Pictures, lessons learned, tips, component sourcing, alloy opinions etc for turbo big blocks, please. My project is a 540 tomahawk with ported stage 2 heads. Looking for 1500 HP at 6500 RPM.
here are my tips: 1. Dont worry about equal length headers when doing turbo headers. Simply route the primaries directly to the turbos will the least amount of welds, bends etc as possible. 2. Mild steel is less prone to cracking and easier to weld. Stainless is brittle. 3. don’t go too large on the primaries, 1-3/4 is fine even at that power level. 4. I would do twin turbos. It’s easier packaging vs one huge turbo. Plus you get to do dual 3-4” exhaust vs a single exhaust. my 350 car has been turbocharged since the mid 90s and after 3 different versions it’s been much improved. Mine has a tri Y design, simple and effective. It’s currently apart getting a better engine, larger turbos, and a better carb hat. finally add exhaust temp probes to each primary. It’s the only way to effectively watch exhaust temps and avoid issue without pulling spark plugs constantly. I still use 02 sensors but the EGT probes are super useful. Pulling plugs is also a huge tool, but EGT is often overlooked with gas turbo setups.
Stainless is preferred for turbo hot side as it is better for heat management. Try not to mix metals as they move differently during heat cycles. Example would be stainless headers and mild steel downpipe. Real estate is the biggest issue with twins. Depending on if it will be race or street will impact decisions too. It's tough to mount twins with a full size radiator etc but it can be done just takes a lot of planning when laying things out.
Just curious what get do you see, whats your max temp b4 you freak out. I have get on my racecar non turbo setup, and top end we see tempsabout 1350 and with the iron heads it went 1425
I’ve seen 1400 as well, that’s not my main focus. What I’m looking at more so is for a variation between cylinders to indicate a lean cylinder (as it will show hotter). This helped me identify my leanest cylinder so I could pull that plug more often to read it. Way rich can show high temps as well however reading the plugs helps me see which side of the scale I’m on. The CSU Holley carbs seem to be almost perfect AFR out of the box, but that’s an average of all 4 cylinders on that bank. It’s vital to find the leanest cylinder when tuning boosted engines. With Diesel it’s more of a max temp issue fir me it’s another tuning tool.
Hey Hey so depending on space i would actually possibly suggest a SINGLE setup because you build only 1x turbo Manifold. you can use the stock manifold on the other side. i would go for a LOG STYLE design using 2- in Exhaust pipe for the log to a T4 Flange. and 1-1/2 or 1-3/4 to the exhaust ports on the heads ( choose whatever gives you good space to the Plugs) I think @sean Buick 76 might still have some manifold flanges which would be great to use. here is a little video of the idea and it can be easily adopted to the Buick. You just have to decide where you want to run the crossover to the stock manifold ( based on how much room you have) - bellow engine/trans - in front of the Pulley and definitly use V-Bands to make it easy to take off. twins are great but you have to build everything 2 times 2 turbos, 2 wastegates 2 turbo headers i build some turbo headers for a 4.8LS i have sitting around it will have a 78/75 T4 The LS manifolds are cast steal so easy to weld on . they not pretty but will be functional and after wrapping the hot /turbo side with exhaust wrap you cant see my ugly welds " a grinder & paint makes me the welder i ain"t" PS: Dont even try to perfect the flow of your design , trust me you will have enough flow for any power level up to 1500hp. so it litterally doesnt matter much on the log style. Crossover 2.5 in. is capable of 2K hp Just make sure your Turbo can breath if its a 3" vband on the exhaust side give it min. 3" pipe I actually would like to do this job on a 455 if i had a spare one
My neighbor builds these, and they have hit 1800 Hp with them. It uses a factory manifold on the driver side feeding into this passenger side then to the turbo.
If You provide him a 455 block/Head and he can conture this log styles based on the factory manifold design for the 455 i think he has some customers
To each his own but I don't think I'm putting log manifolds on a 6k block. If your building a Tomahawk you're putting together a serious piece that will make legit power. Log manifolds are going to have flow limitations. There's a reason serious builds don't use them. Sure they serve a purpose and will work but I'm gonna need some nice stuff to go with that Tomahawk bling. No offense meant to the guys that are using them. Stainless headers for the win.
It’s not hard to find a local fabricator to build custom headers or manifolds. Header cost isn’t much of an issue with a 30 thousand dollar plus engine.
Nobody mentioned that it should go on a Tomahawk. i thought it goes on a stocker... IF tomahawk why Boost at all? now you talking 10-12K basic setup i buy a car /truck motors, perf parts rearend and trans for that $$
Did you read the op's post? It's a Tomahawk build. And you boost it to make big power. Otherwise a stock block will suffice for moderate street power.
Touche " i have not read that part lol. You are absolutely right , when spending the $ for a Tomahawk ( i wish i could) then you should get "good" parts to dress it up lol
I do have some welding experience on my own restoration, wife's cullender handle, flitch plate floor beams, stainless tips to aluminized, helium gas added to argon for thick alum cast, etc. I started yrs ago with a Daytona Mig Tig scratch start (demo'd in Daytona) but love my Lincoln Invertec 205-T currently (demo'd at Air Venture the yr the A380 Landed). So I'd prefer to fab my own. Pictures, lessons learned, tips, component sourcing, alloy opinions pls. And thanks for everyone's input so far!
If you are going to build them yourself and you aren’t a pro then I would for sure use thick Mild steel for your first attempt. The skill level to perfect stainless is far higher vs mild. A perfectly done stainless set is likely superior however an amateur job is much more likely to crack vs an amateur mild set.
Liked Sean's tri-y manifolds. Any other pics, lessons learned, tips, component sourcing, alloy opinions are welcome. And thanks for everyone's input so far!
Just picked this 455/th400 combo up. I will mock up a turbo log ... Most likely can't accommodate stock AC due to space issues ....let's see what we can do.
Thanks Brother' i will design something that will be sufficent for the stock block stock rods and stock pistons max up to 800hp ( i hope) the 455 i got is a virgin block so the seller ( i hope so = thicker walls) , so i consider a T4 turbo Flange for a GT45 or T76 i think , actually i have t4 78/75 here so that will be the main model and maybe based on the CI a better option OR we getting already into the "Overkill" area where the stock parts will be more than challenged. however i think this + relativly basic upgrades such as Heads with Stage 1/bigger valves and springs (blocking the exhaust cross over if needed) and a mild to medium Cam and most important a single plane Alu intake ( much cooler intake temp) can get us in the area, when we are arround 12-14 psi ( 14 will be alot already on stock internals). OH what i will do is inspect the pistons and put new "gapped" rings on it ( i think thats essential) + looking at rod and main bearings while in there. For fuel i would probably look into a Holley Sniper EFI boost unit, even though CSU carbs are awesome i am done with boost/carb stuff personally lol
