe running the drivers side

vortec350s10

So I wonder what the best approach would be to making a log style setup. Weld els? I would think that would be easier to weld to the steel weld els than starting off with some sort of stock cast iron manifold and modifying it. What do you guys think? I made a flange out of 3/8" cold rolled, I'm just not sure exactly what route I'm gonna take yet.

always tinkerin

iTrader: (1)

Flange looks great! Shoulda had you make me some!
I like your weld L idea for strength.

Orr89RocZ

iTrader: (20)

weld els in schedule 40 size are most common and would be longest lasting most durable but very heavy. you can find sch. 10 pipe sizes that will work. Even more budget and lighter will be plain mild steel header pipe you can get from summit, but thin wall will wear/rust out quicker. You could get them coated to get abit more life out of them.

I like mild steel since its very easy to work with when it comes to cutting and fitting. Plus you can easily buy cone reducers to build the setup like the above pics. Come off 1 5/8" on last cylinder and 90 deg bend into a straight section, buy a 1 5/8" to 2" and a 2" to 2.5" reducer, weld together to make the main section of the log. Bring the other cylinders into the main log portion. Exactly like zz3astro's post #28.

ZZ3Astro

Some more pics of the manifold that might help if you decide to go that way:









Ignore those square head pipe plugs.. they should have been low profile hex plugs but I was in a hurry. Those things sticking out are always in the way for me!

noboostnogo

iTrader: (4)

i like those flanges!!! are they 1/2"??? did you make those??

EDIT!

i just saw where you said its 3/8"

83 Crossfire TA

iTrader: (2)

Fully optimized, the log manifolds should spool better then header style... and as long as you're willing to deal with crappy plug access, and the extra hassle to work around it, it isn't that hard to keep the AC... you may have to compromise on downpipe size but it's not that hard. I just don't have the patience to deal with working around it on my own stuff.

vortec350s10

Kind of bringing back my old thread, I haven't been doing much over the summer besides slowly building my new 700r4 with Dana's pro street elite kit. I have bought and installed a mini starter and went to a 650 Mighty Demon carb instead of my 650 speed demon vac secondary. I also have an Aeromotive FPR ready to go as well. I bought a fuel pressure gauge 0-15psi, which obviously doesn't go high enough to read once under boost. Seems a lot of people are running a 0-35psi boost gauge as a fuel pressure gauge. Anyone on here have any experience with one? Also I bought a used vac/boost gauge which doesn't read zero. Seems as though this is rather common from what I've researched. Oh well, I can live with it.

99xtreme

Common, i have never seen an autometer boost gauge that read right. I bought one new, and got 3 in parts cars i bought when i was racing my Eagle Talon. None of them read zero, and they all went in the trash after I cracked the ring lands off of 3 out 4 piston in a 90 awd eagle talon with a autometer sport compact gauge reading 14 psi. Engine still ran fine but you could not hold the dipstick in. A buddy let me borrow his Faze gauge and I ran the car just far enough to get in to 2nd and it said i was hitting 24 psi.